Patent GB-1398097-A (GB)
Title: Substituted xanthone carboxylic acid compounds
IPC: A61P37/08
Filed: 1972-07-12
Abstract: 1398097 Substituted xanthone carboxylic acid compounds SYNTEX CORP 12 July 1972 [23 Aug 1971] 32532/72 Heading C2C The invention comprises compounds of the formula wherein R is H, C 1 -C 5  alkyl or C 3 -C 5  cycloalkyl, and esters, amides and salts thereof. They may be obtained by (1) condensing an o- or p-(alkylthio- or cycloalkylthio phenyl) with a 1,3-dicarboalkoxy- or dicarbocycloalkoxy-4- halobenzene in the presence of cuprous oxide to give the corresponding 1,3-dicarboalkoxy- or dicarbocycloalkoxy-4-(oorp-alkylthio orcycloalkylthiophenyloxy)-benzene, base hydrolysing the latter to give the corresponding 1,3- dicarboxy-4-(o- or p-alkylthio- or cycloalkylthiophenyloxy)-benzene, and cyclizing the latter to give the corresponding 5- or 7-(alkylthio or cycloalkylthio)-xanthone-2-carboxylic acid; or (2) condensing a o- or p-substituted phenol wherein the substituent is hydroxy, (lower) alkoxy or cycloalkoxy with a 1,3-dicarboalkoxy or dicarbocycloalkoxy-4-halobenzene in the presence of cuprous oxide to give the corresponding 1,3 - dicarboalkoxy or dicarbocycloalkoxy-4-(o- or p-substituted phenyloxy)- benzene, base hydrolysing the latter to give the corresponding 1,3-dicarboxy-4-(o- or psubstituted phenyloxy)-benzene, and cyclizing the latter to give the corresponding 5- or 7- substituted xanthone-2-carboxylic acid; or (3) condensing a o- or p-substituted phenol wherein the substituent is hydroxy (lower) alkoxy or cycloalkoxy with a 1,3-dimethyl-4- halobenzene in the presence of cuprous oxide to give the corresponding 1,3-dimethyl-4-(o- or p-substituted phenyloxy)-benzene, oxidizing the latter to give the corresponding 1,3-dicarboxy-4-(o- or p-substituted phenyloxy-benzene, and cyclizing the latter to give the corresponding 5- or 7-substituted xanthone-2-carboxylic acid; and (4) converting any 5- or 7- lower alkoxy xanthone-2-carboxylic acid of steps (2) and (3) to the corresponding 5- or 7- hydroxy compound; and (5) converting any 5- or 7-hydroxyxanthone-2-carboxylic acid of steps (2), (3) and (4) to its (lower)alkyl or cycloalkyl ester; and (6) treating a 5- or 7-hydroxyxanthone-2-carboxylic acid ester of step (5) with a dialkylthiocarbamoyl or dicycloalkylthiocarbamoyl chloride in the presence of base, rearranging the product thereof, and base hydrolysing the rearranged product thereof to give the corresponding 5- or 7-mercaptoxanthone-2-carboxylic acids; and (7) optionally treating a product of step (6) with an alkyl halide in the presence of base optionally followed by hydrolysis; and (8) optionally converting a product of steps (1) and (6) to its corresponding non-toxic esters, amides and salts. Examples are given for the production of these compounds. The above compounds are useful for inhibiting the effects of allergic reactions, also as smooth muscle relaxants or vasodilators. They may be administered, optionally in conjunction with other pharmaceutical agents, e.g. antibiotics and hormonal agents, orally, topically, parenterally, or by inhalation and in the form of either solid, liquid or gaseous doses including tablets, suspensions and aerosols.