1,1-Dichloroethane → 1-Cyclopropyl-4-nitro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A 100-mL three-neck round-bottomed flask equipped with a reflux condenser and magnetic stirrer was purged with nitrogen and charged with 4-nitropyrazole (500 mg, 4.42 mmol), cyclopropylboronic acid (760 mg, 8.84 mmol), sodium carbonate (937 mg, 8.84 mmol), 2,2′-bipryidyl (690 mg, 4.42 mmol), and dichloroethane (45 mL). After bubbling nitrogen through the resulting suspension for 30 min, copper (II) acetate (802 mg, 4.42 mmol) was added, and the reaction mixture was heated at 70° C. (oil bath temperature) for 6 h. After this time, the mixture was cooled to room temperature and filtered. The filtrate was diluted with ethyl acetate (150 mL) and water (30 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (3×50 mL). The combined organic layers were dried over sodium sulfate and concentrated under reduced pressure. The residue was purified by column chromatography (silica, 0% to 50% ethyl acetate/hexanes) to afford a 37% yield (185 mg) of 109a as an off-white solid: mp 44-45° C.; 1H NMR (500 MHz, CDCl3) δ 8.18 (s, 1H), 8.03 (s, 1H), 3.67 (s, 1H), 1.16 (m, 4H); MS (APCI+) m/z 154.1 (M+H).

Provenance & Evidence