Contrast media may be administered in medical imaging procedures, for example X-ray, magnetic resonance and ultrasound imaging, to enhance the image contrast in images of a subject, generally a human or non-human animal body. The resulting enhanced contrast enables different organs, tissue types or body compartments to be more clearly observed or identified.

In X-ray imaging, the contrast media function by modifying the X-ray absorption characteristics of the body sites into which they distribute.

Clearly however the utility of a material as a contrast medium is governed largely by its diagnostic efficacy, by its toxicity, and any other adverse effects it may have on the subject to which it is administered, and by its ease of storage and ease of administration.

Since such media are conventionally used for diagnostic purposes rather than to achieve a direct therapeutic effect, when developing new contrast media there is a general desire to develop media having as little as possible an effect on the various biological mechanisms of the cells or the body as this will generally lead to lower animal toxicity and lower adverse clinical effects.

The toxicity and adverse biological effects of a contrast medium are contributed to by the components of the medium, e. g. the solvent or carrier as well as the contrast agent and its components (e. g. ions where it is ionic) and metabolites.

The following major contributing factors to contrast media toxicity and adverse effects have been identified:

-the chemotoxicity of the contrast agent, -the osmolarity of the contrast medium, and -the ionic composition (or lack thereof) of the contrast medium.

In coronary angiography, for example, injection into the circulatory system of contrast media has been associated with several serious effects on cardiac function. These effects are sufficiently severe as to place limitations on the use in angiography of certain contrast media.

In this procedure, for a short period of time a bolus of contrast medium rather than blood flows through the circulatory system and differences in the chemical and physicochemical nature of the contrast medium and the blood that it temporarily replaces can give rise to undesirable effects, e. g. arrhythmias, QT-prolongation, and, especially, reduction in cardiac contractile force and occurrence of ventricular fibrillation. There have been many investigations into these negative effects on cardiac function of infusion of contrast media into the circulatory system, e. g. during angiography, and means for reducing or eliminating these effects have been widely sought.

Early injectable ionic X-ray contrast agents, based on triiodophenylcarboxylate salts, were particularly associated with osmotoxic effects deriving from the hypertonicity of the contrast media injected.

This hypertonicity causes osmotic effects such as the draining out of water from red-blood cells, endothelial cells, and heart and blood vessel muscle cells. Loss of water makes red blood cells stiff and hypertonicity, chemotoxicity and non-optimal ionic make- up separately or together reduce the contractile force of the muscle cells and cause dilation of small blood vessels and a resultant decrease in blood pressure.

The osmotoxicity problem was addressed by the development of the non-ionic triiodophenyl monomers,

such as iohexol, which allowed the same contrast effective iodine concentrations to be attained with greatly reduced attendant osmotoxicity effects.

The drive towards reduced osmotoxicity led in due course to the development of the non-ionic bis (triiodophenyl) dimers, such as iodixanol, which reduce osmotoxicity associated problems still further allowing contrast effective iodine concentrations to be achieved with hypotonic solutions.

This ability to achieve contrast effective iodine concentrations without taking solution osmolality up to isotonic levels (about 300mOsm/kg H20) further enabled the contribution to toxicity of ionic imbalance to be addressed by the inclusion of various plasma cations, as discussed for example in WO-90/01194 and WO-91/13636 of Nycomed Imaging AS.

However X-ray contrast media, at commercial high iodine concentrations of about 300 mgI/mL have relatively high viscosities, ranging from about 15 to about 60 mPas at ambient temperature with the dimeric media generally being more viscous than the monomeric media. Such viscosities pose problems to the administrator of the contrast medium, requiring relatively large bore needles or high applied pressure, and are particularly pronounced in paediatric radiography and in radiographic techniques which require rapid, bolus administration, e. g. in angiography.

In practice, viscosities in excess of 30 mPas at body temperature (37°C) are unacceptably high for routine X-ray investigations, and especially for paediatric investigations. Accordingly, the maximum practical iodine concentration achievable with non-ionic iodinated X-ray contrast agents is generally about 300- 350 mgI/ml. Higher iodine concentrations, if accessible at acceptable viscosities, would increase the diagnostic efficacy of contrast enhanced images. Alternatively viewed, lower contrast medium viscosities for any given

iodine concentration would increase ease of administration and the range of investigations and patients for which the contrast media could be used.

Further iodinated contrast agents were described in WO 96/09282, also of Nycomed Imaging AS. These compounds show generally improved levels of viscosity over comparable non-ionic contrast agents. The low viscosity of these compounds was due, in particular, to the presence on the phenyl group of one or more C14 alkyl groups substituted by at least one hydroxyl group and optionally'linked to the phenyl ring via a carbonyl sulphone or sulphoxide group. The provision of iodinated non-ionic contrast agents having low viscosity has also been addressed in US patent No. 5,698,739 of Sovak. Here, triiodo 5-aminoisophthaldiamides are described wherein the amino and one of the amide nitrogens are substituted by alkyl or hydroxyalkyl groups; the compounds having at least two hydroxyl groups. There is, however, a continuing desire to produce contrast agents which enable delivery of a greater concentration of iodine without increasing viscosity, toxicity or osmolarity to unacceptable levels.

