NO822907L - Bromine-containing benzene derivatives and roentgen contrast agents containing such derivatives - Google Patents

Description

The present invention relates to a compound with an iodobenzene structure suitable as an X-ray contrast medium,

with a greater tolerance than analogue polyiod-

compounds and an opacity of the same order of magnitude as the polyiodine compounds and the peculiarity of the compounds according to the invention is that parts of the nuclear iodine atoms present in the analogous polyiodine compounds are replaced by bromine atoms.

The invention also relates to X-ray contrast material and

the peculiarity of the X-ray contrast material according to the invention is that it contains at least one compound as defined above.

These and other features of the invention appear in the patent claims.

Iodobenzene compounds with several iodine atoms in the benzene nucleus, usually three iodine atoms per benzene core, and various other substituents have long been used as X-ray contrast media. They mentioned other substituents

are pharmacologically tolerable groups that allow delivery

of the connections between humans and animals. Such substituents are generally chosen to give the compounds sufficient water solubility to allow the supply of said compounds as aqueous solutions.

Several methods have previously been proposed to increase the tolerance of the iodobenzene compounds used as X-ray contrast media.

A first type of methods involved the synthesis of structures with two or three triiodobenzene cores, see e.g. US Patent No. 3,290,366 and British Patent No. 1,346,795.

Another type of methods involved the selection of :substituents other than iodine atoms to achieve an improved tolerance. More particularly, this type of method involved non-ionic structures, i.e. which did not exhibit any ionizing substituents such as carboxy groups,

see e.g. German Patent Document No. 2,031,724 and French Patent Document No. 2,253,509.

A fourth type of methods involved the synthesis of dissymmetric polyiodo-di- or tri-benzene compounds with a single ionizing group, see e.g. US Patent No. 4,014,986.

By the works that underlie it

present invention, one has sought to solve the problem of increasing the tolerance of iodobenzene compounds in a way that is fundamentally different from previous work based on the realization, contrary to what one might expect, that when parts of the nuclear iodine atoms in iodobenzene compounds is replaced by bromine atoms, not only is the tolerance of the compounds increased, but the resulting opacity is also of the same order of magnitude.

This last relationship is particularly surprising because it would normally be expected that replacement of iodine atoms with bromine atoms would lead to a significant reduction in opacity. It is known that the opacity of an atom to X-rays is mainly proportional to the third power of its atomic number, see J. Duheix,

V. Bismuth, M. Laval-Jeantet, Traité de Radiodiagnostic, Volume 1 - L'image radiologique, Masson & Cie., 1969. The atomic number of bromine is 35 while the atomic number of iodine is 53. Therefore the opacity imparted by bromine should be three

or four times lower. One should thus expect that replacing part of the iodine atoms with bromine atoms would lead to a significant reduction in opacity,

to the point where the compound would no longer be practically useful as an X-ray contrast material. IN

.contrary to this, by partial replacement of the iodine atoms with i

bromine atoms, it is possible to obtain opacities which are of the same order of magnitude as those obtained with the corresponding polyiodine compounds. This entails a significant further economic advantage in that bromine is currently cheaper than iodine.

In the compounds in question, the number of nuclear bromine atoms advantageously represents 1/2 - 2/1 of the number of nuclear iodine atoms. Preferably, the number of bromine atoms is equal to the number of iodine atoms in these compounds. In this case, these can typically be compounds with two benzene nuclei, one of which is a triiodo nucleus and the other a tribromo nucleus.

The compounds in accordance with the invention can typically be the following compounds:

I - Compounds with formula:

wherein X^, X2 and X^ are selected from I and Br as I and Br are present at the same time, and

Q^, Q2 and CU are pharmacologically tolerable groups.

in

II - Compounds with formula:

in which

Xl'X2'X3'X4'X5and X6 are v31*?1 from 1 0<3 Br idet

I and Br are present at the same time, and

Q-^, Q2'<Q>3/Q4/Y1, Y2 and P are pharmacologically tolerable groups.

Among compounds of formula (II), a particularly advantageous class is that which includes compounds with

formula (II )

cl

wherein Q^,<Q>2,<Q>2, Q^, Y^, Y2 and P are pharmacologically tolerable groups.

III - Compounds with formula

in which

X,, X„, X^, X., Xc, X,, X-, X0 are selected from I and Br as

1 z 3 4 D o / o

I and Br are present at the same time, and

Ql'Q2'Q3'Q4'Q5'Yl'Y2'Y3'Y4'Pl°g P2 are pharmacologically tolerable groups.

IV - Compounds with formula:

in which:

XlfX2, X3, X4, X5, X , X7, Xg, Xg are selected from I and Br as I and Br are present at the same time,

and Q1, Q2, Q3, Q4, Q5, Qg/Y2, Y3 and P are pharmacologically tolerable groups.

Examples of groups of the type Q, Y, Z and P are given below.

1) Q-type groups

a) hydrogen

b) hydrophilic amino groups such as:

. A group with formula:

in which:

m = 0, 1 or 2

n = 0 to 6

and the radicals R 1 , R 2 , R 2' and R 2 " are groups of formula

- sugar residues.

Typical examples of such groups include groups with formula

v

IN

where n = 0 - 3 and

A is a nitrogen-containing group such as defined above.

. groups with formula:

where n = 0 - 3

. groups with formula:

wherein Z = H or.OH

T = H or OH

x = 0-3

c) ether or ester groups such as:

• C 1-5 alkoxy groups optionally substituted

with carbon groups or amino groups such as the A group defined above;

. groups with formula:

in

where m = 0 - 6

n = 0 - 6

a = 0 - 6

Z±= H, OH or NH2

T1= H, OH or NH2

. groups of formula -0-C - Ar

0

wherein Ar represents an aromatic radical

. groups with formula:

wherein A has the above meaning.

d) sulfonyl groups such as e.g.

. the group -SO^H

. groups of formula -SO2~A

wherein A has the above meaning.

e) groups with a carbon bond such as e.g.

