AU627609B2

AU627609B2 - New quinoline derivatives and process for the preparation thereof

Info

Publication number: AU627609B2
Application number: AU60725/90A
Authority: AU
Inventors: Magdolna Czeller; Ilona Imre; Jozsef Jeko; Zoltan Salamon
Original assignee: Alkaloida Chemical Co Zrt
Current assignee: Alkaloida Chemical Co Zrt
Priority date: 1989-07-25
Filing date: 1990-07-20
Publication date: 1992-08-27
Anticipated expiration: 2010-07-20
Also published as: AU6072590A

Description

New quinoline derivatives and process for the preparatio thereof

The present invention is directed to a process for the preparation of quinoline derivatives of the general formula (I)

wherein stands for hydrogen or a group of the formula (II)

by reacting a halogene quinoline derivative of the general formula (III)

wherein

X stands for chlorine or bromine - with picoliπe oxide of the formula (IV)

in the presence of alkali-t-alkylate, preferably potas- sium-t-butylate or b) oxydizing a compound of the formula (V).

The definition of the substituents is as follows:

R stands for hydrogen or a group of the formula (II) X stands for chlorine or bromine.

The novel compounds according to the present inven¬ tion are important intermediates for the preparation of pharmaceutically active compounds. Thus, for instance the novel compounds are valuable intermediates of erithro- -alfa-2-piperidyl-2,8-bis(trifluor-methyl)-quinoline- -4-methanol-hydrochloride (meflokin). This latter active ingredient can be successfully used in pharmaceutically active compositions against malaria.

Meflokin has been first prepared (see 3 . Med. Che . l±, 926 (1971)) by reacting a 2,8-bis(trifluor- -methyl)-quiπoliπe-4-carboxylic acid syπthetized in three steps with 2-lithio-pyridine and by hydratiπg the obtained 2-pyridyl-2 , 8-bis(trifluor-methyl)-quinolyl- -ketone ("Ketone") above Adams-catalyst. From the above quinoline carboxylic acid intermediate the ketone was obtained also by reacting it with 2-bromo-magnesium- pyridiπe (DOS 29 40443), and by hydrating the "ketone" analogously to meflokin above a platina charcoal cata¬ lyst. The unisolated intermediate of the reduction step (2-piridyl)- -2,8-bis(trifluor-methyl)-quinoline-4-methanol is referred to hereinafter as "Oxy-methane. This compound can be obtained also by reacting 4-lithio-quinoline derivatives obtained from 2 , 8-bis(trifluor-methyl)-4-bromo-quinoline by lithiation with 2-pyridine-aldehyde (DOS 28066909). According to a newer technical solution the metallation step is eliminated and thereby a cheeper starting mate¬ rial can be used compared to the so far known quinoline intermediates. When reacting 2,8-bis(trifluor-methyl)-4- -chloro-quinoline with 2-pyridyl-acetonitrile or with 2-pyridyl-methyl-phosphonium salt the obtained inter¬ mediate results in ketone by oxidation. According to the authors in these cases in order to subject the halogen of the quinoline in 4-positioπ to nucleophil substitution the pyridiπe reactaπt has to contain on the methyl group an electron withdrawing substitueπt (see the above mentioned carbonitrile or phosphonium group) (EP0049776).

In EPA 0049 776 in Example 1 the aromatic nucleophil substitution of 2-methyl-pyridine-N-oxide has been men¬ tioned which was carried out with sodium amide in di- ethoxy-ethane, but the structure of the obtained product has not been determined, no physical-chemical data were given and the reference was already cancelled from the granted patent.

