WO1986000073A1

WO1986000073A1 - Process for preparing adriamycine and halide salts thereof

Info

Publication number: WO1986000073A1
Application number: PCT/HU1984/000037
Authority: WO
Inventors: János BÁLINT; Szabolcs BORBÉLY; Zsuzsanna Emri; József FAZEKAS; György TÓTH
Original assignee: BIOGAL Gyógyszergyár
Priority date: 1984-06-14
Filing date: 1984-06-14
Publication date: 1986-01-03
Also published as: JPS61502956A; FI860683A; FI860683A0; DK59486D0; DK59486A; DK157082C; EP0183691A1; DK157082B

Abstract

The halide salts of adriamycine are useful antitumor antibiotics. Adriamycine and halide salts thereof are prepared with high yields from daunomycine or halide salts thereof by reacting daunomycine or a halide salt thereof with bromine in an anhydrous organic solvent system in the presence of a solvent suitable for ketal formation, transforming the formed 14-bromo derivative into a 14-hydroxy derivative in a manner known per se, optionally acidifying the solution with a haloid acid and recovering the product, optionally after purification.

Description

PROCESS FOR PREPARING ADRIAMYCINE AND HALIDE SALTS

THEREOF

Background of the invention

This invention relates to a new process for preparing adriamycine and halide salts thereof.

As it is well known from the art adriamycine is an antitumor antibiotics which is used in the form of a halide for the treatment of tumouroua diseases.

Adriamycine can be produced directly by fermentation (Belgian Patent Specification Ho. 713,773) or by semisynthetic route from daunomycine (German Patent Specification No. 1,917,874 and US Patent Specification No. 4,012,448).

The semi-synthetic processes starting from daunomycine and including the preparation of daunomycinone and 7-deoxydaunomycinone as intermediates are very complicated as not only the starting material has to be transformed in the course of the procedure, but the sugar component of adriamycine, the daunozamine has also to be bonded to the molecule.

Adriamycine can be prepared by a more simple way from daunomycine through the 14-halo derivative of the latter, without changing the structure of the sugar moiety of the molecule (German patent specification No.

1,917,374).

According to this process the bromination can directly be carried out by using a solution of bromine in chloroform, while in the course of iodination the amino group of the daunozamine is protected by transforming the latter into an acyl derivative or a Schiff base, thereafter the protecting group is removed and the adriamycine thus obtained is purified by column chromatography. The simpliest way for preparing adriamycine from daunomycine by semi-synthetic route appears to be the direct bromination of daunomycine. However, when reproducing this process, we found that the daunozamine and the side-chain containing 14 carbon atoms can easily be splitted off, thus 14-bromodaunomycinone and other decomposition products without side-chain are formed. Thus, the bromination reaction results in a rather low, i.e. 58-59 %, yield. In view of the fact that the molecule is sensitive to acids and bases and susceptible to oxidation, in the course of the replacement of the bromine atom of 14-bromodaunomycine by a hydroxyl group and when the purification of the products is effected further losses occur, thus the yield based on the starting daunomycine is only about 6 to 13 %.

The present invention is aimed at developing a semi-synthetic process starting from daunomycine which enables to obtain adriamycine by a more simple and more economic way.

Summary of the invention

The process of the invention is carried out by reacting daunomycine or a halide salt thereof in an anhydrous organic solvent system in the presence of a solvent suitable for ketal formation, preferably in the presence of an alkyl ortoalkanecarboxylate or alkyl alkanoylate containing 1 to 6 carbon atoms in the alkyl moieties, with bromine, suitably at a temperature of 0 to 20 °C, preferably at 8 °C for 3 to 30 hours, preferably for 5 hours, thereafter transforming the formed 14-bromo derivative to the 14- hydroxy derivative in a manner known per se, optionally acidifying the solution with a haloid acid and recovering the product, optionally after purification.

Detailed description of the invention

Surprisingly we found that if the bromination is carried out in the presence of a solvent suitable for ketal formation, e.g. in the presence of triethyl orthoformate, the molecule obtained is much more stable, deacetylation reaction does not occur, the glycosidic bond cleavage is fairly less, therefore the 14-bromodaunomycine derivative can be prepared in a substantially higher yield.

According to our experiments e.g. the triethyl orthoformate reacts with the enolic form of the 13- keto group of the daunomycine molecule formed due to the bromine being present, thus a ketal is produced which stabilizes the molecule, prohibites the side-reactions and the alkyl group cleavage.

The solvent suitable for ketal formation, e.g. the triethyl orthoformate, can preferably be used in a molar amount of 1 : 3-4, calculated for daunomycine or the hydrochloride salt thereof. Thus the 11-bromodaunomycine derivative can be achieved in higher yields. By using e.g. triethyl orthoacetate, methyl formate or ethyl acetate, similar good yields can also be achieved, According to the process of the invention the 14- bromodaunomycine derivative need not to be recovered as the acetonic solution of 14-bromodaunomycine treated with hydrogen bromide can be directly used in a process where the bromo atom is replaced by a hrdroxyl group. This procedure can be carried out by a ranner well known in the art.

