Citric Acid → 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(3-phenylprop-2-en-1-yl)-1,1,2-(R)-pentanetricarboxylate

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Reaction Steps

0.048 g of 60% sodium hydride was added to a stirred solution of 0.45 g of 1,2-dibenzyl 1-tert-butyl 4-methyl-1,1,2-(R)-pentanetricarboxylate in 10 ml of dry dimethylformamide under a nitrogen atmosphere. The mixture was stirred for 0.75 hour at 0° and for a further 2.5 hours at room temperature. The mixture was again cooled to 0° before the addition of 0.236 g of cinnamyl bromide. After allowing the mixture to return slowly to room temperature, the solution was stirred at room temperature for 2 days. The mixture was poured into 5% aqueous citric acid solution and the product was extracted four times with diethyl ether. The combined ether extracts were washed with water and sodium chloride solution and dried over anhydrous magnesium sulfate. The solvent was removed by evaporation and the residue was purified by flash chromatography on silica gel using hexane/ether (9:1) for the elution. There was obtained 0.542 g of 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(3 -phenylprop-2-en-1-yl)-1,1,2-(R)-pentanetricarboxylate in the form of a colorless oil; MS: 571 (M+H)+.

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