DFT studies on mechanistic origins of ligand-controlled selectivity in Pd-catalyzed non-decarbonylative and decarbonylative reductive conversion of acyl fluoride.

ABSTRACT

The mechanisms and origins for ligand-controlled non-decarbonylative and decarbonylative conversions of acyl fluorides catalyzed by palladium catalysts with different ligands tricyclohexylphosphine (PCy3) and 1,2-bis(dicyclohexylphosphino)ethane (DCPE) have been investigated by density functional theory (DFT) calculations. In the case of the DCPE ligand, the favorable catalytic cycle contains four steps, oxidative addition, decarbonylation, transmetallation and reductive elimination. In the case of the PCy3 ligand, the favorable catalytic cycle proceeds by three steps, oxidative addition, transmetallation and reductive elimination. Distortion/interaction analysis indicated that decarbonylation does not occur for PCy3 owing to the repulsive interaction between PCy3 and substrates. Present calculations agree with the experimental observations and understanding these surprising ligand-controlled non-decarbonylative and decarbonylative selectivity reactions could provide important insights into the development of selective catalyst systems.