Patent GB-942524-A (GB)
Title: Pharmaceutical compositions containing quinoline compounds
IPC: A61K31/00
Filed: 1962-02-08
Abstract: 6,7-Dimethoxy -4- quinolinol is obtained by reacting 4-aminoveratrole with diethyl ethoxy-methylenemalonate, the 3- carbethoxy -6,7-dimethoxy -4- quinolinol formed being saponified to the corresponding 3- carboxy derivative which is then decarboxylated to yield the desired product.  Similarly prepared are 6,7-diethoxy- 4-quinolinol, 6,8-dimethoxy -4-quinolinol, 7-methoxy -4- quinolinol and 7-methylthio -4- quinolinol starting from the appropriate alkoxy- or alkylthioaniline.  1,2-Diethoxy -4- aminobenzene is obtained by catalytic hydrogenation of the corresponding 4-nitro compound. 6-Methoxy -4- quinolinol is obtained by reacting p-anisidine hydrochloride with diethyl oxalacetate sodium salt, the ethyl 4-hydroxy -6-methoxy-quinoline -2- carboxylate formed being saponified and decarboxylated in successive steps. 6,7-Dimethoxycarbostyril is prepared by the self-condensation of 3,4-dimethoxy -6- amino-cinnamic acid, the latter being obtained by reducing the corresponding 6-nitro compound with hydrochloric acid and ferrous sulphate.  6,7-dimethoxyquinoline and 6,7-dimethoxylepidine are obtained by catalytic hydrogenation of their respective 2-chloro derivatives.  5,8-Dimethoxy -2- methyl -4- quinolinol is prepared by condensing 2,5-dimethoxyaniline with ethyl acetoacetate. Similarly prepared, from the appropriate dialkoxy-anilines, are 6,7-diethoxy -2- methyl -4- quinolinol and 6,7-dimethoxy -2- methyl -4- quinolinol.  Also, 6,7-dimethoxy -4- methyl -2- quinolinol is obtained by reacting 4-aminoveratrole with ethyl aecetoacetate.  6,7-Dimethoxy -3- quinolinol is obtained by diazotisation, and subsequent heating, of 6,7-dimethoxy-3-aminoquinoline which is prepared by the catalytic hydrogenation of the corresponding 3-nitro compound. 5,6,7-Trimethoxyquinaldine is obtained by reacting paraldehyde with 3,4,5-trimethoxyaniline, the latter being obtained by catalytic hydrogenation of the corresponding trimethoxynitrobenzene.  Several of the above quinoline compounds are obtained as, or converted to, their hydrochloride salts.  Also, 6,7-dimethoxy -4- quinolinol is reacted with methyl p-toluenesulphonate to yield 4-hydroxy-6,7-dimethoxy -1- methylquinolinium p-toluenesulphonate. The compounds are useful as hypotensive agents (see Division A5).ALSO:Hypotensive compositions comprise a pharmaceutical carrier and, as the added active ingredient, a quinoline derivative of formula <FORM:0942524/A5-A6/1> where n is 1, 2 or 3; R is a methoxy, ethoxy or methylmercapto group and, where n is greater than 1, the R's may be the same as or different from one another; each of R2 and R4 is a hydrogen atom, or a hydroxy or methyl group; R3 is a hydrogen atom or a hydroxy group; or a pharmaceutically acceptable salt of such a compound.  The compositions may be administered orally or parenterally in the form of tablets, elixirs, suspensions, capsules and solutions.  Acids suitable for forming salts of the active quinoline bases are, for example, hydrochloric, nitric, phosphoric, sulphuric, acetic, citric, malic and p-toluenesulphonic acids.  The preparation of specified active ingredients is described (see Division C2), the specified compounds being 6,7-dimethoxycarbostyril, 6,7-dimethoxy-4-quinolinol and its hydrochloride, 6,7-diethoxy-4-quinolinol and its hydrochloride, 6 -methoxy-4-quinolinol and its hydrochloride, 6,8-dimethoxy-4-quinolinol and its hydrochloride, 7-methoxy-4-quinolinol and its hydrochloride, 6,7-dimethoxyquinoline hydrochloride, 5,8-dimethoxy-2-methyl-4-quinolinol hydrochloride, 6,7-diethoxy-2-methyl-4-quinolinol and its hydrochloride, 6,7-dimethoxy-3-quinolinol hydrochloride, 6,7-dimethoxy-4-methyl-2-quinolinol, 7-methylthio-4 - quinolinol, 4 - hydroxy - 6,7 - dimethoxy - 1 - methylquinolinium p-toluenesulphonate, 5,6,7-trimethoxy - quinaldine hydrochloride, 6,7 - dimethoxylepidine hydrochloride hemihydrate and 6,7 - dimethoxy - 2 - methyl - 4 - quinolinol hydrochloride.