HU181911B - Process for preparing alpha-fluoromethyl-alpha-amino-alkane-carboxylic acids and esters thereof - Google Patents

Abstract

The invention relates to a process for the preparation of o-fluoromethyl-α-aminoalkanoic acid of the general formula (I). The compounds prepared according to the invention have decarboxylase-inhibiting activity and are suitable for physiological and chemotherapeutic purposes, for example, for the treatment of Parkinson's, Schen's disease .or also as diagnostic aids for functional testing of biological systems = c. Fluoromethyl-α-aminoalkaric acids are prepared according to the invention, for example, by esterification of a compound of the Forrael. In the formulas, R 1 is H or C 1 -C -alkyl and R is, for example a substituted C "" € 4-alkyl group or a compound such as formula (III). Formulas I to III

Description

A process for the preparation of α-fluoromethyl-α-aminoalkane carboxylic acids and their esters

The present invention relates to novel substituted α-fluoromethyl-α-aminoalkane carboxylic acids and their esters. These novel compounds have valuable biological activity, including the ability to inhibit, inter alia, decarboxylase.

J. Org. Chem., 40, 3808-3809 (1975), has already become known as an unsubstituted α-fluoromethyl-α-aminoalkane carboxylic acid, namely 2-fluoromethylalanine of formula VI. However, it is not mentioned in this literature that this compound has any biological activity. Otherwise, the compound can be prepared by fluorodehydroxylation of 2-hydroxymethylalanine.

U.S. Patent No. 737,907 to Goodman et al., Entitled "The Pharmacological Basis of Therapeutics". 577 (published in 1970 by the MacMillan Company, New York publisher), it is known that α-methyl amino acids such as La-methyl-3,4-dihydroxyphenylalanine (amethyl dopa, an antihypertensive drug) inhibit decarboxylase.

It has been found that the racemic or optically active compounds of the formula I wherein

R is 3,4-dihydroxybenzyl, 4-hydroxybenzyl, 3-hydroxybenzyl, 3-aminopropyl, 2-carboxyethyl, imidazol-4-ylmethyl, indole. 3-ylmethyl or 3- (1-guanidyl) propyl, and

R 1 is hydrogen or C 1-4 alkyl, and their pharmaceutically acceptable acid addition salts are inhibitors of decarboxylase enzymes and are significantly better than α-methylamino acids.

The compounds of formula I may form pharmaceutically acceptable acid addition salts with inorganic or organic acids. Inorganic acids which may be used in the salt formation are preferably hydrogen halides, such as hydrochloric acid, hydrogen iodide or hydrobromic acid, sulfuric acid and phosphoric acids. Most preferred is the formation of salts with halohydrocarbons, in particular hydrochloride.

The compounds of formula I have a chiral center and thus may exist in the form of optically active forms, i.e. optical isomers. These isomers may be conventionally designated by the symbols L and D, (+) and (-), 1 and d, S and R, or combinations thereof. Where no isomer is mentioned in the name or formula of a compound, the name or formula refers to the individual isomers or mixtures of isomers and racemates.

Compounds having the S-isomeric configuration are considered to be most preferred.

As mentioned, R 1 is hydrogen or C 1-4 alkyl. Examples of the latter include methyl or ethyl. Most preferred for R _t is hydrogen.

A further preferred group of compounds of Formula I are those compounds of Formula ΠΙ, wherein R 1 is as defined above, and of which R 1 is hydrogen.

A preferred compound of formula I is the compound of formula IX, X, XH or XIII.

The compounds of the invention have physiological or chemotherapeutic activity. In most cases, these compounds have a

The biological activity of -1181911 is due to their highly potent decarboxylase inhibitory activity. Decarboxylases are enzymes that, when exposed to α-amino acid substrates, induce their decarboxylation to the corresponding amines according to the following equation:

L-CH-CO ₂ H ---- decarboxylase-L-CH ₂ -NH ₂

NH ₂ wherein L is alkyl or aralkyl.

By inhibiting this decarboxylation process, many biosynthetic pathways leading to biologically significant amines can be modified or inhibited with physiologically relevant consequences. For example, α-fluoromethyl dopa inhibits dopa decarboxylase and can thus be used in combination with dopa to potentiate the effect of the latter against Parkinson's disease. Α-Fluoromethyl-histidine inhibits histamine biosynthesis by inhibiting the decarboxylation of histidine (ED _J0 value in mouse is approximately 0.4 mg / kg). Consequently, this compound, or combinations with other histamine antagonists, can be used to prevent gastric damage and to treat allergic symptoms. Because of its inhibitory effect on omitin decarboxylase, α-fluoro-methyl-omitin interrupts the biosynthesis of polyamines and can thus be used to treat certain cancers. Α-Fluoromethyl-arginine is a potent antimicrobial agent, while α-Fluoromethyl-glutanic acid has a sedative effect on the central nervous system.

However, the compounds of the present invention are substantially specific for their inhibitory effect on decarboxylase enzymes in that an α-fluoromethyl-α-aminoalkane carboxylic acid inhibits the decarboxylation of the corresponding non-α-fluoromethyl-containing amino acid. For example, α-fluoronetU-dopa inhibits the decarboxylation of dopa, while α-fluoro-methyl-histidine inhibits the decarboxylation of histidine. The dosage of the compounds of the formula I for such use is 0.5 to 25.0 g per day by oral administration to humans.

