Concise synthesis of pyrrolo[3,4-c]quinolines via a P(NMe2)3-catalyzed [4 + 2] annulation followed by a Zn/AcOH-mediated reduction–hydroamination–isomerization

Abstract

A P(NMe₂)₃-catalyzed [4 + 2] annulation of 2-amino-β-nitrostyrenes and β′-acetoxy allenoates followed by a Zn/AcOH-mediated reduction–hydroamination–isomerization has been developed. A range of tetrahydroquinolines and pyrrolo[3,4-c]quinolines bearing an all-carbon quaternary stereogenic center were smoothly synthesized in moderate yields. The protocol is a practical and scalable strategy, and establishes a core structural moiety of natural products and bioactive molecules.