Various 3 '-deoxythymidine analogues with an heterocyclic five-membered ring in the 3'- erythro position have been synthesized. The pyrrol-1-yl (3) and the 1, 2, 4-triazol-4-yl (5) compounds were synthesized from 1-(3-amino-2, 3-dideoxy-@-D-erythro-pentofuranosy1) thymine. The pyrazol-1-yl (16a), imidazol-l-y1 (16b), and 1, 2, 4-triazol-l-y1 (16c) derivatives were obtained by epoxide opening of the corresponding 1-(2, 3-anhydro-@-~-l~ o~~~ yl) ...