Synthesis of a human urate transporter-1 inhibitor, an arginine vasopressin antagonist, and a 17β-hydroxysteroid dehydrogenase type-3 inhibitor, using ring-expansion of cyclic ketoximes with DIBALH

Synthesis of three clinical candidates for medicines, a human urate transporter-1 inhibitor, an arginine vasopressin antagonist, and a 17β-hydroxysteroid dehydrogenase type-3 inhibitor, is described. These compounds were synthesized via construction of their 3,4-dihydro-2H-benzo[b][1, 4]oxazine, dibenzodiazepine, and dibenzazocine skeletons, respectively, using the reductive ring-expansion reaction of the corresponding bicyclic or tricyclic oximes with diisobutylaluminum hydride.