. groups of formula -(CHZ) T

a

where a = 0 - 6

Z = H or OH

T = H or OH

. groups of formula -(CH2)n-0-Ar in which Ar represents an aromatic radical

>

in

. groups with formula

where n = 0 - 6

A has the above meaning

where a = 0 - 6 Z = H or OH T = H or OH

where a = 0 - 3

Z = H or OH

T = H or OH

. the group -C = N

2) Y-type groups (bivalent)

a) groups with a carbon bond such as e.g. . groups with formula in which a, b = 0 - 6 Z = H or OH T = H or OH . the group. groups with formula

in which a = 0 - 6 Z = H or OH T = H or OH b) other types of groups such as: . groups with formula

where n- = 1 - 6

. the oxy group - 0 - . groups with formula

where a = 0 - 3

Z, T = H or OH

. groups with formula

where a/ b = 0 - 3

Z, T = H or OH

3) Type P groups

Divalent P groups can be represented by the general formula

in which:

d, e, h, j = 0, 1 or 2

a, f, g, i = 0 - 6

Z, U, B, V = H, OH, Br, (CH„) COOH where n= 0-3

z n

T, D = H or OH

Other remains may be embedded in the bridge, such as e.g. groups with formula -0-, -S-,

Trivalent P groups can be groups with formula:

A preferred group of compounds in accordance with the invention are compounds with the formula:

in which:

X^, X2 and X^ represent Br or I, at least one of which is different from the other two, Q 1 is a group -COOH or a group of formula

in which R~and R . independently of each other is a hydrogen atom, a lower alkyl group, a mono- or polyhydroxy lower alkyl group or a carboxy lower alkyl radical, Q 2 represents a hydrogen atom, a CH 2 OH radical, a cyano radical, a radical of formula in which R,, and R^ independently of each other are a hydrogen atom, lower alkyl, mono- or polyhydroxy lower alkyl, or a lower alkanoyloxy-lower-alkyl radical an amino group, or a radical of formula in which R is lower- alkyl,

lower hydroxyalkyl or lower-alkoxy-lower-alkyl1, and Rg is a hydrogen atom, lower-alkyl or lower-hydroxyalkyl,

IN

Q- and 'independently represent et

hydrogen atom, a cyano radical, a CB^OH radical, et

radical with formula

wherein R and R1A have the same meanings as shown for R^ and R^, an amino group or a radical of formula -N-COR^ wherein R^ R12 has the same meaning as given for R^ and R^2 has the same meaning as given for Rg, Q. represents an amino group, a cyano radical or a group of formula

wherein R^c- is lower-alkyl, mono- or poly-hydroxy-lower-alkyl or lower-alkoxy-lower-alkyl, and R^g is a hydrogen atom, lower-alkyl, lower-hydroxyalkyl or lower-alkanoyl,

Z = H or OH

n^ and n2= 1 - 5

n^= 0 - 3, and

b = 0 or 1,

and their pharmaceutically acceptable salts.

In the present context, the term "lower" generally refers to radicals with 1-6 carbon atoms.

For the preparation of the compounds of formula (V), the method referred to in US Patent No. 4,014,986 can be used, which comprises the condensation of an amine of formula (VI). with an acid chloride of formula:

typically in a polar solvent at a temperature of 10-60°C in the presence of an acid-binding agent.

More generally, the compounds according to the invention can be prepared according to methods used for the preparation of the polyiodine analogues. For this purpose, typical useful reactions include halogenation, alkylation, acylation (by condensation of an acid chloride with an amine or an alcohol) or salt formation reactions, reactions which have been described in detail for the polyiodine analogues.

Thus, e.g. the compounds with the general formula

in which:

is Br and X^ is I or X-^ is I and X^ is Br, Q1 and Q. independently represent a

amino radical or a radical with the formula -N-COR,oi ly<R>20

wherein R^g represents lower-alkyl, mono- or poly-hydroxy-lower-alkyl, or lower-alkoxy-lower-alkyl and R2q represents a hydrogen atom, lower-alkyl or lower-hydroxyalkyl,

Q2 and independently represent a hydrogen atom, a CH2OH radical, a radical of formula

wherein R^ and R^ are independently a hydrogen atom, lower alkyl, mono- or polyhydroxy-lower alkyl, or lower alkanoyloxy-lower alkyl, an amino group or a radical of formula wherein R^ is lower-alkyl, mono- or poly-hydroxy-lower-alkyl or lower alkoxy-lower-alkyl, and Rg is a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, and R^7 and R^g independently represent a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, °g n is an integer from 1 to 5, is prepared by condensation of an amine of formula with an acid chloride of formula:

where the reaction is possibly followed by an acylation reaction.

The working conditions may be as described in French patent document no. 2,313,018.

Similarly, compounds with the formula:

in which:

is Br and X2 is I or X^ is I and X^ is Br, represents a COOH group, Q2 represents a hydrogen atom, a CH^OH radical, a radical with formula

in which Rcog R& independently of each other is a hydrogen atom, lower-alkyl, mono- or poly-hydroxy-lower-alkyl, lower-alkanoyloxy-lower-alkyl, an amino group or a radical with formula

wherein R^ is lower-alkyl, lower-hydroxy- alkyl or lower-alkyl-lower-alkyl and Rg is a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, Q represents a radical of formula

wherein R^ is as defined for R^ and R^2 is as defined for Rg,

R 2 ^ represents a hydrogen atom, lower alkyl or lower hydroxyalkyl, and,

IN

n is an integer from 1 to 5,

and their pharmaceutically acceptable salts, are prepared by condensation of an amine of formula

with an acid dichloride of formula:

the reaction possibly being followed by an acylation and/or salt formation reaction.

The working conditions may be as described in French patent application no. 2,347,339.

Examples of the preparation of the compounds in accordance with the invention are given below.

