Novel 3'-C/N-substituted 2',3'-beta-D-dideoxynucleosides as potential chemotherapeutic agents. 1. Thymidine derivatives: synthesis, structure, and broad spectrum antiviral properties.

A synthetic scheme for the 3'-oxime derivatives 3E, 5E, 5Z, 7E and 7Z of 1-(2,3-dideoxy-beta-D-glycero-pentofuranosyl)thymine and for 1-(2,3-dideoxy-3-nitro-beta-D-erythro-pentofuranosyl)-thymine (10) has been developed starting from appropriately 5'-protected 3'-ketothymidine. X-ray analysis showed that 3'-N-hydroxyimino 3E and 3'-N-methoxyimino 5Z derivatives have close molecular conformations: anti about the N1-C1' bond, and gauche+ about the C4'-C5' exocyclic bond. Their sugar conformations are C1'-exo-O4'-endo and C1'-exo-C2'-endo, respectively.