It has now been found that, surprisingly, a further group of compounds, the mandelic amides, combine low viscosity and high hydrophilicity.

Thus, viewed from one aspect, the present invention provides iodinated aryl compounds, useful as X-ray contrast agents of formula I wherein n is 0

or 1, preferably 0, and where n is 1 each C6R5 moiety may be the same or different; X denotes a bond or a group providing a 1 to 7, for example 1,2,3 or 4 atom chain linking two C6R5 moieties or, where n is 0, X denotes a group R; each group R is a hydrogen atom, an iodine atom or a hydrophilic moiety M or M1, two or three non- adjacent R groups in each C6R5 moiety being iodine and at least one, and preferably two, more preferably three, R groups in each C6R5 moiety being M or M1 moieties; each M which may be the same or different, preferably being different, is a non-ionic hydrophilic moiety; and each Mi independently represents a-CHOHCON (R1) 2 group wherein each R1, which may be the same or different, is a hydrogen atom, an OH group or a Cul-6 alkoxy or optionally hydroxylated ¬1-5 alkyi group, preferably a hydrogen atom, at least one R group in the whole molecule and where n = 1, preferably at least one R group in each C6R5 moiety, being an M1 moiety; and isomers thereof.

The low viscosity of the compounds of the invention is thought to derive from the a-hydroxyamide side chains. Compounds of the invention have advantageously low viscosities as compared to current commercially available products for use as X-ray contrast agents.

Low viscosity is a generally highly desirable property for X-ray contrast media, particularly so when the compounds are to be administered to children. The compounds of the invention will preferably have a viscosity of less than 20 more preferably less than 18, especially no more than 15 mPas in aqueous solution at 20°C and a concentration of 350 mgI/ml.

The compounds of the invention also exhibit an advantageously high hydrophilicity, and it is this combination of low viscosity and high hydrophilicity that makes the compounds of the invention so desirable for use in contrast media.

The solubilizing groups M may be any of the non- ionizing groups conventionally used to enhance water

solubility. Suitable groups include for example a straight chain or branched C1lO-alkyl group, preferably a C1-5 group, optionally with one or more CH2 or CH moieties replaced by oxygen or nitrogen atoms and optionally substituted by one or more groups selected from oxo, hydroxy, amino, carboxyl derivative, and oxo substituted sulphur and phosphorus atoms. Particular examples include polyhydroxyalkyl, hydroxyalkoxyalkyl and hydroxypolyalkoxyalkyl and such groups attached to the phenyl group via an amide linkage such as hydroxyalkylaminocarbonyl, N-alkyl- hydroxyalkylaminocarbonyl and bis- hydroxyalkylaminocarbonyl groups. Preferred among such groups are those containing 1,2,3,4,5 or 6, especially 1,2 or 3, hydroxy groups, e. g. <BR> <BR> <BR> <BR> <BR> <BR> <BR> <P>-CONH-CH2CH20H<BR> <BR> <BR> <BR> <BR> -CONH-CH2CHOHCH20H -CONH-CH (CH20H) 2 -CON (CH2CH20H) 2 as well as other groups such as -CONH2 <BR> <BR> <BR> <BR> -CONHCH3<BR> <BR> <BR> <BR> <BR> -OCOCH3<BR> <BR> <BR> <BR> <BR> <BR> -NHCOCH20H -NHCOCHOHCH3 -NH(COCHOHCH20H) -NH(COCHOHCHOHCH20H) -NH (COCHOHCHOHCH3) -NH (COCHOHCH2CH20H) -NH (COCH (CH20H) 2) -N (CH3) COCHOHCH20H -N (CH3) COCHOHCHOHCH20H -N (CH3) COCHOHCHOHCH3 -N (CH3) COCHOHCH2CH20H -N (CH3) COCH (CH20H) 2 -N (COCH3) H

-N (COCH3) C1_3-alkyl -N (COCH3)-mono, bis or tris-hydroxy Ci-alkyi -N (COCH20H)-mono, bis or tris-hydroxy C1 4-alkyl -N (COCH20H) 2 -CON(CH2CHOHCH20H) (CH2CH20H) -CONH-C (CH20H) 3 and -CONH-CH (CH20H) (CHOHCH20H) -CON (CH3) CH2CH20H -CON (CH3) CH2CHOHCH20H.

In general, the M groups will preferably each comprise a mono-or polyhydroxy Cl4-alkyl group, attached to a primary amide group, wherein the primary amide group is linked to the phenyl ring by either the carbon atom in the carbonyl group or by the nitrogen.

Alternatively, one or more of the M groups may be a C14 alkyl group substituted by at least one hydroxyl group and optionally linked to the phenyl ring via a carbonyl group, preferably-CH2OH or a propanediol.

Other such M groups as are conventional within the field of triiodophenyl X-ray contrast agents may also be used and the introduction of M groups onto iodophenyl structures may be achieved by conventional techniques.

