Unusual rearrangements of 2-aroylimidoyl-2-phenylethylidene to 2,5- disubstituted oxazoles

Article abstract of DOI:10.1016/S0040-4020(98)01171-5

Flash vacuum pyrolysis of 2-aroyl-3-phenylisoxazol-5(2H)-ones leads to good yields of 2-aryl-4-phenyloxazoles, and smaller quantities of 2-aryl-5- phenyloxazoles and 5-aryl-2-phenyloxazoles. The mechanism of formation of the 2,5-disubstituted products has been investigated by ¹³C and substituent labelling, and a non-statistical breakdown of a symmetrical intermediate is invoked to rationalise the product formation.