CA1138470A - Citric acid derivatives - Google Patents
Citric acid derivativesInfo
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- CA1138470A CA1138470A CA000342235A CA342235A CA1138470A CA 1138470 A CA1138470 A CA 1138470A CA 000342235 A CA000342235 A CA 000342235A CA 342235 A CA342235 A CA 342235A CA 1138470 A CA1138470 A CA 1138470A
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- Prior art keywords
- acid
- threo
- chlorocitric
- erythro
- formula
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-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D305/00—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms
- C07D305/02—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms not condensed with other rings
- C07D305/10—Heterocyclic compounds containing four-membered rings having one oxygen atom as the only ring hetero atoms not condensed with other rings having one or more double bonds between ring members or between ring members and non-ring members
- C07D305/12—Beta-lactones
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/09—Preparation of carboxylic acids or their salts, halides or anhydrides from carboxylic acid esters or lactones
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/347—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups
- C07C51/363—Preparation of carboxylic acids or their salts, halides or anhydrides by reactions not involving formation of carboxyl groups by introduction of halogen; by substitution of halogen atoms by other halogen atoms
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C59/00—Compounds having carboxyl groups bound to acyclic carbon atoms and containing any of the groups OH, O—metal, —CHO, keto, ether, groups, groups, or groups
- C07C59/235—Saturated compounds containing more than one carboxyl group
- C07C59/245—Saturated compounds containing more than one carboxyl group containing hydroxy or O-metal groups
- C07C59/295—Saturated compounds containing more than one carboxyl group containing hydroxy or O-metal groups containing halogen
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07D—HETEROCYCLIC COMPOUNDS
- C07D303/00—Compounds containing three-membered rings having one oxygen atom as the only ring hetero atom
- C07D303/02—Compounds containing oxirane rings
- C07D303/48—Compounds containing oxirane rings with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, directly attached to ring carbon atoms, e.g. ester or nitrile radicals
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Epoxy Compounds (AREA)
- Pharmaceuticals Containing Other Organic And Inorganic Compounds (AREA)
- Acyclic And Carbocyclic Compounds In Medicinal Compositions (AREA)
Abstract
Abstract Citric acid derivatives of the formula Ia and corresponding threo-.beta.-lactones of the formula
Description
- ~ 3~
The present invention relates to novel citric acid derivatives of the formula H ~ ~ CO2H
~CI la ~ OH
H02C/ ~cH2co2H
and corresponding threo-~-lactones of the formula HO2C ` H
< Cl lb ~
as well as pharmaceutically acceptable salts of these compounds.
The chlorocitric acids of formula Ia and certain star-ting materials and intermediates in the preparation there-of, bear two asymmetric centers and thus exist in two relative stereochemical forms: a threo form and an erythro 25 form. The chlorocitric acid-~-lactones of formula Ib have the threo form. Each form, i.e. the threo form and erythro form, can exist as a racemate and two optical antipodes, the (+)-optical antipode and the (-)-optical antipode.
In conjunction therewith, the threo-erythro nomenclature 30 as defined in J. Amer. Chem. Soc., 74, 5828 (1952) and Experientia, 12, 81 (1956) has been adopted.
Mé/5.11.1979 ~"3!~47~
As used throughout the specification and appended claims, the term "alkali metal" and "alkaline earth me-tal" refer to lithium, sodium and potassium, and calcium, respectively. The term "alkanol" refers to the compound 5 derived by replacement of a proton of a straight or branched chain alkane having 1 to 20 carbon atoms by a hydroxyl moiety. Examples of alkanols include methanol, ethanol and 2-propanol.
The compounds of ~ormulae Ia and Ib and the salts thereof exhibit anorectic activity and are thus useful as anorectic agents for the treatment of obesity in mam-mals. The invention relates to the compounds of formulae Ia and Ib and the pharmaceutically acceptable salts there-15 Of as pharmaceutical, particularly anorectic, agents,as well as to pharmaceutical compositions, particularly anorectic compositions, comprising a compound of formula Ia or Ib or a pharmaceutically acceptable salt thereof, and to a process for the manufacture of such compositions.
The invention also relates to a process for the manu-facture of the compounds of formulae Ia and Ib and of the pharmaceutically acceptable salts thereof, which pro-cess comprises a) for the preparation of a (+)-threo-lactone of formula Ib contacting an aqueous solution of a tri-alkali metal salt or tri-alkaline earth metal salt of cis- or trans-aconitic acid with chlorine or hypochlorous acid 30 and contacting the obtained salt of (~)-threo-chlorocitric acid-R-lactone of the formula ~ -" ' ' . ' ' . , ' ' 1~.3B470 \<CI I b 1 M02C <~co wherein M is an alkali or alkaline earth metal, with an acid, b) for the preparation of (+)-threo-chlorocitric acid of the formula ~ OCH lla 1 20 hydrolyzing a compound of formula Ib or Ib1, c) for the preparation of a compound of formula Ia clea-ving epoxyaconitic acid with an alkali metal chloride or alkaline earth metal chloride in an aqueous solvent 25 in the presence of an acid, d) for the preparation of (+)-erythro-chlorocitric acid of the formula ~ ~Cl la2 ~OH
H 02C/ \CH2C 2 H
35 cleaving an epoxide of the formula 1~3~4';'~
M~02C H
wherein M' is an alkali metal and R is hydrogen or M', 10 with in alkali metal chloride in an aqueous solvent in the presence of an acid, e) if desired, resolving an obtained (+)-threorcitric acid derivative of formula Ia or Ib or (+)-erythro-citric acid derivative 15 of formula Ia into its optically active antipodes and isolating a desired antipode, f) if desiredlisolating an obtained compound of formula Ia or Ib in form of a pharmaceutically àcceptable salt 20 thereof.
The aqueous solution of process step a), which can be obtained by dissolving aconitic acid in an aqueous solution of an alkali or alkaline earth metal hydroxide, 25 preferably sodium or potassium hydroxide, is conveniently cooled to about 0 to 30C, preferably 5C, and treated with excess chlorine or hypochlorous acid, preferably chlorine.
Suitable aqueous solvents include water and mixtures of water and a lower alkanol, water and an ether, such as dimethoxyethane, tetrahydrofuran or dioxane, and water - and a polar aprotic solvent, such as dimethylacetamide, dimethylformamide, dimethylsul~oxide or hexamethylphos-35 phoramide.
Among acids suitable for the conversion of the salt ,. ..
~8~
Ib1 to the corresponding free acid Ib may be mentioned mineral acids, e.g. hydrochloric, sulfuric, nitric or phosphoric acid, sulfonic acids, such as methanesulfonic, phenylsulfonic or p-toluenesulfonic acid, and strong orga-nic carboxylic ~cids, such as trifluoro- or trichloroace-tic acid.
The hydrolysis of the ~-lactone function of the di-acid of formula Ib or the disalt thereof of formula Ib1 10 according to process step b), can be accomplished by sus-pending or dissolving the diacid or the disalt in an aqueous solvent containing an acid, such as those employed for the acidification of the disalt Ib1 to the diacid Ib, ard heating the resulting reaction system, conveniently 15 at a-temperature of about 30 to 80C to complete the hydrolysis. A temperature of about 50 to 70C, particu-larly of about 70C, is preferred.
While the chlorohydrination of step a) and the hy-20 drolysis of step b) may be performed stepwise, it is moreconvenient and efficient to acidify the disalt Ib1 and heat the resulting reaction mixture to complete the hy-drolysis of the diacid Ib to afford (+)-threo-chlorocitric acid. Thus, upon completion of the chlorohydrination, 25 the reaction mixture is acidified, preferably with a mineral acid, most preferably hydrochloric acid, and heated from about 30 to 100C, preferably from about 50 to 90C, most preferably at about 70C, to complete the conversion of the B-lactone Ib to the acid Ia1.
The cleavage of step c) is carried out with an al-kali or alkaline earth metal chloride in an aqueous sol-vent in the presence of an acid.
Thus (+)-threo-epoxyaconitic acid may be cleaved by an alkali metal chloride dissolved in an aqueous solvent in the presence of an acid, preferably by excess sodium ~3~
chloride dissolved in water in the presence of one molar equivalent of hydrochloric acid at a temperature within the range of about 50 to 80C, most preferably at about Likewise, (+)-threo-epoxyaconitic acid is cleaved to (-)-threo-chlorocitric acid, (-)-threo-epoxyaconitic acid is cleaved to (+)-threo-chlorocitric acid, (-)-ery-thro-epoxyaconitic acid is cleaved to (+)-erythro-chloro-10 citric acid and (+)-erythro-epoxyaconitic acid is cleaved to (-)-erythro-chlorocitric acid by an alkali metal chlo-ride dissolved in an aqueous solvent in the presence of an acid, preferably by excess sodium chloride dissolved in water in the presence of one molar equivalent of hydro-5 chloric acid at a temperature within the range of about 50 to 80C, most preferably at about 70C.
(+)-Erythro-chlorocitric acid can be prepared in a high yield process involving the cleavage of the epoxide 20 ring of (+)-erythro-epoxyaconitic acid which can be generated in situ by the epoxidation of cis-aconitic acid or of the corresponding anhydride. The epoxidation is readily performed utilizing hydrogen peroxide in conjunction with an epoxidation catalyst, e.g. tungstic acid or a 25 salt thereof, preferably an alkali metal salt, most preferably the sodium salt. While the epoxidation is preferably carried out in water, containing about 0 molar equivalents to about 2.9 molar equivalents of an alkali metal hydroxide, preferably about 2.5 molar equivalents 30 of sodium hydroxide, an organic solvent such as lower alkanol or a water soluble ether, such as dimethoxyethane, tetrahydrofuran or dioxane, may be employed as a diluent.