Because of their specificity and efficacy as a decarboxylase inhibitor, the compounds of the present invention can also be used as diagnostic tools to detect appropriate decarboxylases and to determine their importance or role in the functioning of both diseases and biological systems. For example, the importance of γ-aminobutyric acid in the function of the central nervous system can be studied by inhibiting its biosynthesis by using α-fluoromethylglutamic acid. Thus, this diagnostic utility is made possible by the effective and in most cases irreversible decarboxylase inhibitory activity of the a-fluoromethyl amino acids of the invention.

Conventional in vitro experiments have demonstrated the inhibitory effect of some compounds of formula I on the decarboxylase.

Among the compounds of formula I, α-fluoromethyl-3,4-dihydroxyphenylalanine, α-fluoromethyl-tyrosine and α-fluoromethyl-metatyrosine also have antihypertensive activity. This effect was determined by observing an antihypertensive effect in spontaneously hypertensive rats (so-called SH) when the test compounds were administered orally or parenterally. The observed effect indicates that these compounds, when administered in the appropriate dosage in the form of a suitable pharmaceutical composition, are effective antihypertensive agents in man. Said pharmaceutical compositions may be prepared in conventional manner with conventional pharmaceutical carriers and / or excipients.

The compounds of formula I may be prepared by methods well known in the art of organic chemistry.

Most preferably, the reaction is carried out by reacting an α-hydroxymethyl-α-amino acid with sulfur tetrafluoride in liquid hydrogen fluoride as shown in Scheme A. The reaction is usually carried out at a temperature between -80 'C and +20' C. This reaction is also called fluoride dehydroxylation and is described in the Journal of Organic Chemistry, 40, 3809-3810 (1975). Boron trifluoride may be used to accelerate the reaction.

However, it has been found that fluorine hydroxylation of certain aryl-substituted α-hydroxymethyl-α-amino acids can be substantially facilitated by the use of boron trifluoride or aluminum trichloride as co-reactants with sulfur tetrafluoride. Compounds of formula IV, wherein R 'is one of the aryl groups listed above, can thus be prepared in a very advantageous manner by reaction of a compound of formula V, wherein R' is as defined above, with sulfur tetrafluoride and boron trifluoride or aluminum chloride. in liquid hydrogen fluoride at temperatures between -80 ° C and 20 ° C.

R 'is thus 3,4-dihydroxyphenyl, 4-hydroxyphenyl, 3-hydroxyphenyl, indol-3-yl, or 2H-imidazol-2-yl. Preferably R 'is 3,4-dihydroxyphenyl, 4-hydroxyphenyl or imidazol-4-yl.

The reaction is preferably carried out at atmospheric pressure, although pressures higher than atmospheric may be employed. Preferably, the reaction is carried out at a temperature between -80 'C and 0' C.

The reaction may be carried out simply by adding the total amount of sulfur tetrafluoride and boron trifluoride or aluminum trichloride used at the beginning of the reaction to the reaction mixture consisting of the starting compound V and liquid hydrogen fluoride, or it may be possible to first react with sulfur. tetrafluoride is added to the reaction mixture and the reaction is allowed to proceed for a defined period of time, then boron trifluoride or aluminum trichloride is added and the reaction mixture is left to react until the reaction is complete.

The use of boron trifluoride or aluminum chloride significantly increases the yield of the final products of formula IV.

Another method for the preparation of substituted α-fluoromethyl-α-aminoalkanecarboxylic acids is photofluorination. This method is described in the Journal of the American Chemical Society, 92,7494 (1970) and ibid, 98,5591 (1976). For example, α-fluoromethylglutamic acid can be prepared by photofluorination of α-methylglutamic acid. Both optical isomers of α-methylglutamic acid are known, so this method can be used to prepare both isomers of α-fluoromethylglutamic acid.

Similarly, α-fluoromethyl omitin can be prepared by photofluorination of α-methyl ornithine. Given that both optical isomers of α-methyl omitin are accessible, this method allows the production of both optical isomers of α-fluoromethyl ornithine.

In addition, α-fluoromethyl omitin can be used to produce α-fluoromethyl arginine by reaction with S-methyl isothiourea.

The acid addition salts of the compounds of formula I are prepared in conventional manner, i.e. by treating the free α-amino acid with a suitable acid in a suitable solvent.

A single enantio-21819 * 1 of a compound of formula I may be prepared by resolution of the corresponding racemate in a manner known per se, or by resolution of the a-hydroxymethyl-a-amino acid used as the starting material, followed by fluorodehydroxylation of the resulting enantiomer. . For example, the resolution is carried out in a manner known per se by preparing the salt of the α-amino acid with an optically active base and then liberating the enantiomer to be isolated from the salt.

The compounds R ₁ is C 1-4 alkyl bearing formula I compound with a hydrogen atom to the corresponding formula I where Ri is a per se known manner by esterification obtained.

The invention is illustrated by the following examples. Fluorohydroxylation reactions were carried out in reactors made of "KEL-F" material. The melting points given below were determined in open capillary tubes. The values you provided are not corrected.

