Synthesis of 3'-azolyl-2',3'-dideoxyhexose nucleosides

1,8-Diazabicyclo[5.4.0]undec-7-ene salts of 2-methyl-4(5)-nitroimidazole or benzotriazole were obtained in crystalline form. Michael-type addition of these salts to (4S,5R)-(E)-4,6-di-O-acetyl-5-hydroxy-2-hexenal gave, after acetylation of the product, an isomeric mixture of acetylated 3-(azol-1-yl)-2,3-dideoxy-D-arabino-hexopyranosides and 3-(azol-1-yl)-2,3-dideoxy-D-ribo-hexofuranosides. Reaction of these peracetylated adducts with trimethylsilylated thymine in the presence of trimethylsilyl trifluoromethanesulfonate (TMS triflate) afforded the corresponding nucleosides which were deprotected by using methanolic ammonia. The nucleosides were found inactive against HIV-1 and HSV-1.