2,2'-Bipyridine → 1-Cyclopropyl-3-nitro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A 250-mL three-neck round-bottomed flask equipped with a reflux condenser and magnetic stirrer was purged with nitrogen and charged with 3-nitro-(1H)pyrazole (1.30 g, 11.5 mmol), cyclopropylboronic acid (1.98 g, 23.0 mmol), sodium carbonate (3.66 g, 34.5 mmol), 2,2′-bipyridyl (3.58 g, 23.0 mmol), dichloroethane (60 mL) and copper(II) acetate (2.08 g, 11.5 mmol). The reaction mixture was heated at 70° C. (oil bath temperature) for 3 h. After this time, another portion of cyclopropyl boronic acid (1.98 g, 23.0 mmol) was added, and the mixture was heated for 3 h. After this time, the mixture was cooled to room temperature and filtered. The filtrate was diluted with ethyl acetate (350 mL) and water (40 mL). The organic layer was separated, and the aqueous layer was extracted with ethyl acetate (3×150 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 100% ethyl acetate/hexanes) to afford an 85% yield (1.49 g) of 123a as a colorless oil: 1H NMR (500 MHz, CDCl3) d 7.53 (d, 1H, J=2.4 Hz), 6.87 (d, 1H, J=2.5 Hz), 3.71 (m, 1H), 1.25 (m, 2H), 1.12 (m, 2H); MS (APCI+) m/z 154.1 (M+H).

Provenance & Evidence