Dicarboxylic acid-bis(3,5-dicarbamoyl-2-4-6-triiodanilides), process for their preparation and X-ray contrast agents containing them.

The invention relates to new dicarboxylic acid bis (3,5-dicarbamoyl-2,4,6-triiodanilide) of the general formula I.<chemistry id="chem0001" num="0001"><img file="EP0308364A2_D0001.tif" /></chemistry> wherein the amide residues -CONR¹R² and -CONR³R⁴ are different from each other and R¹ is a hydrogen atom, a lower alkyl radical or R², R² is a straight-chain or branched-chain mono- or polyhydroxyalkyl radical, R³ is a hydrogen atom, a lower alkyl radical or R⁴, R⁴ is a straight-chain or branched-chain mono- or polyhydroxyalkyl radical, R⁵ is a hydrogen atom, a lower alkyl radical or a mono- or polyhydroxyalkyl radical and X is a straight-chain or branched-chain alkylene with 1 to 6 carbon atoms, which can, if desired, be substituted by 1 to 6 hydroxyl or alkoxy groups or interrupted by one or more oxygen atoms, means and a method for producing X-ray contrast media which contain compounds of the formula 1 as shading substances.

The radicals R 1 and R 3 preferably contain, as lower alkyl radicals, straight-chain radicals having 1 to 4 carbon atoms, preferably having 1 to 2 carbon atoms, such as, for example, ethyl, propyl, butyl, in particular methyl.

The radicals R² and R⁴ contain 2 to 8 carbon atoms, preferably 2 to 5 carbon atoms, as straight-chain or branched-chain mono- or polyhydroxyalkyl radicals. Straight-chain radicals of R² and R⁴ preferably consist of 2 to 4 carbon atoms, branched-chain radicals preferably contain 3 to 5 carbon atoms. The hydroxyl groups in the radicals R² and R⁴ can be present as primary or secondary hydroxyl groups. The radicals R² and R⁴ can contain 1 to 5 hydroxyl groups, 1 to 3 hydroxyl groups are preferred. Examples of radicals R² and R⁴ are: The 2-hydroxyethyl, 2-hydroxypropyl, 3-hydroxypropyl, 2,3-dihydroxy-propyl, 1-hydroxymethyl-2-hydroxy-ethyl, 2,3-dihydroxybutyl, 2,4-dihydroxybutyl, 2nd , 4-dihydroxybutyl, 3-hydroxy-2- (hydroxymethyl) propyl, 2,3-dihydroxy-1-methylpropyl, 2-hydroxy-3- (hydroxymethyl) butyl, 2,3,4-trihydroxy -butyl-, 2,4-dihydroxy-3- (hydroxymethyl) -butyl-, 3-hydroxy-2,2-bis- (hydroxymethyl) propyl-, 4-hydroxy-3,3-bis- (hydroxymethyl) - butyl-, 4-hydroxy-2,2-bis (hydroxymethyl) butyl, 2-Hydroxy-1,1-bis (hydroxymethyl) ethyl, 1,3-dihydroxy-isopropyl, 2,3-dihydroxy-1-hydroxy-methyl-propyl radical.

The radical R⁵ contains, as the lower alkyl radical, preferably straight-chain alkyl radicals having 1 to 4, preferably having 1 to 2, carbon atoms, such as, for example, the ethyl, propyl or butyl, in particular the methyl radical.

If R⁵ is a mono- or polyhydroxyalkyl radical, it has 2 to 6, preferably 2 to 4, carbon atoms and is substituted by 1 to 5, preferably 1 to 3, hydroxyl groups. The radicals used are, for example, 2-hydroxyethyl, 2,3-dihydroxypropyl. X as a straight or branched chain alkylene, which can be interrupted by one or more oxygen atoms, can contain 1 to 6 carbon atoms. A straight-chain alkylene with 1 to 4 carbon atoms is preferred, which can be interrupted by one or more, preferably by one, two or even three, oxygen atoms.

Examples include: -CH₂-, - (CH₂) ₄-, - (CH₂-CH₂-O-CH₂-CH₂) ₂- and - (CH₂-O-CH₂) ₃-.

The following can be considered as branched-chain radicals X:<img file="EP0308364A2_D0002.tif" />CHCH₃, - [CH₂-C (CH₃) ₂-CH₂] -, - [CH₂-CH (CH₃) -CH₂CH₂] - and the like.

X as a straight or branched chain alkylene can also be substituted by hydroxyl or alkoxy groups. For example, each carbon atom of X can contain a hydroxy or alkoxy group.

Examples include:<chemistry id="chem0002" num="0002"><img file="EP0308364A2_D0003.tif" /></chemistry>

The radical X can also be substituted by hydroxyalkyloxy groups, as in example X = <img file="EP0308364A2_D0004.tif" />CH-O-CH₂CH₂-OH

X-ray contrast media are indispensable aids in the diagnosis of numerous diseases, such as arteriosclerotic vascular processes, tumors, infarcts, diseases of the kidneys and urinary tract. Great progress has been made since the launch of the first products: The chemotoxic properties of the contrast agents have been greatly reduced. For clinical use, this means a reduced occurrence of side effects such as excess, vomiting, certain circulatory reactions, urticaria, bronchospasm and other symptoms up to shock and death. Pharmacologically, chemotoxic effects can be measured, for example, as LD₅₀ after intravenous injection. The products used previously were very hypertonic (eg up to 8 times the osmolality of the blood) and accordingly caused a large number of them serious side effects such as drop in blood pressure, bradycardia up to cardiac arrest, disorders of the blood-brain barrier, severe pain, etc. Newer contrast media only show 2 to 3 times the osmolality of the blood in the clinically common concentrations. Thus, although both the chemotoxicity and the hypertonicity of the contrast media have been reduced, no ideal values ​​have been achieved to date.

Even the latest so-called non-ionic contrast agents still caused serious and serious incidents (McClennan, Radiology <u style="single">162</u>, 1: 1-8 [1987]: "Low-osmolality contrast media: Premises and Promises"), which have to be attributed to chemical-toxic effects.

The osmolality of these products is too high to speak of physiological contrast agents. It is therefore not surprising that at least a certain percentage of patients complain of severe pain when examined with these products ("Pain and hemodynamic effects in aortofemora angiography" in Acta Radiol. Diagnosis 23.4: 389-399 [1982]).

Experience has shown that these problems can largely be solved by the synthesis of water-soluble, very hydrophilic “nonionic dimers”, ie contrast medium molecules which consist of the linking of 2 triiodinated aromatics. Such substances were first described in DOS 26 28 517. Since then, a number of very similar structures have been described, for example in DOS 28 05 928, EP 0023992, EP 0049745 and EP 0108638.

Non-ionic dimers are generally not hypertonic at all concentrations customary for X-ray diagnostics in comparison to body fluids. In addition, some representatives of this class of substances have very low chemotoxicity, ie extremely high LD₅₀ values ​​are achieved after intravenous injection.

Despite these advantages, contrast media based on nonionic dimers have so far hardly been used clinically. The reason for this is the viscosity, in particular of the highly concentrated solutions, which are required for certain particularly critical angiographic examinations. For example, selective angiographic examinations of the coronary arteries and ventricles can only be carried out with contrast medium solutions containing 350 mg iodine / ml or more.

