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 a Pd(OAc)/PPh based protocol. In contrast, maleimide-fused pyrrolo and indolo[1,2-]quinolines were obtained in a complementary methodology using CuI/L-proline.