Green oxidative rearrangement of indoles using halide catalyst and hydrogen peroxide

Oxidative rearrangement of indoles is an essential transformation that has been widely used in the synthesis of many pharmaceutical agents and bioactive natural products. Herein, we report an efficient, practical and metal-free method for the oxidative rearrangement of indoles to spirooxindoles, 2-oxindoles, 2,2-disubstituted indolin-3-ones, and oxa-spirooxindoles using 10 mol% HBr and hydrogen peroxide as the terminal oxidant. The protocol displays a broad substrate scope (35 examples) and a wide range of functional group tolerance and has been applied in the synthesis of (±)-coerulescine and the formal synthesis of (±)-horsfiline. Notably, the distinct advantages of this protocol involve metal-free catalysis, waste prevention, and simple operation. To create your abstract, type over the instructions in the template box below.Fonts or abstract dimensions should not be changed or altered.