In these examples, the products were characterized by their Rf value by thin-layer chromatography (TLC) over a silica gel plate, using the following eluents: - Eluent 1: Benzene/methyl ethyl ketone/formic acid

(60:25:20)

- Eluent 2: n-butanol/acetic acid/water (50:11:25).

IN

EXAMPLE 1

Preparation of 2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-(2,4,6-triiodo-3-N-methylcarbamoyl-5-N-methyl-N-acetyl-amino-benzoyl)-glycylamino- benzoic acid

(compound 1)

I - Preparation of 2, 4, 6-tribromo-3-N-hydroxyethyl-carbamoyl-5-amino-benzoic acid 1 mol of 3-N-hydroxyethylcarbamoyl-5-amino-benzoic acid is suspended in water (4 liters) and concentrated hydrochloric acid (820 ml), bromine (230 ml; 9 mol) is added dropwise thereto. Stirring is continued for 24 hours at room temperature. The reaction mixture is thus sucked off on a filter, the precipitate washed with water (2 litres) at 90°C and then dried at 110°C for 24 hours.

Yield: 96.5%.

Purity control:

TLC in eluent benzene/methyl ethyl ketone (MEK)/formic acid (60:25:20)

. Rf of starting material: 0.06

. Rf of the bromine compound: 0.55

Purity by bromine titration: 100%.

in

II - Preparation of 2, 4, 6- tribromo- 3- N- hydroxyethylcarbamoyl- 5- aminoacetamido- benzoic acid

a) Preparation of 2,4,6-tribromo-3-N-phthalimido-acetoxyethylcarbamoyl-5-phthalimidoacetylamino-benzoic acid

2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-amino-benzoic acid (322 g; 0.7 mol) is dissolved in dimethylacetamide (600 ml). Phthalyl glycine chloride (392 g; 1.75 mol) is added portionwise thereto. After stirring for 48 hours at room temperature, the solution is poured over 2 liters of water at 70°C. A precipitate forms. Stirring is continued for a further 1/2 hour, after which the material is suctioned onto a filter.

The product is used without drying and without further cleaning in the subsequent step.

Control:

TLC in benzene/MEK/formic acid eluent (60:25:20):

. Rf 0.7 (Rf of starting material: 0.55).

b) Preparation of 2,4,6-tribromo-3-N-hydroxyethyl-carbamoyl-1-5-aminoacetamido-benzoic acid

The previously obtained product is suspended in 2.4 liters of water and 204 ml of hydrazine hydrate. The material is first heated at 90°C for 1 hour, after which stirring is continued for a further 48 hours at room temperature. Crystallization takes place. The resulting material is then filtered off and purified with water to give a product containing 10-15% phthalhydrazide. The product is taken up in 1 liter of water and 100 ml of concentrated sulfuric acid and the mixture is heated to 90°C. Insoluble substance is filtered off and the pH is adjusted to 3-4 with ammonia. Crystallization is allowed to take place overnight at room temperature.

The resulting material is filtered off, washed with water and dried in an oven to give 175 g of product, i.e. a yield of 48.5%.

Purity control:

1 - TLC in benzene/MEK/formic acid 60:25:20 eluent: Rf = 0.05 (orange-yellow spot when developing with

ninhydrin).

This leaves 1% phthalhydrazide with Rf 0.75.

2 - Purity by iodine titration: 98%.

III - Preparation of 2, 4, 6- tribromo- 3- N- hydroxyethyl-carbamoyl- 5-( 2- 4- 6- tri 1 od- 3- N- methylcarbamoyl- 5-N- methyl- N- acetylamino- benzoyl )- glycylamino-benzoic acid a) Condensation.

2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-amino-acetamido-benzoic acid (75 g; 0.145 mol) is slurried in a mixture of dimethylacetamide (75 mL) and triethylamine (56 mL; 0.4 mol). 4,4,6-triiodo-3-N-methylcarbamoyl-5-N-methyl-N-acetylaminobenzoic acid chloride (103 g; 0.159 mol) is then added thereto. The mixture is stirred at 45°C for 3 hours. Completion of the reaction is monitored using TLC.

The resulting solution is poured over 500 ml of water

and 40 ml of concentrated hydrochloric acid. A precipitate forms and the reaction mixture is stirred at room temperature for .15 hours. After suction on a filter, the product is taken up in 300 ml of water, dissolved by the addition of 5N sodium hydroxide (pH 7.8) and then precipitated again with 5N hydrochloric acid. The material is then filtered off, washed with water and dried in an oven at 60°C to give 114.5 g of crude product with a yield of 80%.

b) Purification.

Purification can be carried out by crystallization from hot

absolute ethanol.

114 g are suspended in 125 ml of absolute ethanol. The material is then boiled under reflux. The material dissolves, followed by crystallization. Heating is maintained for 24 hours. After cooling, the product is sucked off on a filter, dried and dissolved in 250 ml of aqueous sodium hydroxide.

The pH is adjusted to 4-5 with acetic acid and the product is treated twice with charcoal 3SA. It is then filtered and acidified with concentrated hydrochloric acid.

After suction on the filter, washing with water and drying

in an oven at 60°C, 54.5 g of pure product is obtained (yield: 47.5%).

Purity control:

1) TLC

- in eluent benzene/MEK/formic acid 60:25:20

Rf 0.15

- in eluent butanol/acetic acid/water 50:11:25 Rf 0.3 and 0.38

2).Purity by titration with sodium methoxide: 97%

3) Purity by iodine titration: 100%, by bromine titration: 100%.

EXAMPLE 2

Preparation of 2,4,6-triiodo-3-N-hydroxyethylcarbamoyl-5-(2,4,6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylamino-benzoyl)-glycylamino-benzoic acid ( compound 2)

I - Preparation of 2,4,6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid 1) Preparation of 2,4,6-tribromo-3-N-methylcarbamoyl-5-amino -benzoic acid

3-N-methylcarbamoyl-5-amino-benzoic acid (194 g; 1 mol) is suspended in water (4 liters) and concentrated hydrochloric acid (820 ml). Bromine (230 ml; 9 mol) is added dropwise thereto. Stirring is continued for 2-4 hours at room temperature. The resulting material is filtered off, the precipitate is washed in 2 liters of water at 90°C and then dried for 24 hours at 110°C to give 410 g of crude acid (Yield: 95%).

