WO2004099224A1

WO2004099224A1 - Carboplatin-type platinum (ii) complexes

Info

Publication number: WO2004099224A1
Application number: PCT/EP2004/004680
Authority: WO
Inventors: Henri Brunner; Nick Gruber
Original assignee: Universität Regensburg
Priority date: 2003-05-05
Filing date: 2004-05-03
Publication date: 2004-11-18

Abstract

The invention relates to carboplatinum derivatives, medicaments containing said derivatives and to the use of the carboplatinum derivatives in the production of medicaments for tumour therapy.

Description

Carboplatin-like platinum (II) complexes

The cytostatic effect of cis-diammine (dichloro) platinum (II) (cisplatin), a square-planar complex due to the d ⁸ configuration of the metal, was discovered in the 1960s by chance by B. ROSENBERG. He examined the influence of weak alternating current on the growth of Escherichia coli bacteria and used apparently inert platinum electrodes for this. The result was an inhibition of cell division without simultaneous inhibition of bacterial growth, which led to the formation of long, filamentary cells. In the course of the investigations it was found that not the electrical current itself, but the cis-configured chloro complexes, such as cis-diammine (dichloro) platinum (II) ("cisplatin"), formed in traces by oxidation of the platinum electrode or cis-diammine (tetrachloro) platinum (IV) were responsible for this biological effect.

The cisplatin, which has been approved since 1978, is used as a single preparation or in combination with other synergistic cytostatics such as bleomycin, vinblatin, methotrexate, adriamycin, cyclophosphamide, doxo-rubicin or ethidium bromide against testicular, ovarian, bladder and lung carcinomas and against Tumors used in the neck and head area. The significantly reduced mortality in testicular and bladder cancer is at least partly due to the increased chances of cure for these types of tumors, which increased by over 90%.

In clinical application, cisplatin therapy is associated with a number of serious side effects. The intravenously administered cisplatin leads to immediate side effects such as impairments of the gastrointestinal area (loss of appetite, nausea, vomiting), nephrotoxicity (kidney-damaging effect), ototoxicity (hearing damage), myeloid toxicity (bone marrow-damaging effect) and peripheral neuropathies (peripheral nerve damage) mental stress. The toxicological effects of cisplatin are mainly based on the coordination of platinum to thiol groups of proteins. The dose-limiting factor today is primarily myelotoxicity, since the strong nephroticity can be reduced by additional administration of sulfur compounds such as thiourea or sodium diethyldithiocarbamate, as well as by hydration and mannitol-induced diuresis, because the renal excretion of platinum compounds is accelerated. To alleviate nausea and vomiting, antagonists of dopamine and serotonin are administered, and sulfur compounds such as glutathione can reduce neurotoxic effects.

Another problem with the clinical use of platinum compounds is that which occurs in the tumor cells Resistance to active substances in longer therapy applications. Various mechanisms of resistance development are discussed, such as changes in the transmembrane transport of cisplatin, deactivation of cisplatin by intracellular thiols such as glutathione or metalothionein, improved DNA repair ability, influencing the activity of protein kinase, variations in folate metabolism and in the expression of oncogenes ,

The best analogue to cisplatin has been carboplatin (US 4,657,927), which has been on the market since 1990. Carboplatin shows an efficacy comparable to cisplatin in ovarian, bronchial and cervical carcinomas as well as head and neck tumors. A major advantage of carboplatin is the significantly reduced nephrotoxicity, which no longer plays a role in the dose range used, a lower emetic potential, ie reduction in nausea and vomiting, and the reduced neurotoxicity and ototoxicity. However, this is bought with a higher bone marrow toxicity and associated thrombocytopenia and leukocytopenia. This myelotoxicity is dose-limiting for carboplatin. In contrast to cisplatin, carboplatin carries 1, 1-cyclobutanedicarboxylic acid as a leaving group and is therefore more stable to hydrolysis. The non-coplanar structure of carboplatin due to the tetrahedrally configured spiro-carbon atom may lead to a reduced degradation to damaging derivatives. The half-life in blood plasma at 37 ° C. is 30 hours for carboplatin, but only 1.5 to 3.6 hours for cisplatin (S. Hanessian, J. Wang, Can. J. Chem. 1993, 71, 896).

Cisplatin carboplatin

US Pat. No. 4,657,927 describes platinum (II) malonato complexes with the formula [Pt (II) A _x (OOC) ₂ _CRRι], where A consists of NH ₃ groups (x = 2) and R or Ri each of H atoms, Alkyl, aryl, aralkyl, alkenyl, cycloalkenyl, alkoxy or OH groups can exist or R and Ri with which the C atom can be combined in such a way that cycloalkyl or cycloaklenyl groups and their substituted derivatives be formed. A Cl- and OH-substituted cycloalkyl radical is not mentioned.

Based on this, it is the object of the present invention to provide new carboplatin derivatives which can be used in particular in tumor therapy and which are more effective than those known hitherto.

This object is achieved by the carboplatin derivatives with the feature of claim 1, medicinal products containing carboplatin with the features of claim 16 and the use described in claim 17.

