Ammonium Chloride → 2-tert-butoxycarbonyloxy-4-[3-(1-tert-butoxycarbonyl-1H-pyrrol-2-yl)-3-hydroxy-prop-1-ynyl]-5-fluoro-indole-1-carboxylic acid tert-butyl ester

Participants

Reaction Steps

A solution of 2-tert-butoxycarbonyloxy-5-fluoro-4-iodo-indole-1-carboxylic acid tert-butyl ester (from Example 2 above) (9.85 g, 20.0 mmol), and 2-(1-hydroxy-prop-2-ynyl)-pyrrole-1-carboxylic acid tert-butyl ester (from Example 1 above) (7.96 g, 36.0 mmol) in dry THF (85 mL) and triethylamine (Aldrich, 85 mL) was degassed by bubbling argon through the solution for 15 minutes. At this time copper(I) iodide (0.61 g, 3.2 mmol) and (Ph3P)4Pd (Aldrich, 1.85 g, 1.6 mmol) were added, and the reaction mixture was stirred at room temperature for 3.5 hours. The reaction mixture was then poured into a saturated aqueous ammonium chloride solution (100 mL) and extracted with ethyl acetate (3×150 mL). The combined organic extracts were successively washed with water (100 mL) and brine (100 mL), dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. Flash chromatography (Biotage, 75-S, 9/1 hexanes/ethyl acetate) afforded 2-tert-butoxycarbonyloxy-4-[3-(1-tert-butoxycarbonyl-1H-pyrrol-2-yl)-3-hydroxy-prop-1-ynyl]-5-fluoro-indole-1-carboxylic acid tert-butyl ester as a light orange amorphous solid. (Yield 9.5 g, 83%).

Provenance & Evidence