Theoretical investigation of the CC bond activation mechanism of benzocyclobutenones and dienamides catalyzed by Rh(I): The ligand-controlled products selectivity

Abstract

The mechanisms and origins of ligand-controlled Rh(I)-catalyzed CC activation of benzocyclobutenones and their coupling with pendant dienamides were investigated using DFT. This study specifically examined the pathways and factors influencing product formation, with particular emphasis on the role of phosphine ligands. Triphenylphosphine (PPh₃) facilitates the formation of the type-II [4 + 4] product, anti-Bredt benzofused aza-bicyclo[5.3.1] bridged compound. Conversely, the bidentate diphosphate ligand 1,3-bis(diphenylphosphino)propane (dppp) introduces significant steric hindrance, which promotes the formation of alternative fused tricycle product.