Two distinct protocols for the synthesis of unsymmetrical 3,4-disubstituted maleimides based on transition-metal catalysts.

Two tandem catalytic systems are described for the synthesis of novel 3,4-disubstituted maleimides using the same Ugi adducts as starting materials. 4-Aryl-3-pyrrolyl- and 4-aryl-3-indolyl-maleimides were successfully obtained via a Pd(OAc) 2 /PPh 3 based protocol. In contrast, maleimide-fused pyrrolo and indolo[1,2- a ]quinolines were obtained in a complementary methodology using CuI/L-proline. These strategies involved a combination of benzylic amine oxidation, trans -amidation, intramolecular Knoevenagel condensation, and N -arylation reactions. Computational investigations provide further insights into this reaction sequence.