IE46713B1 - 4-(2-thienylmethylamino)benzoic acid compounds - Google Patents

Abstract

Novel compounds of 4-(thienylmethylamino)benzoic acid and their pharmaceutically acceptable salts, a hypolipidaemic composition containing these compounds and a process for the preparation of these compounds are described. The compounds have the formula below where R is hydrogen or a C1 to C3 alkyl, and X, Y and Z, taken individually, represent H, Cl or Br provided that at least one of X, Y and Z is Cl or Br. These compounds can be used for reducing the lipids level in mammalian blood serum.

Description

This invention concerns halo-substituted 4-(2-thienylmethylamino)benzoic acids, the corresponding esters and salts thereof, a hypolipidemic composition containing same, and-a process for preparing the compounds. 4-(2-Thienylmethylamino)benzoic acid and the corresponding ethyl ester have been described in Izo. Akad. Nauk SSSR, Ser. Khim. 1967(9), 2049-55 (C.A. 63_;104S63K) .

No utility for the compounds is disclosed. Dutch Patent Application No. 7602332 discloses 4[aryl(alkyl or alkenyl)amino]benzoic acid compounds having hypolidemic activity.

The present invention provides 4-(2-thienylmethylamino)benzoic acid compounds corresponding to the general formula: CCOR wherein R represents hydrogen or alkyl, and X, Y, and 3 independently represent hydrogen, chloro, or bromo, with the proviso that at least one of X, Y, and 2 is chloro or bromo.

Pharmaceutically-acceptable salts of the p-aminobenzoic acids, i.e. when R is hydrogen, are also considered as being within the scope of this invention. Pharmaceutically-acceptable salts'refer to the acid addition salts of those bases which will form a salt with a carboxylic acid and which will not cause an adverse physiological effect when administered to an animal at dosages consistent with good pharmacological activity. Suitable bases thus include, for example, the alkali metal and alkaline earth metal hydroxides, carbonates, and bicarbonates such as sodium hydroxides, potassium hydroxide, calcium hydroxide, potassium carbonate, sodium bicarbonate, or magnesium carbonate; ammonia, primary, secondary, and tertiary amines. Also, aluminum salts may be obtained by treating the corresponding sodium salt with an appropriate aluminum complex such as aluminum chloride hexahydrate.

Compounds of the present invention have shown hypolipidemic activity in animals and in particular In mammals. Hypolipidemic activity as used herein radars to the effect of lowering the blood lipid content ar.d in particular the cholesterol and triglyceride content of the serum. The compounds are therefore suitable for use in treating serum hyperipidetda in mammals and in particular are useful for the treatment of hypercholesterolemia and hypertriglyceridemia, that is, abnormally high levels of lipids, cholesterol, or triglycerides, respectively, in the serum. The compounds can be administered orally or parenterally by subcutaneous, intravenous, or intraperitoneai injection or by implantation, oral administration being preferred.

The effective hypolipidemic amount of the c-aninobenzoic acid compounds to be administered to an animal, that is, the amount which is effective to significantly lower the serum lipid level, can vary depending upon such factors as the animal treated, the particular compound employed, the desired lipid level to be obtained, whether or not the animal is hyperlipidemic, the period of administration, and the method of administration. In general, an effective daily dosage range is from about 1 mg/kg of body weight to 200 mg/kg of body weight, with a daily dosage range of from about 10 mg/kg to 100 mg/kg of body weight being preferred.

For oral administration, pharmaceutical preparations of the p-aminobenzoic acids may be made by following conventional techniques. These techinques involve granulating and compressing, when necessary, or variously mixing and dissolving or suspending the ingredients as appropriate to the desired end product. Numerous pharmaceutical forms to carry the compounds can be used. For example, the pure compound can be used or it can' be mixed with a solid carrier. Generally, inorganic pharmaceutical carriers are preferable and particularly solid inorganic carriers. One reason for this is the large number of inorganic materials which are , known to be pharmaceutically safe and acceptable, as well as very convenient in preparing formulations. The compositions may take the form of tablets, linguets, powders, capsules, slurries, troches, or lozenges, and such compositions may be . prepared- by standard pharmaceutical techniques. Tablet ' compositions may be coate’d or uncoated, and they may be effervescent or non-effervescent. Conventional excipients for tablet formations may be used. For example, inert Γ I 20 diluents, such as magnesium carbonate or lactose, disintegrating agents such as maize starch or alginic acid, and lubricating agents such as magnesium stearate may be used.

If a liquid carrier is used, the preparation may be in the form of a soft gelatin capsule, a syrup, a liquid solution, or suspension.

