Part A: Syntheses and reactions of 2-thiomannopyranosides. Part B: A radical cyclization/fragmentation route to oxtosyl acid A

Syntheses and reactions of 2-thiomannopyranosides have been studied. An important discovery in this area is the one pot synthesis of alpha-(1 → 2)-linked thio-mannopyranoside oligomers by a controlled oligomerization of glycal-1,2-episulfide.;In 1975, octosyl acid A and several congeners were isolated from cultures of Streptomyces cacaoi var asoerisis. They are structurally related to the antifungal ezomycins, and have been viewed as carbon analogues of 3',5'-cyclic nucleotides. An efficient 16 step synthetic approach to the carbohydrate portion of the molecule has been developed. The key step in the synthesis involves a novel radical cyclization/fragmentation, which affords the bicyclic perhydropyranofuran core.