Purity control:

TLC in eluent benzene/MEK/formic acid (60:25:20)

. Rf starting material: 0.1

. Rf bromine product: 0.7

Purity by bromine titration: 98%.

2) Preparation of 2,4,6-tribromo-3-N-methylcarbamoyl-5-N-acetylamino-benzoic acid

a) Condensation

2,4,6-tribromo-3-N-methylcarbamoyl-5-amino-benzoic acid

(230g; 0.5 mol) is suspended in acetic anhydride (200 ml) and acetic acid (100 ml). Concentrated sulfuric acid (60 ml) is added dropwise to it (the temperature should not exceed 50-60°C). When the addition of sulfuric acid is complete, the reaction mixture is stirred for 1 hour at 55°C. The resulting solution is poured over a mixture of 1 liter of water + ice. Precipitation takes place. The material is filtered off, washed with water and dried in an oven for 16 hours at 80°C to give 240 g of crude acid (yield: 100%).

b) Purification

Purification is carried out by•crystallization of ammonium salt.

42 g of raw acid is suspended in 45 ml of water. 10 N aqueous ammonia is added until complete dissolution (ie pH 7-8). The solution is stirred for 24 hours at room temperature. Crystallization takes place. After suction on a filter and cleaning with 10 ml of water, the precipitate is dissolved in 500 ml of water at 90°C. Two treatments with charcoal 3SA are carried out for 2 hours at 80°C, after which the product is precipitated with 1/10 hydrochloric acid, filtered off with suction, washed with water and dried overnight at 80°C to give 30 g of the desired product (yield: 71 %).

Purity control:

- TLC

- in eluent benzene/MEK/formic acid (60:25:20)

. RF of starting material: 0.7

. RF of acetylated product: 0.35

- in eluent butanol/acetic acid/water (60:11:25)

. RF of starting material: 0.75

. Rf of acetylated product: 0.3

- Purity by bromine titration: 100%

- Purity by titration with sodium hydroxide: 99%.

3) Preparation of 2,4,6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid

2,4,6-tribromo-3-N-methylcarbamoyl-5-N-acetylaminobenzoic acid (189 g; 0.4 mol) is dissolved in 184 ml of 5N sodium hydroxide (0.92 mol). Methyl iodide (32.4 ml; 0.52 mol) is added thereto and the mixture is stirred for 24 hours at room temperature. Completed reaction is checked by means of TLC in eluent. butanol/acetic acid/water 50:11:25. The solution is poured over water (300 ml) and concentrated hydrochloric acid (75 ml). Precipitation takes place. The material is allowed to crystallize for 5 hours and is then suctioned off on a filter. The precipitate is taken up in 500 ml of water. 10N sodium hydroxide is added until complete

IN

solution, after which the pH is adjusted to 4 by adding acetic acid. 1 ml of sodium bisulphite solution is added to decolorize the solution. The material is precipitated in an acidic medium, filtered off with suction, washed with water and dried for 24 hours at 80°C to give 157 g of the desired product (yield: 81% for the methylation).

b) Purification

Purification is carried out by recrystallization from ethanol-water.

100 g of raw acid is suspended in 500 ml of water. The suspension is heated at 80°C and 95% ethanol (130 ml) is added slowly until complete dissolution. The material is sucked off on a filter and allowed to recrystallize with stirring for 24 hours. It is extracted on a filter, cleaned with water-ethanol and dried

in an oven for 24 hours at 80°C to give 62.8 g of product which is dissolved in 200 ml of water and sodium hydroxide.

The pH is adjusted to 4-5 with acetic acid. After two charcoal treatments, the material is filtered off, acidified with concentrated hydrochloric acid, after which it is filtered off, washed with water and dried at 80°C for 24 hours to give 5 g of pure product (with a yield of 50%).

Purity control:

- TLC in eluent butanol/acetic acid/water 50:11:25

. RF of starting material : 0.3

. Rf of methylated product: 0.25 and 0.35

- Purity by titration with sodium methoxide: 97%

- Purity by bromine titration: 97%.

II - Preparation of 2, 4, 6- tribromo- 3- N- methylcarbamoyl-5- N- methyl- N- acetylamino- benzoic acid chloride

2,4,6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid (296 g; 0.59 mol) is slurried in thionyl chloride (600 ml). The mixture is heated at 80°C for 3 hours with stirring to give a solution. Excess thionyl chloride is evaporated under vacuum. The paste-like residue is taken up in 500 ml of isopropyl ether and stirred at room temperature for 24 hours. Crystallization takes place. After suction on a filter and clarification with isopropyl ether, the precipitate is washed in 250 ml of acetone for 24 hours at room temperature, with stirring, after which it is suction on a filter, clarified with 50 ml of acetone and dried to give 150 g of light beige colored product (yield: 50.5%).

Purity control:

1) TLC (after reaction with an excess of monoethanolamine in dimethylacetamide) in eluent: benzene/MEK/formic acid 60:25:20

. Rf of starting material: 0.57

. Rf of monoethanolamine condensation product: 0.35

2) Determination of the acid chloride with propylamine: 105%.

III - Preparation of 2, 4, 6- triiodo- 3- N- hydroxyethyl-carbamoyl- 5-( 2- 4- 6- tribromo- 3- N- methylcarbamoyl1-5- N- methyl- N- acetylamino- benzoyl)- glycylamino-benzoic acid

2,4,6-triiodo-3-N-hydroxyethylcarbamoyl-5-(2-4-6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylaminobenzoyl)-glycylamino-benzoic acid is prepared as in example l - III

from 2,4,6-triiod-3-N-hydroxyethylcarbamoyl-5-amino-acetamido-benzoic acid and 2)4,6-tribromo-3-N-methylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid chloride.