The epoxidation is conveniently performed at a temperature of about 0 to 100C, preferably of about 20 to 50C. Without 35 isolation, the resulting (+)-erythro-epoxyaconitic acid or the salt thereof of the formula II can be acidified and then cleaved by treatment with an alkali metal chloride, , .
t~
preferably sodium chloride. Suitable acids include mineral acids, e.g. hydrochloric, sulfuric or phosphoric acid, sulfonic acids, such as methanesulfonic, phenysulfonic or p-toluenesulfonic acid, and strong organic acids, such as trifluoroacetic or trichloroacetic acid. Hydrochloric acid is preferred.
To avoid possible side reactions involving the so-formed (+)-erythro-chlorocitric acid, it is desirable 10 to perform the cleavage in the presence of about one to 10 molar equivalents of the abovementioned acids. Thus, when the epoxidation is carried out in the absence of an alkali metal hydroxide, it i5 desirable to employ about one to about 10 molar equivalents of acid, and when the 15 epoxidation is accomplished in the presence of about 2.5 molar equivalents of alkali metal hydroxide, it is desi-rable to utilize about 3.5 to 12.5 molar equivalents of acid.
- 20 While not narrowly critical, the cleavage reaction temperature is normally maintained within the range of about 50 to 80C, preferably at about 70C.
.. . .
While the afore described process for the preparation 25 of (+)-erythro-chlorocitric acid Ia2 i9 efficiently performed by cleaving the (+)-erythro-epoxyaconitic acid generated in situ, this acid, prepared and isolated by the method disclosed in the U.S. Patent 3,969,772, may also be cleaved to the erythro-chloroacid as hereinbefore 30 described for the cleavage of (+)-threo-epoxyaconitic acid.
While the optically active citric acid derivatives of formulae Ia and Ib are more readily prepared by chlo-~84 rinolysis of the oxirane ring of optically active epoxy-aconitic acid, as hereinbefore described, these compounds may also be prepared from racemic threo- and erythro-ci-tric acid derivatives by resolution methods known in the art.
For example, by employing (+)-p-nitro-a-methylbenzyl-amine and (-)-p-nitro-x-methylbenzylamine sequentially as the resolving agents, (+)-erythro-chlorocitric acid 10 may be resolved into its optical antipodes, (+)-erythro-chlorocitric acid and (-)-erythro-chlorocitric acid, by separation of the diastereoisomeric salts so formed, according to the procedure outlined in U.S.
Patent 3,901,915.
Further, (+)-threo-chlorocitric acid-R-lactone of formulaIbcan beresolved into its optically active anti-podes by conventional resolving techniques such as set forth in the preceding paragraph. More particularly, (+)-20 threo-chlorocitric acid-~-lactone can be treated with ~; (+)-p-nitro-~-methylbenzylamine in a lower alkanol, such as methanol, to ~orm the diastereomeric salts of threo-chlorocitric acid-R-lactone. The salts then are separated by known techniques, such as crystallization.
In an additional and highly efficient synthesis of (+)-threo-chlorocitric acid (Ia1), trans-aconitic acid is converted to a readily isolable and highly crystalline mono-alkali metal salt of (+)-threo-epoxyaconitic acid 30 which is cleaved by the hereinbefore described methods, e.g. with sodium chloride in the presence of hydrochloric acid.
The conversion of trans-aconitic acid to a mono-al-35 kali metal salt of (+)-threo-epoxyaconitic acid may be accomplished by one of several processes.
., ~
113~
In the first, trans-aconitic acid is transformed into a di-alkali metal salt of (+)-threo-chlorocitric acid-~-lactone as herein described. Instead of hydrolyzing the R-lactone directly to the chloroacid Ia1 under aci-dic conditions as herein disclosed, it has been foundefficacious to first hydrolyze t`ne ~-lactone function and concomitantly displace the chloro function to a tri-alkali metal of (+)-threo-epoxyaconitic acid under alkaline conditions, then partially neutralize the tri-10 salt to the desired mono-salt.
The alkali induced hydrolysis - displacement of the dialkali metal salt of (+)-threo-chlorocitric acid-~-lactone is performed with an alkali metal hydroxide, 15 preferably potassium hydroxide, while maintaining the reaction temperature between about 0 to 40C, more pre-ferably at about 0 to 25C.
The partial neutralization of the tri-salt of (+)-20 threo-epoxyaconitic acid is accomplished by adjusting the pH of the hydrolysis - displacement reaction mixture to a value within the range of about 7.0 to 7.5, preferably to a value of about 7.2, cooling the resulting reaction mixture to a temperature of about -20 to 20C, preferably - 25 to about 0 to 5C, adding about two molar-equivalents of acid, collecting the precipitate and purifying it by recrystallization from water or water-alkanol mixtures, water being preferred.
In the second process, trans-aconitic acid is chloro-hydrinated to a tri-alkali metal salt of (+)-threo-chlorocitric acid which is cyclized under alkaline condi-tions and partially neutralized under acidic conditions to the tri-alkali metal salt of (+)-threo-epoxyaconitic 35 acid.
The chlorohydrination is carried out by treating trans-~3~47'(~
aconitic acid with an alkali metal hypochlorite, prefer-ably potassium hypochlorite, preformed by the dissolution of chlorine in an alkali metal hydroxide solution, prefera-bly aqueous potassium hydroxide. While the chlorohydrina-tion temperature is not narrowly critical, ik is preferredto perform the reaction at a temperature within the range of about -20 to 25C, more preferably of about -5 to 5C, most preferably of about 0C. About two molar-equivalents of alkali metal hydroxide are initially employed to form 10 a di-alkali metal salt of trans-aconitic acid and two additional molar-equivalents of alkali metal hydroxide are subsequently employed to form sufficient alkali metal hypochlorite for the hypochlorination of the di-salt.
The cyclization of the tri-alkali metal salt of (+)-threo-chlorocitric acid to the tri-alkali metal salt of (+)-threo-epoxyaconitic acid is accomplished by treating the chlorohydrination reaction mixture or the tri-alkali metal salt of (+)-threo-chlorocitric acid, dissolved 20 in a suitable solvent, with an alkali metal hydroxide, preferably potassium hydroxide. The cyclization temperature is not narrowly critical. Nevertheless it is preferred to carry out the reaction at a temperature of about 15 to 60C, more preferably at about 25C. Suitable cyclization 25 solvents include water and mixtures of water and lower alkanols. Water is preferred.
The partial neutralization of the tri-alkali metal salt of (+)-threo-epoxyaconitic acid is effected by treating 30 it, or the reaction mixture in which it is derived, with a mineral or organic acid according to the hereinbefore described procedure for the related conversion of the di-alkali metal salt of (+)-threo-chlorocitric acid-~-lactone.
In the third process, a variant of the second method, about two-thirds of a molar-equivalent of trans-aconitic :1~, 3~t~
acid is treated with about two molar-equivalents of an alkali metal hydroxide, preferably potassium hydroxide, in an appropriate solvent, followed by about one molar-equivalents of preformed alkali metal hypochlorite, pre-ferably potassium hypochlorite, and about one-third mo-lar-equivalents of trans-aconitic acid to form a tri-al-kali metal salt of (+)-threo-chlorocitric acid.
As appropriate solvent there may be mentioned water 10 and mixtures of water and lower alkanols. Water is pre-ferred. While the hypochlorination temperature is not narrowly critical, it is preferable to perform the reac-tion at a temperature from about -20 to 10C, more pre-ferably from about -10 to -5C.
The so obtained tri-salt is transformed to the mono-alkali metal salt of (+)-threo-epoxyaconitic acid by the methods hereinbefore described in the description of the first process.
In the fourth process, (+)-threo-epoxyaconitic acid is converted to its mono-alkali metal salt, preferably the mono-potassium salt, by treatment of the acid with about one equivalent of an alkali metal hydroxide, 25 preferably potassium hydroxide, in a suitable solvent, such as water and mixtures of water and lower alkanols.
It is preferred to carry out the reaction at about 5C, although the temperature is not critical. The mono-salt so obtained, is isolated and purified as hereinbefore 30 disclosed for the product of the other variants.
The mono-alkali metal salts of (+)-threo-epoxyaconitic acid are generally isolated as the monohydrates.
(-)-Threo-chlorocitric acid may also be prepared by neutralizing a mono-alkali metal salt of (+)-threo-epoxyaconitic acid to (+)-threo-epoxyaconitic acid, which ~!.3~
'';
is then resolved into (+)-threo-epoxyaconitic acid via its bis (+)-p-nitro-a-methylbenzylamine salt and clea-ved int~ (-)-threo-chlorocitric acid as described herein-before.
The neutralization is conveniently performed by trea-ting the mono-alkali metal salt, preferably the potassium salt, with a strong acid in an appropriate solvent. Among strong acids there may be mentioned mineral acids, such 10 as hydrochloric, hydrobromic, nitric, perchloric and sul-furic acid, and organic acids, such as methanesulfonic, benzenesulfonic, p-toluenesulfonic, trifluoroacetic and trichloroacetic acid. Among appropriate solvents there may be mentioned water, lower alkanols, mixtures of water 15 and lower alkanols and ketones, such as acetone, methyl-ethyl ketone and diethylketone. Mineral acids and keto-nes, particularly sulfuric acid and acetone, are preferred.
~` Of particular interest as anorectic agents are the 20 compounds of formula Ia and the pharmaceutically accep-table salts thereof, more particularly (-)-threo-chloro-citric acid and pharmaceutically acceptable salts thereof, which are significantly more active in reducing food con-- sumption than hydroxycitric acid or citric acid, as can 25 be seen from the following test reports.
