2,5-Disubstituted 3,4-dihydro-2H-benzo[b][1,4]thiazepines as potent and selective V2 arginine vasopressin receptor antagonists

A number of 2,5-disubstituted benzothiazepines were synthesized and screened for their ability to inhibit arginine vasopressin binding to the human V2 and V1a receptor subtypes. The more active compounds were subsequently analyzed for their antagonist activity in in vitro functional assays. The SAR showed a preference for an acidic unit appended from the benzothiazepine scaffold. This substitution pattern afforded the most potent and selective analogues in the series. The carboxymethyl analogue 4, showed a 140-fold greater selectivity for the V2 over the V1a receptor in the binding assay. In the cell-based functional assays this analogue was a potent and selective antagonist of the V2 receptor. The in vitro SAR of the series and a description of the in vivo studies around compound 4 is described.