Synthesis of the dibenzo[ b , d ]azepine skeleton via a catalyst-free ring expansion domino reaction

In this article, a hitherto unreported catalyst-free ring expansion reaction of tetrahydroisoquinolines with o -alkynylarylaldehydes for the construction of the dibenzo[ b , d ]azepine skeleton is described. Using air as a “green” oxidant, some important biologically active dibenzo[ b , d ]azepines were produced with favorable functional group tolerance and a wide substrate scope. The synthetic potential was further confirmed by facile scale-up reactions and the synthesis of isoindoline derivatives.