137975-06-5

Mozavaptan is an oral vasopressin V2 antagonist that has been launched in Japan for inappropriate antidiuretic hormone secretion syndrome (IADHS), an affliction manifesting as hyponatremia. It joins another nonpeptidic benzazepine, conivaptan, which corrects sodium and water imbalance by blocking the renal V2 receptor resulting in enhanced diuresis, thereby effectively increasing serum sodium concentration. While conivaptan inhibits both V1 and V2 receptors, mozavaptan is significantly more selective for V2 (IC50 of 14nM vs. 1.2 mM for V1).

Otsuka (Japan)

vasopressin V2 receptor antagonist

ChEBI: Mozavaptan is a member of benzamides.

Physuline

The reported synthesis of mozavaptan is shown in the scheme. Readily available benzazepin-5-one 39 was refluxed with 40% methyl amine methanol solution in the presence of molecular sieves for 5h followed by the reduction of the resulting imine with sodium borohydride to give the monomethyl amine. Reductive alkylation of the monomethyl amine with formaldehyde in the presence of sodium cyanoborohydride gave the dimethyl amino benzazepine 40. Removal of the tosyl group was facilitated by heating 40 in polyphosphoric acid at 150oC for 2 h to give 41 in 97% yield. Reaction of the resulting benzazepine 41 with p-nitrobenzoyl chloride (42) in the presence of triethylamine provided amide 43 which was hydrogenated in the presence of 10% Pd/C in ethanol at room temperature to give aniline 44. Acylation of aniline 44 with 2-methylbenzoylchloride (45) in the presence of triethylamine gave mozavaptan (VI) in 54% yield.