NO149503B - ANALOGY PROCEDURE FOR THE PREPARATION OF THERAPEUTIC ACTIVE SUBSTITUTED TETRAZOLES. - Google Patents

Description

The present invention relates to an analogue method for the preparation of therapeutically active substituted tetrazoles with the general formula

in which R denotes alkyl or alkoxy with 1 or 2 carbon atoms,

R 2 denotes alkyl or alkoxy with 1 or 2 carbon atoms, hydrogen, nitro or halogen, R 3 denotes hydrogen or alkyl with 1-4 carbon atoms, and n is 0, 1 or 2 and pharmaceutically acceptable salts thereof. Such salts can e.g. be salts with alkali metals, such as sodium, or with organic bases, such as dimethylaminoethanol. In formula I, the group R<1> is attached to a ring carbon atom.

In the formula, the circle in the tetrazole ring denotes a pair of double bonds which, together with the bonds shown, fulfill the valence requirements for the ring carbon atom and all valences as close as one for the four ring nitrogen atoms. The last nitrogen valence

3

is fulfilled by the group R .

In those of the compounds in question in which the tetrazole ring is unsubstituted, the hydrogen atom exists in tautomerically bound form

1 2

to either the N or N atom, i.e.

For simplicity, it is illustrated herein as if the hydrogen atom is bound to the N"*" atom. Such a tautomer i does not occur in compounds where the tetrazole ring is substituted with an alkyl group, as the group then sits in a single position. The compounds in question are useful in anti-allergic agents, as well as in treatment methods against allergies, in which a compound of formula I is administered in a mammalian organism as needed. Preferred compounds are those in which n = 0, i.e. that the 2-, 3- and 4-positions in the quinol part are unsubstituted, and where R 2 denotes hydrogen. Another preferred group of compounds are those in which one of the nitrogen atoms in the tetrazole ring is substituted with an alkyl group of 1-4 carbon atoms, preferably methyl. When alkyl or alkoxy substituents are present anywhere in the formula, they preferably contain a carbon atom. Compounds in which R 2 denotes chlorine, iodine, methyl or nitro constitute a preferred subgroup, as well as compounds in which R"<*>" denotes methyl.

The analog method according to the invention is characterized by the fact that 8-carboxyquinoline with the general formula

where R 1 , R 2 and n have the meanings given above, are activated and reacted with an aminotetrazole of the general formula

where R<3> has the meaning given above.

The compounds are thus produced by reacting a substituted 8-carboxyquinoline with, aminotetrazole or an alkylaminotetrazole. It is preferred to activate the 8-carboxy groups by methods such as. is used in peptide chemistry to convert a carboxylic acid group into an N-substituted carboxamido group. A preferred method of carboxyl activation is reaction of the carboxylic acid group with N,N'-carbonyldiimidazole. Other methods are e.g. reaction with thionyl chloride, reaction with N,N'-dicyclohexylcarbodiimide to form an activated adduct, reaction with ethyl chloroformate, n-butyl chloroformate and the like to form a mixed anhydride, and reaction with p-nitrophenoxybenzyl chloride to form a p-nitrophenoxybenzyl ester and the like.

The activated 8-carboxyquinoline intermediate is reacted with an aminotetrazole in an aprotic solvent, such as tetrahydrofuran or N,N-dimethylformamide, or in aqueous media in the presence of an acid acceptor, e.g. a tertiary organic base, such as pyridine or triethylamine, or an alkali metal carbonate or bicarbonate. Reactions in aqueous media may require a co-solvent to achieve the reaction. If necessary, elevated temperatures can be used. Preferably, the reaction temperature is 25 - 200°C. The temperature of a particular reaction will normally depend on the solvent used, and will often be the reflux temperature of the mixture.

8-(N-alkyl-1H-tetrazol-5-ylcarbamoyl)quinolines can be easily prepared from known N-alkyltetrazoles or by alkylation of the tetrazole moiety in the corresponding unsubstituted compound

with suitable alkylating agents, such as alkyl-

bromides and iodides. The alkylation will usually result in a mixture of N 1 - and N 2 -substituted compounds. Separation can be accomplished by crystallization or chromatography.

Salts of the compounds in question are produced by reaction with the organic or inorganic base in a non-reactive solvent, where e.g. sodium hydroxide or dimethylaminomethanol is used.