According to the invention, carboplatin derivatives of the general formula I

With

R ¹ to R ^δ independently of one another

H, F, Cl, Br, I, OH, OR 'with R ⁷ = alkyl, aryl, acetyl or acyl, C _n F _{2n +} ι, at least one of the radicals R ¹ to R ⁶ not being H,

R ⁸ and R ⁹ independently of one another NH ₃ ;

NH ₂ R ¹⁰ with R ¹⁰ = alkyl, aryl, rac-1, 2-diaminocyclohexane, RR-1, 2-diaminocyclohexane, SS-1, 2-diaminocyclohexane, H ₂ N-CHR ^{ι: L} -CHR ¹² -NH ₂ with R ¹¹ and R ¹² independently of one another alkyl, aryl, C ₅ H ₄ N-CHR ¹³ -NH ₂ with R ¹³ = H, alkyl, aryl or 1,1'-bipyridyl

provided .

Further preferred compounds can be found in claims 2 to 15.

The inventors could now surprisingly show that by introducing electron-attracting substituents such as. B. halogens or hydroxyl groups in carboplatin the activity profile of such carboplatin derivatives is significantly improved compared to cisplatin and carboplatin.

As is evident from the following investigations, the carboplatin derivative in which R ^{1 is} chlorine is particularly preferred. The invention further relates to medicaments which contain the carboplatin derivatives described above. Of course, the medicinal products contain carriers and auxiliary substances known per se, so that a correspondingly compatible formulation can be produced.

The invention further relates to the use of the carboplatin derivatives according to general formula I for the manufacture of a medicament for tumor therapy. As will be shown below, it has been found that the novel carboplatin derivatives are particularly suitable for this.

The invention is explained in more detail below with the aid of production examples and test results.

Example group 1

Di amminpl atin (II) -Kompl exe

1. Activation of cisplatin

1.1. General

In order to be able to incorporate the diammine platinum (II) fragment into complexes with corresponding leaving groups, it is necessary to convert cisplatin into an activated hydrolysis product. Cisplatin is stirred for one week with the exclusion of light with two molar equivalents of silver nitrate in aqueous solution. The two chloride ligands are replaced by aqua ligands. Silver chloride precipitates and nitrate ions ensure charge balance. The nitrate ions are then exchanged for hydroxide ions by using a strongly see ion exchanger chromatographed. This forms cis-diammine (diaqua) platinum (II) dihydroxide 2, which is taken up for complexation in the solvent mixture water / ethanol (1: 1) (FIG. 1).

1.2. Regulation for diammine (diaqua) platinum (II) dihydroxide (2)

300 mg (1.00 mmol) cisplatin are suspended in 50 ml H ₂ 0 in an ultrasonic bath. A solution of 340 mg (2.00 mmol) of AgN0 ₃ in 10 ml of H ₂ O is added. Then the mixture is stirred at RT for 7 days with the exclusion of light. The precipitated AgCl is suctioned off through a membrane filter, whereby a colorless filtrate is obtained. This is placed on an activated, strongly basic ion exchanger (Merck, ion exchanger III) and the eluate is collected. Activation is carried out by first rinsing the ion exchanger with 100 ml of 2N NaOH and then eluting with H ₂ 0 until the eluate running off has a pH of 9. After the solvent has been stripped off in public transport, a glassy, light-sensitive residue is obtained which can be stored in the dark at -20 ° C for a long period. Only immediately before use is the residue taken up in 50 ml of H ₂ O / EtOH (1: 1).

2. Illustration of the diammine platinum (II) complexes

2.1. General

To complex the 1,1-cyclobutanedicarboxy-lato ligands derived from 3-chloro-1,1-cyclobutanedicarboxylic acid 9 and 3-hydroxy-1,1-cyclobutanedicarboxylic acid 14 with the water-soluble ice To achieve diammine (diaqua) platinum (II) dihydroxide 2, the ligands must be dissolved in water or at least in a water-miscible solvent such as methanol, ethanol, tetrahydrofuran, acetone or dimethylforamide.

In this case, ligands 9 and 14 are dissolved in water. After adding an equimolar amount of diammine (diaqua) platinum (II) dihydroxide solution, the reaction solution is stirred for five days at room temperature with the exclusion of light. The metallic platinum formed is filtered off and the solvent of the filtrate is distilled off to dryness in an oil pump vacuum. The yellowish crude product is recrystallized from water to ¹ cleaning. Care should be taken not to heat, otherwise the complex will decompose. Using this method, the two new carboplatin-like complexes cis-diammine (3-chloro-l, 1-cyclobutanedicarboxylato) plati (II) 89 and cis-diammin (3-hydroxy-1, 1-cyclobutanedicarboxylato) platinum (II) 90 can be synthesized (Fig. 2).

The two complexes 89 and 90 can be isolated in the form of colorless crystals. The water solubility of both compounds is around 18 g-1 ^"1 in the carboplatin range. However, it can clearly be seen that the hydroxy complex 90 is, as expected, more water-soluble than the corresponding chlorine complex 89.

