Triethylamine → (4S-trans)-4,5-dihydro-5-[4-(methylsulfonyl)phenyl]-2-phenyl-4-oxazolecarboxylic acid ethyl ester

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Reaction Steps

(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).

Provenance & Evidence