Michael Addition

Abstract

The Michael reaction is defined as the conjugate 1,4‐addition of carbon nucleophiles to acceptor‐substituted CC bonds. Enolates of β‐dicarbonyl compounds represent typical nucleophiles in this classical base‐catalyzed CC‐bond‐forming reaction, yielding 1,5‐dicarbonyl compounds as products. In some cases, metal catalysts as simple as FeCl 3  6 H 2 O can be applied, avoiding basic reaction conditions and thus resulting in an improved chemoselectivity compared with base catalysis. The Michael reaction can be performed in an intramolecular or vinylogous fashion, and is known as an elementary step in several reaction sequences. In most cases, Michael reaction products have at least one new stereogenic center. In order to achieve asymmetric reactions, chiral auxiliaries, chiral Brönstedt bases, or metal complexes bearing chiral ligands have been reported as catalysts for the Michael reaction.