If one compares the synthetic routes of carboplatin and complexes 89 and 90 in terms of their economy, it becomes clear that the compounds 89 and 90 are much more complex to produce than carboplatin. While with carboplatin the cyclobutane dicarboxylic acid fragment can be prepared relatively easily by condensation of 1,3-dibromopropane with malonic acid diethyl ester, the carboplatin-like complexes 89 and 90 are prepared via a multi-stage, complex synthesis.

2.2. Presentation of Cl-Carboplatin (89)

2.2.1. Ligand synthesis

The starting compound for the synthesis of 1,1-cyclobutanedicarboxylic acid dichloride is the commercially available 1,1-cyclobutanedicarboxylic acid. An excess of freshly distilled thionyl chloride is slowly added dropwise to this. The reaction mixture is then heated under reflux with exclusion of moisture until the evolution of gas has ended. The reaction produces the gaseous products 0 ₂ and HCl. Then the excess of thionyl chloride is distilled off on a water bath. The yellowish, liquid crude product is purified by fractional distillation in a water jet vacuum.

For radical chlorination, 1,1-cyclobutanedicarboxylic acid dichloride is slightly warmed with catalytic amounts of AIBN and an equimolar amount of freshly distilled sulphuryl chloride, an exothermic reaction being observed. The orange-colored crude product still contains educt as an impurity and is purified by repeated fractional distillation. It is known that the radical chlorination of 1,1-cyclobutanedicarboxylic acid with sulfuryl chloride has a high selectivity, so that the chlorination takes place practically exclusively in the 3 position. In order to obtain 3-chloro-1,1-cyclobutanedicarboxylic acid, the 3-chloro-1,1-cyclobutanedicarboxylic acid dichloride must be hydrolyzed. For this purpose, a slight excess of water is added to 3-chloro-l, 1-cyclobutanedicarboxylic acid dichloride and gently warmed on the water bath. After a short induction period, an exothermic reaction begins. Extraction of the aqueous phase with diethyl ether enables 3-chloro-l, 1-cyclobutanedicarboxylic acid to be isolated as a colorless solid in good yields.

2.2.2. General complex synthesis

The complexation with the platinum fragment is carried out according to the proven scheme. Cisplatin is stirred for one week with the exclusion of light with two molar equivalents of silver nitrate in aqueous solution. The two chloride ligands are replaced by aqua ligands. Silver chloride precipitates and nitrate ions ensure charge balance. The nitrate ions are then exchanged for hydroxide ions by chromatography over a strongly basic ion exchanger. This forms cis-diammine (diaqua) platinum (II) dihydroxide, which is taken up for complexation in the water / ethanol (1: 1) solvent mixture. First 3-chloro-1, 1-cyclobutanedicarboxylic acid is dissolved in water. After adding an equimolar amount of diammine (diaqua) platinum (II) dihydroxide solution, the reaction solution is stirred for five days at room temperature with the exclusion of light. The gray-black precipitate formed is filtered off and the solvent of the filtrate is distilled off to dryness in an oil pump vacuum. The yellowish crude product is recrystallized from water for purification. Care should be taken not to heat, otherwise the complex will decompose. In this way the new carboplatin-like complex cis-diammine (3-chloro-1, 1-cyclobutanedicarboxylato) platinum (II) (Cl-carboplatin) was presented.

2.2.3. Regulation for cis-diammine (3-chloro-1, 1-cyclobutanedicarboxylato) platinum (II) (89)

71.4 mg (0.4 mmol) of 3-chloro-1,1-cyclobutanedicarboxylic acid are dissolved in 10 ml of H ₂ O. After adding 20 ml (0.4 mmol) of diammine (diaqua) platinum (II) dihydroxide solution 2, the mixture is stirred at RT for 5 d with the exclusion of light. The gray precipitate formed, which contains elemental platinum, is suctioned off through a membrane filter. The solvent of the filtrate is distilled off to dryness and the yellowish crude product is recrystallized from H ₂ 0 / acetone without heating. The resulting colorless crystal needles are dried in public transport.

C ₆ H ₁₁ ClN ₂ 0 ₄ Pt (405.70)

Yield: 90 mg (0.2 mmol, 50%) colorless crystal needles

Mp: 2.10 ° C (C0 ₂ development)

IR (KBr): υ [cm ^"1 ]: 3520-3200 (NH ₃ ); 2960, 2920 (-CH); 1630 (C = 0, carboxylate, antisymmetric valence vibration); 1370 (C = 0, carboxylate, symmetrical valence vibration ).

PI-LISIMS: m / z (%) (glycerol / H ₂ 0): 407 (100), MH ⁺ .

^ -NMR (250 MHz, D ₂ 0, 24 ° C, TMS): δ [ppm] = 4.67 (sb, NH ₃ ), 4.30 (qi, ³ J (H, H) = 7.6 Hz, 1 H, -CH ₂ -CHC1- CH ₂ -), 3.45 / 2.91 (2 m, 4 H, CHCl (CH ₂ ) ₂ C (C0 _2. ) ₂ , symmetrical splitting, diastereotope H).

Elemental analysis: [%] calc. C 17.76, H 2.73, N 6.93; gef. C 18.03, H 2.96, N 6.58.

