with a silylating agent and a fluoride ion catalyst cyclizing agent or, when B is a deprotonated chiral auxiliary as defined above, with a silylating agent and a salt of said chiral auxiliary, provided that where substituents A, D, Q, R, R1 and R2 include substituents selected from the group consisting of NH2, SH and OH, said substituents are suitably protected prior to {HEAD ~ reaction} with {TAIL ~ the silylating agent} 
with
with a silylating agent and a fluoride ion catalyst cyclizing agent or , when B is a deprotonated chiral auxiliary as defined above , with a silylating agent and a salt of said chiral auxiliary , provided that where substituents A , D , Q , R , R1 and R2 include substituents selected from the group consisting of NH2 , SH and OH , said substituents are suitably protected prior to { HEAD ~ reaction } with { TAIL ~ the silylating agent }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL