Conivaptan hydrochloride. Treatment of heart failure, Treatment of hyponatremia, Vasopressin V-1a/V-2 antagonist.

Conivaptan hydrochloride can be obtained by two related ways: 1) Acylation of 2,3,4,5-tetrahydro-1H-1-benzazepin-5-one (I) with 4-nitrobe nzoyl chloride (II) by means of TEA in dichloromethane gives 1-(4-nitrobenz oyl)-2,3,4,5-tetrahydro-1H- 1-benzazepin-5-one (III), which is hydrogenated with H-2 over Raney Nickel in methanol, yielding the corresponding amine d erivative (IV) (1). Acylation of (IV) with biphenyl-2-carboxylic acid (V) b y means of oxalyl chloride in dichloromethane affords the expected amide (V I) (1, 2) which is brominated with either Br-2 (2) or CuBr2 (1, 2), providi ng the alpha -bromo ketone (VII). This ketone (VII) is cyclized with acetam idine hydrochloride (VIII) by means of K2CO3 in acetonitrile, furnishing a mixture of conivaptan and a oxazolo[4,5-d][1]benzodiazepine compound. Final ly, conivaptan is separated by column chromatography over silica gel and tr eated with 4N HCl to provide the desired hydrochloride (1, 2). Scheme 1. 2) The bromination of 1 -(p-toluenesulfonyl)-2,3,4,5-tetrahydro-1H-1-benzaz epin-5-one (IX) with Br-2 in CHCl3 gives the alpha -bromo ketone (X), which is cyclized with acetamidine hydrochloride (VIII) by means of K2CO3, yield ing the expected imidazobenzazepine (XI). This compound is detosylated with hot H2SO4 to provide 2-methyl-1,4,5,6-tetrahydroimidazo[4,5-d][1]benzazepi ne (XII). Acylation of (XII) with 4-nitrobenzoic acid (XIII) by means of py ridine in either hot acetonitrile or DMF affords the 6-[4-nitrobenzoyl] der ivative (XIV), which is reduced with H-2 and Raney Nickel in methanol to th e corresponding 6-(4-aminobenzoyl) compound (XV). Finally, this compound is condensed with biphenyi-2-carbonyl chloride (XVI) - obtained by treatment of biphenyl-2-carboxylic acid (V) with oxalyl chloride in CH2Cl2/DMF - by m eans of pyridine in acetonitrile and treated with 4N HCl (3). Scheme 2. Alternatively, treatment of biphenyl-2-carboxylic acid (V) with SOCl2 and D MF in CH2Cl2 provides the acyl chloride (XVI), which is condensed with 4-am inobenzoic acid (XVII) by means of N,N-dimethylaniline in acetone to give t he corresponding 4-(2-phenylbenzamido)benzoic acid (XVIII). Treatment of (X VIII) with SOCl2 and DMF in dry THF affords the acyl chloride (XIX), which is finally condensed with the inmidazobenzazepine (XII) by means of pyridin e in acetonitrile and treated with 4N HCl (3). Scheme 3.