Bridged-ring nitrogen compounds. Part 1. A synthesis of a 2,3,4,5-tetrahydro-1, 4-ethano-1-benzazepin-5(1H)-one

Abstract

2, 3, 4, 5-Tetrahydro-1, 4-dimethyl-5-oxo-1-benzazepine has been obtained by methylation (Mel) of 2, 3, 4, 5-tetrahydro-5-oxo-1H-1-benzazepine using lithium di-isopropylamide, but a similar attempted alkylation reaction with 1, 2-di-iodoethane was unsuccessful. A synthesis of N-(3-methoxyphenyl)isonipecotic acid was developed from ethyl isonipecotate and dihydroresorcinol : the acid or its O-demethylated ethyl ester was cyclised in polyphosphoric acid at 180–190 °C yielding 2, 3, 4, 5-tetrahydro-8-hydroxy-1.4-ethano-1-benzazepin-5(1H)-one. Syntheses of perhydro-1-(m-methoxyphenyl)azocin-5-one and perhydro-1-(p-tolylsulphonyl)azocin-5-one are described