The reactions of intermediates derived from the chlorination of indoles

Abstract

The various steps involved in the reaction of indoles with sodium hypochlorite have been studied. At low temperatures, these reactions lead to the formation of 3-chloroindolenine. The 3-chloroindolenines have been found to be thermally labile. For example, 2,3-dimethyl-3-chloroindolenine rapidly rearranges to an isomeric compound at 15°. Selective reactions of 3-chloroindolenines with silver ion in methanol have been shown to produce 3-methoxyindolenines in high yield. In contrast, the rearranged isomer of 2,3-dimethyl-3-3-chloroindolenine has been shown to give high yields of indole derivatives which are functionalized in the 2-position. The rearrangements of the tosylate or p-nitrobenzoate of 1-hydroxy indoles have been found to result in the formation of the respective tosylate or p-nitrobenzoate of the 3-hydroxyindolenine.