CS212988B1 - Process for the preparation of 4-amino-N, N-methylpteroylglutamic acid - Google Patents

Abstract

The invention relates to a method for the production of 4-amino-N10-methylpteroylglutamic acid, also called methotrexate, which is used in human medicine for the treatment of cancer. Methotrexate has been prepared in several different ways, which have been relatively disadvantageous. The method according to the invention consists in condensing 2,4-diamino-6-chloromethylpteridine hydrochloride with N-p-(N-methylamino)-benzoyl-glutamate ethyl in an aqueous medium at a given temperature, pH and for a certain time. 2,4-diamino-6-chloromethylpteridine hydrochloride is added to the reaction mixture in an organic solvent, such as formic acid. The advantage of this method for the preparation of methotrexate is the direct use of N-p-(N-methylamino)-benzoyl-glutamic acid diethyl ester. The purity of the prepared methotrexate is higher than 95%. The reaction can be represented as follows:

Description

(54)

A process for the preparation of 4-amino-N? -Methylpteroylglutamic acid

The invention relates to a process for the production of 4-amino-N ¹⁰ -methylpteroylglutamic acid, also called methotrexate, which is used in human medicine for the treatment of cancer. To date, methotrexate has been prepared in several different ways, but these have been relatively disadvantageous. The process according to the invention consists in condensing

2,4-diamino-6-chloromethylpteridine hydrochloride with N- p- (N-methylamino) -benzoyl-glutamate ethyl acetate in aqueous medium at given temperature, pH and for some time. 2,4-Diamino-6-chloromethylpteridine hydrochloride is added to the reaction mixture in an organic solvent such as formic acid. The advantage of this process for the preparation of methotrexate is the direct utilization of diethyl N- [beta] - (N-methylamino) -benzoyl-glutamic acid diethyl ester. The purity of the methotrexate prepared is greater than 95%.

The reaction can be illustrated as follows:

CO-NH-CH-COOH

I ch ₂ -ch ₂ -cooh

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The present invention relates to a process for the preparation of 4-amino-N acid

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-methylpteroylglutamic formula I ch ₂

CO-NH-CH-COOOH

AND

OH ₂ -CH ₂ -COOH (I)

This compound, called the same methotrexate, is used in human medicine for the treatment of malignancies.

To date, methotrexate is prepared by condensation of 2,4-diamino-6-bromomethylpteridine hydrobromide with N- (p- (N-methylamines) -benzoyl) -glutanate (Piper JR, ionomers JA: J.Org.CHem. 47. 208 (1977)). A disadvantage of this method is the difficult availability of 2,4-diamino-6-bromomethylpteridine hydrobromide. This material is prepared from 2,4-diamino-6-hydroxymethylpteridine via its hydrobroitide formed by reaction with concentrated hydrobromic acid in ethanol, followed by reaction with bromine, triphenylphosphine and dimethylacetamide. The yield of 2,4-diamino-6-bromomethylpteridine hydrobromide from these two reaction steps is only 20% based on the starting 2,4-diamino-6-hydroxymethylpteridine. After completion of the reaction, it is necessary to remove the dimethylacetamide from the reaction mixture by distillation at 45 ° C, which requires a relatively high vacuum (less than 100 Pa). The condensation of 2,4-diamino-6-bromomethylpteridine hydrobromide with N- (p- (N-methylamino) -benzoyl) -glutamine ethyl is carried out in dimethylacetamide, which is a difficult to obtain raw material. This method is preparatively interesting, but not suitable for larger technology.

Another known method of preparing methotrexate is by reacting 2,4-diamino-6-chloromethylpteridine-βH- (p- (N-methylamino) benzyl) -glutamic acid (Brit. Pat. 1,414,752).

A disadvantage of this procedure is the use of N- (p- (N-methylamino) -benzoyl) -glutamic acid, since this compound is prepared from the corresponding diethyl ester. The purity of the methotrexate prepared by this procedure is only 60%. Further purification of methotrexate by one of the chromatographic methods is necessary, which means a complication for the technology, especially from the hock disc of time and raw material intensity.

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The above disadvantages are overcome by a process for preparing 4-amino-N-methylpteroylglutamic acid of Formula I which comprises condensing 2,4-diamino-6-chloromethylptarldine hydrochloride (Formula II) and N- [p- (N-methylamino)]. Ethylblutoyl} -benzoyl} -glutaman (Formula III) nh ₂

ch ₂ -ci. HCl (II)

NH

CH,

-CO-NH-CH-COOH

AND

CH, (III) ¹²

CH ₂ -COOOC ₂ H ₅ in the presence of water at 10 to 80 ° C for 5 to 100 hours, at pH 2 to 14,2,4-diamino-6-q-methylpteridine hydrochloride is added to the reaction mixture in an organic solvent, for example in an acid ant. The advantage of this new process for the preparation of methotrexate is that it directly uses diethyl N- (p * (N-methylamino) -benzoyl) -glutamic acid in combination with 2,4-diamino-6-chloromethylpteridine hydrochloride, a relatively readily available reaction

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2,4-diamino-5-hydroxymethylpteridine β thionyl chloride in 90% yield. the purity of the methotrexate prepared is greater than 95% (HPLC). The methorexate thus prepared does not require further purification and is suitable for use in human medicine after formulation.

Example

To 125 ml of 0.2 M NaOH was added 3.5 g of ethyl N- (p- (N-methylamino) -benzoyl-3-glutamate), and after stirring at 20 ° C for 2 hours, a solution of 30 g of sodium acetate in 150 ml of water was added. The pH of the reaction mixture was adjusted to 4.2 with 1 N HCl and a solution of 2 g 2,4-diamino-6-chloromethylpteridine hydrochloride in 15 ml of 85% formic acid was added over 1 hour with stirring. The mixture was heated to 45-50 ° C and stirred at this temperature for 20 hours.The precipitated orange solid was filtered off, dissolved in water at pH about 10.5-11 (pH adjusted with sodium carbonate) and the solution was briefly heated to 60 ° C. The filtrate was cooled to 2-4 ° C and adjusted to pH 7 with 1 n HCl to pH 7. The filtrate was acidified with 1 N HG1 to pH 2-4. Dried under vacuum to an o at a temperature of up to 50 [deg.] C. Yield 1.5 g of a purity of at least 95% (HPLC).

Claims (1)

SUBJECT OF THE INVENTION A process for the preparation of 4-amino-N-methylpteroylglutamic acid by reacting 2,4-diamino-6-chloromethylpteridine hydrochloride with amino) -benzoyl) -glutamate (Formula III) of Formula I characterized by (Formula II) with N- [beta] - ( N-methyl in the presence of water at 10 to 60 ° C for 5 to 100 hours at pH 2 to 14. 2. The process of claim 1 wherein 2,4-diamino-6-chloromethylpteridine hydrochloride is added to the reaction mixture in an organic solvent, such as formic acid.