The contrast medium solutions have to be injected at very high speed through approximately 100 cm long, very narrow catheters. Solutions with over 12 to 15 cP at 37 ° C are hardly suitable for this anymore. But also for the very rapid intravenous injection, as is necessary for various modern X-ray techniques, very well tolerated and less viscous contrast agents are required.

The viscosity of the non-ionic dimeric contrast media depends on a number of factors, of which the iodine content of the molecules plays an important role. As the iodine content increases, the viscosity of the solutions of the molecules in question decreases, but at the same time their solubility in water.

It was therefore an object of the present invention to provide highly tolerable and water-soluble contrast media with a high iodine content, which is blood-isotonic at high concentrations and at the same time less viscous.

It was surprising that a comparatively small chemical change compared to the known state of the art led to the compounds of the formula I according to the invention, the aqueous solutions of which, in addition to excellent tolerance and blood isotonia, also have the desired sufficiently low viscosity at a concentration of 300 to 400 mg iodine / ml , to enable universal application in angiography both with rapid addition and with the application of highly concentrated solutions through narrow catheters.

The compounds of the invention differ structurally from the known prior art in that the carbamoyl groups on each benzene nucleus are not the same but different.

The compounds of the general formula I according to the invention are therefore outstandingly suitable as shading substances for the production of or for use in X-ray contrast media. The new compounds have all the properties required by X-ray contrast media. Many, although non-ionic, are very water soluble. The new compounds represent excellently tolerated X-ray contrast media which are suitable for angiography, urography, myelography, lymphography and for the representation of various body cavities and for other radiological examinations.

Due to their weak and neutral taste, some of the compounds are ideal for oral application and for introduction into the lungs.

The bitter and nausea-inducing taste that adheres to the conventional contrast agents can be regarded as a serious disadvantage, particularly in gastrography and bronchography.

The invention thus also relates to new X-ray contrast media based on compounds of the general formula I. The new X-ray contrast media based on the compounds of the general formula I according to the invention are produced in a manner known per se, for example by adding the shading substance to those used in galenics usual additives, e.g. Stabilizers such as sodium edetate, calcium disodium edetate, physiologically compatible buffers, sodium chloride and the like are brought into a form suitable for intravenous application. The concentration of the new X-ray contrast media in the aqueous medium depends entirely on the X-ray diagnostic method. The preferred concentrations and dosages of the new compounds range from 50-500 mg J / ml for the concentration and 5-500 ml for the dosage. Concentrations between 100-400 mg J / ml are particularly preferred.

The invention further relates to a process for the preparation of compounds of the general formula I, which is characterized in that a dicarboxylic acid bis [(3-carbamoyl) - (5-chlorocarbonyl) -2,4,6- triiodanilide)] of the general formula II<chemistry id="chem0003" num="0003"><img file="EP0308364A2_D0005.tif" /></chemistry> wherein R^1′ and R^2′ have the meaning of R¹ and R², where free hydroxyl groups present in R¹ and R² may optionally be present in protected form, X 'has the meaning of X or a substituent to be converted into X. R^5′ has the meaning of a hydrogen atom or a lower alkyl radical and Z is a reactive acid or ester residue, with a base of formula III<chemistry id="chem0004" num="0004"><img file="EP0308364A2_D0006.tif" /></chemistry> implements wherein R^3′ and R^4′ have the meaning of R³ and R⁴, where free hydroxyl groups present in R³ and R⁴ may optionally be present in protected form and then optionally N-alkylate the aromatic acylamino groups, in the case that compounds of the general formula I with R⁵ equal lower alkyl radical are desired, with a compound of general formula IV R⁵-D (IV) and in case that compounds of the general formula I with R⁵ equal to mono- or polyhydroxyl radical are desired, with a compound of the general formula V<chemistry id="chem0005" num="0005"><img file="EP0308364A2_D0007.tif" /></chemistry> implements wherein R⁵ is a lower alkyl group, A represents a hydrogen atom or a mono- or polyhydroxyalkyl radical with 1 to 4 carbon atoms and 1 to 4 hydroxyl groups, B and D either together form an oxido ring or B is a hydroxy group and D represents a chlorine or bromine atom or a sulfate or alkyl sulfate group, and in case that the group X of the compound I denotes a methylene group and all the hydroxyl groups present in the compound I are in protected form, if desired, reacted with a suitable hydroxylating agent and / or the protective groups are removed from protected hydroxyl groups.

For the amidation reaction of the compound of formula II in groups R^1′, R^2′ and X 'present hydroxyl groups are in free or protected form. If these hydroxyl groups are to be present in protected form, all hydroxyl protective groups are known which are known to be suitable for intermediate hydroxyl group protection, ie which are easy to introduce and which can later be split off again with the formation of the ultimately desired free hydroxyl group. Protection by esterification is preferred, for example by introducing the benzoyl or acyl, especially the acetyl radical. Suitable protective groups are also ether groups such as, for example, benzyl, di- and triphenyl-methyl ether groups, and also acetal and ketal groups with, for example, acetaldehyde and acetone.

The amidation of the two carboxyl groups, which are present as reactive acid or ester radical Z, takes place in a suitable solvent at 0 ° to 120 ° C., preferably at 20 ° to 100 ° C. Suitable solvents include polar solvents, such as water, dioxane , Tetrahydrofuran, dimethylformamide, dimethylacetamide, hexametapol, acetone and the like. and their mixtures. Since two moles of acid (from the reactive acid or ester residue) are released in the amidation reaction per converted molecule of the compound of the formula II, which must be neutralized, two equivalents of base are required for each reactive acid or ester group, advantageously in an excess of at least 10%. For practical implementation, the dissolved or suspended starting compound of the formula II is reacted with at least 4.4 equivalents of the base of the formula III or with at least 2.2 equivalents of the base of the formula III and additionally at least 2.2 equivalents of a base different from III, which is then reacted as Proton acceptor is used. Tertiary amines such as, for example, are advantageously used as proton acceptors Triethylamine, tributylamine, pyridine or dimethylaminopyridine or inorganic bases such as sodium bicarbonate, sodium carbonate or the corresponding potassium salts and their hydrates. The inorganic or organic salts obtained in the course of the reaction are separated in a known manner, for example using ion exchangers or by filtration through known adsorbents, such as, for example, Diaion or Amberlite® XAD-2 and 4.

The optionally subsequent N-alkylation of the aromatic acylamino groups to give compounds of the formula I in which R⁵ is a lower alkyl radical or a mono- or polyhydroxyalkyl radical is likewise carried out by methods known to the person skilled in the art, for example in polar solvents such as alkanols or alkane diols such as methanol, ethanol or Propanediol or in polyethers such as ethylene glycol diethyl ether, diethylene glycol dimethyl ether and others or their mixtures in the presence of strong bases, such as the alcoholates of sodium, potassium or their hydrides.