The hydrocarbon solubility of most of the compounds of this invention is high enough to allow the use of pharmaceutically-acceptable oils and carriers. For example, vegetable or animal oils such as sunflower oil, safflower oil, maize oil or cod liver oil can be used. Glycerine can also be used. With this latter solvent, from 2 to 30 percent water, may be added. When water alone is the carrier, or when the solubility of the compound in the oil is low, the preparations can be administered in the form of a slurry.

Emulsion compositions may be formulated using emulsifying agents such as sorbitan trioleate, polyoxyethylene sorbitan monooleate, lecithin, yum acacia, or gum tragacanth. Aqueous based suspensions may be prepared with the aid of wetting agents such as polyethylene oxide condensation products of alkylphenols, fatty alcohols, or fatty acids with the suspending agents, for example, a hydrophilic colloid such as polyvinylpyrrolidone. The emulsions and suspensions may contain conventional excipients such as sweetening agents, coloring materials, or preservatives.

The compounds can also be incorporated in a nutritive foodstuff such as, for example, butter, margarine, edible oils, casein, or carbohydrates. Such nutritive compositions are adapted to be administered as a partial or total diet or as a supplement to the diet. Such compositions preferably contain from about 0.32 tc about 2.0 percent of the active ingredient when administered as the total diet. The compositions can contain higher concentrations of the active ingredient when administered as a supplement. for parenteral use, the compounds can be formulated with sterile ingredients, compounded, and packaged asceptically. They may be administered intravenously or intramuscularly. Useful solvents for formulation for such use are the polyhydric aliphatic alcohols and mixtures thereof.

Especially satisfactory are the pharmaceutically acceptable » glycols, such as propylene glycol, and mixtures thereof. Glycerine is particularly useful. Up to 25-30 percent by volume of water may be incorporated in the vehicle, if desired. An 80 percent aqueous propylene glycol solution is a particularly convenient solvent system. A pH of about 7.4 and isotonicity compatible with body isotonicity are desirable. Basicity may be controlled by addition of a base as required, and a particularly convenient base is monoethanolamine. It may often be desirable to incorporate a local anesthetic and such are well known to those skilled in the art.

The percentage of the compound to be used in the pharmaceutical carrier may be varied. It is necessary that the compound constitute a proportion such that a suitable dosage will be obtained and it is preferred to use pharmaceutical compositions containing at least 10 weight percent of the compound. Activity increases with concentration of the agent in the carrier, but those compositions containing a significant amount of carrier, e.g. at least 1 percent and preferably at least 5 percent, are preferred as they alio»? for the easier administration of the compound.

The active compounds of the present invention are prepared by known procedures. In general, member compounds are made by reacting p-aminobenzoic acid or an ester thereof in an inert solvent with a halo-substituted 2-thiophenecarboxaldehyde. The resulting Schiff base is reduced to prepare the corresponding p-aminobenzoic acid derivative.

A convenient method of carrying out this latter procedure involves mixing the Schiff base with an excess of ethanol and water. Dilute aqueous sodium hydroxide optionally can be added to the mixture. Sodium borohydride is added at ι room temperature and stirred until it dissolves. The mixture is then heated, poured onto ice, and acidified. The product may he filtered off as a precipitate and further purified by known procedures.

Several of the halogenated aldehydes were not readily available and were prepared by methods generally known from the literature. For example. 4-chioro-2-tnicphenecarboxaldehyde was prepared by the ch-otmatim ti 1thiophenecarbcxaldehyde using a large excess of the aluminum chloride catalyst. See J. Org. Chem., 21 381 (1956) and J, Heter. Chem., 393 (1976). Using the same method 4,5dichloro-2-thiophenecarboxaidehyde was also prepared from, 5-chlorc-2-thiophenecarboxaldehyde. See C.A. 57;16526i.

The following examples further illustrate the invention.

Example 1 4-t3,5-Dichloro-2-thlenylm3thylamino)benzoic acid A 50% oil dispersion (5.3 grams, 0.12 mole) of sodium, hydride was washed with hexane under nitrogen. To this, 230 ml of dry dimethylformamide and 29.5 grams (0.113 mole) of solid ethyl N-trifluoroacetyl-4-aminobenzoate was added. The reaction mass exothermed mildly. The mixture was cooled to 20°C and stirred for 15 minutes. Afterwards, 27.7 grams of 3,5-dichloro-2-bromomethyithiophene was added. The reaction mass was heated for 13 hours at 33°C. At uh» end of that period the mixture was poured into 1 liter cf cold water and extracted with methylene chloride. The product was dried with anhydrous sodium sulfate and the dried solution concentrated to a brown oil. The resulting oil was refluxed for 2 hours with SC mi of ethanol and 203 mi of th sodium hydroxide. The cooled, brown solution was diluted with water and acidified with acetic acid. The crude. 4-(3,, 5-dichloro-2-thienylmethylamino) benzoic acid was obtained as *a brown gum, and recrystallization from propylene glycol methyl ether gave 17 g. brown crystals, m.p. 169-170.5°C.

