IL37839A - Pharmaceutical compositions containing 4-hydroxy-3-cinnoline carboxylic acid derivatives,some new compounds of this type and their preparation - Google Patents

Description

PHARMACEUTICAL COMPOSITIONS CONTAINOtt 4-HYDROXY-3-CINNOLINE CARBOXYLIG ACID DERIVATIVES, SOME NEW , COMPOUNDS OF THIS TYPE . AND THEIR PREPARATION nsainn nn!nn O' OOTJ mnpii «ΤΒ Π This invention relates to pharmaceutical compositions and more particularly it relates to pharmaceutical compositions containing cinnoline derivatives which are active as inhibitors of the effects, following the combination of reagin-like antibodies and their antigens. They are therefore useful for the treatment of asthma, for example allergic asthma, and they may also be useful for the treatment of other syndromes or diseases initiated by an antigen-antibody reaction, for example hay fever, urticaria and auto-immune diseases.

According to the invention there are provided pharmaceutical compositions comprising a compound of the formula :- wherein R stands for a hydroxy, C-L_g alkoxy, C^_g alkoxyalkoxy , °7-10 phenylalkoxy or phenoxy radical; and the benzene ring A may optionally bear one to four substituents selected from C^_-^0 alkyl, cycloalkyl, C1_^ alkoxy, C^_1Q phenylalkyl and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from alkyl an( ^1-3 alkoxy radicals and nitro groups and halogen atoms; or a pharmaceutically-acceptable salt thereof; and an inert pharmaceutically-acceptable diluent or carrier.

It is to be understood that the compounds of the formula I can exist in the tautomeric cinnolone form having the general formula:- 0 H but for convenience they will all be referred to as 4-hydroxy-cinnoline derivatives in this specification.

As a suitable value for R1 there may be mentioned, for example, a hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, 2-ethoxyethoxy , benzyloxy or phenoxy radical.

As stated above, the benzene ring A may optionally bear one to four substituents, and according to one preferred embodiment of the invention it optionally bears one or two substituents. The substituent or substituents which may optionally be present in the benzene ring A may be selected from, for example, methyl, ethyl, n-propyl, n-butyl, isobutyl, t-butyl, n-hexyl, n-octyl, cyciohexyl, methoxy, ethoxy, n-propoxy, n-butoxy, benzyl, phenoxy, phenyl, tolyl, dimethylphenyl , trimethylphenyl, methoxyphenyl, chlorophenyl, bromophenyl, fluorophenyl, dichlorophenyl, dibromophenyl, chloro (methyl)phenyl and nitrophenyl radicals and chlorine, bromine and fluorine atoms By way of example, specific known compounds which are useful as active ingredients in the pharmaceutical compositions of the invention are as follows :- OH Suitable salts for use as active ingredients in the pharmaceutical compositions of the invention are, in the case where the compounds of the formula I are sufficiently basic, pharmaceutically-acceptable acid-addition salts derived from inorganic or organic acids; examples are hydrochlorides, hydrobromides , tartrates or citrates. Suitable salts in the case where the said compounds of the formula I are sufficiently acidic are salts in which the anionic part is derived from the said compound of the formula I and the cationic part is pharmaceutically-acceptable, for example ammonium salts, alkali metal salts, alkaline earth metal salts, aluminium salts or salts with pharmaceutically-acceptable organic bases, for example piperidine, triethanolamine or ethylenediamine.

Compounds which are particularly preferred, because of their particularly high activity, for use as active ingredients in the pharmaceutical compositions of the invention are 1l-hydroxy-6-phenylcinnol-3-yl carboxylic acid, ethyl 6-ethyl-4-hydroxycinnol-3-yl carboxylate and 4-hydroxy-6-n-propyl-cinnol-3-yl carboxylic acid, and pharmaceutically-acceptable salts thereof.

The activity of the compounds of the formula I, wherein R"*" and A have the meanings stated above, and the pharmaceutically-acceptable salts thereof, is demonstrated by their ability to inhibit, in the rat, passive cutaneous anaphylaxis induced by reaginic antibodies to egg albumin using BY pertussis as an adjuvant.

The pharmaceutical compositions of the invention comprise conventional diluents or carriers, and they can be obtained by well known methods.

The pharmaceutical compositions of the invention may be in a form suitable for administration by inhalation.

Suitable compositions comprise a mixture of the active ingredient with a solid diluent or carrier, for example, lactose, the said mixture being in fine particulate form suitable for administration from a powder inhalation device. Alternatively, the compositions may be administered by inhalation in the form of a suspension or solution in a suitable liquid, for example water or an aqueous or non-aqueous medium, using a conventional nebulizer or a pressurised container.

Alternatively, the pharmaceutical compositions of the invention may be in an intravenously-administrable form, for example a sterile injectable solution, or in an orally-administrable form, for example a solution, suspension, emulsion or syrup, or an .orally-administrable unit dosage form, for example a tablet or capsule.

The pharmaceutical compositions of the invention may also contain, in addition to a compound of the formula I or a pharmaceutically-acceptable salt thereof, one or more known active ingredients selected from β-adrenergic stimulants, for example isoprenaline, adrenaline, orciprenaline or isoethacine, and pharmaceutically-acceptable acid-addition salts thereof, for example a sulphate, and prostaglandins having broncho-dilatory activity, for example prostaglandin or Έ^» and phosphodiesterase inhibitors selected from the following compounds :- (a) 3-acetamido-6-methyl~8-n-propyl-s-triazolo [4 , 3-a]pyrazine ; (b) 2-amino-4,6-di-C-L_2j-alky1-5-0x0-4 ,5-dihydro-s-triazolo- [l,5-a]pyrimidines , for example 2-amino-6-methyl-5-oxo-4-n-propyl-4,5-dihydro-s-triazolo [l,5-a]pyrimidine ; (c) theophylline and related 3,5-di-C.^-alkylxanthines ; and (d) 6,8-di-C1_i(-alkyl-596-dihydro-5-ox0-s-triazolo [4,3-c]-pyrimidines, for example 5» 6-dihydro-5-oxo- ,8-di-n-propyl-s-triazolo [4 , 3-c jpyrimidine .

