Benzyl Chloride → D-leucic acid benzyl ester

Participants

Reaction Steps

264.0 g. of (R)-2-hydroxy-isocaproic acid were dissolved in 1.8 litres of absolute dioxan in a three-necked flask fitted with a stirrer, thermometer annd reflux condenser with a calcium chloride tube. The solution was treated successively with 285 ml. of triethylamine and 236 ml. of benzyl chloride and heated at an internal temperature of 100° for 20 hours with stirring in an oil-bath. After cooling, the resulting triethylamine hydrochloride was filtered off and washed with 500 ml. of ethyl acetate. The filtrate was evaporated under reduced pressure at 50°. The residual oil was dissolved in 800 ml. of ethyl acetate and washed twice with 150 ml. portions of 3-N hydrochloric acid, twice with 100 ml. portions of 5% sodium chloride solution, twice with 150 ml. portions of 10% potassium bicarbonate solution and twice with 100 ml. portions of 5% sodium chloride solution. After each of these washings, the oil was rinsed with 200 ml. of ethyl acetate. The ethyl acetate solutions were dried over magnesium sulphate and evaporated under reduced pressure at 50°. The crude product which was thus-obtained was distilled at 0.3 Torr (112°-115°). There was obtained benzyl-(R)-2-hydroxyisocaproate; [α]D25 = + 18.0° (c = 1 in methanol); nD23 = 1.498.

Provenance & Evidence