A theoretical study on the palladium-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes to construct seven-membered carbocycles assisted by olefins.

Abstract

The reaction mechanisms of the Pd(ii)-catalyzed oxidative carbocyclization-alkoxycarbonylation of bisallenes to construct seven-membered carbocycles have been theoretically investigated with the aid of density functional theory (DFT) calculations. Our calculation results account for the experimental fact that the product should be the seven-membered carbocycle P1 instead of the spiro-type product P2. Our calculations indicate that CO coordination should occur prior to the ring closing step, which determines the regioselectivity. Through investigating the corresponding natural bond orbital (NBO) charges, we find that an electron withdrawing carbonyl group would decrease the electron density and lower the activation barrier. Therefore, the regioselectivity is dominated by the electronic effect.