Stereoselective construction of azepine-containing bridged scaffolds via organocata-lytic bicyclization of yne-allenone esters with nitrones

A new organocatalytic double annulation cascade involving scission/recombination of N-O bonds of ni-trones is reported for the first time, and used to produce a range of hitherto unprecedented tricyclic bridged-fused benzo[d]azepines bearing three stereogenic centers with moderate to good yields and com-plete diastereoselectivity. A quinine-catalyzed reaction of yne-allenone esters with nitrones worked well and provided a convergent and regioselective pathway to access these three-dimensional scaffolds from the planar conjugated system. Density functional theory (DFT) calculations have been applied to under-stand the key process for forming diradical intermediates.(c) 2023 Published by Elsevier B.V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.