Example 1

Preparation of R, S-α-fluoromethyl-3-hydroxytyrosine

While cooling in a bath of dry ice and acetone, 1.5 g of R, S-hydroxymethyl-3-hydroxytyrosine hydrochloride (a-hydroxymethyldopa hydrochloride) were dissolved in 50 ml of anhydrous hydrogen fluoride, and after removal of the cooling bath, the hydrogen was removed. -fluoride is evaporated by passing nitrogen gas. As a result of this step, the hydrochloride salt of the starting compound is converted to the hydrofluoride salt. (Alternatively, 1.3 g of the free amino acid may be used as a starting material, which may of course be omitted.) The resulting hydrofluoride salt is then redissolved by introducing hydrogen fluoride gas into the reactor while cooling in a bath of dry ice and acetone. it contains 30 ml of liquid hydrogen fluoride. Sulfur tetrafluoride gas (volume - 1.2 ml, measured at 78 ° C in a liquid state) was then introduced into the reactor, and the cooling bath was removed and replaced with a cooling bath at -12 ° C. The reaction mixture was allowed to stand for 15 hours, then the solvent was evaporated by passing nitrogen and the residue was dissolved in 50 ml of 2.5N aqueous hydrochloric acid. The resulting solution was then concentrated in vacuo and the residue subjected to amino acid analysis using a Spinco-Beckman analyzer. Analysis shows that α-fluoromethyl-3-hydroxytyrosine is formed. The desired title compound is isolated by ion exchange chromatography as described in Example 2 below for the isolation of S-α-fluoromethyl-3-hydroxytyrosine.

Example 2

Methylation by converting S-α-fluoromethyl-3-hydroxytyrosmole to 3- (3 ', 4'-dimethoxyphenyl) -2-acetamino-2-hydroxymethylpropionic acid. This operation was carried out by dropwise addition of about 64 ml of dimethyl sulfate and about 148 ml of 4 M aqueous potassium hydroxide solution over 1 hour at room temperature under vigorous stirring under nitrogen.

The reaction mixture was stirred for 1 hour after the addition was complete and allowed to stand overnight. thereafter

After acidification at 5-10 ° C with 55 ml of concentrated aqueous hydrochloric acid, the mixture is extracted 12 times with 300-300 ml of ethyl acetate. The combined extracts were dried over sodium sulfate and evaporated in vacuo to give R, S-3- (3 ', 4'-dimethoxyphenyl) -2-acetamino-2-hydroxymethylpropionic acid. The product is then purified by recrystallization from 1325 ml of acetonitrile to give a melting point of 154-156 ° C (dec.).

29.1 g of strychnine is suspended in 1.12 L of refluxed ethanol (2BA) and 26.1 g of R, S-3- (3 ', 4'-dimethoxyphenyl) -2- is added to the suspension. acetamino-2-hydroxymethylpropionic acid is added. The solution was cooled and allowed to stand at room temperature overnight. At this point, the strichnine salt of Antimer A, m.p. 193-194 'C, crystallizes out.

After separation of the crystals, the mother liquor was evaporated to dryness under vacuum and then recrystallized from 270 ml of ethanol (quality 2BA) by cooling the hot ethanol solution to room temperature and leaving it in the refrigerator for about 3 hours and then for 4 hours. The precipitated crystals are filtered off and, after drying, recrystallized from 30 acetonitrile to give 17.5 g of the strichnine salt of Antimer B, m.p. 130-132 ° C.

17 g of the latter strychnine salt was decomposed by first dissolving it in 160 ml of water and adding 31 ml of a 35 M aqueous sodium hydroxide solution. The precipitated strichnine was filtered off, and the resulting solution was concentrated in vacuo to a small volume and then applied to a small column of ion exchange resin (150 mL of Dowex 50 cation exchange resin AG-X2, 200/400 mesh particle size). The fractions showing absorption in a UVICORD 11-8300 UV spectrophotometer were then eluted with water. This yields Antimer B itself, which has a [α] _D = 78.3 ± 0.5 '(c = 1.425%, 0.1 M aqueous sodium hydroxide solution).

This antimony B is then converted to the corresponding stereoisomer of α-hydroxymethyl-3-hydroxytyrosine by first dissolving 4.43 g of antimony B in 100 ml of concentrated hydrochloric acid and pouring the resulting solution into a Fischer bomb tube. the bomb tube was sealed and kept in a 130 ° C oil bath for 90 minutes. The solvent was then evaporated in vacuo and the hydrochloric acid treatment repeated. The residue thus obtained is R-α-hydroxymethyl-3-hydroxytyrosine hydrochloride.

a) Preparation of R-α-hydroxymethyl-3-hydroxytyrosine

b) Fluorohydroxylation

To a stirred solution of 4M aqueous potassium hydroxide solution (204 ml) was added 50 g of 3- (3 ', 4'-diacetoxyphenyl) -2-acetamino-2-acetoxymethylpropionic acid. After stirring under nitrogen for 1 hour, the resulting solution contains the potassium salt of 3- (3 ', 4'-dihydroxyphenyl) -2-acetamino-2-hydroxymethylpropionic acid, which is formed in essentially quantitative yield. This compound was isolated without dimethylsulfate ₆₅

8 g of compound (b) obtained in step a) are immersed in a 1 liter reactor and the reactor is immersed in a bath of dry ice and acetone and condensed with 80 ml of liquid hydrogen fluoride. In order to remove the hydrogen chloride present, the cooling bath is removed, and the hydrogen fluoride solvent is evaporated by passing nitrogen gas through. The reactor was then immersed in the cooling bath again

Hydrogen fluoride gas is passed through the reactor until approximately 250 ml of liquid is collected. Then, 6.2 ml of sulfur tetrafluoride gas (17.6 mmol / ml, or nearly 109 mmol in total) were bubbled into the reactor and the reaction mixture was allowed to stand for 1 hour and then cooled in an ethylene glycol cooler at -16 ° C. bathing. For the latter, the reaction mixture was allowed to stand for approximately 22 hours, then boron trifluoride gas was passed through the reaction mixture until saturation and then allowed to stand at -16 ° C again for 46 hours. The cooling bath is then removed and the reaction mixture is concentrated by passing nitrogen gas at high speed. The residue was ice-cold 100 ml

