New efficient electrochemical synthesis of 1,5-dithioxylopyranosides in the presence of a sacrificial anode Original Research Article

Electroreduction of the disulfide derivative RSSR (5, R=C6H4COC6H4CN) on a mercury pool or a carbon gauze electrode in the presence of 2,3,4-tri-O-acetyl-5-thio-d-xylopyranosyl bromide (1), using a sacrificial zinc anode gave an α,β anomeric mixture of [4-(4-cyanobenzoylphenyl)] 2,3,4-tri-O-acetyl-1,5-dithio-d-xylopyranoside (6) in 40–70% yield, according to the experimental conditions used (nature of solvent, electrolyte salt, and temperature). High selectivity favouring the α anomer of 6 is observed starting from the α anomer of 1. Mechanistic aspects are discussed.