Rauhut–Currier reaction

The Rauhut–Currier reaction, also called the vinylogous Morita–Baylis–Hillman reaction,[1] is an organic reaction describing (in its original scope) the dimerization or isomerization of electron-deficient alkenes such as enones by action of an organophosphine of the type R3P.

[2] In a more general description the RC reaction is any coupling of one active alkene / latent enolate to a second Michael acceptor, creating a new C–C bond between the alpha-position of one activated alkene and the beta-position of a second alkene under the influence of a nucleophilic catalyst.

The original 1963 reaction described the dimerization of the ethyl acrylate to the ethyl diester of 2-methylene-glutaric acid with tributylphosphine in acetonitrile: This reaction was also found to work for acrylonitrile.

RC cross-couplings are known but suffer from lack of selectivity.

The reactivity is improved in intramolecular RC reactions, for example in the isomerization of di-enones to form cyclopentenes:[4] A similar reaction by asymmetric synthesis organocatalyzed by a protected cysteine and potassium tert-butoxide afforded a cyclohexene with 95% enantiomeric excess:[5] In this reaction the phosphine is replaced by the thiol group of cysteine but the reaction is the same.