反应详情

2-Chloroethyl lactate (1.91 g, 12.5 mmol) and various amounts of isopropyl glycolate (1.48, 2.22 and 2.95 g; 12.5, 18.8 and 25.0 mmol, respectively) in 25 mL of ethyl ether containing 0.125% tert-butylbenzene were added to 1.75 g Lipase P30 powder and the reaction mixtures were agitated on an orbital shaker (175 RPM) at room temperature for 48 hr. After 48 hr, conversion of 2-chloroethyl lactate to the title compound was estimated (by GC, Method A) to be 30, 38 and 44% with 1.0, 1.5 and 2.0 equivalents of isopropyl glycolate, respectively. The GC peak assigned to the title compound was confirmed by HRMS: calcd for C7H10O5Tms (M--CH3) 247.1001, obsd 247.0990. A portion of one of the reactions was partially purified by flash chromatography (ethyl acetate/hexane, 20/80) to give a mixture of 2-chloroethyl lactate and the title compound. The partially purified mixture was separated by flash chromatography (CH2Cl2 /isopropanol, 99/1) to give the title compound: 1H NMR δ 1.27 (d, 6H, J=6.3 Hz), δ 1.49 (d, 3H, J=7.0 Hz), δ 3.28 (d, 1H, J=4.6 Hz), δ 4.42 (m, 1H), δ 4.60 (d, 1H, J=15.8 Hz),δ 4.71 (d, 1H, J=15.8 Hz), δ]5.09 (m, 1H, J=6.3 Hz); 13C NMR 20.3, 21.7, 61.5, 66.9, 69.6, 166.8, 174.9.

1. customthe reaction mixtures
2. waitAfter 48 hr