Bridging between organocatalysis and biocatalysis: Asymmetric addition of acetaldehyde to β-nitrostyrenes catalyzed by a promiscuous proline-based tautomerase

Abstract

Non-natural beauty: The enzyme 4-oxalocrotonate tautomerase (4-OT) promiscuously (i.e., with non-natural activity) catalyzes the Michael-type addition of acetaldehyde to nitrostyrene. Catalysis likely proceeds via enamine formation of the amino-terminal proline residue of 4-OT with acetaldehyde (see picture), reminiscent of organocatalysis. High stereoselectivity, low catalyst loading, and water as reaction medium characterize this methodology. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.