DD208609A1 - METHOD FOR PRODUCING POLYAMINOSAURES - Google Patents

Abstract

It is the object of the invention to provide biologically active polyamine acids for use as active ingredients. According to the invention, a mixture of an amino acid ester of the general formula I and an aldehyde of the general formula II is catalytically hydrogenated, the protecting group is removed by hydrolysis from the resulting compound of the general formula III, the compound of general formula IV thus obtained together with an aldehyde of the general formula II reacted in the presence of a base by catalytic hydrogenation to the compound of general formula V and this to the corresponding compound d. hydrolyzed general formula VI. The compounds prepared are for d. Land-, Garten- u. Forstwirtsch. as well as d. Medicine of interest.

Description

Process for the preparation of polyamino acids

The invention relates to a process for the preparation of polyamino acids of the general formula VI. These are nicotianamine and analogues.

Field of application of the invention

The compounds produced are biologically active. They act as metal carriers and are therefore of interest for agriculture, horticulture and forestry as well as for medicine.

Characteristic of the known technical solutions

It is known that the biologically active nicotianamine (formula VIa / 1) can be prepared by boiling S-azetidine-2-carboxylic acid with sodium hydroxide solution and subsequent expensive purification in 4% yield (I. KRISTENSEN and PO LARSEN, Phytochemistry 1j >> 2791 (1974)). A further synthesis (S., FUSHIY et al., Heterocycles Ij, 819 (1981)) starts from OS) -J-benzyloxycarbonylamino-ethoxycarbonyl-propionaldehyde, which is treated with S-azetidine-2-carboxylic acid methyl ester in the presence of sodium cyanoborohydride (2S: 3 ^{l of} S) -N- (3-amino-3-carboxypropyl) -azetidine-2-carboxylic acid. Reaction of this compound with (3S) -3-benzyloxycarbonylamino-5-tert-butoxycarbonylpropionaldehyde under analogous conditions gives after cleavage of the protective groups nicotianamine. However, this method is based on aldehydes, which are accessible only through a complicated, multi-step synthesis.

Only a few representatives with nicotianamine analogous structure are known (H. RIPPERGER and K. SCHREIBER, Heterocycles 12 »447

2410 89 p

(1982)). So became ζ. B. 2'-Deoxymugineinsäure synthesized, which differs from nicotianamine by replacing the primary amino group against a hydroxy group. Avenin A, which is also accessible by synthesis, has a homoserine residue linked to the nitrogen atom instead of the azetidine ring in nicotianamine. «

Nicotianamine analogous polyamino acids of the general formula YI are hitherto unknown.

Object of the invention

It is the object of the invention to provide biologically active polyamino acids for agricultural and medical practice as active ingredients available, which when applied in agriculture, the required application rate to achieve the effect of phytohormones in the same order of magnitude should be.

Explanation of the nature of the invention

The invention has for its object to develop a simple process for the preparation of polyamino acids of general formula VI.

According to the invention, a mixture of an amino acid ester of the general formula I, preferably the ethyl ester, and an aldehyde of the general formula II is catalytically hydrogenated. From the resulting compound of general formula III, the protecting groups are removed by alkaline or acid hydrolysis. The compound of general formula IV thus obtained, together with an aldehyde of general formula II in the presence of a base, in general a tertiary nitrogen base, for example triethylamine, again a catalytic! Subjected to hydrogenation. In this case, the corresponding compound 'of the general formula V is prepared. Alkaline hydrolysis finally gives the compound of general formula VI.

1 2

In the formulas I to VI, R and R, independently of one another, denote hydrogen or alkyl (O 1 -C 4) or

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methylene (C ₂ -C ₁ -), R is lower alkyl, preferably ethyl, R is alkyl (C ₂ -C ₄ ), η is n 1 or n ₂ , where n 1 and n p are independently 1, 2, 3 or 4, preferably 1 or 2, and X is a protecting group which is not split off in the linking of aldehyde and amine components by catalytic hydrogenation, in particular for the trifluoroacetyl radical.

The starting materials are synthesized by known methods (K.-H. DEIMER et al., In Methods of Organic Chemistry (Houben-Weyl), 4th Edition, Volume XV / 1, Georg Thieme-Verlag, Stuttgart, 1974, S. 315, and F. WEYGAND and H. FRITZ, Chem. Ber. 28, 72 (1965)).

The aldehyde of the general formula II used as reactant in both hydrogenations is the same in both reaction stages (n ^ i = n ₂ ) or a different aldehyde is selected for each stage, the two aldehydes differing only in the number of methylene groups ( n ^ φ η ₂ ).