~. .
Female rats weighing 150 to 175 g,were housed in indi-vidual cages, fasted 48 hr, then fed a 70 o/o glucose diet from 8 to 11 a.m. Following 5 to 13 days alimenta-30 tion, rats were dosed with the appropriate compounds orallyby intubation 1~2 hr before the 3 hr meal. Food cups were weighed immediately after the meal. The control group consists of 31 rats while each drug treated group corsists of 5 to 12 rats. The results are given in Table I.
g, - ~.3~'70 ~ ~o' o o~ ~ o ~
L O O 1~ ~ ~ _ O
r o O
~l ~ ~
E ~ 0 o ~o r~ ~>
O _ o O
O ~0 ,q~ +, +, +1 +, +1 .
E .. - 0~ cr~ o Lo c C ~0 . ~
O ~I' O et oo L~
H~0 u O o ~) c~ ) R ~ o c : s E
O ~ ~ * * * * ~ .
~ In ~ o ~
, R O O o O o O O ~U
+l t~l +l +l +l +l +l +l +l ~
~ ca et ~ ~
_~ _ ~
o ._ ~ s ~ ~ . ~ :~
+ ~ ~ 3 ~_) ~1 ~0 ~ _ o o o' o ~ ~O
1~3134~
Female rats weighing 130 to 150 g, were housed in individual cages, fasted 48 hr, then ~ed a 70 o/o glu-cose diet from 8 to 11 a.m. Following 5 to 12 days ali-mentation, rats were dosed with the appropriate compounds orally by intubation 1/2 hr before the 3 hr meal. Food cups were weighed immediately after the meal. The con-trol group consisted of 5 to 10 rats, while the experi-mental group consisted of 4 to 6 rats. The results are given in Table II.
.: .
~ .
.. .
113134~7V
-- 1 5 _ +, ~ o I ~ a~ u~ a~
,~o~ o O r v) C`l O 1~ a- CD
E O c~ ~0 00 O.
O
O O _ _ O _ O
. ~ ~ +~ +1 +1 ~1 +1 +1 ~ Ir) I~ _ C~l N ~n C~.l ~ O
~ ~ LLI
+E ~ U ~
~0 ~ s 1~l384~7~) The citric acid derivatives of the present invention can be made up in the form of conventional pharmaceuti-cal preparations containing, in addition to the active ingredients, carrier material, such as conventional orga-nic or inorganic inert pharmaceutical adjuvants, addi-tives and excipients suitable for parenteral or enteral administration, e.g. water, gelatin, lactose, starch, magnesium stearate, talc, vegetable oil or gums. They can be administered in conventional pharmaceutical forms, 10 e.g. solid forms, for example tablets, dragees, capsules or suppositories; or in liquid forms, for example sus-pensions or emulsions. Moreover, the pharmaceutical com-po~sitions can be subjected to conventional pharmaceuti-cal expedients, such as sterilization, and can contain 15 conventional pharmaceutical excipients such as preserva-tives, stabilizing or emulsifying agents, salts for the adjustment of osmotic pressure or buffers. The composi-tion can also contain other therapeutically active mate-rials.
` 20 A suitable pharmaceutical dosage unit can contain from about 10 to 1000 mg of (-)-threo-chlorocitric acid or its isomers. Suitable parenteral and oral dosage regi-mens in mammals comprise from about 1 to 150 mg/kg per day.
The citric acid derivatives of the present invention can also be compounded with a feed additive, premix or concentrate for administration to an animal. -A feed premix or complete feed can e.g. contain suffi-cient active ingredient to provide from about 0.0025 to 1.00 o/o, preferably, about 0.0625 to 0.40 o/o, most pre-ferably about 0.125 o/o, by weight of the daily feed con-sumption.
3?3'~70 Example l Preparation of the starting material.
174 g of trans-aconitic acid was added portionwise to a stirred solution of 120 g of sodium hydroxide in 400 ml of water. The temperature was maintained at 25.
When the acid had completely dissolved, the solution was at pH 7.5.
The process.
The solution was cooled to 5 and purged with argon.
Chlorine gas was then added to the stirred mixture as fast as it could be consumed. The temperature was main-tained at 10-15. When no more gas was absorbed, the 15 addition o~ chlorine was stopped and the mixture was stirred at iO for 10 minutes. Excess chlorine gas was purged by bubbing argon gas through the mixture.
.
The reaction was acidified using 175 ml conc. hydro-20 chloric acid and then heate`d at 70 for 1 hour to hydrolyze the ~-lactone. The solution was concentrated to dryness and the residue was triturated with ethyl acetate. The combined extracts were filtered to remove residual sodium chloride and then dried. Evaporation of the solvent gave 25 a solid which was redissolved in ethyl acetate. The solution was diluted with carbon tetrachloride. After stirring, the solid which had ~ormed was recovered by filtration to give 102.0 g of (+)-threo-chlorocitric acid, mp 96-101.
The mother liquors were concentrated to dryness and then crystallized as above to give an addition 60.7 g of pure (+)-threo-chlorocitric acid.
Example 2 To a solution of 123 g o~ mono-potassium (+)-- threo-epoxyaconitic acid monohydrate and 28 g o~ potassium ..
chloride in 120 ml of water, was added 88 ml of conc.
hydrochloric acid. The reaction mixture was heated at 70 for 15 nours, allowed to cool to room temperature and concentrated. Ethyl acetate (250 ml) was added and the mixture was agitated at 40. The precipitated potas-sium chloride was collected and washed with 350 ml of ethyl acetate. The filtrate was evaporated to dryness.
The residue was dissolved in ethyl acetate, treated with anhydrous magnesium sulfate and filtered. The filter cake was washed with ethyl acetate. Carbon tetrachloride was added to the filtrate. The mixture was seeded with crys-talline (+)-threo-chlorocitric acid monohydrate, stir-red for 2 hours and allowed to stand for 16 hours in a refrigerator. The precipitate was collected, washed with carbon tetrachloride-ethyl acetate (3:1) and dried to afford 70.9 g of (+)-threo-chlorocitric acid monohydrate, m.p. 74-76.
The mother liquors were evaporated to dryness. The residue was dissolved in 125 ml of ethyl acetate and trea-ted with carbon tetrachloride to give 20.7 g of product.
; A 91.0 g-portion of the combined first and second crops was dissolved in 250 ml of ethyl acetate and trea-ted with 500 ml of carbon tetrachloride. The solution was seeded with crystalline (+)-threo-chlorocitric acid monohydrate and stored in a refrigerator overnight. The precipitate was collected, washed with carbon tetrachloride and ethyl acetate and dried to yield 84.3 g of purified 30 product, m.p. 74_76 .
Example 3 74.0 g of cis-aconitic anhydride was dissolved in 200 ml of water containing 100 g ice. A solution of 46.25 g of sodium hydroxide in 100 ml of water was added slowly with stirring. The temperature was held below 20. Then 1~3~}4~
~ g 15.25 g sodium tungstate dihydrate, followed by 55.5 ml of 30 o/o hydrogen peroxide was added to the mixture.
The stirred solution was warmed to 23. The external heat source was then removed whereupon the heat of reaction caused the mixture temperature to slowly climb to 51.5 over 25 minutes after which it started to decline. After stirring 30-40 minutes, the mixture was treated with 150 ml conc. hydrochloric acid and 150 g sodium chloride and heated at 75 for 15 minutes. In this way the intermediate (+)-erythro-epoxyaconitic acid was converted to (+)-ery-thro-chlorocitric acid. After the reaction mixture was cooled to room temperature, 2.3 g sodium bisulfite was added to destroy residual hydrogen peroxide. The solution was then continuously extracted using ether.
The first extract collected after 21 hours was dried and concentrated to give 73.0 g of crude chlorocitric acid. Crystallization of this material twice from ethyl acetate-carbon tetrachloride furnished essentially pure (+)-erythro-chlorocitric acid, mp 162-164.
A second extract gave an additional 18.5 g of the acid, mp 163-165.
Example 4 A solution of trisodium trans-aconitate prepared from 58.0 g trans-aconitic acid and 40 g sodium hydroxide in 300 ml of water was cooled to 5 and chlorinated as in 30 Example 1. The resulting solution of disodium chlorocitric acid-R-lactone was purged free of excess chlorine gas and then treated with 60 ml 12N hydrochloric acid. The mixture was extracted with ethyl acetate and the extracts were combined and dried. The ethyl acetate solution was 35 concentrated and then diluted with carbon tetrachloride.
The resulting crystalline material was collected by filtration to give 41.5 g of pure (+)-threo-1~3~7(~
The present invention relates to novel citric acid derivatives of the formula H ~ ~ CO2H
~CI la ~ OH
H02C/ ~cH2co2H
and corresponding threo-~-lactones of the formula HO2C ` H
< Cl lb ~
as well as pharmaceutically acceptable salts of these compounds.
The chlorocitric acids of formula Ia and certain star-ting materials and intermediates in the preparation there-of, bear two asymmetric centers and thus exist in two relative stereochemical forms: a threo form and an erythro 25 form. The chlorocitric acid-~-lactones of formula Ib have the threo form. Each form, i.e. the threo form and erythro form, can exist as a racemate and two optical antipodes, the (+)-optical antipode and the (-)-optical antipode.
In conjunction therewith, the threo-erythro nomenclature 30 as defined in J. Amer. Chem. Soc., 74, 5828 (1952) and Experientia, 12, 81 (1956) has been adopted.
