[Cl:1][C:2]1[CH:7]=[CH:6][C:5]([C:8]2[CH:13]=[CH:12][C:11]([CH2:14][CH3:15])=[C:10]([CH:16]3[C:21](=[O:22])[C:20]([CH3:24])([CH3:23])[O:19][C:18]([CH3:26])([CH3:25])[C:17]3=[O:27])[CH:9]=2)=[CH:4][CH:3]=1.C(N(CC)CC)C.[C:35](Cl)(=[O:40])[C:36]([CH3:39])([CH3:38])[CH3:37]>ClCCl>[Cl:1][C:2]1[CH:3]=[CH:4][C:5]([C:8]2[CH:13]=[CH:12][C:11]([CH2:14][CH3:15])=[C:10]([C:16]3[C:21](=[O:22])[C:20]([CH3:24])([CH3:23])[O:19][C:18]([CH3:26])([CH3:25])[C:17]=3[O:27][C:35](=[O:40])[C:36]([CH3:39])([CH3:38])[CH3:37])[CH:9]=2)=[CH:6][CH:7]=1To a solution of 4-(4′-chloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethylpyran-3,5-dione (0.077 g, 0.20 mmol) dissolved in anhydrous dichloromethane (3 ml) is added triethylamine (0.031 ml, 0.22 mmol) then pivaloyl chloride (0.027 ml, 0.22 mmol). This mixture is stirred at room temperature for 3 hours, then diluted with dichloromethane (15 ml) and washed with distilled water (2×10 ml). Organic fractions are combined, dried over magnesium sulphate, then concentrated to give a crude oil which is purified by flash chromatography (100% hexane to hexane/ethyl acetate 9:1 ratio) to afford 2,2-dimethylpropionic acid 4-(4′-chloro-4-ethylbiphenyl-3-yl)-2,2,6,6-tetramethyl-5-oxo-5,6-dihydro-2H-pyran-3-yl ester (0.090 g) as a colourless gum.
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