The pharmaceutical compositions of this invention may contain from 1% to 50% by weight of a compound of the formula I or a pharmaceutically-acceptable salt thereof. The orally-administrable unit dosage forms may contain 5 to 250mg. of a compound of the formula I or a pharmaceutically-acceptable salt thereof. When the compositions of the invention are used to treat asthma in man orally or by inhalation, a typical dose of the active ingredient of the formula I is from O.Olmg. to lmg./kg. at suitable intervals, for example at' 6-hourly intervals during the day. When the said compositions are used intravenously to treat asthma in man, a typical total daily dose is 25mg„ per man. When the said compositions are used, either by inhalation, orally or intravenously, to treat other syndromes or diseases initiated by an antigen-antibody reaction, a typical total daily dose is from 1 to lOOmg. per man.

The great majority of the compounds of the formula I are new compounds. According to a further feature of the invention, therefore, there are provided compounds of the formula I wherein A and R1 have the meanings stated above, and pharmaceutically-acceptable salts thereof, but excluding the following known compounds :- Substituent* at position R 6 7 8 H - - - - H - F - - H - - P - H - - - F H CI - - - H - CI - - H - - CI - H - - - CI H - Br - - * A dash indicates that there is a hydrogen atom at the position, It is to be understood that for convenience the new compounds of this invention will be referred to generically by the formula :- OH wherein D and R have the same meanings as A and R respectively, but it is to be understood that this definition does not include the known compounds which are listed above.

Suitable salts of the invention are those specifically mentioned hereinbefore.

One embodiment of the new compounds of the invention consists of compounds of the formula I, wherein R"*" stands for a C^g alkoxy, C^.g alkoxyalkoxy, cy_ o P^enylalkoxy or phenoxy radical, and the benzene ring A may optionally bear one to four substituents selected from C-^-^Q alkyl, cycloalkyl, alkoxy, C^^Q phenylalkyl and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from C_-> al yl and C -3 alko v radicals and nitro groups and halogen atoms, and pharmaceutically acceptable salts thereof, but excluding the five known esters listed above.

Another embodiment of the new compounds of the invention consists of pharmaceutically-acceptable salts of compounds of the formula I, wherein A and R^ have the meanings" stated above.

Another embodiment of the new compounds of the invention, and these compounds constitute a preferred group because generally speaking they are of high activity, consists of compounds of the formula I, wherein R1 stands for a hydroxy or alkoxy radical, and the benzene ring bears one to four C-L_^ alkyl radical or radicals only, and pharmaceutically-acceptable salts thereof, but excluding 4-hydroxy-6-methyl-cinnol-3-yl carboxylic acid and iJ-hydroxy-8-methylcinnol-3-yl carboxylic acid. A particularly preferred group of these compounds are those wherein there is an alkyl substituent at position 6 only.

Another embodiment of the new compounds of the invention, and these compounds constitute another preferred group because generally speaking they are of high activity, consists of compounds of the formula I, wherein R1 stands for a hydroxy or C-]__g alkoxy radical, and the benzene ring A is substituted with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and C-^-j alkox radicals and nitro groups and halogen atoms, and wherein the benzene ring A may in addition optionally bear one to three substituents selected from C]__rj alkyl, cycloalkyl and C1_<^ alkoxy radicals and halogen atoms, and pharmaceutically-acceptable salts thereof.

Of the last-named phenyl derivatives, those wherein the phenyl substituent is linked to position 6 of the nucleus are particularly preferred because of their particularly high activity. Accordingly there are provided compounds of the formula I, wherein R1 stands for a hydroxy or alkoxy radical, and the benzene ring A is substituted, in the 6-position only, with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and C-L_-j alkoxy radicals and nitro groups and halogen atoms, and pharmaceutically-acceptable salts thereof.

There are also provided compounds of the formula I, wherein **" stands for a hydroxy or alkoxy radical, and the benzene ring A is substituted in the 6-position with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and C^..^ alkoxy radicals and nitro groups and halogen atoms, and wherein the benzene ring A in addition bears one to three substituents selected from C-, c alkyl, cycloalkyl and alkoxy radicals and halogen atoms, and pharmaceutically-acceptable salts thereof.

As indicated above, particularly preferred new compounds of the invention are il-hydroxy-6-phenylcinnol-3-yl carboxylic acid, ethyl 6-ethyl-iJ-hydroxycinnol-3-yl carboxylate and 4-hydroxy-6-n-propylcinnol-3-yl carboxylic acid, and pharmaceutically-acceptable salts thereof.

According to a further feature of the invention there is provided a process for the manufacture of the compounds of 2 the formula IV wherein R stands for a hydroxy radical, and pharmaceutically-acceptable salts thereof, which comprises ring closing a compound of the formula:- wherein D has the meaning stated above and X stands for a chlorine or bromine atom, by means of a Friedel-Crafts catalyst and then, if desired, converting the carboxylic acid so obtained into a pharmaceutically-acceptable salt thereof.

The Friedel-Crafts catalyst may be, for example, titanium tetrachloride, aluminium chloride, stannic chloride, ferric chloride or antimony pentachloride. The reaction is conveniently carried out in an organic solvent, for example ethylene dichloride, tetrachloroethane, nitrobenzene or chlorobenzene, and it may be carried out at a temperature of 50-130°C.

It will be appreciated by those skilled in the art that, in the case where the benzene ring D bears a single m-substituent, this ring-closure process may give a mixture of the corresponding 5- and 7-substituted cinnoline derivatives. Such a mixture may be separated by physical methods.

The starting materials of the formula V are obtainable by the following generally known reactions :- V According to a further feature of the invention there is provided a process for the manufacture of the esters of the formula IV, and pharmaceutically-acceptable salts thereof, which comprises carrying out a generally-known esterification - IH - process using as starting material a carboxylic acid of the 2 formula IV, wherein R stands for a hydroxy radical, or an acid halide, acid anhydride, ester, nitrile or amide thereof.

