saccharides which may used in this invention include , but not limited to , residues derived from d - and l - type natural monosaccharides including 6 - deoxysaccharides such as fucose , rhamnose , digitoxose , oleandrose and quinovose , hexoses such as allose , altrose , glucose , mannose , gulose , idose , galactose and talose , pentoses such as ribose , arabinose , xylose and lyxose , tetroses such as erythrose and threose , aminosaccharides such as glucosamine and daunosamine , uronic acids such as glucuronic acid and galacturonic acid , ketoses such as psicose , fructose , sorbose , tagatose and pentulose , and deoxysaccharides such as 2 - deoxyribose ; residues derived from synthetic pyranose and furanose saccharides ; and saccharide residue derivatives in which hydroxy and / or amino groups in any of the above residues are protected or acylated or saccharides having a halogenated saccharide residue in which hydroxy is replaced with halogen such as fluorine . in this invention , a 1 - phosphorylated saccharide derivative refers to a saccharide derivative in which among residues derived from natural or synthetic monosaccharide , 1 - hydroxy is phosphorylated . unless otherwise indicated , it may include a monomer , dimer or trimer or a mixture thereof , where there are no restrictions to its mixture ratio . a protective group in terms of “ protected hydroxymethyl ” and “ a protective group of hydroxy ” means that which may be removed by an appropriate chemical process such as hydrogenolysis , hydrolysis and photolysis , including formyl , acyl , silyl , alkyl , aralkyl , carbonyl , preferably formyl , aliphatic acyl , aromatic acyl , silyl , alkoxyalkyl , halogenated alkyl , aralkyl , alkoxycarbonyl and aralkyloxycarbonyl . examples of alkylcarbonyl include acetyl , propionyl , butyryl , isobutyryl , pentanoyl , pivaloyl , valeryl , isovaleryl , octanoyl , nonylcarbonyl , decylcarbonyl , 3 - methylnonylcarbonyl , 8 - methylnonylcarbonyl , 3 - ethyloctylcarbonyl , 3 , 7 - dimethyloctylcarbonyl , undecylcarbonyl , dodecylcarbonyl , tridecylcarbonyl , tetradecylcarbonyl , pentadecylcarbonyl , hexadecylcarbonyl , 1 - methylpentadecylcarbonyl , 14 - methylpentadecylcarbonyl , 13 , 13 - dimethyltetradecylcarbonyl , heptadecylcarbonyl , 15 - methylhexadecylcarbonyl and octadecylcarbonyl . examples of halogenated lower alkylcarbonyl include chloroacetyl , dichloroacetyl , trichloroacetyl and trifluoroacetyl . aromatic acyl may be arylcarbonyl , halogenated arylcarbonyl , lower - alkylated arylcarbonyl , lower - alkoxylated arylcarbonyl , nitrated arylcarbonyl , lower - alkoxycarbonylated arylcarbonyl or arylated arylcarbonyl . examples of halogenated arylcarbonyl include 2 - fluorobenzoyl , 3 - fluorobenzoyl , 4 - fluorobenzoyl , 2 - chlorobenzoyl , 3 - chlorobenzoyl , 4 - chlorobenzoyl , 2 - bromobenzoyl , 3 - bromobenzoyl , 4 - bromobenzoyl , 2 , 4 - dichlorobenzoyl , 2 , 6 - dichlorobenzoyl , 3 , 4 - dichlorobenzoyl and 3 , 5 - dichlorobenzoyl . examples of lower - alkyl silyl include trimethylsilyl , triethylsilyl , isopropyldimethylsilyl , tert - butyldimethylsilyl , methyldiisopropylsilyl and triisopropylsilyl . aralkyl may be benzyl , aralkyl substituted with lower alkyl , aralkyl substituted with lower alkoxy , aralkyl substituted with nitro , aralkyl substituted with halogen or aralkyl substituted with cyano . examples of these include 2 - methylbenzyl , 3 - methylbenzyl , 4 - methylbenzyl , 2 , 4 , 6 - trimethylbenzyl , 2 - methoxybenzyl , 3 - methoxybenzyl , 4 - methoxybenzyl , 2 - nitrobenzyl , 3 - nitrobenzyl , 4 - nitrobenzyl , 2 - chlorobenzyl , 3 - chlorobenzyl , 4 - chlorobenzyl , 2 - bromobenzyl , 3 - bromobenzyl , 4 - bromobenzyl , 2 - cyanobenzyl , 3 - cyanobenzyl and 4 - cyanobenzyl . aralkyloxycarbonyl may be aralkyloxycarbonyl substituted with lower alkyl , aralkyloxycarbonyl substituted with lower alkoxy , aralkyloxycarbonyl substituted with nitro , aralkyloxycarbonyl substituted with halogen or aralkyloxycarbonyl substituted with cyano . examples of these include 2 - methylbenzyloxycarbonyl , 3 - methylbenzyloxycarbonyl , 4 - methylbenzyloxycarbonyl , 2 , 4 , 6 - trimethylbenzyloxycarbonyl , 2 - methoxybenzyloxycarbonyl , 3 - methoxybenzyloxycarbonyl , 4 - methoxybenzyloxycarbonyl , 2 - nitrobenzyloxycarbonyl , 3 - nitrobenzyloxycarbonyl , 4 - nitrobenzyloxycarbonyl , 2 - chlorobenzyloxycarbonyl , 3 - chlorobenzyloxycarbonyl , 4 - chlorobenzyloxycarbonyl , 2 - bromobenzyloxycarbonyl , 3 - bromobenzyloxycarbonyl , 4 - bromobenzyloxycarbonyl , 2 - cyanobenzyloxycarbonyl , 3 - cyanobenzyloxycarbonyl and 4 - cyanobenzyloxycarbonyl . examples of lower - alkoxycarbonyl include methoxycarbonyl , ethoxycarbonyl , propoxycarbonyl , butoxycarbonyl , sec - butoxycarbonyl and tert - butoxycarbonyl . alkyl may be alkoxyalkyl such as methoxyethyl , ethoxymethyl , 2 - methoxyethyl and 2 - methoxyethoxymethyl ; halogenated alkyl such as 2 , 2 , 2 - trichloroethyl ; or lower alkyl substituted with aryl such as benzyl , α - naphthylmethyl , β - naphthylmethyl , diphenylmethyl and triphenylmethyl . among these , aliphatic acyl , aromatic acyl and aralkyl are preferable ; 4 - toluoyl , 4 - chlorobenzoyl and benzyl are more preferable . a protective group in terms of “ protected carboxyl ” in r 1 and r 2 refers to that which may be removed by an appropriate chemical process such as hydrogenolysis , hydrolysis and photolysis , including preferably lower alkyl such as methyl , ethyl , n - propyl , isopropyl , n - butyl , isobutyl , sec - butyl and tert - butyl ; silylated lower alkyl such as 2 -( trimethylsilyl ) ethyl and 2 -( triethylsilyl ) ethyl ; or the above aralkyl or alkoxyalkyl , more preferably methyl , tert - butyl or benzyl . halogen in terms of x refers to fluorine , chlorine , = bromine or iodine . alkoxy and alkylthio in terms of x may be alkoxy and alkylthio having the above lower alkyl , aralkyl or alkoxyalkyl , preferably methoxy , methoxyethoxy or methylthio . optionally substituted carbon in terms of z refers to carbon having one or two of the substituent represented by the formula ( xq and nhr 3 ) or when having no substituents , carbon having hydrogen atoms . acyl in terms of r 3 may be the above aliphatic acyl , aromatic acyl , alkoxycarbonyl or aralkyloxycarbonyl , or lower - alkanesulfonyl such as methanesulfonyl and trifluoromethanesulfonyl or arylsulfonyl such as benzenesulfonyl and p - toluenesulfonyl ; preferably , aliphatic acyl , aromatic acyl or lower - alkanesulfonyl ; specifically , acetyl , trifluoroacetyl , benzoyl and methanesulfonyl . when more than one of nhr 3 are used as a substituent , r 3 s in individual nhr 3 independently represent any of the above radicals . a protective group in “ protected hydroxymethyl ” and “ a protective group for hydroxy ” in terms of r 4 , r 11 and r 14 may be selected from those described for r 1 and r 2 . saccharide residues having a structure represented by any of formulas ( 1 ) to ( 17 ) may be preferably , but not limited to , those derived from a natural monosaccharide described above , those derived from a synthetic saccharide , derivatives from the saccharide residues or halogenated saccharide residues , as described above . salts of a compound represented by any of formulas ( 4 ) to ( 7 ) may be those formed by a phosphate radical in the compound . examples of such a salt include alkali metal salt such as sodium , potassium and lithium salts ; alkaline earth metal salt such as magnesium , calcium and barium salts ; metal salt such as aluminum and iron salts ; ammonium salt ; or alkylamine salt such as primary , secondary and tertiary alkyl amine salts . primary amine herein may be alkylamine such as methylamine , ethylamine , propylamine , isopropylamine , butylamine , hexylamine and octylamine ; cycloalkylamine such as cyclohexylamine ; or benzylamine . secondary amine may be dialkylamine such as diethylamine , diisopropylamine , dibutylamine , dihexylamine and dioctylamine ; dicycloalkylamine such as dicyclohexylamine ; or cyclic amine such as piperidine , morpholine and n - methylpiperadine . tertiary amine may be tertiary - alkylamine such as trimethylamine , triethylamine , tripropylamine , n - ethyldiisopropylamine , tributylamine , trihexylamine , trioctylamine , n - ethyldicyclohexylamine , n - methylpiperidine , n - methylmorpholine and n , n , n ′, n ′- tetramethylethylenediamine ; aniline compound such as aniline , n , n - dimethylaniline , n , n - diethylaniline , n , n - dibutylaniline and n , n - dioctylaniline ; pyridine compound such as pyridine , 2 , 6 - dimethylpyridine , 2 , 4 , 6 - lutidine and nicotinamide ; amino acid such as glycine , alanine , proline , lysine , arginine and glutamine ; or optically active amine such as cinchonidine , 1 -( 1 - naphthyl ) ethylamine and 1 - phenylethylamine , all of which include monovalent and bivalent salts . a compound represented by any of formula ( 4 ) to ( 7 ) of this invention may absorb moisture to have adsorbed water or become a hydrate , all of which may be encompassed by this invention . an anomer mixture of a 1 - phosphorylated saccharide derivative according to this invention may be prepared by , but not limited to , a reaction represented by reaction formula ( i ): in this formula , r 1 , r 2 , r 3 , r 4 , x , w , z , m , n , p , q and r are as defined for formula ( 1 ), and y represents fluorine , chlorine , bromine or iodine . when m is 1 , 2 or 3 , phosphoric acid tri -, di - or mono - ester is provided , respectively . these are referred to as 1 - phosphorylated saccharide derivative trimer , 1 - phosphorylated saccharide derivative dimer and 1 - phosphorylated saccharide