Lipase Regioselective O-Acetylations of a myo-Inositol Derivative: Efficient Desymmetrization of 1,3-Di-O-benzyl-myo-inositol

Abstract

Chiral myo-inositol derivatives play key roles in cell-signaling processes. Despite the relevance of these compounds, few syntheses of them rely on enantioselective catalytic reactions. Even fewer reports describe the use of desymmetrization of myo-inositol derivatives. In fact, most routes involve resolution by derivatization. Thus, a symmetrical partially protected myo-inositol derivative, 1,3-di-O-benzyl-myo-inositol (1), was used as a substrate in fast lipase-catalyzed desymmetrization reactions. Among the lipases tested, both Lipozyme RM-IM and Lipozyme TL-IM were effective in catalyzing the formation of the chiral acetate l-(+)-6-O-acetyl-1,3-di-O-benzyl-myo-inositol [l-(+)-2] with high conversion (98–99 %) and ee (>99 %). Conversely, Novozyme 435 and Lipomod 34P as biocatalysts showed different regioselectivity, leading to the formation of the symmetrical 5-O-acetylated product. We were able to reuse TL-IM lipase seven times without any noticeable decrease in the conversion. Acetate l-(+)-2 is a potential precursor of biologically active myo-inositol derivatives and other relevant materials for cell biology studies.