According to our experiments this process can more preferably be carried out through the 14-formyloxy derivative than by the direct conversion of the bromo atom to hydroxyl group by treating with sodium hydroxyde. The hydrolysis of the 14-formyloxy derivative at pH 7.6 to 8.0 assures much more favourable conditions for the adriamycine being less resistant against alkaline agents than acids, than the basic treatment at pH 10.3.

Before the alkaline hydrolysis of 4-formyloxydaunomycine the reaction mixture is preferably extracted with chloroform at pH 3.5 to 4.0 in order to remove the aglycone-type decomposition products. The pH of 7.6 to 8.0 required to the hydrolysis is preferably adjusted with a 5 % by weight solution of sodium bicarbonate, the adriamycine base formed is recovered from the reaction mixture by repeated extraction with chloroform. The extracts are concentrated, treated with a solution of hydrochloric acid in methanol in order to form adriamycine hydrochloride which is then precipitated from the solution with ether.

Adriamycine is used in the form of a halide salt for the preparation of medicaments, optionally after purification. The purification is carried out in a manner known per se.

The present invention is illustrated by the aid of the following non-limiting examples.

Example 1

1.4 g. (2.43 millimoles) of daunomycine hydrochloride are dissolved in a mixture of 20 ml. of anhydrous methyl alcohol, 56 ml. of anhydrous dioxane and 1.4 ml. (3.47 millimoles) of anhydrous triethyl orthoformate. To the solution thus obtained 0.5 g. (3.16 millimoles) of bromine dissolved in 5.4 ml. of anhydrous chloroform are added, the flask is closed and kept at 3 °C for 5 hours.

The reaction mixture is poured into a mixture of 230 ml. of diethyl ether and 120 ml. of petrol ether, the product precipitated is filtered off, washed with 3 x 30 ml. of diethyl ether in order to remove impurities. Then it is dissolved in a mixture of 40 ml. of acetone and 40 ml. of 0.25 N aqueous hydrogen bromide and kept at 25 °G for 17 hours. Thereafter a solution of 2.0 g. (29.4 millimoles) of sodium formate in 20 ml. of deionized water is added to the solution and stirred for 43 hours at 25 °C.

The pH of the reaction mixture is adjusted to 3.7 by adding 1 N hydrochloric acid solution and extracted with 50 ml. of chloroform five times. Then the pH of the aqueous phase is adjusted to 7.6 by adding a. 5 % solution of sodium bicarbonate and the adriamycine base is extracted from the mixture. The extraction is continued until the chloroformic extract is coloured.

The chloroformic extracts are washed with 5 To of deionized water, calculated for the volume of the extracts, and dried over anhydrous sodium sulphate. After the drying agent is filtered off, the solution is concentrated to a volume of 50 ml. The free base is transformed to its hydrochloric salt by treating with a calculated amount of anhydrous hydrochloric acid solution in methanol and the salt is precipitated with 500 ml. of diethyl ether. The product precipitated is filtered, washed four times with 30 ml. of diethyl ether and dried in vacuo at room temperature. Yield: 0.61 g, (42.4 % ) of adriamycine hydrochloride. The analytical data of the product are listed below.

^C27^H29^NO11^{.HCl (Mo lar weight: 530.0)} Elsmentar analysis:

Calculated: C % = 55.9, H % = 5.21, N% = 2.42,

Cl % = 6.11

Found: C % = 55.52, H% = 5.10, N % = 2.04, Cl % = 6.24 Melting point: 202 - 206 °C (with decomposition) Thin-layer-chromatography: Adsorbent: Kieselgel 60 (Merck 5724) impregnated with a 1 % solution of oxalic acid Eluent: the upper layer of a 4:1:5 mixture of n-butanol/- acetic acid/water Development: 10 cm R_f value: 0.33

Infrared spectra: (Perkin-Elmer 397 type apparatus, -¹

NMR:

( Bruker WP 200 SY impulse FT apparatus ; ¹H-NMR, DMSO-d6, room temperature , delta ppm, 250 MHz )

C

x: changeable assignations

Example 2

1.4 g. (2.48 millimoles) of daunomycine hydrochloride are dissolved in a mixture of 40 ml. of anhydrous methyl alcohol and 0.55 ml. (8.7 mmoles) of anhydrous methyl formate. To the solution thus obtained 0.5 g. (3.16 mmoles) of bromine in 5.4 ml. of anhydrous chloroform are added, the flask is closed and kept at 10 °C for 4.5 hours. The reaction mixture is poured into a mixture of

280 ml, of diethyl ether and 120 ml. of petrolether, the product precipitated is filtered off, the impurities are removed by washing with 3 x 30 ml, of diethyl ether. The product is dissolved in a mixture of 40 ml. of acetone and 40 ml. of 0.25 N aqueous hydrogen bromide and kept at a temperature of 25 °C for 17 hours. Then a solution of 2.0 g. (29.4 mmoles) of sodium formate in 20 ml. of deionized water is added to the reaction mixture and the solution is stirred for 48 hours at 25 °C.