Elemental analysis: C H N Calculated 47.71 3.00 4.63 Found -47.8 3.06 4.74 Example 2 4- (5-Chloro-2-thienylmethylamino, benzoic acid A mixture containing 46.6 grams (0.34 mole, of • 10 p-aminobenzoic acid, 50 grams (0.34 mole, of 5-chloro-2thiophenecarboxaldehvde, and 400 ml. of toluene was heated \ to reflux for about 3.5 hours. The water formed was collected ( in a Dean-Stark trap. The reaction mass was cooled at the end of this period and the Schiff base collected as a tan 15 solid. To a mixture of the intermediate Schiff base and 1.2 * liters of glacial acetic'acid 21.2 grams (0.35 mole, of dimethylaminoborane was added. The reaction mass was wanned to 40°C for about 30 minutes and poured in 2 liters of ice water. The white precipitate of 4-(5-chloro-2-thienylmethvlf 1 20 amino)benzoic acid was washed in water, dried, and recrystallized from toluene. Yield, 60 g. (70%, ; m.p. 177-178°C.

Example 3 4-(4,5-Dichloro-2-thienylmethylamino)benzoic acid Step 1: Synthesis of 4,5-dichloro-2-thiophenecarboxaldehyde.

To a mechanically stirred solution of 31.S grams (0.217 mole) 5-chloro-2-thiophenecarboxaldehyde in 150 ml of methylene chloride, 65 grams (0.487 mole, of anhydrous aluminum chloride was added in small portions. The mixture exothermed and turned purple. To this mixture 20.6 grams (0.29 mole) of chlorine in 250 ml of carbon tetrachloride was added dropwise. The reaction mass was refluxed for about 15 hours, and an additional 15 grams (0.21 mole) of chlorine in 200 ml of carbon tetrachloride was added. The mixture was refluxed for an additional 7 hours. The reaction was quenched by pouring over one liter of ice water. The aqueous layer was extracted with chloroform. The chloroform solution was wasnec witn water ane sodium mcarrcnate. *-,ruer drying with anhydrous sodium sulfate and concentration under vacuum, ?. yellow-brown oil was obtained. The crude 4,5dichloro-2-thiophenecarbcxaldehyde crystallized on standing and was recrystallized from hexane.

Step 2: The product 4-(4,5-dichloro-2-thienylmGthylamino)benzoic acid, m.p. 225-227sC, was prepared from the 4,5-dichloro-2-thiophenecarboxaldehyde intermediate in essentially the same manner as described in Example 2 above; yield, 88%.

Elemental analysis: C H Calculated 47.71 3.33 4.63 20 Found 47.6 3.09 4.80 In addition to the compounds described in the examples above, other compounds were prepared using essentially the same techniques. These compounds shown as Examples 4, 5 and 6 were as follows: Sxamoie 4 4- (5-Chloro-2-thienyl;nethyIanu.no)benzoic acid ethyl ester, m.p. 102-109eC, was prepared from ethyl raminobenzoate and 5-chloro-2-thiophenecarboxaldehyde. Yield, 87%.

Elemental analysis: C H Ji_ Calculated 56.86 4.77 4.73 Found 56.7 4.87 4.85 Example 5 4-(5-Bromo-2-thienylmethylamino)benzoic acid, m.p. 188-190°C. Yield, 61%. Elemental analysis: C H N Calculated 46.18 3.23 4.49 Found 46.1 3.29 4.65 Example 6 4-(4-Chloro-2-thienylmethylamino)benzoic acid, m.p. 165-168°C. Yield, 96%.

Elemental analysis: C H N Calculated 53.85 3.77 5.23 Found 53.6 3.80 5.38 Example 7 The hypolidemic effect of the compounds of the invention was illustratively demonstrated in rats. In this procedure, a compound was dissolved in acetone, taken up on , t 20 a silica gel, and mixed with normal ground feed to yield ' concentrations of 0.125 percent of the compound in the animal feed. The treated feed was administered to male rats weighing 150-160 grams over a 14 day period. Following the feeding period, the rats were sacrificed, and the blood samples were collected. The liver was removed, weighed, and frozen for future analysis. The relative levels of serum cholesterol in the blood samples were determined by the Henly method. A. A. Henly, Analyst, 32, 286 (1957) . Liver cholesterol was measured by the Sperry-Webb method.