Quench with 2.5 M aqueous hydrochloric acid, evaporate in vacuo and apply the residue to a column of 2.2 L AG-50-X-8 (200/400 mesh) cation exchange resin. The elution was first carried out with 0.25 M aqueous hydrochloric acid containing 5% (v / v) methanol, pumping through the column 7.2 liters of such solution over approximately 8.5 hours. Then, 7.2 liters of 0.4 M aqueous hydrochloric acid containing 7.5 volumes of methanol was finally passed through the column over a period of 8.5 hours, followed by the addition of 0.6 M aqueous hydrochloric acid containing 10 volumes of methanol. 22 ml fractions were collected and 10 to 10 sampling tubes were used per crab. The desired compound is prepared as described in Examples 45-66. tubes in crayfish. Concentration in vacuo gave the desired compound as its hydrochloride salt.

To liberate the free amino acid, 4.826 g of the resulting salt were dissolved in 90 mL of isopropanol and the resulting solution was filtered through a pad of Celite. Propylene oxide (6.2 ml) was added to the filtrate, and the resulting suspension was allowed to stand at room temperature for 3.5 hours and then at about 5 ° C for a further 2.5 hours. The Sa-fluoromethyl-3-hydroxytyrosine thus formed is then filtered off, washed with isopropanol and dried in vacuo at 76 ° C overnight. The product obtained had a [α] _D = + 9.3 ± 0.5 '(c = 1.82%, 1: 1 mixture of trifluoroacetic acid and water).

Example 3

Preparation of R-α-fluoromethyl-3-hydroxytyrosine

To obtain the title compound, antimony "A" of 3- (3 ', 4'-dimethoxyphenyl) -2-acetamino-2-hydroxymethylpropionic acid, prepared as described in Example 2, was subjected to the steps described in Example 2 as well. below. This gave the title compound having a [α] _D = -9 ° (c = 2.5%, 1: 1 mixture of trifluoroacetic acid and water).

Example 4

Preparation of R, S-α-fluoromethyl tyrosine

1.05 g (0.005 mole) of R, S-α-hydroxymethyl tyrosine was charged into a reactor and the reactor was immersed in a bath of dry ice and acetone and condensed with 50 ml of hydrogen fluoride by passing hydrogen fluoride gas through it. With continuous cooling, sulfur tetrafluoride gas (measured at -78 'C at 4 ml in a liquid state) is then introduced and boron trifluoride gas is saturated at -78 C' (while stirring with magnetic stirrer). The resulting dark red solution was then allowed to stand at -78 ° C overnight, then the cooling bath was removed and the solvent was removed by purging with dry nitrogen gas. The residue was dissolved in 2.5 mL of 2.5 M aqueous hydrochloric acid and the resulting solution was evaporated to dryness in vacuo. The residue was then dissolved in water and applied to a column of highly acidic cation exchange resin prepared from 100 ml of AG 50-X-8, 200/400 mesh. The column was washed first with 1.8 L of water and then eluted with 0.5 M aqueous hydrochloric acid. Fractions of 20 ml are collected and the fractions are continuously analyzed with a UVICORD II UV spectrophotometer during elution. Fractions corresponding to the main peak in the ultraviolet spectrum were pooled and evaporated to dryness in vacuo to give the R, S-α-fluoromethyl-tyrosine hydrochloride salt. 400 horns of this salt were dissolved in 6 mL of water and after a few minutes the title compound began to crystallize. After standing overnight at 5 'C, the reaction mixture is filtered and the product filtered off is washed with water, ethanol and diethyl ether and finally dried at 76' C under vacuum.

Example 5

Preparation of R, S-α-fluoromethyl-histidine (Scheme B)

a) Preparation of racemic N (im) benzylhistidine

Dissolve 30 g of N (im) benzyl L-histidine in 600 ml of water and heat the resulting solution in a high pressure autoclave at 200 ° C for 8 hours with shaking. The autoclave is then cooled to room temperature and the pure supernatant liquid phase is separated off and evaporated to dryness in vacuo to give the corresponding racemate as colorless crystals.

b) R, S-α-hydroxymethyl-N (im) benzyl-

-histidine

Dissolve 20 g of the racemate obtained in step a) in 1 liter of hot water and add 40 g of basic copper (II) carbonate in small portions. The resulting mixture was then heated under reflux for 1 hour with stirring, and the mixture was filtered while the filtrate was concentrated in vacuo to give the racemic N (im) benzylhistidine copper chelate as a blue precipitate.

A mixture of 2 ml of formalin (38% formaldehyde solution), 3.1 ml of pyridine and 2.13 g of sodium carbonate was heated to 70 ° C with stirring, then 20 g of the chelate prepared as described in the previous paragraph was added. The reaction mixture was stirred at 75 ° C for 90 minutes and then concentrated in vacuo to give a blue precipitate. This was then dissolved in a mixture of water (50 mL) and concentrated ammonium hydroxide (50 mL) and applied to a column of cation exchange resin (300 mL of Dowex 50-X8 NH ₄ ) and eluted with 2M aqueous ammonium hydroxide. The eluate was examined with a UVICORD Type II UV spectrophotometer and the 1.1 L portion of absorbance was pooled and evaporated to dryness in vacuo. The residue was dissolved in a mixture of 60 ml of water and 5 ml of concentrated aqueous ammonium hydroxide solution and then applied from an anion exchange resin (300 ml of Dowex 1-X-2).