In the case of R⁵ in the meaning of lower alkyl, alkylating agents are compounds of the general formula IV (R⁵-D), such as, for example, the alkyl halides or sulfates or their equivalents such as methyl iodide, methyl bromide or dimethyl sulfate for compounds of the formula I with R mit = methyl or ethyl bromide, ethyl iodide or diethyl sulfate for compounds of formula I with R⁵ = ethyl. For the preparation of compounds of the formula I with R⁵ meaning a mono- or polyhydroxyalkyl radical, alkylating reagents of the general formula V are used<chemistry id="chem0006" num="0006"><img file="EP0308364A2_D0008.tif" /></chemistry> used, wherein A represents a hydrogen atom or a CH₂OH group and B and D either together represent the oxygen atom of an oxidizing ring or B is a hydroxy group and D represents a chlorine or bromine atom or a sulfate or alkyl sulfate group, such as, for example, chloroethanol, alkylene oxide, chloropropanediol (2,3) or 2,3-oxidopropanol at a temperature from room temperature to 80 ° C., preferably at 20 ° C. to 60 ° C. Alkylation reagent and alcoholates are used in excess. For working up, after cooling to room temperature, the mixture is worked up in the customary manner and desalted using ion exchangers.

Another possibility of alkylation is to use the compound I with R⁵ in the meaning of a hydrogen atom with intermediate protected hydroxyl groups in the reaction. As already described for the amidation, this is carried out by customary methods by introducing easily removable groups, for example by etherification (for example introducing the triphenylmethyl radical).

The hydroxyl group protection can also be achieved by ketalization or acetalization, for example using acetaldehyde, acetone, 2,2-dimethoxypropane or dihydropyran.

The later splitting off of the intermediate protective groups with release of the ultimately desired hydroxyl groups also takes place according to methods as already described (see above). To prepare the compounds of the formula I according to the invention with X meaning hydroxymethylene, if desired, the compound of the formula I in which X represents the methylene group and all the hydroxyl groups present are present in protected form with a suitable reagent, for example hydroxylating lead tetraacetate or lead tetrabenzoate oxidize, using indifferent solvents such as dioxane, anhydrous acetic acid or propionic acid is used and the reaction is carried out at 60 ° C. to 100 ° C., preferably at 80 ° C. to 100 ° C. If desired, the hydroxyl protective groups are then split off again. It is also possible to convert a halogen substituent contained in X 'into a hydroxy group in a manner known per se. For example, by the action of alkali or silver salts of lower carboxylic acids in polar solvents at temperatures between 20 and 120 ° C. The intermediates required for the synthesis of the compounds of the general formula II can be prepared by processes known per se, for example from 5-nitroisophthalic acid monoethyl ester, as explained in more detail by the following preparation instructions:

Preparation of 5-amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) amide chloride:

a) 5-nitro-isophthalic acid mono- (2,3-dihydroxy-propyl) -amide

239 g (1 mol) of 5-nitro-isophthalic acid monoethyl ester and 200.4 g (2.3 mol) of 2,3-aminopropanediol are stirred for 2 hours at about 200 mm of mercury and 95 ° C. and the ethanol formed is distilled off in the process. A clear melt is formed from the initially available suspension. The implementation is complete after the specified time. The melt is dissolved in 1 liter of water, the solution is stirred for 30 minutes at 60 ° C. with 24 g of activated carbon, filtered, the filtrate acidified to pH 1 with concentrated hydrochloric acid and inoculated with authentic material. The product crystallized abundantly within 15 hours at room temperature. It is filtered off, washed with 250 ml of water and dried in vacuo at 50 ° C. The yield is 260 g (0.914 mol) = 91.4% of theory.

b) 5-Amino-2,4,6-triiodo-isophthalic acid mono- (2,3-dihydroxy-propyl) -amide

284.2 g (1 mol) of 5-nitro-isophthalic acid mono- (2,3-dihydroxy-propyl) -amide is dissolved in 1 liter of water by adding 100 ml of 33% aqueous ammonia, 4 g of 20% palladium -Calcium carbonate added and the solution or suspension hydrogenated in a 5 liter autoclave within one hour to the corresponding amino compound. The hydrogen pressure is 40 bar at the beginning and 6 bar at the end. The temperature rises to 45 ° C in the meantime. The catalyst is filtered off and the filtrate in which the intermediate 5-amino-isophthalic acid mono- (2,3-dihydroxy-propyl) -amide is dissolved is used in the iodination reaction. For this purpose, the solution is acidified with 150 ml of concentrated hydrochloric acid, heated to 80 ° C. and 1 liter (4 mol) of 4N NaICl₂ solution is added within one hour. After the addition has ended, the mixture is kept at this temperature for a further 3 hours, the heating is then switched off and the mixture is stirred for a further 10 hours. During this time the product crystallizes out. It is suctioned off, suspended in 1 liter of water, mixed with Na₂S₂O₅ until the negative reaction of potassium iodide / starch paper, the crystals are suctioned off, suspended in 2 liters of water, dissolved by adding 32% sodium hydroxide solution, with 60 g of activated carbon for 1 hour Stirred 50 to 60 ° C, filtered, acidified with concentrated hydrochloric acid and recrystallized. The crystals are suction filtered after 10 hours and dried at 50 ° C. in vacuo. The yield is 486.6 g (0.77 mol) = 77% of theory based on the nitro compound used.

c) 5-Amino-2,4,6-triiodoisophthalic acid mono- (2,3-diacetoxypropyl) amide

300 g (0.475 mol) of 5-amino-2,4,6-triiodoisophthalic acid mono- (2,3-dihydroxy-propyl) -amide are suspended in 1.4 liters of ethyl acetate, with 178.07 g (1.74 mol) of acetic anhydride and 5.7 g (47.5 mmol) of 4-dimethylaminopyridine were added and the mixture was heated to boiling. The suspension passes into a solution from which the product quickly crystallizes at the boiling point. The acetylation is complete after 1 hour. The excess acetic anhydride is converted to ethyl acetate by adding ethanol, cooled to room temperature, the crystals are filtered off with suction, washed with ethyl acetate and dried at 50 ° C. in vacuo. The yield is 300.2 g (0.42 mol) = 88.4% of theory.

c) 5-Amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) mono-amide chloride

320 g (0.45 mol) of 5-amino-2,4,6-triiodoisophthalic acid mono- (2,3-diacetoxypropyl) amide are suspended in 1 liter of 1,2-dichloroethane, 107.1 g ( 0.9 mol) thionyl chloride added and heated to boiling temperature. After about 30 minutes there is a clear solution, after 50 minutes the reaction is complete. It is cooled to room temperature, stirred with 5 liters of 5% sodium hydrogen carbonate solution for 15 minutes, the phases are separated and the organic phase is evaporated. 315 g (0.43 mol) = 95.6% of theory of amorphous product are obtained.

