CH633014A5 - Rifamycin compounds - Google Patents

Description

633014

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CLAIMS Rifamicin compounds having formula

CH CH

* i »

wherein R is a radical selected from the group consisting of hydrogen, linear C4-Ca alkyl, C3-C8 branched alkyl, C3-C4 alkenyl, C3-C6 alkyl cycle, C7-C0 cycloalkyl-alkyl, C3-C, alkoxyalkyl, C5 -C6 alkyl-furyl, C5-C6 alkyl-tetrahydrofuryl, C5-C6 alkanoyl, C2-C6 monohalogenalkanoyl and Y is -H or COCH ,.

The present invention relates to rifamycin derivatives having high antibiotic activity.

In the patent No. 625 524 in the name of Archifar Industrie Chimiche del Trentino of which the present applicants are the successors in law, compounds obtained by reaction (I) 15 of the 3-amino-4-desoxo-4-imino-rifamycin S are described with ketones. All the compounds described in the aforementioned application are endowed with in vitro antibacterial activity on gram positive, gram negative and particularly on Mycobacterium Tuberculosis.

20 The in vivo activity assays on mice intravenously infected with Mycobacterium Tuberculosis have shown that the rifamicin derivatives obtained by reaction of 3-ami-no-4-desoxo-4-imino-rifamycin S with piperidones having general formula III.

05

(III)

(THE)

they differ from the derivatives obtained with all the other types of ketones to have a clearly superior therapeutic activity on-55 perfores. Among the derivatives of the piperidones covered by the previous patent No. 625 524, the compound obtained by reaction with N-ethyl-4-piperidone, hereinafter referred to for the sake of brevity as simply "ethyl derivative", appears to be the most therapeutically effective. The compounds described in bre-60 tip No. 625 524 were obtained by reaction with piperidones having up to 3 C atoms for R = alkyl, up to 8 C atoms for R = arylalkyl and up to 4 C atoms for R =

acyl. No other piperidones had been used because they were not accessible at the time of writing the € 5 patent application.

Recently the present applicants have been able to use other piperidones (some of which not previously described in the literature) and the derivatives with them have been found

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"33 §14

obtained have surprisingly higher therapeutic activity than those of the piperidone derivatives described in the aforementioned patent application. To highlight these differences in 'in vivo' activity, CD 1 albino mice were infected with a culture of Mycobacterium Tuberculosis H-jjRV intravenously. 0.2 ml of culture containing a double amount of LDg were injected into each mouse. After 3 days of infection, the animals were treated "orally" with rifamicin compounds at doses ranging from 20 to 1.25 mg / kg. A group of 15 mice was treated for each rifamycin compound. The treatment was carried out once a day, for 5 consecutive days every week and for a total duration of 6 weeks.

At the end of the tests, mortality was recorded and PD ^ calculated. The animals were kept under observation for about 2 months. For the "ethyl derivative" rifamycin compound the PDM was 20 mg / kg.

Activities

in vivo food

K

MIC pg / ml

PD50 mg / kg n-butyl

0.0005

5

n-hexyl

0.0005

10

allyl

0.0012

5

i-butyl

0.0012

2.6

methyl-allyl

0.005

5

sec-butyl

0.005

3.7

2-methyl-furyl

0.0012

-

1,2-dimethyl-propyl

0.005

2.5

n-pentyl

0.0012

5

1,3-dimethyl-butyl

0.0012

2.5

3-pentyl

0.0012

2.5

ethyl

0.01

20

Table I where the results obtained in these experiments with «ethyderivate» and with some of the new compounds are collected shows that the new derivatives having general formula I where R is a radical chosen from the group consisting of linear C4-Cg alkyl, C3-C8 branched alkyl, C3-C4 alkenyl, C3-C6 cycloalkyl, C7-Cß cycloalkyl-alkyl, C3-C7 alkoxyalkias, C5-C6 alkylfuryl, C5-C6 alkyl-tetrahydrofuryl, C5-C6 alkanoyl, C2-C6 monohalogen and Y is -H or COCHj, have a surprisingly lower PD ^ and are therefore more effective than ethyl derivative and therefore of all the compounds covered by patent No. 625 524.

Some non-limiting examples of the claimed invention will now be described.

Example 1

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of dichloromethane and allowed to react with 2.6 g of l-n-hexyl-4-piperidone at + 5 ° C for 48 hours. The solution is then diluted with 600 ml of ethyl ether, filtered and washed with water. The organic phase is dried over sodium sulphate and then evaporated to dryness.

The residue is extracted with ligroin and the purple solution is evaporated to dryness.

