NUCLEOSIDES AND NUCLEOTIDES .120. STEREOSELECTIVE RADICAL DEOXYGENATION OF TERT-ALCOHOLS IN THE SUGAR MOIETY OF NUCLEOSIDES - SYNTHESIS OF 2',3'-DIDEOXY-2'-C-METHYL-BETA-D-THREO-PENTOFURANOSYL AND 2',3'-DIDEOXY-2'-C-ETHYNYL-BETA-D-THREO-PENTOFURANOSYL PYRIMIDINES AND ADENINE AS POTENTIAL ANTIVIRAL AND ANTITUMOR AGENTS

Radical deoxygenation of 2'-O-methoxalyl ester of the corresponding 3'-deoxy-2'-C-methyl-beta-D-threo-pentofuranosyl-pyrimidines and -adenine, which were readily obtained from the reaction of 1-(3-deoxy-beta-D-erythro-pentofuran-2-ulosyl)pyrimidines and adenine derivatives with MeMgBr, gave stereospecifically 2',3'-dideoxy-2'-C-methyl-beta-D-threo-pentofuranosyl-uracil (9a), -thymine (9b), -cytosine (9c), and -adenine (18), respectively, after deprotection. Similarly, synthesis of 2',3'-dideoxy-2'-C-ethynyl-beta-D-threo-pentofuranosyl-thymine (25) and -adenine (31) was achieved by the reaction of the corresponding ketones with LiC=CTMS, followed by radical deoxygenation of the tert-methoxaly ester. Cytotoxicity and anti-HIV activities of these nucleosides in vitro were described.