Enantioselective rauhut-currier reactions promoted by protected cysteine

We report highly enantioselective examples of the Rauhut-Currier cycloisomerization reaction (the vinylogous Morita-Baylis-Hillman reaction). The reaction is highly practical and is catalyzed by a commercially available derivative of the proteinogenic amino acid cysteine. Reactions are conducted in the presence of potassium tert-butoxide and a critical concentration of water in bulk acetonitrile. A mechanistic model is advanced that may account for reaction selectivity that is predicated on organizational chelation of K ion in the product-determining step in which the Cys derivative undergoes limination.