Mé/5.11.1979 ~"3!~47~
As used throughout the specification and appended claims, the term "alkali metal" and "alkaline earth me-tal" refer to lithium, sodium and potassium, and calcium, respectively. The term "alkanol" refers to the compound 5 derived by replacement of a proton of a straight or branched chain alkane having 1 to 20 carbon atoms by a hydroxyl moiety. Examples of alkanols include methanol, ethanol and 2-propanol.
The compounds of ~ormulae Ia and Ib and the salts thereof exhibit anorectic activity and are thus useful as anorectic agents for the treatment of obesity in mam-mals. The invention relates to the compounds of formulae Ia and Ib and the pharmaceutically acceptable salts there-15 Of as pharmaceutical, particularly anorectic, agents,as well as to pharmaceutical compositions, particularly anorectic compositions, comprising a compound of formula Ia or Ib or a pharmaceutically acceptable salt thereof, and to a process for the manufacture of such compositions.
The invention also relates to a process for the manu-facture of the compounds of formulae Ia and Ib and of the pharmaceutically acceptable salts thereof, which pro-cess comprises a) for the preparation of a (+)-threo-lactone of formula Ib contacting an aqueous solution of a tri-alkali metal salt or tri-alkaline earth metal salt of cis- or trans-aconitic acid with chlorine or hypochlorous acid 30 and contacting the obtained salt of (~)-threo-chlorocitric acid-R-lactone of the formula ~ -" ' ' . ' ' . , ' ' 1~.3B470 \<CI I b 1 M02C <~co wherein M is an alkali or alkaline earth metal, with an acid, b) for the preparation of (+)-threo-chlorocitric acid of the formula ~ OCH lla 1 20 hydrolyzing a compound of formula Ib or Ib1, c) for the preparation of a compound of formula Ia clea-ving epoxyaconitic acid with an alkali metal chloride or alkaline earth metal chloride in an aqueous solvent 25 in the presence of an acid, d) for the preparation of (+)-erythro-chlorocitric acid of the formula ~ ~Cl la2 ~OH
H 02C/ \CH2C 2 H
35 cleaving an epoxide of the formula 1~3~4';'~
M~02C H
wherein M' is an alkali metal and R is hydrogen or M', 10 with in alkali metal chloride in an aqueous solvent in the presence of an acid, e) if desired, resolving an obtained (+)-threorcitric acid derivative of formula Ia or Ib or (+)-erythro-citric acid derivative 15 of formula Ia into its optically active antipodes and isolating a desired antipode, f) if desiredlisolating an obtained compound of formula Ia or Ib in form of a pharmaceutically àcceptable salt 20 thereof.
The aqueous solution of process step a), which can be obtained by dissolving aconitic acid in an aqueous solution of an alkali or alkaline earth metal hydroxide, 25 preferably sodium or potassium hydroxide, is conveniently cooled to about 0 to 30C, preferably 5C, and treated with excess chlorine or hypochlorous acid, preferably chlorine.
Suitable aqueous solvents include water and mixtures of water and a lower alkanol, water and an ether, such as dimethoxyethane, tetrahydrofuran or dioxane, and water - and a polar aprotic solvent, such as dimethylacetamide, dimethylformamide, dimethylsul~oxide or hexamethylphos-35 phoramide.
Among acids suitable for the conversion of the salt ,. ..
~8~
Ib1 to the corresponding free acid Ib may be mentioned mineral acids, e.g. hydrochloric, sulfuric, nitric or phosphoric acid, sulfonic acids, such as methanesulfonic, phenylsulfonic or p-toluenesulfonic acid, and strong orga-nic carboxylic ~cids, such as trifluoro- or trichloroace-tic acid.
The hydrolysis of the ~-lactone function of the di-acid of formula Ib or the disalt thereof of formula Ib1 10 according to process step b), can be accomplished by sus-pending or dissolving the diacid or the disalt in an aqueous solvent containing an acid, such as those employed for the acidification of the disalt Ib1 to the diacid Ib, ard heating the resulting reaction system, conveniently 15 at a-temperature of about 30 to 80C to complete the hydrolysis. A temperature of about 50 to 70C, particu-larly of about 70C, is preferred.
While the chlorohydrination of step a) and the hy-20 drolysis of step b) may be performed stepwise, it is moreconvenient and efficient to acidify the disalt Ib1 and heat the resulting reaction mixture to complete the hy-drolysis of the diacid Ib to afford (+)-threo-chlorocitric acid. Thus, upon completion of the chlorohydrination, 25 the reaction mixture is acidified, preferably with a mineral acid, most preferably hydrochloric acid, and heated from about 30 to 100C, preferably from about 50 to 90C, most preferably at about 70C, to complete the conversion of the B-lactone Ib to the acid Ia1.
The cleavage of step c) is carried out with an al-kali or alkaline earth metal chloride in an aqueous sol-vent in the presence of an acid.
Thus (+)-threo-epoxyaconitic acid may be cleaved by an alkali metal chloride dissolved in an aqueous solvent in the presence of an acid, preferably by excess sodium ~3~
chloride dissolved in water in the presence of one molar equivalent of hydrochloric acid at a temperature within the range of about 50 to 80C, most preferably at about Likewise, (+)-threo-epoxyaconitic acid is cleaved to (-)-threo-chlorocitric acid, (-)-threo-epoxyaconitic acid is cleaved to (+)-threo-chlorocitric acid, (-)-ery-thro-epoxyaconitic acid is cleaved to (+)-erythro-chloro-10 citric acid and (+)-erythro-epoxyaconitic acid is cleaved to (-)-erythro-chlorocitric acid by an alkali metal chlo-ride dissolved in an aqueous solvent in the presence of an acid, preferably by excess sodium chloride dissolved in water in the presence of one molar equivalent of hydro-5 chloric acid at a temperature within the range of about 50 to 80C, most preferably at about 70C.
(+)-Erythro-chlorocitric acid can be prepared in a high yield process involving the cleavage of the epoxide 20 ring of (+)-erythro-epoxyaconitic acid which can be generated in situ by the epoxidation of cis-aconitic acid or of the corresponding anhydride. The epoxidation is readily performed utilizing hydrogen peroxide in conjunction with an epoxidation catalyst, e.g. tungstic acid or a 25 salt thereof, preferably an alkali metal salt, most preferably the sodium salt. While the epoxidation is preferably carried out in water, containing about 0 molar equivalents to about 2.9 molar equivalents of an alkali metal hydroxide, preferably about 2.5 molar equivalents 30 of sodium hydroxide, an organic solvent such as lower alkanol or a water soluble ether, such as dimethoxyethane, tetrahydrofuran or dioxane, may be employed as a diluent.
The epoxidation is conveniently performed at a temperature of about 0 to 100C, preferably of about 20 to 50C. Without 35 isolation, the resulting (+)-erythro-epoxyaconitic acid or the salt thereof of the formula II can be acidified and then cleaved by treatment with an alkali metal chloride, , .
t~
preferably sodium chloride. Suitable acids include mineral acids, e.g. hydrochloric, sulfuric or phosphoric acid, sulfonic acids, such as methanesulfonic, phenysulfonic or p-toluenesulfonic acid, and strong organic acids, such as trifluoroacetic or trichloroacetic acid. Hydrochloric acid is preferred.
To avoid possible side reactions involving the so-formed (+)-erythro-chlorocitric acid, it is desirable 10 to perform the cleavage in the presence of about one to 10 molar equivalents of the abovementioned acids. Thus, when the epoxidation is carried out in the absence of an alkali metal hydroxide, it i5 desirable to employ about one to about 10 molar equivalents of acid, and when the 15 epoxidation is accomplished in the presence of about 2.5 molar equivalents of alkali metal hydroxide, it is desi-rable to utilize about 3.5 to 12.5 molar equivalents of acid.
- 20 While not narrowly critical, the cleavage reaction temperature is normally maintained within the range of about 50 to 80C, preferably at about 70C.
.. . .
While the afore described process for the preparation 25 of (+)-erythro-chlorocitric acid Ia2 i9 efficiently performed by cleaving the (+)-erythro-epoxyaconitic acid generated in situ, this acid, prepared and isolated by the method disclosed in the U.S. Patent 3,969,772, may also be cleaved to the erythro-chloroacid as hereinbefore 30 described for the cleavage of (+)-threo-epoxyaconitic acid.
While the optically active citric acid derivatives of formulae Ia and Ib are more readily prepared by chlo-~84 rinolysis of the oxirane ring of optically active epoxy-aconitic acid, as hereinbefore described, these compounds may also be prepared from racemic threo- and erythro-ci-tric acid derivatives by resolution methods known in the art.
For example, by employing (+)-p-nitro-a-methylbenzyl-amine and (-)-p-nitro-x-methylbenzylamine sequentially as the resolving agents, (+)-erythro-chlorocitric acid 10 may be resolved into its optical antipodes, (+)-erythro-chlorocitric acid and (-)-erythro-chlorocitric acid, by separation of the diastereoisomeric salts so formed, according to the procedure outlined in U.S.
Patent 3,901,915.
Further, (+)-threo-chlorocitric acid-R-lactone of formulaIbcan beresolved into its optically active anti-podes by conventional resolving techniques such as set forth in the preceding paragraph. More particularly, (+)-20 threo-chlorocitric acid-~-lactone can be treated with ~; (+)-p-nitro-~-methylbenzylamine in a lower alkanol, such as methanol, to ~orm the diastereomeric salts of threo-chlorocitric acid-R-lactone. The salts then are separated by known techniques, such as crystallization.
In an additional and highly efficient synthesis of (+)-threo-chlorocitric acid (Ia1), trans-aconitic acid is converted to a readily isolable and highly crystalline mono-alkali metal salt of (+)-threo-epoxyaconitic acid 30 which is cleaved by the hereinbefore described methods, e.g. with sodium chloride in the presence of hydrochloric acid.