Yield: 2.5 g of a product of formula (I), wherein Y is -COCHj, and R is n-hexyl. The electronic absorption spectrum in methanol shows maximums at 497,314,278 and 238 nm.

Operating with the same method but using 1-n-penu-4-pidperidone, a compound of formula (I) is obtained in which Y is -COCHj and R is n-pentyl. The electronic absorption spectrum in methanol shows maximums at 500.316, 278 and 240 nm.

Example 2

8 g of 3-amino-4-deoxy-4-imyno-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 4 g of 1,1- (1,3'-di-methyl) -butyl-4 -peridone, 0.5 g of zinc, 0.5 g of ammonium acetate are added and the mixture is kept under stirring for 30 '. The reaction product is isolated with the method described in the previous example.

Yield: 3.5 g of a product of formula (I) wherein Y is -COCHj and R is 1.3-dimethyl-butyl.

The electronic absorption spectrum in methanol shows maximums at 500,315,277 and 240 nm.

Operating with the same method but using 1- (1 '- ethyl) -propiI-4-piperidone a product of formula (I) is obtained in which Y is -COCHj and R is 3-pentyl.

The electronic absorption spectrum in methanol shows maximums at 500, 315, 276 and 240 nm.

Example 3

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 1.8 g of 1-methyl allyl-4-piperidone, 0.2 g of zinc, 0.2 g of ammonium acetate are added and the mixture is left to rest overnight at + 5 ° C.

The reaction product is isolated with the method described in example 1.

Yield: 5.5 g of a product of formula (I) wherein Y is -COCHj and R is metal. The electronic absorption spectrum in methanol shows maximums at 498, 313, 275 and 238 nm.

By operating with the same method but using l-allyl-4-piperidone, a product of formula (I) is obtained in which Y is -COCH3 and R is aityl. The electronic absorption spectrum in methanol shows maximums at 491, 314, 276 and 235 nm.

Example 4

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 3 g of 1-cyclohexyl-4-piperidone, 0.2 g of zinc, 0.2 g of ammonium acetate are added and the mixture is stirred for 2.5 hours at room temperature.

The unreacted zinc is filtered and the solution is diluted with 1000 ml of ethyl ether. The ethereal solution is washed with sodium phosphate buffer solution at pH 7.8 and then extracted with diluted acetic acid. The purple acetic solution is extracted with chloroform and the chloroform phase, washed with water and dried over sodium sulphate, is evaporated to dry.

Yield: 3.8 g of a product of formula (I) wherein Y is -COCHj and R is cyclohexyl. The electronic absorption spectrum in methanol shows maximums at 498, 312, 273 and 235 nm.

Example 5

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 0.5 g of zinc, 0.5 g of ammonium acetate, 5.5 g of l- (methyl-furyl) - 4-piperidone are added and the mixture is stirred for 24 hours at room temperature. The reaction mixture is filtered, diluted with 500 ml of ethyl ether and washed with water. The organic phase is concentrated to 250 ml and then extracted with diluted acetic acid. The aqueous acid phase is extracted with dichloromethane and the latter, after washing with water, is dried over sodium sulphate and evaporated to dryness.

s

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1S

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633014

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Yield: 3.3 g of a product of formula (I), wherein Y is -COCHj and R is methyl furyl. The electronic absorption spectrum in methanol shows maximums at 497, 316, 276 and 240 nm.

By operating with the same method but using 1-n-butyl-4-piperidone, a product of formula (I) is obtained in which Y is -COCH3 and R is n-butyl. The electronic absorption spectrum in methanol shows maximums at 496, 317, 276 and 240 nm.

Similarly, the products of formula (I) are obtained wherein Y is -COCH3 and R is i-butyl and sec-butyl.

For R = i-butyl the electronic absorption spectrum in methanol shows maxima at 493, 315, 274 and 238 nm.

For R = sec-butyl the maximums are at 500, 315, 275 and 240 nm.

Example 6

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran and dropped at 50 ° C in a mixture of 15 ml of tetrahydrofuran, 5 ml of acetic acid, 1 g of zinc and 5 g of l- (methyl-tetrahydrofuril) -4-piperidone. The reaction product is continued to be heated at 50 ° C for 30 'and then the reaction product is isolated following the method described in example 5.

Yield: 2.1 g of a product of formula (I) wherein Y is -COCHj and R is methyl-tetrahydrofuryl. The electronic absorption spectrum in methanol shows maximums at 495, 314, 275 and 239 nm.

