CS240738B1 - 3-alkyl-2-pyrazinecarboxylic acid derivatives - Google Patents

Abstract

The solution relates to derivatives of 3-alkyl-2-pyrazinecarboxylic acid of the general formula 2 R represents an amide group —CONH2, a thioamide group —CSNH2 or a hydrazide group —CONHNH2 and A represents isopropyl, butyl, isobutyl and in the case that R represents a thioamide or hydrazide group, A also represents methyl, ethyl and propyl. The above compounds show biological activity mainly against acid-resistant microorganisms, especially against Mycobacterium tuberculosis and also against atypical strains of mycobacteria and can serve as starting materials for the production of, for example, antituberculosis drugs.

Description

The invention relates to 3-alkyl-2-pyrazinecarboxylic acid derivatives of the general formula

R group amide — CONH ₂ , thioamide — CSNH ₂ or hydrazide —CONHNH ₂ and

A is isopropyl, butyl, isobutyl and, when R represents a thioamide or hydrazide group, A also represents methyl, ethyl and propyl.

These compounds exhibit significant biological activity, particularly against acid-fast microorganisms, especially against Mycobacterium tuberculosis and also against atypical strains of mycobacteria.

The interest in functional derivatives of 3-alkyl-2-pyrazinecarboxylic acid was aroused by the practical use of effective antituberculosis drugs from the group of thioamides, for example ethionamide, prothionamide Libermann D., Moyeux M., Rist N., Grumbach F.: Compt. und. 242, 2409 (1956); Brit. pat. 860, 250 (1958) and hydrazides, mainly isoniazid Fox Η. H.: J. Org. Chem. 17, 542, 547, 555 (1952); Bernstein J., Lott W. A., Steinberg B. A., Yale H. L.: Am. Rev. Tuberc. 65, 365 (1977) and from the pyrazinamide group.

Biological activity was investigated for the following substances:

T 163 3-methyl-2-pyrazinecarboxylic acid hydrazide

T 164 hydrazide of 3-ethyl-2-pyrazine-carboxylic acid

T 410 3-propyl-2-pyrazinecarboxylic acid hydrazide

T 411 3-isopropyl-2-pyrazinecarboxylic acid hydrazide

T 412 3-butyl-2-pyrazinecarboxylic acid hydrazide

T 413 3-isobutyl-2-pyrazinecarboxylic acid hydrazide

T 401 3-isopropyl-2-pyrazinecarboxylic acid amide

T 402 3-butyl-2-pyrazinecarboxylic acid amide

T 403 3-isobutyl-2-pyrazinecarboxylic acid amide

T 170 3-methyl-2-pyrazinecarboxylic acid thioamide

T 420 3-ethyl-2-pyrazinecarboxylic acid thioamide

T 421 3-propyl-2-pyrazinecarboxylic acid thioamide

T 422 3-isopropyl-2-pyrazinecarboxylic acid thioamide

T 423 3-butyl-2-pyrazinecarboxylic acid thioamide

T 424 3-isobutyl-2-pyrazinecarboxylic acid thioamide

T 172 3-methyl-2-pyrazinecarboxylic acid amide

T 171 3-ethyl-2-pyrazinecarboxylic acid amide

T 400 3-propyl-2-pyrazinecarboxylic acid amide

The microbiological evaluation of the tested substances is shown in Table 1. All substances were tested in vitro for their activity against Mycobacterium tuberculosis H ₃₇ Rv, Mycobacterium kansasii PKG 8, Mycobacterium aviurn 16/8 and Mycobacterium fortuitum on liquid Šul's soil at pH 5.4 in comparison with pyrazinamide as a standard. The results according to Table 1 show that some substances show significant activity, in which they even surpass the effectiveness of the standard. This applies primarily to substance T 421, which is active at a concentration of 5 µg/ml against M. tuberculosis H ₃₇ Rv and at concentrations of 10 µg/ml against other Mycobacteria. Substance T 170 is active at a concentration of 10 µg/ml against other strains. Higher activity against atypical strains. Substance T 422 also showed higher activity against Mycobacteria. The minimum inhibitory concentrations of the tested substances are shown in the following Table 1.

Table 1

Compound Mycobacterium tuberculosis H ₃₇ Rv Mycobacterium kansasii PKG 8 Mycobacterium avium 16/8 Mycobacterium fortuitum T 163 50 >400 >400 >400 T 164 >400 >400 >400 >400 T 410 200 400 400 400 T 411 400 400 400 400 T 412 400 400 400 400 T 413 400 400 400 400 T 401 400 400 400 . 400 T 402 200 400 400 400 T 403 200 400 400 400 T 170 <12.5 <12.5 <12.5 25 T 420 25 200 200 200 T 421 5 10 10 10 T 422 25 100 100 100 T 423 100 200 400 400 T 424 50 200 200 400 T 172 100 400 >400 >400 T 171 >400 >400 >400 >400 T 400 200 400 400 400 Explanation: all concentration values are given in /xg/ml.

