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

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Reaction Steps

A solution of 2.47 g of 1,2-dibenzyl 1-tert.butyl 4-methyl-1-(prop-2-en-1-yl)-1,1,2(R)-pentanetricarboxylate in 5 ml of dry diethyl ether was cooled to 0° and 0.325 ml of monochloroborane-methyl sulphide complex was added. The mixture was stirred at room temperature for 2 hours, then cooled to 0° and 0.5 ml of water, 2.3 ml of 1.5M aqueous sodium hydroxide solution and 2.3 ml of 30% aqueous hydrogen peroxide were added. The mixture was stirred at room temperature for 3 hours and then acidified with 5% aqueous citric acid solution. The product was extracted with diethyl ether and the extract was washed with saturated sodium chloride solution, dried over anhydrous magnesium sulfate and evaporated. The residue was purified by flash chromatography on silica gel using hexane/ethyl acetate (5:1) for the elution. There were obtained 1.098 g of 1,2-dibenzyl 1-tert.butyl 1-(3-hydroxypropyl)-4-methyl-1,1,2(R)-pentanetricarboxylate in the form of a colorless oil; MS: 513 (M+H)+.

Provenance & Evidence