The above mentioned processes have several disad¬ vantages, such as the already mentioned metallation steps or the expensive quinoline intermediates (such as 2,8-bis(trifluoro-methyl)-4-bromo-quinoline or the corresponding quinoline-4-carboxylic acid) and the pyri- dine derivatives are expensive and not easily accessible. These disadvantages could be successfully eliminated by using a quinoline intermediate of the general formula (III) and 2-methyl-pyridine-N-oxide. The quinoline inter¬ mediate of the general formula (III) is prepared by our method disclosed in USP 45 99 345 and USP 46 59 834 which is also suitable for the industrial synthesis of 2,8-bis(trifluoro-methyl)-4-chloro-quinoline. We have now found that as opposed to the teaching of EP 0 049 776 the electron withdrawing substituent is not necessary on the methyl group of picoline as the cheaper and easier accessible 2-methyl-pyridine-N-oxide can be reacted without the electron withdrawing substi- tuent as well. According to the present invention di(2,8-bis(tri- fluor-methyl)-quinoline-4-yl)~N-oxy-2-pyridyl-me hane can also be prepared depending on the circumstances. This compound is novel. By using the suitable condensat- ing agent or an excess of 2-methyl-pyridine-N-oxide depending on the solvent and/or by using a dilute reac¬ tion mixture substantially only moπo-quinolyl-derivative is obtained.

According to process a.) of the present invention one may preferably proceed by reacting a halogene-quino- line-derivative of the general formula (III) with 2- -methyl-pyridine-N-oxide in the presence of potassium tertiary-butylate and as reaction medium tertiary alcohols or inert solvents, such as aromatic hyrocarbons, cyclic or acyclic ethers, dimethyl-formamide, dimethyl-sulphoxide preferably toluene or tetrahydrofuraπ are used.

According to the process variant b.) one may prefer¬ ably oxidize a compound of the formula (V) with per acids, preferably with per acetic-acid or hydrogen-peroxide. The starting material of process variant b.) is the compound of the formula (V) or salts thereof which compounds are new. The compound of the formula (V) can be prepared from the derivatives of the formula (VI)

or (VII )

by eliminating the nitrile or =0 group.

The elimination of the nitrile group can be per¬ formed in an acid medium, such as sulphuric acid by heating in the presence of water.

The product can be obtained after neutralizing the reaction mixture by purification in a solvent in a crystalline form. The elimination of the oxygen from the ketone derivative can be performed by catalytic reduction with hydrogen or transfer hydrogenolysis , preferably by a treatment with ammoπium-formiate in the presence of a metal catalyst or formic acid.

The present invention also extends to the novel compounds of the general formula (I), to the novel com¬ pound of the formula (V) and salts thereof.

The novel compounds according to the invention can be isolated from the reaction mixture as outlined in the following examples. If the compounds have to be converted to oxymethane by rearranging, then isolation from the reaction medium is not necessary, if the re- arraπgmεnt is carried out by the method of our copending Hungarian patent application No. 3736/89.

The details of the present invention are shown in the following examples. Example 1

12.73 g of potassiu -tert.-butylate and 6.20 g of 2-methyl-pyridine-N-oxide and 50 ml of tetrahydro- furan are mixed and to the mixture 3 g of 2,8-bis(tri- fluor-methyl)-4-chloro-quinoline are added at 60 °C. The mixture is allowed to cool to room temperature and 5 ml of glacial acetic acid is added dropwise under aqueous cooling to the mixture and the precipitated inorganic salt is filtered and washed with 2 x 20 ml ether. The organic layer is evaporated to dryness and the residual 9.31 g of product is admixed with an 1:1 mixture of ice and methanol, it is filtered, washed with water and dried. 3.42 g of N-oxy-2-pyridyl)-2,8- -bis(trifluor-methyl)-quiπαline-4-methane are obtained. M.p.: 156 - 158 °C. An analytically pure sample is recrystallized twice from ethanol, m.p.: 162 - 162.5 °C.

Example 2

16 g of potassium are dissolved in hot tertiary- -butanol and the obtained potassiu -tert.-butylate is suspended in 350 ml of toluene. To the suspension 21.8 g 2-methyl-pyridine-N-oxide and 24.1 g 2,8-bis(trifluor- -methyl)-4-bromo-quiπoline are added at 45 °C. The mix¬ ture is cooled to 20 C and under external cooling 125 ml of 10 % hydrochloric acid are added, the aqueous layer is separated and extracted with toluene. The organic layer is dried, clarified with active charcoal and evaporated to 150 g at reduced pressure. The mixture is cooled and the precipitated crystalline product is filtered. 20.12 g of (N-oxy-2-pyridyl)-2,8-bis(tri- fluor-methyl)-quiπoline-4-methaπe are obtained. Mp.: 157 - 158 °C.