The following examples of embodiments of the substance according to the invention illustrate, but are not limiting in any way.

Example

Preparation of 3-alkyl-2-pyrazinecarboxylic acid amide

48.6 g of magnesium shavings were poured over 100 ml of anhydrous ethyl alcohol and 10 ml of anhydrous carbon tetrachloride was added, which initiates the formation of magnesium ethylate. After the reaction, a solution of 260 g (2 mol) of ethyl acetoacetate, 200 ml of anhydrous corresponding alkyl alcohol and 800 ml of

Table 2

Compound T. v.

(A) (°C/kPa) of anhydrous ether. After the magnesium was dissolved, a solution of the appropriate acyl chloride (2 mol) and 200 ml of anhydrous ether were added dropwise while cooling. The reaction mixture was left to stand at room temperature overnight. Then, 800 g of ice and 50 ml of concentrated sulfuric acid were added to the reaction mixture while cooling. The resulting ether layer was separated and the aqueous layer was extracted twice with 150 ml of ether. The combined ether extracts were washed with water and dried with anhydrous sodium sulfate. After distilling off the ether, the product obtained was vacuum distilled. The obtained ethyl α-acylacetoacetates (A) are given in Table 2.

T. v. Yield (°C/kPa lit. ¹ ) (%)

α-propionylacetoacetate ethyl- 105 to 107/1.6 111/2.7 95.7 th «-Ethyl butyrylacetoacetate 112 to 114/2.1 112/2.1 90.0 a-isobutyrylacetoacetate ethyl 113 to 114/2.0 114/2.0 89.5 ethyl oj-valerylacetoacetate 118 to 119/1.6 119/1.7 95.0 Ethyl α-isovalerylacetoacetate 117 to 118/1.6 118/1.6' 89

A mixture of 1 mol of the corresponding ethyl acylacetoacetate (A) with a solution of 1.05 mol of potassium hydroxide in 500 ml of ethyl alcohol was left to stand overnight at room temperature. The reaction mixture was then poured onto 3 kg of crushed ice with 27 ml of concentrated sulfuric acid and extracted with 4 x 200 milliliters of ether. The combined ether extracts were washed with water until neutral and dried over anhydrous sodium sulfate. After distilling off the solvent, the residue was vacuum distilled. The ethyl acylacetoacetates (B) obtained are given in Table 3.

Table 3

Compound (B) T. v, (°C/kPa] T. v. ^ut ·) (°C/kPa] Yield (%) ethyl propionylethane 90 to 92/2.3 91 to 92/2.3 ² 67 ethyl butyryloctane 98 to 100/2.3 94 to 96/2.0 ² 69 ethyl isobutyrylacetate 76 to 77/2.0 76 to 78/2.0 ³ 71 ethyl valerethyl acetate 113 to 115/2.1 110 to 112/2.1 ⁴ 66 ethyl isovaleryl ethane 98 to 100/2.0 97 to 99/1.9 ⁴ 68 1 mole of the corresponding acylacetate ethyl- then it was diluted with about 300 ml of cold water- it (B) was dissolved in 400 ml glacial acid- dy. The obtained oily product was extracted acetic acid. The solution was added in small bath 3 >; 100 ml ether. Ethernet layer 450 g (1 mol] added in batches acetate g- was washed with approximately 50 ml of 10% hydrogen peroxide solution of the falcon, the temperature of the solution was maintained sodium carbonate, 100 ml of water and below 45 °C. The reaction was terminated by heating dried with sodium sulfate. The obtained α-aoethoxy- reaction mixtures at 70 °C for 30 minutes, -ethyl acylacetates (C) given in Table 4. Table 4 Compound T. v. T. v. ^Ht · Profit (°C/kPa) (°C/kPa) ('% J ια-acetoxy-acetoacetate ethyl 119 to 121/2.0 120 to 122/2.0 ⁵ 80 . •a-acetoxy-propionylacetate ethyl 127 to 128/1.9 — 79 «-acetoxy-butyryloctane _Λ ethyl 132 to 133/1.8 — 78 •a-acetoxy-isobutyrylethane ethyl 132 to 132/1.7 — 74 a-acetoxy-valerylacetate ethyl 137 to 138/1.7 — 71 tf-acetoxy-isovaleryl acetate ethyl 134 to 135/1.6 — 72 0.7 mol of the corresponding α-acetoxy-acetoxy-acetoxy removed hydrogen chloride and after distillation ethyl (C) was dissolved in 400 ml the solvent residue was vacuum-filtered 0.5 mol of hydrochloric acid in ethyl alcohol lovant. Obtained « hydroxy-acyloactates ethyl- alcohol. The reaction mixture was left at room temperature for then (D) is given in Table 5. for 18 h, then was purged with nitrogen Table 5 Compound T. v. T. v. ^nt · Profit (Dj (°C/kPa) (°C/kPa) (%) and ethyl hydroxy-acetoacetate 94 to 95/1.3 93 to 94/1.3 ⁶ 80 a-hydroxy-propionylacetate ethyl 98 to 99/1.4 — 79 -α-hydroxy-butyryloctane ethyl 107 to 109/1.5 — 79 a-hydroxy-isobutyrylacetate ethyl 113 to 115/1.4 — 78 a-hydroxy-valerylacetate ethyl 119 to 121/1.4 — 75 a-hydroxy-isovaleryl acetate ethyl 126 to 128/1.5 — 74