Raw product yield: 55%. Total dividend: 21%.

Purity control:

1) TLC

. in eluent benzene/MEK/formic acid 60:25:20

Rf 0.3

. in eluent butanol/acetic acid/water 50:11:25 Rf 0.2-0.3.

2) Purity by titration with sodium methoxide: 99.6%

3) Purity by iodine titration: 98.3%

by bromine titration: 99.4%.

EXAMPLE 3

Preparation of 2, 4, 6- tribromo- 3- N- hydroxyethylcarbamoyl-5-( 2, 4, 6- triiodo- 3- N- hydroxyethylcarbamoyl- 5- N- methyl- N- acetylamino- benzoyl)- glycylamino- benzoic acid

(Compound 3)

I) Preparation of 2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid

2,4,6-triiodo-3-N-hydroxyethylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid (900 g; 1.38 mol) is slurried in dioxane (1500 ml). Acetyl chloride (198 ml) is added l

drop by drop there. A clear solution is obtained after heating for 4 hours at 80°C. After cooling, this solution is poured over 4.5 liters of isopropyl ether. The resulting white crystals are filtered off, washed with water and dried in an oven at 70°C.

Yield: approximately 100%.

TLC in eluent #1: Rf 0.45.

II) Preparation of 2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-N-methyl-N-acetylamino-benzoic acid chloride

960 g of the preceding acid are refluxed for 6 hours in 280 ml of thionyl chloride. The acid chloride crystallized from the thionyl chloride is sucked off on the filter after cooling and washed with isopropyl ether.

Yield: 55%.

- Organic chlorine determination: 101%

- TLC in eluent no. 1: Rf 0.6 after condensation

with propylamine.

III) Condensation

2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-(2-4-6-triiodo-3-N-acetoxyethylcarbamoyl-5-N-methyl-N-acetylamino-benzoyl)-glycylamino-benzoic acid of formula

is prepared by the method in example 1 from 2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-amino-acetamido-benzoic acid and 2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-N-methyl-N -acetylaminobenzoic acid chloride.

Condensation yield: 70%.

Purity control by TLC in eluent no. 1: Rf 0.1.

IV) Saponification

The preceding product is dissolved in 2N sodium hydroxide (320 ml). The solution is heated at 50°C for 2 hours, after which the product is precipitated with hydrochloric acid, filtered off with suction, washed with water and dried in an oven at 70°C.

Yield: 65%.

V) Purification

Purification is carried out by crystallization of the methylamine salt from ethanol. The purified product is sucked off the filter and then washed with propanol at 80°C for 2 hours.

The methylamine salt is then dissolved in sodium hydroxide after which it is decoloured by treatment with charcoal 3SA at pH 5 for 3 hours at 60°C.

The purified product is sucked off on a filter, washed repeatedly with water until there is an absence of chloride and traces of methylamine.

Purity control:

1) TLC:

- in eluent 1 Rf 0.1

- in eluent 2 Rf 0.25 and 0.3.

2) Purity by iodine titration: 97%

3) Purity by bromine titration: 96%.

EXAMPLE 4

Preparation of 2, 4, 6- tribromo- 3- N- hydroxyethylcarbamoyl-5- ( 2, 4, 6- tri in od- 3- N- hydroxyethylcarbamoyl- 5- N- acetylamino- benzoyl)- glycyl- N- methylamino- benzoic acid (Compound 4)

I - Preparation of 2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-chloro-acetamido-benzoic acid

To a suspension of 2,4,6-tribromo-3-N-hydroxyethyl-carbamoyl-5-aminobenzoic acid (1 mol; 461 g) in dioxane (1 litre) is added dropwise 3 mol of chloroacetyl chloride.

The reaction mixture is heated for 3 hours at 80°C. The product is dissolved and then recrystallized. The product, converted to amide and esterified with chloroacetyl chloride, is filtered off with suction and washed with water. The ester function is then saponified with 2 mol of sodium carbonate in water at room temperature. The resulting product is then precipitated with hydrochloric acid, filtered off with suction and washed with water. Yield: 78%.

TLC: eluent #1: Rf 0.35

eluent #2: Rf 0.5

Cl % found: 6.55 Cl % theoretical: 6.60

;Br % found: 44.65 Br % theoretical: 44.65

in

II - Preparation of 2,4,6-tribromo-3-N-hydroxyethyl-carbamoyl-5-iodo-N-methyl-acetamido-benzoic acid

The preceding acid (0.75 mol) is dissolved in 5N sodium hydroxide (2.23 mol) and CH 3 I (1.5 mol). After heating at 40°C for 4 hours, the solution is poured into 400 ml of industrial HCl diluted to 1/2 with ice-cold water. The resulting pale yellow precipitate is filtered off with suction and washed with water.

Yield: 85%.

Acidity determination: 97.8%

Iodine titration: 1% found: 19.35 1% theoretical: 19.75 Bromine titration: Br% found: 36.55 Br% theoretical: 37.3 TLC: eluent #1: Rf 0.4.

III - Preparation of 2,4,6-tribromo-3-N-hydroxyethyl-carbamoyl-5-amino-N-methyl-acetamido-benzoic acid.

The preceding product (0.517 mol) is heated for 2 hours at 60°C in 1.5 liters of 10N ammonia solution.

Ammonia is then evaporated under vacuum from a water pump to give 350 g of an equimolar mixture of the ammonium salt of the desired product and ammonium chloride.

IN

TLC, eluent #1: Rf = 0.05.

This product is used further without further purification.

IV - Condensation

2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-(2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-amino-benzoyl)-glycyl-N-methylamino-benzoic acid with formula:

is prepared from 2,4,6-tribromo-3-N-hydroxyethylcarbamoyl-5-amino-N-methylacetamido-benzoic acid and 2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-amino-benzoic acid chloride.

Condensation yield: 81%

TLC, eluent #1: Rf 0.1

This product is used further without further purification.

