Urea → N-[2-(Diethylamino)ethyl]-1H-indole-2-carboxamide

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Reaction Steps

To a suspension of 4.83 g indol-2-carboxylic acid and 3.8 g N-hydroxy-succinimide in 60 ml abs. acetonitrile is added at room temperature a solution of 6.8 g dicyclohexyl-carbodiimide in 30 ml abs. diethyl ether, whereby the temperature rises rapidly to 33°. The suspension goes into solution and urea precipitates. The mixture is stirred at room temperature for 3 hours, filtered and the filtrate washed with acetonitrile. The filtrate is treated dropwise with 8.5 ml (60 mM) diethyl-aminoethyl amine, whereby the temperature rises from 20° to 28°. The mixture is left overnight and then is partitioned between 1N aqueous sodium carbonate solution and CH2Cl2. The organic phase is evaporated to give the title compound, recrystallised from CH2Cl2 /hexane m.p. 133°-134°.

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