Oxidation of indoles with lead tetra-acetate and hydrolysis of 1,2-disubstituted indol-3-yl acetates

Abstract

Oxidation of some 1,2-disubstituted indoles with lead tetra-acetate gives the corresponding 3-acetoxy derivatives. Similar oxidation of ethyl indole-2-carboxylate affords an acetoxylated 3,3′-bi-indolyl product; methyl 1-methylindol-3-ylacetate is acetoxylated at the benzylic position of the side-chain. Alkaline hydrolysis of 1,2-disubstituted indol-3-yl acetates is accompanied by autoxidation and rearrangement to give dioxindoles, but hydrolysis of 2-ethoxycarbonyl-1-methylindol-3-yl acetate gives NN′-dimethyl derivatives of indigo and indirubin.