N-Heterocyclic Carbene-Catalyzed Reaction of Chalcones and Enals via Homoenolate: an Efficient Synthesis of 1,3,4-Trisubstituted Cyclopentenes

Nucleophilic heterocyclic carbene-catalyzed cyclopentannulation of enals and chalcones via homoenolate has been observed for the first time. Serendipitously, the reaction lead to a very efficient synthesis of 3,4-trans-disubstituted-1-aryl cyclopentenes instead of the expected cyclopentanones. The strategy works well with thienylidene tetralone also, leading to the tricyclic cyclopentene derivative.