Abstract
The Vilsmeier-Haack reaction of 2-ethoxycarbonyl-1-hydroxyindole (2) did not give 3-formylindoles but gave 3-chloro-2-ethoxycarbonylindole (3). The electrophilic reaction of 2 with quinoline 1-oxide (4) in the presence of benzoyl chloride or tosyl chloride also failed, 1-benzoyloxy-2-ethoxycarbonylindole (6) or 3 being formed, respectively. The reaction of 2 with tosyl chloride, benzoyl chloride or acetic anhydride gave the corresponding 3-acyloxy-2-ethoxycarbonylindoles (7, 8 and 11) in unsatisfactory yields. Treatment of 2 with tosyl chloride and 1-morpholinocyclohexene in pyridine-dimethylformamide afforded 2-ethoxycarbonyl-3-(2-oxocyclohexyl) indole (13) after hydrolysis of the reaction mixture.
