Ethoxycarbonylation of α-Cyano-o-toluonitrile and Cyclization to Isoquinolines and Pyrimido[4,5-c]isoquinolines

Abstract

α -Cyano-o-toluonitrile is a-ethoxycarbonylated with ethyl chloroformate and 4-dimethylamino- pyridine, and cyclized to ethyl 3-amino-1-bromoisoquinoline-4-carboxylate. This is further functionalized, and examples of third-ring annulation to pyrimido [4,5-c] isoquinolines are reported.