反应详情

(2S,3R)-Ethyl-2-amino-3-[4-(methylsulfonyl)phenyl]-3-hydroxy-propanoate (Compound VIc) (10 g, 0.0348 moles) is reacted at about 0° C. in a reaction vessel with benzenecarboximidic acid ethyl ester hydrochloride (Compound IV hydrochloride salt wherein R2 is phenyl and R4 is ethyl) (about 7.1 g, 0.03828 moles) in 1,2-dichloromethane (about 650 mL) containing triethylamine (3.9 g, 0.03828 moles). Thereafter, water is added (about 500 mL). Next, the organic layer is separated and washed with dilute hydrochloric acid (about 1 N) and dilute sodium bicarbonate (about 1N). The washed organic layer is dried over anhydrous sodium sulfate. The dried organic layer is heated to evaporate the 1,2-dichloromethane to yield (4S-trans)-4,5-dihydro-5-[4-(methylsulfonyl)phenyl]-2-phenyl-4-oxazolecarboxylic acid ethyl ester (Compound IIIk).

1. customNext, the organic layer is separated
2. washwashed with dilute hydrochloric acid (about 1 N) and dilute sodium bicarbonate (about 1N)
3. dry with materialThe washed organic layer is dried over anhydrous sodium sulfate
4. temperatureThe dried organic layer is heated
5. customto evaporate the 1,2-dichloromethane