derivative monomer , respectively . furthermore , 1 - phosphorylated saccharide derivative trimer , 1 - phosphorylated saccharide derivative dimer and 1 - phosphorylated saccharide derivative monomer are collectively referred to as a 1 - phosphorylated saccharide derivative , for which there are no restrictions to its mixture ratio . a preferable phosphoric acid may be , but not limited to , one with a lower water content such as orthophosphoric acid . there are no restrictions to a base as long as it does not inhibit the reaction and functions as a deoxidizer . preferable inorganic bases include carbonates and hydroxides of alkali and alkaline earth metals . preferable organic bases include tertiary alkylamines , anilines , pyridines and optically active amines . a dehydrating agent may be used when moisture from = a solvent or an additive adversely affects the reaction . there are no restrictions to a dehydrating agent as long as it has adequate adsorptivity or reactivity with water ; preferably molecular sieves and phosphorus pentoxide . the reaction is generally conducted in the presence of a solvent . there are no restrictions to a solvent as long as it does not inhibit the reaction and dissolve starting materials to some degree . solvents which may be used include aliphatic hydrocarbons such as hexane and heptane ; aromatic hydrocarbons such as benzene , toluene , xylene and anisole ; halogenated hydrocarbons such as methylene chloride , chloroform , carbon tetrachloride , dichloroethane , chlorobenzene and dichlorobenzene ; esters such as ethyl formate , ethyl acetate , propyl acetate , n - butyl acetate and diethyl carbonate ; ethers such as diethyl ether , diisopropyl ether , tetrahydrofuran , dioxane , dimethoxyethane and diglyme ; nitriles such as acetonitrile , propionitrile and isobutylnitrile ; amides such as formamide , n , n - dimethylformamide , n , n - dimethylacetamide , n - methyl - 2 - pyrrolidone , n - methylpyrrolidinone and n , n - dimethyl - 2 - imidazolydinone ; ketones such as acetone , 2 - butanone , methyl isopropyl ketone and methyl isobutyl ketone ; and a mixture of two or more selected therefrom . there are no restrictions to a reaction temperature ; generally − 80 ° c . to 60 ° c ., preferably − 10 ° c . to 25 ° c . a reaction period may vary depending on many factors such as starting materials , reagents , the type of a solvent and a reaction temperature ; generally 1 min to 24 hours , preferably 10 min to 2 hours for completing the reaction . there are no restrictions to a ratio of a saccharide derivative ( 14 ) to phosphoric acid ; the reaction is generally conducted with a ratio of compound ( 14 ): phosphoric acid = 1 : 10 to 3 : 1 . in this case , the product ( 1 ) may be a mixture of the compounds whose saccharide residue number ( i . e ., m ) coupled with phosphoric acid is 1 , 2 or 3 , depending on the ratio of compound ( 14 ): phosphoric acid . furthermore , a 1 - phosphorylated saccharide derivative ( 16a ) or ( 16b ) with either α - or β - form may be prepared by a reaction represented by reaction formula ( ii ): in this formula , r 1 , r 2 , r 3 , r 4 , x , w , z , m , n , p , q and r are as defined for formula ( 1 ). according to this preparation process , the 1 - phosphorylated saccharide derivative represented by formula ( 15 ) may be a monomer , dimer or trimer or a mixture thereof in any mixture ratio because they may be converted into the 1 - phosphorylated saccharide derivative represented by formula ( 16 ) in the reaction system . a preferable phosphoric acid may be , but not limited to , one with a lower water content such as orthophosphoric acid . a base is important for forming a salt with the phosphate group in compound ( 16 ) to selectively crystallize one of α - and β - compounds , ( 16a ) or ( 16b ). the most suitable base may be selected in the light of a solvent used in the reaction ; preferably , the above inorganic bases , tertiary alkylamines , anilines , = pyridines , amino acids and optically active amines , and salts formed include monovalent and bivalent salts . a dehydrating agent may be used when moisture from a solvent or an additive adversely affects the reaction . there are no restrictions to a dehydrating agent as long as it has adequate adsorptivity or reactivity with water ; preferably molecular sieves and phosphorus pentoxide . the reaction is generally conducted in the presence of a solvent . there are no restrictions to a solvent as long as it does not inhibit the reaction , dissolve starting materials to some degree and promotes selective crystallization of one of the α - and β - forms , ( 16a ) or ( 16b ), generated by salt formation of the phosphate group in compound ( 16 ), including the above aliphatic hydrocarbons , aromatic hydrocarbons , halogenated hydrocarbons , esters , ethers , nitrites , amides , ketones and a mixture of two or more selected therefrom . there are no restrictions to a reaction temperature as long as it accelerates the equilibrium reaction between compounds ( 15 ) and ( 16 ) for promoting selective crystallization of one of the α - and β - forms , ( 16a ) or ( 16b ), generated by salt formation of the phosphate group in compound ( 16 ); generally − 80 ° c . to 60 ° c ., preferably − 10 ° c . to 25 ° c . a reaction period may vary depending on many factors such as starting materials , reagents , the type of a solvent and a reaction temperature ; generally 3 hours to 1 week , preferably 6 hours to 24 hours for completing the reaction . there are no restrictions to a ratio of a saccharide derivative ( 1 ) to phosphoric acid ; the reaction is generally conducted with a ratio of compound ( 1 ): phosphoric acid = 1 : 10 to 3 : 1 , where the ph of the reaction system is generally 1 to 7 , suitably in an acidic range from 1 to 4 . the 1 - phosphorylated saccharide derivative ( 16a ) or ( 16b ) with either α - or β - form may be isolated as a phosphate with a base other than that used in the reaction system by a salt - exchange reaction . bases which may be herein used include the above inorganic bases , primary alkylamines , secondary alkylamines , tertiary alkylamines , anilines , pyridines , amino acids and optically active amines , and salts formed include monovalent and bivalent salts . the protective group may be removed by reaction formula ( iii ) to prepare a 1 - phosphorylated saccharide derivative ( 17a ) or ( 17b ). in this formula , r 1 , r 2 , r 3 , r 4 , x , w , z , n , p , q and r are as defined for formula ( 1 ); r 1 ′ and r 2 ′ independently represent hydrogen , methyl , hydroxymethyl or carboxyl ; and r 3 ′ represents hydrogen or acyl . when using the above aliphatic acyl , aromatic acyl or alkoxy carbonyl as a protective group for hydroxymethyl in r 1 and r 2 or hydroxy in r 4 , or using the above lower alkyl as a protective group for carboxyl in r 1 and r 2 in compound ( 16a ) or ( 16b ), it may be removed by treating the compound with a base in an aqueous solvent . bases which may be used include preferably alkali metal carbonates such as sodium carbonate and potassium carbonate ; alkali metal hydroxides such as lithium hydroxide , sodium hydroxide and potassium hydroxide ; ammonium hydroxides such as ammonium hydroxide and tetra - n - butylammonium hydroxide ; and the above inorganic bases , primary alkylamines , secondary alkylamines and tertiary alkylamines . solvents which may be used include , with no restrictions , those used in a common hydrolysis ; preferably water ; alcohols such as methanol , ethanol , n - propanol and isopropanol ; and the above ethers . a reaction temperature and a reaction period vary , with no restrictions , depending on many factors such as starting materials and a base used ; generally the reaction may be completed at − 10 ° c . to 100 ° c . for 1 hour to 5 days . the protective group r 3 may be left or simultaneously removed as appropriate by adjusting a reaction temperature , a reaction period and the equivalent values of reagents . when using the above aralkyl or aralkyloxycarbonyl as a protective group for hydroxymethyl in r 1 and r 2 or hydroxy in r 4 or using the above aralkyl as a protective group for carboxy in r 1 and r 2 in compound ( 16a ) or ( 16b ), they may be removed by , for example , catalytic hydrogenation using a metal catalyst . the catalyst may be preferably selected from palladium - carbon , raney nickel , platinum oxide , platinum black , rhodium - aluminum oxide , triphenylphosphine - rhodium chloride and palladium - barium sulfate . there are no restrictions to a reaction pressure . generally , a solvent used may be any of those used in a common hydrolysis with no restrictions . it may be preferably selected from water ; alcohols such as methanol , ethanol , n - propanol and isopropanol ; the above ethers ; and the above esters . a reaction temperature and a reaction period vary , with no restrictions , depending on many factors such as starting materials and a base used ; generally the reaction may be completed at − 10 ° c . to 100 ° c . for 1 hour to 5 days . the protective group r 3 may be generally left . when using the above silyl as a protective group for hydroxymethyl in r 1 and r 2 or hydroxy in r 4 or using the above silylated lower alkyl as a protective group for carboxy in r 1 and r 2 in compound ( 16a ) or ( 16b ), they may be removed by , for example , using a compound which can generate fluoride anion such as tetra - n - butylammonium fluoride . there are no restrictions to a solvent as long as it does not inhibit the reaction ; for example , the above ethers may be used . a reaction temperature and a reaction period vary , with no