(5)-Hydroxy quinolopyranone (2)-carboxylic acid derivs. - prepd. by reacting (2,4)-dihydroxy (3)-acetyl quinoline with dialkyl or diaryl oxalate, used for asthma treatment

摘要

Novel quinolopyran-4-one-2-carboxylic acid deriv. are of formula (I):- (where X is 1-5C alkyl, 1-5C alkoxy, halogen, aryl-alkoxy of total 7-10C, alkoxycarbonyl of total 2-6C, or 6-10C aryl; n is 1-4, with the proviso of X's are same or different when n >=2). These cpds. are used for treating allergic asthma and they may inhibit the release of chemical agent from ast cell produced by antigen-antibody reaction. It has low toxicity e.g. LD50 = 150-560 mg, ED50 =0.5 mg, LD50/ED50 >=1000 in mice. It is prefd. by treating cpd. of formula (II) with cpd. of formula (ROOC)2 where R is 1-5C alkyl, phenyl or benzyl.