2.3. Representation of OH-carboplatin (90)

2.3.1. Ligand synthesis

1, 3-Dibromo-2-benzyloxypropane is synthesized by reacting epibromohydrin ((+) -l-bromo-2, 3-epoxypropane) with benzyl bromide and catalytic amounts of HgCl ₂ . The reaction mixture is heated to an internal temperature of 155-160 ° C. for eight hours, during which a dark brown coloration occurs. The product is purified by distillation in an oil pump vacuum. To increase the yield, the forerun, which contains the starting materials, is again heated with HgCl ₂ and worked up accordingly.

For the preparation of 3-benzyloxy-1,1-cyclobutanedicarboxylic acid diethyl ester, malonic acid diethyl ester is alkylated with 1,3-dibromo-2-benzyloxypropane. There were two synthesis variants during the implementation.

The first variant uses the reaction of 1,3-dibromo-2-benzyloxypropane with diethyl malonate in the presence of sodium ethanolate in benzene as solvent. In order to reach the required temperature of 170 ° C with benzene as the solvent, an autoclave is required as the reaction vessel. First, half of the required amount of sodium ethanolate solution is added to the reaction mixture. After a brief heating, the reaction solution is allowed to cool, the rest of the sodium ethanolate solution and a little benzene and heat for a further six hours to 170 ° C. This builds up a pressure of about 10 atm. The neutral solution obtained is separated from the precipitated NaBr by suction and evaporated on a water bath. The NaBr is dissolved in water, the solution extracted with ether and the ethereal extract concentrated. The crude product contained therein is then combined with the main fraction and purified by repeated fractional distillation.

The alternative variant uses the basic effect of sodium hydride. A suspension of sodium hydride in dioxane is slowly added dropwise to 1,3-dibromo-2-benzyloxypropane under nitrogen protection. Then the careful addition of malonic acid diethyl ester takes place, an exothermic reaction starting with evolution of hydrogen. After heating under reflux for 24 hours, a further suspension of sodium hydride in dioxane is added dropwise to the reaction mixture and the mixture is heated for a further 120 hours. The solvent is largely removed from the cooled reaction solution under reduced pressure and the residue is carefully treated with water. Subsequent ether extraction and repeated fractional distillation give diethyl 3-benzyloxy-1,1-cyclobutanedicarboxylate as a yellowish, oily liquid.

It is important for both synthesis strategies that the reactions are carried out with complete exclusion of water in order to maintain the reactivity of sodium ethanolate or sodium hydride.

The hydrogenolytic cleavage of 3-benzyloxy-1,1-cyclobutanedicarboxylic acid diethyl ester takes place in one ethanolic solution with the addition of palladium on activated carbon as a catalyst. Hydrogen is led into the heterogeneous reaction mixture for five days via a gas inlet apparatus. After filtering off the catalyst, the purification is carried out by fractional distillation in an oil pump vacuum. Toluene is produced as a by-product, which can be separated off relatively easily due to the significantly lower boiling temperature of 110 ° C. In this way, 3-hydroxy-1,1-cyclobutanedicarboxylic acid diethyl ester is obtained as a colorless liquid.

In the saponification of 3-hydroxy-1,1-cyclobutanedicarboxylic acid diethyl ester to give 3-hydroxy-1,1-cyclobutanedicarboxylic acid, the proven method for the hydrolysis of substituted malonic acid diethyl esters has proven successful. The ester is refluxed for four hours in a concentrated solution of KOH in ethanol with the addition of water. After the solvent has largely been stripped off, the residue (potassium salt of the dicarboxylic acid) is taken up in a little water and brought to a pH of 1 by dropwise addition of concentrated hydrochloric acid while cooling in an ice bath. The aqueous phase is then extracted with diethyl ether for 20 hours.

2.3.2. Regulation for cis-diammine (3-hydroxy-l, 1-cyclobutanedicarboxylato) platinum (II) (90)

64.0 mg (0.4 mmol) of 3-hydroxy-1,1-cyclobutanedicarboxylic acid are reacted with 20 ml (0.4 mmol) of diammine (diaqua) platinum (II) dihydroxide solution 2 5 d at RT , After distilling off the solvent and recrystallization from water / acetone, the product 90 is obtained in the form of colorless crystal needles. C ₆ H ₁₂ N ₂ 0 ₅ Pt (387.25)

Yield: 74 mg (0.192 mmol, 48%) colorless crystal needles

Mp: 250 ° C (C0 ₂ development)

IR (KBr) υ [cm ^-1 ]: 3280 (NH ₃ , -OH); 2990, 2940, 2890 (-CH); 1630, 1600 (C = 0, carboxylate, antisymmetric valence vibration); 1380, 1350 (C = 0, carboxylate, symmetrical valence vibration).

PI-LISIMS: m / z (%) (glycerol / H ₂ 0): 388 (100), MH ⁺ .