Preparation of 5-amino-2,4,6-triiodoisophthalic acid (2-acetoxy-ethyl) monoamide chloride:

a) 5-Amino-2,4,6-triiodo-isophthalic acid (2-acetoxy-ethyl) monoamide

128.8 g (200 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2-hydroxyethyl) monoamide (DOS 16 43 440) are suspended in 1.2 liters of dioxane, 61.25 g (600 mmol) acetic anhydride and 2.44 g (20 mmol) 4-dimethylaminopyridine are added and the suspension is stirred at 80 ° C. After approximately 2 hours there is an almost clear solution and the implementation is complete. The mixture is stirred at room temperature for 12 hours. The product crystallizes out. It is filtered off, washed with dioxane and dried at 50 ° C in a vacuum. The yield is 122.7 g (190.5 mmol) = 95.3% of theory.

b) 5-Amino-2,4,6-triiodoisophthalic acid (2-acetoxy-ethyl) monoamide chloride

117.2 g (181.94 mmol) of 5-amino-2,4,6-triiodoisophthalic acid- (2-acetoxy-ethyl) -monoamide are suspended in 586 ml of dichloroethane, 64.94 g (545.82 mmol) Thionyl chloride added and the suspension heated to boiling. After 45 minutes there is a clear solution, after 55 minutes the sulfinylimide of the product begins to crystallize from it. The conversion is complete after 2 hours. It is cooled to room temperature, the crystals are filtered off with suction, suspended in 400 ml of dichloroethane, 49.4 g (172.7 mmol) of soda decahydrate are added to this suspension and the suspension is stirred for 5 hours at room temperature. The solid is then filtered off and boiled with 1 liter of tetrahydrofuran for 2 hours. The product goes into solution and inorganic salts remain undissolved. The tetrahydrofuran solution is concentrated to about 500 ml, the product separating out in crystalline form. The yield is 106.73 g (161 mmol) = 88.6% of theory.

The subsequent dimerization to give the compounds of the general formula II is carried out using processes known from the literature (for example EP 0 033 426)

example 1

Malonic acid bis [3- (2,3-dihydroxy-N-methyl-propylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N-methylanilide]

a) Malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide]

79.3 g (108 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) amide chloride are dissolved in 250 ml of toluene, the solution is heated to 90 ° and 8.81 g (50 mmol) malonyl chloride added. A bright crystalline precipitate is formed quickly. After 15 minutes the heating is removed and the mixture is allowed to come to room temperature. The crystalline reaction product is filtered off with suction, washed with toluene and dried at 50 ° C. in vacuo. The yield is 69.8 g (45.4 mmol) = 84.1% of theory.

b) Malonic acid bis [3- (2,3-dihydroxy-N-methyl-propylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-anilide]

65 g (42.3 mmol) malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide] are dissolved in 650 ml acetone, with 36.3 g ( 126.9 mmol) of soda decahydrate and 13.3 g (126.9 mmol) of N-methyl-aminopropanediol-2,3 were added and the suspension was refluxed for 2 hours. The reaction mixture is then cooled to room temperature, the solid precipitate is filtered off with suction, the filtrate is evaporated, the residue is dissolved in 300 ml of water, saponified with pH-controlled sodium hydroxide solution, neutralized with hydrochloric acid and desalted on ion exchangers. The aqueous eluate from the ion exchanger is evaporated to dryness. The yield is 58.62 g (38.9 mmol) = 92% of theory. Amorphous solid.

c) Malonic acid bis [3- (2,3-dihydroxy-N-methylpropylcarbamoyl) -5- (2,3-dihydroxypropylcarbamoyl) -2,4,6-triiodo-N-methylanilide]

1.48 g (64.3 mmol) of sodium are dissolved in 62 ml of methanol, the solution is mixed with 62 ml of 1,2-propanediol, in this solution 23.1 g (15.3 mmol) of malonic acid bis [3- ( 2,3-dihydroxy-N-methyl-propylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodoanilide] dissolved and stirred at 50 ° C for 4 hours. The methanol is then distilled off at atmospheric pressure, 7.72 g (61.2 mmol) of dimethyl sulfate are added and the mixture is stirred at 50 ° C. for 20 hours. The reaction solution is then cooled to room temperature, precipitated in 1 liter of acetone, the precipitate is filtered off with suction, dissolved in water and desalted on an ion exchanger. The eluate is evaporated to the amorphous solid. The yield is 21.12 g (13.8 mmol) = 90% of theory.

Example 2

Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- [bis (2-hydroxyethyl) carbamoyl] -2,4,6-triiodo-N-methyl-anilide}

a) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- [bis (2-hydroxyethyl) carbamoyl] -2,4,6-triiodoanilide}

153.7 g (100 mmol) of malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide] are dissolved in 1537 ml of acetone at room temperature, the solution with 85.84 g (300 mmol) of soda decahydrate were added and a solution of 31.54 g (300 ml) of diethanolamine in 100 ml of acetone was added dropwise to this suspension over the course of about 15 minutes. The suspension is then refluxed for 1.5 hours. After this time, the implementation is complete. The solid soil is suctioned off, the filtrate is concentrated to an oil, this oil is dissolved in 300 ml of water and kept at pH 12 with 32% sodium hydroxide solution at pH 12 until the pH remains at 12 and the thin-layer chromatography completely saponifies of the acetate groups. The aqueous solution is neutralized with aqueous hydrochloric acid and desalted on ion exchangers. The aqueous eluate is evaporated to dryness. The yield is 130 g (86.3 mmol) = 86.3% of theory as a colorless amorphous solid.

b) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- [bis (2-hydroxyethyl) carbamoyl] -2,4,6-triiodo-N-methyl-anilide}

4.6 g (200 mmol) of sodium are dissolved in a mixture of 200 ml of methanol and 200 ml of 1,2-propanediol, this solution 75.3 g (50 mmol) of malonic acid bis {3- (2,3-dihydroxy- propylcarbamoyl) -5- [bis (2-hydroxyethyl) carbamoyl] -2,4,6-triiodoanilide} was added, the mixture was stirred at 50 ° C. for 3 hours and the methanol was then distilled off at atmospheric pressure. The reaction solution is then mixed with 28.67 g (200 mmol) of methyl iodide and stirred at 50 ° C. for 24 hours. The thin layer chromatography then indicates complete conversion. The reaction solution is cooled to room temperature, stirred into 2 liters of acetone, the amorphous precipitate of the product is filtered off with suction, dissolved in water and the solution is desalted using ion exchangers. The aqueous eluate evaporated to dryness gives 60.2 g (39.25 mmol) = 78.5% of theory of a colorless amorphous solid.

Example 3

Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5 - [(1RS, 2SR) -2,3-dihydroxy-1-hydroxymethylpropyl-carbamoyl] -2,4,6-triiodo-N-methyl- anilide}

a) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5 - [(1RS, 2SR) -2,3-dihydroxy-1-hydroxymethylpropyl-carbamoyl] -2,4,6-triiodo-anilide}

153.7 g (100 mmol) of malonic acid bis {3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide] are dissolved in 1.52 liters of acetone at room temperature, 85 , 84 g (300 mmol) of soda decahydrate and 48.36 g (300 mmol) of 6-amino-2,2-dimethyl-1,3-dioxepin-5-ol were added and the mixture was boiled under reflux for 2 hours. The reaction mixture is then cooled to room temperature, the solid precipitate is filtered off with suction, the filtrate is evaporated, the residue is dissolved in 300 ml of water and the acetate groups at pH 12 and the ketals at pH 1 are hydrolyzed under pH control. The solution is then neutralized and desalted on ion exchangers. The aqueous eluate is evaporated to dryness and gives 134.28 g (87.3 mmol) = 87.3% of the theory amorphous solid.

b) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5 - [(1RS, 2SR) -2,3-dihydroxy-1-hydroxymethylpropyl-carbamoyl] -2,4,6-triiodo-N- methyl anilide}

9.2 g (400 mmol) sodium are dissolved in a mixture of 400 ml methanol and 400 ml 1,2-propanediol, this solution 153.8 g (100 mmol) malonic acid bis {3- (2,3-dihydroxy- propylcarbamoyl) -5 - [(1RS, 2SR) -2,3-dihydroxy-1-hydroxymethylpropyl-carbamoyl] -2,4,6-triiodo-anilide}, stirred for 3 hours at 50 ° C. and the methanol then at normal pressure distilled off. The reaction solution is then mixed with 57.35 g (400 mmol) of methyl iodide and stirred at 50 ° C. for 24 hours. The DC then shows complete implementation. The reaction solution is cooled to room temperature, stirred into 4 liters of acetone, the amorphous precipitate of the product is filtered off with suction, dissolved in water and the aqueous solution is desalted using ion exchangers. The eluate evaporated to dryness gives 116.84 g (74.6 mmol) = 74.6% of theory of a colorless amorphous solid.

