Urea → 3-[4-(4-Methoxyphenyl)-5-phenyl-1,3-oxazol-2-yl]propanoic acid

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Reaction Steps

A mixture of the crude 4-methoxybenzoin hemisuccinate (20.8 g, 0.061 mole) of Step B, urea (8.7 g, 0.146 mole) and acetic acid (60 mL) is heated at reflux under nitrogen for 5.5 hours. The mixture is cooled and poured into ice water. The liberated oil is extracted with ethyl acetate (3x). The extracts are washed with water until neutral and then extracted with saturated sodium carbonate. The combined aqueous extracts are carefully acidified in the cold with concentrated HCl and extracted with ethyl acetate. The organic extract is dried (MgSO4) and evaporated to dryness to provide a waxy yellow oil (19.6 g). Purification of the residue by flash chromatography (on silica Merck-60, eluant: dichloromethane-ethyl acetate 8:2) yields a pale yellow solid (14.3 g, 72.7%), m.p. 100°-101° C.

Provenance & Evidence