Preparation of chiral building blocks for the enantioselective total synthesis of ent-kauranoids by the pig liver esterase-catalyzed asymmetric hydrolysis of a dialkyl malonate-type prochiral diester

The preparation of chiral building blocks, suitable for use in the enantioselective total synthesis of kauranoids and ent-kauranoids, is reported herein. The pig liver esterase-catalyzed asymmetric hydrolysis of dimethyl 3,3-dimethyl-2-methylenecyclohexane-1,2-dicarboxylate, a malonate-type prochiral diester, afforded the corresponding half-ester in 96% yield and with 99% enantiomeric excess. The absolute configuration of the half-ester was determined by X-ray crystallographic analysis of its derivative and its enantiodivergent transformations are also described herein.