反应详情

In a flame dried round-bottomed flask equipped with a magnetic stir bar and under inert atmosphere (N2), a solution of [5-(2-methyl-[1,3]dioxolan-2-yl)-furan-2-yl]-methanol (6.00 g, 32.58 mmol) in dry CH2Cl2 (60.0 mL) was treated at 0° C. with Et3N (5.89 mL, 42.35 mmol) followed by DMAP (398 mg, 3.26 mmol) and Ms-Cl (3.03 mL, 39.09 mmol). The reaction mixture was stirred at rt for 2 h before being quenched with water (60 mL), extracted with CH2Cl2 (60 mL) and the combined org. extracts were dried over MgSO4, filtered, and the solvents were removed under reduced pressure to give 6.66 g of crude 2-(5-chloromethyl-furan-2-yl)-2-methyl-[1,3]dioxolane as an orange oil. A solution of the crude material in acetone (82.0 mL) was treated, under inert atmosphere (N2) with K2CO3 (13.50 g, 97.71 mmol) followed by 5-nitro-1H-pyrazole (3.68 g, 32.57 mmol) and TBA bromide (2.10 g, 6.51 mmol). The resulting mixture was stirred overnight at rt. Water (50 mL) and EA (75 mL) were added. 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 as a yellow oil. TLC: rf (60:40 hept-EA)=022. LC-MS-conditions 02: tR=0.92 min; [M+H]+=280.04. 1H NMR (400 MHz, CDCl3) δ 1.71 (s, 3H), 3.95-4.02 (m, 2H), 4.02-4.09 (m, 2H), 5.36 (s, 2H), 6.33 (d, J=3.3 Hz, 1H), 6.41 (d, J=3.0 Hz, 1H), 6.91 (d, J=2.5 Hz, 1H), 7.48 (d, J=2.3 Hz, 1H).

1. custombefore being quenched with water (60 mL)
2. extractionextracted with CH2Cl2 (60 mL)
3. dry with materialextracts were dried over MgSO4
4. filtrationfiltered
5. customthe solvents were removed under reduced pressure