Thus, for example, the said esters may be obtained by:-(1) Reacting the appropriate carboxylic acid with the appropriate alcohol (it is to be understood that "appropriate alcohol" hereinafter includes phenol) in the presence of a suitable catalyst. Such catalysts include, for example, inorganic acids, for example hydrogen chloride and polyphosphoric acid, and sulphuryl chloride and boron trifluoride, and organic acids, for example £-toluenesulphonic acid and sulphosalicylic acid, and other acidic reagents, for example, acidic ion-exchange resins, for example fZeo-Karb† 222 (H+ form) ('Zeo-Karb' is a Trade Mark). The reaction may be driven to completion by removal of the water formed, for example by absorption by a suitable drying agent, for example a suitable molecular sieve, or by distillation, for example by azeotropic distillation in the presence of a suitable organic solvent, for example benzene, in a suitable apparatus, for example a Dean and Stark apparatus. (2) Acylation of the appropriate alcohol by a suitable derivative of the appropriate carboxylic acid. By way of example there may be mentioned :- (a) reacting the appropriate acid halide, azide, or anhydride (obtainable in conventional manner from the carboxylic acid) with the appropriate alcohol; (b) reacting a mixed anhydride derived from the appropriate carboxylic acid, for example by treatment with tri luoroacetic anhydride, methanesulphonic anhydride, p_-toluenesulphonyl chloride or ethyl chloroformate , with the appropriate alcohol; and (c) reacting the appropriate carboxylic acid with a carbodiimide , for example dicyclohexylcarbodiimide , followed by treatment with the appropriate alcohol. (3) Alkylation of the appropriate acid or a suitable derivative thereof, by treatment with a suitable alkylating agent. By way of example there may be mentioned:- (a) reacting a salt of the appropriate carboxylic acid, for example an inorganic salt, for example the sodium or thallous salt, or an organic salt, for example the triethylamine salt, with a suitable alkylating agent, for example an alkyl halide, sulphate, sulphite or chlorosulphite , if desired in the presence of a suitable solvent, for. example dimethylformamide, dimethylacetamide or acetone; (b) reacting the appropriate carboxylic acid with an appropriate unsaturated compound, for example an olefin, for example isobutene, in the presence of a Lewis acid, for example sulphuric acid or boron trifluoride; and (c) reacting the appropriate carboxylic acid with an appropriate diazoalkane, for example diazomethane, or a triazene such as l-methyl-3-p-tolyltriazene.

( ) Trans-esterification and related reactions; these may be divided into two groups :- (a) Wherein an ester of the appropriate carboxylic acid with an alcohol or phenol, for example the methyl ester, is caused to react with a second alcohol or phenol, for example benzyl alcohol, to produce an ester of the appropriate carboxylic acid with the second alcohol or phenol. The reaction may be catalysed by an acid, for example p_-toluene-sulphonic acid, or by a base, for example the sodium derivative of the second alcohol or phenol. The reaction may be driven to completion by removal of the first alcohol, for example by distillation or by selective absorption by a suitable molecular sieve, or by the use of a large excess of the second alcohol, or both. (b) Wherein the appropriate carboxylic acid is reacted with an appropriate ester of another acid, for example triethyl orthoformate , or with an appropriate acetal, for example dimethylformamide diethyl acetal.

The said esters may also be obtained from the corresponding nitriles and amides by treatment with the appropriate alcohol in the presence of a suitable catalyst, for example p_-toluenesulphonic acid.

The pharmaceutically-acceptable salts of the compounds of the formula IV, which constitute one embodiment of the invention, are obtainable by conventional procedures.

The invention is illustrated by the following Examples Example 1 Titanium tetrachloride (2ml-.) was added to mesoxalyl chloride p_-ethylphenylhydrazone (2g-. ) in ethylene dichloride (50ml-.) and the mixture was heated under reflux for 18 hours.

The mixture was cooled and the solvent was removed under reduced pressure. The residue was extracted twice with hot 2N-sodium hydroxide solution (75ml. each time). The solution was treated with decolourising charcoal, filtered, and acidified with 10N-hydrochloric acid to pH 1; a cream coloured solid precipitated. This was filtered off and crystallised from isopropanol, with carbon treatment, to give 6-ethyl-ii-hydroxycinnolin-3-yl carboxylic acid as pale yellow plates, m.p.252-254°C. (decomposition).

The mesoxalyl chloride p_-ethylphenylhydrazone used as starting material was obtained as follows :- p_-Ethylaniline (24.2g-.) was added to concentrated hydrochloric acid (50ml-.) in water (100ml-.). The mixture was stirred and cooled with ice while an ice-cold solution of sodium nitrite (l4.1g-. ) in water (35ml-.) was added at a rate such that the internal temperature remained below 10°C. The resulting mixture was filtered and the filtrate was added dropwise to a stirred, cooled mixture of sodium acetate (37.6g-.), diethyl malonate (32ml-.), ethanol (400ml-. ) and water (60ml-. ). The rate of addition was controlled so that the temperature remained below 0°C. The resulting mixture was stirred for 2 hours at 0°C., and then for a further 3 hours whilst it slowly warmed up to room temperature. The solution was diluted with water (750ml-.) and extracted with chloroform (3 x 200ml-.). The chloroform extract was washed with water (2 x 100ml-. ) , dried over anhydrous magnesium sulphate, filtered, and the chloroform removed by evaporation under reduced pressure. The red oil thus obtained was fractionally distilled under reduced pressure to give diethyl mesoxalate p_-ethylphenylhydrazone as a yellow oil, b.p. l62-l64°C. at 0.1mm.

To a solution of the above diester (18. g-.) in boiling ethanol (32ml-.), 2N-sodium hydroxide solution (32ml-.) was added dropwise over 15 minutes. The solution was cooled and acidified to pH 1 by the addition of concentrated hydrochloric acid, the temperature being maintained below 30°C. by addition of ice. The resulting precipitate was filtered off, washed with water, and crystallised from ethanol to give long yellow needles of. ethyl hydrogen mesoxalate p_-ethylphenylhydrazone, m.p.l20°C. , The above acid ester (10.4g-.) was dissolved in ethanol (60ml-.), and 2N-sodium hydroxide solution (64ml-.) was added. The mixture was stirred at 50-55 °C. for 20 minutes. The solution was cooled, diluted with water (100ml-.), and acidified to pH 1 with concentrated hydrochloric acid while maintaining the temperature below 10°C. by the addition of ice. The resulting precipitate was filtered off immediately. It was then mixed with water (500ml-.), the mixture stirred for 10 minutes, and then filtered.