0.24 mol of the corresponding ethyl α-hydroxy=acyloacetate (Dj) was dissolved in 500 milliliters of ethyl alcohol. 19 g (0.17 mol] of selenium dioxide was added to the solution and the reaction mixture was stirred intensively for 6 h. The formed metallic selenium was filtered off and the reaction mixture was refluxed for 6 h. The formed selenium was filtered off again and after distilling off the solvent, the residue was vacuum distilled. The obtained ethyl esters of α,/J-dioxocarboxylic acids (E) are given in Table 6.

Table 6

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Compound (E) Temperature (°C/kPa) T. v. ^nt · (°C/kPa) Yield (%) ethyl ester of «'jS-dioxobutanecarboxylic acid 66 to 67/1.5 66/1.5 ⁶ 80 ethyl ester of,(S'-dioxopentanecarboxylic acid 79 to 80/1.35 78 to 80/1.3 ⁷ 79 ethyl ester of 1,1/3-dioxohexanecarboxylic acid 85 to 86/1.6 87 to 88/1.7 ⁷ 76 α,/ϊ-dioxoisohexanecarboxylic acid ethyl ester 84 to 85/1.6 74 «,ι,β-dioxoheptanecarboxylic acid ethyl ester 121 to 122/2.1 120 to 125/2.0 ⁸ 76 •α,/?-dioxoisoheptanecarboxylic acid ethyl ester 199 to 122/2.1 — 71 A solution of 0.35 mol of the respective ethyl ester 18 h was the mixture boiled under reflux- «,/J-dioxocarboxylic acids in 1000 ml of something. After filtering the reaction mixture was from

of benzene was added dropwise with vigorous stirring to a boiling solution of 21 g (0.35 mol) of ethylenediamine in 1,250 ml of benzene. The water formed during this condensation reaction was collected in a Dean-Stark tube and the reaction was monitored by chromatography. As soon as water ceased to be formed, the reaction mixture was cooled, 7.5 g of 10% palladium on activated carbon catalyst were added and the solvent was distilled off from the filtrate under reduced pressure and the residue was extracted with 100 ml of boiling petroleum ether (b. v. 60 to 70 °C). The electrolyte obtained was cooled to 5 °C for 2 h and filtered. The filtrate was concentrated by distillation and allowed to crystallize. The crude product was recrystallized from petroleum ether. The ethyl esters of 3-alkyl-2-pyrazinecarboxylic acids obtained (FJ are given in Table 7.

Table 7 Compound T. t. (F) (°C) 3-methyl-2-pyrazinecarboxylic acid ethyl ester 51 to 52 3-ethyl-2-pyrazinecarboxylic acid ethyl ester 54 to 55 3-propyl-2-pyrazinecarboxylic acid ethyl ester 58 to 59 3-isopropyl-2-pyrazinecarboxylic acid ethyl ester 57 to 58 3-butyl-2-pyrazinecarboxylic acid ethyl ester 61 to 62 3-isobutyl-2-pyrazinecarboxylic acid ethyl ester 60 to 61

0.1 mol of the corresponding ester (FJ) was dissolved in 25 ml of ethanol and 300 ml of 25% aqueous ammonia solution was added. The reaction mixture was left at room temperature for 3 days. T. t. ^Ut · Yield

Í°C) (%) to 52 ⁹ 32 — 33 — 31 — 29 — 29 — 30 ti. Then the solution was evaporated to dryness in vacuo and the residue was crystallized from ethanol. The obtained 3-alkyl-2-pyrazinecarboxylic acid amides (G) are given in Table 8.

