Synthesis of polyheterocyclic pyrrolo[3,4-b]pyridin-5-ones via a one-pot (Ugi-3CR/aza diels-alder/N-acylation/aromatization/S_N2) process. A suitable alternative towards novel Aza-analogues of falipamil

We describe the one-pot synthesis of twenty polyheterocyclic pyrrolo[3,4-b]pyridin-5-ones via a cascade process (Ugi-3CR/aza Diels-Alder/N-acylation/aromatization) in 20 to 95% overall yields, as well as four pharmacologically promising analogues via an improved cascade process (Ugi-3CR/aza Diels-Alder/N-acylation/aromatization/S_N2): two piperazine-linked pyrrolo[3,4b]pyridin-5-ones in 33 and 34%, and a couple of Falipamil aza-analogues in 30 and 35% overall yields. It is worth highlighting the good substrate scope found, because final products are furnished with alkyl, aryl, and heterocyclic substituents. The use of chain-ring tautomerizable isocyanides (as key reagents for the Ugi-type three component reaction) allowed for a rapid and efficient assembly of the polysubstituted oxindoles, which were used in situ toward the complex products, conferring features like robustness, sustainability, and the one-pot approach to this synthetic methodology.