Synthesis of new pyrazolo[4,3-c]quinolin-3-one derivatives and some oxazolo[4,5-c]quinoline-2,4-diones

The new pyrazolo[4,3-c]quinolin-3-one derivatives 3a-c and 6a-c were prepared by the following three steps: first the preparation of ethyl 4-hydroxyquinoline-3-carboxylate derivatives 1 and 4 by reaction of isatoic anhydrides and ethyl malonate and ethyl acetoacetate respectively, then chloration of 1 and 4 with phosphorus oxychloride to give 2 and 5 and finally the condensation of 2 and 5 with hydrazine and its derivatives. In addition, the successful synthesis of oxazolo[4,5-c]quinoline-2,4-diones 9a-f are reported.