restrictions , depending on many factors such as starting materials and a base used ; generally the reaction may be completed at − 10 ° c . to 50 ° c . for 10 min to 10 hours . the protective group r 3 may be generally left . in removing any protective group , a phosphate group in a product is obtained as a salt with a base present in a reaction system . the salt may be , if necessary , converted into a salt with another base . in such a case , a base used may be selected from the above inorganic bases , primary alkylamines , secondary alkylamines , tertiary alkylamines , anilines , pyridines , amino acids and optically active amines , and salts formed include monovalent and bivalent salts . a 1 - phosphorylated saccharide derivative as used herein is a saccharide or its derivative in which a phosphoric acid moiety is coupled at 1 - position via an ester linkage . wherein r 1 and r 2 independently represent hydrogen , methyl , hydroxymethyl or carboxy ; r 3 , x , w , z , n , p , q and r are as defined for formula ( 4 ). typical examples include , but not limited to , ribose - 1 - phosphate , 2 - deoxyribose - 1 - phosphate , 2 , 3 - dideoxyribose - 1 - phosphate and arabinose - 1 - phosphate , but any derivative may be used without distinction as long as it can be obtained by any of the above highly universal and anomer - selective preparation processes . examples of a saccharide derived from a natural product which constitutes a 1 - phosphorylated saccharide derivative include , but not limited to , aldopentoses such as d - arabinose , l - arabinose , d - xylose , l - lyxose and d - ribose ; ketopentoses such as d - xylose , l - xylose and d - ribulose ; aldohexoses such as d - galactose , l - galactose , d - glucose , d - talose and d - mannose ; ketohexoses such as d - tagatose , l - sorbose , d - psicose and d - fructose ; deoxysaccharides such as d - 2 - deoxyribose , d - 2 , 3 ,- dideoxyribose , d - fucose , l - fucose , d - rhamnose , l - rhamnose , d - fucopyranose , l - fucopyranose , d - rhamnofuranose , l - rhamnofuranose , d - allomethylose , d - quinovose , d - antiallose , d - talomethylose , l - talomethylose , d - digitalose , d - digitoxose , d - cymarose , tyvelose , abequose , paratose , colitose and ascarilose ; aminosaccharides such as glucosamine and daunosamine ; and uronic acids such as glucuronic acid and galacturonic acid . there will be described a process for preparing a nucleoside according to this invention . a base used in this process is a natural or synthetic base selected from pyrimidine , purine , azapurine and deazapurine , which may be substituted with halogen , alkyl , haloalkyl , alkenyl , haloalkenyl , alkynyl , amino , alkylamino , hydroxy , hydroxyamino , aminoxy , alkoxy , mercapto , alkylmercapto , aryl , aryloxy and / or cyano . examples of halogen as a substituent include chlorine , fluorine , bromine and iodine . examples of alkyl include lower alkyls with 1 to 7 carbon atoms such as methyl , ethyl and propyl . examples of haloalkyl include those having an alkyl with 1 to 7 carbon atoms such as fluoromethyl , difluoromethyl , trifluoromethyl , bromomethyl and bromoethyl . examples of alkenyl include those with 2 to 7 carbon atoms such as vinyl and allyl . examples of haloalkyl include those having alkenyl with 2 to 7 carbon atoms such as bromovinyl and chlorovinyl . examples of alkynyl include those with 2 to 7 carbon atoms such as ethynyl and propynyl . examples of alkylamino include those having alkyl with 1 to 7 carbon atoms such as methylamino and ethylamino . examples of alkoxy include those with 1 to 7 carbon atoms such as methoxy and ethoxy . examples of alkylmercapto include those having alkyl with 1 to 7 carbon atoms such as methylmercapto and ethylmercapto . examples of aryl include phenyl ; alkylphenyls having alkyl with 1 to 5 carbon atoms such as methylphenyl and ethylphenyl ; alkoxyphenyls having alkoxy with 1 to 5 carbon atoms such as methoxyphenyl and ethoxyphenyl ; alkylaminophenyls having alkylamino with 1 to 5 carbon atoms such as dimethylaminophenyl and diethylaminophenyl ; and halogenophenyls such as chlorophenyl and bromophenyl . examples of a pyrimidine base include cytosine , uracil , 5 - fluorocytosine , 5 - fluoro uracil , 5 - chlorocytosine , 5 - chlorouracil , 5 - bromocytosine , 5 - bromouracil , 5 - iodocytosine , 5 - iodouracil , 5 - methylcytosine , 5 - methyluracil ( thymine ), 5 - ethylcytosine , 5 - ethyluracil , 5 - fluoromethylcytosine , 5 - fluoromethyluracil , 5 - trifluorocytosine , 5 - trifluorouracil , 5 - vinyluracil , 5 - bromovinyluracil , 5 - chlorovinyluracil , 5 - ethynylcytosine , 5 - ethynyluracil , 5 - propynyluracil , pyrimidin - 2 - one , 4 - hydroxyaminopyrimidin - 2 - one , 4 - aminoxypyrimidin - 2 - one , 4 - methoxypyrimidin - 2 - one , 4 - acetoxypyrimidin - 2 - one , 4 - fluoropyrimidin - 2 - one and 5 - fluoropyrimidin - 2 - one . examples of a purine base include purine , 6 - aminopurine ( adenine ), 6 - hydroxypurine , 6 - fluoropurine , 6 - chloropurine , 6 - methylaminopurine , 6 - dimethylaminopurine , 6 - trifluoromethylaminopurine , 6 - benzoylaminopurine , 6 - acetylaminopurine , 6 - hydroxyaminopurine , 6 - aminoxypurine , 6 - methoxypurine , 6 - acetoxypurine , 6 - benzoyloxypurine , 6 - methylpurine , 6 - ethylpurine , 6 - trifluoromethylpurine , 6 - phenylpurine , 6 - mercaptopurine , 6 - methylmercaptopurine , 6 - aminopurine - 1 - oxide , 6 - hydroxypurine - 1 - oxide , 2 - amino - 6 - hydroxypurine ( guanine ), 2 , 6 - diaminopurine , 2 - amino - 6 - chloropurine , 2 - amino - 6 - iodopurine , 2 - aminopurine , 2 - amino - 6 - mercaptopurine , 2 - amino - 6 - methylmercaptopurine , 2 - amino - 6 - hydroxyaminopurine , 2 - amino - 6 - methoxypurine , 2 - amino - 6 - benzoyloxypurine , 2 - amino - 6 - acetoxypurine , 2 - amino - 6 - methylpurine , 2 - amino - 6 - cyclopropylaminomethylpurine , 2 - amino - 6 - phenylpurine , 2 - amino - 8 - bromopurine , 6 - cyanopurine , 6 - amino - 2 - chloropurine ( 2 - chloroadenine ) and 6 - amino - 2 - fluoropurine ( 2 - fluoroadenine ). examples of an azapurine and a deazapurine bases include 6 - amino - 3 - deazapurine , 6 - amino - 8 - azapurine , 2 - amino - 6 - hydroxy - 8 - azapurine , 6 - amino - 7 - deazapurine , 6 - amino - 1 - deazapurine and 6 - amino - 2 - azapurine . a nucleoside phosphorylase is a generic name for enzymes capable of phosphorolysis of an n - glycoside bond in a nucleoside in the presence of phosphoric acid and this invention utilizes its reverse reaction . an enzyme used in the reaction may be of any type or origin as long as it has an activity of forming a desired nucleoside from a corresponding 1 - phosphorylated saccharide derivative and a base . the enzymes may be generally categorized into two types , purine and pyrimidine types . examples of a purine type enzyme include purine nucleoside phosphorylase ( ec2 . 4 . 2 . 1 ) and guanosine nucleoside phosphorylase ( ec2 . 4 . 2 . 15 ). examples of a pyrimidine type enzyme include pyrimidine nucleoside phosphorylase ( ec2 . 4 . 2 . 2 ), uridine nucleoside phosphorylase ( ec2 . 4 . 2 . 3 ), thymidine nucleoside phosphorylase ( ec2 . 4 . 2 . 4 ) and deoxyuridine nucleoside phosphorylase ( ec2 . 4 . 2 . 23 ). a microorganism expressing a nucleoside phosphorylase in this invention may be , with no restrictions , any microorganism expressing at least one nucleoside phosphorylase selected from the group consisting of purine nucleoside phosphorylase ( ec2 . 4 . 2 . 1 ), guanosine nucleoside phosphorylase ( ec2 . 4 . 2 . 15 ), pyrimidine nucleoside phosphorylase ( ec2 . 4 . 2 . 2 ), uridine nucleoside phosphorylase ( ec2 . 4 . 2 . 3 ), thymidine nucleoside phosphorylase ( ec2 . 4 . 2 . 4 ) and deoxyuridine nucleoside phosphorylase ( ec2 . 4 . 2 . 23 ). preferable examples of such a microorganism include strains belonging to nocardia , microbacterium , corynebacterium , brevibacterium , cellulomonas , flabobacterium , kluyvere , micobacterium , haemophilus , micoplana , protaminobacter , candida , saccharomyces , bacillus , thermophile bacillus , pseudomonas , micrococcus , hafnia , proteus , vibrio , staphyrococcus , propionibacterium , sartina , planococcus , escherichia , kurthia , rhodococcus , acinetobacter , xanthobacter , streptomyces , rhizobium , salmonella , klebsiella , enterobacter , erwinia , aeromonas , citrobacter , achromobacter , agrobacterium , arthrobacter and pseudonocardia . recent advance in molecular biology and genetic engineering has allowed us to analyze molecular - biological properties , an amino acid sequence and so on of a nucleoside phosphorylase in the above strain for obtaining the gene for the protein from the strain , to constitute a recombinant plasmid in which a control region required for the gene and its expression is inserted , to introduce the plasmid into a given host and to produce a gene recombinant strain expressing the protein , and these processes have become relatively easier . in the light of the recent technical level , such a gene recombinant strain in which a gene for a nucleoside phosphorylase is introduced in a given host shall be also included in a microorganism expressing a nucleoside phosphorylase according to this invention . a control region required for expression herein may be a promoter sequence ( including an operator sequence controlling transcription ), a ribosome binding sequence ( sd sequence ), a transcription termination sequence , or the like . examples of a promoter sequence include a trp operator in a tryptophane operon derived from e . coli ; a lac promoter in a lactose operon ; a pl and a pr promoters derived from lambda phage ; a