In organic chemistry, the Michael reaction or Michael addition describes a reaction between any Michael donor (α,α disubstituted carbonyls, nitrile, sulfone, etc., — electron-withdrawing groups) and any Michael acceptor (α,β-unsaturated carbonyls, nitrile, nitro, etc., — electron-withdrawing groups). It belongs to the larger class of conjugate additions and is widely used for the mild formation of C–C bonds. Many asymmetric variants exist and depending on the conditions, Michael Additions can be diastereoselective and/or enantioselective.
In this scheme, R and R' on the nucleophile (the Michael donor) represent electron-withdrawing substituents such as acyl and cyano groups, which make the adjacent methylene hydrogen acidic enough to form a carbanion when reacted with the base, B:. For the alkene (the Michael acceptor), the R" substituent is usually a ketone, which makes the compound an enone, but it can also be a nitro group or a sulfonyl methyl fluoride. The product is called a Michael adduct.