Allyl bromide → 1H-Pyrazole-5-acetic acid, 1-methyl-4-nitro-α-2-propen-1-yl-, methyl ester

Participants

Reaction Conditions

Reaction Steps

To a solution of methyl 2-(2-methyl-4-nitro-pyrazol-3-yl)acetate (869 mg, 4.36 mmol) in anhydrous DMF (10 mL) was added at 0° C. sodium hydride (218 mg, 5.45 mmol, 60 mass %), the mixture became dark red right away. After stirring at 0° C. for 15 min, allyl bromide (0.57 mL, 6.54 mmol) was added slowly, stirred at 0° C. for 10 min then room temp for 1 h. The reaction was quenched with water (20 mL) and extracted with EA (200 mL, 50 mL). Combined organic layer was washed with water (15×3 mL), brine (10 mL), dried (MgSO4) and the solvent removed under reduced pressure. The residue was purified via silica gel chromatography (0-100% EtOAc/heptane) to afford methyl 2-(2-methyl-4-nitro-pyrazol-3-yl)pent-4-enoate (713 mg, 68%). 1H NMR (400 MHz, CDCl3) δ 8.10 (s, 1H), 5.71-5.54 (m, 1H), 5.01 (d, J=13.1 Hz, 2H), 4.43 (dd, J=9.8, 5.5 Hz, 1H), 3.86 (s, 3H), 3.72 (s, 3H), 3.14-3.02 (m, 1H), 2.79-2.62 (m, 1H).

Provenance & Evidence