The subject compounds may be combined with a pharmaceutically acceptable carrier or diluent. The nature of this will of course depend on the desired administration method such as e.g. can be oral or by inhalation (oral or nasal), parenteral, e.g. intradermal or intravenous injection, or be a topical application. Such agents can be formulated in the usual way with conventional ingredients, e.g. in the form of solutions, suspensions, syrups, dry powders, tablets, or in the case of topical application in the form of creams, lotions or pastes. Such agents usually contain a small amount of active ingredient and a predominant amount of carrier or thickening agent.

The subject compounds are useful in the treatment of so-called "intrinsic" asthma (where no hypersensitivity to extrinsic antigens can be demonstrated) or any other condition where non-specific factors trigger the release of allergen mediators, and in the treatment of other conditions where anti -gene antibody reaction is responsible for diseases such as ex-trinsic asthma, birth allergies, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, hay fever, urticaria and auto-immune diseases. The treatment may require repeated doses of the agent at regular intervals. The amount administered and the frequency of administration will depend on many factors, and no precise dose range or size can be specified. As a general rule, however, it can be said that when the compounds are administered by inhalation to a patient suffering from acute allergic asthma, therapeutically useful results can be obtained at doses of from 0.1 to 20 mg/kg. When the compounds are administered orally, larger doses are normally given. According to the invention, there is thus provided a method for inhibiting the effects of an antibody-antigen reaction which comprises a prior (which is preferred) or subsequent application of a therapeutically effective amount of a compound according to the invention at the known or expected site of the antibody-antigen reaction mechanism .

Other active substances may also be present in preparations based on the compounds according to the invention. In the case of agents for inhalation, it may be advantageous to include a bronchodilator such as isoprenaline, adrenaline, carbuterol, rimiterol, orciprenaline, isoetharine or derivatives thereof, especially in the form of salts. The amount of bronchodilator used will vary over a wide interval, depending, among other things, on the nature and activity of the specific bronchodilator and the compound in question used. However, it is preferable to use a smaller amount, i.e. under . 50% by weight of the bronchodilator together with 0.1 - 10% by weight of the compound in question. Such agents are also covered by the invention.

The effectiveness of the compounds in question is assessed by inhibiting passive cutaneous anaphylaxis by a standard test method, essentially as described in "Immunology", 16,

749 (1969).

From Norwegian explanatory document 137 899, related compounds are known which have the same qualitative properties as the compounds of general formula I. A comparative study was carried out on the compounds: I. 8-(1H-tetrazol-5-ylcarbamoyl)quinoline (subsequently ex. 1), and II. 2-(1H-tetrazol-5-ylcarbamoyl)quinoline (ex. 1 according to Norwegian publication 137 899).

Sprague-Dawley rats (male and female) with a body weight of approx. 200 g was injected intramuscularly with egg albumin and

intraperitoneally with Bordella pertussis vaccine. 10 to 12 days after this treatment, the rats were bled via the abdominal aorta. The blood was allowed to clot overnight and then centrifuged to collect blood serum containing antibody.

Another group of Sprague-Dawley rats with a body weight of 50 to 120 g was then sensitized to egg albumin by intradermal injection of 0.1 ml of blood serum containing antibody, obtained as described above, into the mid-dorsal region. Sensibility was allowed to develop within 48 hours. Test compounds in 1% "Klucel" vehicle were administered to sensitized rats by oral administration 20 minutes prior to challenge by intravenous administration of egg albumin and Evans Blue dye. For each dose level (expressed as mg of test compound per kg body weight) of the compound to be tested, a group of 6 rats were treated, while 6 rats were treated with only vehicle as a control for each test.

After treatment with the test compound, the rats were challenged by intravenous injection of 1 ml of a mixture of egg albumin (0.5 mg/ml), Evans Blue dye solution (10 mg/ml), and physiological saline. The provocation dose induces an anaphylactic; reaction at the injection site made visible by the dye.

4 5 minutes after injection of egg albumin, the rats were euthanized and the skin was removed and turned over. The intensity of the anaphylactic reaction was determined by comparing the size of the characteristic blue blister formed by diffusion of Evans Blue dye from the site of sensitization. Comparison of the size of the blisters in control animals with the size of the blisters in treated animals made it possible to calculate the percentage inhibition (or percentage reduction) according to the following equation: (Area - control group - area - treated group) x 100

Area - control group

The results obtained were as follows:

A statistical analysis of these results (which also took into account the results of the control tests performed at the same time and using the same group of test animals) indicated that compound I showed a highly significant activity at 0.625, 0.312 and 0.156 mg/kg while compound II showed none statistically significant activity at some of the tested doses.

