CeCl₃·7H₂O Catalyzed C–C and C–N Bond-Forming Cascade Cyclization with Subsequent Side-Chain Functionalization and Rearrangement: A Domino Approach to Pentasubstituted Pyrrole Analogues

CeCl₃·7H₂O is found as an efficient catalyst for new intermolecular domino reactions of three-, four- and seven-component assemblies of common precursors under benign reaction conditions. Generation of enaminioesters from β-keto esters and primary amines, activation of their allylic sp³ C–H, vinylic sp² C–H and N–H bonds, multi C–C and C–N bond-forming cascade cyclization with 1,2-diketones and subsequent side-chain alkylation have been developed to construct functionalized pentasubstituted pyrroles and their chiral analogues. The scope of the domino reaction is successfully explored toward synthesis of highly aryl-substituted pyrroles, pentasubstituted pyrroles bearing C2-olefinic side-chain and spiro-2-pyrrolinones and their chiral analogues via unusual side-chain amination, elimination and ring contraction. The new domino reaction is operationally simple, robust, substrate specific, selective and high yielding.