^X H-NMR (250 MHz, D ₂ 0, 24 ° C, TMS): δ [ppm] = 4.67 (sb, NH ₃ , -OH), 4.10 (qi, ³ J (H, H) = 7.6 Hz, 1 H, -CH ₂ -CH (OH) -CH ₂ -), 3.23 / 2.50 (2 m, 4 H, HIGH (CH ₂ ) ₂ C (C0 ₂ -) 2 / symmetrical Splitting, diastereotope H).

Elemental analysis: [%] calcd. C 18.61, H 3.12, N 7.23; found C 18.63, H 3.30, N 6.92.

2.3.3. Molecular structure of cis-diammine (3-hydroxy-1, 1-cyclobutanedicaroxylato) platinum (II) (90)

Crystals suitable for X-ray structure analysis were obtained from cis-diammine (3-hydroxy-l, 1-cyclobutanedicarboxy-lato) platinum (II) (90) by slow crystallization. For this, 90 is dissolved in water and covered with a little acetone. The clear solution is left in the dark at room temperature with the flask open so that the solvent can slowly evaporate. 90 crystallizes in the form of colorless, platelet-shaped crystals. The result of the crystal structure analysis is shown in Fig. 3. The square-planar coordination of Ptl within the scope of the measuring accuracy is clearly recognizable. The six-membered chelate ring has a tub conformation, since the C2 atom and also the Ptl atom have been folded out of plane 01-C1-C3-04 in the same direction. It should also be noted that the cyclobutane ring is not planar, but twisted, and the hydroxyl group is arranged in the equatorial position. This is illustrated by the torsion angle C6-C2-C4-C5 of 20.1 (7) ° (Table 1). The most important binding parameters are summarized in Table 1. Table 1:

When considering the hydrogen bonds, it becomes clear that the molecules in the crystal are arranged in chains. The hydrogen atoms of the NH ₃ groups connect the molecules via the carboxylate oxygen atoms through hydrogen bonds. The specified bond lengths and angles correspond to the values of carboplatin. As with carboplatin, a carbon atom of the cyclobutane ring, the C5 atom, shows a pronounced thermal movement. This can be interpreted as the dynamic folding of the cyclobutane ring. As a consequence, the cyclobutane ring undergoes dynamic inversion between two conformations at room temperature. The bond lengths show that the CO bonds of the chelate ring are about 50 pm longer than those of 02 and 03 and are therefore more of a single bond type. Both are within the characteristic range for CO double bonds. The C5-05 bond length of 1,411 Å is on the order of a single CO bond.

Example group 2

Di aminpl atin (II) -Kompl exe

1. Activation of (+) -trans-1,2-diaminocyclohexane (dichloro) platinum (II) (88)

1.1. Regulation for (±) -trans-1,2-diaminocyclohexane (diaqua) platinum (II) dihydroxide (91)

760 mg (2.00 mmol) of (+) -trans-1,2-diamino-cyclohexane (dichloro) platinum (II) 88 are suspended in 60 ml of H ₂ O in an ultrasonic bath. A solution of 680 mg (4.00 mmol) AgN0 ₃ in 20 ml H ₂ 0 is added. ßend is stirred for 7 d at RT with the exclusion of light. The precipitated AgCl is suctioned off through a membrane filter, whereby a colorless filtrate is obtained. This is placed on an activated, strongly basic ion exchanger (Merck, ion exchanger III) and the eluate is collected. Activation is carried out by first rinsing the ion exchanger with 100 ml of 2N NaOH and then eluting with H ₂ 0 until the eluate running off has a pH of 9. After the solvent has been stripped off in public transport, a glassy, light-sensitive residue is obtained which can be stored in the dark at -20 ° C for a long period. Only immediately before use is the residue taken up in 100 ml of H ₂ O / EtOH (1: 1).

2. Illustration of the diamine platinum (II) complexes

2.1. General

A direct reaction of the cyclobutanedicarboxylato ligands with (±) -trans-1,2-diaminocyclohexane (di-chloro) platinum (II) 88 is not possible for the preparation of the diamine platinum (II) complexes. Here too, as in the case of cisplatin, it is necessary to convert the dichloroplatinum (II) complex 88 into an activated hydrolysis product by reaction with AgN0 ₃ for one week. Chromatography over a strongly basic ion exchanger finally replaces the nitrate ions with hydroxide ions. After the solvent has been stripped off, a glassy residue is obtained which can be stored in the dark at -20 ° C. for several weeks without any signs of decomposition. Shortly before complexation, the residue is taken up in the water / ethanol (1: 1) solvent mixture. In case of gray coloring by elemental platinum, the solution of the activated complex filtered through a membrane filter (Fig. 4).

This activated species 91 is reacted with the cyclobutanedicarboxylato ligands 9 and 14 dissolved in water. The mixture is then stirred for five days at room temperature with the exclusion of light. The metallic platinum that is formed is filtered off through a membrane filter and the solvent of the filtrate is distilled off to dryness in an oil pump vacuum, the heating should not be excessive, since otherwise the complex will decompose. The yellowish crude product is purified by recrystallization from water at room temperature, colorless crystal needles being obtained from complexes 93 and 94 (FIG. 5).