The conversion of trans-aconitic acid to a mono-al-35 kali metal salt of (+)-threo-epoxyaconitic acid may be accomplished by one of several processes.
., ~
113~
In the first, trans-aconitic acid is transformed into a di-alkali metal salt of (+)-threo-chlorocitric acid-~-lactone as herein described. Instead of hydrolyzing the R-lactone directly to the chloroacid Ia1 under aci-dic conditions as herein disclosed, it has been foundefficacious to first hydrolyze t`ne ~-lactone function and concomitantly displace the chloro function to a tri-alkali metal of (+)-threo-epoxyaconitic acid under alkaline conditions, then partially neutralize the tri-10 salt to the desired mono-salt.
The alkali induced hydrolysis - displacement of the dialkali metal salt of (+)-threo-chlorocitric acid-~-lactone is performed with an alkali metal hydroxide, 15 preferably potassium hydroxide, while maintaining the reaction temperature between about 0 to 40C, more pre-ferably at about 0 to 25C.
The partial neutralization of the tri-salt of (+)-20 threo-epoxyaconitic acid is accomplished by adjusting the pH of the hydrolysis - displacement reaction mixture to a value within the range of about 7.0 to 7.5, preferably to a value of about 7.2, cooling the resulting reaction mixture to a temperature of about -20 to 20C, preferably - 25 to about 0 to 5C, adding about two molar-equivalents of acid, collecting the precipitate and purifying it by recrystallization from water or water-alkanol mixtures, water being preferred.
In the second process, trans-aconitic acid is chloro-hydrinated to a tri-alkali metal salt of (+)-threo-chlorocitric acid which is cyclized under alkaline condi-tions and partially neutralized under acidic conditions to the tri-alkali metal salt of (+)-threo-epoxyaconitic 35 acid.
The chlorohydrination is carried out by treating trans-~3~47'(~
aconitic acid with an alkali metal hypochlorite, prefer-ably potassium hypochlorite, preformed by the dissolution of chlorine in an alkali metal hydroxide solution, prefera-bly aqueous potassium hydroxide. While the chlorohydrina-tion temperature is not narrowly critical, ik is preferredto perform the reaction at a temperature within the range of about -20 to 25C, more preferably of about -5 to 5C, most preferably of about 0C. About two molar-equivalents of alkali metal hydroxide are initially employed to form 10 a di-alkali metal salt of trans-aconitic acid and two additional molar-equivalents of alkali metal hydroxide are subsequently employed to form sufficient alkali metal hypochlorite for the hypochlorination of the di-salt.
The cyclization of the tri-alkali metal salt of (+)-threo-chlorocitric acid to the tri-alkali metal salt of (+)-threo-epoxyaconitic acid is accomplished by treating the chlorohydrination reaction mixture or the tri-alkali metal salt of (+)-threo-chlorocitric acid, dissolved 20 in a suitable solvent, with an alkali metal hydroxide, preferably potassium hydroxide. The cyclization temperature is not narrowly critical. Nevertheless it is preferred to carry out the reaction at a temperature of about 15 to 60C, more preferably at about 25C. Suitable cyclization 25 solvents include water and mixtures of water and lower alkanols. Water is preferred.
The partial neutralization of the tri-alkali metal salt of (+)-threo-epoxyaconitic acid is effected by treating 30 it, or the reaction mixture in which it is derived, with a mineral or organic acid according to the hereinbefore described procedure for the related conversion of the di-alkali metal salt of (+)-threo-chlorocitric acid-~-lactone.
In the third process, a variant of the second method, about two-thirds of a molar-equivalent of trans-aconitic :1~, 3~t~
acid is treated with about two molar-equivalents of an alkali metal hydroxide, preferably potassium hydroxide, in an appropriate solvent, followed by about one molar-equivalents of preformed alkali metal hypochlorite, pre-ferably potassium hypochlorite, and about one-third mo-lar-equivalents of trans-aconitic acid to form a tri-al-kali metal salt of (+)-threo-chlorocitric acid.
As appropriate solvent there may be mentioned water 10 and mixtures of water and lower alkanols. Water is pre-ferred. While the hypochlorination temperature is not narrowly critical, it is preferable to perform the reac-tion at a temperature from about -20 to 10C, more pre-ferably from about -10 to -5C.
The so obtained tri-salt is transformed to the mono-alkali metal salt of (+)-threo-epoxyaconitic acid by the methods hereinbefore described in the description of the first process.
In the fourth process, (+)-threo-epoxyaconitic acid is converted to its mono-alkali metal salt, preferably the mono-potassium salt, by treatment of the acid with about one equivalent of an alkali metal hydroxide, 25 preferably potassium hydroxide, in a suitable solvent, such as water and mixtures of water and lower alkanols.
It is preferred to carry out the reaction at about 5C, although the temperature is not critical. The mono-salt so obtained, is isolated and purified as hereinbefore 30 disclosed for the product of the other variants.
The mono-alkali metal salts of (+)-threo-epoxyaconitic acid are generally isolated as the monohydrates.
(-)-Threo-chlorocitric acid may also be prepared by neutralizing a mono-alkali metal salt of (+)-threo-epoxyaconitic acid to (+)-threo-epoxyaconitic acid, which ~!.3~
'';
is then resolved into (+)-threo-epoxyaconitic acid via its bis (+)-p-nitro-a-methylbenzylamine salt and clea-ved int~ (-)-threo-chlorocitric acid as described herein-before.
The neutralization is conveniently performed by trea-ting the mono-alkali metal salt, preferably the potassium salt, with a strong acid in an appropriate solvent. Among strong acids there may be mentioned mineral acids, such 10 as hydrochloric, hydrobromic, nitric, perchloric and sul-furic acid, and organic acids, such as methanesulfonic, benzenesulfonic, p-toluenesulfonic, trifluoroacetic and trichloroacetic acid. Among appropriate solvents there may be mentioned water, lower alkanols, mixtures of water 15 and lower alkanols and ketones, such as acetone, methyl-ethyl ketone and diethylketone. Mineral acids and keto-nes, particularly sulfuric acid and acetone, are preferred.
~` Of particular interest as anorectic agents are the 20 compounds of formula Ia and the pharmaceutically accep-table salts thereof, more particularly (-)-threo-chloro-citric acid and pharmaceutically acceptable salts thereof, which are significantly more active in reducing food con-- sumption than hydroxycitric acid or citric acid, as can 25 be seen from the following test reports.
~. .
Female rats weighing 150 to 175 g,were housed in indi-vidual cages, fasted 48 hr, then fed a 70 o/o glucose diet from 8 to 11 a.m. Following 5 to 13 days alimenta-30 tion, rats were dosed with the appropriate compounds orallyby intubation 1~2 hr before the 3 hr meal. Food cups were weighed immediately after the meal. The control group consists of 31 rats while each drug treated group corsists of 5 to 12 rats. The results are given in Table I.
g, - ~.3~'70 ~ ~o' o o~ ~ o ~
L O O 1~ ~ ~ _ O
r o O
~l ~ ~
E ~ 0 o ~o r~ ~>
O _ o O
O ~0 ,q~ +, +, +1 +, +1 .
E .. - 0~ cr~ o Lo c C ~0 . ~
O ~I' O et oo L~
H~0 u O o ~) c~ ) R ~ o c : s E
O ~ ~ * * * * ~ .
~ In ~ o ~
, R O O o O o O O ~U
+l t~l +l +l +l +l +l +l +l ~
~ ca et ~ ~
_~ _ ~
o ._ ~ s ~ ~ . ~ :~
+ ~ ~ 3 ~_) ~1 ~0 ~ _ o o o' o ~ ~O
1~3134~
Female rats weighing 130 to 150 g, were housed in individual cages, fasted 48 hr, then ~ed a 70 o/o glu-cose diet from 8 to 11 a.m. Following 5 to 12 days ali-mentation, rats were dosed with the appropriate compounds orally by intubation 1/2 hr before the 3 hr meal. Food cups were weighed immediately after the meal. The con-trol group consisted of 5 to 10 rats, while the experi-mental group consisted of 4 to 6 rats. The results are given in Table II.
.: .
~ .
.. .
113134~7V
-- 1 5 _ +, ~ o I ~ a~ u~ a~
,~o~ o O r v) C`l O 1~ a- CD
E O c~ ~0 00 O.
O
O O _ _ O _ O
. ~ ~ +~ +1 +1 ~1 +1 +1 ~ Ir) I~ _ C~l N ~n C~.l ~ O
~ ~ LLI
+E ~ U ~
~0 ~ s 1~l384~7~) The citric acid derivatives of the present invention can be made up in the form of conventional pharmaceuti-cal preparations containing, in addition to the active ingredients, carrier material, such as conventional orga-nic or inorganic inert pharmaceutical adjuvants, addi-tives and excipients suitable for parenteral or enteral administration, e.g. water, gelatin, lactose, starch, magnesium stearate, talc, vegetable oil or gums. They can be administered in conventional pharmaceutical forms, 10 e.g. solid forms, for example tablets, dragees, capsules or suppositories; or in liquid forms, for example sus-pensions or emulsions. Moreover, the pharmaceutical com-po~sitions can be subjected to conventional pharmaceuti-cal expedients, such as sterilization, and can contain 15 conventional pharmaceutical excipients such as preserva-tives, stabilizing or emulsifying agents, salts for the adjustment of osmotic pressure or buffers. The composi-tion can also contain other therapeutically active mate-rials.
` 20 A suitable pharmaceutical dosage unit can contain from about 10 to 1000 mg of (-)-threo-chlorocitric acid or its isomers. Suitable parenteral and oral dosage regi-mens in mammals comprise from about 1 to 150 mg/kg per day.
