Further examination of the reactions of simple indoles with arenesulphonyl azides

Abstract

3-Methylindole reacts readily in pyridine solution with p-chloro- and with p-nitro-benzenesulphonyl azides to give 1 : 2 reaction products; from the reactions between p-nitrobenzenesulphonyl azide and 3-methylindole in acetic acid solution a 1 : 1 reaction product has been isolated. Similar reactions of ethyl 1-methylindole-2-carboxylate yield ethyl 3-arylsulphonylaminoindole-2-carboxylates and these compounds, on hydrolysis and decarboxylation, give 3-arylsulphonylamino-1-methylindoles.

The properties of the product obtained by treating indole with tosyl azide can be adequately explained in terms of a tautomeric mixture of amino and imino forms of the former.