Synthesis and transformations of derivatives of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acid

On the basis of methyl esters of 2-aryl-5-hydrazino-1,3-oxazole-4-carboxylic acids the earlier unknown methyl esters of 2-aryl-5-(3,5-dimethyl-1H-pyrazol-1-yl)-1,3-oxazole-4-carboxylic acids as well as their functional derivatives were synthesized. The latter were used for further transformations, in particular, for introducing the residues of highly basic aliphatic amines into the 5 position of oxazole, and the oxazol-2-yl moiety into the 4 position of the oxazole ring.