Theoretical insights into phosphine‐catalyzed [4 + 2] annulation of allenoates with thiazolone‐derived alkenes

Mechanism of [4 + 2] annulation of allenoates with thiazolone‐derived alkenes catalyzed by phosphine has been studied using DFT. Introduction of chiral phosphine catalyst can generate optically active products in good yield with excellent enantioselectivity, whereas in the use of achiral phosphine catalyst, products were not enantioselective. Several theoretical analyses indicate that the phosphine catalyst can enhance the nucleophilicity of reactant and reduce the energy difference gap of the interacting HOMO and LUMO orbitals.