1-Indol-3-ylpropane-1,2-dione and related compounds

Abstract

Several routes for the preparation of 1-indol-3-ylpropane-1,2-dione, indol-3-yl methyl glyoxal, have been examined. This compound was most conveniently obtained by condensation of indolylmagnesium bromide with 2-acetoxy-propionyl chloride to give 3-(2-hydroxypropionyl)indole, which was oxidised with bismuth oxide. An alternative route involved condensation of indol-3-ylglyoxyloyl chloride with di(tetrahydropyranyl) sodiomalonate, followed by pyrolysis of the acylmalonate. Preparations of 1-(1-methyl-2-phenylindol-3-yl)- and of 1-(2-phenylindol-3-yl)-propane-1,2-dione are also described. The action of methylmagnesium iodide on these compounds, and on the ethyl ester and diethylamide of 1-methyl-2-phenylindol-3-ylglyoxylic acid, is discussed.