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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 ofvarious 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. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) |
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