Journal Of Biological Chemistry 187, 97 (1950). The * ti < id relative levels of triglycerides in the blood and liver samples were determined by the Von Handel and Zilversmit method. J. lab. Clin. Med. 30, 152 (1957) and Clin. Chem. ,, 249 .a36i). Taking the average levels of the control rats as standard, the mean results obtained in the treated groups is thereby ascertained.

The data presented in Table 1 summarizes the results of the above studies. &. b ’< tJ A3 rfj Ε-» * μ ΜΛ Φ CP > ·Η «μ φ ►4 3 * +) r& O> Ο ·Η CQ Φ * «Λ Φ Ό •W μ μ φ Φ > 0 •rl >1 jfird Oi •h μ El •is H iM Μ Φ Q) -U > OJ •Η Φ ifird O XJ U * ω Φ Ό Ή ε Μ s φ U 0 Φ > W H Oi •rl M 5h * r4 0 μ ε φ □ -μ μ « Φ φ Ό Ζ fi fi Φ Ο Η α ο· ε ε ο «ί Ο X W CO rd' CM O ό rd rd CM + 4- 4- 4- 4- *a« σ\ Η co I I 4CO 4· I-i rd rd ί I ΓΗ + 53. rd 4· ΙΛ CO kD rd *5* O in in <0 in 10 I I 1 I I I H *5f CO CM O in co co -4· co co I I J I I Ό Φ μ nJ a ε o □ c φ Λ (Ω rd cd S •H C Φ Ό Φ •μ Φ Φ μ μ φ χ: +J μ ο ιμ w φ fi rd Φ > fi •Η Φ Οι C Φ Λ Ο 4J fi Φ Ο μ φ · α» ο» fi •μ ο « μ Φ Οι (0 Φ rd μ ο ρ^μ φ χ> μ c ο φ ο -μ φ φ ό χ; <μ Η rd ο * The data in Table I Indicate that the compounds of the present invention are highly effective as hypolidemic agents in the lowering of serum cholesterol and serum trijiycariGcs while causing only minimal changes in liver weight and overall body weight. The compounds 4-(4,5-dichioro-2-thienylrethyIaxirio)benzoic acid (Example 3) and 4-iS-chloro-l-thienylteohylimino)bencoic acid ethyl ester (Example 4} -:re shown to he especially u.safu. covering cholesterol levels in mammals. Likewise -he compounds 4-(5-chlcro~2-thienylmethyiamino)benzoic acid ethyl ester (Example 4) and 4-(4"Chloro-2-thisnylmethyiar.inc)benzoic acid (Example 6) were found to be particularly effective in lowering serum triglycerides .

Claims (13)

1. 1. . A 4-(2-thienylmethylamino)benzoic acid compound corresponding to the formula: Y-r--r-X 3 CH 2 NH -/θν -COOR T5 wherein R represents hydrogen or C^_ 3 alkyl, and X, Y, and Z independently represent hydrogen, chloro, or bromo with the proviso that at least one of X, Y, and Z is chloro or bromo, and pharmaceutically-acceptable salts thereof.

2. 4-(3,5-Dichloro-2-thienylmethylamino)benzoic acid.

3. 4-(5-Chloro-2-thienylmethylamino)benzoic acid.

4. , 4-(4,5-dichloro-2-thienylmethylamino)benzoic acid.

5. 4-(5-Bromo-2-thienylmethylamino)benzoic acid.

6. 4-(4-Chloro-2-thienylmethylamino)benzoic acid

7. 4-(5~Chloro-2-thienylraethylamino)benzoic acid ethyl ester.

8. A hypolipidemic composition comprising a pharmaceutical carrier and a 4-(2-thienylmethylamino)benzoic acid compound claimed in any one of Claims 1 to 7.

9. A process for preparing a 4-(2-thienylmethylamino) benzoic acid compound claimed in any one of Claims 1 to 7 which comprises reacting a 4-aminobenzoic acid compound corresponding to the formula NH, COOR with a 2-thiophenecarboxaldehyde corresponding to the 'Attiula Cnd wherein R, X, 7, and X are as defined in Claim 1, followed by redaction 5 of the Schiff base thus formed.

10. A process according to Claim 9 in wnich the product is a compound as claimed in any of Claims 2 to 7.

11. A process for preparing a compound as claimed in Claim 1 substantially as describee in any of the examples. 10

12. A compouno as claimed in Claim 1 when prepared by a process according to any of Claims 9 to 11.

13. A pharmaceutical composition comprising a compound as claimed in any of Claims 1 to 7 and 12 in association with a physiologically acceptable excipient.