CS235167B1 - Substituted 4,9-dihydro-3-methyl-4-oxo-1H-pyrazole (3,4-b quinolines and process for their preparation) - Google Patents

Abstract

The invention relates to substituted 4,9-dihydro-3-methyl-4-oxo-1H-pyrazolo (3,4-b) quinolines of the general formula I CHj (I) where R* 1 and R2 denote a hydrogen atom, or R1 and R2 denote a methyl group, or R1 is a methyl group and R2 is an ethoxycarbonylmethyl group or a carboxymethyl group, and a method for their preparation. These new, previously undescribed substances exhibit antiviral activity against the Hong Kong influenza A virus and against the mouse encephalomyocarditis virus.

Description

The present invention relates to substituted 4,9-dihydro-3-methyl-4-oxo-1H-pyrazolo [3,4-b] quinolines of formula I

CH 1 (I) wherein R ¹ and R ^{2 are both} hydrogen, or R ¹ and R ^{2 are} methyl, or R ¹ is methyl and R ² is ethoxycarbonylmethyl or carboxymethyl, and processes for their preparation.

These novel substances, which have not been described yet, exhibit antiviral activity against influenza A virus - Hong Kong and against the encephalomyocarditis virus in mice.

The invention relates to substituted 4,9-dihydro-3-methyl-4-oxo-1H-pyrazolo [3,4] quinolines of formula I

wherein R ¹ and R ^{2 are both} hydrogen, or R ¹ and R ^{2 are both} methyl or R ¹ is methyl and R ² is ethoxycarbonylmethyl or carboxymethyl.

These novel substances have not yet been shown to have antiviral activity against A2-Hong Kong virus and against encephalomyocarditis virus (EMC) in mice.

The compound of formula (I) wherein both R ¹ and R ² is hydrogen may be prepared according to the invention by cyclization of the known 3-anilino-5-methyl-4-pyrazolecarboxylic acid (Crenshaw RR, Luke MG, Siminoff P .: J. Med. Chem., 19, 262 (1976) with polyphosphoric acid at a temperature of 80 ° C to 150 ° C, preferably at 90 ° C.

A compound of formula I wherein both R ¹ and R ² is, methyl, may be prepared according to the invention by alkylation of a sodium salt known per se

4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinolines [Stein, R.G., Biel, J. H .: J. Med. Chem. 13, 153 (1973)], methyl iodideim in dimethylformamide at 0 ° C to 30 ° C, preferably at 20 ° C.

A compound of formula I wherein R ¹ is methyl and R ² is carboxymethyl can be prepared by alkaline saponification of a compound of formula I wherein R ¹ is methyl and R ² is ethoxycarbonylmethyl. The saponification is carried out with an aqueous methanolic sodium hydroxide solution at a temperature of 0 ° C to 30 ^° C, preferably at a temperature of 20 ° C.

A compound of formula I wherein R ¹ is methyl · and R ² is ethoxycaribonylmethyl · can be prepared according to the invention by alkylation of 4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinolines ethyl bromoacetate in acetone in the presence of potassium carbonate and potassium iodide at reflux.

Said compounds according to the invention belong to the group of substances with antiviral effects. For these compounds, these effects were detected and evaluated against the A2-Hong Kong influenza virus and the encephalomyocarditis virus (EMC) in mice.

Evaluation of efficacy against A2-Hong Kong influenza virus in mice

Female white SPF mice (Velaz) weighing 10 to 11 g were used. The virus was administered to mice under light ether anesthesia intranasally. The amount of LD 50 of the virus was determined in a separate experiment and was calculated according to REED and MUENCH (Reed L. J., Muench H .: Amer. J. Hyg. 27, 493 (1938)). Three virus concentrations of ο · 1 order were chosen for testing antiviral activity. 7 mice were used for each recovery. Untreated mice died of pneumonia according to the virus concentration used 3 to 10 days after infection. Test substances were dissolved in distilled water, insoluble were suspended with oleic acid monoester and tripolyethylene glycol anhydrobisether (Tween 80). Animals were administered per os by gavage, or were administered subcutaneously into the skin lash on the back in a volume of 0.2 ml each. Mice were treated twice daily for 5 days (1 day before and 4 days after infection). The daily doses were 2 x 150 mg / kg. Efficacy was assessed by increasing the average survival time compared to the untreated control.

Following oral administration, the compounds of formula I were active wherein R ¹ is methyl and R ² is carboxymethyl (extending the survival time of mice against the 5 LD 50 virus by 42% and against 50 LD 50 virus by 20%) and wherein R ¹ is methyl and R ² is ethoxykarbonylmethýlskupina (.prodlužuje survival time of mice against · 50 LD50 virus by 36 ° / o).

The efficacy values of the compounds of formula I against influenza virus · A2-Hongkong in mice following subcutaneous administration are summarized in Table I and are shown in% increase in mean survival time.

TABLE I

R ¹ R ² 0.5 LD 50 5 LD 50 50 LD 50

Η H 72 37 0

CH3 CH2COOC2H5 30 54 7

CH3 CH2COOH-16 11

CH3 CH3-32 48

Evaluation of efficacy against EMC virus in mice

Female white SPF mice (Velaz) weighing 10-11 g were used. The virus was injected subcutaneously in a volume of 0.2 ml into the fold of the back skin. Untreated mice died of virus concentration 3 to 7 days after infection. The amount of virus was determined as described for efficacy against influenza virus. Suibcutaneous treatment was performed in four doses of 100 mg / kg each 28, 22 hours before and 2 hours after infection. Oral treatment was performed 24 hours prior to infection with a single dose of 400 mg / kg. The efficacy evaluation was performed in the same way as the efficacy evaluation of the anti-influenza agents.