-4181911

OH-form) column. The column was washed with 2 liters of water and eluted with 2M aqueous hydrochloric acid, the eluate being examined with the aforementioned UV spectrophotometer. The absorbent fractions were combined and evaporated to dryness to afford the substantially pure hydrochloride salt of the new N (im) benzyl -? - hydroxymethyl histidine. This compound was then converted to α-hydroxymethyl histidine by dissolving 12.5 g of N (im) benzyl α-hydroxymethyl histidine in 200 ml of liquid ammonia in a round-bottomed flask equipped with a condensing unit containing a mixture of dry ice and acetone. then cut into small pieces of sodium metal (5.5 g) to give a blue color remaining for 10 minutes. Ammonium chloride is then added to the reaction mixture to consume excess metal sodium (indicated by the disappearance of color), and then the ammonia is allowed to evaporate under a stream of nitrogen gas. The product obtained is then purified by column chromatography on a column of cation exchange resin (Dowex 50-X-8, particle size 2.2, 200/400 mesh), which is dissolved in 100 ml of water and applied to the column. The column was then washed with 1 L of water and eluted first with 1.5 M hydrochloric acid and then with 2 M aqueous hydrochloric acid. Fractions of 20 ml were collected. The eluate had a flow rate of 600 ml / h.

Fraction Sequence Elution Pauli Reaction - 400 1.5M HCL 401-670 2M HCL

671 to 2 M HCL +

671-760. fractions were combined and evaporated to dryness in vacuo to give the new R, S-α-hydroxymethylhistidine dihydrochloride.

c) Dissolve 2.73 g of the compound obtained in step b) in R, Sa-fluoromethyl-histidine in ml of liquid hydrogen fluoride and evaporate to dryness under nitrogen. The residue thus obtained is the hydrofluoride salt of α-hydroxymethyl histidine. This salt was then redissolved in 200 mL of liquid hydrogen fluoride with cooling in a dry ice / acetone cooling bath and then fed with sulfur tetrafluoride (9 mL measured at -78 ° C in a liquid state). The reaction mixture was then allowed to stand overnight in a -12 ° C cooling bath, then saturated with boron trifluoride gas, allowed to stand for 5 hours, re-saturated with the same gas at -12 ° C, and allowed to stand again at the same temperature for 66 hours. forget it. The cooling bath was removed and the solvent was evaporated under a stream of nitrogen. The residue is primarily HBF ₄ salt of α-fluoromethyl-histidine. This salt is then 100 ml

Dissolve in 2.5 M aqueous hydrochloric acid, evaporate to dryness and convert to the hydrochloride salt as described below, redissolve in water and apply the resulting solution to a column of cation exchange resin (100 ml of AG 50-X-2, 200/400 mesh). apply and rinse the column with water until the wash liquid leaving the column is neutral or free of fluoride ions. The column was then eluted with 3M aqueous hydrochloric acid and the eluate evaporated to dryness in vacuo to give the substantially pure desired hydrochloride salt. For final purification, this salt is subjected to repeated chromatography on a new column of 900 ml of AG-50-X-2 resin, eluting with the following materials:

0.5 M aqueous hydrochloric acid solution - 1 liter

1.0 M aqueous hydrochloric acid solution - 1.5 liteT

1.5 M Hydrochloric Acid Solution - 3.3 L (Collect the eluate fractions here, taking 20 mL fractions) 2.0 M Hydrochloric Acid Solution - 8.0 L

Fractions containing the product were selected using the Pauly test. 390-470. fractions were combined and evaporated to dryness to afford the pure hydrochloride salt of the title compound. Recrystallization from 9: 1 isopropanol / water gave the crystalline monohydrochloride salt of the title compound, m.p. 226-227'C.

Example 6

Preparation of R, S-α-fluoromethyl omitin

a) R, S-α-hydroxymethyl-8-N-benzoyl omitin

With mechanical stirring at 70 ° C, a mixture of 12.45 ml of formalin (38% aqueous formaldehyde solution), 1.25 ml of pyridine and 0.81 g of sodium carbonate was added in small portions to 7.995 g of R, SN-benzoyl ornithine. Copper chelate was added and after stirring at the same temperature for 90 minutes, the reaction mixture was evaporated to dryness in vacuo. The resulting dark blue residue was dissolved in a mixture of 30 ml of water and 30 ml of concentrated aqueous ammonium hydroxide solution and applied to a column of cation exchange resin (130 ml of Dowex 50-X-8 resin in NH _{4 form} ) on copper (II). to remove ions. The column was eluted with 250 ml of 2M aqueous ammonium hydroxide solution and the eluate was evaporated to dryness in vacuo. The residue was redissolved in water and applied to a column of anion exchange resin (130 mL of Dowex 1-X-2 resin OH). The column was washed with 250 mL of water and eluted with 3M aqueous hydrochloric acid. The hydrochloric acid eluate was evaporated in vacuo to give the expected product.

b) R, S-α-hydroxymethyl omitine dihydrochloride was dissolved in 6 M aqueous hydrochloric acid (3.5 g) from the compound obtained in step (a), and the resulting solution was refluxed for 21 hours. The solution is then extracted twice with 40 ml of toluene (40 ml) and the aqueous phase is evaporated to dryness in vacuo to give the expected product which is otherwise a novel compound.

c) R, S-α-fluoromethyl omitin

A reactor was charged from the compound obtained in step b)

