Synthesis of 5 <i>H</i> -Pyrrolo[3,4- <i>b</i> ]Pyridin-5-Ones <i>via</i> a Cerium Chloride Catalyzed Multicomponent Cascade Process: A One-Pot Approach Incorporating Ugi-Zhu 3CR, Aza Diels–Alder, <i>N</i> -Acylation, and Aromatization Reactions

We have synthesized <i>α</i>-isocyano-<i>β</i>-phenylpropionamides 5 (a–c) using a two-step process and then created a new series of poly-substituted 5<i>H</i>-pyrrolo[3,4-<i>b</i>]pyridin-5-ones 12 (a–o) <i>via</i> a multi-component reaction. Most of the reported literature used scandium triflate and either benzene or toluene as solvents, which are not good for the environment. We have identified cerium(III) chloride as the catalyst and acetonitrile as the solvent for conversion, which is harmless to the environment. The synthetic strategy involved Ugi-Zhu 3CR (UZ-3CR), Aza Diels–Alder, <i>N</i>-acylation, and aromatization steps, yielding products in the range of 65–85%.