CA1050534A

CA1050534A - Novel adenosine nitrates

Info

Publication number: CA1050534A
Application number: CA245,008A
Authority: CA
Inventors: Gunther Hausler; Ulf Fischer
Original assignee: F Hoffmann La Roche AG
Current assignee: F Hoffmann La Roche AG
Priority date: 1975-02-18
Filing date: 1976-02-04
Publication date: 1979-03-13
Also published as: ES445234A1; IE43210B1; AR217398A1; NO760520L; FI760184A; IE43210L; GB1489327A; NL7600663A; NZ179785A; JPS51105095A; HU172959B; LU74356A1; DK62776A; FR2301264B1; AU497075B2; DK136957B; FI61194B; FI61194C; DD124252A5; IL48854A

Abstract

A B S T R A C T

Adenosine nitrates of the general formula:

Description

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The present invention relates to adenosine nitrates. More particularly, the present invention is concerned with adenosine nitrates, a process for the manufacture thereof and pharmaceutical preparations contain-ing same.
The adenosine nitrates provided by the present invention are compounds of the general formula:

~ /

r(5- ~ o (1~

H~l :

;
wherein Rl and R represent a hydrogen atom or a nitro group with at least one of Rl and R2 representing a nitro group; and R5 represents a hydroxy, lower alkoxyJ amino, ~lower alkyl)amino, di-~lower alkyl)amino, [di-~lower alkyl)amino-~lower alkyl)]amino, ~nitrato-lower alkyl)amino, aryl-~lower alkyl)amino or cycloalkylamino group or a nitrogen~containing heterocyclic ring which is bonded via a nitrogen atom, and physiologically acceptable acid addition salts thereof.
In this specification, the expressions "lower alkyl" and "lower alkoxy" include straight-chain or branched-chain groups containing 1-6 carbon atoms ~e.g. methyl, methoxy, ethyl, ethoxy, propyl, propoxy, iso-propyl, isopropo~y, sec~butyl, sec.butoxy, tert.butyl and tert.butoxy).

Examples of ~lower alkyl)amino and di-~lower alkyl)amino groups are methyl-amino, ethylamino, propylamino, butylamino~ dimethylamino, diethylamino anddiisopropylamino~ Examples of aryl-~lower ~kyl)amino groups, of which the phenyl-tlower alkyl~amino groups are preferred, are the benzylamino~land 1-and 2-phenethylamino groups. The cycloalkylamino groups are especially those which contain up to 7 carbon atoms (e.g. cyclopentylamino and cyclohexylamino).
The nitrogen-containing heterocyclic ring which is bonded via a nitrogen atom .. ~ . ~, ,.

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can contain, in addition to ak Ieast one nitrogen atom, other hetero atoms such as oxygen or sulphur. 5-Membered and 6-membered heterocyclic rings are preferred. ~xamples of such rings are aziridinoJ azetidino, pyrrolidino, pyrrolo, imida~olidino, pyrazolino, thiazolino, thiazolidino, piperidino, morpholino and azepino.
Among "physiologically acceptable acid addition salts'' are salts of compounds of formula I with suitable organic or inorganic acids such as hydrochlorides, hydrobromides, sulphates, bisulphates, phosphates, ace tates, lactates, oleates 9 nitrates, mesylates, tosylates, citrates, maleates, succinates, tartrates, etc.
According to the process provided by the presen~ invention, the adenosine nitrates aforesaid (i.e. the compounds of formula I and their physiologically acceptable acid addition salts) are manufactured by nitrating - a compound of the general formula NH2 (II) H~
OH OH
wherein R5 has the significance given earlier, and, if desired, converting the product into a physiologically acceptable acid addition salt.
`~ The nitration of a compound of formula II can be carried out according to methods known ~ se.
Thus, the nitration can be carried out, for example, using nitric acid. Hydrolysis ~by water ~ormed in the reaction) or deamination (by nitrous acid which may be present) is expediently suppressed by the addition of a water-binding agent such as concentrated sulphuric acid, oleum, phosphor-us pentoxide, acetic anhydride and/or a nitrite acceptor such as urea.

