Short Regioselective Chemoenzymatic Synthesis and Biological Evaluation of 2-O-b-d-Sulfoquinovosylmonoacylglycerols

A convenient chemoenzymatic synthesis of a new class of non-natural sulfo-glycolipids – 2-O-(β-D-sulfoquinovosyl)-monoacylglycerols (2-O-β-D-SQMG) – derived from 2-O-(β-D-glucopyranosyl)glycerol and carrying acyl chains of various lengths at the 1-position of the sn-glycerol moiety, was performed with the aid of a key step involving regioselective lipase-catalyzed acylation of 2-O-(6-deoxy-6-tosyl-β-D-glucopyranosyl)-sn-glycerol (4) at its 1-position, reported here for the first time. Elaboration of the sugar moiety through thioacetate substitution of the selectively inserted tosyl group with subsequent Oxone® oxidation in the presence of unprotected primary and secondary hydroxy groups efficiently afforded the target compounds, the hexanoyl, dodecanoyl,and octadecanoyl derivatives 1a–c, which were active when tested in the EBV-EA in vitro assay for antitumor promoters.