Operating with the same method but using 1- (1 ', 2' - dimethyl) -propyl-4-piperidone, a product of formula (I) is obtained in which Y is -COCH3 and R is 1,2-dimethyl-propyl . The electronic absorption spectrum in methanol shows maximums at 498, 315, 277 and 240 nm.

Example 7

32 g of 3-amino-4-deoxy-4-imino-rifacimin S are dissolved in 200 ml of tetrahydrofuran. 9 g of 4-piperidone monohydrate hydrochloride, 10 g of ammonium acetate, 0.4 g of zinc are added and the mixture is stirred at room temperature for 12 hours. The reaction mixture is filtered and the filtrate is dropped into 1500 ml of diluted acetic acid. It is filtered again, neutralized to pH 6 with sodium bicarbonate and then extracted with dichloromethane.

Yield: 13.4 g of a product of formula (I) wherein Y is -COCH, and R is hydrogen. The electronic absorption spectrum in methanol shows maximums at 500, 315, 275 and 240 nm.

Example 8

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 50 ml of tetrahydrofuran. 0.3 g of zinc, 0.3 g of ammonium acetate, 2.5 g of 1-chloroacetyl-4 - piperidoner are added and the mixture is left to rest for 48 hours at + 5 ° C. The filtrate is filtered, diluted with 150 ml of dichloromethane and 800 ml of cyclohexane. It is filtered again, washed with sodium phosphate buffer solution at pH 7.5 and then with water. The solvent is evaporated and the residue is crystallized from cyclohexane.

Yield: 3.2 g of a product of formula (I) of which Y is -COCHj and R is chloroacetyl. The electronic absorption spectrum in methanol shows maximums at 497, 310, 273 and 235 nm.

Example 9

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 0.5 g of zinc, 5 ml of acetic acid, 4.5 g of 1-n-octyl-4-piperidone are added and the mixture is stirred for 10 'at room temperature. The unreacted zinc is filtered and the filtrate is diluted with 700 ml of diisopropyl ether. It is filtered again and concentrated in vacuo up to 300 ml. 300 ml of petroleum ether are added and filtered again. The solvent is evaporated and the oily residue, dissolved in 40 ml of methanol, is dripped in 400 ml of water. The precipitate obtained is filtered, washed with water and dried at 40 ° C under vacuum.

Yield: 3.8 g of a product of formula (I), wherein Y is -COCH3 and R is n-octyl. The electronic absorption spectrum in methanol shows maximums at 497, 310, 274 and 236 nm.

Example 10

16 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 100 ml of tetrahydrofuran. 1 g of zinc, 0.5 g of ammonium acetate, 8 g of l- (3'-methoxy) - propyl-4-piperidone are added and the mixture is stirred at room temperature for 60 '. The reaction mixture is filtered, diluted with 1500 ml of xylene and washed with water. The organic phase is extracted with diluted and then dried acetic acid. The aqueous solution, neutralized to pH 7 with dibasic sodium phosphate is extracted with dichloromethane. After dilution with petroleum ether it is filtered and the resulting purple solution is evaporated to dryness.

Yield: 3.0 g of a product of formula (I) wherein Y is -COCH3 and R is methoxy-propyl. Thin layer chromatography of silica gel shows a violet spot with Rf = 0.48 using the 9: 1 chloroform-methanol mixture as a mobile phase.

Example 11

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 40 ml of tetrahydrofuran. 0.5 g of zinc, 0.5 g of ammonium acetate, 4.5 g of l- (l ', 4'-dimethyl) - pentyl-4-piperidone are added and the mixture is stirred at room temperature for 30 '. THE

The reaction product is isolated following the method described in example 10.

Yield: 5.0 g of a product of formula (I) wherein Y is -COCH3 and R is 1.4-dimethyl-pentyl. Thin layer chromatography of silica gel shows a purple spot with Rf = 0.52 using the chloroform-methanol 9: 1 mixture as a mobile phase.

Example 12

8 g of 3-amino-4-deoxy-4-imino-rifamycin S are dissolved in 50 ml of tetrahydrofuran. 0.2 g of zinc, 0.2 g of ammonium acetate, 3 g of l-pivaloil-4-pipe-ridone are added and the mixture is left to rest at 0 ° C for 3 days.

The reaction mixture is filtered, the filtrate is diluted with 300 ml of ethyl ether and washed with sodium phosphate buffer at pH 7.5. The organic phase is washed with water, dried over sodium sulphate and evaporated to dry. The residue is crystallized of cyclohexane.

Yield: 7 g of a product of formula (I) in which Y is -COCH3 and R is pivaloid. The electronic absorption spectrum in methanol shows maximums at 497, 316, 276 and 238 nm.

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