Azabenzocycloheptenones. Part XV. Synthesis of benzazatropones and a quinoline aldehyde by the dehydrogenation of certain tetrahydro-1-benzazepine derivatives

Abstract

4,4,7,9-Tetrabromo-1,2,3,4-tetrahydro-1-benzazepin-5-one (IV) reacts with lithium chloride in dimethylformamide to give 6,8-dibromoquinoline-4-carbaldehyde (VII) and with active manganese dioxide to give 4,7,9-tribromo-1-benzazepin-5-one (I; R¹= R⁴= H, R²= R³= R⁵= Br) and 4,7,9-tribromo-1-benzazepine-2,5-dione (VI; R¹= Br, R²= H). The latter has been converted into 4,7,9-tribromo-2-chloro-1-benzazepin-5-one (I; R¹= Cl, R⁴= H, R²= R³= R⁵= Br). 1,2,3,4-Tetrahydro-2-methyl-1-p-tolylsulphonyl-1-benzazepin-5-one (XIII; R = tosyl), the N-acetyl derivative (XIII; R = Ac) and several related compounds are reported. Treatment of ethyl γ-[N-(o-methoxycarbonylphenyl)acetamido]butyrate (XVI; R¹= Ac, R²= H) with potassium t-butoxide gave ethyl γ-(1,2-dihydro-4-hydroxy-2-oxoquinolin-1-yl)butyrate (XVII).