Verfahren zur Herstellung von neuen niederen Alkylestern von 6,7-Di-(niederalkoxy)-4-hydroxychinolin-3-carbonsäuren

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 where n is 1, 2 or 3; R is a methoxy, ethoxy or methylmercapto group and, wher