The reaction mixture thus obtained is worked up according to Example 1.

Yield: 0.55 g. (38,6 % ) The identifying data of the end product are the same as given in Example 1, Example 3

0,70 g. (1,24 mmoles) of daunomycine hydrochloride are dissolved in a mixture of 10 ml, of anhydrous methyl alcohol, 30 ml, of anhydrous dioxane and 0,42 ml, (4.30 mmoles) of ethyl acetate. To the solution thus obtained 0,25 g. (l.58 mmoles) of bromine in 2.7 ml. of anhydrous chloroform are added, the flask is closed and kept at 6°C for 6 hours. The reaction mixture is poured into a mixture of 140 ml. of diethyl ether and 60 ml. of petrol ether, the product precipitated is filtered off and the impurities are removed by washing with 3 x 15 ml. of diethyl ether. The product is dissolved in a mixture of 20 ml, of acetone and 20 ml, of 0,25 N aqueous hydrogen bromide and kept at a temperature of 25 °C for 17 hours. Thereafter a solution of 1,0 g, (14,7 mmoles) of sodium formate in 10 ml, of deionized water is added to the reaction mixture and the latter is stirred at 25 °C for 48 hours.

The pH of the reaction mixture is adjusted to 3.7 by adding 1 N hydrochloric solution and the mixture is extracted with chloroform five times. Then the pH of the aqueous layer is adjusted to 7.6 by adding a 5 % solution of sodium bicarbonate and the adriamycine base is recovered by extraction. The extraction is continued until the chloroformic extract becomes uncoloured. The chloroformic extracts are washed with 5 To of deionized water, calculated for the volume of the extracts, then dried over anhydrous sodium sulphate. After filtering off the drying agent, the solution is concentrated in vacuo to a volume of 25 ml. The free base is transformed into its hydrochloric salt by treating with a calculated amount of

0.6 N anhydrous methanolic hydrochloric solution, thereafter the salt is precipitated by 250 ml. of diethyl ether. The product precipitated is filtered off, washed with 15 ml, of diethyl ether four times and dried in vacuo at room temperature.

Yield: 0.29 g. (40.3 %)

The identifying data are the same as indicated in Example 1. Example 4 0.70 g. (1.24 mmoles) daunomycine hydrochloride are dissolved in a mixture of 10 ml. of anhydrous methyl alcohol, 30 ml. of dioxane and 0.8 ml. (4.35 mmoles) of triethyl orthoacetate. To the mixture thus obtained 0.25 g. (1.58 mmoles) of bromine in 2.7 ml, of anhydrous chloroform are added, the flask is closed and kept at 6 °C for 6 hours.

The reaction mixture is poured into a mixture of 140 ml. of diethyl ether and 60 ml. of petrol ether, the product precipitated is filtered off, the impurities are removed by washing with 3 x 15 ml. of diethyl ether. The product is dissolved in a mixture of 20 ml. of acetone and 20 ml, of 0.25 N aqueous hydrogen bromide and kept at 25 °G for 17 hours. Then a solution of 1.0 g. (l4.7 mmoles) of sodium formate in 10 ml. of deionized water is added to the reaction mixture and the latter stirred at a temperature of 25 °C for 48 hours.

The reaction mixture thus obtained is worked up according to Example 3.

Yield: 0.30 g. (41.7 % )

The identifying data of the end product are the same as indicated in Example 1.

Claims

What we claim is:

1. Process for the preparation of adriamycine and the halide salts thereof from daunomycine or the halide salts thereof which comprises reacting daunomycine or a halide salt thereof with bromine in an anhydrous organic solvent system in the presence of a solvent suitable for ketal formation, then transforming the formed 14-bromo derivative into a 14-hydroxy derivative in a manner known per se, optionally acidifying the solution with a haloid acid and recovering the product, optionally after purification.

2. The process of claim 1 wherein the bromination is carried out at 0 to 20 °C, preferably at 8 °C, for 3 to 30 hours, preferably for 5 hours.

3. The process of claim 1 or 2 wherein an alkyl orthoalkanecarboxylate or alkyl alkanoylate containing 1 to 6 carbon atoms in the alkyl moieties is used as solvent suitable for ketal formation.

4. The process of claim 3 wherein triethyl orthoformate is used as alkyl orthoalkanecarboxilate.

5. The process of claim 3 wherein ethyl acetate is used as alkyl alkanoylate.

6. The process of any of the preceeding claims wherein a mixture of methanol and dioxane of 1 : 2-5 volume rate is used as anhydrous organic solvent system.

7. The process of any of the preceeding claims wherein the transformation of the 14-bromo derivative to the 14-hydroxy derivative is carried out by precipitating the 14-bromo derivative in an organic solvent system, then reacting with hydrogen bromide in the presence of acetone and an alkaline formate, preferably sodium formate, extracting the reaction mixture thus obtained in two steps with chloroform by adjusting the pH and recovering the product optionally as a halide salt.