<i>N</i>‑Benzoyl-1,5-benzothiazepine and Its <i>S</i>‑Oxide as Vasopressin Receptor Ligands: Insight into the Active Stereochemistry around the Seven-Membered Ring

Abstract

The stereochemistry of <i>N</i>-benzoyl-1,5-benzothiazepine and its <i>S</i>-oxide derivatives as vasopressin receptor ligands was examined in detail by freezing the conformation with a methyl group at the C6 or C9 of 1,5-benzothiazepine. It was revealed that the active forms recognized by the receptors are (<i>cis</i>,a<i>S</i>) for 1,5-benzothiazepine (<b>5</b>–<b>7</b>)-<b>II</b> and (<i>cis</i>,1<i>S,</i>a<i>S</i>) (<i>syn</i>) for its <i>S</i>-oxide (<b>8</b>–<b>10</b>)-<b>II</b>. The C9-methyl derivative of 1,5-benzothiazepine <i>S</i>-oxide (<b>10</b>-<b>II</b>) was designed and synthesized, achieving the putative active <i>syn</i>-isomer