Cu(I)/TF-BiphamPhos Catalyzed Reactions of Alkylidene Bisphosphates and Alkylidene Malonates with Azomethine Ylides: Michael Addition versus 1,3-Dipolar Cycloaddition

Cu(I)/TF-BiphamPhos catalyzed reactions of alkylidene bisphosphates and alkylidene malonates with azomethine ylides have been investigated with the aid of density functional theory calculations at the B3LYP level. Michael addition and 1,3-dipolar cycloaddition were calculated. For reactions of alkylidene bisphosphates, the Michael addition pathway is both kinetically and thermodynamically more favorable than 1,3-dipolar cycloaddition. However, for reactions of alkylidene malonates, the 1,3-dipolar cycloaddition pathway is kinetically and thermodynamically more favorable than Michael addition. In the reactions of alkylidene bisphosphates, the significant repulsion between the two bulky phosphonate groups of the alkylidene bisphosphates and the phenyl substituent of the azomethine ylides suppresses 1,3-dipolar cycloaddition and favors Michael addition. In the reactions of alkylidene malonates the less bulky ester groups in the alkylidene malonates allow 1,3-dipolar cycloaddition to occur.