Nitrogen → 1-[4-(2-Methyl-[1,3]dioxolan-2-yl)-butyl]-3-nitro-1H-pyrazole

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In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of 5-nitro-1H-pyrazole (2.97 g, 18.68 mmol) and Cs2CO3 (6.67 g, 26.22 mmol) in AcCN (27.0 mL) was treated with a solution of 2-(4-bromo-butyl)-2-methyl-[1,3]dioxolane (5.85 g, 26.22 mmol) in AcCN (27.0 mL). The reaction mixture was stirred at 80° C. for 2.5 h. Water (100 mL) and EA (200 mL) were added to the cooled reaction mixture. The aq. layer was extracted with EA (100 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure. Purification of the residue by FC (60:40 hept-EA) gave the title compound. TLC: rf (60:40 hept-EA)=0.17. LC-MS-conditions 02: tR=0.89 min; [M+H]+=256.32. 1H NMR (400 MHz, CDCl3) δ 1.31 (s, 3H), 1.39-1.50 (m, 2H), 1.67-1.75 (m, 2H), 1.92-2.02 (m, 2H), 3.88-3.94 (m, 2H), 3.94-4.00 (m, 2H), 4.22 (t, J=7.0 Hz, 2H), 6.91 (d, J=2.3 Hz, 1H), 7.46 (d, J=2.3 Hz, 1H).

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