Acetic acid, azido-, ethyl ester → methyl 6-fluoro-4-methoxy-1H-indole-2-carboxylate

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Reaction Conditions

Reaction Steps

Sodium methoxide solution (25% by weight in methanol, 22.25 mL) and methanol (52 mL) were added to a flask and cooled to −20° C. using an acetonitrile/dry ice bath. Ethyl 2-azidoacetate (25% by weight in ethanol, 50.3 g) and 4-fluoro-2-methoxybenzaldehyde (5.00 g, dissolved in ethyl 2-azidoacetate solution) were added drop-wise to the stirring sodium methoxide solution at −20° C. The solution was then stirred at −20° C. for 3.5 hours, then at 0° C. for one hour. The solution was poured over ice, vacuum filtered, and washed with water. The filtered solid was taken up in xylenes (100 mL), washed twice with brine, and dried using anhydrous sodium sulfate and filtered. In a separate flask xylenes (50 mL) was brought to reflux. The xylene solution containing the filtered material was added drop-wise to the refluxing xylenes. The solution was then refluxed for five hours, cooled, and placed in a freezer for 16 hours. The precipitate was filtered out. The volume of the filtrate was reduced on vacuum to generate a second crop of precipitate, which was washed with hexanes, then 5% ethyl acetate in hexanes and combined with material from the first filtration.

Provenance & Evidence