Cooperative Rh(II)/Pd(0) Dual Catalysis for the Synthesis of Carbo- and Heterocyclic Compounds

Dual transition-metal catalysis has been introduced as a robust tool to synthesize a diverse range of organic compounds that cannot to be accessed by traditional single-metal catalysis. In this context, we have recently developed cooperative Rh(II)/Pd(0) dual catalytic systems that have been utilized for the preparation of heterocyclic compounds through the reaction between Rh(II)-carbenoid and π-allyl Pd(II)-complex intermediates in either synergistic or tandem relay catalysis. In synergistic Rh(II)/Pd(0) dual catalysis, the two reactive intermediates are generated simultaneously, which then undergo formal [6+3] dipolar cycloaddition to afford medium-sized heterocyclic compounds. On the other hand, tandem relay dual catalysis can be enabled through judicious choice of reaction parameters, which proceed through the insertion of Rh(II)-carbenoid into O H or C H bonds, followed by Pd(0)-catalyzed allylation to provide allylated benzo-fused cyclic compounds or chiral β-lactam derivatives.