Temperature-Dependent Product Selectivity in the VilsmeierHaack Reaction on Bis(phenylhydrazones) of Bis(aroylmethyl) Sulfides (=1,1′-[Thiobis(methylene)]bis[arylmethanone] Bis(2-phenylhydrazones)): Synthesis of 3-Aroylindoles (=Aryl(1H-indol-3-yl)methanones)

The bis(phenylhydrazone) of substituted diphenacyl sulfides (=1,1-[thiobis(methylene)]bis[arylmethanone] bis(2-phenylhydrazones)) 1 underwent a tandem sequence of reactions upon treatment with Vilsmeier reagent, ultimately yielding 3-aroylindoles (=aryl(1H-indol-3-yl)methanones) 3 (Scheme1 and Table1). The reaction seems to be product selective depending upon the reaction temperature.