Potassium Carbonate → 1-((R)-2,2-dimethyl-[1,3]dioxolan-4-ylmethyl)-3-nitro-1H-pyrazole

Participants

Reaction Conditions

Reaction Steps

A solution of 3-nitro-1H-pyrazole (prepared as in Example 5, 12.0 g, 106 mmol) in N,N-dimethylformamide (150 mL) was treated with toluene-4-sulfonic acid (S)-2,2-dimethyl-[1,3]dioxolan-4-yl-methyl ester (25.5 g, 89.0 mmol), and potassium carbonate (24.5 g, 178 mmol). The reaction mixture was stirred for 6 h at 90° C., under nitrogen. The reaction mixture was diluted with ethyl acetate, washed with water twice, a saturated sodium chloride solution and dried over sodium sulfate. The organic layer was concentrated, and the crude product was purified by ISCO flash chromatography (Teledyne Isco RediSep Flash Column 330 g, 5% to 30% ethyl acetate/hexanes) to afford 1-((R)-2,2-dimethyl-[1,3]dioxolan-4-yl-methyl)-3-nitro-1H-pyrazole (14.5 g, 72%) as light yellow oil: LR-ES-MS m/z calculated for C9H13N3O4 [M]+ 227, observed [M+H]+ 228. 1H NMR (300 MHz, CDCl3) δ ppm 1.35 (s, 3H), 1.40 (s, 3H), 3.77 (dd, J=8.8, 5.7 Hz, 1H), 4.13 (dd, J=8.8, 6.6 Hz, 1H), 4.27 (dd, J=14.0, 6.6 Hz, 1H), 4.39 (dd, J=14.0, 3.6 Hz, 1H), 4.45-4.59 (m, 1H), 6.92 (d, J=2.4 Hz, 1H), 7.59 (d, J=2.4 Hz, 1H)

Provenance & Evidence