Triphenylphosphine → 4-(furan-3-ylmethoxy)-1H-indole-2-carboxylic acid ethyl ester

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Reaction Steps

DEAD (2.1 ml, 13.65 mmol) is slowly added to a solution of 4-hydroxy-1H-indole-2-carboxylic acid ethyl ester 79 (2 g, 9.75 mmol), triphenylphosphine (3.58 g, 13.65 mmol) and furan-3-yl-methanol (1.18 ml, 12.26 mmol) in 10 ml of THF, so that the temperature always remained below 30° C. Stirring is continued for 2 hours and the solvent is then evaporated. The crude residue is triturated with ether and the white precipitate is filtered off. It contained mainly product. The mother liquor is purified by chromatography (cyclohexane:EtOAc/95:5) and combined with the first precipitate. Yield: 3 g (>100%).

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