Primary Aminothiourea-Catalyzed Enantioselective Synthesis of Rauhut-Currier Adducts of 3-Arylcyclohexenone with a Tethered Enone on the Aryl Moiety at the Ortho-Position

An enantioselective synthesis of Rauhut-Currier (RC) adducts from 3-aryl cyclohexenone with a tethered enone moiety at the ortho-position on the aryl group is accomplished. This method provides a wide range of valuable synthetic building blocks having a unique [6-5-6] all-carbon-fused tricyclic skeleton. A primary amine-containing thiourea, a bifunctional organocatalyst, was found to be an efficient catalyst for this transformation. The piimary amine counterpart of the catalyst possibly activates the aliphatic enone via dienamine formation (HOMO activation), whereas the thiourea counterpart activates the tethered enone (LUMO activation). Considering the difficulty in achieving an RC reaction of beta,beta-disubstituted (alkyl and aryl) enones, this method would be significantly rewarding.