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

Abstract

Abstractmagnified imageAn 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.