Chiral Guanidinium-Catalyzed Enantioselective Claisen Rearrangement

Abstract

Jacobsen and co-workers disclose the enantioselective Claisen rearrangement of O-allyl β-keto esters catalyzed by chiral guanidinium salt 1. The desired products were obtained with good yields and enantioselectivities from a broad variety of different substrates, including substituted O-allyl β-keto esters leading to the ­formation of vicinal stereocenters. The utility of the products was demonstrated in the enantio­selective construction of the hyperforin core structure. Furthermore, the recyclability of the catalyst was demonstrated, and computational studies modeling the reaction pathway and a plausible transition state are provided.