Patent GB-1000892-A (GB)
Title: 1,8-naphthyridine-3-carboxylic acids and derivatives
IPC: C07D213/74
Filed: 1961-12-22
Abstract: The invention comprises 1-YZ-3-X-4-oxo-1,4 - dihydro - 1,8 - naphthyridines (optionally containing further nuclear substituents), where X represents -COOH or a salt thereof, or a C2- 11-alkoxycarbonyl, C2- 12-tertiary- or C1- 6-secondary - amino - C3- 7 - alkoxycarbonyl, cyano, carbamyl, aminocarbamyl, hydroxycarbamyl, acyloxycarbamyl, phenoxycarbonyl, hydrocarbonmercaptocarbonyl, -C(:NH)O-(C1- 6-alkyl),-C(:NH)NH2, -C(:NH)NH(C1- 6-alkyl), -CSOH or -CSSH group, Y represents a C1- 10 bivalent aliphatic hydrocarbon radical attached to the 1-nitrogen atom through a saturated carbon atom, and Z represents a hydrogen or halogen atom or a hydroxy, carboxyl, C2- 7-alkoxycarbonyl, cyano, carbamyl, C1- 8 aliphatic hydrocarbonoxy, (monocarboxylic - aryl) - (C1- 6- alkoxy), C1- 6-secondary - or C2- 12- tertiary - amino, C3- 8 -cycloalkyl or lower-aromatic radical or a second 3 - X - 4 - oxo - 1,4 - dihydro - 1,8 - naphthyridinyl-1 residue (" lower-aromatic " denoting radicals having one or two aromatic rings which may be benzenoid or 5- or 6-membered hetero-aromatic, especially a phenyl radical which may optionally carry 1-3 C1- 6-alkyl, -alkoxy, -alkylmercapto, -alkylsulphinyl or -alkylsulphonyl, halo, amino, mono- or di-(C1- 6 -alkyl)-amino, nitro, C1- 6-alkanoylamino, C6- 8 - carbocyclic - aroylamino, trihalomethyl, phenoxy, benzyloxy, benzoyl, C1- 6-alkanoyl, C1- 6-secondary-or C2- 12 - tertiary - amino - C2- 6-alkyl, -alkoxy or -alkylamino, hydroxy, cyano, aminomethyl, carbamyl, carboxy, C2- 6-alkoxy-carbonyl, phenylmercapto, benzyl or p-methoxyphenoxy substituents), and also the bisesters of such compounds wherein X is -COOH with C2- 10 aliphatic diols, and the preparation of the foregoing compounds by reacting a corresponding (1-unsubstituted) 3-X-4-hydroxy-1,8-naphthyridine with an organic ester of a strong acid providing the desired 1-substituent (e.g. a compound Z-Y-An or An-Y-An, where An is the anion of a strong inorganic acid or an organic sulphonic acid), and, if desired, converting a resulting 3-alkoxycarbonyl compound into the free acid or the free acid into a salt (including salts with organic bases) or ester (including thioesters and the aforesaid bis-esters) thereof. Preferred compounds are those of the general formula <FORM:1000892/C2/1> wherein Q represents a hydrogen atom or 1-4 substituents, in positions 2,5,6 or especially 7, independently selected from halogen atoms and C1- 6-alkyl, -alkoxy, -alkylmercapto, -alkyl-sulphinyl and -alkylsulphonyl, hydroxy, hydroxy-(C1- 6-alkyl), amino, mono- and di-(C1- 6-alkyl)-amino, hydrazino, nitro, C1- 6-alkanoylamino, C6- 8-carbocyclic-aroylamino, trihalomethyl, C1- 6 - alkanoyl, C1- 6 - alkanoyloxy -C1- 6-alkyl, C1- 6-secondary- and C2- 12-tertiaryamino-C2- 6-alkyl, -alkoxy and -alkylamino, monocarbocyclic - aryl, monocarbocyclic - aryloxy, -mercapto, -amino, -C1- 6-alkyl, -C2- 6-alkoxy, -C2- 6-alkenyl, -C2- 6-haloalkenyl and -C2- 6-alkynyl, monocarbocyclic-aroyl, cyano, amino - (C1- 6 - alkyl), (C1- 6 - alkanoylamino)-(C1- 6-alkyl), carbamyl, carboxyl and C2- 6-alkoxycarbonyl radicals. In the preparation of these preferred compounds, a 7-acrylamino compound may be hydrolysed to a 7-amino compound, which may be converted, via its diazonium salt, to a 7-hydroxy compound, which may be halogenated to form a 7-halo compound, or a 7-[2-(lower-aromatic)-ethenyl] compound may be reduced to a 7-[2-(lower-aromatic)-ethyl] compound or oxidized to a 7-carboxy compound.  Reference is also made to replacement of a 7-halo substituent by reaction with catalytically activated hydrogen (to replace it by hydrogen) or with a sodium alkoxide, a sodium alkylmercaptide, an alkylamine, a dialkylamine, hydrazine, a tertiary-or secondary-amino-alkylamine or a sodium tertiary- or secondary-amino-alkoxide, and to the conversion of basic compounds into acid addition salts, of tertiary bases into quaternary ammonium salts, of 3-carboxylic esters into amides, hydrazides, hydroxamic acids and their O-acyl derivatives, or higher esters (including aminoalkyl esters), and of a 3-carboxylic hydrazide into an amide by heating with Raney nickel in ethanol, to the removal of a 7-carboxyl group by pyrolysis, to the acylation of a 7-amino group, to the replacement of a 7-amino group by a bromine atom by the Sandmeyer reaction, to the conversion of a 1-(3-hydroxypropyl) group to a 1-(3-chloropropyl) group by the action of a chlorinating agent, and of a 3-carboxylic amide to a 3-nitrile by the action of benzenesulphonyl chloride and pyridine, to the hydrogenation of an unsaturated Y chain, to the hydrolysis of a 1-(2-vinyloxyethyl) group or hydrogenolysis of a 1-(2-benzyloxyethyl) group to a 1-(2-hydroxyethyl) group, to the esterification of a 7-hydroxymethyl group, and to the chlorination of a 7-styryl compound and dehydrochlorination of the product to a 7-phenylethynyl compound. Pharmaceutical compositions.-The various compounds described above possess anti-bacterial, sedative and barbiturate-potentiating properties, and may be administered in admixture with suitable pharmaceutical carriers.  Alkyl 4 - hydroxy - 1,8 - naphthyridine - 3-carboxylates are prepared by reacting a 2-amino-pyridine with a dialkyl ethoxymethylenemalonate to yield a dialkyl N-(2-pyridyl)-aminomethylenemalonate and cyclizing this by heating in a high boiling solvent.  The hydrolysis of some of these esters to the free acids is described.  For 7-acylamino derivatives the starting material is 2,6-diaminopyridine and an acid anhydride is included in the cyclizing step.  Ethyl 4 - hydroxy - 7 - tribromethyl - 1,8-naphthyridine - 3 - carboxylate is prepared by brominating the corresponding 7-methyl compound.  5,6-Dimethyl- and 6-ethyl-2-aminopyridine are prepared by the action of sodamide on 2,3-dimethyl- and 2-ethyl-pyridine respectively.  Specification 1,000,893 is referred to.