Acylation of 2,3,4,5-tetrahydro-1H-1-benzazepin-5-one (I) with 4-nitrobenzoyl chloride (II) by means of TEA in CH2Cl2 gives 1-(4-nitrobenzoyl)-2,3,4,5-tetrahydro-1H-1-benzazepin-5-one (III), which is hydrogenated with H2 over Raney-Ni in MeOH, yielding the corresponding amine derivative (IV). Acylation of (IV) with biphenyl-2-carboxylic acid (V) by means of oxalyl chloride in CH2Cl2 affords the expected amide (VI) which is brominated with either Br2 or CuBr2, providing the alpha-bromo ketone (VII). This ketone (VII) is cyclized with acetamidine hydrochloride (VIII) by means of K2CO3 in MeCN, furnishing a mixture of conivaptan and oxazolo[4,5-d][1]benzodiazepine compound. Finally, conivaptan is separated by column chromatography over silica gel and is treated with 4N HCl to provide the desired hydrochloride.
The bromination of 1-(p-toluenesulfonyl)-2,3,4,5-tetrahydro-1H-1-benzazepin-5-one (IX) with Br2 in CHCl3 gives the alpha-bromo ketone (X), which is cyclized with acetamidine hydrochloride (VIII) by means of K2CO3, yielding the expected imidazo-benzazepine (XI). This compound is detosylated with hot H2SO4 to provide 2-methyl-1,4,5,6-tetrahydroimidazo[4,5-d][1]benzazepine (XII). Acylation of (XII) with 4-nitroben-zoic acid (XIII) by means of pyridine in either hot MeCN or DMF affords the 6-(4-nitro-benzoyl) derivative (XIV), which is reduced with H2 and Raney-Ni in MeOH to the corres-ponding 6-(4-aminobenzoyl) compound (XV). Finally, this compound is condensed with biphenyl-2-carbonyl chloride (XVI) [ obtained by treatment of biphenyl-2-carboxylic acid (V) with oxalyl chloride in CH2Cl2/DMF] by means of pyridine in acetonitrile and treated with 4N HCl.
Alternatively, treatment of biphenyl-2-carboxylic acid (V) with SOCl2 and DMF in CH2Cl2 provides the acyl chloride (XVI), which is condensed with 4-aminobenzoic acid (XVII) by means of N,N-dimethylaniline in acetone to give the corresponding 4-(2-phenylbenzamido)benzoic acid (XVIII). Treatment of (XVIII) with SOCl2 and DMF in dry THF affords the acyl chloride (XIX), which is finally condensed with the inmidazobenzazepine (XII) by means of pyridine in MeCN and treated with 4N HCl.