DE1073500B - Process for the production of peptides - Google Patents

Description

Process for the preparation of peptides Although all peptide syntheses based only on a single reaction, namely on the formation of an acid amide bond, there are a very large number of different methods. This fact shows that the previously known methods adhere to various disadvantages, so that the desire according to a generally applicable reaction proceeding in smooth reaction with good yield Synthesis is still unsatisfied.

It has now been found that the production of peptides, namely both oligo- and polypeptides in simple reaction and excellent Yield is achieved if you use aminocarboxylic acid hydrazides, their amino group expediently is protected in a manner known per se, is reacted with 1,3-diketo compounds and treated the obtained pyrazole derivative with aminocarboxylic acid esters. From the emerging The substituted pyrazole formed is then separated off from the reaction mixture, wherein the peptide can be isolated in a simple manner. By splitting off the amino group protective radical and / or splitting of the ester group one arrives at the corresponding peptide with free amino and carboxyl groups.

The reaction is explained below in terms of a formula using the example of aminoacetic acid hydrazide and acetylacetone and aminoacetic acid ester.

Here R denotes a radical protecting the amino group and R ' a hydrocarbon residue.

The amino acid hydrazides used as starting material can be used in in a manner known per se, for example from the corresponding aminocarboxylic acid esters be won. It is appropriate to use such compounds for the implementation in which the amino group is protected by a residue is. Appropriately to block the amino group, such radicals are introduced which can be used later if desired are easily split off. Examples include carbobenzoxy, toluenesulfonyl, the trityl and the trifluoroacetyl radical. However, other radicals can also be used, for example the carbethoxy radical, can be used to protect the amino group.

As 1,3 - diketo compounds there may be mentioned, for example, acetylacetone, Benzoylacetone, dihenzoxylmethane. It is especially beneficial to have a symmetrical one Use 1,3-diketover compounds having molecular structure. Particularly proven has acetylacetone as a reaction component, because that in the invention Reaction of this resulting 3,5-dimethyl-pyrazole with steam is readily volatile and as a result can be easily removed from the reaction mixture can.

The reaction of the aminocarboxylic acid hydrazides with the 1,3-diketo compounds can be carried out in the presence or absence of solvents.

Such organic solvents are suitable as solvents, which do not contain any basic groups. The implementation becomes advantageous at moderate carried out at elevated temperature. It is advisable to work between about 60 and 100 o /. In general, the implementation proceeds with a satisfactory speed, when the reaction mixture is heated on the water bath and the solvent thereby is kept simmering.

The yields of the resulting pyrazole derivative are in general over 80 to 90 ° / o. The pyrazoles are crystallized compounds that result from Alcohol or from water-containing alcohol are easily recrystallized, but with increasing molecular weight of the aminocarboxylic acid or peptide residue, the solubility decreases.

The obtained pyrazole derivative is then treated with an aminocarboxylic acid ester implemented. In this case, an aminolysis of the pyrazole derivative occurs, with the Aminocarboxylic acid residue bonded to nitrogen atom of the pyrazole ring as a substituent enters the amino group of the aminocarboxylic acid ester molecule.

At the same time, that of the opposite 1,3-diketo compound is formed corresponding free pyrazole, which can be easily removed from the reaction mixture can. As already mentioned, the resulting 3,5-dimethylpyrazole when using acetylacetone Easily volatile with water vapor and can thus be driven off.

The reaction of the acrylated pyrazole with the aminocarboxylic acid ester is also expediently increased by heating the component to moderately Temperatures up to about 1000 C, preferably to about 75 to 1000 C to undertake. Here, too, heating on a water bath has proven itself. Implementation of the component can be done without the use of solvents, but can of course solvents can also be used. However, the prerequisite is that the used Solvent is a weaker base than the aminocorbonic acid ester used. It is advantageous to use low molecular weight aliphatic alcohols as solvents use. The reaction mixture is first worked up by vacuum distillation, the excess amino acid ester and any solvent present removed. This is followed by steam distillation in which the pyrazole formed by the aminolysis is separated off. What remains is one with Waser immiscible oil, which according to the usual Chen methods brought to crystallization can be.

If the reaction described above is based on aminocarboxylic acids off, one first obtains a dipeptide whose reactive amino group is substituted and whose carboxyl group is esterified.

This dipeptide ester can be converted in a manner known per se converted with hydrazine into the hydrazide and again the reaction according to the invention be subjected. In this way it is possible to build higher peptides. Of course Both the same and different aminocarboxylic acid residues can form peptide molecules linked. The free peptides can be extracted from the resulting esters in a simple manner Way by cleavage of the ester and cleavage of the substituting the amino group Remnants can be obtained. The cleavage of the introduced to protect the amino group The remainder takes place in a manner known per se, for example by catalytic hydrogenation with the carbobenzoxy or toluenesulfonyl radical or by weakly alkaline hydrolysis at the trifluoroacetyl radical.

The method according to the present invention allows in excellent Yield to produce the corresponding pyrazole derivatives, which in turn again can be converted into the aminocarboxylic acid esters in very good yield. the The pyrazole residue is split off in the most gentle manner, and the resultant substituted pyrazole can easily be completely removed. The procedure permitted it, using also optically active aminocarboxylic acid components Build up peptides and is universally applicable.