The citric acid derivatives of the present invention can also be compounded with a feed additive, premix or concentrate for administration to an animal. -A feed premix or complete feed can e.g. contain suffi-cient active ingredient to provide from about 0.0025 to 1.00 o/o, preferably, about 0.0625 to 0.40 o/o, most pre-ferably about 0.125 o/o, by weight of the daily feed con-sumption.
3?3'~70 Example l Preparation of the starting material.
174 g of trans-aconitic acid was added portionwise to a stirred solution of 120 g of sodium hydroxide in 400 ml of water. The temperature was maintained at 25.
When the acid had completely dissolved, the solution was at pH 7.5.
The process.
The solution was cooled to 5 and purged with argon.
Chlorine gas was then added to the stirred mixture as fast as it could be consumed. The temperature was main-tained at 10-15. When no more gas was absorbed, the 15 addition o~ chlorine was stopped and the mixture was stirred at iO for 10 minutes. Excess chlorine gas was purged by bubbing argon gas through the mixture.
.
The reaction was acidified using 175 ml conc. hydro-20 chloric acid and then heate`d at 70 for 1 hour to hydrolyze the ~-lactone. The solution was concentrated to dryness and the residue was triturated with ethyl acetate. The combined extracts were filtered to remove residual sodium chloride and then dried. Evaporation of the solvent gave 25 a solid which was redissolved in ethyl acetate. The solution was diluted with carbon tetrachloride. After stirring, the solid which had ~ormed was recovered by filtration to give 102.0 g of (+)-threo-chlorocitric acid, mp 96-101.
The mother liquors were concentrated to dryness and then crystallized as above to give an addition 60.7 g of pure (+)-threo-chlorocitric acid.
Example 2 To a solution of 123 g o~ mono-potassium (+)-- threo-epoxyaconitic acid monohydrate and 28 g o~ potassium ..
chloride in 120 ml of water, was added 88 ml of conc.
hydrochloric acid. The reaction mixture was heated at 70 for 15 nours, allowed to cool to room temperature and concentrated. Ethyl acetate (250 ml) was added and the mixture was agitated at 40. The precipitated potas-sium chloride was collected and washed with 350 ml of ethyl acetate. The filtrate was evaporated to dryness.
The residue was dissolved in ethyl acetate, treated with anhydrous magnesium sulfate and filtered. The filter cake was washed with ethyl acetate. Carbon tetrachloride was added to the filtrate. The mixture was seeded with crys-talline (+)-threo-chlorocitric acid monohydrate, stir-red for 2 hours and allowed to stand for 16 hours in a refrigerator. The precipitate was collected, washed with carbon tetrachloride-ethyl acetate (3:1) and dried to afford 70.9 g of (+)-threo-chlorocitric acid monohydrate, m.p. 74-76.
The mother liquors were evaporated to dryness. The residue was dissolved in 125 ml of ethyl acetate and trea-ted with carbon tetrachloride to give 20.7 g of product.
; A 91.0 g-portion of the combined first and second crops was dissolved in 250 ml of ethyl acetate and trea-ted with 500 ml of carbon tetrachloride. The solution was seeded with crystalline (+)-threo-chlorocitric acid monohydrate and stored in a refrigerator overnight. The precipitate was collected, washed with carbon tetrachloride and ethyl acetate and dried to yield 84.3 g of purified 30 product, m.p. 74_76 .
Example 3 74.0 g of cis-aconitic anhydride was dissolved in 200 ml of water containing 100 g ice. A solution of 46.25 g of sodium hydroxide in 100 ml of water was added slowly with stirring. The temperature was held below 20. Then 1~3~}4~
~ g 15.25 g sodium tungstate dihydrate, followed by 55.5 ml of 30 o/o hydrogen peroxide was added to the mixture.
The stirred solution was warmed to 23. The external heat source was then removed whereupon the heat of reaction caused the mixture temperature to slowly climb to 51.5 over 25 minutes after which it started to decline. After stirring 30-40 minutes, the mixture was treated with 150 ml conc. hydrochloric acid and 150 g sodium chloride and heated at 75 for 15 minutes. In this way the intermediate (+)-erythro-epoxyaconitic acid was converted to (+)-ery-thro-chlorocitric acid. After the reaction mixture was cooled to room temperature, 2.3 g sodium bisulfite was added to destroy residual hydrogen peroxide. The solution was then continuously extracted using ether.
The first extract collected after 21 hours was dried and concentrated to give 73.0 g of crude chlorocitric acid. Crystallization of this material twice from ethyl acetate-carbon tetrachloride furnished essentially pure (+)-erythro-chlorocitric acid, mp 162-164.
A second extract gave an additional 18.5 g of the acid, mp 163-165.
Example 4 A solution of trisodium trans-aconitate prepared from 58.0 g trans-aconitic acid and 40 g sodium hydroxide in 300 ml of water was cooled to 5 and chlorinated as in 30 Example 1. The resulting solution of disodium chlorocitric acid-R-lactone was purged free of excess chlorine gas and then treated with 60 ml 12N hydrochloric acid. The mixture was extracted with ethyl acetate and the extracts were combined and dried. The ethyl acetate solution was 35 concentrated and then diluted with carbon tetrachloride.
The resulting crystalline material was collected by filtration to give 41.5 g of pure (+)-threo-1~3~7(~
- 2~) -chlorocitric acid-~-lactone, mp 162-164.
Example ~
30 g of (+)-erythro-chlorocitric acid was dissolved in 175 ml of a methanol-water mixture (49:1). The solution was cooled to 15 and 39.5 g (-)-p-nitro-a-methylbenzyl-amine in 75 ml of the same methanol-water mixture was added. The mixture was stirred at room temperatur for 18 hours. The solids were collected by filtration and then washed with ethanol and ether to give 24.0 g of partially resolved (+)-erythro-chlorocitric acid-bis(-)-p-nitro-a-methylbenzylamine salt.
The impure salt was then split in the following manner:
hydrogen chloride gas was bubbled through a stirred sus-pension of finely divided salt (27.1 g) in ether for 30 minutes. The resulting solid (-)-p-nitro-a-methylbenzyl-amine hydrochloride (19.9 g, mp 247-249) was removed 20 by filtration and the filtrate was concentrated to give 10.9 g of partially resolved (+)-erythro-chlorocitric acid a~ an oil (65 o/o optical purity).
The (-)-p-nitro-a-methylbenzylamine hydrochloride 25 was partitioned between dichloromethane and 1N sodium hydroxide. The amine recovered from this process (1~.6 g) in 40 ml methanol-water (49:1) was added to a solution of the crude (+)-erythro-chlorocitric acid in 40 ml metha-nol-water (49:1) and the mixture, after stirring, deposi-30 ted 18.1 g of enriched bis-amine chlorocitrate.
The salt was again split using ethereal hydrogen chlo-ride and was then reformed in the manner described above.
This gave 14.4 g of the bis-amine chlorocitrate. The (+)-35 erythro-chlorocitric acid recovered from the latest salt was recrystallized from ethyl acetate-carbon tetrachloride to give 4.3 g of material (29 o/o chemical yield) which 1~38~7() was 85 o/o optically pure.
The mother liquors of the solution of the partially resolved (+)-erythro-chlorocitric acid-bis(-)-p-nitro-a-methylbenzylamine salt were treated with 13 ml of conc.hydrochloric acid and evaported. 1,2-Dimethoxyethane was added and the ~olution was evaporated to dryness. Ether was added to the residue, the mixture was stirred and the precipitate was collected to afford 29.2 g of (-)-p-10 nitro-a-methylbenzylamine hydrochloride.
The filtrate was concentrated to dryness and the resi-due, rich in (-)-erythro-chlorocitric acid, was dissolved in 90 ml of methanol-water (49:1). A solution of 25.3 g 15 of (+)-p-nitro-a-methylbenzylamine and 50 ml of methanol-water (49:1) was added. The resulting mixture was stirred for 20 hours and the precipitate was collected to afford 15.0 g of bis-(+)-p-nitro-a-methylbenzylamine salt en-riched in (-)-erythro-chlorocitric acid. The salt was 20 suspended in 185 ml of ether and hydrogen chloride was added to the suspension. The precipitated (+)-p-nitro-a-methylbenzylamine hydrochloride (10.7 g) was collected on a filter. The filtrate was concentrated to dryness and the residue was dissolved in 40 ml of methanol-water (49:1). To the methanol-water solution was added a solu-tion of 8.9 g of (+)-p-nitro-a-methylbenzylamine and 15 ml of methanol-water (49:1) and the solution was stirred for 2.5 hours. The precipitate (11.75 g) enriched in (-)-erythro-chlorocitric acid-bis-(+)-p-nitro-a-methylbenzyl-30 amine salt, was suspended in ether and the resulting sus-pension was saturated with hydrogen chloride. The preci-pitated (+)-p-nitro-a-methylbenzylamine hydrochloride (8.o9 g) was collected and the filtrate was concentrated.
Recrystallization of the residue from ethyl acetate-car-35 bon tetrachloride gave 3.9 g of (-)-erythro-chlorocitric acid (85 o/o optical purity).
.
' ~
'.
~3~4~0 Example 6 10S g (+)-threo-epoxyaconitic acid monohydrate was dissolved in 150 ml of water containing 43 ml conc. hy-drochloric acid. Sodium chloride (50 g) was added to the ~; stirred solution and the mixture was heated at 70 for 12 hours. The solution wa3 evaporated to dryness and the residue was triturated with 400 ml ethyl acetate. The mixture was filtered and the filtrate was decolorized, dried and concentrated. The residue was dissolved in 250 mlethyl acetate and the solution was treated with carbon tetrachloride. The mixture was stirred several hours and then chilled. The solids were removed by filtration to give 68.5 g of (-)-threo-chlorocitric acid, mp 138-140, ra]D5 -6.60 (c, 2.0, H20). An additional 20.2 g of material were recovered from the mother liquors.
