Asymmetric Modular Synthesis of Highly Functionalized Medium-Sized Carbocycles and Lactones via Ring-Closing Metathesis of Sulfoximine-Substituted Trienes

Abstract

A modular asymmetric synthesis of medium-sized carbocycles and lactones has been developed that affords highly substituted 7-, 9-, and 11-membered rings. The key steps are (1) the highly diastereoselective synthesis of sulfoximine-substituted homoallylic alcohols from allylic sulfoximines and unsaturated as well as saturated aldehydes, (2) an E-stereoselective alkylation and hydroxyalkylation of sulfoximine-substituted alkenyllithium derivatives, (3) the esterification of sulfoximine-substituted homoallylic alcohols, and (4) the ring-closing metathesis reaction of sulfoximine-substituted trienes with the ruthenium catalyst 8. Two examples for the further synthetic elaboration of the sulfoximine-substituted carbocycles are provided. The selective cleavage of the tert-butyldimethylsilyl group of 12 in the presence of the triethylsilyl group afforded the allylic alcohol 18 which was oxidized to enone 19. A cross-coupling reaction of the sulfoximine-substituted carbocycle 9 with LiCuMe2 furnished the methyl-substituted derivative 20.