A mixture of 5-hydroxy-1H-indole-2-carboxylic acid ethyl ester (2 g, 10 mmol), 2-chloro-N,N-dimethylacetamide (1.33 g, 11 mmol) and cesium carbonate (9.8 g, 30 mmol) ) in dimethylformamide (20 mL) was stirred at room temperature for 16 hours. The reaction was diluted with ethyl acetate (150 mL), washed with water (5×50 mL) and brine, dried and concentrated. The residue was recrystallized from ethyl acetate and hexane to give 1.4 g of 5-dimethylcarbamoylmethoxy-1H-indole-2-carboxylic acid ethyl ester as a brown solid.
