Reactions of arenesulphonyl azides with some di- and tri-substituted indoles

Abstract

3-Ethyl-2-methylindole reacted with tosyl azide forming 3-ethyl-2-methyl-3-p-tolylsulphonylamino-3H-indole in good yield; 3-methyl-2-phenylindole formed the analogous compound in moderate yield; and 2-ethyl-3-methylindole formed 2-ethyl-3-methyl-3-p-tolylsulphonylamino-3H-indole in very poor yield. The other products of this reaction were separated and characterised. The reaction of 3-ethyl-1,2-dimethylindole with tosyl azide was similar to that reported¹ for 1,2,3-trimethylindole. In contrast the reaction of 2-ethyl-1,3-dimethylindole with the azide yielded a large number of products. 1,2,3,4-Tetrahydrocyclopent[b]indole and its N-methyl derivative react rapidly with tosyl azide.

Some of the indoles were treated with p-chlorobenzenesulphonyl azide to provide further examples of this type of reaction.