Synthesis of Tolvaptan

Tolvaptan,a selective nonpeptide arginine vasopressin V_2 receptor antagonist,was synthesized from 7-chloro-5-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine by acylation and reduction to give 1-(4-amino-2-methylbenzoyl) -7- chloro-5-oxo-2,3,4,5-tetrahydro-1H-1-benzazepine,which was subjected to acylation with 2-methylbenzoyl chloride and reduction with sodium borohydride with an overall yield of about 45%.