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The nitration is expediently carried out at low temperatures, preferably at -30C. to 25C. and especially at -10C. to 0C.
Thcre are usually obtained mixtures of the 2'-0-nitro,3'-0-nitro and 2',3'-di-0-nitro compounds in question, which mixtures can be separated according to generally known methods (e.g. chromatography) and worked-up to give the pure compounds. It is, however, also possible to con-trol the process so that the 2~,3'-di-0-nitro compounds are isolated as the sole products, which is predominantly the case when the aforementioned water-binding agents are used.
The conversion of the compounds of formula I in~o physiolo-gically acceptable acid addition salts as well as the formation of such salts rom addition salts which are not physiologically acceptable can be carried out in the usual manner.
The compounds of formula I and their physiologically accept-able acid addition salts possess valuable effects on the heart and on the circulatory-dynamics and can accordingly be used as medicaments, inter alia, for the treatment of angina pectoris or essential hypertonia. As dosage guidelines, an amount of 0.010-30 mg/kg body weight per day can be considered.
Such dosage can be administered not only as a single dose but preferably several times daily ir divided doses.

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The coronary-dilating activity can be measured according to the following method:

Mongrels weighing between 20 and 38 kg are used for the examlnations. The test animals are narcotised with ca 30 mg/kg l.v. pentobarbital. The narcosis is maintained wlth chloralose-ureth~le. The animals are artificially respired with room-air. After opening the thorax, the hear~ is exposed and a previously calibrated flow probe of an electro magnetic flow-meter i5 placed around the Ramus circumflexus of the left coronary artery to measure the amount of blood flowlng through. The arterial blood pressure is measured via a catheter in the Artexla femoralls with a pressure transducer.
Further, a calibrated extensible measuring strip is sutured on to the surface of the left v~ntricle for the direct measurement of myocardial contraction force. The pulse wave of the blood pressure triggers a tachograph for the measurement of the heart rate. The compounds are dissolved in propyleneglycol and administered either intravenously or intraduodenally as a suspension in gum arabic. The maximum action of a substance i~;calculated in per c~nt of the starting value according to each do~age. In the measurement of the coronary blood flow, ~peclal attention is paid to the duration o~ actlon.

The results obtained are compiled in the following Table in which n signifies the number of animals used.

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5a~i34 The adenosine nitrates provided by the present invention can be used as medicaments in the form of pharmaceutical preparations, having direct or delayed release of ~he active ingredient, which contain them in association with a compatible pharmaceutical carrier material. This carrier material can be an organic or inorganlc inert carrier material suitable for enteral, percutaneous or parenteral administration sueh as, for example, water, gelatin, gum arabic, lactose, starch, magnssium stearate, talc, vegetable oils, polyalkyleneglycols, 10 petroleum jelly etc. The pharmaceutical preparation~ can be ! made up ln a solid form (e.g. as tablets, dragées, supposit-orie~ or capsules), in a 3emi-solid form (e.g. as salves) or in a liquid form (e.g. as ~olutlons, suspensions or emulslons).
The pharmaceutical preparations may be sterilised and~or may contain adjuvants such as preservatives, stabilisers, wetting agents, emulsifiers, flavour-improving agents, salts for varying the osmotic pressure or buffers. The pharmaceutical preparations can be prepared ln a manner known per se.

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The 3tarting material~ of formula II hereinbeore are known or can be prepared from known compounds in a manner known per ~e.

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The following Examples illustrate the process provided by the present inventlon:

6.7 g of urea were slowly added at -15C to 90 ml of fumlng nitric acid (d - 1.5) at such a rate that the temperature ~ dld not exceed ~10Cr To thl~ solution there were added successively at -10C 10.8 g of adenosine-5'-carboxylic acid ethyl ester. The solutlon was stirred for 3 hours in an ice-~ath, introduced lnto a mixture of 225 g of potassium ~lcar-bonate a~d 1000 g of ice-water and the precipitated crude product ~4.4. g) was flltered off under suction. By extraction of the filtrate wlth chloroform/methanol (95:5), there were obtained a urther 4.4 g of the crude product which, by chromatography on silica gel wit~h chloroform/ethyl acetate/
methanol (45:45:10), yielded the following nltroadenosines:

2.65 g of 2~,3'-dl-0-nitroade.nosine-5'-carboxylic acid ~ ethyl ester of melting point greater than 135C (decomposition) : ~rom ethyl acetate/chloroform);
0.41 g of 2~-nitroadenosine-5'-carboxy}ic acid ethyl ester of meltlng point 170-171C (decompositlon) (from ethyl acetatejdiethyl ether~; .
1.3 g of 3'-0-nitroadenosine-5'-carboxylic acid ethyl ~-ester of melting point 166.5-167C (decomposition) (from ethanol). ~ .

