Enantioselective Synthesis of the Metabolites of Vasopressin V2 Receptor Antagonist OPC-31260 via Lipase-Catalyzed Transesterification

The optical isomers of 5-dimethylamino-1-[4-(2-methylbenzoylamino)benzoyl]-2,3,4,5-tetrahydro-1H-1-benzazepine (OPC-31260, 1) and its metabolites (2, 3, 4, 5 and 6) were enantioselectively synthesized. The chiral acetate 8b and alcohol 7a were prepared via the resolution of the racemic alcohol (±)-7 using the lipase-mediated transesterification in vinyl acetate. The compounds 8b and 7a were converted to the hydroxy metabolites (2a and 2b), the methylamine metabolites (3a and 3b), the dimethylamines (1a and 1b), and the amine metabolites (4a and 4b) in several steps while maintaining their absolute configurations. The 4,5-diol metabolites (5a, 5b, 6a and 6b) were synthesized from the key intermediates obtained by the lipase-catalyzed transesterification.