gluconate synthase promoter ( gnt ) derived from bacillus subtilis ; an alkali protease promoter ( apr ); a neutral protease promoter ( npr ); and α - amylase promoter ( amy ). a uniquely modified and designed sequence such as a tac promoter may be used . a ribosome linkage sequence may be , for example , a sequence derived from e . coli or bacillus subtilis , but any sequence may be used as long as it can function in a desired host such as e . coli and bacillus subtilis . for example , one can use a consensus sequence formed by dna synthesis , that is , a sequence with more than 4 consecutive bases complementary to 3 ′- terminal region in 16s ribosome rna . a transcription termination sequence is not always necessary , but a ρ - factor independent terminator such as a lipoprotein terminator and a trp operon terminator may be used . desirably , these control regions on a recombinant plasmid may be sequentially aligned as follows ; from upstream of 5 ′- terminal , a promoter sequence , a ribosome linkage sequence , a nucleoside phosphorylase coding gene and a transcription termination sequence . as examples of a plasmid herein , pbr 322 , puc18 , bluescript ii sk (+), pkk223 - 3 and psc101 having an autonomously replicable region in e . coli ; pub110 , ptz4 , pc194 , ρ11 , φ1 and φ105 having an autonomously replicable region in bacillus subtilis may be used as a vector . as examples of a plasmid autonomously replicable in two or more hosts , phv14 , trp7 , yep7 and pbs7 may be used as a vector . a given host herein may be typically , but not limited to , escherichia coli as described in examples later , but other strains such as bacillus sp . including bacillus subtilis , yeasts and actinomyces may be used . nucleoside phosphorylase activity in this invention may be obtained from , besides the above strains having the enzyme activity , a processed material of the strain exhibiting the enzyme activity and an immobilized product thereof . a processed material of the strain may be , for example , acetone - dried strain or a bacterial debris prepared by an appropriate procedure such as mechanical destruction , ultrasonic disintegration , freezing and thawing , pressurization and depressurization , osmotic pressure method , autolysis , cell - wall decomposition and surfactant treatment . if necessary , the strain may be further purified by ammonium sulfate precipitation , acetone precipitation or column chromatography . in this invention , a metal cation capable of forming a water - insoluble salt with phosphate ion may be , without restriction , any metal cation which can form a water - insoluble salt with phosphate ion as a byproduct in the reaction and may be precipitated ; for example , calcium , magnesium , barium , iron , cobalt , nickel , copper , silver , molybdenum , lead , zinc and lithium ions . among these , particularly preferable are industrially universal and safe metal ions which do not adversely affect the reaction , e . g ., calcium , barium , aluminum and magnesium ions . a metal cation capable of forming a water - insoluble salt with phosphate ion in this invention may be obtained by adding a salt of a metal cation capable of forming a water - insoluble salt with phosphate ion with at least one anion selected from chloride , nitride , carbonate , sulfate , acetate and hydroxyl ions into the reaction solution . examples of such a salt include calcium chloride , calcium nitride , calcium carbonate , calcium sulfate , calcium acetate , barium chloride , barium nitride , barium carbonate , barium sulfate , barium acetate , aluminum chloride , aluminum nitride , aluminum carbonate , aluminum sulfate , aluminum acetate , calcium hydroxide , barium hydroxide , aluminum hydroxide , magnesium hydroxide , magnesium chloride , magnesium nitride , magnesium carbonate , magnesium sulfate and magnesium acetate . such a metal cation may be present as a salt with a pentose - 1 - phosphate in the reaction solution ; for example , ribose - 1 - phosphate calcium salt , 2 - deoxyribose - 1 - phosphate calcium salt , 2 , 3 - dideoxyribose - 1 - phosphate calcium salt , arabinose - 1 - phosphate calcium salt , ribose - 1 - phosphate barium salt , 2 - deoxyribose - 1 - phosphate barium salt , 2 , 3 - dideoxyribose - 1 - phosphate barium salt , arabinose - 1 - phosphate barium salt , ribose - 1 - phosphate aluminum salt , 2 - deoxyribose - 1 - phosphate aluminum salt , 2 , 3 - dideoxyribose - 1 - phosphate aluminum salt and arabinose - 1 - phosphate aluminum salt . a reaction for preparing a nucleoside compound in this invention may be conducted under the conditions such as appropriate ph and temperature and within the control ranges thereof , depending on a target nucleoside , a 1 - phosphorylated saccharide derivative and a base as substrates , a nucleoside phosphorylase or a microorganism exhibiting the activity of the enzyme as a reaction catalyst , and the type and the properties of a metal salt added for removing phosphoric acid from the reaction system ; generally at ph 5 to 10 and a temperature of 10 to 60 ° c . if ph is not within the control range , a reaction inversion rate may be reduced due to , for example , poor stability of a target product or substrate , reduction in enzyme activity and failure to forming a water - insoluble salt with phosphoric acid . if ph varies in the course of the reaction , an acid such as hydrochloric acid and sulfuric acid or an alkali such as sodium hydroxide and potassium hydroxide may be , when necessary , added at an appropriate timing . the concentrations of a 1 - phosphorylated saccharide derivative and a base are suitably about 0 . 1 to 1000 mm . in terms of a molar ratio between them , a molar ratio of a base to a 1 - phosphorylated saccharide derivative or its salt may be 1 to 10 , preferably 0 . 95 or less in the light of a reaction inversion rate . a metal salt capable of forming a water - insoluble salt with phosphoric acid added may be added in a molar ratio of 0 . 1 to 10 , more preferably 0 . 5 to 5 to a 1 - phosphorylated saccharide derivative used in the reaction . there are no restrictions to an addition procedure of the salt , and it may be added in one portion or portionwise during the reaction . this invention basically uses water as a solvent , but an organic solvent such as an alcohol and dimethylsulfoxide used in a common enzyme reaction may be , if necessary , added in an appropriate amount . in a reaction with a higher concentration , a base as a substrate or a nucleoside as a product may be not be completely dissolved in the reaction solution . this invention may be also applied to such a case . a nucleoside compound produced as described above may be isolated by a common procedure such as concentration , crystallization , dissolution , electrodialysis and adsorption and desorption using an ion - exchange resin or charcoal . this invention will be more specifically described with reference to , but not limited to , examples . to a mixture of 1 . 18 g of orthophosphoric acid in 51 ml of acetonitrile were added 2 . 3 g of tri - n - butylamine and 5 . 07 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . after one hour , to the mixture was added 5 . 07 g of 3 , 5 - o - bis ( 4 - chlorobenzoyl )- 2 - deoxy - α - d - ribosyl chloride ( purity : 85 %), and the mixture was stirred for one hour to give a solution of a mixture of the title compounds ( 18 ) and ( 19 ) [( 18 ): ( 19 )= 3 : 5 , α - form / β - form of compound ( 18 )= 5 / 2 ] in acetonitrile . for preparing a sample for analysis , these compounds were converted into cyclohexylamine salts , which were then purified by silica gel column chromatography to provide two anomer isomers ( 19a ) and ( 19b ) of the title compound ( 19 ) from a fraction eluted with methanol - ethyl acetate ( 1 : 10 ). 1 h nmr ( cdcl 3 , 270 mhz ) d : 8 . 0 - 7 . 8 ( m , 8h ), 7 . 4 - 7 . 2 ( m , 8h ), 6 . 06 ( m , 1 . 2h ), 5 . 98 ( m , 0 . 8h ), 5 . 56 ( m , 1 . 2h ), 5 . 41 ( m , 0 . 8h ), 4 . 7 - 4 . 3 ( m , 6h ), 2 . 6 - 2 . 4 ( m , 1h ), 2 . 75 - 2 . 6 ( m , 2h ), 2 . 5 - 2 . 3 ( m , 2h ), 2 . 2 - 1 . 9 ( m , 2h ), 1 . 8 - 1 . 6 ( m , 2h ), 1 . 6 - 0 . 9 ( m , 8h ); ms ( apci ) m / z 883 ( m - h ). 1 h nmr ( cdcl 3 , 270 mhz ) d : 8 . 0 - 7 . 8 ( m , 8h ), 7 . 4 - 7 . 2 ( m , 8h ), 6 . 1 - 5 . 9 ( m , 2h ), 5 . 55 ( m , 0 . 67h ), 5 . 39 ( m , 1 . 33h ), 4 . 7 - 4 . 3 ( m , 6h ), 3 . 1 - 2 . 85 ( m , 1h ), 2 . 75 - 2 . 4 ( m , 2h ), 2 . 32 ( m , 2h ), 2 . 2 - 1 . 9 ( m , 2h ), 1 . 8 - 1 . 6 ( m , 2h ), 1 . 6 - 0 . 9 ( m , 8h ); ms ( apci ) m / z 883 ( m - h ). to a mixture of 1 . 11 g of orthophosphoric acid in 49 ml of 2 - butanone were added 2 . 11 g of tri - n - butylamine and 4 . 9 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . to the mixture was added 4 . 9 g of 3 , 5 - o - bis ( 4 - chlorobenzoyl )- 2 - deoxy - α - d - ribosyl chloride ( purity : 85 %), and the mixture was stirred for 10 min to give a solution of a mixture of the title compounds ( 18 ) and ( 19 ) [( 18 ) ( 19 )= 1 : 4 , α - form / β - form of compound ( 18 )= 7 / 10 ] in 2 - butanone . to a mixture of 136 . 8 g of orthophosphoric acid in 2 l of 2 - butanone were added 90 . 6 g of tri - n - butylamine and 200 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . after stirring for one hour , to the mixture was added 200 g of 3 , 5 - o - bis ( 4 - chlorobenzoyl )- 2 - deoxy - α - d - ribosyl chloride ( purity : 85 %), and the mixture was stirred for 2 hours to give a solution of a mixture of the title compounds ( 18 ) and ( 19 ) [( 18 ): ( 19 )= 5 : 4 , α - form / β - form of compound ( 18 )= 5 / 2 ] in 2 - butanone . the acetonitrile solution prepared in example 1 was cooled to 5 ° c . with stirring , and 2 . 