1-Azaxanthone-3-carboxylic acids and their production

Abstract

Novel 1-azaxanthone-3-carboxylic acid derivatives, which are shown by the following formula (I) ##STR1## wherein R is hydrogen, alkyl, alkoxy or halogen; R.sub.1 and R.sub.2 are the same or different and each is hydrogen, alkyl or alkenyl; and m is 1 or 2; and their physiologically acceptable salts, are usable as effective medicines for preventing and/or treating allergic diseases. The compound of the formula (I) can be produced by reacting a compound of the formula: ##STR2## wherein R and m have the same meaning as defined above; R.sub.3 is carboxyl or group which is convertible into carboxyl through hydrolysis; X is alkyl phosphate radical or halogen, with a compound of the formula: ##STR3## wherein R.sub.1 and R.sub.2 have the same meaning as defined above, or its salt, and conducting hydrolysis, if necessary.

Dependencies are inferred from the claim text.