Example 4

Malonic acid bis [3- (2-hydroxy-N-methyl-ethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N- (2-hydroxy-ethyl) - anilide]

a) Malonic acid bis [3- (2-hydroxy-N-methyl-ethyl-carbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl] -2,4,6-triiodo-anilide]

153.7 g (100 mmol) of malonic acid bis [3-chlorocarbonyl-5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodoanilide] are dissolved in 1.52 liters of acetone at room temperature, 85 , 84 g (300 mmol) of soda decahydrate and 22.53 g (300 mmol) of N-methylethanolamine are added and the mixture is boiled under reflux for 2 hours. The suspension is then cooled to room temperature, the solid precipitate is filtered off with suction, the filtrate is evaporated, the residue was dissolved in 300 ml of water and the acetate groups were saponified at pH 12 at 50 ° C. under pH control. The solution is then neutralized and desalinated on ion exchangers. The aqueous eluate is evaporated to dryness and gives 109.1 g (75.5 mmol) = 75.5% of theory of a colorless amorphous solid.

b) Malonic acid bis [3- (2-hydroxy-N-methyl-ethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiod-N- (2-hydroxy-ethyl ) -anilide]

4.29 g (186.76 mmol) of sodium are dissolved in a mixture of 193 ml of methanol and 193 ml of 1,2-propanediol, 64.3 g (44.46 mmol) of malonic acid bis [3- (2-hydroxy- N-methyl-ethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-anilide] is added, the solution is stirred at 50 ° C. for 3 hours and the methanol is then distilled off at atmospheric pressure. 14.61 g (177.84 mmol) of chloroethanol are then added to the reaction solution and the mixture is stirred at 50 ° C. for 24 hours. The thin layer chromatography then shows complete conversion. The reaction solution is cooled to room temperature, stirred into 3 liters of acetone, the amorphous precipitate of the product is filtered off with suction, dissolved in water and the aqueous solution is desalted in ion exchangers. The eluate evaporated to dryness gives 51.57 g (33.68 mmol) = 75.7% of theory of a colorless amorphous solid.

Example 5

Malonic acid bis [3- (2,3-dihydroxy-N-methyl-propyl-carbamoyl) -5- (2-hydroxy-ethylcarbamoyl] -2,4,6-triiodo-N-methyl-anilide]

a) Malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo- (2-acetoxy-ethylcarbamoyl) anilide

155.9 g (235.4 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2-acetoxy-ethyl) monoamide chloride are suspended at room temperature in 780 ml of dioxane, heated to 80 ° C. until one Solution has arisen. 20.32 g (141.2 mmol) of malonyl chloride are added and the mixture is stirred at 80 ° C. for 12 hours. During this time, the product increasingly crystallized out of the reaction solution. It is cooled to room temperature, the crystals are filtered off with suction, washed with dioxane and dried at 50 ° C. in vacuo for 24 hours. The yield is 123.26 g (88.5 mmol) = 75.2% of theory.

b) Malonic acid bis [3- (2,3-dihydroxy-N-methylpropylcarbamoyl) -5- (2-hydroxyethylcarbamoyl] -2,4,6-triiodoanilide]

69.64 g (50 mmol) of malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo- (2-acetoxyethylcarbamoyl) anilide] are dissolved in 105 ml of dimethylformamide and at room temperature this solution is dissolved in 10 ml of DMF Mixture of 15.78 g (150 mmol) of 1,2-N-methylaminopropanediol and 15.18 g (150 mmol) of triethylamine was added dropwise. After four hours of stirring at room temperature, the reaction is complete. The hydrochloride of the triethylamine is filtered off, the filtrate is stirred into 2 liters of methylene chloride, the precipitate of the product is filtered off with suction, dissolved in 200 ml of water, this solution is saponified at 50 ° C. and pH 12, neutralized with hydrochloric acid and desalted in ion exchangers. The eluate evaporated to dryness gives 56.1 g (38.8 mmol) = 77.6% of theory of a colorless amorphous solid.

c) Malonic acid bis [3- (2,3-dihydroxy-N-methyl-propyl-carbamoyl) -5- (2-hydroxy-ethylcarbamoyl) -2,4,6-triiod-N-methyl-anilide]

4.6 g (200 mmol) of sodium are dissolved in a mixture of 200 ml of methanol and 200 ml of 1,2-propanediol, the solution 72.3 g (50 mmol) of malonic acid bis [3- (2,3-dihydroxy- N-methyl-propyl-carbamoyl) -5- (2-hydroxyethylcarbamoyl) -2,4,6-triiodo-anilide] was added, the solution was stirred for 3 hours at 50 ° C., the methanol was then distilled off at normal pressure, 28. 4 g (200 mmol) of methyl iodide were added and the mixture was stirred at 50 ° C. for 24 hours. According to thin layer chromatography, the reaction is complete after this time. The reaction solution is cooled to room temperature, stirred into 3 liters of acetone, the precipitate of the product is filtered off with suction, dissolved in water and the aqueous solution is desalted using ion exchangers. The eluate evaporated to dryness contains 60.06 g (39.15 mmol) = 78.3% of theory of a colorless amorphous solid.

Example 6

Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl) -2,4,6-triiodo-N- (2,3-dihydroxy-propyl) anilide}

a) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl] -2,4,6-triiodo-anilide}

100 g (68.45 mmol) malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide] are dissolved in 1000 ml acetone, the solution with 59.54 g ( 208.1 mmol) of soda decahydrate were added and 11.29 g (184.82 mmol) of ethanolamine, dissolved in 50 ml of acetone, were added dropwise to this suspension over the course of about 15 minutes. When the addition of the amine has ended, the suspension is boiled under reflux for 2 hours. The reaction was then complete according to thin layer chromatography, the product is in the precipitate of the inorganic salts. The precipitate is filtered off with suction, suspended in water, the intermediate which is sparingly soluble in water is suctioned off, the filter residue is suspended in water, saponified with sodium hydroxide solution, neutralized, the aqueous solution is desalted in ion exchangers and the eluate is evaporated to dryness. Yield 84.73 g (59.76 mmol) = 87.3% of theory as a colorless amorphous solid.

b) Malonic acid bis {3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl) -2,4,6-triiodo-N- (2,3-dihydroxy-propyl) anilide}

9.2 g (400 mmol) of sodium are dissolved in a mixture of 400 ml of methanol and 400 ml of 1,2-propanediol, this solution 141.8 g (100 mmol) of malonic acid bis {3- (2,3-dihydroxy- propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl) -2,4,6-triiodo-anilide}, the mixture was stirred at 50 ° C. for 3 hours and the methanol was then distilled off at atmospheric pressure. The reaction solution is mixed with 32.86 g (300 mmol) of 2,3-chloropropanediol and stirred at 50 ° for 24 hours. The implementation is complete according to thin layer chromatography. For working up, the reaction solution is stirred into 4 liters of acetone, the precipitate of the product is filtered off with suction, dissolved in water, desalted on ion exchangers, and the aqueous eluate is evaporated to dryness. The result is 127.2 g (81.2 mmol) = 81.2% of theory of the product as a colorless amorphous solid.