The efficacy values of the compounds of Formula I against EMC virus in mice following subcutaneous administration are summarized in Table II and are reported as an increase in mean survival in percent.

TABLE II

R ¹ R ² 5 LD 50 50 * LD 50 H H 96 29 CH3 CH3 44 70 CH3 CtLCOOC.iU 52 100 ALIGN! CH3 CH 2 COOH 68 164

As can be seen from the above data, the compounds of formula I are active against A2-Hong Kong virus and EMC virus. The process for the preparation of the compounds is simple and was carried out by the process according to the invention. Further details are given in the following examples. The examples illustrate the invention but do not limit it.

Example 1

4.9-Dihydro-3-methyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

A mixture of 10 g of 3-anilino-5-methyl-4-pyrazolecarboxylic acid (50 mmol) and 75 g of polyphosphoric acid containing 85% phosphoric acid was stirred at 90 ° C for 4 hours. After addition of 350 ml of water, the reaction mixture was cooled to 5 ° C and stirred at this temperature for 1 hour. The precipitate * was aspirated and washed with water. Recrystallization from ethanol gave 8.8 g (88%) of m.p. 333 ° C to 336 ° C.

Example 2

4.9-Dihydro-1,3,9-trimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

To a solution of 2.13 g of 4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline (10 mmol) in 25 ml of dlmethylformamide was added 0.36 g of 80% hydride sodium (12 mmol) and the mixture was stirred under nitrogen at 20 ° C for 1 hour. Then, 1.69 g of methyl iodide (12 mmol) was added dropwise and the mixture was stirred at 20 ° C for 5 hours. After an additional 1.13 g of methyl iodide (8 mmol) was added, the mixture was stirred for an additional 2 hours. After addition of 50 ml of water and cooling, the precipitate was filtered off with suction and washed with water. Recrystallization from methanol gave 1.77 g (77.9%) of m.p.

223.7 ° C to 224.8 € ³ .

Example 3

4,9-Dihydro-9-ethoxycarbonylmethyl-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline *

To a suspension of 2.13 g of 4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo [(3,4-b) quinoline (10 mmol) in 50 mL of dry acetone was added. 37 g of anhydrous potassium carbonate, 0.33 g of potassium iodide and 1.67 g of ethyl bromoacetate (10 mmol) and the mixture was refluxed for 6 hours with stirring, after adding 0.84 g of ethyl bromoacetate (5 mmol) and 0.69 g of potassium carbonate was refluxed for an additional 4 hours, the cold reaction mixture was poured into 200 ml of water, the insoluble material was filtered off with suction and washed with water. 2 ° C to 215.0 ° C. Example 4

4,9-Dihydro-9-carboxymethyl-1,3-dimethyl-4-oxo-1H-pyrazolo [3,4-b] quinoline

A mixture of 1.2 g of 4,9-dihydro-9-ethoxycarbonylmethyl-4-oxo-1,3-dimethyl-1H-pyrazolo [3,4-b] quinoline (4 mmol), 24 ml of methanol and 16 ml of 1.5 The sodium hydroxide solution was stirred at 20 ^° C for 1 hour. The solution was then passed through a strongly acidic cation exchange column and washed with 50% aqueous methanol (40 g Zerolite 225 SRC 10). The column was washed with 50% aqueous methanol, the column solution was evaporated to dryness and the residue was recrystallized from methanol. 0.97 g (89.4%) of mp 218.7-220.6 ° C was obtained.

Claims (5)

SUBJECT Substituted 4,9-dihydro-3-imethyl-4-oxo-1H-pyrazolo [3,4-b] quinolines of the general formula I wherein R ¹ and R ^{2 are both} hydrogen or R ¹ and R ^{2 are both} methyl, or R ¹ is methyl and R ² is ethoxycarbonylmethyl or carboxymethyl. 2. A process for preparing a compound according to claim 1 of formula I wherein R ¹ and R ² is hydrogen, characterized in that the acid is 3-anilino-5-methyl-4-pyrazolecarboxylic acid polyfosforečnoiu heated at 80 "C to 150 ° C, preferably at 90 ° C. 3. A process for the preparation of a compound according to claim 1, wherein R @ ¹ and R @ ² are both methyl, and the method of claim 4, wherein the sodium salt is 4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo. The methyl-4-quinolimide is methyl iodide in dimethylformamide at 0 ° C to 30 ° C, preferably at 20 ° C. 4. A process for the preparation of a compound according to claim 1, wherein R < ¹ & gt ^; is methyl and R < ^{2 >} is ethoxycarbonylmethyl, characterized in that 4,9-dihydro-1,3-dimethyl-4-oxo-1H-pyrazolo [3, The 4-b] quinoline is alkylated with ethyl bromoacetate in acetone in the presence of anhydrous potassium carbonate and potassium iodide at reflux. '5. A process for the preparation of a compound according to claim 1, wherein R ¹ is methyl and R ² is carboxymethyl, characterized in that 4,9-dihydro-9-ethoxycarbonylmethyl-1,3-dimethyl-4-oxo-1H- pyrazolo [3,4-b] quinolin saponified in aqueous methanolic sodium hydroxide solution at 0 ° C to 30 ^Rc, preferably at 20 ^{° C} ° C, and the resulting sodium salt was converted to the free acid using a strongly acidic cation exchanger in acid cycle. Severography, n. P., Plant 7, Most Price 2,40 Kčs