Rhodium-Catalyzed Cycloadditions between 3‑Diazoindolin-2-imines and 1,3-Dienes

Azepino­[2,3-b]­indoles were regioselectively prepared through rhodium-catalyzed formal aza-[4 + 3] cycloaddition between 3-diazoindolin-2-imines and 1,3-dienes in moderate to good yields. Using 2-[(trimethylsilyl)­oxy]-1,3-butadiene as the diene component, azepino­[2,3-b]­indol-4­(1H)-ones were constructed. Furthermore, the reactions of cyclic dienes, such as 1,3-cyclohexadiene and 1,3-cyclopentadiene, furnished the corresponding [3 + 2] cycloaddition products.