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

A concise, efficient and versatile synthesis of amino‐substituted benzo[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]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[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]azepines are reported, and all the products and reaction intermediates have been fully characterized by IR, ¹H and ¹³C NMR spectroscopy and mass spectrometry, and the molecular and supramolecular structures of three products and one intermediate have been determined. In each of <italic>N</italic>,2,6,11‐tetramethyl‐<italic>N</italic>‐phenyl‐6,11‐dihydro‐5<italic>H</italic>‐benzo[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]azepin‐4‐amine, C₂₂H₂₄N₅, (III), 4‐(1<italic>H</italic>‐benzo[<italic>d</italic>]imidazol‐1‐yl)‐6,11‐dimethyl‐6,11‐dihydro‐5<italic>H</italic>‐benzo[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]azepine, which crystallizes as a 0.374‐hydrate, C₂₁H₁₉N₅·0.374H₂O, (VIII<italic>a</italic>), and 6,7,9,11‐tetramethyl‐4‐(5‐methyl‐1<italic>H</italic>‐benzo[<italic>d</italic>]imidazol‐1‐yl)‐6,11‐dihydro‐5<italic>H</italic>‐benzo[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]azepine, C₂₄H₂₅N₅, (VIII<italic>c</italic>), the azepine ring adopts a boat conformation, but with a different configuration at the stereogenic centre in (VIII<italic>c</italic>), as compared with (III) and (VIII<italic>a</italic>). In the intermediate 5‐allyl‐6‐(1<italic>H</italic>‐benzo[<italic>d</italic>]imidazol‐1‐yl)‐<italic>N</italic>‐methyl‐<italic>N</italic>‐(4‐methylphenyl)pyrimidin‐4‐amine, C₂₂N₂₁N₅, (VII<italic>b</italic>), the immediate precursor of 4‐(1<italic>H</italic>‐benzo[<italic>d</italic>]imidazol‐1‐yl)‐6,8,11‐trimethyl‐6,11‐dihydro‐5<italic>H</italic>‐benzo[<italic>b</italic>]pyrimido[5,4‐<italic>f</italic>]azepine, (VIII<italic>b</italic>), 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<italic>b</italic>) 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<italic>a</italic>) 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<italic>c</italic>) into centrosymmetric <italic>R</italic>₂²(10) dimers. Comparisons are made with some related compounds. [ABSTRACT FROM AUTHOR]