Example 7

Hydroxymalonic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl) -2,4,6-triiodo-N- (2,3-dihydroxy-propyl) anilide]

a) Acetoxymalonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide]

73.4 g (100 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) amide chloride are dissolved in 250 ml of toluene, the solution is heated to 90 ° C. and 10. 12 g (55 mmol) acetoxymalonic acid dichloride (produced in analogy to O-acetyl-lactyl chloride, Filachione et al. JACS <u style="single">72</u>, 410 [1950]). A crystalline precipitate of the product quickly forms. After 15 minutes, the heating bath is removed, cooled to room temperature, the crystals are suction filtered, washed with toluene and dried at 50 ° in vacuo. The yield is 55.97 g (36.9 mmol) = 73.8% of theory.

b) Hydroxymalonic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethyl-carbamoyl] -2,4,6-triiodo-anilide]

84.95 g (56 mmol) of acetoxymalonic acid bis [3- (2,3-diacetoxypropylcarbamoyl) -5-chlorocarbonyl-2,4,6-triiodoanilide] are dissolved in 170 ml of dioxane, 41, .66 g (145.6 mmol) of soda decahydrate and 8.9 g (145.6 mmol) of ethanolamine were added and the mixture was refluxed for 2 hours. The reaction mixture is then cooled to room temperature, the precipitate is filtered off with suction, the filtrate is evaporated, the residue is dissolved in 250 ml of water, saponified under pH control at 50 ° C. with concentrated sodium hydroxide solution, neutralized with hydrochloric acid and desalted on ion exchangers. The aqueous eluate is evaporated to dryness. The yield is 71 g (49.5 mmol) = 88.4% of theory.

c) Hydroxymalonic acid bis [3- (2,3-dihydroxy-propyl-carbamoyl) -5- (2-hydroxyethyl-carbamoyl] -2,4,6-triiodo-N- (2,3-dihydroxy-propyl) - anilide]

4.6 g (200 mmol) sodium are dissolved in a mixture of 200 ml methanol and 200 ml 1,2-propanediol, this solution 71.7 g (50 mmol) hydroxymalonic acid bis [3- (2,3-dihydroxy- propyl-carbamoyl) -5- (2-hydroxyethyl-carbamoyl) -2,4,6-triiodo-anilide] was added, the mixture was stirred at 50 ° C. for 3 hours and the methanol was then distilled off at atmospheric pressure. The reaction solution is then mixed with 16.43 g (150 mmol) of 2,3-chloropropanediol and stirred at 50 ° C. for 24 hours. For working up, the mixture is stirred into 3 liters of methylene chloride, the precipitate is filtered off with suction, dissolved in 200 ml of water, desalted on ion exchangers, the eluate is evaporated to dryness and the residue is dried at 50 ° C. in vacuo. The yield is 60.91 g (38.5 mmol) = 77% of theory.

Example 8

Hydroxymalonic acid bis⁸3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl) -2,4,6-triiod-N-methyl-anilide⁹

a) Hydroxymalonic acid bis⁸3- (2-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl) -2,4,6-triiodo-anilide⁹

75.85 g (50 mmol) acetoxymalonic acid-bis⁸3- (2,3-diacetoxypropyl-carbamoyl) -5-chlorocarbonyl-2,4,6-triiodoanilide an are dissolved in 150 ml dioxane, 37.2 g (130 mmol) of soda decahydrate and 11.84 g (130 mmol) of serinol were added and the mixture was refluxed for 2 hours. The reaction mixture is then cooled to room temperature, the solid is filtered off with suction, the filtrate is evaporated, the residue is dissolved in 250 ml of water, saponified under pH control at 50 ° C. with concentrated sodium hydroxide solution, neutralized with hydrochloric acid and desalted on ion exchangers. The aqueous eluate evaporated to dryness contains 64.62 g (43.25 mmol) = 86.5% of theory of a colorless solid.

b) Acetoxymalonic acid bis⁸3- (2-acetoxy-1-acetoxymethylethyl-carbamoyl) -5- (2,3-diacetoxy-propyl-carbamoyl) -2,4,6-triiodo-anilide⁹

112.06 g (75 mmol) of hydroxymalonic acid bis⁸3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl) -2,4,6-triiodo-anilide⁹ are in 300 ml of ethyl acetate, 137.8 g (1.35 mol) of acetic anhydride and 1.65 g (13.5 mmol) of 4-dimethylamino-pyridine were added and the mixture was boiled under reflux for 5 hours. Then there is a clear solution and the implementation is quantitative. This solution is mixed with 31.1 g (0.675 mol) of ethanol and refluxed for a further hour. Then the solvent is largely distilled off, the residue is stirred with 300 ml of water, and the solid product is filtered off and dried. Yield 115.6 g (61.7 mmol) = 82.3% of theory.

c) Hydroxymalonic acid bis⁸3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl) -2,4,6-triiodo-N-methyl-anilide⁹

4.6 g (200 mmol) sodium are dissolved in a mixture of 200 ml methanol and 200 ml ethylene glycol dimethyl ether, 93.62 g (50 mmol) acetoxymalonic acid bisal3- (2-acetoxy-1-acetoxymethylethyl-carbamoyl) -5 (2nd , 3-diacetoxy-propyl-carbamoyl) -2,4,6-triiodo-anilide⁹ added, stirred for 3 hours at 50 ° C, the methanol was then distilled off at normal pressure, 21.3 g (150 mmol) of methyl iodide were added and Stirred at 50 ° C for 24 hours. The reaction solution is then filtered, the filtrate evaporated, the residue suspended in water, saponified with sodium hydroxide solution, neutralized, the solution desalted on ion exchangers and the eluate evaporated to dryness. 55.25 g (36.3 mmol) = 72.6% of theory of a colorless solid are obtained.

