Azonia-azulene salts. Part I. Synthesis of some 9-hydroxypyrrolo-[1,2-a] azepinium salts and 10-hydroxyazepino[1,2-a]idolium salts

Abstract

The syntheses of 1,2,23-tribromopyrrolo[1,2-a]azepin-9-one (23) and 11-methylazepino[1,2-a]indol-10-one (20), by a one-step elimination reaction from 1,2,3,8,8-pentabromo-6,7,8,9-tetrahydro-5H-pyrrolo[1,2-a]azepin-9-one (22) or 9,9-dibromo-7,8,9,10-tetrahydro-11-methyl-6H-azepino[1,2-a]indol-10-one (19) respectively, are described. The Structures of the azepinones were established from their n.m.r.spectra and by hydrogenation of the pyrroloazepinone (23). Both azepinones on protonation gave hydroxyzonia-azulene salts; the pyrroloazepinone (23) with Meerwein's reagent gave 1,2,3-tribromo-9-ethoxypyrrolo[1,2-a]azepinium fluoroborate (25).