1.1 g and the reactor were immersed in a cooling bath of dry ice and acetone and flushed with hydrogen fluoride gas until 25 ml of liquid hydrogen fluoride were condensed. The cooling bath was removed and the solvent was evaporated under a stream of nitrogen. The residue is the hydrofluoride salt of R, S-α-hydroxymethyl ornithine. This residue is dissolved in 50 ml of liquid hydrofluoric acid from the hydrogen fluoride gas again in a refluxing bath and sulfur tetrafluoride gas (4 ml in a liquid state at 78 DEG C.) is introduced into the resulting solution. The bath of dry ice and acetone was then removed and a bath at -15 ° C

-5181911 bath. The reaction mixture was allowed to stand at -15 ° C for 16 hours and then boron trifluoride gas was passed through until saturated. The reaction mixture was allowed to stand for a further 5 hours, then the cooling bath was removed and the solvent was evaporated under a stream of nitrogen. The residue was dissolved in 6M aqueous hydrochloric acid and the resulting solution was concentrated in vacuo and redissolved in water (10 mL). This solution is then applied to a column of cation exchange resin (400 mL of Dowex 50-X-8 resin in H ^{+ form,} 200/400 mesh). The column was washed first with water (800 mL) and eluted with 2M aqueous hydrochloric acid (15 mL fractions). The flow rate is 600 ml / h. One drop of each fifth fraction was applied to a thin layer chromatography plate and developed with ninhydrin spray. A171-220. fractions were combined and evaporated to dryness in vacuo to give a mixture of amino acids based on R, 5-fluoromethyl-omitine dihydrochloride. For further purification purposes, this product was rechromatographed on another column of Dowex 50-X-8 cation exchange resin, 200/400 mesh. The column is washed first with water and then with a flow rate of 0.61 / hour

Elute with 1.5 M aqueous hydrochloric acid in 20 mL fractions. 521-540. fractions were evaporated to give the title compound.

Example 7

Preparation of S-α-fluoromethyl tyrosine

(a) Preparation of copper chelate of tyrosine methyl ether At 25 ° C, 25 g (128 mmol) of R, S-tyrosine methyl ether are dissolved in 646 ml of 0.2 N sodium hydroxide solution, and 16.1 g of gr. II) A solution of sulfate pentahydrate in 1600 mL of water was added. A precipitate formed immediately. The precipitated mixture was allowed to stand overnight and then filtered to give 28.9 g of copper chelate.

b) R, S-α-hydroxymethyl-tyrosine methyl ether

While stirring under nitrogen atmosphere at 70 ° C

To a mixture of 3.9 g of sodium carbonate, 52 ml of 37% aqueous formaldehyde solution and 5.2 ml of pyridine was added 29 g (0.064 mol) of the chelate obtained in step a). After the addition was complete, 18 ml of formaldehyde solution were added to the reaction mixture

Pyridine (1.6 ml) was added and the reaction mixture was heated at 70 ° C for 3.5 hours. The reaction mixture was then cooled to room temperature over 1.5 hours and then allowed to stand overnight at the same temperature. In the morning after standing, abundant amounts of blue crystals can be observed. The crystals were filtered off and the filtrate was evaporated to dryness in vacuo. The residue was then dissolved in water, then the aqueous solution was evaporated again and the resulting residue was dissolved in 90 ml of 4N hydrochloric acid. The resulting solution, after filtration, is used to dissolve the previously isolated blue crystals. A further 300 ml of 4N hydrochloric acid solution is required. The resulting solution was then treated with hydrogen sulfide, filtered through a pad of diatomaceous earth and evaporated to give approximately 40 g of crude product. This is then applied to a strongly acid cation exchange resin (0.5% Dowex 50-X-8), eluted with 4 L of water and then with 2 N aqueous ammonium hydroxide. The eluate was analyzed with a UV spectrophotometer UVICORDII and the absorbed fractions were concentrated in vacuo to give pure R, S-α-hydroxymethyltyrosine methyl ether (22.16 g).

c) R, S-N-acetyl-α-hydroxymethyl-tyrosine methyl ether

19.7 g (87.5 mmol) of the compound obtained in step b) are suspended in 200 ml of anhydrous pyridine, and 86 ml of acetic anhydride are added to the suspension. The resulting reaction mixture was allowed to stand at room temperature overnight, then evaporated to dryness in vacuo and then azeotroped with 2 x 50 mL of toluene. The residue was dissolved in a mixture of 118 ml of methanol and 130 ml of 2.5 N aqueous sodium hydroxide solution and the resulting mixture was stirred at room temperature for 3.5 hours. After acidification with 30 ml of concentrated hydrochloric acid solution, 200-

After extraction with 200 ml of ethyl acetate, the combined extracts are dried and evaporated to give 21 g of crude product. This was recrystallized from 75 ml of acetonitrile to give 9.35 g of R, S-N-acetyl-α-hydroxymethyl-tyrosine methyl ether, m.p. 151-152 ° C (dec.).

d) R, S-N-acetyl-α-hydroxymethyl tyrosine

optical resolution of methyl ether

Dissolve 10 g of the compound obtained in step c and 6.18 g of D-ephedrine in 50 ml of methanol, evaporate in vacuo and redissolve the residue in 50 ml of warm acetonitrile. The resulting crystallization gave 7.34 g of D-ephedrine salt of R-N-acetyl-a35-hydroxymethyl-tyrosine methyl ether, m.p. 125-131 C (batch A). Batch A is then recrystallized from 40 mL of acetonitrile to give 4.78 g of batch B, m.p. 130-134 'C. The mother liquors from Batches A and B were combined and evaporated, and the residue was dissolved in a mixture of 22.4 mL of 2.5N sodium hydroxide solution and 50 mL of water. The resulting aqueous solution was extracted with ethyl acetate (2 x 75 ml), cooled, acidified with concentrated hydrochloric acid (5 ml) and extracted with ethyl acetate (3 x 70 ml). The combined organic phases are dried and evaporated to give batch C (7.73 g). Batch C and 4.7 g L-ephedrine are dissolved in 50 ml methanol and evaporated to give batch D 12.39 g. This was then recrystallized from 50 mL of methanol to give 5.06 g of S-N-acetyl-α-hydroxymethyl-tyrosine methyl ester 131.5-