The solid residue was crystallised from benzene, with carbon treatment, to give mesoxalic acid p_-ethylphenylhydrazone, m.p.l 2°C. (decomposition).

Phosphorus pentachloride (40g-. ) was added to a stirred suspension of the above di-acid (18.9g'.) in petroleum ether (b.p.100-120°C. ; 100ml-.). After the initial vigorous reaction had subsided, the mixture was heated under reflux on a steam bath for 2 hours, and then filtered while still hot. The filtrate was cooled, and the resulting precipitated solid was filtered off and washed with petroleum ether (b .p .2iO-60°C-. ) to give mesoxalyl chloride p_-ethylphenylhydrazone as a yellow powder, m.p.122-123°C. (decomposition).

Example 2 A mixture of mesoxalyl chloride p_-phenylphenylhydrazone (12.0g-. ), titanium tetrachloride (4.8ml'.) and nitrobenzene (70ml-.) was heated on a steam bath for 2 hours. After cooling it was poured into 3N-sodium hydroxide solution (125ml-.). The suspension was stirred for 30 minutes and then filtered. The residue was suspended in 2N-Na0H (60ml-. ), stirred for 15 minutes, and again filtered. The combined filtrates were washed with ether (2 x 100ml-.). The aqueous layer was stirred for 1 hour with activated charcoal (2g-. ), and then filtered. The filtrate was heated to 80°C. and acidified with concentrated hydrochloric acid until the pH was 1. The resulting yellow precipitate was filtered off, washed with water, and crystallised from a mixture of dimethylformam de (80ml-. ) and water (80ml-.) to give 4-hydroxy-6-phenylcinnolin-3-yl carboxylic acid as a pale yellow powder, m.p.278-279°C. (decomposition).

The phenylhydrazone used as starting material was obtained as follows :- A solution of potassium hydroxide (4y.5g'. ) in ethanol (200ml-.) was added to a stirred suspension of diethyl mesoxalate p_-phenylphenylhydrazone (90g-. ) in ethanol (300ml-.). After stirring at room temperature for 15 minutes, water (250ml-.) was added and the mixture stirred for 2 hours. The solution was diluted with water (750ml-.), washed with methylene dichloride (3 x 250ml'.) to remove tars, and the aqueous layer was filtered and acidified by addition of concentrated hydrochloric acid until the pH was below 1. The resulting thick yellow suspension was stirred for 15 minutes, then filtered, and the residue washed with water. The yellow solid was re-suspended in water (200ml-.) and ethanol (20ml-.). Concentrated aqueous ammonia (d= 0.880; 10ml-.) was added and the suspension stirred for \ hour. Activated charcoal (lg-. ) was added, the suspension stirred for 15 minutes, and then filtered. The filtrate was cooled in ice and acidified with concentrated hydrochloric acid until the pH was below 1, to give a bright yellow precipitate. This was filtered off, washed with water, and dried to give mesoxalic acid p-phenylphenyl-hydrazone, m. .198-199 °C. after decomposing slowly from 170°C.

A mixture of mesoxalic acid p_-phenylphenylhydrazone (5.1g'.)» phosphorus pentachloride (8.5g'. ) and benzene (50ml-.) was heated under reflux on a steam bath for 45 minutes. The dark solution was diluted with petroleum ether (b .p.40-6O°C-. ) , then cooled, and the resulting orange solid filtered off and washed with petroleum ether (b .p .40-60°C-. ) to give mesoxalyl chloride p_-phenylphenylhydrazone , m.p.157-158°C. (decomposition). 'Example' 3 Dry hydrogen chloride was bubbled through a suspension of 4-hydroxy-6-phenylcinnolin-3-yl carboxylic acid (0.60g-. ) in boiling dry ethanol (25ml-.). Within 20 minutes a clear red solution had formed. This was heated for a further four hours, and then cooled and poured into water (100ml-.) containing potassium acetate (25g'. ). The suspension was filtered, and the residue washed with water and crystallised from k % aqueous ethanol (50ml-.) to give white crystals of ethyl 4-hydroxy-6-phenylcinnolin-3-yl carboxylate, m.p.257-259°C. (decomposition). Example Titanium tetrachloride (1.69ml-.) was added to mesoxalyl chloride p_-n-propylphenylhydrazone (2.0g-. ) in nitrobenzene (20ml-. ).· The mixture was heated on a steam bath for 6 hours, and then cooled and diluted with ether (100ml-.). Water (100ml-.) was added, and the mixture was stirred and basified with 5N-aqueous potassium hydroxide solution. The mixture was filtered, and the aqueous layer was separated and washed with ether (2 x 50ml'.). The aqueous layer was then heated to 80°C. and acidified with concentrated hydrochloric acid, to precipitate a white solid which, after cooling, was filtered off and washed with water. It was crystallised from ethanol to give 4-hydroxy 6-n-propylcinnolin-3-yl carboxylic acid, m.p.257°C. (decomposition) .

The following compounds were prepared in a similar manner:- In cases where the phenylhydrazone used as starting material bears a single m-substituent , two isomeric products are possible :- In the above manner the following mixtures of 5- and 7 substituted compounds were prepared:- The new starting materials used in the preparation of the above compounds were obtained as follows :- p_-n-Propylaniline (13.9g.) in a mixture of concentrated hydrochloric acid (21.6ml-.) and water (51.5ml-.) was diazotised by dropwise addition of a solution of sodium nitrite (7.25g-. ) in water (25ml'.), the temperature being maintained between -5°C. and 5°C. by external cooling. The solution was filtered and added dropwise to a stirred mixture of diethyl malonate (16.5ml-. ) , potassium acetate (22.8g-. ), ethanol (130ml-.) and water (26ml-.), the temperature being maintained at 0-5 °C. by external cooling. The mixture was stirred for 5 hours, during which its temperature rose to 20°C, and the mixture was then extracted with methylene dichloride (5 x 50ml-.). The combined extracts were washed with water, dried (MgSO'^), filtered and evaporated to give crude diethyl mesoxalate p_-n-propylphenylhydrazone as a viscous orange oil.

