Highly enantioselective isomerization of primary allylic alcohols catalyzed by (P,N)-iridium complexes

Mantilli, Luca; Gérard, David; Torche, Sonya; Besnard, Céline; Mazet, Clément

doi:10.1351/PAC-CON-09-09-10

Pure Appl. Chem., 2010, Vol. 82, No. 7, pp. 1461-1469

http://dx.doi.org/10.1351/PAC-CON-09-09-10

Published online 2010-05-04

Highly enantioselective isomerization of primary allylic alcohols catalyzed by (P,N)-iridium complexes

Luca Mantilli, David Gérard, Sonya Torche, Céline Besnard and Clément Mazet*

Department of Organic Chemistry, University of Geneva, quai Ernest Ansermet 30, CH-1211 Geneva 4, Switzerland

Abstract: The catalytic asymmetric isomerization of allylic amines to enamines stands out as one of the most accomplished and well-studied reactions in asymmetric catalysis as illustrated by its industrial application. In contrast, the related asymmetric isomerization of primary allylic alcohols to the corresponding aldehydes still constitutes a significant challenge in organic synthesis. Herein, we show that under appropriate reaction conditions, iridium-hydride catalysts promote the isomerization of primary allylic alcohols under very mild reaction conditions. The best catalysts deliver the desired chiral aldehydes with unprecedented levels of enantioselectivity and good yields. Mechanistic hypotheses have been drawn based on preliminary investigations.