反应详情

温度

37.5 °C

A 22 L 4-neck flask equipped with a mechanical stirrer, thermowell, addition funnel, condenser and N2 inlet was charged with 4-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (17, 1.42 kg, 7.32 mol), toluene (9.5 L) and ethyl vinyl ether (18, 790.5 g, 1050 mL, 10.98 mol, 1.50 equiv). A 4 M HCl in dioxane (50 mL) was added via an addition funnel over 10 minutes and the resulting reaction mixture was heated at 35-40° C. for 7 hr to give a clear homogeneous solution. When the reaction was shown to be complete by GC, solid NaHCO3 (130 g) was added and the mixture was stirred for 1 hr before being filtered. The filtrate was concentrated under reduced pressure. Heptane (200 mL) was added to the residue to affect crystallization. The solid was collected by filtration and dried in a vacuum oven to afford 1-(ethoxyethyl)-4-(4,4,5,5-tetramethyl[1,3,2]dioxaborolan-2-yl)-1H-pyrazole (19, 1.896 Kg, 1.948 Kg theoretical, 97.3%) as a white to off-white solid. For 19: 1H NMR (DMSO-d6, 400 MHz) δ ppm 8.09 (s, 1H), 8.58 (s, 1H), 7.62 (s, 1H), 5.55 (q, 1H, J=6.1 Hz), 3.37 (dq, 1H, J=7.1, 9.6 Hz), 3.12 (dq, 1H, J=7.0, 9.7 Hz), 1.56 (d, 3H, J=6.0 Hz), 1.24 (s, 12H), 1.00 (t, 3H, J=7.0 Hz); C13H23BN2O3 (MW, 266.14), LCMS (EI) m/e 267 (M++H).

1. customA 22 L 4-neck flask equipped with a mechanical stirrer
2. additionthermowell, addition funnel, condenser and N2 inlet
3. customthe resulting reaction mixture
4. customto give a clear homogeneous solution
5. additionwas added
6. filtrationbefore being filtered
7. concentrationThe filtrate was concentrated under reduced pressure
8. additionHeptane (200 mL) was added to the residue
9. customcrystallization
10. filtrationThe solid was collected by filtration
11. customdried in a vacuum oven