The Michael reaction or Michael addition is the nucleophilic
addition of a carbanion or another nucleophile to an
α,β-unsaturated carbonyl compound. It belongs to the larger
class of conjugate additions. This is one of the most useful
methods for the mild formation of C-C bonds. Many asymmetric
variants exist. In this scheme the R and R' substituents on the
nucleophile (a Michael donor) are electron-withdrawing groups
such as acyl and cyano making the methylene hydrogen acidic
forming the carbanion on reaction with base B:. The substituent
on the activated alkene, also called a Michael acceptor, is
usually a ketone making it an enone, but it can also be a nitro
group. As originally defined by Arthur Michael, the reaction is
the addition of an enolate of a ketone or aldehyde to an
α,β-unsaturated carbonyl compound at the β carbon. A newer
definition, proposed by Kohler, is the 1,4-addition of a doubly
stabilized carbon nucleophile to an α,β-unsaturated carbonyl
compound. Some examples of nucleophiles include b