Table 8

Compound (G) Code M. t. (°C) T. t. ^Ht ( ^p C) Yield (%) 3-isopropyl-2-pyrazinecarboxylic acid amide T 401 95 to 96 54 3-butyl-2-pyrazinecarboxylic acid amide T 402 68 to 69 56 3-isobutyl-2-pyrazinecarboxylic acid amide T 403 63 to 64 — 57 3-methyl-2-pyrazinecarboxylic acid amide T 172 165 to 166 164 to 165 ¹⁰ 65 3-ethyl-2-pyrazinecarboxylic acid amide T 171 120 to 121 119 to 12Ο ¹⁰ 58 3-propyl-2-pyrazinecarboxylic acid amide T 400 98 to 99 98 to 99 ¹⁰ 61

The known amides T 171, T 172, T 400 listed below are listed for completeness only. Example 2

Preparation of 3-alkyl-2-pyrazinecarboxylic acid thioamides

0.04 mol of the corresponding amide (G), prepared according to Example 1, was suspended in 400 ml of anhydrous benzene and 72 ml of phosphoryl chloride was added. The reaction mixture was heated for 2.5 h at a temperature of 80 to 90 degrees Celsius. Then, benzene and phosphoryl chloride were distilled off under vacuum, ice was added to the residue and the solution was neutralized with 10% sodium carbonate solution. The reaction mixture was extracted with chloroform and after distilling off the solvent, the residue was distilled under vacuum. The obtained 3-alkyl-2-pyrazinecarboxylic acid nitriles (H) are given in Table 9.

Table 9

Compound T. v. T. v. ¹ ' ¹ · Profit (H) (°C/kPa) (°C/kPa) (%) 3-methyl- nitrile -2-pyrazinecarboxylic 93 to 94/1.9 125 to 126/6.7 ¹⁰ 75 3-ethyl nitrile -2-pyrazinecarboxylic 101 to 102/1.9 102 to 103/2.0 ¹ ° 73 3-propyl nitrile -2-pyrazinecarboxylic 114 to 115/2.1 112 to 113/2.0 ¹⁰ 71 3-isopropyl- nitrile -2-pyrazinecarboxylic 108 to 109/2.0 — 69 3-butyl nitrile -2-pyrazinecarboxylic 125 to 126/2.1 — 72 3-isobutyl nitrile -2-pyrazinecarboxylic 122 to 123/2.1 — 68 0.44 moles of the corresponding nitrile (H) was divided- distilled solvents and the residue was dissolved in 22 ml of anhydrous pyridine and 16 crystallized from ethanol. Thioamides obtained

ml of anhydrous triethylamine. The reaction mixture was saturated with dry hydrogen sulfide for 2 h with cooling. Under reduced pressure,

3-alkyl-2-pyrazinecarboxylic acids (CH) are given in Table 10.

Table 10

Compound Code T. t. Profit (GH) (°C) (%) 3-methyl-thioamide -2-pyrazinecarboxylic T 170 147 to 148 78 3-ethyl-thioamide -2-pyrazinecarboxylic T 420 134 to 135 79 3-propyl-thioamide -2-pyrazinecarboxylic T 421 124 to 126 76 3-isopropyl-acid thioamide -2-pyrazinecarboxylic T 422 121 to 122 75 3-butyl-thioamide -2-pyrazinecarboxylic acid . T 423 111 to 112 76 3-isobutyl-acid thioamide -2-pyrazinecarboxylic T 424 104 to 105 71 Example 3 15 ml of ethanol and 2.6 was added to the solution grams of 80% hydrazine hydrate. Reaction mixture Preparation of 3-alkyl-2-pyrazinecar- hydrazides was cooked under reflux refrigerator 17 h. boxyl acids. Then there was the solvent distilled for vacuum and the residue was crystallized from ethanol- 0.01 mole of the corresponding amide (G), prepared lu. The obtained hydrazides of 3-alkyl-2-pyrazinecar- prepared according to Example 1, was dissolved in boxylic acids (K) are given in Table 11. Table 11 Compound Code T. t. Profit (K) (°C) (%) 3-methyl-acid hydrazide -2-pyrazinecarboxylic T 163 114 to 116 56 3-ethyl-acid hydrazide -2-pyrazinecarboxylic T 164 104 to 106 58 3-propyl hydrazide -2-pyrazinecarboxylic T 410 80 to 81 57 3-isopropyl-hydrazide • -2-pyrazinecarboxylic T 411 77 to 78 55 3-butyl hydrazide -2-pyrazinecarboxylic T 412 69 to 70 57 3-isobutyl-hydrazide -2-pyrazinecarboxylic T 413 64 to 66. 57

Note on the examples: For all new compounds, elemental analysis was also performed for identification, which in all cases was in full agreement with the calculated theoretical values.

Claims (1)

SUBJECT 3-Alkyl-2-pyrazinecarboxylic acid derivatives of the general formula VYNALEZU R is amide-CONH ₂ , thioamide-CSNH ₂ or hydrazide-CONHNH ₂ and A isopropyl, butyl, isobutyl, and when R is a thioamide or hydrazide group, A is also methyl, ethyl and propyl. in which it denotes