The chemistry of indoles. XXIV. Syntheses of 3-indoleacetic acid and 3-indoleacetonitrile having a halogeno group and a carbon functional group at the 4-position.

Abstract

Various 4-halogeno-3-indoleacetic acids and -3-indoleacetonitriles were synthesized for the first time by means of the Sandmeyer or Schiemann reaction, demonstrating the versatility of 4-indolediazonium salts in 4-substituted indole chemistry. A practical synthetic method for 4-halogenoindoles was developed by regio-selective thallation-halogenation, and the products were also led to 4-halogeno-3-indoleacetic acids. The first synthesis of 4-formyl-3-indoleacetonitrile is also reported.