The method 1, wherein step is carried out by treating the compound of the formula in DMF in {HEAD ~ the presence} of {TAIL ~ 20 to 40 molar equivalents} of POCl3 
of
The method 1 , wherein step is carried out by treating the compound of the formula in DMF in { HEAD ~ the presence } of { TAIL ~ 20 to 40 molar equivalents } of POCl3
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH