| Abstract: | A versatile synthetic method has been developed for the formation of variously substituted polycyclic pyrimidoazepine derivatives, formed by nucleophilic substitution reactions on the corresponding chloro‐substituted compounds; the reactions can be promoted either by conventional heating in basic solutions or by microwave heating in solvent‐free systems. Thus, (6RS)‐6,11‐dimethyl‐3,5,6,11‐tetrahydro‐4H‐benzob]pyrimido5,4‐f]azepin‐4‐one, C14H15N3O, (I), was isolated from a solution containing (6RS)‐4‐chloro‐8‐hydroxy‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzob]pyrimido5,4‐f]azepine and benzene‐1,2‐diamine; (6RS)‐4‐butoxy‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzob]pyrimido5,4‐f]azepin‐8‐ol, C18H23N3O2, (II), was formed by reaction of the corresponding 6‐chloro compound with butanol, and (RS)‐4‐dimethylamino‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzob]pyrimido5,4‐f]azepin‐8‐ol, C16H20N4O, (III), was formed by reaction of the chloro analogue with alkaline dimethylformamide. (6RS)‐N‐Benzyl‐8‐methoxy‐6,11‐dimethyl‐6,11‐dihydro‐5H‐benzob]pyrimido5,4‐f]azepin‐4‐amine, C22H24N4O, (IV), (6RS)‐N‐benzyl‐6‐methyl‐1,2,6,7‐tetrahydropyrimido5′,4′:6,7]azepino3,2,1‐hi]indol‐8‐amine, C22H22N4, (V), and (7RS)‐N‐benzyl‐7‐methyl‐2,3,7,8‐tetrahydro‐1H‐pyrimido5′,4′:6,7]azepino3,2,1‐ij]quinolin‐9‐amine, C23H24N4, (VI), were all formed by reaction of the corresponding chloro compounds with benzylamine under microwave irradiation. In each of compounds (I)–(IV) and (VI), the azepine ring adopts a conformation close to the boat form, with the C‐methyl group in a quasi‐equatorial site, whereas the corresponding ring in (V) adopts a conformation intermediate between the twist‐boat and twist‐chair forms, with the C‐methyl group in a quasi‐axial site. No two of the structures of (I)–(VI) exhibit the same range of intermolecular hydrogen bonds: different types of sheet are formed in each of (I), (II), (V) and (VI), and different types of chain in each of (III) and (IV). |
