Metal-mediated allylation of enzymatically oxidized methyl α-d-galactopyranoside Original Research Article

The C-6 unit of methyl α-d-galactopyranoside was selectively modified by combining enzymatic oxidation with an indium-mediated allylation reaction. The Barbier–Grignard type reaction, where a carbonyl group reacts with an allyl halide, proceeds in aqueous solution, even with water as the only solvent; thus carbohydrates can be modified without the need for drying or protection–deprotection steps. The corresponding homoallyl alcohols are produced in high yields of >90% in the reactions with allyl bromide and cinnamyl chloride. The main products were isolated and characterized by GC–MS and NMR spectroscopy.