Synthesis of Indole‐ and Pyrrole‐Fused Seven‐Membered Nitrogen Heterocycles via Acid‐Base Switchable Cyclization Involving Cleavage of Amide C−N Bonds

Abstract We report the method for synthesis of indole‐ and pyrrole‐fused seven‐membered nitrogen heterocycles by means of acid‐base switchable cyclization reactions. The reactions involved cleavage of amide C−N bonds, chemoselective N‐1 or C‐3 acylation, and 1,4‐Michael addition. This method could be used to construct two different kinds of seven‐membered rings in one step from the same starting material without the need for a transition‐metal catalyst. magnified image