Expedient Synthesis of Dihydroisoquinolines by Cascade Annulation of Nitrovinylbenzoquinone

Abstract

Abstract1,2‐Dihydroisoquinolines are important building blocks of many natural products and phamarceuticals. In continuation of our ongoing research on transformations of quinone derivatives, herein we present a catalyst‐free cascade annulation of β‐enamino esters with 2‐(2‐nitrovinyl)‐1,4‐benzoquinone, which allowed for the synthesis of various novel 1,2‐dihydroisoquinoline derivatives in moderate to good yields (60 %–99 %). This method is applicable to a wide variety of β‐enamino esters. The structure of one product was determined by an x‐ray crystal analysis. Moreover, a plausible mechanism was proposed.