A novel synthesis of indole derivatives by the reaction of N-arylhydroxamic acids with malononitrile

Abstract

(Chemical Equation Presented) An approach to indole derivatives from N-arylhydroxamic acids and malononitrile via a [3,3]-sigmatropic rearrangement and intramolecular cyclization is described. Reactions of N-arylhydroxamic acids 1a-c, 2a-c and 3a-c with malononitrile in the presence of triethylamine at room temperature gave the corresponding α-cyanoacetamide derivatives 4a-c, 5a-c, 6a-c, 7a-c and 8a-c. Thermal treatment of 4a-c, 5a-c and 7a-c with a base, e.g. triethylamine and sodium methoxide, caused intramolecular cyclization and deacylation to afford the corresponding indole derivatives 9-11.