Enantiomerically pure cyclopropyl hemiacetals: lipase-catalyzed synthesis of chiral, nonracemic ester homoenolate equivalents.

ABSTRACT

[figure see text] Enantiomerically pure cyclopropyl hemiacetals can be obtained by lipase-catalyzed kinetic resolution of their acylated congeners. It is demonstrated that lipases from Candida antarctica and Pseudomonas cepacia show enantiodivergent behavior toward these substrates. Subsequent ring opening of these building blocks can be achieved with ZnCl2 leading to chiral, nonracemic alpha-substituted homoenolate anions.