Nitration of 5-bromoisoquinoline (I) employing KNO3 in H2SO4 provides 5-bromo-8-nitroisoquinoline (II). Quaternization of isoquinoline (II) with dimethyl sulfate, followed by reduction of the resultant N-methyl isoquinolinium salt (III) with NaBH4 in cold HOAc furnishes the tetrahydroisoquinoline (IV). Subsequent Suzuki coupling between the bromotetrahydroisoquinoline (IV) and 4-chlorophenylboronic acid (V) yields the 5-aryl isoquinoline derivative (VI). The nitro group of (VI) is further reduced to amine (VII) by catalytic hydrogenation over Raney nickel. The key isatin compound (IX) is then obtained by condensation of amine (VII) with chloral (VIII) in the presence of hydroxylamine hydrochloride and sodium sulfate. Finally, isatin (IX) is converted to the desired oxime by treatment with hydroxylamine hydrochloride in EtOH.
1-Amino-5,6,7,8-tetrahydronaphthalene (I) is protected as the corresponding acetamide (II) by treatment with Ac2O in the presence of NaOAc. Bromination of (II) with bromine in trifluoroacetic acid leads to (III). Then, Suzuki coupling between aryl bromide (III) and 4-chlorophenylboronic acid (IV) furnishes the aryl tetrahydronaphthalene (V). Acetamide hydrolysis in (V) under alkaline conditions provides amine (VI). Condensation of (VI) with chloral and hydroxylamine, followed by cyclization in hot methanesulfonic acid generates the isatin derivative (VII). This is finally converted to the title oxime upon treatment with hydroxylamine hydrochloride in ethanol.