The 2-diazo-1, 3-diketones 1 react with thioamides 4 via the acyl ketenes 3, resulting from Wolff rearrangement, to give the 1, 3-oxazine-4-ones 10; however, by increasing the electrophilicity of the diazo compounds or the nucleophilicity of the thioamides, the 5- acylthiazoles 9 are obtained. These are derived from the diketocarbene intermediates 2. The structure of 9g was confirmed by X-ray diffraction analysis.-The best preparative method ...