29 g of orthophosphoric acid was added to the mixture . after stirring for 3 hours , crystallization was initiated and then the mixture became a thick suspension . after 5 hours , the ratio of α - form / β - form of the title compound ( 18 ) in the reaction suspension was 10 / 1 . the crystals were collected as a mixture with molecular sieves . the solid was dissolved in 100 ml of methanol and the mixture was again filtrated to remove molecular sieves . hplc assay showed that 3 . 68 g of the title compound ( 18a ) was contained in the methanol solution ( yield : 74 . 6 % after reduction from the purity of the starting material ) without the β - form on hplc . the 2 - butanone solution prepared in example 2 was cooled to 5 ° c . with stirring , and 2 . 2 g of orthophosphoric acid was added to the solution . after stirring for 1 hour , precipitation of crystals initiated and then a thick suspension was obtained . after 20 hours , the ratio of α - form / β - form for compound ( 18a ) in the reaction suspension was 8 : 1 . to the suspension was added 6 . 33 g of tri - n - butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration . to the filtrate was added 250 ml of toluene , and the solution was washed with 55 ml of water . the organic layer was ice - cooled . to the mixture was added 2 . 32 g of cyclohexylamine for crystallization with stirring . after 1 hour , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 3 . 19 g of a dicyclohexylamine salt of compound ( 16a ) as a colorless powder ( yield : 64 . 7 % after reduction from the purity of the starting material ; α - form : β - form = 97 . 5 : 2 . 5 ). 1 h nmr ( dmso - d 6 , 270 mhz ) d : 8 . 00 ( d , j = 8 . 6 hz , 2h ), 7 . 96 ( d , j = 8 . 6 hz , 2h ), 7 . 58 ( d , j = 8 . 6 hz , 2h ), 7 . 58 ( d , j = 8 . 6 hz , 2h ), 5 . 82 ( dd , j = 5 . 3 , 5 . 3 hz , 1h ), 5 . 36 ( d , j = 8 . 6 hz , 1h ), 4 . 6 - 4 . 3 ( m , 3h ), 4 . 7 - 3 . 5 ( br , 6h ), 2 . 7 - 2 . 6 ( m , 2h ), 2 . 55 - 2 . 4 ( m , 1h ), 2 . 25 ( d , j = 4 . 2 hz , 1h ), 1 . 85 - 1 . 75 ( m , 4h ), 1 . 7 - 1 . 6 ( m , 4h ), 1 . 55 - 1 . 45 ( m , 2h ), 1 . 25 - 0 . 9 ( m , 10h ); ms ( apci ) m / z 590 ( m + c 6 h 14 n ). the 2 - butanone solution prepared in example 3 was cooled to 5 ° c . with stirring . after stirring for 1 hour , precipitation of crystals initiated and then a thick suspension was obtained . after 23 hours , the ratio of α - form / β - form for compound ( 18a ) in the reaction suspension was 7 : 1 . to the suspension was added 259 g of tri - n - butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration . the filtrate was washed with 2 . 2 l of water and the aqueous layer was extracted with 1 l of toluene . the combined organic layer was ice - cooled . to the mixture was added 87 . 5 g of cyclohexylamine for crystallization with stirring . after 1 hour , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 213 g of a dicyclohexylamine salt of compound ( 16a ) as a colorless powder ( yield : 78 . 1 % after reduction from the purity of the starting material ; α - form : β - form = 96 . 9 : 3 . 1 ). to the methanol solution prepared in example 4 was added 20 ml of an aqueous solution of ammonium hydroxide , and the mixture was stirred at room temperature . after stirring for 28 hours , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 589 mg of an ammonium salt of compound ( 20 ) as a colorless powder ( yield : 21 . 1 % without the β - form on hplc ). compound ( 18a ) prepared in example 6 was suspended in a mixture of 2 . 3 l of methanol and 450 ml of an aqueous ammonium hydroxide solution , and the mixture was stirred at room temperature . after stirring for 28 hours , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 62 . 0 g of an ammonium salt of compound ( 20 ) as a colorless powder ( yield : 81 . 0 % without the β - form on hplc ). 1 h nmr ( d 2 o , 270 mhz ) d : 5 . 56 ( s , 1h ), 4 . 03 ( m , 2h ), 3 . 52 ( dd , j = 3 . 3 , 12 . 2 hz , 1h ), 3 . 41 ( dd , j = 5 . 3 , 12 . 2 hz , 1h ), 2 . 17 ( m , 1h ), 1 . 87 ( d , j = 13 . 9 hz , 1h ); ms ( apci ) m / z : 213 ( m - h ). to a mixture of 3 . 32 g of orthophosphoric acid in 67 ml of methyl isobutyl ketone were added 2 . 11 g of tri - n - butylamine and 6 . 6 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . to the mixture was added 6 . 66 g of 2 , 3 , 5 - o - tris ( 4 - chlorobenzoyl )- α - d - ribosyl chloride . after 1 hour , precipitation of crystals initiated and then a thick suspension was provided . after 10 hours , the ratio of α - form / β - form for compound ( 19 ) in the reaction suspension was 10 : 1 . to the suspension was added 6 . 33 g of tri - n - butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration . the filtrate was washed with 55 ml of water . the organic layer was ice - cooled . to the mixture was added 2 . 4 g of cyclohexylamine for crystallization with stirring . after 1 hour , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 7 . 02 g of a dicyclohexylamine salt of compound ( 21 ) as a colorless powder ( yield : 73 . 0 %; α - form : β - form = 99 : 1 ). 1 h nmr ( dmso - d 6 , 270 mhz ) d : 8 . 2 - 7 . 8 ( m , 6h ), 7 . 6 - 7 . 4 ( m , 6h ), 5 . 9 - 5 . 7 ( m , 1h ), 5 . 6 - 5 . 4 ( m , 3h ), 4 . 6 - 4 . 3 ( m , 1h ), 4 . 7 - 3 . 5 ( br , 6h ), 2 . 7 - 2 . 6 ( m , 2h ), 1 . 9 - 1 . 7 ( m , 4h ), 1 . 7 - 1 . 6 ( m , 4h ), 1 . 55 - 1 . 4 ( m , 2h ), 1 . 3 - 0 . 9 ( m , 10h ); ms ( apci ) m / z 745 ( m + c 6 h 14 n ). compound ( 21 ) prepared in example 9 was suspended in a mixture of 105 ml of methanol and 21 ml of an aqueous ammonium hydroxide solution , and the mixture was stirred at room temperature . after stirring for 32 hours , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 1 . 90 g of an ammonium salt of compound ( 22 ) as a colorless powder ( yield : 86 . 0 % without the β - form on hplc ). 1 h nmr ( d 2 o , 270 mhz ) d : 5 . 6 ( m , 1h ), 4 . 2 ( m , 1h ), 4 . 1 - 4 . 0 ( m , 2h ), 3 . 75 ( m , 1h ), 3 . 7 ( m , 1h ); ms ( apci ) m / z : 229 ( m - h ). to a mixture of 3 . 5 g of orthophosphoric acid in 33 ml of acetonitrile were added 2 . 2 g of tri - n - butylamine and 3 . 3 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . to the mixture was added 3 . 28 g of 5 - o -( 4 - chlorobenzoyl )- 2 , 3 - dideoxy - α - d - ribosyl chloride . after 1 hour , precipitation of crystals initiated and then a thick suspension was provided . after 20 hours , the ratio of α - form / β - form for compound ( 23 ) in the reaction suspension was 10 : 1 . to the suspension was added 6 . 5 g of tri - n - butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration . the filtrate was diluted with 70 ml of toluene and then washed with 55 ml of water . the organic layer was ice - cooled . to the mixture was added 2 . 5 g of cyclohexylamine for crystallization with stirring . after 1 hour , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 4 . 56 g of a dicyclohexylamine salt of compound ( 23 ) as a colorless powder ( yield : 71 . 5 %; α - form : β - form = 97 : 3 ). 1 h nmr ( dmso - d 6 , 270 mhz ) d : 8 . 2 - 7 . 8 ( m , 2h ), 7 . 6 - 7 . 4 ( m , 2h ), 5 . 9 - 5 . 7 ( m , 1h ), 5 . 6 - 5 . 4 ( m , 1h ), 4 . 6 - 4 . 3 ( m , 1h ), 4 . 7 - 3 . 5 ( br , 6h ), 2 . 7 - 2 . 6 ( m , 2h ), 1 . 9 - 1 . 7 ( m , 8h ), 1 . 7 - 1 . 6 ( m , 4h ), 1 . 55 - 1 . 4 ( m , 2h ), 1 . 3 - 0 . 9 ( m , 10h ); ms ( apci ) m / z 374 ( m + c 6 h 14 n ). compound ( 23 ) prepared in example 11 was suspended in a mixture of 46 ml of methanol and 10 ml of an aqueous ammonium hydroxide solution , and the mixture was stirred at room temperature . after stirring for 30 hours , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 1 . 68 g of an ammonium salt of compound ( 24 ) as a colorless powder ( yield : 85 . 0 % without the β - form on hplc ). 1 h nmr ( d 2 o , 270 mhz ) d : 5 . 2 ( m , 1h ), 4 . 1 - 3 . 9 ( m , 1h ), 3 . 6 - 3 . 3 ( m , 2h ), 2 . 1 - 2 . 3 ( m , 2h ), 1 . 9 - 1 . 7 ( m , 2h ); ms ( apci ) m / z : 197 ( m - h ). to a mixture of 3 . 3 g of orthophosphoric acid in 67 ml of methyl isobutyl ketone were added 2 . 1 g of tri - n - butylamine and 6 . 6 g of molecular sieves 4a , and the mixture was cooled to 5 ° c . with stirring . to the mixture was added 6 . 6 g of 2 , 3 , 5 - o - tris ( 4 - chlorobenzoyl )- α - d - arabinofuranosyl chloride . after 1 hour , precipitation of crystals initiated and then a thick suspension was provided . after 8 hours , the ratio of α - form / β - form for compound ( 25 ) in the reaction suspension was 10 : 1 . to the suspension was added 6 . 3 g of tri - n - butylamine to dissolve the precipitated crystals and molecular sieves were removed by filtration . the filtrate was washed with 55 ml of water . the organic layer was ice - cooled . to the mixture was added 2 . 4 g of cyclohexylamine for crystallization with stirring . after 1 hour , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 6 . 72 g of a dicyclohexylamine salt of compound ( 25 ) as a colorless powder ( yield : 70 . 5 %; α - form : β - form = 99 : 1 ). compound ( 25 ) prepared in example 13 was suspended in a mixture of 94 ml of methanol and 18 ml of an aqueous ammonium hydroxide solution , and the mixture was stirred at room temperature . after stirring for 48 hours , the precipitated crystals were collected by filtration and dried in vacuo at room temperature to provide 1 . 72 g of an ammonium salt of compound ( 26 ) as a colorless powder ( yield : 82 . 0 % without the β - form on hplc ). 1 h nmr ( d 2 o , 270 mhz ) d : 5 . 3 ( m , 1h ), 3 . 95 - 3 . 3 ( m , 5h ); ms ( apci ) m / z : 229 ( m - h ). to a solution of 1 . 