반응 #733712

반응 방정식

HCl

chromene carboxylate

1-(5-Ethyl-2,4-dihydroxy-phenyl)-2-(4-fluoro-phenyl)-ethanone

ethyl chlorooxoacetate

→

desired product

4-(5-Ethyl-2,4-dihydroxy-phenyl)-3-(4-fluoro-phenyl)-2,4-dioxo-butyric acid ethyl ester

용매

n-hexane

EtOAc

pyridine

반응 조건

후처리

1. 1
   추출extracted with DCM (2×100 ml)
2. 2
   세척The combined DCM layers were then washed with 2M HCl (2×80 ml), sat. NaHCO3 (1×100 ml), brine (1×100 ml)
3. 3
   건조dried with Na2SO4
4. 4
   여과After filtration and evaporation of the solvent
5. 5
   기타dark brown oil was obtained (11.4 g)

실험 절차

To a solution of 1-(5-Ethyl-2,4-dihydroxy-phenyl)-2-(4-fluoro-phenyl)-ethanone (10.3 g, 37.6 mmol) in dried pyridine (100 ml) at 0° C., ethyl chlorooxoacetate (15.4 g, 112.8 mmol) was added. The solution was stirred at 0° C. for 4 hours and at room temperature for 16 hours. The aq. layer was neutralised with 1M HCl and extracted with DCM (2×100 ml). The combined DCM layers were then washed with 2M HCl (2×80 ml), sat. NaHCO3 (1×100 ml), brine (1×100 ml) and dried with Na2SO4. After filtration and evaporation of the solvent, dark brown oil was obtained (11.4 g). Rf=0.22 (EtOAc:n-hexane/1:2). LCMS shows it is a mixture of desired product [(M−1)−=373.1, RT=7.27) and the cyclised chromene carboxylate [(M−1)−=355.4, RT=7.83) in a ratio of ca. 6:1. A small amount of sample was purified by prep. TLC for spectroscopic analysis. 1H NMR (d6-acetone) δ=7.75 (1H, s); 7.30 (2H, m); 7.00 (1H, m); 6.45 (1H, s); 4.65 (1H, s); 4.25 (2H, q); 2.55 (2H, q) and 1.10 (6H, t)

출처