The L-ephedrine salt (batch E) with a melting point of 133.5 C is obtained. Batch E was recrystallized from 27 mL of acetonitrile

4.72 g of batch F of melting point 130.5-134,5 'C (dec.) Are obtained. The mother liquors from batches E and F were combined after concentration to give batch G of 7.31 g. Batch G is reconstituted to the free acid as described for batch C to give batch H of 3.0 g. This is then treated with 1.9 g of D-ephedrine as the starting material R, S. Recrystallization of the salt from 17 ml of acetonitrile gives 2.4 g of batch J, m.p. 127-130 ° C. Recrystallization of batch J yielded 2.06 g of batch K of melting point 130-134 'C (decomposed).

The B and K poles are recrystallized from 40 ml of acetonitrile after combining (total weight 65 6.52 g) to give 6.6 g

The yield of D-ephedrine salt of R-N-acetyl-α-hydroxymethyl-tyrosine methyl ether (75.8% overall) was -6181911.

The free acid is then liberated by converting the mother liquors from batches A and B to batch C to give 3.5 g of RN-acetyl-α-hydroxymethyl-tyrosine methyl ether having a rotation (a) of _D = +92 ° (c = 1.35%, 0.27 N sodium hydroxide solution).

e) R-α-hydroxymethyl tyrosine

Dissolve 3.3 g of the compound obtained in step d) in 100 ml of concentrated hydrochloric acid and keep the resulting solution in a tube at 130 ° C for 2 hours. The solution was evaporated to dryness and the residue was dissolved in water (35 mL), the aqueous solution was filtered and the filtrate was treated with 1 mL of pyridine to give 2.11 g (81%) of pure R-hydroxymethyl tyrosine. Rotation (α) _D = 0.86 ° (c = 1.15%, 50% aqueous trifluoroacetic acid). The so-called circular double-color spectrum (CD-spectrum) is the same as that of Sa-methyl tyrosine.

f) S-α-fluoromethyl-tyrosine

As described in Example 4, the compound obtained in this step can be converted to the title compound.

Example 8 Preparation of (±) -? - Fluoromethylglutamic acid

A solution of 6.56 g of α-methylglutamic acid hemihydrate in liquid hydrogen fluoride was photofluorized according to the general method described in the Journal of the American Chemical Society, 92,7494 (1970) and ibid, 98,5591 (1976). The starting material was therefore dissolved in 120 ml of liquid hydrogen fluoride, and then irradiated with a 2500 W ultraviolet light source while the solution is mixing, and cooling in a cooling bath in a dry ice-acetone while fluoroxi trifluoromethanesulfonate (CF ₃ OF) gas (namely 3, 0 ml (measured at -78 ° C in a liquid state) is passed through the solution for 80 minutes. After a further 80 minutes of irradiation, a further similar portion of fluoroxy trifluoromethane gas was passed through the solution under the same conditions. The reaction mixture was then allowed to stand overnight in the cooling bath and further fluorinated (by adding irradiated fluoride trifluoromethane equivalent to 3 ml over 5 hours under irradiation). Finally, cooling was removed to remove the solvent and the reaction mixture was purged with nitrogen and the residue was concentrated twice in vacuo with 2.5N aqueous hydrochloric acid. The residue thus obtained is dissolved in 40 ml of water and 10 ml of concentrated hydrochloric acid solution are added to 10 ml of this solution. The resulting mixture was refluxed for nearly 68 hours and then treated with DARCO G-60 filter material. The filtrate is evaporated to dryness in vacuo and the residue is refluxed for 30 hours with 30 M hydrochloric acid. After filtration with DARCO G-60, the solution is evaporated to dryness and the residue is dissolved in 10 ml of concentrated hydrochloric acid and heated in a sealed glass tube in a 130 to 135 ° C oil bath for 24 hours. The solution is then evaporated to dryness in vacuo and the residue is dissolved in water and subjected to chromatography on a column of cation exchange resin (360 mL of 200/400 AG 50-X-12). The column was eluted with 2.6 L of water, 1.5 L of 0.1 N aqueous hydrochloric acid and then 0.15 N aqueous hydrochloric acid. The absorbance of the 15 ml fractions of the eluate was monitored by UV spectrophotometer at 206 nm. Fractions containing the first absorption peak were pooled and evaporated to dryness in vacuo to give α-fluoro-methyl-glutamic acid hydrochloride. The free amino acid is liberated from this salt by dissolving the salt in isopropanol, and the resulting solution is filtered and propylene oxide is added. A solution of a-fluoromethylglutamic acid containing 0.7 mol of water of crystallization is crystallized from the solution. This compound is a time dependent inhibitor of the enzyme glutamic acid decarboxylase.

