Synthesis of Isoquinolines by Cycloaddition of Arynes to 1,2,4-Triazines

Article abstract of DOI:10.1016/S0040-4020(01)89873-2

Benzyne has been generated from benzenediazonium-2-carboxylate in the presence of several 1,2,4-triazines 1 and isoquinolines 2 have been isolated in moderate yield. 1-Aminobenzotriazole was also used as the source of benzyne and isoquinolines were again isolated in moderate yield from these reactions. 4-Methylbenzyne, which was generated from 5-methylanthranilic acid, reacted unselectively with the triazines to give mixtures of 6- and 7-methylisoquinolines 3 and 4.On the other hand reactions of 3-methylbenzyne with the triazines 1d and 1e proceeded with high regioselectivity, giving only the 5-methylisoquinoline 5a and the 8-methylisoquinoline 6b, respectively.