Synthesis of annulated dihydroisoquinoline heterocycles via their nitrogen ylides

3,4-Dihydro-6,7-dimethoxyisoquinoline-1-acetonitrile reacts with some α-bromoketones in dry benzene to give the corresponding isoquinolinium salts, which undergo intramolecular cyclization to give pyrrolo[2,1-a]isoquinolines. Cross-coupling of the latter compounds with some aryldiazonium chlorides resulted in the formation of 3-arylhydrazonopyrrolo[2,1-a]isoquinolines, 3-arylazopyrrolo[2,1-a]isoquinolines and 3-aryl-1,2,3-triazolo[5,1-a]isoquinolines, respectively. The structures of the products were established on the basis of their elemental and spectral analyses as well as X-ray single crystal studies.

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