Nitrile compounds carbonyl ylide generation

Another synthesis based on the combination of these fragments is the 1,3-dipolar cycloaddition of carbonyl compounds to nitrile ylides. The latter are generated by photolysis of 1-azirines when the irradiation is carried out in the presence of an acyl chloride and triethylamine, oxazoles are formed in moderate yields (equation 121). 

Huisgen and his co-workers190 have recently reported that the addition of aromatic nitrile ylides to carbonyl compounds results in the formation of A3-oxazolines, which are easily oxidizable to oxazoles. Typically, benzonitrile 4-nitrobenzylide (131, Ar = p-OsNC6H4), generated from the imidoyl chloride (130) by 1,3-elimination of hydrogen chloride with triethylamine, reacts smoothly with benzaldehyde to give a pair of... 

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