In a similar manner the following compounds were obtaine from the appropriate anilines :- 5N-aqueous potassium hydroxide solution (120ml-.) was added to diethyl mesoxalate 2 ,5-dimethylphenylhydrazone (50.4g-.) in ethanol (150ml'. ). Within a few minutes, the orange solution set to a yellow solid mass, which after standing at room temperature for 3 hours became a deep red solution. This was filtered, and the filtrate was acidified with concentrated hydrochloric acid to give a thick yellow precipitate. This was filtered off and washed with water to give mesoxalic acid 2,5-dimethylphenylhydrazone, m.p.171-173°C. (decomposition).

The following compounds were made in a similar way:- A solution of potassium hydroxide (1.4g-. ) in ethanol (20ml-.) was added to diethyl mesoxalate p_-t-butylphenylhydrazone (3.2g-. ) in ethanol (10ml-.). The mixture was left to stand for 5 minutes, in which time it set to a yellow solid mass. Water (40ml-. ) was added, and the mixture was stirred and warmed to 60°C. to give a clear red solution. This was cooled, acidified with concentrated hydrochloric acid, the yellow precipitate collected by filtration and crystallised from methanol to give mesoxalic acid p_-t-butylphenylhydrazone, m.p.222°C. (decomposition) .

The following compounds were made in a similar way:- A solution of potassium hydroxide (1.4g-. ) in ethanol (20ml-.) was added to diethyl mesoxalate p_-cyclohexylphenyl-hydrazone (3.il6g-. ) in ethanol (10ml-.). The mixture was stirred for 5 minutes, during which time a red solid precipitated. This was filtered off and washed successively with ethanol (5ml-.) and ether (3 x 10ml-.). The solid was added to a solution of potassium hydroxide (1.4g-. ) in ethanol (40ml-. ) and water (30ml-.), and the mixture was stirred at 60°C. for 30 minutes. Decolour-ising charcoal (lg-. ) was added, the solution stirred and cooled to room temperature, filtered, and the filtrate acidified with concentrated hydrochloric acid. The resulting yellow solid was filtered off and washed with water to give mesoxalic acid p-cyclohexylphenylhydrazone, m.p.203°C. (decomposition).

The following compounds were made in a similar way:- Over a period of 15 minutes, 2N-sodium hydroxide solution (62ml-.) was added dropwise to diethyl mesoxalate 2,3 dimethylphenylhydrazone (28.8g-.) in boiling ethanol (62ml-.).

More 2N-sodium hydroxide solution (124ml-.) was then added, and the solution was stirred and heated under reflux on the steam bath for a further 20 minutes. The resulting red solution was diluted with water (250ml-.), cooled in ice, and acidified with concentrated hydrochloric acid. The resulting yellow precipitate was filtered off and washed with water to give mesoxalic acid 2,3-dimethylphenylhydrazone, m.p.l64°C. (decomposition) .

Mesoxalic acid 2-ethylphenylhydrazone, m.p.134-136°C. (decomposition), was prepared in a similar manner.

Phosphorus pentachloride (12.0g-. ) was added to mesoxalic acid p_-n-butylphenylhydrazone (6„5g'. ) in cyclohexane (100ml-. ), and the mixture was heated under reflux on a steam bath for 1\ hours. The resulting dark solution was diluted with petroleum ether (b.p.40-60 °C. ; 100ml-.) and left to cool to room temperature. The precipitated yellow solid was filtered off and washed with petroleum ether (b .p.40-60°C-. ) to give mesoxalyl chloride p_-n-butylphenylhydrazone, m.p.115-117°C. (decomposition).

In a similar manner, the following compounds were prepared: - Example 5 Hydrogen chloride was bubbled through a suspension of 4-hydroxy-6-n-propylcinnolin-3~yl carboxylic acid (l.Og-.) in dry ethanol (30ml'.) which was stirred and heated under reflux on a steam bath. After 1 hour the solution was poured on to ice/ water (200g-. ) and the resulting white precipitate was filtered off and washed with water. It was crystallised from benzene to give ethyl 4-hydroxy-6-n-propylcinnolin-3-yl carboxylate, m.p.202°C.

The following esters were made in a similar manner from the appropriate starting materials :- Example 6 A mixture of 6-ethyl-4-hydroxycinnolin-3~yl carboxylic acid (2.0g-. ), methanol (50ml-.) and boron trifluoride etherate (4.0ml-.) was heated under reflux for 2 hours. The clear solution was cooled to room temperature, and a crystalline solid precipitated. This was filtered off and washed with cold methanol to give methyl 6-ethyl-iJ-hydroxycinnolin-3-yl carboxylate, m.p.233°C Methyl 6-n-butyl-il-hydroxycinnolin-3-yl carboxylate, m.p.l88°C. (crystallised from an acetone-cyclohexane mixture) was obtained in a similar manner.

Example 7 A mixture of 4-hydroxycinnolin-3-yl carboxylic acid (1.90g-. ), thionyl chloride (7.0ml-.) and dimethylformamide (0.5ml-.) was heated under reflux on a steam bath for 1 hour.

The excess thionyl .chloride was distilled off on a steam bath, the residue was cooled and mixed with n-butanol (10ml-. ). The resulting dark solution was heated under reflux on a steam bath for 1 hour, and then cooled and poured into water (100ml-.). The solution was neutralised by addition of saturated sodium bicarbonate solution. The resulting solid precipitate was filtered off, washed with water, and pressed as dry as possible on the filter. It was then washed with a small volume of ether to remove some brown oil. Crystallisation from benzene (with charcoal treatment) gave n-butyl ^-hydroxycinnolin-3-yl carboxylate, mop.l63-l650C.

Example 8 Titanium tetrachloride (l„9ml-. ) was added to a solution of mesoxalyl chloride o-phenylphenylhydrazone (2.5g-. ) in nitrobenzene (25ml-.). The mixture was heated on a steam bath for 6 hours, and then cooled and diluted with ether (100ml-.). The mixture was poured into potassium hydroxide solution (2N; 50ml'. ) j and the resulting mixture was stirred vigorously for a few minutes and then filtered. The aqueous layer was separated, washed with ether (2 x 50ml-. ) , stirred with charcoal (lg-. ) for 30 minutes, and filtered. The filtrate was then acidified to pH 1 with concentrated hydrochloric acid, causing the precipitation of a yellow-brown solid. This was filtered off, washed with water, and crystallised from aqueous dimethyl-formamide to give 4-hydroxy-8-phenylcinno.$¾-yl carboxylic acid, m.p.274°C. (decomposition).