The reaction conditions in the reaction of the amino acid ester of general formula I to the compound of general formula III and in the reaction of the compounds of general formula IV to those of general formula V are the same in terms of temperature, pressure and catalyst. It works in an organic solvent, preferably at room temperature and atmospheric pressure, while the catalyst is in particular palladium on activated carbon (containing 10 % palladium) is used. As solvents are alcohols, for. As methanol or ethanol, or solvent mixtures suitable.

The compounds of general formulas III and V prepared are hydrolysed as crude product while the compounds of general formulas IV and VI are purified by known methods, generally by adsorption on a cation exchanger, subsequent elution with dilute aqueous ammonia solution and subsequent recrystallization of the crude products ethanol / water.

  - 4 - & ή Ι U

Among the compounds of general formulas III, IV, V and

Λ P VI is only one known (nicotianamine: VI, R + R = - (CHp) p-, rtj = up = 1), all others are new. The method according to the invention enables a targeted and systematic modification of the nicotianamine molecule. Compared to the known synthesis of nicotianamine, the novel process has the following advantages:

- The aldehyde of the general formula II used is accessible in substantially less synthetic steps.

- By using a different protection group technology, a linkage of aldehyde and amine components by catalytic hydrogenation is possible.

- The purification of the reaction products is carried out in a simple manner.

Also for the production of radioactively labeled polyamino acid

14

ren, for example C-labeled compounds, the inventive method is suitable.

Besides nicotianamine, structurally analogous polyamino acids of the general formula VI are also distinguished by biological activity. In the foreground are chelating properties for metals, eg. As iron, copper, zinc, manganese. As a result of these properties, nicotianamine and nicotianamine-analogous polyamino acids act as carriers in higher plants. The novel process enables the preparation of such nicotianamine analogs with altered biological activity which are required for the study of biosynthesis, metabolism, transport, distribution, mode of action and structure-activity analysis of the compound type as a basis for the development of new drugs. The invention provides novel metal oarriers which are suitable for e.g. For example, to eliminate specific ironmange diseases (iron chlorosis) in agricultural, horticultural or forestry crops. Among the compounds which can be prepared according to the invention are those in which the required application rate for achieving the desired effect is of the same order of magnitude as the effective amount in the case of phytohormones. The

Polyamino acids of the general formula VI are also of interest to medicine, e.g. As for the treatment of hemosiderosis or idiopathic hemochromatosis.

The following exemplary embodiments illustrate the invention, wherein the specific conditions specified therein do not limit the invention.

embodiments

A selection of compounds which are prepared by the process according to the invention contains the following equation.

241 089

For melschema to the examples

H CO ₂ C ₂ H ₅

H CO ₂ C ₂ H ₅

R ¹ -C _x H CO ₂ C ₂ H ₅ RC H CO ₂ C ₂ H ₅

|H ♦ OHC- (CH ₂ J _n ^ C-NHCOCF ₃ ^ 2_N- (CH ₂ J _{n + 1} -C-NHCOCF ₃ ^R R2

la

! a

H CO ₂ H

H CO ₂ H

^Rl -C \ -, /

^ N- (CH ₂ ) _{ni + r} C-NH ₂

OHVor H ⁺

IVa

HCO ₂ H

H ^ CO ₂ C ₂ H _{5 h} RC _C H CO ₂ H η CO ₂ C ₂ H ₅

IVa ♦ OHC- (CH ₂ ) -t-NHCOCF ₃ -2+ ^ N- (CH ₂ ) _n , -C-NH- (CH ₂ ) _n ., - C-NHC OCE

R2

Va

HCO ₂ H

R2

H CO ₂ H

Via

H CO ₂ H

la, Ilia, IVa, Va, Via R ¹ R ^{2 n} 1 n ₂ 1 - (CH ₂ J ₂ - 1 1 2 - (CH ₂ J ₃ - 1 1 3 - (CH ₂₎ - 1 1 k (CH ₂ J ₂ - 2 1 5 - (CH ₂ J ₂ - 1 2 6 (CH ₂ J ₂ - 2 2 7 H H 1 1 8th C ₂ H ₅ H 1 1

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The following is an example of the preparation of the compounds 2 (see formula scheme) of the general formulas IHa, IVa, Va and VIa.

- Synthesis of (2S: 3'S: 3 ''S) -N - / "3- (3-Ami ⁿ o-3-carboxypropylamino) -3-carboxypropyl_7-proline (VIa / 2)

573 mg (4 mmol) of S-proline ethyl ester (Ia / 2) with 965 mg (4 mmol) of (3S) -3-ethoxycarbonyl-3-trifluoracetylaminopropionaldehyd (Ha, n ^, = 1) in 30 ml of dry ethanol at atmospheric pressure and Room temperature for one hour in the presence of

1 g Pd / C (10% Pd) catalytically hydrogenated. The reaction solution is filtered off from the catalyst and i. Vak. concentrated. To remove the protecting groups can be hydrolyzed alkaline or acid.

