From methyl d-glucopyranoside to methyl d-allopyranoside via the Mitsunobu reaction

Methyl β-d-glucopyranoside reacted with a 4-molar excess of the Mitsunobu reagents (triphenylphosphine–diethyl azodicarboxylate–benzoic acid) under Weinges et al. [Carbohydr. Res., 164 (1987) 453–458] conditions to furnish four differently benzoylated methyl β-d-allopyranosides in a very good overall yield. The same reaction applied to methyl α-d-glucopyranoside yielded allosides in a low yield and nine other sugar products. These results give an insight into the course of the Mitsunobu esterification–inversion reaction.