V - Acetylation

The preceding crude acid (357 g) is dissolved in dimethylacetamide (330 ml). Acetyl chloride (1.23 mol) is added dropwise thereto. The resulting solution is stirred for 4 hours at room temperature and then poured into water. The resulting precipitate is suctioned off on a filter and washed with water.

\

The product obtained in this way is further used as such without further purification or drying.

VI - Saponification of the ester functions.

The preceding crude acid is dissolved in 2N sodium hydroxide (1.23 mol). The resulting alkaline solution is stirred at room temperature for 2 hours and then adjusted to pH 5 with acetic acid and treated twice with charcoal 3SA at 70°C. The filtered, well decolorized solution is poured over a hydrochloric acid solution. The desired product falls out and is separated using suction on a filter and washed several times with water.

Yield: 53.5% for acetylation + saponification.

Purification over ammonium salts.

The product is purified using two successive ammonium salts and then washed with water to remove the chlorides and the NH^"<1>" ions.

Provisions: acidity: 101.50%

Bromine : Found: 20.4% theoretical: 20.7%

Iodine: Found: 32.5% theoretical: 32.9%

TLC, eluent #1: Rf 0.05

TLC, eluent #2: 2 isomers Rf 0.17 and 0.27.

EXAMPLE 5

Preparation of compound of the following formula

(Compound 25)

I - Condensation of diethanolamine with 2,4,6-tribromoamino-isophthalic acid dichloride leading to the compound of formula:

To a solution containing 1.18 mol of diethanolamine in 100 ml of water and 1.18 mol of KHCO 3 , 184 g (0.4 mol) of 2,4,6-tribromo-amino-isophthalic acid dichloride dissolved in 185 ml of acetone are added dropwise.

A white product gradually precipitates. By suction on a filter and drying in an oven, 278 g of crude product is separated which migrates with Rf 0.1 in -eluent no. 1 and which contains 9.7% KCl and 26% KHCC>3 according to determinations of bromine, chlorine and acidity.

Purification by crystallization from ethanol:

278 g of raw product is heated to boiling in 1 liter of absolute ethanol. 97 g of inorganic insoluble substance is removed by hot suction on a filter. The raw product crystallizes gradually. After 2 days, 110 g of a well crystallized white product is obtained by suction on a filter.

Purity control:

- 98% purity by bromine titration

0% acidity by titration with sodium methoxide

- No Cl~

- TLC in eluent no. 1: a single spot Rf 0.1.

- Yield: 46.5% for condensation + purification.

IN

II - Chloroacetylation leads to the compound of formula:

To a suspension of 85 g of the preceding amine (crystallized from ethanol) in 1-0 ml of dioxane is added dropwise chloroacetyl chloride (80 ml). After 1/4 hour, the solution is complete. After stirring overnight at room temperature, the solution is poured over 500 ml of ice-mixed water and gives a gummy substance. The supernatant solution is withdrawn and replaced twice with 500 ml of ice-cold water. This gives a white crystalline product.

TLC eluent #1: Rf 0.6.

III - Saponification of the ester functions leads to the compound of formula:

The preceding product is dissolved in 1.144 mol of 2N sodium hydroxide and the resulting solution is stirred for 3 hours at room temperature.

IN

It is made so acidic to pH 2 and the monochloroacetic acid that. was formed during the saponification, extracted with 3 x 250 ml of ethyl acetate to neutral pH in both phases, to give 95 g of a white crystalline solid by evaporation to dryness.

TLC: eluent #1: Rf 0.1

Titration of organic and Br Cl: 95%.

IV - Amination leads to the compound of formula:

Dissolve the 95 g of the preceding product in 600 ml

ION ammonia solution. The solution is heated at 60°C for 3 hours and then evaporated to dryness to give a whitish solid containing 1 ml of NH 2 Cl per mol.

- TLC eluent no. 1: Rf 0

- TLC eluent isopropanol/ethyl acetate/NH.OH (35:35:40) Rf 0.7

- TLC eluent no. 2: 2 spots Rf 0 and 0.1

These spots are developed with UV irradiation and ninhydrin.

V - Condensation

0.154 mol of the preceding product is condensed with 0.154 mol of 2,4,6-triiodo-3-N-methyl-methoxyacetamido-5-methylcarbamoyl-benzoic acid chloride in the presence of 0.23 mol of triethylamine, in DMAC at 45°C. DMAC will be so

continuously extracted with ethyl acetate and the nonionic I product extracted with phenol and the resulting aqueous solution evaporated.

Total dividend: 35%

TLC eluent #1: Rf 0.05;

eluent #2: Rf 0.3 and 0.45.

EXAMPLE 6

Preparation of the compound of formula:

(Compound 26)

I - Preparation of the compound of formula:

To a suspension of 80 g (0.60 mol) glycine ethyl ester hydrochloride in 500 ml anhydrous DMAC and 200 ml triethylamine, 176 g (0.39 mol) triiodo-5-amino-methylisophthalamic acid chloride is added in portions. After stirring by

room temperature, the reaction solution is poured over 2 liters of water. The resulting precipitate is suctioned off

filter, washed with water and dried to give 169 g of the desired product with a yield of 84%.

Purity (by bromine titration): 97%.

in

II - Preparation of the compound of formula:

155 g of ester (0.30 mol) are stirred at room temperature in 1 liter of 1N sodium hydroxide.

The acid is obtained by acidification with HCl. The resulting white crystals are filtered off and washed with water. Yield: 58.5%.

Purity (-COOH): 100.6%.

III - Preparation of the compound of formula:

12.2 g of the preceding product (0.025 mol) are dissolved in 40 ml of anhydrous DMAC and 6.7 ml of triethylamine. Phthalyl glycic acid chloride (9 g, 0.04 mol) is added portionwise with stirring. The reaction mixture is poured over water and the desired derivative crystallizes.

Yield: 50%.

Purity (bromine): 102.8%.