Example 9

Malonic acid bis [3- (2-hydroxy-N-methyl-ethylcarbamoyl) -5- (2,3-dihydroxy-propyl-carbamoyl) -2,4,6-triiodo-N- (2-hydroxy-ethyl) - anilide]

a) Hydroxymalonic acid bis [3- (2-acetoxy-N-methyl-ethylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo-N- (2-acetoxy-ethyl) - anilide]

76.78 g (50 mmol) malonic acid bis [3- (2-hydroxy-N-methyl-ethylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N- (2nd -hydroxy-ethyl) -anilide] (see Example 4) are suspended in 400 ml of dioxane, 122.5 g (1.2 mol) of acetic anhydride and 0.61 g (5 mmol) of 4-dimethylaminopyridine are added and the mixture is heated to 80.degree . After about 1 hour there is a clear solution, after 2 hours the acetylation is complete. The excess acetic anhydride is converted into ethyl acetate by adding 36.85 g (800 mmol) of ethanol, the solution is concentrated under reduced pressure and the concentrate is stirred into 2 liters of water. The resulting flaky precipitate is filtered off, washed with water and dried in vacuo at 50 ° C. The yield is 80.8 g (43.2 mmol) = 86.4% of theory.

b) Hydroxymalonic acid bis [3- (2-hydroxy-N-methyl-ethylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N- (2-hydroxy-ethyl) - anilide]

74.8 g (40 mmol) malonic acid bis [3- (2-acetoxy-N-methyl-ethylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo-N- (2nd -acetoxy-ethyl) -anilide] are dissolved in 250 ml of acetic acid, the solution is heated to 100 ° C. and 17.73 g (40 mmol) of lead tetraacetate are added in several portions in about 45 minutes. After the addition has ended, the mixture is kept at 100 ° C. for a further 2 hours. A portion of the acetic acid is then distilled off under reduced pressure, the concentrated solution is cooled to room temperature and stirred into 3 liters of water. The product precipitates as a flaky precipitate. This is suctioned off, washed with water and dissolved in 300 ml of ethanol while still moist with water. 32% sodium hydroxide solution is added to this solution at 50 ° C. until thin layer chromatography indicates the complete hydrolysis of the acetyl groups. The solution is then neutralized, the ethanol largely distilled off under reduced pressure, replaced by 200 ml of water and this solution desalted on ion exchangers. Evaporation of the aqueous eluate gives 38.13 g (24.6 mmol) = 61.5% of the theoretical product.

Example 10

Methoxymalonic acid bis [3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiod-N-methyl-anilide]

a) Methoxymalonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide]

73.4 g (100 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) amide chloride is dissolved in 250 ml of toluene, the solution is heated to 90 ° C. and 8. 52 g (55 mmol) methoxymalonyl chloride added dropwise. A crystalline precipitate of the product quickly forms. After 15 minutes, the heating bath is removed, cooled to room temperature, the crystals are suction filtered, washed with toluene and dried at 50 ° C. in vacuo. The yield is 57.07 g (38.15 mmol) = 76.3% of theory.

b) Methoxymalonic acid bis [3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-anilide]

74.8 g (50 mmol) of methoxymalonic acid bis [3-chlorocarbonyl-5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodoanilide] are dissolved in 150 ml of dioxane, 37.2 g ( 130 mmol) of soda decahydrate and 11.84 g (130 mmol) of serinol were added and the mixture was stirred at 50 ° C. for 2 hours. The reaction mixture is then cooled to room temperature, the solid is filtered off with suction, the filtrate is evaporated, the residue is dissolved in 250 ml of water, saponified with concentrated sodium hydroxide solution at 50 ° C., neutralized with hydrochloric acid and desalted on ion exchangers. The aqueous eluate evaporated to dryness contains 66.58 g (44.15 mmol) = 88.3% of theory of colorless amorphous solid.

c) methoxymalonic acid bis [3- (2-hydroxy-1-hydroxymethylethyl-carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiod-N-methyl-anilide]

4.6 g (200 mmol) sodium are dissolved in a mixture of 200 ml methanol and 200 ml 1,2-propanediol, 75.4 g (50 mmol) methoxymalonic acid bis [3- (2-hydroxy-1-hydroxymethylethyl- carbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2, 4,6-triiodo-anilide] was added, the mixture was stirred at 50 ° C. for 3 hours, the methanol was then distilled off under atmospheric pressure, and the remaining solution was 21.3 g ( 150 mmol) of methyl iodide were added and the mixture was stirred at 50 ° C. for 24 hours. The reaction solution is then cooled to room temperature and stirred into 2 liters of methylene chloride. The product precipitates as a pasty mass. This is decanted, dissolved in 200 ml of water and desalted on ion exchangers. 56.4 g (36.7 mmol) = 73.4% of theory of the title compound were obtained as an amorphous solid.

Example 11

2,3-dihydroxysuccinic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethylcarbamoyl) -2,4,6-triiodo-N- (2-hydroxyethyl) anilide]

a) 2,3-diacetoxy-succinic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) anilide]

73.4 g (100 mmol) of 5-amino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) amide chloride are dissolved in 250 ml of toluene, the solution is heated to 90 ° C. and 14.91 g (55 mmol) 2,3-diacetyl succinic acid dichloride (preparation according to D. Seebach et al. Ber. <u style="single">1980</u>, 1691) added. A crystalline precipitate of the product quickly forms. After 30 minutes, the mixture is cooled to room temperature and the crystals are filtered off with suction, washed with toluene and dried at 50 ° C. in vacuo. The yield is 59.43 g (35.65 mmol) = 71.3% of theory.

b) 2,3-dihydroxysuccinic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethylcarbamoyl) -2,4,6-triiodoanilide]

75.02 g (45 mmol) of 2,3-diacetoxy-succinic acid bis [3- (2,3-diacetoxypropylcarbamoyl) -5-chlorocarbonyl-2,4,6-triiodoanilide] are dissolved in 250 ml of dioxane, 15 , 7 g (67.5 mmol) of soda decahydrate and 4.12 g (67.5 mmol) of ethanolamine were added and the mixture was stirred at 50 ° C. for 2 hours. The suspension is then cooled to room temperature, the precipitate is filtered off with suction, the filtrate is evaporated, the residue is suspended in 250 ml of water, saponified at 50 ° C. under pH control with concentrated sodium hydroxide solution, neutralized with hydrochloric acid and desalted on ion exchangers. The aqueous eluate is evaporated to dryness and gives 57.65 g (39.4 mmol) 87.6% of the theory of the compound.

c) 2,3-dihydroxysuccinic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethylcarbamoyl) -2,4,6-triiodo-N- (2-hydroxyethyl) -anilide]

4.6 g (200 mmol) of sodium are dissolved in a mixture of 200 ml of methanol and 200 ml of 2,3-propanediol. 73.2 g (50 mmol) of 2,3-dihydroxysuccinic acid bis [3- (2,3-dihydroxy-propylcarbamoyl) -5- (2-hydroxyethylcarbamoyl) -2,4,6-triiodo-anilide] was added, the mixture was stirred at 50 ° C. for 3 hours and the methanol was then distilled off at atmospheric pressure. The reaction solution is then mixed with 12.1 g (150 mmol) of chloroethanol and stirred at 50 ° C for 24 hours. To isolate the product, after cooling to room temperature, the reaction solution is precipitated in 3 liters of methylene chloride, the precipitate is filtered off with suction, dissolved in water and desalted on ion exchangers. The eluate evaporated to dryness gives 81.2 g (52.3 mmol) of 72.3% of theory of the desired compound.

