Elucidating the Mechanism and Chemoselectivity in the PBu₃‐Catalyzed Rauhut‐Currier Reaction of Chalcone with Ethyl Acrylate

Abstract

Disclosing the chemoselectivity and regioselectivity of phosphine‐catalyzed Rauhut‐Currier (R−C) reaction remains a challenge. Here, a comprehensive study on the possible mechanisms and origins of the chemoselectivity and regioselectivity of PBu3‐catalyzed R−C reactions between ethyl acrylate and chalcone is performed by DFT. Both cross and homo R−C reactions are investigated and compared. The computational results show that the cross R−C reaction is energetically favorable than the homo R−C reaction, with head‐to‐tail product being generated preferentially. Moreover, the C−C bond formation process is identified to be the regioselectivity‐ and chemoselectivity‐determining step. The CDFT and Parr function analyses are successfully used to predict the origins of chemoselectivity and regioselectivity, respectively. This work would provide a valuable case for exploring the origins of the chemoselectivity and regioselectivity of the phosphine catalyzed reactions, which should be helpful to understand and control the selectivities by rational design.