06 g of ( 2r )- 2 - benzyloxymethyl - 4 -( r , s )- acetoxy - 1 , 3 - dioxorane in 12 ml of ether under ice - cooling was added 4 ml of a 4n solution of hydrochloric acid in dioxane . after stirring 3 . 5 hours , the mixture was warmed to room temperature . after removing the solvent by concentration , the residue was further subject to azeotropy with toluene to give 500 mg of ( 2r )- 2 - benzyloxymethyl - 1 , 3 - dioxoranyl chloride as a colorless and transparent oil . to 1 . 1 ml of acetonitrile were sequentially added 0 . 27 g of orthophosphoric acid , 0 . 66 ml of tri - n - butylamine and 0 . 23 g of molecular sieves 4a , and the mixture was stirred for 1 . 5 hours . to the suspension under ice - cooling was added 0 . 27 g of the previous oil , and the mixture was stirred under ice - cooling for 5 . 5 hours . to the mixture was added 0 . 6 ml of tri - n - butylamine . after stirring for 30 min , the mixture was diluted with toluene and extracted with water . the aqueous layer was extracted with n - butanol and then concentrated . the concentrate was dissolved in toluene , and to the solution was added cyclohexylamine to give a cyclohexylamine salt of compound ( 27 ) as a white solid . 1 h - nmr ( d 2 o ) δ : 0 . 98 - 1 . 10 ( 2h , m ), 1 . 14 - 1 . 23 ( 6h , m ), 1 . 47 - 1 . 51 ( 2h , m ), 1 . 61 - 1 . 64 ( 4h , m ), 1 . 78 - 1 . 83 ( 4h , m ), 2 . 94 - 3 . 00 ( 2h , m ), 3 . 46 - 3 . 60 ( 2h , m ), 3 . 72 - 3 . 79 ( 1h , m ), 3 . 92 - 4 . 00 ( 1h , m ), 4 . 41 - 4 . 51 ( 2h , m ), 5 . 01 - 5 . 03 and 5 . 22 - 5 . 24 ( total 1h , m ), 5 . 64 - 5 . 72 ( total 1h , m ), 7 . 24 - 7 . 30 ( 5h , m ); ms ( apci ) m / z : 390 ( m + c 6 h 14 n ) + . in 10 ml of methanol was dissolved 0 . 2 g of compound ( 27 ) prepared in example 15 . the solution was subject to hydrogenation under an ambient pressure using 0 . 11 g of 10 % pd / c as a catalyst . after removing the catalyst by filtration , the filtrate was concentrated to give a cyclohexylamine of compound ( 28 ). 1 h - nmr ( d 2 o ) δ : 0 . 99 - 1 . 06 ( 2h , m ), 1 . 10 - 1 . 24 ( 6h , m ), 1 . 47 - 1 . 50 ( 2h , m ), 1 . 62 - 1 . 66 ( 4h , m ), 1 . 80 - 1 . 85 ( 4h , m ), 1 . 96 - 3 . 02 ( 2h , m ), 3 . 51 - 3 . 57 ( 2h , m ), 3 . 72 - 3 . 79 ( 1h , m ), 3 . 93 - 4 . 00 ( 1h , m ), 4 . 99 - 5 . 01 and 5 . 13 - 5 . 15 ( total 1h , m ), 5 . 64 - 5 . 67 and 5 . 70 - 5 . 73 ( total 1h , m ); ms ( apci ) m / z : 199 ( m - h ) − . seventy mg of molecular sieves 4a was added to a stirred mixture of 62 mg of orthophosphoric acid , 52 μl of tri - n - butylamine and 0 . 7 ml of acetonitrile at room temperature , and the mixture was stirred in an ice - bath . to the mixture was added 70 mg of 2 , 3 - dideoxy - 3 - fluoro - 5 - o -( 4 - phenylbenzoyl )- d - erythropentofuranosyl chloride , and the mixture was reacted at the same temperature for 1 day . then , to the mixture were added 156 μl of tri - n - butylamine and then deionized water . the mixture was extracted with toluene three times . to the organic layer was added 48 μl of cyclohexylamine and the mixture was stirred for 30 min . the mixture was concentrated in vacuo , and acetone was added to form a precipitate , which was collected by filtration . the residue was washed with chloroform and dried in vacuo at room temperature to give a dicyclohexylamine of compound ( 29 ) as a white solid . 1 h - nmr ( cd 3 od ) δ : 1 . 1 - 1 . 4 ( 10h , m ), 1 . 65 ( 2h , m ), 1 . 89 ( 4h , m ), 1 . 96 ( 4h , m ), 2 . 3 - 2 . 5 ( 2h , m ), 2 . 91 ( 2h , m ), 4 . 5 ( 2h , m ), 4 . 6 - 4 . 8 ( 1h , m ), 5 . 1 - 5 . 3 ( 1h , m ), 5 . 97 ( 1h , m ), 7 . 41 ( 1h , m ), 7 . 47 ( 2h , m ), 7 . 68 ( 2h , m ), 7 . 75 ( 2h , m ), 8 . 08 ( 2h , m ); ms ( apci ) m / z : 496 ( m + c 6 h 14 n ) + . to a solution of 21 mg of compound ( 29 ) prepared in example 17 in 1 ml of methanol was added 20 μl of cyclohexylamine and the mixture was reacted for 2 weeks . the mixture was concentrated in vacuo and diethyl ether was added . the mixture was filtered , and the solid was dried in vacuo to give 12 mg of a dicyclohexylamine salt of the title compound as a white solid . 1 h - nmr ( cd 3 od ) δ : 1 . 1 - 1 . 4 ( 10h , m ), 1 . 66 ( 2h , m ), 1 . 79 ( 4h , m ), 1 . 94 ( 4h , m ), 2 . 3 - 2 . 4 ( 2h , m ), 2 . 88 ( 2h , m ), 3 . 59 ( 2h , m ), 4 . 3 - 4 . 4 ( 1h , m ), 5 . 11 ( 0 . 5h , m ; the other 0 . 5h was undistinguishable because it was behind the peak of water ), 5 . 89 ( 1h , m ); ms ( apci ) m / z : 215 ( m - h ) − . at room temperature 0 . 86 g of molecular sieves 4a was added to a stirred mixture of 759 mg of orthophosphoric acid , 646 μl of tri - n - butylamine and 8 . 6 ml of acetonitrile at room temperature , and the mixture was stirred in an ice - bath . to the mixture was added 864 mg of 2 , 3 - dideoxy - 3 - fluoro - 5 - o -( 4 - phenylbenzoyl )- d - erythropentofuranosyl chloride , and the mixture was reacted at the same temperature for 1 day . then , to the mixture were added 1 . 94 ml of tri - n - butylamine and then deionized water . the mixture was extracted with toluene three times and washed with purified water five times . the organic layer was separated . to the organic layer was added 590 μl of cyclohexylamine and the mixture was stirred for 30 min . the mixture was concentrated in vacuo . after addition of acetone , the mixture was stirred and filtrated . the residue was further washed with isopropyl ether and dried in vacuo at room temperature to give compound ( 31 ) as a white solid . α - form : β - form 66 : 34 . 1 h - nmr ( cd 3 od ) δ : 1 . 1 - 1 . 4 ppm ( 10h , m ), 1 . 66 ( 2h , m ), 1 . 78 ( 4h , m ), 1 . 98 ( 4h , m ), 2 . 3 - 2 . 6 ( 2h , m ), 2 . 89 ( 2h , m ), 4 . 44 & amp ; 4 . 46 ( α & amp ; β , 2h ), 4 . 6 - 4 . 8 ( 1h , m ), 5 . 1 - 5 . 3 & amp ; 5 . 3 - 5 . 4 ( α & amp ; β , 1h , m ), 5 . 97 & amp ; 6 . 00 ( α & amp ; β , 1h , m ), 7 . 40 ( 1h , m ), 7 . 47 ( 2h , m ), 7 . 68 ( 2h , m ), 7 . 75 ( 2h , m ), 8 . 07 ( 1h , m ), 8 . 13 ( 1h , m ). to a solution of 0 . 29 g of compound ( 31 ) prepared in example 19 in 15 ml of methanol was added 279 μl of cyclohexylamine and the mixture was reacted for 1 week . the mixture was concentrated in vacuo and diethyl ether was added . after stirring , the mixture was filtered , and the solid was dried in vacuo to give 185 mg of a dicyclohexylamine salt of compound ( 32 ) as a white solid . α - form : β - form = 66 : 34 . 1 h - nmr ( cd 3 od ) δ : 1 . 1 - 1 . 4 ppm ( 10h , m ), 1 . 67 ( 2h , m ), 1 . 79 ( 4h , m ), 2 . 2 - 2 . 4 ( 2h , m ), 2 . 94 ( 2h , m ), 3 . 59 & amp ; 3 . 62 ( α & amp ; β , 2h , m ), 3 . 3 - 3 . 4 ( 2h , m ), 5 . 10 & amp ; 5 . 1 - 5 . 24 ( α & amp ; β , 0 . 5h & amp ; 1h , m , 0 . 5h of the α - form was undistinguishable because the signal was behind the peak of water ), 5 . 88 & amp ; 5 . 93 ( α & amp ; β , 1h , m ). to 2 . 84 g of 1 , 3 , 5 - o - tribenzoyl - 2 - o - methyl - α - d - ribose was added 14 . 5 ml of a 4n solution of hydrochloric acid in dioxane , and the mixture was stirred under ice - cooling . after stirring 2 . 5 hours , 10 ml of a 4n solution of hydrochloric acid in dioxane was further added , and the mixture stirred for 1 hour . after evaporating the solvent , the residue was further subject to azeotropy with 10 ml of dioxane twice to give 3 , 5 - o - dibenzoyl - 2 - o - methylribosyl - 1 - chloride . separately , 2 . 98 g of 98 % phosphoric acid was dissolved in 15 ml of 4 - methyl - 2 - pentanone and after adding 2 . 8 g of molecular sieves 4a , the mixture was stirred for 30 min . to the mixture were added 1 . 42 ml of tri - n - butylamine and then a solution of the previous 3 , 5 - o - dibenzoyl - 2 - o - methylribosyl - 1 - chloride in 10 ml of 4 - methyl - 2 - pentanone . after reacting the mixture at room temperature for 20 hours , it was neutralized with 7 . 1 ml of tri - n - butylamine . after removing the molecular sieves by filtration , the filtrate was washed with 20 ml of water three times . the organic layer was evaporated and purified by silica gel column chromatography to give 950 mg of compound ( 33 ). ms ( apci ) m / z : 451 ( m - h ) − ; ir ( kbr ) cm − 1 : 3448 , 2963 , 1721 , 1453 , 1278 , 1111 , 976 , 711 , 558 . to 850 mg of compound ( 33 ) prepared in example 21 was 20 ml of 14 % ammonia - methanol , and the mixture was reacted at room temperature for 20 hours . after evaporation of the solvent , diisopropyl ether was added to form a sludge and the crystalline powder was collected by filtration . the powder was dissolved in methanol . to the solution was added cyclohexylamine , and the mixture was stirred . after evaporating methanol , diisopropyl ether was added to the residue to form a sludge . the crystalline powder was collected by filtration and washed with diisopropyl ether . the desired product was extracted with water and the aqueous layer was washed with 4 - methyl - 2 - pentanone twice . the aqueous layer was concentrated and to the layer was added diisopropyl ether to form a sludge . after filtration , the crystals were washed with diisopropyl ether to give 120 mg of a dicyclohexylamine salt of compound ( 34 ). 1 h - nmr ( d 2 o ) δ : 3 . 37 ( s , 3h ), 3 . 49 ( dd , 1h , j = 4 . 9 hz , 12 . 7 hz ), 3 . 62 ( d , 1h , j = 4 . 9 hz ), 3 . 69 ( dd , 1h , j = 2 . 7 hz , 12 . 7 hz ), 3 . 74 - 3 . 78 ( m , 1h ), 4 . 28 ( dd , 1h , j = 4 . 6 hz , 7 . 8 hz ), 5 . 39 ( d , 1h , j = 5 . 9 hz ); ms ( apci ) m / z : 243 ( m - h ) − . to a mixture of 6 . 92 g of orthophosphoric acid in 80 ml of acetonitrile were added 5 . 51 ml of tri - n - butylamine and 10 g of molecular sieves 4a . the mixture was stirred at room temperature for 5 hours and allowed to stand overnight . after cooling to − 7 ° c ., to the mixture was added 10 g of 3 , 5 - o - bis ( 4 - chlorobenzoyl )- 2 - deoxy - α - d - ribosyl chloride ( purity : 85 %). the mixture was stirred for 9 hours and allowed to stand at − 15 ° c . overnight . after adding 16 . 