The new pyrazolo[4,3-c]quinolin-3-one derivatives 3a-c and 6a-c were prepar
ed by the following three steps: first the preparation of ethyl 4-hydroxyqu
inoline-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 conden
sation of 2 and 5 with hydrazine and its derivatives, In addition, the succ
essful synthesis of oxazolo[4,5-c]quinoline-2,4-diones 9a-f are reported.