Syntheses of Imidazo‑, Oxa‑, and Thiazepine Ring Systems via Ring-Opening of Aziridines/Cu-Catalyzed C–N/C–C Bond Formation

A simple and unpredicted synthetic pathway toward racemic and scalemic tetrahydrodibenzoimidazoazepines has been invented serendipitously proceeding through an SN2-type ring-opening of N-activated aziridines with 2-bromobenzylamine followed by a hitherto unprecedented cascade cyclization reaction sequence comprising a Cu-catalyzed cross dehydrogenation C–N coupling and an Ullmann C–C bond formation reaction. The tetrahydrobenzoxazepine and the tetrahydrobenzothiazepine derivatives have also been synthesized via the ring-opening of aziridines with 2-bromobenzyl alcohols and -mercaptan, respectively, followed by Cu-catalyzed N-arylation reaction.