Fused s ‐triazino heterocycles. XVI . 13 H ‐1,3,7,8,12a, 13c‐hexaazabenzo[ de ]naphthacene and 1,3,7,8,11b, 12,14,14d‐octaazadibenzo[ de,hi ]naphthacene, two new ring systems

The reaction of 7,9‐dibromo‐5‐tribromomethyl‐2‐ t ‐butyl‐4‐cyano‐1,3,6,9b‐tetraazaphenalene ( 1a ) with 2‐amino‐5‐picoline is shown to give 4,6‐dibromo‐2‐ t ‐butyl‐13‐imino‐11‐methyl‐13 H ‐1,3,7,8,12a,13c‐hexaazabenzo[ de ]naphthacene ( 3 ) and the isomeric 7,9‐dibromo‐2‐ t ‐butyl‐4‐cyano‐5 N ‐(5‐methyl‐2‐pyridyl)amino‐1,3,‐6,9b‐tetraazaphenalene ( 2a ). A related annulation reaction of 7,9‐dibromo‐2‐ t ‐butyl‐5‐chloro‐4‐cyano‐1,3,6,9b‐tetraazaphenalene ( 1g ) with 2‐amino‐6‐trimethylacetamidopyridine leads in two steps to 4,6‐dibromo‐2,13‐di‐ t ‐butyl‐1,3,7,8,11b,12,14,14d‐octaazadibenzo[ de,hi ]naphthacene ( 4a ). The preparation of 1g , 5‐azido‐7,9‐dibromo‐2‐ t ‐butyl‐4‐cyano‐1,3,6,9b‐tetraazaphenalene ( 1c ) and the reaction of the latter with pyrrolidine leading to 7,9‐dibromo‐2‐ t ‐butyl‐4‐cyano‐5‐(1‐pyrrolidino)‐1,3,6,9b‐tetraazaphenalene ( 1e ) are also reported. Attempted displacement of the azido‐group on 1c by 2,6‐diaminopyridine affords surprisingly 5‐amino‐7,9‐dibromo‐2‐ t ‐butyl‐4‐cyano‐1,3,6,9b‐tetraazaphenalene ( 1d ).