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.