The following examples illustrate the invention.

Example 1

A solution of 1.0 g (6 mmol) of 8-quinolinecarboxylic acid and 0.98 g (6 mmol) of N,N'-carbonyldiimidazole in 40 ml of N,N-dimethylformamide was stirred at 100°C for 6 hours. To this mixture was added 0.62 g (6 mmol) of 5-aminotetrazole monohydrate in 10 ml of N,N-dimethylformamide. After stirring for 1 hour at 100°C, the solution was evaporated. The residue was diluted with water and approx. 3 ml of 10% hydrochloric acid and was stirred for 1 hour. The solid product was separated by filtration, dried and recrystallized from N,N-dimethylformamide to give 8-(1H-tetrazol-5-ylcarbamoyl)quinoline, m.p.

310 - 315°C (decomposition).

Example 2

A mixture of 2.4 g (0.020 mol) of 8-quinolinecarboxylic acid and 3.0 g (0.030 mol) of 5-amino-1-methyltetrazole was stirred in 30 ml of pyridine at 20°C with the dropwise addition of thionyl chloride. The mixture was heated to 70°C for 1 hour. The reaction mixture was evaporated to form a residue which was diluted with water. The solid was separated by filtration and recrystallized from acetic acid using decolorizing carbon. The product was recrystallized once more from acetic acid to give 8-(1-methyl-1H-tetrazol-5-ylcarbamoyl)quinoline, m.p. 224 - 225°C.

Analogous to example 2, the following compounds were prepared from suitable aminotetrazoles or N-alkylaminotetrazoles and substituted carboxyquinolines.

Example

r

Example 14

To a solution of 1.7 g (10 mmol) of 8-quinolinecarboxylic acid in 50 ml of N,N-dimethylformamide was added 1.6 g (10 mmol) of N,N'-carbonyldiimidazole, and the mixture was stirred for 4 hours at 100° C.

The reactive intermediate formed was reacted with 1.0 g (10 mmol) of 5-amino-2-methyltetrazole. The reaction was carried out by adding the solution and 2 drops of trifluoroacetic acid to the stirred solution of the reactive intermediate and heating for 4 hours at 140 - 150°C. The solution was then evaporated. Water was added to the residue, the mixture cooled and then filtered. The solid was recrystallized from ethanol to give 8-(2-methyl-1H-tetrazol-5-ylcarbamoyl)quinoline, m.p. 222 - 223°C.

Example 15

Analogously to example 2, but using 50 ml of chloroform as solvent, 7-methyl-8-(1H-tetrazol-5-ylcarbamoyl)quinoline was obtained, m.p. 285 - 287°C.

Example 16

To a stirred solution of 4.0 g (0.020 mol) of 2,4-dimethyl-8-quinolinecarboxylic acid in 20 ml of N,N-dimethylformamide in an ice bath was added 2.8 ml of triethylamine. 2 ml of ethyl chloroformate was added dropwise to this solution. The mixture was stirred for 1 hour, after which 2 g (0.020 mol) of 2-aminotetrazole monohydrate in 10 ml of N,N-dimethylformamide were added. The mixture was stirred at 20°C for approx. 16 hours and then evaporated to form a residue which was washed with water. The residue was recrystallized twice from acetic acid to give 2,4-dimethyl-8-(1H-tetrazol-5-ylcarbamoyl)quinoline, m.p. 300 - 305°C.

Claims (1)

Analogy method for the preparation of therapeutic active substituted tetrazoles of the general formula in which R denotes alkyl or alkoxy with 1 or 2 carbon atoms, R 2 denotes alkyl or alkoxy with 1 or 2 carbon atoms, hydrogen, nitro or halogen, R 3 denotes hydrogen or alkyl with 1-4 carbon atoms, and n is 0, 1 or 2 and pharmaceutically acceptable salts thereof, characterized in that 8-carboxyquinoline with the general formula 1 2 .where R , R and n have the meanings given above, is activated and is reacted with an aminotetrazole of the general formula where R 3 has the above meaning.