Synthesis of 6, 5'-Cyclo-2', 5'-dideoxypyrimidine Nucleosides (Nucleosides and Nucleotides. LXXII)

Abstract

6, 5'-Cyclo -2', 5'-dideoxyuridine and 6, 5'-cyclo-5'-deoxythymidine, pyrimidine deoxynucleosides fixed in the anti conformation, were synthesized. The key intermediate, 3'-O-acetyl-5-chloro-2', 5'-dideoxy-5'-iodouridine (12), prepared from 2'-deoxyuridine, was cyclized by treatment with tributyltin hydride to the 6, 5'-cyclo derivative (13), then dehydrochlorinated to furnish, after de-O-acetylation, 6, 5'-cyclo-2', 5'-dideoxyuridine (14). For the synthesis of 6, 5'-cyclothymidine, 3'-O- acetyl -2', 5'-dideoxy-5'-iodo-5- phenylthiomethyluridine (22) was prepared from 2'-deoxyuridine and this compound was cyclized by treatment with tributyltin hydride to yield, after de-O-acetylaion, 6, 5'-cyclo-5'-deoxythymidine (24).