2.2. Regulation for (±) -trans-1,2-diaminocyclohexane (3-chloro-l, 1-cyclobutanedicarboxylato) platinum (II) (93)

You solve 71.43. mg (0.4 mmol) 9 in 20 ml H ₂ 0, drop 20 ml (0.4 mmol) (+) -trans-1, 2-diaminocyclohexane (diaqua) platinum (II) dihydroxide solution 91 and lets stir at RT for 5 d. After filtering off the gray precipitate, the filtrate is evaporated to dryness and the crude product from H ₂ 0 is recrystallized at RT, product 93 being able to be isolated in the form of colorless crystal needles.

Ci ₂ H ₁₉ ClN ₂ θ ₄ Pt (485.83)

Yield: 116.8 mg (0.24 mmol, 60%) colorless crystal needles Mp :> 250 ° C

IR (KBr): υ [cm ^"1 ]: 3260, 3200, 3110 (-NH); 2960, 2880 (-CH); 1630 (C = 0, carboxylate, antisymmetric valence vibration); 1360 (C = 0, carboxylate, symmetrical valence vibration).

PI-ESIMS: m / z (%) (H ₂ 0 + 1% AcOH): 487 (100), MH ⁺ .

^ ^• H-NMR (250 MHz, d ₆ -DMSO, 24 ° C, TMS): δ [ppm] = 5.60 (m, 4 H, -NH ₂ ), 4.31 (qi, ³ J (H , H) = 7.9 Hz, 1 H, -CH ₂ - CHCI-CH2-), 3.50 / 2.80 (2 m, 4 H, CHC1 (CH ₂ ) ₂ C (C0 ₂ -) ₂ , symmetric splitting, diastereotope H), 2.04, 1.81, 1.45, 1.21, 1.02 (5, m 10 H, -C ₆ H ₁₀ -).

Elemental analysis: [%] calc. C 29.67, H 3.94, N 5.77; gef. C 29.26, H 4.07, N 5.50.

2.3. Regulation for (±) -trans-1, 2-diaminocyclohexane (3-hydroxy-l, 1-cyclobutanedicarboxylato) - platinum (II) (94)

65.05 mg (0.4 mmol) 3-hydroxy-l, 1-cyclobutanedicarboxylic acid are mixed in 20 ml H ₂ 0 with 20 ml (0.4 mmol) (+) - trans-1, 2 -diaminocyclohexane (diaqua ) latin (II) - dihydroxide solution 91 5 d at RT.

After distilling off the solvent and recrystallization from water, the product 94 is obtained in the form of colorless crystal needles.

Yield: 46.2 mg (0.10 mmol, 25%) colorless

crystalline needles

Mp: 248 ° C (C0 ₂ development)

IR (KBr): υ [cm ^"1 ]: 3600-3200 (-OH); 3260, 3220, 3120 (-NH); 2960, 2920, 2880 (-CH); 1620 (C = 0, carboxylate, antisymmetric valence vibration ); 1360 (C = 0, carboxylate, symmetrical valence vibration).

PI-ESIMS: m / z (%) (H ₂ 0 + 1% AcOH): 468 (100), MH ⁺ .

^ Η NMR (250 MHz, d ₆ -DMSO, 24 ° C, TMS): δ [ppm] = 5.51 (m, 4 H, -NH ₂ ), 4.91 (sb, 1 H, -OH), 3.84 (qi, ³ J (H, H) = 7.6 Hz, 1 H, -CH ₂ -CH (OH) -CH ₂ -), 3.09 / 2.31 (2 m, 4 H, HO- CH (CH ₂ ) ₂ C (C0 ₂ -) ₂ , symmetrical splitting, diastereotope H), 2.03, 1.80, 1.45, 1.21, 1.01 (5 m, 10 H, -C ₆ Hi).

Elemental analysis: [%] calc. C 30.84, H 4.31, N 5.99; gef. C 30.72, H 4.65, N 5.63.

2.4. Molecular structure of (±) -trans-1, 2-diaminocyclohexane (3-hydroxy-l, 1-cyclobutanedicarboxylato) - platinum (II)

By slow crystallization, complex 94 was able to obtain crystals suitable for X-ray structure analysis. To do this, the compound 94 is dissolved in water and the clear solution is left to stand in the dark at room temperature with the flask open to ensure slow evaporation of the solvent.

The X-ray structure analysis of the colorless crystal needles obtained shows, as would be expected, that the measured crystals are composed of a 1: 1 mixture of the two diastereomers. This finding results from the use of the racemate (+) -trans-1,2-diaminocyclohexane for the complexation in the synthesis of the precursor complex 88, taking into account the spatial arrangement of the OH group on the cyclobutane ring. The result of the X-ray diffractometric examinations is shown in FIG. 6. As with the molecular structure of the carboplatin-like complex 90, the square-planar coordination of Ptl or Pt2 can be clearly seen here. The six-membered chelate ring is also present in the tub conformation, since the C3 atom and also the Ptl atom are folded out of the plane 01-C1-C2-03 in the same direction. The torsion angle C6-C3-C4-C5 of 12.6 (5) ° (Table 2) illustrates the twisting of the cyclobutane ring with the hydroxyl group arranged in the equatorial position. A summary of the most important binding parameters can be found in Table 2. The structural data of the second diastereomer correspond to the given values within the measurement accuracy.

