Bridged-ring nitrogen compounds. Part 7. Synthesis of the 1,4-ethano-3-benzazepine ring system

Abstract

9-Bromobenzosuberone was converted via 9-cyanobenzosuberone into several other 9-substituted benzosuberones, but attempts to cause them to cyclise to the tricyclic 1,4-ethano-3-benzazepine ring system were unsuccessful. Both ethyl phenylacetate and ethyl 3-methoxyphenylacetate were converted by conventional procedures into the corresponding 6,7,8,9-tetrahydro-5-methyl-9,10-dioxo-5,8-methano-5H-benzocycloheptenes. The 3-methoxy derivative was further converted into N-benzyl-8-bromo-6,7,8,9-tetrahydro-3-methoxy-5-methyl-9-oxo-5H-benzocycloheptene-5-carboxamide which could be converted into the tricyclic 3-benzyl-2,3,4,5-tetrahydro-8-methoxy-1-methyl-2,5-dioxo-1,4-ethano-1H-3-benzazepine and thence in two steps into both 3-benzyl-2,3,4,5-tetrahydro-8-methoxy-1-methyl-1,4-ethano-1H-3-benzazepine and 3-benzyl-2,3,4,5-tetrahydro-8-hydroxy-1-methyl-1,4-ethano-1H-3-benzazepine. Also prepared were 3-benzyl-2,3,4,5-tetrahydro-5-hydroxy-8-methoxy-1-methyl-1,4-ethano-1H-3-benzazepine and 3-benzyl-3,4-dihydro-8-methoxy-1-methyl-1,4-ethano-1H-3-benzazepin-5(2H)-one.