Synthesis of 3<i>H</i>-Pyrazolo[3,4-<i>c</i>]isoquinolines and Thieno[3,2-<i>c</i>]isoquinolines via Cascade Imination/Intramolecular Decarboxylative Coupling

Abstract

A general approach for the synthesis of 3H-pyrazolo[3,4-c]isoquinolines and thieno[3,2-c]isoquinolines is described involving the implementation of a cascade imination/intramolecular decarboxylative coupling between potassium 2-amino(hetero)benzoates and 2-haloarylaldehydes. The reactions of pyrazole-based substrates require a Pd-Cu bimetallic system for superior yields whereas the thienyl-based substrates afford the products in excellent yields with a Pd-catalyst only.