Table 2: Selected structural data of the diamine platinum (II) complex 94.

Binding distances []: Binding angles [°]:

R1-O1 2.033 (5) O1-PH-O3 88.99 (19)

Pt1-O3 2.025 (5) 01-R1-N1 94.5 (2)

R1-N1 2.041 (5) O1-P.1-N2 178.08 (18)

R1-N2 2.027 (6) 03-R1-N1 176.1 (3)

O1-C1 1.304 (8) 03-R1-N2 92.9 (2)

O2-C1 1.224 (9) N1-R1-N2 83.6 (2)

O4-C2 1.224 (7) R1-01-C1 120.6 (4)

O3-C2 1.304 (9) R1-03-C2 121.5 (4)

O5-C5 1.403 (9) C3-C4-C5 90.1 (5)

Torsion angle [°]: hydrogen bonds:

03-R1-O1-C1 -29.7 (5) DH ... A; d (H ... A) [ ^' ]; <DHA [°]

N1-R1-01-C1 152.2 (5) N1-H1A ... O12; 2.0186; 168.72

01-R1-03-C2 43.5 (5) N2-H2A ... 011; 2.0541; 172.33

N2-PH-O3-C2 -136.8 (5) N2-H2B ... O6; 2.4749; 122.72

R1-O1-C1-C3 -15.9 (7) N2-H2B ... O7; 2.0501; 176.39

Pt1-O3-C2-C3 -8.9 (7) N3-H3B ... O3; 2.4332; 131.12

C6-C3-C4-C5 12.6 (5) N3-H3B ... O4; 2.3108; 167.98

In analogy to the structural data of the diammine platinum (II) complex 90, the CO bonds of the chelate ring for compound 94 are also about 80 pm longer than those for 02 and 04 and thus have more single-bond character. However, both bond lengths are within the characteristic range for CO double bonds. 6 the armchair conformation of the cyclohexane ring can also be observed very nicely, the amino substituents being arranged in the more energetically more favorable equatorial position, since in this case no 1, 3 interaction can occur. Example group 3

Pharmacological testing

To determine the inhibition of proliferation, the urothelial carcinoma cell line J82 ([G3]) was selected as an in vitro model.

The T / C value was determined as a measure of the effectiveness.

T / C _corr [%] = ^^ Λ00 [%] C c _σ

T = cell density after exposure to the test substance

C = cell density of the control

C ₀ = initial cell density of the control

The T / C values indicate the percentage inhibition of cell growth in comparison to a reference (only solvents without substance incubation). 0% means that cell growth has stopped, while 100% indicates growth corresponding to the untreated reference. According to the definition of the T / C value, values over 100% are also possible. These signal stimulated cell growth by the active ingredient. Negative values result from a lower cell density than the reference, i.e. H. the substances do not exert a cytostatic, but a cytotoxic effect. Thus, T / C values around 0% indicate optimal effectiveness.

1. In a series of experiments, a single-endpoint assay was carried out with an incubation time of 96 hours. Cl-carboplatin showed a significantly increased especially in the concentrations 5 and 10 μmol. Low growth-inhibiting activity compared to the clinically used carboplatin and OH-carboplatin. Complexes 93 and 94 are also more effective than 92, the (±) -trans-diaminocyclohexane analogue of carboplatin. The results are summarized in Table 3, which shows the T / C values for the carboplatin-like diammine platinum (II) complexes 89 and 90 and the diamine platinum (II) complexes 93 and 94 with carboplatin and 92, the (±) - trans-diaminocyclohexane analogue of carboplatin, as references shows.

Table 3

all tested in water all tested in DMF

A compilation of the test results of complexes 89, 90, 93 and 94 for the concentration 1 μM and 5 μM can be found in FIGS. 7 and 8. Thus, FIG. 7 shows the test results for carboplatin and the carboplatin-like diamminplatin (II). Complexes 89 and 90 and the diamine platinum (II) complexes 92-94 in the concentration 1 μM and FIG. 8 in the concentration 5 μM. While no inhibition of cell division can be observed in the diammine platinum (II) complexes 89, 90 and carboplatin at an active substance concentration of 10 ^"6 mol-1 ^{" 1} , 92 to 94 T / C values of 30 result up to 60%. Even at higher concentrations, the cytostatic activity of the diaminocyclohexane platinum (II) complexes is always greater than that of the diammine analogues. The greatest effectiveness was achieved with chlorine derivatives 89 and 93, respectively. Irradiation does not affect the test results.

In the present study, the platinum complexes with (+) -trans-1, 2-diaminocyclohexane as the non-leaving group showed the highest cytostatic activity. This is not surprising since analogous platinum complexes with (+) -trans-1,2-diaminocyclohexane, such as oxaliplatin, are already being used commercially for tumor therapy.