Example 3

To 100 ml of a 25 % so tioπ of potassium-tert.- -pentylate in toluene 6 g oi 2-methyl-pyridine-N-oxide and 3.44 g of 2,8-bis(trifluor-methyl)-4-bromo-quiπoline are added according to Example 1. 3.57 g of (N-oxi- -2-piridil)-2,8-bis(t ifluor-methyl)-quinoliπe-4-methane are obtained. Mp.: 155 - 157 ° _ Example 4

To a solution prepared from 3.21 g of potassium metal and 80 ml of anhydrous ter .-butanol 4.4 g of 2-methyl-pyridine-N-oxide are added, the mixture is heated to 70 °C and 4.2 g of 2 ,8-bis(trifluor-methyl)-4-chloro- -quinoline are added. When the reaction is terminated the pH is adjusted to 6 by adding concentrated hydro¬ chloric acid solution, the mixture is stirred for 10 minutes at 25 °C, the precipitated substance is filtered and covered with 10 ml of ter . -butanol. The mixture is concentrated by suction, dissolved in 100 ml of water and the insoluble part is filtered off and dried. 1.14 g of the product is obtained. Mp.: 264 - 265 °C. After recrystallization from methaπol: Mp.: 271 - 272 °C. According to MS ¹H- and ¹³C-NMR the product is di(2,8- -bis(trifluor-methyl)-4-quinolyl)-(N-oxy-2-pyridyl)- -methane. From the aqueous tert-butanolic mother lye the tert.-butanol is distilled off and the residue is diluted with 100 ml of water, extracted with 3 x 50 ml chloroform, dried above sodium-sulphate and evaporated. After recrystallization of the residue 3.46 g of (N- -oxy-2-pyridyl)-2,8-bis(trifluor-methyl)-quinoline-4- -methane are obtained. Mp.: 159 - 161 °C. Example 5

At 10 °C 350 ml of potassium-tert. -butylate are admixed in 2250 ml of hexane and 100 g of 2-methyl- -pyridine- -oxide are added. At this temperature the mixture is^' stirred for 1 hour, whereafter 100 g of 2,8-bis(trifluor-methyl)-4-chloro-quinoline are added dropwise dissolved in 200 ml of hexane and after 6 hours of stirring at a temperature below 20 °C the mixture is neutralized by acetic acid. After 90 minutes the precipitated substance is filtered, washed with hexane, dried, admixed with 1000 ml of water and the insoluble raw product is filtered, washed with water and dried. 102.5 g of (N-oxy-2-pyridyl)-2,8-bis(trifluor- -methyl)-quinoline-4-methane are obtained. Mp.: 152 - 154 °C. Active ingredient content according to HPLC 83.2 %.

Example 6 To a mixture of 2250 ml of toluene and 250 g of potassium-tert-butylate of a temperature 0 - 5 °C 70 g of freshly distilled 2-methyl-pyridine-N-oxide are added. After stirring for 10 minutes 100 g of 2,8-bis(tri- fluor-methyl)-4-chloro-quinoline are added dropwise in 150 ml of toluene within 60 minutes. After 90 minutes stirring the reaction mixture neutralized with glacial acetic acid is extracted with water. The residual toluene solution is clarified, filtered, evaporated and cooled. The precipitated crystalline product is filtered, covered with some toluene and dried. 89.9 g of (N-oxy-2-pyridyl)- -2,8-bis(trifluor-methyl)-quinoline-4-methaπe are obtained Mp.: 157 - 159 °C. The product is of 95.6 purity according to HPLC. Example 7