Alkaline hydrolysis: The residue is dissolved in 50 ml of 1% strength aqueous ethanolic KOH and the solution is added after 20 hours to an ion exchange column (Dowex 50 WX 4, 100 mesh, loading: 1)

2 N ΝΗ -, - solution eluted. Concentration of the solution i. Vak. provides 767 mg of crude product. The purification is carried out by recrystallization from ethanol / water = 9: 1 or by column chromatography aii silica gel (particle size 63-200 pm) . It is first washed with ethanol and then eluted with ethanol / water = 1: 1. To remove silica gel, fractions containing compound IVa / 2 are added to a cation exchange column (see above), washed with water and eluted with 2N solution. Concentration of the solution gives 482 mg (51% of theory) of a white, amorphous product. The compound is DC-pure and can be further processed without further purification.

Acid hydrolysis: The reaction residue is dissolved in 10 ml of ethanol and heated with 2 x 20 ml of 18% hydrochloric acid (2nd addition after 15 min.) On a water bath for 30 min. The reaction mixture is evaporated, taken up in a little water, added to a cation exchange column (see above), washed with water and eluted with 2N NH 4 solution. Then it is re-evaporated and distilled several times ethanol. To the

083 5

Residual is added ethanol and filtered. It leaves 519 mg of white, DC-pure product. Concentration of the filtrate and repetition of the hydrolysis procedure yield a further 61 mg of compound IVa / 2 (total yield: 580 mg = 62% of theory). The compound is present as a monohydrate.

Mp 5> 190 ⁰ G Zers. (recrystallized from ethanol / water = 9: 1) ^R F: '0.34 (TLC on silufole with n-propanol / water = 6: 7,

Proof with ninhydrin) j & 5 °

= -49.5 ° (ο = 1.0, H ₂ O).

117 mg (0.5 mmol) of IVa / 2 are mixed with 121 mg (0.5 mmol) of aldehyde (Hb, np = 1) and 0.5 ml of triethylamine in 30 ml of methanol in the presence of 100 mg Pd / G (10%). Pd) at normal pressure and room temperature for 5 hours. It is filtered off from the catalyst and i. Vak. concentrated. The cleavage of the protecting groups is carried out by alkaline hydrolysis. For this, the residue with 20 ml of 1 N aq. KOH treated. After 30 min, the reaction solution is added to a cation exchange column (Dowex 50 WX 4, 100-200 mesh), washed with water and eluted with 2N NH 4 solution. Concentration of the solution gives 133 mg of crude product, which is recrystallized from ethanol / water. Compound VIa / 2 is present as trihydrate.

Yield: 112 mg (60 % of theory )

M .:> 220 ⁰ C Zers.

IL ₁ : 0.28 (silufole, n-propanol / water = 6: 7, ninhydrin) ^ ₌ -26.7 ° (c = 0.44, H ₂ O).

Claims (6)

- 9 - 2 4 1 ü b 9 6 Invention claim t 1. A process for the preparation of polyamino acids, characterized in that a mixture of an amino acid ester of the general formula I and an aldehyde of the general formula II is catalytically hydrogenated, are removed from the resulting compound of general formula III, the protective groups by alkaline or acid hydrolysis, the so obtained compound of general formula IV is reacted together with an aldehyde of general formula II in the presence of a base by catalytic hydrogenation to the compound of general formula V and this is hydrolyzed alkaline to the corresponding compound of general formula VI, 1 2 where in the formulas I to VI, R and R independently of one another are hydrogen or alkyl (C 1 -C 4) or together for poly (ethylene) C 2 -C 4 -alkyl, R ^{4 is} lower alkyl, R ^{4 is} alkyl (C 1 -C ⁴ ) and η stands for n ^ or n ₂ , where n ^, and n _? independently of one another are 1, 2, 5 or 4, and X symbolizes a protecting group which is not split off in the linking of aldehyde and amino components by catalytic hydrogenation. 2. The method according to item 1, characterized in that X symbolizes a Trifluoracetylrest. 3. The method according to item 1 and 2, characterized in that the hydrogenations are carried out at room temperature under atmospheric pressure in an organic solvent or a solvent mixture and wxrd used as the catalyst palladium on activated carbon. 4. The method according to item J, characterized in that alcohols are used as the solvent. 41 089 5. The method according to any one of items 1 to 4, characterized in that in the reaction of the compounds of general formula IV to the compounds of general formula V as the base, a tertiary nitrogen base is used. 6. Method according to item 1 to 5> characterized in that n ^ | and n _? independently represent 1 or 2 For this 1 page formulas