Synthesis of fused pyrrolo[3,4-d]tetrahydropyrimidine derivatives by proline-catalyzed multicomponent reaction

Novel proline-catalyzed multicomponent reactions (MCRs) for the synthesis of fused pyrrolo[3,4-d]tetrahydropyrimidines 7 and 9 with different substituted patterns have been developed, which provide rapid access to a library of compounds 7 and 9 in medium to excellent yields, by using N-methyl-α-aryl(alkyl)aminomaleimides, amines, and aldehydes as reactants. The catalyst and the ratio of reactants were found to have significant impact on these reactions, and a reasonable mechanism was also proposed.