A concise, efficient and versatile synthesis of amino‐substituted benzo[ b b ]pyrimido[5,4‐ f f ]azepines: synthesis and spectroscopic characterization, together with the molecular and supramolecular structures of three products and one intermediate

摘要

A concise, efficient and versatile synthesis of amino‐substituted benzo[ b ]pyrimido[5,4‐ f ]azepines is described: starting from a 5‐allyl‐4,6‐dichloropyrimidine, the synthesis involves base‐catalysed aminolysis followed by intramolecular Friedel–Crafts cyclization. Four new amino‐substituted benzo[ b ]pyrimido[5,4‐ f ]azepines are reported, and all the products and reaction intermediates have been fully characterized by IR, 1 H and 13 C NMR spectroscopy and mass spectrometry, and the molecular and supramolecular structures of three products and one intermediate have been determined. In each of N ,2,6,11‐tetramethyl‐ N ‐phenyl‐6,11‐dihydro‐5 H ‐benzo[ b ]pyrimido[5,4‐ f ]azepin‐4‐amine, C 22 H 24 N 5 , (III), 4‐(1 H ‐benzo[ d ]imidazol‐1‐yl)‐6,11‐dimethyl‐6,11‐dihydro‐5 H ‐benzo[ b ]pyrimido[5,4‐ f ]azepine, which crystallizes as a 0.374‐hydrate, C 21 H 19 N 5 ·0.374H 2 O, (VIII a ), and 6,7,9,11‐tetramethyl‐4‐(5‐methyl‐1 H ‐benzo[ d ]imidazol‐1‐yl)‐6,11‐dihydro‐5 H ‐benzo[ b ]pyrimido[5,4‐ f ]azepine, C 24 H 25 N 5 , (VIII c ), the azepine ring adopts a boat conformation, but with a different configuration at the stereogenic centre in (VIII c ), as compared with (III) and (VIII a ). In the intermediate 5‐allyl‐6‐(1 H ‐benzo[ d ]imidazol‐1‐yl)‐ N ‐methyl‐ N ‐(4‐methylphenyl)pyrimidin‐4‐amine, C 22 N 21 N 5 , (VII b ), the immediate precursor of 4‐(1 H ‐benzo[ d ]imidazol‐1‐yl)‐6,8,11‐trimethyl‐6,11‐dihydro‐5 H ‐benzo[ b ]pyrimido[5,4‐ f ]azepine, (VIII b ), the allyl group is disordered over two sets of atomic sites having occupancies of 0.688?(5) and 0.312?(5). The molecules of (III) are linked into chains by a C—H…π(pyrimidine) hydrogen bond, and those of (VII b ) are linked into complex sheets by three hydrogen bonds, one of the C—H…N type and two of C—H…π(arene) type. The molecules of the organic component in (VIII a ) are linked into a chain of rings by two C—H…π(arene) hydrogen bonds, and these chains are linked into sheets by the water components; a single weak C—H…N hydrogen bond links molecules of (VIII c ) into centrosymmetric R 2 2 (10) dimers. Comparisons are made with some related compounds.