6679added aqueous sodium hydroxide (4 mL, 1 N). The resulting mixture was heated for 5 h at 60 "C. After extraction with dichloromethane the ester 44 (1 16 mg, 92%) was isolated: IR 1740; IH NMR 7.38 (m, 5 H), 6.27 (m. 1 H). 6.07 (m, I H), 4.88 (d, J = 8, 1 H), 3.77 (m, 2 H), 3.10 (br s, 1 H), 2.77 (d, J = 8, I H), 1.17 (d, J = 7, 3 H, CH,), 1.07 (s, 3 Hydrolysis of Ester 44. A solution of ester 44 (35 mg, 0.089 mmol) in methanol (1.5 mL) and aqueous sodium hydroxide (2.5 mL, 1.5 N) was stirred at 80 "C for 2 days. After dilution with water the resulting mixture was extracted with dichloromethane. After evaporation of the organic layer, the residue was purified by preparative TLC and afforded amino alcohol 6 ( I 2.9 mg, 56%). [:Ip = -52" (c = 1.29).The alkaline aqueous layer was acidified with hydrochloric acid (10%) and extracted with dichloromethane. The residue was purified by prep arative TLC (ethyl acetate-heptane 70:30) and afforded the acid 45 (7 mg, 52%): [ a ] D = +134" (c = 0.7 in CHCI,); [a]D = + I 19" (c = 0.56 in 95% EtOH) Treatment of Oxazolines 24 and 28 with Benzyl Chloroformate. Preparation of Esters Carbamates 46 and 47. To a stirred solution (2 M) of oxazoline and sodium bicarbonate (2.2 equiv) in a mixture of dichloromethane-water (5050) and benzyl chloroformate ( I .