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100 ml of fuming nitric acid (d = 1.50) were cautiously '~:

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treated at -20C with 6.7 g of urea. 10.8 g of adenosine-5'-ethylamide were dissolved in this solution, the temperature being maintained at -20C. The mixture was subsequently stirred firstly at -20C, then slowly warmed to -5C and, after a total of 5 hours, introduced slowly into excess aqueous potassium bicarbonate solution ~230 g of potassium bicarbonate in 800 ml of wate,r). After filtering under suction and washing the precipitate with water, the filtrate wa~ extracted five times, each time with 400 ml of a mixture, of ethyl ; 10 acetate and 5% tetrahydrofuran. The organic phases were washed with saturated sodium ~-hlorLde solution, dried over magnesium sulphate and concentratefd under reduced pressure.
The total yield of crude product amounted to 11.5 g.
.

In order to separate the crude product into the 3 nitrate e~ters, it wa~ re,cry~tallised sev~sral times from ethanol, there being obtained pure 3'-0-nitroadenosin-5'-ethylamlde. 2',3'-Di-0-nitroadenosin-S'-e~hylamide could be obtained from the .~ mother }iquors by crystallisation from acetonitrile, while the complete separation of the mother liquors by chromatography on silica gel with chloroform/methanol/glacial acetlc acid (90:10~
v/v) alfo ylelded 2'-0-nitroadenosin~e,-57-carboxylic acid ethyl-am,lde.

. Th~ total yields were:
` 3.0 g (24~) of 3'-0-nitroadenosine-5'-carboxylic acid ethylamide of melting point 210C (decomposition) (from i ethanol); -2.5 g (17.8%) of 2',3'-dl~0-nitroadenosine-5'-carboxylic acid ethylamide of melting polnt 1~4C (decompo~ition) (from ace,tonitrile) and ,, ~,,' ~

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0.77 g (6.2%) of 2'-0-nitroadenosine-5'-carboxylic acid ethylamide of melting point 208C (decomposition) (rom e~hanol).

Example 3 72 ml of fuming nitxic acid were cautiously treated at ~200r with 4.9 g of urea. 6.9 g of adenosine-5'-carboxylic acid amide were slowly introduced into this solutlon, care b~lng taken that the temperature of the mixture dld not rise above -15C. The mixture was stirred for a further 5 hours while cooling to at lea~t -5C and then slowly added dropwise into ~xcess aqueous potassium bicarbonate solution (175 g of potas~ium bicarbonate in 500 ml of water), whereby a portion of the product precipltated. After filtering under suction and wa~hing with water, there were obtained 2.9 g of a mixture of 2',3'-di-0-ni~roadeno31ne-5'-carboxylic acid amlde and 3'- ~ ~
~` 0-nitroadenosine-5'-carboxylic acid amide. ~ The aqueous `
solution was extracted three times with i50 ml of chloroform a~d 5~ ethanol each tima and ~ubsequently three tlmes with 150 ml of ethyl acetate and 5~ tetrahydrofuran each tlme.
After washing with saturated sodium chloride solution and drying over magnesium sulphate, there were obtained, after concentra~ion of the chloroform~ethanol ex~ract, 2.0 g of ;~-a}most pure 2',3'-dioO-nltroadenosine-5'-carboxylic acid amide and, ~rom the ethyl acetate/tetrahydrofuran extract, 5.7 g of a m~xture of 3'-0-nitroadenosine-5'-carboxylic acid amide and 2'-0-nitroadenosine S'-carboxylic acid amlde. Repeated recrystallisation of the resldue obtained from the chloroform/
ethanol ext~act gave 1.17 g (12.8~) of pure 2',3'-di-0-nitro-, ,' ` .
,:

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.

