Patent GB-1398096-A (GB)
Title: Substituted xanthone carboxylic acid compounds
IPC: A61P37/08
Filed: 1972-07-12
Abstract: 1398096 Xanthone carbozylic acids SYNTEX (USA) Inc 12 July 1972 [23 Aug 1971] 32531/72 Heading C2C The invention comprises compounds of the formula wherein one X is H and the other is in which n is 1 or 2 and R is lower alkyl or cycloalkyl; and pharmaceutically acceptable, non-toxic esters, amides and salts thereof. They may be obtained by (1) oxidizing a 5- or 7-(alkylthio or cycloalkylthio)-xanthone-2-carboxylic acid or an ester thereof with peracid, optionally followed by hydrolysis to give the corresponding 5- or 7-alkylsulphinyl- or cycloalkylsulphinyl - xanthone - 2 - carboxylic acids or the alkyl esters thereof; or (2) oxidizing a 5- or 7-(alkylthio- or cycloalkylthio)-xanthone- 2-carboxylic acid or an ester thereof with H 2 O 2 , optionally followed by hydrolysis to give the corresponding 5- or 7-alkylsulphonyl- or cycloalkylsulphonyl - xanthone - 2 - carboxylic acids or the alkyl esters thereof, or (3) optionally converting a product of steps (1) or (2) to its corresponding pharmaceutically acceptable, non-toxic ester, amide or salt. Examples are given for the preparation of these compounds. Compounds of the above formula are useful for inhibiting the effects of allergic reactions, also as smooth muscle relaxants and as vasodilators. The compositions containing these compounds optionally together with other pharmaceutical agents, e.g. antibiotics and hormonal agents, may be administered orally, topically, parenterally, or by inhalation and in the form of either solid, liquid or gaseous doses including tablets, suspensions and aerosols. The 5- or 7-(alkylthio- or cycloalkylthio)- xanthone-2-carboxylic acids or esters thereof may be obtained by a process which comprises (1) condensing an o- or p-(alkylthio or cycloalkylthio)phenol with a 1,3-dicarboalkoxy- or dicarbocycloalkoxy-4-halobenzene in the presence of Cu 2 O to give the corresponding 1,3- dicarboalkoxy or dicarbocycloalkoxy-4-(o- or p-alkylthio- or cycloalkylthio-phenyloxy)-benzene, base hydrolysing the latter to give the corresponding 1,3-dicarboxy-4-(o- or p-alkylthio- or cycloalkylthio-phenyloxy)-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 psubstituted phenol wherein the substituent is OH, (C 1 -C 5 )alkoxy or cycloalkoxy with a 1,3- dicarboalkoxy or dicarbocycloalkoxy-4-halobenzene in the presence of Cu 2 O 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 p-substituted 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 as in (2) with a 1,3-dimethyl- 4-halobenzene 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 psubstituted 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-(C 1 -C 5 )alkoxy or cycloalkoxy xanthone-2-carboxylic acid of steps (2) and (3) to the corresponding 5- or 7-hydroxy compound; and (5) converting any 5- or 7-hydroxy-xanthone-2-carboxylic acid of steps (2), (3) and (4) to its (C 1 -C 5 )alkyl or cycloalkyl ester; and (6) treating a 5- or 7-hydroxy-xanthone-2-carboxylic acid ester of step (5) with a dialkylthiocarbamyl chloride in the presence of a 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) treating a product of step (6) with an alkyl halide in the presence of base optionally followed by hydrolysis to give the required compounds.