Synthesis and Transformations of Ethyl 3-(Benzoylamino)-1H-indole-2-carboxylates

Abstract

A number of ethyl 3-(benzoylamino)-1H-indole-2-carboxylates were prepared by heating ethyl 2-(benzoylamino)-3-(phenylhydrazono)propanoates with polyphosphoric acid. The reaction of ethyl 3-(benzoylamino)-5-chloro-1H-indole-2-carboxylate with hydrazine hydrate resulted in the formation of the debenzoylated hydrazide. Hydrolysis of the same ester with aqueous sodium hydroxide afforded 3-(benzoylamino)-5-chloro-1H-indole-2-carboxylic acid, which on heating underwent a decarboxylation reaction to give N-(5-chloro-1H-indol-3-yl)benzamide.

Key words

hydrazones - indoles - cyclization - Fischer indole synthesis - rearrangement

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