反应详情

A solution of the product of Example 6B (12.8 g, 51.2 mmol) in ethylene glycol (200 mL) was heated at reflux for 6 hours, cooled to ambient temperature, stirred for 16 hours at ambient temperature, then heated at reflux for an additional 3 hours. After cooling, the reaction mixture was poured into water (100 mL) and extracted with diethyl ether (250 mL). The mixture was partitioned and the organic portion was concentrated. The resulting residue was purified by silica gel chromatography (gradient elution, 0%-20% EtOAc/hexanes) to obtain the title compound (3.62 g, 28% for three steps). 1H NMR (300 MHz, CDCl3) δ 7.86 (dd, J=8.1, 1.7 Hz, 1H), 7.44 (d, J=7.8 Hz, 1H), 7.05-6.98 (m, 1H), 4.66-4.60 (m, 2H), 2.90-2.84 (m, 2H).

1. temperatureat reflux for 6 hours
2. temperatureheated
3. temperatureat reflux for an additional 3 hours
4. temperatureAfter cooling
5. extractionextracted with diethyl ether (250 mL)
6. customThe mixture was partitioned
7. concentrationthe organic portion was concentrated
8. customThe resulting residue was purified by silica gel chromatography (gradient elution, 0%-20% EtOAc/hexanes)