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3~
adenosine~5'-carboxylic acid amide of meltlng point 172.5C
(decomposition). Repeated recrystallisation of the residue obtained from the ethyl acetate/~etrahydrofuran extract from ethanol/isopropanol and subsequently from methanol/water gave 2.25 g (28.1%) of 3'-0-nitroadenoslne-5'-carboxylic acid amide of melting po$nt 211C ~decomposition).
' xample 4 6.16 g of adenosine-S'-carboxylic acid dimethylamide were disf~olved at -40C in 60 ml of fuming nitr~c acid (d = 1.50).
A mixturet cooled to -20C, of 30 ml of oleum and 30 ml of nitromethane was added dropwise to this solution within 30 ¦ mlnute~ at such a rate that the temperature did not rise above i -30C. The mixture was ~tirred for 45 minutes at a temperature ;, between -30C and -25C and then poured on to a solution of 325 g of potassium bicarbonate in 1 litre of water. ~y extraction with chloroform or with chloroform contalning 5%
n propanol, there was obtained practically pure 2',3'-di-0-nltxoadenoslne-5'-carboxylic acid dimethylamide which melted at 156 5C (deoomposition) after recrysta~lisation from alcohol.
The yield was 5078 g (7~.7% of theory).
.

In an analogous manner, the followLng 2',3'-di-0-nitro-adenosines were obtained:
2',3'~di-0-nitroadenosine-SI-carboxylic acid isopropyl-amide of melting point 183C (decomposi~ion), yield 77.4%;

2',3'-di-0-nitroadenosine-5'-carboxylic acid cyclo-hexylamide of melting point 168C (decomposition), yleld G9.5%;
f 2',3'-di-0-nitroadenosine-5'-carboxylic acid ~2-(dimethyl-amino) ethyl~-amide of melting point 169C (decomposit~on) , .'~ ,:', 1 ' yield 63%j 2',3'-di-0-nitroad~nosi~e-5'-carboxylic acid [2-(2,4-dinitrophenyl~-ethyl]-amide of melting point 134C (decom position), yield 30.6%;
2',3'-di-0-nitroadenoslne-5' carboxylic acid piperidide of melting point 160C (decomposition), yield 76.2~;
2',3'-di-O~nitroadenosine-5'-carboxylic acid [2-(nitro-oxy)-ethyl]-amide of melting point 164C (decomposition), ~ yield 58.9%;
:. 10 2',3'-di-0-nitroadenosine-5'-carboxylic acid isopropyl ester of melting point 158C (decomposition), yield 71.6%.

Example 5 The reaction of 6.16 g of adenosine-5'-carboxylic acid dlmethylamide with 60 ml of fuming nitric acid and working-up in the manner descrlbed in ExampIe 4, but without the addition :o~ oleum/nitromethane t yielded a mixture o 3'-0-nitroadenosine-;. S?-carboxylic acid dimethylamide of melting point 214C (decom-po~ition), yield ~1~ of theo~y, with 2'l3'-di-0-nitroadenosine-S'-carboxylla acid dimethylamide of meltlng point 156C
. 20 (decomposi~lo~), yield 9.3% of theory.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the manufacture of adenosine nitrates of the general formula I

wherein R1 and R2 represent a hydrogen atom or a nitro group with at least one of R1 and R2 representing a nitro group; and R5 represents a hydroxy, lower alkoxy, amino, (lower alkyl)-amino, di-(lower alkyl)amino, [di-(lower alkyl)amino-(lower alkyl]amino, (nitrato-lower alkyl)amino, aryl-(lower alkyl)-amino or cycloalkylamino group or a nitrogen-containing hetero-cyclic ring which is bonded via a nitrogen atom, and physiologically acceptable acid addition salts thereof, which process comprises nitrating a compound of the general formula II

, wherein R5 has the significance given above, and, where required, converting the product into a physiologically acceptable acid addition salt.

2. A process according to claim 1, wherein in the starting material of formula II R5 represents a hydroxy group.

3. A process according to claim 1, wherein in the starting material of formula II R5 represents a lower alkoxy group.

4. A process according to claim 1, wherein in the starting material of formula II R5 represents an amino group.

5. A process according to claim 1, wherein in the starting material of formula II R5 represents a (lower alkyl)amino group.

6. A process according to claim 1, wherein in the starting material of formula II R5 represents a di-(lower alkyl)amino group.

7. A process according to claim 1, wherein in the starting material of formula II R5 represents a [di-(lower alkyl)amino-(lower alkyl)]amino group.

8. A process according to claim 1, wherein in the starting material of formula II R5 represents a [nitrato-(lower alkyl)]amino group.

9. A process according to claim 1, wherein in the starting material of formula II R5 represents a [nitrophenyl-(lower alkyl)]amino group.

10. Adenosine nitrates of the general formula I defined in claim 1, and their physiologically acceptable acid addition salts, when prepared by the process of claim 1 or by an obvious chemical equivalent thereof.