IV - Preparation of the compound of formula

24 g (0.03 mol) of the preceding product are heated in

50 ml of water and 5 ml of hydrazine hydrate for 8 hours at 70°C.

The resulting solid is filtered off and dried. Yield: 50%.

Purity (bromine): 99%.

V - Condensation

2.2 g (0.004 mol) of the previously obtained aminoacetylated acid are dissolved in 3 ml of DMAC + 1.4 ml of triethylamine + 1 ml of water; 2.7 g (0.004 mol) of 2,4,6-triiodo-5-methylacetamido-isophthalamic acid chloride are added portionwise thereto. After heating for 8 hours at 50°C, the material is precipitated in an acidic medium. The desired compound is collected after filtration and drying

(Yield: 61%).

TLC: eluent #2: Rf 0.65.

EXAMPLE 7

Preparation of 1, 2- N-( 2, 4, 6- triiodo- 3- N- hydroxyethyl-carbamoyl- 5- N- qluconyl- amino- benzoyl)- N'-( 2, 4, 6- tribromo-3- N-methylacetamido-5-N-gluconylamino-benzoyldiamino-ethane (Compound No. 28)

I - Preparation of (2,4,6-triiodo-3-N-acetoxyethyl-carbamoyl-5-amino)benzoylamino-ethylamine:

IN

2,4,6-triiodo-3-N-acetoxyethylcarbamoyl-5-aminobenzoic acid chloride (216 g, 0.325 mol) is suspended in 250 ml of water. Ethylenediamine (250 ml) is added with cooling to keep the temperature below 20°C. The solution is complete after stirring for 2 hours. Stirring is continued for a further 15 hours. The product crystallizes and is filtered off and washed with methanol to give 131 g of the desired product (Yield: 58.7%).

TLC (eluent 1): Rf 0.12.

II - Preparation of 2,4,6-tribromo-3-N-methylacetamido-5-amino-benzoic acid chloride. 20 g of the corresponding acid dissolved in 40 ml of SOC^ are heated at 80°C for 2 hours. After evaporation of the thionyl chloride, the oil is precipitated in 100 ml of isopropyl ether. The material is stirred for 1 hour, filtered off with suction, washed with ethyl acetate, filtered off with suction and dried to give 17 g of the desired compound (Yield: 81.5%).

TLC (eluent 1) Rf 0.75.

III - Preparation of 1,2-N-(2-4-6-triiodo-3-N-acetoxy-methylcarbamoyl-5-amino-benzoyl)-N'-(2,4,6-tribromo-3-N- methylacetamido-5-amino-benzoyl)-diamino-ethane

The compound obtained under I (100 g; 0.145 mol) is dissolved in 100 ml of DMAC in the presence of triethylamine (100 ml, to have basic pH). Powdered 2,4,6-tribromo-3-N-methylacetamido-5-amino-benzoic acid chloride (80 g; 0.168 mol)

IN

is added to the solution. The mixture is heated at 50°C for 7 hours and then stirred at room temperature for 8 hours. It is then treated with H20 (1 litre), filtered off with suction and dried to give 170 g of the desired compound

(Yield: 100%).

TLC (eluent #1) Rf 0.46.

IV - Preparation of 1,2-N-(2,4,6-triiodo-3-N-acetoxy-ethylcarbamoyl-5-N-penta-acetoxygluconylamino-benzoyl)-N'-2,4,6-tribromo-3 -N-methylacetamido-5-N-penta-acetoxygluconylamino-benzoyl)-diamino-ethane

The compound obtained in the preceding (100 g; 0.089 mol) is dissolved in 180 ml of DMAC. Powdered pentacetylated gluconic acid chloride (0.445 mol) is added thereto. The powder dissolves as it is added.

The mixture is stirred at room temperature for 20 hours and then added to 1.3 liters of ice-cold water. Stirring is continued overnight. After suction on the filter, the rubber-like material is taken up in 300 ml of CH2Cl2. The organic phase is washed with bicarbonate (5%) and then with H2O. It is evaporated to give 126 g of a beige colored product

(Yield: 75%)

V - Deprotection

Deprotection of the acetyl groups is carried out by transesterification using 100 g (0.053 mol) of the compound obtained in 250 ml of methanol in the presence of 6.2 ml (0.1 mol) of ethanolamine catalyst. After heating at 35°C for 48 hours and stirring at room temperature for 48 hours, the reaction mixture is made to flow through a resin H+. After evaporation of the filtrate, precipitation with H^O, 26.6 g of a still impure product are obtained. This dissolves in warm water. After removal of insoluble substance, the evaporated filtrate gives 4 g of the desired compound (Yield: 5.4%).

TLC: eluent 2 Rf of starting material 0.70; 0.86

Rf of product obtained 0.36; 0.40

eluent 1 Rf of starting material 0.72

Rf of product obtained 0.05

The properties of the compounds in Examples 1-7 are set out

in the subsequent tables I and II together with the properties for other compounds of the general formula (V) and for the compounds of formula (III) prepared by analogous methods.

Results of comparison tests carried out with compounds in accordance with the invention are given below.

1 - Opacity

The opacity was determined indirectly by means of the impression produced on photographic film by means of a beam of X-rays passing through a cell containing an aqueous solution of the compounds. The transparency of the film after development was determined using an optical densitometer. In each case, the determination was carried out with the same film and with the same X-ray source (70 kV) by comparison with a control contrast material.

The used comparison material "HEXABRIX" is a solution of sodium and methylglucamine salts of ioxaglinic acid containing 32% iodine.

The compounds of the invention were tested as aqueous solutions of their methylglucamine salts containing the same number of moles of compounds as

"HEXABRIX".

The results obtained are indicated in the following table III.

It appears from the previous results that the opacity

of the compounds according to the invention is very close to the opacity of "HEXABRIX" which is a single iodinated compound with a structure otherwise similar to the test compounds. To obtain products in accordance with the invention with the same opacity as that obtained with simply iodized products, it is only necessary to use

.1.09 times more moles of compound.

