A chemoenzymatic asymmetric synthesis of the hydroxy acid segment of schulzeines B and C

A chemoenzymatic asymmetric synthesis of the title compound was developed by a building-block approach. The key steps of the synthesis were (i) an enantioselective lipase-catalyzed acylation of a secondary alcohol, (ii) an efficient diastereoselective addition of an alkyl-lithium reagent to a glyceraldehyde derivative, (iii) conversion of an epoxide to a one-carbon homologated allylic alcohol via a sulphorane addition, and (iv) a cross metathesis between two chiral allylic alcohols and subsequent functionalization to obtain the ethyl ester of the hydroxy acid unit of the schulzeines.