Reactions of phenyl and ethyl 2-O-sulfonyl-1-thio-alpha-D-manno- and beta-D-glucopyranosides with thionucleophiles.

Persubstituted derivatives of phenyl and ethyl 2-O-sulfonyl-1-thio-alpha-D-manno- and beta-D-glucopyranosides were synthesized and reacted either with PhSNa or with MeSNa. The phenyl-1-thio compounds afforded the dithio-1,2-cis-axial/equatorial-alpha-D-glucopyranosides or dithio-1,2-cis-equatorial/axial-beta-D-mannopyranosides by means of S(N)2 type of reactions. Starting from the ethyl-1-thio derivatives intramolecular 1,2-thio-migration took place predominantly. In the case of mannosides both nucleophilic reagents facilitate the formation of 1-SPh- or 1-SEt glycals by elimination. The formation of unsubstituted glycal could also be observed from the ethyl-1-thio derivatives, especially by using PhSNa as a nucleophile. The 1,2-dithio-glycosides are glycosyl donors affording 1,2-trans-2-thio-glycosides.