Asymmetric Synthesis of Spirobenzazepinones with Atroposelectivity and Spiro‐1,2‐Diazepinones by NHC‐Catalyzed [3+4] Annulation Reactions

Abstract

AbstractA strategy for the NHC‐catalyzed asymmetric synthesis of spirobenzazepinones, spiro‐1,2‐diazepinones, and spiro‐1,2‐oxazepinones has been developed via [3+4]‐cycloaddition reactions of isatin‐derived enals (3C component) with in‐situ‐generated aza‐o‐quinone methides, azoalkenes, and nitrosoalkenes (4atom components). The [3+4] annulation strategy leads to the seven‐membered target spiro heterocycles bearing an oxindole moiety in high yields and excellent enantioselectivities with a wide variety of substrates. Notably, the benzazepinone synthesis is atroposelective and an all‐carbon spiro stereocenter is generated.