EXAMPLE 12

Hydroxymalonic acid bis [3- (2,3-dihydroxy-N-methyl-propylcarbamoyl) -5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N-methyl-anilide]

a) 5-Methylamino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) monoamide chloride

122 g (200 mmol) of 5-methylamino-2,4,6-triiodoisophthalic acid dichloride are dissolved in 400 ml of dioxane, 71.5 g (250 mmol) of Na₂CO₃ decahydrate and 18.2 g (200 mmol) of 2.3 -Dihydroxy-propylamine added and the mixture stirred for 3 hours at room temperature. The precipitate is then suction filtered, the filtrate is evaporated to a foam, this is taken up in 200 ml of dioxane, 36.75 g (360 mmol) of acetic anhydride and 2.44 g (20 mmol) of 4-dimethylamino-pyridine are added and the mixture is stirred at 80 ° for 3 hours C stirred. A homogeneous solution is created. The reaction solution is evaporated in vacuo to a foam, this is dissolved in 200 ml of acetone and chromatographed on 2 kg of silica gel 60 (Merck) with hexane / ethyl acetate (ethyl acetate fraction 20-&gt; 50% linearly increased). The corresponding fractions are combined and, after evaporation, give 65.12 g (87 mmol) = 43.5% of theory of the compound as an amorphous solid.

b) benzyloxy-malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) -N-methyl-anilide]

60 g (80 mmol) of 5-methylamino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) monoamide chloride are suspended in 600 ml of toluene and the suspension is heated to 100.degree. A clear solution is created. 9.88 g (40 mmol) of benzyloxymalonic acid dichloride (prepared analogously to Hammond et al., Soc.<u style="single">1957</u>, 1062) added. After a few minutes, the bisanilide precipitates out as a crystalline precipitate. After 30 minutes, the heating is removed, the mixture is cooled to room temperature, the precipitate is filtered off with suction and dried at 50 ° C. in vacuo for 24 hours. 48.46 g (29.3 mmol) = 73.2% of the theory of bisanilide are obtained as crystals. Mp .:&gt; 350 ° C

c) Benzyloxy-malonic acid bis [3- (2,3-diacetoxy-N-methyl-propylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo-N-methyl-anilide]

82.76 g (50 mmol) benzyloxy-malonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) -N-methyl-anilide] are dissolved in 830 ml acetone, 18 , 6 g (65 mmol) Na₂CO₃ x 10 H₂O, 6.3 g (60 mmol) N-methylamino-propanediol-2,3 added and boiled under reflux for 2 hours. The implementation is then complete. It is cooled to room temperature, the solid precipitate is filtered off with suction, the filtrate is concentrated in vacuo to give the oil, this is dissolved in 300 ml of dioxane, residual water is removed by azeotropic distillation, the dioxane used is replaced again, 36.75 g (360 mmol) of acetic anhydride and 0.61 g (5 mmol) of 4-dimethylamino-pyridine were added and the mixture was stirred at 80 ° C. for 3 hours. The solvent is distilled off in vacuo, the oily residue is dissolved in ethyl acetate and chromatographed on 850 g of silica gel 60 using hexane / ethyl acetate 1: 1. The corresponding fractions are combined and evaporated to a solid foam in vacuo. The yield is 77.1 g (39 mmol) = 78% of theory.

d) Hydroxymalonic acid bis [(2,3-dihydroxy-N-methylpropylcarbamoyl-5- (2,3-dihydroxypropylcarbamoyl) -2,4,6-triiodo-N-methylanilide]

39.5 g (20 mmol) benzyloxy-malonic acid bis [3- (2,3-diacetoxy-N-methyl-propylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo- N-methyl-anilide] are dissolved in 200 ml of absolute ethanol and a total of 1.38 g (60 mmol) of sodium are added in small portions. The solution is stirred at room temperature for 12 hours. The reaction solution is then concentrated in vacuo to approximately half, mixed with 100 ml of water and with conc. NaOH saponified at 50 ° C at pH 10-12. After saponification is complete with conc. Neutralized hydrochloric acid, evaporated in vacuo to the oil, dissolved this in 100 ml of water and desalinated the solution on ion exchangers. The eluate is evaporated to the foam in vacuo and this is dried in vacuo at 50 ° C. for 24 hours. The yield is 23.25 g (15 mmol) = 75% of theory.

EXAMPLE 13

Hydroxymalonic acid bis [3- (2,3-dihydroxy-N-methyl-propylcarbamoyl-5- (2,3-dihydroxy-propylcarbamoyl) -2,4,6-triiodo-N-methylanilide]

a) Bromomalonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) -N-methyl-anilide]

37.42 g (50 mmol) of 5-methylamino-2,4,6-triiodoisophthalic acid (2,3-diacetoxypropyl) monoamide chloride are suspended in 370 ml of toluene and the suspension is heated to 100.degree. A clear solution is created. 5.5 g (25 mmol) of bromalonic acid dichloride (calc.<u style="single">1908</u>, 4465) added. After a few minutes, the bisanilide precipitates out as a crystalline precipitate. After 30 minutes, the heating is removed, the mixture is cooled to room temperature, the precipitate is filtered off with suction and dried at 50 ° C. in vacuo for 24 hours. 31.32 g (19.05 mmol) = 76.2% of the theory of bisanilide are obtained as crystals. Mp .:&gt; 350 ° C

b) Bromomalonic acid bis [3- (2,3-diacetoxy-N-methyl-propylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo-N-methyl-anilide]

24.66 g (15 mmol) bromalonic acid bis [3-chlorocarbonyl-2,4,6-triiodo-5- (2,3-diacetoxypropylcarbamoyl) -N-methyl-anilide] are dissolved in 250 ml acetone, 5 , 58 g (19.5 mmol) Na₂CO₃ x H₂O, 1.89 g (18 mmol) N-methylamino-propanediol-2,3 added and boiled under reflux for 2 hours. It is cooled to room temperature, the solid precipitate is filtered off with suction and the filtrate is concentrated to an oil in vacuo. The oil is dissolved in 200 ml of dioxane, residual water is removed by azeotropic distillation and the dioxane used is replaced again. 11.02 g (108 mmol) of acetic anhydride and 0.183 g (1.5 mmol) of 4-dimethylamino-pyridine are added, and the mixture is stirred at 80 ° C. for 3 hours. The solvent is distilled off in vacuo, the oily residue is dissolved in ethyl acetate and chromatographed on 500 g of silica gel 60 with hexane / ethyl acetate 1: 1. The corresponding fractions are combined and evaporated to a solid foam in vacuo. The yield is 20.94 g (10.74 mmol) = 71.6% of theory.

c) Hydroxymalonic acid bis [3- (2,3-dihydroxy-N-methyl-propylcarbamoyl) -5- (2,3-dia-hydroxypropylcarbamoyl) -2,4,6-triiodo-N-methylanilide]

19.5 g (10 mmol) bromomalonic acid bis [3- (2,3-diacetoxy-N-methyl-propylcarbamoyl) -5- (2,3-diacetoxypropylcarbamoyl) -2,4,6-triiodo-N- methyl anilide] are dissolved in 50 ml of DMF, 4.91 g (50 mmol) of potassium acetate are added and the solution is stirred at 50 ° C. for 12 hours. The reaction solution is then poured into 500 ml of water, the intermediate peracetate precipitating as an amorphous precipitate. This precipitate is filtered off, washed with water, suspended in 100 ml of water and concentrated. NaOH saponified at pH 10-12 and 50 ° C. When the hydrolysis has ended, the mixture is neutralized with hydrochloric acid and desalted using ion exchangers. The aqueous eluate is evaporated to dryness. The yield is 11.32 g (7.3 mmol) = 73% of theory.