In a similar manner the following compounds were obtained:- The new starting materials used in the preparation of the above compounds were obtained as follows :- Finely powdered 2-amino-4 ' -nitrobiphenyl (l6.9g-. ) was suspended in water (50ml-.). Concentrated hydrochloric acid (21ml'.) was added, followed by sufficient glacial acetic acid as co-solvent (about 150ml'. ) to re-dissolve most of the precipitated hydrochloride. The suspension was cooled to 0°C. and diazotised by the addition of sodium nitrite (7.0g-. ) in water (50ml-.). The clear solution was stirred for 10 minutes, filtered, and the filtrate added dropwise to a stirred mixture of diethyl malonate (l6ml-. ), potassium acetate (25g'« )» water (25ml-.) and ethanol (125ml-.), the temperature being maintained below 5°C. The resulting yellow suspension was stirred for one hour and then filtered, and the solid residue was washed with water to give diethyl mesoxalate 2- ( -nitrophenyl )phenyl-hydrazone, m.p.l06-108°C. .

The following compounds were made in a similar manner from the appropriate anilines, using the co-solvent stated :- m. p .

R (°C, Co-solvent decomposition) 4-Cl-2-0Me 85 None 2-Ph Oily solid Acetic acid 4-p_-tolyl 85 Dioxan 4- ( 2 , 5-dibromo- 89-91 Acetic acid phenyl) 4-p_- chloropheny1 81-82 Acetic acid 2,4-Pr!J Oil Acetic acid 4-m-tolyl-2-Me 4-56 Acetic acid 4-(4-chloro-3- 79-81 Acetic acid methylphenyl )- 2- e 4-(2,4,6-tri 88-90 None methylphenyl ) A solution of potassium hydroxide (16. g'.) in ethanol (100ml-. ) was added to a stirred suspension of diethyl mesoxalate 4-chloro-2-methoxyphenylhydrazone (43.6g-. ) in ethanol at 25°C. The mixture was stirred for 5 minutes, and the thick yellow precipitate was then filtered off and washed with ethanol (2 x 20ml-.). It was then stirred in ethanol (100ml-.) while a solution of potassium hydroxide (16. g-.) in water (100ml-.) was added dropwise. With continuous stirring the temperature was raised steadily to 70°C. over a period of 20 minutes, by which time a clear red solution was obtained. Charcoal (lg. ) was added, and the mixture was stirred for 5 minutes and then filtered. The filtrate was cooled and acidified to pH 1 with concentrated hydrochloric acid, the temperature being maintained below 10°C. b the intermittent addition of ice. The precipitate was filtered off, .washed with water, and dried to give mesoxalic acid 4-chloro-2-methoxyphenylhydrazone , m.p.2l8°C. (decomposition).

The following compounds were made in a similar manner from the appropriate starting materials :- m.p.

R (°c, decomposition) 2-Ph 215 2-p_-nitrophenyl 210-212 4-p_-chlorophenyl 244 4-p_-tolyl 186-189 4-(2,4,6-trimethyl- 163-165 pheny-1 ) 4- (2,5-dibromo- 158-161 phenyl) 2,4-Pr oil 4-m-tolyl-2-Me - 4-(4-chloro-3- - meth l henyl )-2-Me Phosphorus pentachloride (1.75g'« ) was added to a suspension of mesoxalic acid 4-chloro-2-methoxyphenylhydrazone (l.Og-. ) in cyclohexane (10ml-. ). The mixture was heated under reflux on a steam bath for 45 minutes, and then cooled and filtered. The residue was washed with petroleum ether (b.p.40-60°C. , 2 x 5ml;) to give mesoxalyl chloride 4-chloro-2-methoxyphenylhydrazone , m.p.166-168°C. (decomposition).

The following compounds were made in a similar manner from the appropriate starting materials :- m.p, R (°c, decomposition) 2-Ph 102-105 2-p_-nitrophenyl 168 4-p_-tolyl 145-147 4-(2,4,6-trimethyl- 119-121 phenyl) 4- ( 2 , 5-dibromophenyl ) 151-153 2,4-Pr oil 4-m-tol l-2-Me 121-123 4-(4-chloro-3-methyl- 170-171 phenyD-2-Me 4-£-chlorophen 1 151 Example 9 Sulphury1 chloride (0.3ml-.) was added dropwise to stirred suspension of 4-hydroxy-6-phenylcinnol-3-yl carboxylic acid (0.27g'. ) in dry methanol (20ml-.). The mixture was heated under reflux on a steam bath for 18 hours, and then cooled and filtered. The yellow solid residue was washed with methanol (5ml-.), and crystallised from 5 % v/v aqueous dimethyl-sulphoxide (40ml-. ) to give methyl yl carboxylate, m.p.256-257°C. (decomposition).

Example 10 2N-sodium hydroxide solution (6ml-.) was added dropwise to a stirred suspension of 4-hydroxy-6-n-propylcinnol-3-yl carboxylic acid (l.Og-.) in water (10ml-.). The solution was diluted with ethanol (50ml-.) to give a thick white gelatinous precipitate which was filtered off, washed successively with ethanol (10ml'.) and acetone (3 x 10ml-.) to give the disodium salt of i-hydroxy-e-n-propylcinnol^-yl carboxylic acid, m.p. above 320°C.

Example 11 Saturated aqueous calcium chloride solution (1.0ml-.) was added to a solution of the potassium salt of e-chloro-M-hydroxy-8-methoxycinnol-3_yl carboxylic acid (l.Og-.) in water (5ml-.), to produce a gelatinous white precipitate of the calcium salt of 6-chloro-4-hydroxy-8-methoxycinnol-3-yl carboxylic acid. The solid was separated in a centrifuge.

Example 12 Sulphur 1 chloride (0.25ml-.) was added dropwise to a suspension of 4-hydroxy-6-n-propylcinnol-3-yl carboxylic acid (0.32g. ) in 2-ethoxyethanol (10ml-.). The mixture was heated on a steam bath overnight, and then cooled and poured into water (100ml-.). The resulting white suspension was stirred and filtered. The solid residue was crystallised from 50$ v/v aqueous acetone (30ml-.) to give 2-ethoxyethyl -hydroxy-6-n-propylcinno¾n-3-yl carboxylate, m.p.246°C. (decomposition).

