Synthesis and Properties of S,S-Diaryl Thymidine Phosphorodithioates

Abstract
Appropriately protected or unprotected S,S-diphenyl thymidine 3′- or 5′-phosphorodithioates and S,S-bis(4-methoxyphenyl) thymidine 3′- or 5′-phosphorodithioates were successfully prepared by the reaction of the thymidine derivatives with cyclohexylammonium S,S-diaryl phosphorodithioates in the presence of 2,4,6-triisopropylbenzene-sulfonyl chloride (TPS). Stabilities of the thymidylic compounds under acidic or alkaline conditions were described in detail. Several methods for the deprotection of one or both arylthio groups under neutral conditions were also described in connection with the synthesis of oligothymidylates. By the use of the bis(4-methoxyphenylthio)phosphoryl group, di- and tri-thymidylates were synthesized in high yields.