A facile synthesis of pyrazole, isoxazole and pyrimidine ortho-dicarboxylic acid derivatives via beta-enaminoketoesters

beta-Alkoxycarbonyl-beta-enaminoketoesters 1a,b react with hydrazines to give pyrazole ortho-dicarboxylic acid derivatives 3, 4 and 5. Similarly la reacts with hydroxylamine to give isoxazole 6 and with amidines and guanidine to give pyrimidine ortho-dicarboxylic acid monoesters 7a-c. The total or partial hydrolysis of selected heterocycles afforded the dicarboxylic acids 8, 9 and 10 and the dicarboxylic acid monoesters 11 and 12. (C) 1997 Elsevier Science Ltd.