Example 13 A mixture of 4-hydroxy-6-phenylcinnolin-3-yl carboxylic acid (5g'« )> maize starch (65g'. ), calcium phosphate (130g-. ) and magnesium stearate (lg-. ) was compressed, and the compressed mixture was then broken down into granules by passage through a Ιβ-mesh screen. The resultant granules were then compressed into tablets each containing 50mg. of the active ingredient.

In a similar manner tablets were obtained containing 50mg. of the disodium salt of 4-hydroxy-6-n-propylcinnol^¾-yl carboxylic acid, or 50mg. of ethyl 6-ethyl-4-hydroxycinnolin-3-yl carboxylate.

Example 1 4-Hydroxy-6-phenylcinno$-3-yl carboxylic acid (20g.; screened through mesh size 90) and lactose (15g. ; screened through mesh size 90, British Standard 410:1962) were thoroughly mixed, and there was thus obtained a powder formulation suitable for inhalation for medicinal purposes.

The above procedure was repeated except that isoprenaline sulphate (O.lg.; screened through mesh size 90) was included as an additional active ingredient. There was thus obtained a powder formulation suitable for inhalation for medicinal purposes.

Example 15 An aerosol formulation was prepared consisting of finely divided disodium salt of 4-hydroxy-6-n-propylcinnc¾^-3-yl carboxylic acid, % w/w (screened through mesh size 90) and propellant to 100$ w/w (the propellant was a 60:H0 v/v mixture of dichloro-difluoromethane and l52-dichloro-l9l,2,2-tetra-fluoro ethane ) .

The above procedure was repeated except that isoprenaline sulphate 0.1% w/w (screened through mesh size 90) was included as an additional active ingredient. There was thus obtained an aerosol formulation suitable for medicinal purposes.

Claims (37)

What we claim is:-

1. A pharmaceutical composition comprising a compound of the formula:- wherein R1 stands for a hydroxy, C^_g alkoxy, C^__g alkoxyalkoxy , ^7-10 Phenyla^oxy or phenoxy radical; and the benzene ring A may optionally bear one to four substituents selected from Cl-10 alkyl» C5-7 cycloalkyl, alkoxy, c-7_10 Phenylalkyl and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from radicals and nitro groups and halogen atoms; or a phar aceutically-acceptable salt thereof; and an inert pharmaceutically-acceptable diluent or carrier.

2. A pharmaceutical composition comprising a compound of the formula I, wherein R stands for a hydroxy, C-j__g alkoxy, C7-10 Phenylalkoxy or phenoxy radical; and the benzene ring A may optionally bear one to four substituents selected from alkyl, alkoxy, cy_10 phenylalkyl, phenyl and phenoxy radicals and halogen atoms; or a pharmaceutically-acceptable salt thereof; and an inert pharmaceutically-acceptable diluent or carrier.

3. A composition as claimed in claim 2 wherein the benzene ring A bears one substituent only, selected from C^_^ alkyl, C-^f- alkoxy, C,-,_1Q phenylalkyl, phenyl and phenoxy radicals and halogen atoms.

4. A pharmaceutical composition comprising a compound of the formula I, wherein R1 stands for a hydroxy, alkoxy, (?7-10 phenylalkoxy or phenoxy radical; and the benzene ring A may optionally bear one to four substituents selected from ^1-10 a-^yl» ci_5 alkoxy> C ~io nen lal^yl and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from C]_-3 alkyl and radicals and halogen atoms; or a pharmaceutically-acceptable salt thereof; and an inert pharmaceutically-acceptable diluent or carrier.

5. A pharmaceutical composition comprising a compound of the formula I, wherein R1 stands for a hydroxy, C-^.g alkoxy, C7-10 Pnenyla k°xy or phenoxy radical; and the benzene ring A may optionally bear one to four substituents selected from Cl-10 alky1' C5-7 cydoa!ky!s Cl-$ alkoxy> C7-io Pheny^lky1 and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from alkoxy radicals and nitro groups and halogen atoms; or a pharmaceutically-acceptable salt thereof; and an inert pharmaceutically-acceptable diluent or carrier.

6. A composition as claimed in claim 1 wherein R stands for a hydroxy, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, 2-ethoxyethoxy, benzyloxy or phenoxy radical.

7. A composition as claimed in claim 1 or 6 wherein the benzene ring A bears one to four substituents selected from methyl, ethyl, n-propyl, n-butyl, isobutyl, t-butyl, n-hexyl, n-octyl, cyclohexyl, methoxy, ethoxy, n-propoxy, n-butoxy, benzyl phenoxy, phenyl, tolyl, dimethylphenyl , trimethylphenyl, methoxyphenyl, chlorophenyl, bromophenyl, fluorophenyl, dichlorophenyl, dibromophenyl, chloro (methyl )phenyl and nitro-phenyl radicals and chlorine, bromine and fluorine atoms.

8. A composition as claimed in claim 7 wherein the benzene ring A bears one or two substituents.

9. A composition as claimed in any of claims 1 to 8 in which the compound of the formula I is in the form of a pharmaceutically-acceptable acid-addition salt.

10. A composition as claimed in any of claims 1 to 8 in which the compound of the formula I is in the form of a salt in which the anionic part is derived from the said compound of the formula I and the cationic part is pharmaceutically-acceptable.

11. A composition as claimed in claim 10 in which the salt is an ammonium, alkali metal, alkaline earth metal or aluminium salt, or a salt with a pharmaceutically-acceptable organic base.

12. A composition as claimed in claim 5 in which the in active ingredient of the formula I is 4-hydroxy-6-phenylcinno^- _ 42, - 3-yl carboxylic acid, ethyl 6-ethyl-4-hydroxycinno¾?-3-yl carboxylate or 4-hydroxy-6-n-propylcinno¾?-3-yl carboxylic acid or a pharmaceutically-acceptable salt thereof.

