Ethylenediamine → 6-cyclopropyl-1H-indazole

Participants

Reaction Steps

In a round-bottomed flask, 6-cyclopropyl-1-(2-trimethylsilanyl-ethoxymethyl)-1H-indazole (668 mg, 2.2 mmol) was dissolved in dichloromethane (12 ml) and trifluoroacetic acid (6.5 ml, 84.4 mmol) was added. The yellow reaction mixture was stirred at room temperature for 2.25 h then concentrated. The residue was redissolved in dichloromethane (12 ml) and ethylenediamine (9.0 ml, 133 mmol) was added. The solution was stirred at room temperature for 1 h then quenched with water and extracted with EtOAc (2×). The combined organic layers were washed with water and brine then dried over sodium sulfate, filtered and concentrated. The residue was chromatographed over silica gel with EtOAc/Hexanes (gradient 0-25% EtOAc) to provide 317 mg (91%) of 6-cyclopropyl-1H-indazole as a light yellow solid. 1H NMR (CDCl3, 300 MHz): δ (ppm) 7.99-8.08 (m, 1H), 7.59-7.70 (m, 1H), 7.16-7.25 (m, 1H), 6.88-7.01 (m, 1H), 1.94-2.14 (m, 1H), 0.96-1.11 (m, 2H), 0.71-0.84 (m, 2H).

Provenance & Evidence