5 ml of tri - n - butylamine , the molecular sieves were removed by filtration . the filtrate was concentrated and the residue was dissolved in 4 - methyl - 2 - pentanone and washed with water . the organic layer was ice - cooled and 5 . 66 ml of cyclohexylamine was added with stirring for crystallization . after 1 . 5 hours , the precipitated crystals were filtered and dried in vacuo at room temperature to give 13 . 5 g of a dicyclohexylamine salt of compound ( 18a ). α - form : β - form = 98 . 8 : 1 . 2 ). to a solution of 7 . 05 g of the compound obtained in example 23 in methanol was added 2 . 92 ml of cyclohexylamine , and the mixture was stirred at room temperature . after stirring 72 hours , the mixture was concentrated and to the residue was added ethanol to provide a suspension which was then stirred . after collecting the precipitated crystals , they were dried i vacuo at room temperature to give 3 . 87 g of a dicylcohexylamine salt of compound ( 20 ) ( without the β - form on nmr ). 1 h nmr ( d 2 o ) d : 5 . 57 ( dd , j = 5 . 1 , 6 . 1 hz , 1h ), 4 . 03 ( m , 2h ), 3 . 54 ( ddd , j = 1 . 2 , 2 . 2 , 12 . 2 hz , 1h ), 3 . 42 ( ddd , j = 1 . 2 , 5 . 1 , 12 . 2 hz , 1h ), 3 . 18 - 2 . 94 ( m , 2h ), 2 . 17 ( m , 1h ), 1 . 90 ( d , j = 1 . 2 , 12 . 8 hz , 1h ), 1 . 8 - 1 . 45 ( m , 10h ), 1 . 25 - 0 . 9 ( m , 12h ). anal . calcd . for c 5 h 9 o 7 p . c 12 h 28 n 2 , c , 49 . 50 %; h : 9 . 04 %; n , 6 . 79 %; p : 7 . 51 %, fifty ml of an lb medium was inoculated with escherichia coli k - 12 / xl - 10 strain ( stratagene inc .) and it was cultured at 37 ° c . overnight . after collection , the bacteria was lysed with a lysis solution containing 1 mg / ml of lysozyme . the lysis solution was treated with phenol and dna was precipitated as usual by ethanol precipitation . the dna precipitate was collected with a glass rod and washed to prepare an e . coli chromosome dna . oligonucletides of seq id nos . 1 and 2 designed based on the sequence a known deod gene in escherichia coli ( genbank accession . no . ae000508 with a coding region of base numbers 11531 to 12250 ) were used as primers for pcr . these primers have restriction enzyme recognition sequences for ecori and hind iii near 5 ′- and 3 ′- ends , respectively . using 0 . 1 ml of a pcr reaction solution containing 6 ng / μl of the above e . coli chromosome dna completely digested by restriction enzyme hind iii and the primers ( each at 3 μm ), pcr was conducted by 30 cycles under the conditions of denaturation : 96 ° c ., 1 min ; annealing : 55 ° c ., 1 min ; elongation : 74 ° c ., 1 min per a cycle . the above reaction product and a plasmid puc18 ( takara shuzo co . ltd .) were digested by ecori and hind iii and ligated using ligation - high ( toyobo co . ltd .). the recombinant plasmid obtained was used to transform escherichia coli dh5α . the transformed strain was cultured in an lb agar medium containing 50 μg / ml of ampicillin and x - gal ( 5 - bromo - 4 - chloro - 3 - indolyl - β - galactoside ) to provide an am - resistant transformant as a white colony . a plasmid was extracted from the transformant thus obtained and the plasmid in which a desired dna fragment had been inserted was designated as puc - pnp73 . the transformant thus obtained was designated as escherichia coli mt - 10905 . escherichia coli mt - 10905 was cultured by shaking at 37 ° c . overnight in 100 ml of an lb medium containing 50 μg / ml of am . the culture medium was centrifuged at 13 , 000 rpm for 10 min to collect the bacteria . the bacteria were suspended in 10 ml of 10 mm tris - hydrochloride buffer ( ph 8 . 0 ) and ultrasonicated to give a homogenate which was then used as an enzyme source . reaction solutions were prepared by adding calcium chloride ( waco pure chemicals , extra pure grade ) at different concentrations to a mixture of 2 . 5 mm 2 - deoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 8 , 2 . 5 mm adenine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain and 10 mm tris - hydrochloride buffer ( ph 7 . 4 ). one ml of a reaction solution was reacted at 30 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis described below for a post - reaction solution showed a peak completely identical to the peak of 2 ′- deoxyadenosine ( wako pure chemicals , extra pure grade ) in all the post - reaction solutions . table 1 shows the calculation results of a reaction inversion rate after determining a concentration of 2 ′- deoxyadenosine in a post - reaction solution . a reaction was conducted as described in example 25 except that aluminum chloride was added in place of calcium chloride . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solutions as described in example 25 showed a peak completely identical to the peak of 2 ′- deoxyadenosine ( wako pure chemicals , extra pure grade ) in all the post - reaction solutions . table 2 shows the calculation results of a reaction inversion rate after determining a concentration of 2 ′- deoxyadenosine in a post - reaction solution . a reaction was conducted as described in example 25 except that 10 mm of barium chloride was added in place of calcium chloride . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solutions as described in example 25 showed a peak completely identical to the peak of 2 ′- deoxyadenosine ( wako pure chemicals , extra pure grade ) in the post - reaction solutions . a reaction inversion rate after determining a concentration of 2 ′- deoxyadenosine in a post - reaction solution was calculated to be 92 . 4 %. one ml of a reaction solution consisting of 2 . 5 mm 2 - deoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 8 , 2 . 5 mm thymine ( wako pure chemicals , extra pure grade ), 12 units / ml thymidine phosphorylase ( sigma ), 0 mm or 10 mm calcium nitrate ( wako pure chemicals , extra pure grade ) and 10 mm tris - hydrochloride buffer ( ph 7 . 4 ) was reacted at 30 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solutions as described in example 25 showed a peak completely identical to the peak of thymidine ( wako pure chemicals , extra pure grade ) in the post - reaction solution . table 3 shows the calculation results of a reaction inversion rate after determining a concentration of thymidine in the post - reaction solution . one ml of a reaction solution consisting of 100 mm 2 - deoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 8 , 100 mm adenine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 , 0 to 150 mm calcium chloride ( waco pure chemicals , extra pure grade ) and 100 mm tris - hydrochloride buffer ( ph 8 . 0 ) was reacted at 50 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solutions as described in example 25 showed a peak completely identical to the peak of 2 - deoxyadenosine ( wako pure chemicals , extra pure grade ) in the post - reaction solutions . table 4 shows the calculation results of determining a concentration of 2 ′- deoxyadenosine in a post - reaction solution . one ml of a reaction solution consisting of 100 mm 2 - deoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 8 , 100 mm guanine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 , 0 mm or 150 mm calcium chloride ( waco pure chemicals , extra pure grade ) and 100 mm tris - hydrochloride buffer ( ph 8 . 0 ) was reacted at 50 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solution as described in example 25 showed a peak completely identical to the peak of 2 - deoxyguanosine ( wako pure chemicals , extra pure grade ) in the post - reaction solution . table 5 shows the calculation results of determining a concentration of 2 ′- deoxyguanosine in the post - reaction solution . one ml of a reaction solution consisting of 100 mm α - d - ribose - 1 - phosphate diammonium salt prepared in example 10 , 100 mm adenine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 , 0 mm or 150 mm calcium chloride ( waco pure chemicals , extra pure grade ) and 100 mm tris - hydrochloride buffer ( ph 8 . 0 ) was reacted at 50 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solution as described in example 25 showed a peak completely identical to the peak of adenosine ( wako pure chemicals , extra pure grade ) in the post - reaction solution . table 6 shows the calculation results of determining a concentration of adenosine in the post - reaction solution . one ml of a reaction solution consisting of 100 mm 2 , 3 - dideoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 12 , 100 mm adenine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 , 0 mm or 150 mm calcium chloride ( waco pure chemicals , extra pure grade ) and 100 mm tris - hydrochloride buffer ( ph 8 . 0 ) was reacted at 50 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solution as described in example 25 showed a peak completely identical to the peak of 2 ′, 3 ′- dideoxyadenosine ( sigma , extra pure grade ) in the post - reaction solution . table 7 shows the calculation results of determining a concentration of 2 ′, 3 ′- dideoxyadenosine in the post - reaction solution . one ml of a reaction solution consisting of 100 mm α - d - arabinofuranosyl - 1 - phosphate diammonium salt prepared in example 14 , 100 mm adenine ( wako pure chemicals , extra pure grade ), 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 , 0 mm or 150 mm calcium chloride ( waco pure chemicals , extra pure grade ) and 100 mm tris - hydrochloride buffer ( ph 8 . 