13. A composition as claimed in any of claims 1 to 12 which is in a form suitable for administration by inhalation.

14. A composition as claimed in any of claims 1 to 12 which is in an intravenously-administrable form.

15. A composition as claimed in any of claims 1 to 12 which is in an orally-administrable form.

16. A composition as claimed in any of claims 1 to 15 which contains, in addition to a compound of the formula I or a pharmaceutically-acceptable salt thereof, one or more known active ingredients selected from 3-adrenergic stimulants, prostaglandins having bronchodilatory activity, and phosphodiesterase inhibitors selected from the following compounds:- (a) 3-acetamido-6-methyl-8-n-propyl-s-triazolo- [4,3-a]pyrazine, (b) 2-amino-4,6-di-C-L_|j-alkyl-5-oxo-4,5-dihydro-s-triazolo [l,5-a]pyrimidines , (c) theophylline and related 3,5-di-C1_i(-alkylxanthines , and (d) 6,8-di-C1_1|-alkyl-5 , 6-dihydro-5-oxo-s-triazolo [ , 3-c ]pyrimidines .

17. A composition as claimed in any of claims 1 to 16 which contains 1% to 505? by weight of the compound of the formula I or a pharmaceutically-acceptable salt thereof.

18. An orally-administrable unit dosage form as claimed in claim 15, which contains 5 to 250mg. of the compound of the formula I or a pharmaceutically-acceptable salt thereof.

19. A compound of the formula I, wherein A and R1 have the meanings stated in claim 1, or a pharmaceutically-acceptable salt thereof, but excluding the known compounds in table given dm pages 8 and 9 listed/ hereinbefore.

20. A compound as claimed in claim 19 wherein R"1" stands for a C_-S alkoxvs C3-6 alko yalkoxy » ^7-10 Phenylalkoxy or phenoxy radical, and the benzene ring A may optionally bear one to four substituents selected from alkyl, cycloalkyl, C -5 alkoxv» C7-io Pnenylalkyl and phenoxy radicals and halogen atoms and phenyl radicals which themselves may optionally bear one to three substituents selected from C, , alkyl and C. , alkoxy radicals and nitro groups and halogen atoms, or a pharmaceutically-acceptable salt thereof, but excluding the five known esters listed hereinbefore.

21. A pharmaceutically-acceptable salt of a compound of the formula I, wherein A and R1 have the meanings stated in claim 1 , but excluding the known compounds listed in table given on pages 8 and 9 hereinbefore.

22. A compound of the formula I, wherein R stands for a hydroxy or C^_g alkoxy radical, and the benzene ring A bears one to four alkyl radical or radicals only, or a pharmaceutically-acceptable salt thereof, but excluding 4-hydroxy-6-methylcinnoi?3-yl carboxylic acid and 4-hydroxy-8-methylcinnoi 3-yl carboxylic acid.

23. A compound as claimed in claim 22 wherein the benzene ring A bears a alkyl radical at the 6-position only, but excluding 4-hydroxy-6-methylcinno$-n5-yl carboxylic acid.

24. A compound of the formula I, wherein R^ stands for a hydroxy or Cj-6 alkoxy radical, and the benzene ring A is substituted with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and alkoxy radicals and nitro groups and halogen atoms, and wherein the benzene ring A may in addition optionally bear one to three substituents selected from alkyl, cycloalkyl and ^-5 alkoxy radicals and halogen atoms, or a pharmaceutically-acceptable salt thereof.

25. A compound as claimed in claim 24 wherein .^ stands for a hydroxy or alkoxy radical, and the benzene ring A is substituted, in the 6-position only, with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and alkoxy radicals and nitro groups and halogen atoms, or a pharmaceutically-acceptable salt thereof.

26. A compound as claimed in claim 2 wherein R"^ stands for a hydroxy or C-^.g alkoxy radical, and the benzene ring A is substituted in the 6-position with a phenyl radical which itself optionally bears one to three substituents selected from alkyl and alkoxy radicals and nitro groups and halogen atoms, and wherein the benzene ring A in addition bears one to three substituents selected from C, alkyl, C._ _ cycloalkyl 1-5 5-/ and C._p- alkoxy radicals and halogen atoms, or a pharmaceutically- acceptable salt thereof.

27. carboxylic acid or a pharmaceutically-acceptable salt thereof.

28. Ethyl 6-ethyl-4-hydroxycinno¾*-3-yl carboxylate or pharmaceutically-acceptable salt thereof.

29. ^i-Hydroxy-e-n-propylcinnof?3-yl carboxylic acid or pharmaceutically-acceptable salt thereof.

30. A process for the manufacture of a compound of the formula :- OH tands for a hydroxy radical, or a pharmaceutically-acceptable salt thereof, but excluding the known compounds which are listed in the table on pages 8 and 9 / hereinbefore, which comprises ring-closing a compound of the 1 formula:- wherein D has the meaning stated above and X stands for a chlorine or bromine atom, by means of a Priedel-Crafts catalyst, and then, if desired, converting the carboxylic acid so obtained into a pharmaceutically-acceptable salt thereof.

31. A process as claimed in claim 30 in which the catalyst is titanium tetrachloride, aluminium chloride, stannic chloride,. ferric chloride or antimony pentachloride .

32. A process as claimed in claim 30 or 31 which is carried out in ethylene dichloride, tetrachloroethane , nitrobenzene or chlorobenzene .

33. A process for the manufacture of an ester of the 2 formula IV wherein D has the meaning stated in claim 30 and R stands for a C^_g alkoxy, C^__g alkoxyalkoxy, phenylalkoxy or phenoxy radical, or a pharmaceutically-acceptable salt thereof, but excluding the known esters which are listed hereinbefore, which comprises carrying out a generally-known esterification process using as starting material a carboxylic 2 acid of the formula IV, wherein R stands for a hydroxy radical, or an acid halide, acid anhydride, ester, nitrile or amide thereof.

34. 3^. A pharmaceutical composition, claimed in claim 1, substantially as described in Example 13} l^ or 15.

35. A compound, claimed in claim 23 » substantially as described in Example 1.

36. . A compound, claimed in claim 19, substantially as described in any of Examples 2 to 7 .

37. A compound, claimed in claim 19, substantially as described in any of Examples 8 to 12. AGENTS FOR APPLICANTS PH.23206/24211 RA/JLL: 9 . 9 . 71 - k9 -