Design and Enantioselective Synthesis of Cashmeran Odorants by Using "Enol Catalysis"1. Issue 6 (8th January 2015) - Felker, Irene
Abstract: Novel Cashmeran odorants were designed by molecular modeling. Their short syntheses involve a novel asymmetric Brønsted acid catalyzed Michael addition of unactivated α‐substituted ketones. This key transformation was realized by utilizing a new type of enol activation catalysis and affords different cyclic ketones bearing α‐quaternary stereocenters in good to excellent yields and with high enantioselectivity. Subsequent McMurry coupling and Saegusa–Ito oxidation furnished the enantiopure target odorants, one enantiomer of which indeed possesses the typical olfactory aspects of Cashmeran. Abstract : Cashmere Wood is the term perfumers use for the typical odor of Cashmeran. Novel representatives of this family were designed and stereoselectively synthesized through enol activation. The key transformation is a chiral phosphoric acid catalyzed Michael addition of enones to α‐substituted ketones to afford all‐carbon quaternary stereocenters. Olfactory analysis of the target odorants granted insight into the structural requirements for Cashmeran odorants.