125.0 g of potassium-ter . -butylate are dissolved in 2250 ml of abs . tetrahydrofuran , the mixture is cooled to 0 - 5 °C and after adding 50.0 g of 2-methyl- -pyridiπe-N-oxide 100 g of 2 , 8-bis(trifluor-methyl)- -4-chloro-quiπoline dissolved in 150 ml of tetrahydro- furan are added dropwise. The solution is neutralized with acetic acid at a temperature below 20 °C, the precipitated salt is filtered, and washed with tetra- hydrofuran. The tetrahydrofuran solution is evapor¬ ated to a 1/10 volume and the precipitated product is filtered, washed with water and dried. 95.6 g of (N-oxy-2-pyridyl)-2,8-bis(trifluor-methyl)-quinoline- -4-methaπe are obtained. M.p. : 159 - 161 °C.

The purity of the product according to HPLC = 96.3 %. Example 8

1.0 g 2-pyridyl-2 , 8-bis(trifluor-methyl)-quiπoliπe- -4-methaπe is dissolved in 10 ml of glacial acetic acid, and after adding 1.0 ml of 30 % hydrogen-peroxide the mixture is maintained at 80 C for 90 minutes. The reaction mixture is poured on ice and extracted with chloroform. The organic layer is dried above sodium sulphate, evaporated and after recrystallization of the residue from 10 ml of ethanol 1 g of (N-oxy-2-pyridyl)- -2 ,8-bis(trifluor-methyl)-quiπoline-4-methaπ is obtained. Example 9

10 g of 2-pyridyl-2 ,8-bis(trifluor-methyl)-quinoline- -4-acetonitrile are boiled under reflux for 5 hours in 70 % sulfuric acid, the mixture is allowed to stand overnight, poured on ice and alkalized with concentrated ammonia to pH 9-10. The mixture is extracted with dichloro- -ethane and the extract is dried above sodium sulphate and evaporated. The residue is crystallized from hexane and 6.47 of 2-pyridyl-2,8-bis(trifluor-methyl)-quinoline- -4-methaπe are obtained. Mp.: 62 - 63 °C. Example 10

Under vigorous stirring 5 g of 2-pyridyl-2,8-bis- (trifluor-methyl)-4-quiπoliπe-ketone are maintained at 60 C in 50 ml of 98 % formic acid in the presence of 2 g of 10 % Pd/C catalyst. In small portions 0.85 g of ammonium formiate are added. When the reaction is completed the catalyst is filtered off and the reaction mixture is evaporated. The residue is poured on ice and the mixture is worked up according to Example 9. 4 g of 2-pyridyl-2,8-bis(trifluor-methyl)-quinoline- -4-methane are obtained and the product melts after recrystallization from hexane at 57 - 58 °C.

Claims

C L A I M S

1. Process for the preparation of quinoline deriva¬ tives of the general formula (I)

wherein 1 stands for hydrogen or a group of the formula (II)

which comprises a.) reacting a halogene-quinoline-derivative of the general formula (III)

wherein X stands for chlorine or bromine - in the presence of alkali-t-alkylate with rC-picoline-N-

-oxide of the formula (IV)

or b.) oxydizing a compound of the formula (V)

2. A process as claimed in claim 1 which comprises reacting a halogene-quinoline derivative of the general

2 formula (III), wherein X is as given above, with {- -picoline-N-oxide in the presence of potassium-tert .- -butylate.

3. A process according to claim 2 which comprises using tertiary-alcohols, inert solvents, such as aromatic hydrocarbons, cyclic and acyclic ethers, dimethyl-form¬ amide, dimethyl-sulphoxide, preferably toluene or tetra- hydrofuran as reaction medium.

4. Process b.) according to claim 1 which comprises oxydizing the compound of the formula (V) with per acids such as per acetic-acid or hydrogene-peroxide.

5. Compounds of the general formula (I) wherein R stands for hydrogen or a group of the formula (II) as well as salts of these compounds.

6. A compound of the formula (V) and salts thereof.

7. A process for preparing a compound of the formula

(V) which comprises eliminating nitrile or =0 from a compound of the formula (VI)

or (VII)