Analysis calculated (MW = 179.15): C, 38.30; H, 5.89; N, 7.45; F, 10.10 Found: C, 36.55; H, 6.14, N, 7.11, F, 9.64

The R, Sa-fluoromethyl meta-tyrosome can also be prepared as described in Example 1. NMR (60 MHz, D ₂ O, δ ppm): 2.65, 2.90, 3

3.25 (ABq, CH ₂ ); 4.03 4,20,4,32,4,80, 5.00, 5.08 and 5.25 (two ABq, _M-CH2), 6.65 and 7.15 (two m, aromatic)

Example 10

The following compounds may also be prepared as described in the previous examples:

S-α-fluoromethyl-tyrosine methyl ester, m.p. 106-

Mp 107 ° C

S-a-fluoromethyl-tyrosine methyl ester hydrochloride

Analysis results for C _U H _{1 S} NO ₃ C ₁ F (molecular weight = 263.70):

Found: C, 50.10; H, 5.73; N, 5.31; Cl, 13.45; F, 7.21;

Found: C, 50.28; H, 5.82; N, 5.24; Cl, 13.46.

F% = 7.28.

S-a-fluoromethyl-L-tyrosine ethyl ester

Nuclear Magnetic Resonance Spectrum (60 MHz, CDCl ₃ , δ ppm): 1.15.1.25 and 1.35 (CH ₃ , t); 2.55 2,75,2,90 and 3.10 _(CH2, ABq); 3.95 (NH ₂ , OH, 5H); 4.00, 4.12, 4.25, 4.45, 4.68, 4.82, 5.04 and 5.18 (CH ₂ F, two ABq) and 6,58,6,70,6 , 85 and 7.00 (aryl, ABq).

S-a-fluoromethyl-tyrosine ethyl ester hydrochloride

Analytical results based on the formula Ci ₂ Hi ₇ NO ₃ C1F (molecular weight = 277.71):

Found: C, 51.90; H, 6.16; N, 5.04; Cl, 12.77; F, 6.84;

Found: C, 51.70; H, 6.13; N, 4.93; Cl, 12.92.

F% = 6.87.

R, S-a-fluoromethyl-arginine:

NMR (2N DC1, δ ppm): 1.5-2.3 (4H, m, _{-CH2 CH2} -), 3.3 (2H, t, -CH ₂ NH-) and 4.9 (2H, 2dd, CH ₂ F, J _HF = 46 Hz)

Mass Spectrum (after silylation to the corresponding pentasilyl derivative) = 566 m / e (Molecular Weight: 206 + 5: 72 = 566). R, S-α-fluoromethyltryptophan:

UV spectrum: λmax = 278 nm (ε = 5.5 · 10 ³ )

Nuclear Magnetic Resonance Spectrum (300 MHz, D ₂ O + DC 1, δ ppm): 3.23, 3.35 (CH ₂ , ABq), 4.56,4,70,4,86, 5,00 (CH ₂ F). , 4d) symbols which may be assigned to the hydrogen atoms of the tryptophan moiety:

Claims (4)

Patent claims A process for the preparation of a racemic or optically active compound of formula I wherein: R is 3,4-dihydroxybenzyl, 4-hydroxybenzyl, 3-hydroxybenzyl, 3-aminopropyl, 2-carboxyethyl, imidazol-4-ylmethyl, indole. 3-ylmethyl or 3- (1-guanidyl) propyl, and R is hydrogen or C 1-4 alkyl - and their pharmaceutically acceptable acid addition salts, characterized in that (a) a racemic or optically active compound of formula II, wherein R is as defined herein, with sulfur tetrafluoride in liquid hydrogen fluoride at a temperature between 80 ° C and + 20 ° C, optionally in the presence of boron trifluoride or aluminum trichloride Fluoride dehydroxylation, or b) irradiating the racemic or optically active compound of formula VII, wherein R is as defined herein, in liquid hydrogen fluoride in the presence of fluoroxy trifluoromethane at -80 ° C to + 20 ° C, and in this case, a compound of formula I thus obtained, wherein R 1 is hydrogen, is known It is converted into a C 1-4 alkyl ester and / or converted into an acid addition salt and / or separated into optically active isomers. (Priority: May 30, 1978) 2. A process for the preparation of a racemic or optically active compound of formula I wherein: R is 3,4-dihydroxybenzyl, 4-hydroxybenzyl, 3-hydroxybenzyl, 3-aminopropyl, 2-carboxyethyl, imidazol-4-ylmethyl, indole. 3-ylmethyl or 3- (1-guanidyl) propyl, and R 5 is hydrogen or C 1 -C 4 alkyl, or a pharmaceutically acceptable acid addition salt thereof, characterized in that a racemic or optically active compound of formula II, wherein R is as defined above, in sulfur tetrafluoride in liquid hydrogen fluoride - fluoride dehydroxylation at 80 ° C to + 20 ° C, optionally in the presence of boron trifluoride or aluminum trichloride, and if desired, converting the resulting compound of formula I containing R 15 into hydrogen into a C 1-4 alkyl ester in a known manner; / or converted into an acid addition salt and / or separated into optically active isomers. (Priority: 06/01/1977) 3. A process according to claim 1 or 2, wherein the starting materials of the S configuration are used. (Priority: 06/01/1977) A process for the preparation of a pharmaceutical composition comprising the steps of a) or b) the compound of formula I prepared by process wherein: R and Rj are as defined in claim 1 and / or a pharmaceutically acceptable acid addition salt thereof in admixture with carriers and / or excipients known in the art of pharmaceutical manufacture to form a pharmaceutical composition in a known manner. (Priority: May 30, 1978) 5. A process for the preparation of a pharmaceutical composition comprising the compound of the formula I according to claim 2, wherein R and R 1 are as defined in claim 2, and / or a pharmaceutically acceptable acid addition salt thereof, in a pharmaceutically acceptable carrier. and / or mixed with excipients in a manner known per se to form a pharmaceutical composition. (Priority: 06/01/1977)