Organocatalytic Asymmetric Addition of Alcohols and Thiols to Activated Electrophiles: Efficient Dynamic Kinetic Resolution and Desymmetrization Protocols

Bifunctional urea-based cinchona alkaloid derivatives have been shown to promote highly efficient DKR reactions of azalactones using an alcohol nucleophile. The optimum catalyst is remarkably insensitive to the steric bulk of the amino acid residue, allowing alanine-, methionine-, and phenylalanine-derived azalactones to undergo DKR with unprecedented levels of enantioselectivity using a synthetic catalyst. The first DKR of these substrates by thiols and the highly enantioselective desymmetrization of a meso-glutaric anhydride by thiolysis are also reported.