Example ?
(-)-Threo-epoxyaconitic acid monohydrate ( 105 g) was dissolved in 150 ml of water containing 43.0 ml conc.
hydrochloric acid. To the stirred solution 50 g of sodium chloride was added and the mixture was heated at 70 for 12 hours. The reaction was worked up as in example 6 to 25 give (+)-threo-chlorocitric acid in two crops:
crop 1: mp 138-140; ~a]~5 +6.65 (c, 2.0, H20); 55.2 g crop 2: mp 138-140; ~a]D5 +6.55 (c, 2.0, H20); 23.0 g.
Recrystallization of the solid from ethyl acetete-car-30 bon tetrachloride gave the analytically pure material, ~ mp 140.5-142; ~a]D5 +6.9 (c, 2.0, H20).
Example 8 A solution of 8.1 g (+)-erythro-epoxyaconitic acid 35 in 43 ml 1N hydrochloric acid containing 15 g sodium chlo-ride was heated at 78 for 25 minutes and an additional 20 minutes at 80. Evaporation of the solvent left a residue
Example ~
30 g of (+)-erythro-chlorocitric acid was dissolved in 175 ml of a methanol-water mixture (49:1). The solution was cooled to 15 and 39.5 g (-)-p-nitro-a-methylbenzyl-amine in 75 ml of the same methanol-water mixture was added. The mixture was stirred at room temperatur for 18 hours. The solids were collected by filtration and then washed with ethanol and ether to give 24.0 g of partially resolved (+)-erythro-chlorocitric acid-bis(-)-p-nitro-a-methylbenzylamine salt.
The impure salt was then split in the following manner:
hydrogen chloride gas was bubbled through a stirred sus-pension of finely divided salt (27.1 g) in ether for 30 minutes. The resulting solid (-)-p-nitro-a-methylbenzyl-amine hydrochloride (19.9 g, mp 247-249) was removed 20 by filtration and the filtrate was concentrated to give 10.9 g of partially resolved (+)-erythro-chlorocitric acid a~ an oil (65 o/o optical purity).
The (-)-p-nitro-a-methylbenzylamine hydrochloride 25 was partitioned between dichloromethane and 1N sodium hydroxide. The amine recovered from this process (1~.6 g) in 40 ml methanol-water (49:1) was added to a solution of the crude (+)-erythro-chlorocitric acid in 40 ml metha-nol-water (49:1) and the mixture, after stirring, deposi-30 ted 18.1 g of enriched bis-amine chlorocitrate.
The salt was again split using ethereal hydrogen chlo-ride and was then reformed in the manner described above.
This gave 14.4 g of the bis-amine chlorocitrate. The (+)-35 erythro-chlorocitric acid recovered from the latest salt was recrystallized from ethyl acetate-carbon tetrachloride to give 4.3 g of material (29 o/o chemical yield) which 1~38~7() was 85 o/o optically pure.
The mother liquors of the solution of the partially resolved (+)-erythro-chlorocitric acid-bis(-)-p-nitro-a-methylbenzylamine salt were treated with 13 ml of conc.hydrochloric acid and evaported. 1,2-Dimethoxyethane was added and the ~olution was evaporated to dryness. Ether was added to the residue, the mixture was stirred and the precipitate was collected to afford 29.2 g of (-)-p-10 nitro-a-methylbenzylamine hydrochloride.
The filtrate was concentrated to dryness and the resi-due, rich in (-)-erythro-chlorocitric acid, was dissolved in 90 ml of methanol-water (49:1). A solution of 25.3 g 15 of (+)-p-nitro-a-methylbenzylamine and 50 ml of methanol-water (49:1) was added. The resulting mixture was stirred for 20 hours and the precipitate was collected to afford 15.0 g of bis-(+)-p-nitro-a-methylbenzylamine salt en-riched in (-)-erythro-chlorocitric acid. The salt was 20 suspended in 185 ml of ether and hydrogen chloride was added to the suspension. The precipitated (+)-p-nitro-a-methylbenzylamine hydrochloride (10.7 g) was collected on a filter. The filtrate was concentrated to dryness and the residue was dissolved in 40 ml of methanol-water (49:1). To the methanol-water solution was added a solu-tion of 8.9 g of (+)-p-nitro-a-methylbenzylamine and 15 ml of methanol-water (49:1) and the solution was stirred for 2.5 hours. The precipitate (11.75 g) enriched in (-)-erythro-chlorocitric acid-bis-(+)-p-nitro-a-methylbenzyl-30 amine salt, was suspended in ether and the resulting sus-pension was saturated with hydrogen chloride. The preci-pitated (+)-p-nitro-a-methylbenzylamine hydrochloride (8.o9 g) was collected and the filtrate was concentrated.
Recrystallization of the residue from ethyl acetate-car-35 bon tetrachloride gave 3.9 g of (-)-erythro-chlorocitric acid (85 o/o optical purity).
.
' ~
'.
~3~4~0 Example 6 10S g (+)-threo-epoxyaconitic acid monohydrate was dissolved in 150 ml of water containing 43 ml conc. hy-drochloric acid. Sodium chloride (50 g) was added to the ~; stirred solution and the mixture was heated at 70 for 12 hours. The solution wa3 evaporated to dryness and the residue was triturated with 400 ml ethyl acetate. The mixture was filtered and the filtrate was decolorized, dried and concentrated. The residue was dissolved in 250 mlethyl acetate and the solution was treated with carbon tetrachloride. The mixture was stirred several hours and then chilled. The solids were removed by filtration to give 68.5 g of (-)-threo-chlorocitric acid, mp 138-140, ra]D5 -6.60 (c, 2.0, H20). An additional 20.2 g of material were recovered from the mother liquors.
Example ?
(-)-Threo-epoxyaconitic acid monohydrate ( 105 g) was dissolved in 150 ml of water containing 43.0 ml conc.
hydrochloric acid. To the stirred solution 50 g of sodium chloride was added and the mixture was heated at 70 for 12 hours. The reaction was worked up as in example 6 to 25 give (+)-threo-chlorocitric acid in two crops:
crop 1: mp 138-140; ~a]~5 +6.65 (c, 2.0, H20); 55.2 g crop 2: mp 138-140; ~a]D5 +6.55 (c, 2.0, H20); 23.0 g.
Recrystallization of the solid from ethyl acetete-car-30 bon tetrachloride gave the analytically pure material, ~ mp 140.5-142; ~a]D5 +6.9 (c, 2.0, H20).
Example 8 A solution of 8.1 g (+)-erythro-epoxyaconitic acid 35 in 43 ml 1N hydrochloric acid containing 15 g sodium chlo-ride was heated at 78 for 25 minutes and an additional 20 minutes at 80. Evaporation of the solvent left a residue
3~14 consisting of crude (-)-erythro-chlorocitric acid and sodium chloride. The organic material was dissolved in glyme and the resulting solution was filtered to remove sodium chloride, dried and concentrated. Crystallization of the product from ethyl acetate-carbon tetrachloride afforded 7.4 g of essentially pure (-)-erythro-chloro-citric acid. Recrystallization furnished 5.4 g of pure acid, mp 133.5-135; [a~D5 -2.2 (c, 2.0, H20).
Exam_le 9 (-)-Erythro-epoxyaconitic acid (9.~ g) was converted into 7.6 g of (+)-erythro-chlorocitric acid (mp 132-134) by a procedure essentially identical to that described in example 8. Recrystallization of the chlorocitric acid thus obtained afforded 5.3 g of analytically pure mate-rial, mp 133.5-135; [~]D- +2.2 (c, 2.0, H20).
Example 10 Trans-aconitic acid (87.0 g) was added portionwise to a solution of 60.0 g of sodium hydroxide in 200 ml of water. The mixture was cooled and chlorinated as in Example 1. The resulting solution of (+)-threo-chloro-25 citric acid-B-lactone disodium salt (purged free of excess chlorine gas) was cooled to -10 and treated with 40.0 g sodium hydroxide. The solution was stirred and the reac-tion temperature was moderated by cooling so that it did not exceed 20. The mixture was stirred at 20 for 20 30 minutes and then 42 ml of conc. sulfuric acid was added dropwise with cooling. The solution was extracted with diethyl ether. The ether extract was dried and concentra-ted. The resulting solid was crystallized from ethyl ace-tate-carbon tetrachloride to give 67.8 g of (+)-threo-35 epoxyaconitic acid, mp 169-172. A second crop (8.85 g;
mp 167-170) was collected from the mother liquors.
:, , .
--- 113F~470 - 24 _ Example 11 Tablets with the following composition were prepared:
Amount (mg/tablet) ~ threo-chlorocitric acid 50 polyvinylpyrrolidone 2 microcrystalline cellulose 10 silicone dioxide 10 magnesium stearate '
Exam_le 9 (-)-Erythro-epoxyaconitic acid (9.~ g) was converted into 7.6 g of (+)-erythro-chlorocitric acid (mp 132-134) by a procedure essentially identical to that described in example 8. Recrystallization of the chlorocitric acid thus obtained afforded 5.3 g of analytically pure mate-rial, mp 133.5-135; [~]D- +2.2 (c, 2.0, H20).
