1-Hydroxybenzotriazole → 5-(4-tert-butoxycarbonyl-[1,4]diazepane-1-carbonyl)-1H-indole-2-carboxylic acid ethyl ester

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Reaction Steps

To a solution of 1H-indole-2,5-dicarboxylic acid 2-ethyl ester (3.08 g, 13 mmol) and tert-butyl 1-homopiperazine-carboxylate (1 eq., 2.657 g) in DMF (50 ml) was added N-hydroxybenzotriazole (0.2 eq., 360 mg). After a five minutes, N-(3-dimethylaminopropyl)-N′-ethyl-carbodiimide hydrochloride (1.2 eq., 3.05 g) was added and the mixture stirred at room temperature overnight. The solvent was removed under reduced pressure and the crude product was purified by column chromatography on silica gel (3:1 heptane/ethyl acetate eluant) to afford the product as a light-brown solid (5.21 g, 94%). MS (m/z): 416.4 (M+H)+.

Provenance & Evidence