1H-Indole-5-Carboxylic Acid → tert-butyl 4-(1H-indol-5-ylcarbonyl)piperazine-1-carboxylate

Participants

Reaction Steps

To a solution of 1H-indole-5-carboxylic acid (323 mg, 2.0 mmol) in 10 mL of DCM was added DIPEA (1.03 g, 8.0 mmol) and piperazine-1-carboxylic acid tert-butyl ester (400 mg, 2.1 mmol). HBTU (1.14 g, 3.0 mmol) was added at 0° C. The resulting mixture was stirred at r.t. for 18 h. TLC indicated that the starting material was gone. The mixture was diluted with DCM (100 mL) and washed with water (30 mL). The organic layer was separated and dried over anhydrous Na2SO4. The solution was concentrated to give a crude product, which was then purified with silica gel column (Hexane/EtOAc=1/1) to give HJC-2-13 (605 mg, 92%) as a yellow oil. 1H NMR (600 MHz, CDCl3) δ 8.44 (s, 1H), 7.73 (s, 1H), 7.40 (d, 1H, J=8.4 Hz), 7.26-7.27 (m, 2H), 6.59 (s, 1H), 3.56-3.63 (m, 4H), 3.42-3.47 (m, 4H), 1.47 (s, 9H).

Provenance & Evidence