Example 10 Trans-aconitic acid (87.0 g) was added portionwise to a solution of 60.0 g of sodium hydroxide in 200 ml of water. The mixture was cooled and chlorinated as in Example 1. The resulting solution of (+)-threo-chloro-25 citric acid-B-lactone disodium salt (purged free of excess chlorine gas) was cooled to -10 and treated with 40.0 g sodium hydroxide. The solution was stirred and the reac-tion temperature was moderated by cooling so that it did not exceed 20. The mixture was stirred at 20 for 20 30 minutes and then 42 ml of conc. sulfuric acid was added dropwise with cooling. The solution was extracted with diethyl ether. The ether extract was dried and concentra-ted. The resulting solid was crystallized from ethyl ace-tate-carbon tetrachloride to give 67.8 g of (+)-threo-35 epoxyaconitic acid, mp 169-172. A second crop (8.85 g;
mp 167-170) was collected from the mother liquors.
:, , .
--- 113F~470 - 24 _ Example 11 Tablets with the following composition were prepared:
Amount (mg/tablet) ~ threo-chlorocitric acid 50 polyvinylpyrrolidone 2 microcrystalline cellulose 10 silicone dioxide 10 magnesium stearate '
Claims (14)
1. A process for the manufacture of citric acid deri-vatives of the formula Ia and of corresponding threo-.alpha.-lactones of the formula Ib as well as of pharmaceutically acceptable salts thereof comprising a) for the preparation of a (+)-threo-lactone of formula Ib contacting an aqueous solution of a tri-alkali metal salt or tri-alkaline earth metal salt of cis- or trans-aconitic acid with chlorine or hypochlorous acid and contacting the obtained salt of (+)-threo-chlorocitric acid-.beta.-lactone of the formula _ 26 _ Ib 1 wherein M is an alkali or alkaline earth metal, with an acid, b) for the preparation of (+)-threo-chlorocitric acid of the formula Ia 1 hydrolysing a compound of formula Ib or Ib1, c) for the preparation of a compound of formula Ia clea-ving epoxyaconitic acid with an alkali metal chloride or alkaline earth metal chloride in an aqueous solvent in the presence of an acid, d) for the preparation of (+)-erythro-chlorocitric acid of the formula Ia 2 cleaving a compound of the formula II
wherein M' is an alkali metal and R is hydrogen or M', with an alkali metal chloride in an aqueous solvent in the presence of an acid, e) resolving an obtained (+)-threo-citric acid deri-vative of formula Ia or Ib or (+)-erythro-citric acid derivative of formula Ia into its optically active anti-podes and isolating a desired antipode, f) if desired isolating an obtained compound of formula Ia or Ib in form of a pharmaceutically acceptable salt thereof.
wherein M' is an alkali metal and R is hydrogen or M', with an alkali metal chloride in an aqueous solvent in the presence of an acid, e) resolving an obtained (+)-threo-citric acid deri-vative of formula Ia or Ib or (+)-erythro-citric acid derivative of formula Ia into its optically active anti-podes and isolating a desired antipode, f) if desired isolating an obtained compound of formula Ia or Ib in form of a pharmaceutically acceptable salt thereof.
2. A process according to claim 1, wherein (+)-threo-epoxyaconitic acid affords (+)-threo-chlorocitric acid.
3. A process according to claim 1, wherein (+)-erythro-epoxyaconic acid affords (+)-erythro-chlorocitric acid.
4. A process according to claim 1, wherein (+)-threo-epoxyaconitic acid affords (-)-threo-chlorocitric acid.
5. A process according to claim 1, wherein (-)-threo-epoxyaconitic acid affords (+)-threo-chlorocitric acid.
6. A process according to claim 1, wherein (-)-erythro-epoxyaconitic acid affords (+)-erythro-chloro-citric acid.
7. A process according to claim 1, wherein (+)-erythro-epoxyaconitic acid affords (-)-erythro-chloro-citric acid.
8. Compounds of formula Ia or Ib according to claim 1 and pharmaceutically acceptable salts thereof, whenever prepared by the process as claimed in any one of claim 1 or by an obvious chemical equivalent thereof.
9. (?)-Threo-chlorocitric acid and pharmaceutically acceptable salts thereof, whenever prepared by the process of claim 2 or by an obvious chemical equivalent thereof.
10. (?)-Erythro-chlorocitric acid and pharmaceutically acceptable salts thereof, whenever prepared by the process of claim 3 or by an obvious chemical equivalent thereof.
11. (-)-Threo-chlorocitric acid and pharmaceutically acceptable salts thereof, whenever prepared by the process of claim 4 or by a chemical equivalent thereof.
12. (+)-Threo-chlorocitric acid and pharmaceutically acceptable salts thereof, whenever prepared by the process of claim 5 or by an obvious chemical equivalent the-reof.
13. (+)-Erythro-chlorocitric acid and pharmaceuti-cally acceptable salts thereof, whenever prepared by the process of claim 6 or by an obvious chemical equi-valent thereof.
14. (-)-Erythro-chlorocitric acid and pharmaceuti-cally acceptable salts thereof, whenever prepared by the process of claim 7 or by an obvious chemical equi-valent thereof.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/973,504 US4312885A (en) | 1978-12-26 | 1978-12-26 | Chlorocitric acids |
| CH10580/79 | 1979-11-28 | ||
| CH1058079 | 1979-11-28 | ||
| US973,504 | 1992-11-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1138470A true CA1138470A (en) | 1982-12-28 |
Family
ID=25706941
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000342235A Expired CA1138470A (en) | 1978-12-26 | 1979-12-19 | Citric acid derivatives |
Country Status (16)
| Country | Link |
|---|---|
| EP (1) | EP0016867B1 (en) |
| AR (1) | AR222201A1 (en) |
| AU (1) | AU527139B2 (en) |
| CA (1) | CA1138470A (en) |
| DE (1) | DE2965783D1 (en) |
| DK (1) | DK154641C (en) |
| ES (2) | ES487247A0 (en) |
| FI (1) | FI67073C (en) |
| HU (1) | HU179987B (en) |
| IE (1) | IE49341B1 (en) |
| IL (1) | IL59015A (en) |
| MC (1) | MC1299A1 (en) |
| NO (1) | NO153491C (en) |
| NZ (1) | NZ192423A (en) |
| PH (1) | PH14915A (en) |
| PT (1) | PT70628A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT500800B1 (en) | 2004-09-08 | 2008-07-15 | Biomedica Medizinprodukte Gmbh | PROCESS FOR DETERMINING PROBNP |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3356721A (en) * | 1962-03-21 | 1967-12-05 | Richard H Wiley | Citric acid manufacture |
| US3764692A (en) * | 1970-09-30 | 1973-10-09 | Hoffmann La Roche | Method of treating obesity |
| US3901915A (en) * | 1973-10-10 | 1975-08-26 | Hoffmann La Roche | Optical resolution of organic carboxylic acids |
| US4123458A (en) * | 1975-12-22 | 1978-10-31 | Lever Brothers Company | Preparation of cis and trans aconitic acids and their salts |
-
1979
- 1979-12-17 NZ NZ192423A patent/NZ192423A/en unknown
- 1979-12-18 FI FI793976A patent/FI67073C/en not_active IP Right Cessation
- 1979-12-19 CA CA000342235A patent/CA1138470A/en not_active Expired
- 1979-12-19 AU AU54009/79A patent/AU527139B2/en not_active Ceased
- 1979-12-19 MC MC791421A patent/MC1299A1/en unknown
- 1979-12-20 IL IL7959015A patent/IL59015A/en unknown
- 1979-12-21 DE DE7979105314T patent/DE2965783D1/en not_active Expired
- 1979-12-21 NO NO79794232A patent/NO153491C/en unknown
- 1979-12-21 PT PT70628A patent/PT70628A/en unknown
- 1979-12-21 DK DK554079A patent/DK154641C/en not_active IP Right Cessation
- 1979-12-21 IE IE2501/79A patent/IE49341B1/en unknown
- 1979-12-21 EP EP79105314A patent/EP0016867B1/en not_active Expired
- 1979-12-21 PH PH23453A patent/PH14915A/en unknown
- 1979-12-21 HU HU79HO2203A patent/HU179987B/en not_active IP Right Cessation
- 1979-12-24 ES ES487247A patent/ES487247A0/en active Granted
-
1980
- 1980-06-25 ES ES492727A patent/ES8105252A1/en not_active Expired
- 1980-10-26 AR AR279443A patent/AR222201A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| IL59015A (en) | 1983-10-31 |
| IE792501L (en) | 1980-06-26 |
| NZ192423A (en) | 1981-12-15 |
| FI793976A (en) | 1980-06-27 |
| AR222201A1 (en) | 1981-04-30 |
| DK554079A (en) | 1980-06-27 |
| ES492727A0 (en) | 1981-06-01 |
| ES8105252A1 (en) | 1981-06-01 |
| ES8100243A1 (en) | 1980-11-01 |
| EP0016867B1 (en) | 1983-06-22 |
| MC1299A1 (en) | 1980-10-03 |
| PH14915A (en) | 1982-01-29 |
| ES487247A0 (en) | 1980-11-01 |
| DK154641C (en) | 1989-05-08 |
| HU179987B (en) | 1983-01-28 |
| PT70628A (en) | 1980-01-01 |
| NO153491C (en) | 1986-04-02 |
| IE49341B1 (en) | 1985-09-18 |
| AU527139B2 (en) | 1983-02-17 |
| FI67073C (en) | 1985-01-10 |
| NO794232L (en) | 1980-06-27 |
| DK154641B (en) | 1988-12-05 |
| EP0016867A1 (en) | 1980-10-15 |
| NO153491B (en) | 1985-12-23 |
| IL59015A0 (en) | 1980-03-31 |
| DE2965783D1 (en) | 1983-07-28 |
| FI67073B (en) | 1984-09-28 |
| AU5400979A (en) | 1980-07-03 |
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