反应详情

A flask fitted with a Dean-Stark trap was charged with a solution of 5-chloro-2-fluoronicotinaldehyde, 27, (8.95 g, 56.10 mmol) and 2,3-dimethylbutane-2,3-diol (8.00 g, 67.70 mmol) and p-toluene sulfonic acid mono hydrate (0.54 g, 2.81 mmol) in toluene (250 mL) and heated to vigorous reflux for 3 hr. The mixture was cooled, diluted with EtOAc, washed with NaHCO3 (2×) and brine (1×). The organic phase was dried over Na2SO4, filtered through a silica plug and concentrated in vacuo. A crystalline solid formed on standing (14.47 g): 1H NMR (300.0 MHz, CDCl3) δ 8.12 (s, 1H), 7.97 (dd, J=2.7, 7.8 Hz, 1H), 6.08 (s, 1H), 1.33 (s, 3H) and 1.26 (s, 3H) ppm.

1. customA flask fitted with a Dean-Stark trap
2. temperatureheated
3. temperatureto vigorous reflux for 3 hr
4. temperatureThe mixture was cooled
5. washwashed with NaHCO3 (2×) and brine (1×)
6. dry with materialThe organic phase was dried over Na2SO4
7. filtrationfiltered through a silica plug
8. concentrationconcentrated in vacuo
9. customA crystalline solid formed