Acid-catalysed cyclization of α-oxo-anilides to 1,3-dihydro-3-hydroxyindol-2-ones
Abstract
N-Alkyl-α-oxo-anilides undergo acid-catalysed cyclization at 25 °C to give the corresponding 1,3-dialkyl-1,3-dihydro-3-hydroxyindol-2-ones in high yields. The same anilides give 1,3-dialkyl-3-chloro-1,3-dihydroindol-2-ones, when treated with concentrated hydrochloric acid at 80°C. Reduction of the hydroxyindolones yields 1,3-dialkylindoles.