By acylation of 5-(dimethylamino)-2,3,4,5-tetrahydro-1H-benzazepine (I) with 4-(2-methylbenzamido)benzoyl chloride (II) in the presence of potassium carbonate in acetone - H2O.
A new synthesis of OPC-31260 has been published: The reductocondensation of 1-tosyl-2,3,4,5-tetrahydro-1-benzazepin-5-one (I) with methylamine and NaBH4 gives N-(1-tosyl-2,3,4,5-tetrahydro-1-benzazepin-5-yl)-N-methylamine (II), which is methylated with formaldehyde and sodium cyanoborohydride to yield N-(1-tosyl-2,3,4,5-tetrahydro-1-benzazepin-5-yl)-N,N-dimethylamine (III). The hydrolysis of (III) with polyphosphoric acid affords N-(2,3,4,5-tetrahydro-1-benzazepin-5-yl)-N,N-dimethylamine (IV), which is acylated with 4-nitrobenzoyl chloride to the expected benzoyl derivative (VI). The reduction of the nitro group of (VI) with H2 over Pd/C affords the corresponding 4-aminobenzoyl derivative (VII), which is finally acylated with 2-methylbenzoyl chloride by means of triethylamine in dichloromethane.