2 - Component activation

Work by Elliott C. Lasser (Investig. Radiol., 1974, 9, 4 6A) has shown that contrast media activate complement, which is a combination of serum proteins and whose activation can lead to severe anaphylactic reactions.

The determination of this activation is carried out by determining the 50% hemolytic concentration, denoted HCj-q. It is assumed that products with a less activating effect on complement, i.e. with a higher HC^q, cause less side effects of the anaphylactic type and thus exhibit an improved tolerance.

The results obtained are indicated in Table IV.

3 - Acute intracisternal toxicity

Acute intracisternal toxicity was determined in rats by the method of E. Melartin, P. Tuohimaa, R. Dabb. Investigative Radiology, 1970, Vol 5, No 1, 13-21.

The results obtained are given in the following table V.

From the foregoing, it can be concluded that the bromoiodine compounds according to the invention are indicated as X-ray contrast media.

The preferred delivery form consists of aqueous solutions of one or more of the bromoiodine compounds as defined above.

The aqueous solutions generally contain 5-100 g of bromoiodine compound and the injectable amount of these solutions can generally vary between 5 and 1,000 ml.

Claims (9)

1. Compounds with iodobenzene structure, suitable as X-ray contrast agents, with greater tolerance than analogous polyiodine compounds and an opacity of the same order of magnitude as polyiodine compounds, characterized in that part of the nuclear iodine atoms present in the analog polyiodine -compounds are replaced with bromine atoms. 2. Compounds as stated in claim 1, characterized in that the number of nuclear bromine atoms represents from 1/2 to 2/1 of the number of nuclear iodine atoms. 3. Compounds as stated in claim 2, characterized in that when two benzene nuclei are present, one is a triiodo nucleus and the other a tribromo nucleus. 4. Compounds as specified in claim 3, characterized in that they have the formula: 'wherein: Q^ / Cj2' 0.3/ Q4/ Y^ , Y^ and P are pharmacologically tolerable groups. 5. Compounds as specified in claim 1, characterized in that they have the formula: in which: X^ , X,,, X^ , X^ , X^ , Xg, X7 and Xg are selected from I and Br, I and Br being present at the same time, and Qr <Q2,><Q3,><Q>4 , Q5 , Yx , Y2 , Y3 , Y4< Pt and P2 are pharmacologically tolerable groups. 6. Compounds as stated in claim 1, characterized in that they have the formula: in which: X^ , X2 and X3 represent Br or I in that at least one of the groups is different from the other two, Q, is a group -COOH or a group of formula wherein R 3 and R 3 independently of each other are a hydrogen atom, lower alkyl, mono- or poly-hydroxy-lower alkyl i or a carboxy-lower alkyl, Q 2 represents a hydrogen atom, a CF^ OH radical, a cyano radical, a radical of formula in which Rj. and Rg independently of each other is a hydrogen atom, lower-alkyl, mono- or poly-hydroxy-lower-alkyl or lower-alkanoyloxy-lower-alkyl, an amino group, or a radical of the formula -N-COR- in which R- is In 7 7 8 lower-alkyl, lower-hydroxy-alkyl or lower-alkoxy-lower-alkyl and Rg is a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, Q_2 and Q^ ' independently represent a hydrogen atom, a cyano radical, a CH2 OH radical, a radical with formula wherein Rg and R^q have the same meaning as given for R^ and Rg, an amino group or a radical of formula in which R.^ has the same meaning as indicated for R^ and R^2 have the same meaning as stated for Rg, Q. represents an amino group, a cyano radical or a group with formula where R^cj is lower-alkyl, mono- or poly-hydroxy-lower-alkyl or lower-hydroxy-lower-alkyl and R.vg is a hydrogen atom, lower-alkyl, lower-hydroxyalkyl or lower-alkanoyl in Z = H or OH n 1 and n = 1 - 5 n 3 = 0 - 3, and b = 0 or 1, and their pharmaceutically acceptable salts. 7. Compounds as specified in claim 1, characterized in that they have the formula: in which: X^ is Br and X2 is I or X^ is I and X2 is Br, and independently represent an amino radical or a radical of formula in which R^ g represents a lower-alkyl, mono- or poly-hydroxy-lower-alkyl or lower-alkoxy-lower-alkyl and R2 q represents a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, Q2 and Q independently represent a hydrogen atom, a CH2 OH radical, a radical of formula wherein R,, and R^ are independently a hydrogen atom, lower alkyl, mono- or polyhydroxy-lower alkyl, or lower alkanoyloxy-lower alkyl, an amino group, ,or a radical with formula wherein R 1 is lower-alkyl, mono- or poly-hydroxy-lower-alkyl, or lower-hydroxy-lower-alkyl, and R 2 is a hydrogen atom, lower-alkyl, or lower-hydroxy-alkyl, and <R> 17 and R 17 independently represent a hydrogen atom, lower alkyl or lower hydroxyalkyl, and n is an integer from 1 to 5. 8. Compounds as stated in claim 1, characterized in that they have formula in which is Br and X^ is I or X^ is I and X^ is Br, Q 1 represents a COOH group, C>2 represents a hydrogen atom, a Cr^OH radical, a radical of formula wherein Rc and Rc are independently of each other a hydrogen atom, lower alkyl, mono- or polyhydroxy-lower alkyl, lower alkanoyloxy-lower alkyl, an amino group or a radical with formula wherein R 7 is lower alkyl, lower-hydroxyalkyl, or lower-alkoxy-lower-alkyl, and Rg is a hydrogen atom, lower-alkyl or lower-hydroxyalkyl, Q.. represents a radical of formula • I where R-Q is as defined for R and R is as defined for Rg, & 2i represents a hydrogen atom, lower-alkyl or lower-hydroxyalkyl and n is an integer from 1 to 5, and their pharmaceutically acceptable salts. 9. X-ray contrast material, characterized in that it comprises at least one compound as defined in claims 1-8, possibly in the form of an aqueous solution of the compound or compounds.