Enzymatic dissymmetrization of meso-2,3-dimethylbutane-1,4-diol and its diacetate. Synthesis of scalemic (-)-lasiol

Abstract

Acylation of meso-2,3-dimethylbutane-1,4-diol with vinyl acetate in the presence of porcine pancreatic lipase (PPL) leads to the dextrorotatory monoacetate of the above diol with enatiomeric excess (ee) 58-64%. Absolute configuration of this scalemic specimen was determined by its sequential transformation to levorotatory lasiol, a metabolite of the Lasius ants. Partial hydrolysis of the corresponding meso-diacetate, mediated by PPL or by the Pseudomonas sp. lipase affords the monoacetate of opposite configuration with ee 72-86%, a formal intermediate in the synthesis of (3S,4R)-faranal. Other microbial lipases used are distinctive in low chemoselectivity.