0 ) was reacted at 50 ° c . for 24 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solution as described in example 25 showed a peak completely identical to the peak of adenine - arabinoside ( sigma , extra pure grade ) in the post - reaction solution . table 8 shows the calculation results of determining a concentration of adenine - 9 - β - d - arabinoside in the post - reaction solution . one ml of a reaction solution consisting of 10 mm 2 - deoxy - α - d - ribose - 1 - phosphate diammonium salt prepared in example 8 , 10 mm 2 - amino - 6 - chloropurine ( tokyo kasei ), 100 mm tris - hydrochloride buffer ( ph 7 . 5 ) and 50 μl of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 was reacted at 50 ° c . for 4 hours . at the end of the reaction , a white precipitate had been formed . hplc analysis for the post - reaction solution under the conditions below showed a peak of 2 - amino - 6 - chloropurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 20 . 9 % after determining the concentration of 2 - amino - 6 - chloropurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . a reaction was conducted as described in example 34 except that 2 , 6 - diaminopurine ( tokyo kasei ) was added in place of 2 - amino - 6 - chloropurine . hplc analysis for the post - reaction solution as described in example 34 showed a peak of 2 , 6 - diaminopurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 75 . 5 % after determining the concentration of 2 , 6 - diaminopurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . a reaction was conducted as described in example 34 except that 6 - mercaptopurine ( koujin ) was added in place of 2 - amino - 6 - chloropurine . hplc analysis for the post - reaction solution as described in example 34 showed a peak of 6 - mercaptopurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 57 . 2 % after determining the concentration of 6 - mercaptopurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . a reaction was conducted as described in example 34 except that 2 - amino - 6 - iodopurine was added in place of 2 - amino - 6 - chloropurine . hplc analysis for the post - reaction solution as described in example 34 showed a peak of 2 - amino - 6 - iodopurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 69 . 2 % after determining the concentration of 2 - amino - 6 - iodopurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . a reaction was conducted as described in example 34 except that 2 - acetylamino - 6 - hydroxypurine ( tokyo kasei ) was added in place of 2 - amino - 6 - chloropurine . hplc analysis for the post - reaction solution under the conditions described below showed a peak of 2 - acetylamino - 6 - hydroxypurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 48 . 7 % after determining the concentration of 2 - acetylamino - 6 - hydroxypurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . a reaction was conducted as described in example 34 except that 2 - amino - 6 - cyclopropylaminopurine was added in place of 2 - amino - 6 - chloropurine . hplc analysis for the post - reaction solution as described in example 38 showed a peak of 2 - amino - 6 - cyclopropylaminopurine - 2 ′- deoxy - β - d - riboside . a reaction inversion rate was calculated to be 87 . 6 % after determining the concentration of 2 - amino - 6 - cyclopropylaminopurine - 2 ′- deoxy - β - d - riboside in the post - reaction solution . one ml of a reaction solution consisting of 7 . 0 mm 2 , 3 - dideoxy - 3 - fluoro - d - erythropentofuranose - 1 - phosphate prepared in example 18 , 10 mm guanine ( tokyo kasei ), 100 mm tris - hydrochloride buffer ( ph 7 . 5 ) and 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 was reacted at 50 ° c . for 114 hours . hplc analysis for the post - reaction solution as described in example 34 showed a peak of 2 ′, 3 ′- dideoxy - 3 ′- fluoro - d - guanosine . a reaction inversion rate was calculated to be 47 . 7 % after determining the concentration of 2 ′, 3 ′- dideoxy - 3 ′- fluoro - d - guanosine in the post - reaction solution . one ml of a reaction solution consisting of 7 . 0 mm 2 , 3 - dideoxy - 3 - fluoro - d - erythropentofuranose - 1 - phosphate prepared in example 18 , 10 mm guanine ( tokyo kasei ), 100 mm tris - hydrochloride buffer ( ph 7 . 5 ) and 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 was reacted at 50 ° c . for 47 hours . to the solution was added calcium chloride to a final concentration of 20 mm and the mixture was reacted at 50 ° c . for additional 67 hours . hplc analysis for the post - reaction solution as described in example 34 showed a peak of 2 ′, 3 ′- dideoxy - 3 ′- fluoro - d - guanosine . a reaction inversion rate was calculated to be 84 . 4 % after determining the concentration of 2 ′, 3 ′- dideoxy - 3 ′- fluoro - d - guanosine in the post - reaction solution . one ml of a reaction solution consisting of 10 mm 6 - chloropurine ( aldrich ), 50 mm d - ribose - 1 - phosphate ( 22 ) prepared in example 10 , 0 . 1 ml of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 and 100 mm tris - hydrochloride buffer ( ph 7 . 5 ) was reacted at 50 ° c . for 20 hours . after completion of the reaction , hplc analysis for the reaction solution under the conditions described below showed a peak of the title compound . a reaction inversion rate was calculated to be 62 . 4 % after determining the concentration of 6 - chloro - 9 -( β - d - ribofuranos - 1 - yl ) purine in the post - reaction solution . one ml of a reaction solution consisting of 10 mm 2 - deoxy - α - d - ribose - 1 - phosphate ammonium salt prepared in example 8 , 10 mm 4 - azabenzimidazole ( aldrich ), 100 mm tris - hydrochloride buffer ( ph 7 . 5 ) and 50 μl of the ultrasonic enzyme homogenate from a purinenucleoside - phosphorylase producing strain prepared in example 25 was reacted at 50 ° c . for 17 hours . hplc analysis for the post - reaction solution under the conditions described below showed two peaks of the title compounds . reaction inversion rates were calculated to be 3 % and 7 . 2 % after determining the concentrations of the products in the post - reaction solution . a reaction was conducted as described in example 43 except that 8 - azaadenine ( aldrich ) was used in place of 4 - azabenzimidazole . hplc analysis for the post - reaction solution under the conditions described below showed a peak of 8 - aza - 2 ′- deoxyadenosine . a reaction inversion rate was calculated to be 4 . 8 % after determining the concentration of 8 - aza - 2 ′- deoxyadenosine in the post - reaction solution . a reaction was conducted as described in example 43 except that 8 - azaguanine ( tokyo kasei ) was used in place of 4 - azabenzimidazole . hplc analysis for the post - reaction solution as described in example 44 showed a peak of 8 - aza - 2 ′- deoxyguanosine . a reaction inversion rate was calculated to be 36 . 1 % after determining the concentration of 8 - aza - 2 ′- deoxyguanosine in the post - reaction solution . a reaction was conducted as described in example 43 except that 2 - chloro - 4 - aminopurine was used in place of 4 - azabenzimidazole . hplc analysis for the post - reaction solution under the conditions described below showed a peak of the title compound . a reaction inversion rate was calculated to be 96 % after determining the concentration of 2 - chloro - 2 ′- deoxyadenosine in the post - reaction solution . a reaction was conducted as described in example 43 except that 1 , 2 , 4 - tosyazole - 3 - carboxamide was used in place of 4 - azabenzimidazole . hplc analysis for the post - reaction solution under the conditions described below showed a peak of the title compound . a reaction inversion rate was calculated to be 69 % after determining the concentration of 1 -( β - d - ribofuranos - 1 - yl )- 1 , 3 , 4 - triazole - 3 - carboxamide in the post - reaction solution . a reaction was conducted as described in example 43 except that 5 - aminoimidazole - 4 - carboxamide was used in place of 4 - azabenzimidazole . hplc analysis for the post - reaction solution under the conditions described below showed a peak of the title compound . a reaction inversion rate was calculated to be 46 % after determining the concentration of 1 -( β - d - ribofuranos - 1 - yl )- 5 - aminoimidazole - 4 - carboxamide in the post - reaction solution . to 20 g of purified water were added 3 . 22 g of 2 - deoxyribose - 1 - phosphate di ( monocyclohexylammonium ) salt prepared in example 24 ( 7 . 72 mmol ), 1 . 11 g of guanine ( 7 . 34 mmol ) and 0 . 67 g of magnesium hydroxide ( 11 . 48 mmol ). the reaction mixture was adjusted to ph 9 with a 20 % aqueous solution of sodium hydroxide . to the mixture was added 0 . 1 ml of the above enzyme solution ( 0 . 1 ml ), and the mixture was reacted with stirring at 50 ° c . for 8 hours . hplc analysis for the reaction mixture after 8 hours indicated that the desired 2 ′- deoxyguanosine was provided with a reaction yield of 99 %. to 20 g of purified water were added 3 . 22 g of 2 - deoxyribose - 1 - phosphate di ( monocyclohexylammonium ) salt prepared in example 24 ( 7 . 72 mmol ), 1 . 01 g of adenine ( 7 . 47 mmol ) and 0 . 67 g of magnesium hydroxide ( 11 . 48 mmol ). the reaction mixture was adjusted to ph 8 . 6 with a 20 % aqueous solution of sodium hydroxide . to the mixture was added 0 . 1 ml of the above enzyme solution ( 0 . 1 ml ), and the mixture was reacted with stirring at 50 ° c . for 3 hours . hplc analysis for the reaction mixture after 8 hours indicated that the desired 2 ′- deoxyadenosine was provided with a reaction yield of 99 %. as described above , this invention is quite useful as an anomer selective process for producing a 1 - phosphorylated saccharide derivative or a nucleoside and may be expected to used in a variety of applications .