The invention is illustrated below using a few examples: Example 1 a) 16.0 g of N- (p-toluenesulfonyl) glycine hydrazide are dissolved in 50 ml of ethanol and the solution with the addition of 7.0 g of acetylacetone for 3 hours on the water bath Reflux heated to boiling. On cooling, the 1- [N-p-toluenesulfonyl- (glycyl) j -3,5-dimethylpyrazole partially and can be filtered off. From this filtrate can be added by adding a little water and leaving the mixture to stand can be obtained in the freezer. The yield is 16 g = 80.4% of theory. the Compound can be recrystallized from aqueous ethanol. She owns one Melting point from 112 to 1130 C. b) 6.1 g of I- [N-p -Toluenesulfonyl- (glycyl) l-3,5-dimethylpyrazole are heated with 2.5 g of dl-alanine ethyl ester for 60 minutes on a boiling water bath. Bereixs after a short time a thick oil develops, from which after completion of the conversion the excess alanine ester is removed by vacuum distillation.

The oil is then subjected to steam distillation, the 3,5-dimethylpyrazole formed in the aminolysis being removed. It remains behind an oil immiscible with water. This is absorbed in ether, the ethereal solution dried, the ether distilled off and the remaining oily residue by trituration brought to crystallization with water.

5.3 g (= 80.7% of theory) of N- (p-toluenesulfonyl) -glycyl-dl-alanine ethyl ester are obtained of melting point 570 C. The compound is after recrystallization from aqueous Ethanol shows white needles. C) 8.7 g-: l! T- (p-toluenesulfonyl) -glycyl-dl-alanine ethyl ester are with the addition of 30 ml of abs. Ethanol with excess hydrazine hydrate Heated to boiling under reflux on a water bath for 60 minutes. In the cold --- best by standing in the refrigerator for several hours - the appropriate crystallizes Hydrazide. The yield is 6.8 g = 83% of theory. The connection can recrystallized from a little ethanol or from aqueous ethanol. She melts at 167 to 1680 C. d) 3.1 g of N- (p-toluenesulfonyl) -glycyl-dl-alanine hydrazide with 1.5 g of acetylacetone with the addition of 15 ml of abs. Ethanol for 3 hours on the water bath heated to boiling under reflux. The pvrazole derivative formed can be extracted from the reaction solution brought to crystallization by trituration with water and separated. Man receives 2.6 g (= 70.5 0 / o of theory) i- [N-p -Toluenesulfonyl- (glycyl-dl-alanyl) ] 3,5-dimethylpyrazole, which after recrystallization from hydrous alcohol or a mixture of ethyl acetate and petroleum ether melts at 143.5 to 144.50 C. e) 3.8 g of the pyrazole derivative obtained in the manner described above under d) are heated with 1.8 g of dl-valine ethyl ester on a water bath until has formed a clear solution. After about 2 to 3 hours, the excess will then be Valine ethyl ester is distilled off in vacuo and then the resulting 3,5-dimethylpyrazole removed.

The remaining oil, which cannot be mixed with water, turns into ethyl acetate added and by propelling after the addition of petroleum ether to crystallize brought. 2.4 g (= 56.10 / 0 of theory) of a white powder are obtained, which the N - p - toluenesulfonyl - glycyl - dl - alanyl - dl - valine ethyl ester, melting at 133.5 to 1350 C represents.

Example 2 a) 2.6 g of N - (p - toluenesulfonyl) - dl - alanine hydrazide, 1.2 g of acetylacetone and 10 ml of ethanol are refluxed on a water bath for 3 hours heated to boiling. When the reaction has ended, the pyrazole compound crystallizes out in the cold. It is advantageous to keep the reaction mixture in for several hours Icebox let stand. The precipitate is deposited. From the filtrate can by adding a further proportion of the reaction product obtained in crystalline form from a little water will. 1.9 g (= 600 /, of theory) 1- [N - p - toluenesulfonyl - (dl -alanyl) j -3,5-dimethylpyrazole with a melting point of 144.5 to 145.50 C. b) 3.2 g 1- [N-p-toluenesulfonyl- (dl-alanyl) j -3,5-dimethylpyrazole are mixed with 1.5 g of dl-alanine ethyl ester heated together for 30 minutes on a water bath. Already after a short time it forms a clear solution.

After the reaction, the excess dl-alanine ethyl ester is removed in vacuo distilled off and then the resulting 3,5-dimethylpyrazole by steam distillation removed.

The remaining oil, which cannot be mixed with water, is absorbed in ether, the ethereal solution evaporated to a small volume and the concentrated ethereal Solution poured into 150 ml of water. The last remains of aether will evaporate in the air calmly. The remaining water-immiscible oil solidifies after a while Time crystalline. It is necessary to do this by letting the mixture stand to speed up in the closet.

2.5 g (= 75 ovo of theory) of N-p-toluenesulfonyl-dl-alanyl-dl-alanine ethyl ester are obtained. The compound can be recrystallized from a mixture of ethyl acetate and petroleum ether.

Claims (1)

PATENT CLAIM: Process for the production of peptides, characterized in that that one amino acid hydrazides whose amino group is expediently known per se Wise protected, reacted with 1,3-diketo compounds, the resulting pyrazole derivative treated with alnino acid esters, the substituted pyrazole formed by aminolysis separates and optionally the radical protecting the amino groups and / or the ester group splits off.