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温度

0 °C

To an ice-cold solution of concentrated sulphuric acid (6 ml) is added a second solution of 2-(2′,4′-dichloro-4-ethylbiphenyl-3-yl)-4,4,6,6-tetramethyl-1,5-dioxaspiro[2.4]heptan-7-one (1.90 g, 0.0045 mol) in 1,2-dichloroethane (6 ml) dropwise over 5 mins. This biphasic mixture is stirred vigorously for 2 hours at 0° C., then is poured into ice and extracted with diethyl ether. All organics are combined, washed with brine, dried over magnesium sulfate then concentrated in vacuo. The crude product is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane) to afford 4-(2′,4′-dichloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione as a yellow gum.

1. additionis poured into ice
2. extractionextracted with diethyl ether
3. washwashed with brine
4. dry with materialdried over magnesium sulfate
5. concentrationthen concentrated in vacuo
6. customThe crude product is purified by flash column chromatography (5% ethyl acetate in isohexane to 25% ethyl acetate in isohexane)