Synthesis of 5-chloro-4,5-diaryl-Δ3-1,3-oxazolin-2-ones

During an attempt at the synthesis of the oxazoles by the reactions of the oxazolines (I) with phosphorus pentachloride the authors obtained the 5-chloro-4,5-diaryl-Δ3-1,3-oxazolin-2-ones instead of the expected 4,5-diaryl-2-chlorooxazoles. As electrophiles, these compounds are active in nucleophilic addition and substitution reactions. Thus, in their reaction with methanol the 4,5-dimethoxy-4,5-diaryl-1,3-oxazolidin-2-ones are formed with quantitative yields. When heated they are easily converted into 5-methoxy-4,5-diaryl-Δ-1,3-oxazolin-2-ones. The compositions and structures were proved by IR and PMR spectroscopy and elemental analysis