The carboplatin-like complex 89 was tested like carboplatin in the concentrations 5, 10 and 10 μM. It is particularly interesting that 89 shows almost the same effectiveness as carboplatin at the same concentration. This result correlates with the complex stability in physiological saline solution examined below under 3. Since 89 has less complex stability than carboplatin due to the chlorine substituent, hydrolysis to activated hydroxo complexes takes place much faster. After the leaving group has been split off, the diamminplatin fragment can bind to bionucleophiles more quickly and cause cytostatic activity.

2. In a triple-repeated dose-response study for Cl-carboplatin with carboplatin as a reference in the sense of a kinetic investigation, the T / C value was determined every 24 hours over the course of 125 hours. In all examined concentrations 5, 10 and 20 μmol for Cl-carboplatin results in the almost twice the effectiveness of the clinically used carboplatin. Figures 9a and 9b show the corresponding results.

3. The stability of carboplatin and Cl-carboplatin was examined by ^ Η NMR spectroscopy in aqueous solution. For this purpose, 2.5 • 10 ^"5 mol of the respective complex was dissolved in 1 ml of 0.9% NaCl solution in D ₂ 0, which corresponds to a physiological saline solution, and kept in darkened NMR tubes at room temperature. The course the hydrolysis of the complexes could be followed by recording the NMR spectra (FIGS. 10a and 10b) at the times indicated.

Fig. Shows that in aqueous physiological saline solution of Cl-carboplatin occurred already after one hour of hydrolysis products and in the course of 168 hours, an approximately 40% reduction for ^'cisplatin was. 11 Cl-carboplatin is therefore ^• much more sensitive to hydrolysis than carboplatin. The chlorine substituent reduces the electron density at the oxygen atoms of the carboxylic acid groups and thus influences the rate of substitution. The faster hydrolysis enables a faster release of the cis-diamminplatin (II) fragment, which in turn, through interaction with the DNA bases, influences the processes during cell division and is responsible for the cytostatic properties.

Claims

claims

1. Carboplatin derivatives of the general formula I

With

R ¹ to R ⁶ independently of one another H, F, Cl, Br, I, OH, OR ⁷ with R ⁷ = alkyl, aryl, acetyl or acyl, C _n F _{2n +} ι, with n = 1 to 6, at least one of the Radicals R ¹ to R ^{6 are} not H,

R ^ö and R ^J independently of one another NH ₃ , NH ₂ R ¹⁰ with R ¹⁰ = alkyl, aryl, rac-1, 2-diaminocyclohexane, RR-1, 2-diaminocyclohexane, SS-1, 2-diaminocyclohexane, H ₂ N- CHR ¹¹ -CHR ¹² -NH ₂ with R ^u and R ^{12 are} independently alkyl, aryl, C ₅ H N-CHR ¹³ -NH ₂ with R ¹³ = H, alkyl, aryl or 1, 1'-bipyridyl,

2. Carboplatin derivatives according to claim 1, characterized in that R ¹ = Cl and R ² to R ⁶ H.

3. Carboplatin derivatives according to claim 1, characterized in that R ¹ = OH and R ² to R ⁶ = H.

4. Carboplatin derivatives according to claim 1, characterized in that R ¹ = OR 'with R' = alkyl, aryl, acetyl or acyl and R ² to R ⁶ = H.

5. Carboplatin derivatives according to claim 1, characterized in that R ¹ = F and R ² to R ^δ = H.

6. Carboplatin derivatives according to claim 1, characterized in that R ¹ = Br and R ² to R ⁶ = H.

7. Carboplatin derivatives according to claim 1, characterized in that R ¹ = I and R ² to R ^s = H.

8. Carboplatin derivatives according to claim 1, characterized in that R ¹ = C _n F _{2ll + ι} with n = 1 to 6 and R ² to R ⁶ = H.

9. Carboplatin derivatives according to claim 1, characterized in that R ¹ and R ^{2 are} not H and R ³ to R ⁶ = H.

10. Carboplatin derivatives according to claim 1, characterized in that R ³ = Cl and R ¹ , R ² , R ⁴ to R ⁶

= H are.

11. Carboplatin derivatives according to claim 1, characterized in that R ³ = F and R ¹ , R ² and R ⁴ to R ⁶ = H.

12. Carboplatin derivatives according to claim 1, characterized in that R ³ = C _n F _{2n +} ι with n = 1 to 6 and R ¹ , R ² , and R ⁴ to R ^s = H.

13. Carboplatin derivatives according to claim 1, characterized in that R ³ and R ⁴ = Cl and R ¹ , R ² ,

R ⁵ and R ⁶ = H.

14. Carboplatin derivatives according to claim 1, characterized in that R ² and R ³ = F and R ¹ , R ² , R ⁵ and R ⁶ = H.

15. Carboplatin derivatives according to claim 1, characterized in that R ² and R ³ = C _n F ₂ n ₊ ι with n = 1 to 6 and R ¹ , R ² , R ⁵ and R ⁶ = H.

16. Medicament containing a carboplatin derivative according to any one of claims 1 to 15 and suitable carriers and auxiliaries.

17. Use of the carboplatin derivatives according to any one of claims 1 to 15 for the manufacture of a medicament for tumor therapy.