The Synthesis of 6-Substituted Methyl 1-O-Acetyl-3,4-anhydro-β-D-Tagatofuranosides. Regioselective Chlorination and Thioacetylation in the Presence of an Oxiran

Abstract

Methyl 1-O-acetyl-6-S-acetyl-3,4-anhydro-6-thio-β-D-tagatofuranoside (the 1-acetate of (2)) and methyl 1-O-acetyl-3,4-anhydro-6-chloro-6-deoxy-β-D-tagatofuranoside (the 1-acetate of (3)) have been prepared as fructose derivatives by treatment of methyl 3,4-anhydro-β-D-tagatofuranoside (1) with (p-dimethylaminophenyl ) diphenylphosphine/diisopropyl azodicarboxylate/thioacetic S-acid and (p- dimethylaminophenyl ) diphenylphosphine/tetrachloromethane respectively. The reactions proceed in good yield, under mild conditions, and are selective for the 6-hydroxy group. The oxiran ring is unaffected under these conditions.