Rauhut-Currier reaction

The Rauhut-Currier reaction is an organic reaction describing the dimerization or isomerization of enones by action of an organophosphine of the type R₃P. ["Preparation of dialkyl-2-methylene glutamates" Rauhut, M. M.; Currier, H. U.S. Patent 3074999 1963 January 22, American Cyanamid Co., 1963. [http://patimg2.uspto.gov/.piw?Docid=03074999&homeurl=http%3A%2F%2Fpatft.uspto.gov%2Fnetacgi%2Fnph-Parser%3FSect1%3DPTO2%2526Sect2%3DHITOFF%2526p%3D1%2526u%3D%25252Fnetahtml%25252FPTO%25252Fsearch-bool.html%2526r%3D1%2526f%3DG%2526l%3D50%2526co1%3DAND%2526d%3DPALL%2526s1%3D3074999.PN.%2526OS%3DPN%2F3074999%2526RS%3DPN%2F3074999&PageNum=&Rtype=&SectionNum=&idkey=NONE&Input=View+first+page Link] ] The reaction mechanism is essentially that of the related and better known Baylis-Hillman reaction (DABCO not phosphine, carbonyl not enone) but the Rauhut-Currier reaction actually predates it by several years.

The original 1963 reaction described the dimerization of the ethyl ester of acrylic acid to the corresponding diester of 2-methylene-glutaric acid with tributylphosphine in acetonitrile:

The reaction type has been utilized in an intramolecular isomerization of di-enones to form cyclopentenes: ["Organocatalytic Michael Cycloisomerization of Bis(enones): The Intramolecular Rauhut-Currier Reaction" Long-Cheng Wang, Ana Liza Luis, Kyriacos Agapiou, Hye-Young Jang, and Michael J. Krische
J. Am. Chem. Soc.; 2002; 124(11) pp 2402 - 2403; (Communication) DOI|10.1021/ja0121686]

A similar reaction by asymmetric synthesis organocatalyzed by a protected cysteine and potassium tert-butoxide afforded a cyclohexene with 95% enantiomeric excess: ["Enantioselective Rauhut-Currier Reactions Promoted by Protected Cysteine" Carrie E. Aroyan and Scott J. Miller J. Am. Chem. Soc.; 2007; 129(2) pp 256 - 257; (Communication) DOI|10.1021/ja067139f]

In this reaction the phosphine is replaced by the thiol group of cysteine but the reaction is the same.

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