Typically, the monomers of the present invention will contain one M1 group though they may contain two or three M1 groups, similarly the dimers will typically contain one Mi group per C6R5 moiety but each C6R5 moiety may have two or three M1 groups. For both monomers and dimers, it is preferred that the C6R5 moieties contains three R groups which are iodine atoms.

In the dimeric compounds of the invention, the linker group X is conveniently a bond or a 1 to 7, e. g.

1,2,3 or 4, membered chain comprising carbon, nitrogen, oxygen or sulphur atoms, e. g. a bond, a O, S, N or C one atom chain, a NN, NC, NS, CC or CO two atom chain,

or a NCN, OCN, CNC, OCO, NSN, CSN, COC, OCC or CCC three atom chain, for example: an oxygen atom or a group NR1, CO, SO2 or CR21; a group COCO, SOCR21,SO2NR1,CR21CR21,CR21NR1COCR21, or CR12O; a group NR1CONR1, CONR1CR12,OCOO,CONR1CO, CR12OCR12, OCR12CO, COCR1R1CO,CR12CR12CR12, CR12NR1CR12,orNR1SO2NR1;CR12OCO where Ru ils hydrogen or a C16-alkyl or alkoxy group optionally substituted by hydroxy, alkoxy, oxa or oxo (e. g. a polyhydroxyalkyl, formyl, acetyl, hydroxyl, alkoxy or hydroxyalkoxy group) and where it is attached to a carbon atom Rlmay also be a hydroxyl group.

Where X is a 2 to 7 membered chain it is preferably non-symmetric.

When X provides a 4-7 atom linkage, conventional linker groups, such as for example those suggested by Justesa in WO-93/10078 or Bracco in US-A-4348377 and WO- 94/14478, may be used.

In general such linkages will comprise optionally aza or oxa substituted alkylene chains optionally carrying R1 substituents, especially such groups terminating with imine nitrogen or, more preferably, carbonyl carbon atoms, preferably belonging to aminocarbonyl functional units within the chain.

Hydroxylated chains, such as are found in iodixanol are particularly preferred.

Examples of such chains are NCCN, NCCCN, CNCCCNC, and CNCCN, eg.

-NR1COCONR1- -NR1COCR12CONR1- -NR1CR12CR1OHCR12NR1- -CONR1CR12CONR1-and -N(COR1)CR12CR1OHN(COR1)-, eg as found in iotrolan, iofratol, ioxaglic acid and

iodixanol, or as otherwise indicated in WO-94/14478.

Preferably the compounds of the invention are monomers, i. e. n = 0, and preferred among the compounds of the invention are those of formula II wherein each group R'is a hydrogen atom or a hydrophilic moiety M or Mi as previously defined and R, is as previously defined. Preferably, each group R'is an M or Mi moiety.

Particularly preferred among the compounds of the invention are compounds of formulae III, IV and V.

wherein Ri is as previously defined and each R2 which may be the same or different is'a CI-4 hydroxyalkyl group, preferably at least one R2 group is a C2 4 polyhydroxyalkyl group.

The two R'2 groups between them will preferably contain 3 to 5, more preferably 4 hydroxyl groups. The preferred number of hydroxyl groups will typically depend on the contribution to water solubility of the Ri group and can therefore be adjusted accordingly.

In the compounds of formula (V), the R2 groups preferably each contain an even number of hydroxyl groups.

In the compounds of formula (IV), the R2 groups are preferably different.

Especially preferred compounds of the invention include, (N, N'-bis (hydroxyacetyl)-3,5-diamino-2,4,6- triiodomandeloamide), (N- (2, 3-dihydroxypropionyl)-N'-hydroxyacetyl-3,5- diamino-2,4,6-triiodomandeloamide), (N, N-bis (2,3-dihydroxypropionyl)-3,5-diamino- 2,4,6-triiodomandeloamide), (N- (2,3,4-trihydroxybutyryl)-N-hydroxyacetyl-3,5- diamino-2,4,6-triiodomandeloamide), particularly (N- (2R, 3S, 4-trihydroxybutyryl)-N'-hydroxyacetyl-3,5- diamino-2,4,6-triiodomandeloamide) and (N- (2R, 3R, 4- trihydroxybutyryl)-N'-hydroxyacetyl-3,5-diamino-2,4,6- triiodomandeloamide), (N, N'-bis (2,3-dihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide), (N, N'-bis (2,4-dihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide),

(N, N'-bis (2,2-bis (hydroxymethyl)-acetyl)-3,5- diamino-2,4,6-triiodomandeloamide), (N, N'-bis (2,3,4-trihydroxybutyryl)-3,5-diamino- 2,4,6-triiodomandeloamide), particularly (N, N'- bis (2R, 3S, 4-trihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide), and (5- (2,3-dihydroxypropionyl) amino-3-N- (2,3- dihydroxypropyl) carbamido-2,4,6-triiodomandeloamide).

An especially preferred compound is N- (2R, 3S, 4- <BR> <BR> <BR> trihydroxybutyryl)-N'-hydroxyacetyl-3,5-diamino-2,4,6- triiodomandelamide.

It should be appreciated that the invention relates to all stereoisomeric forms of a given compound of formula I as defined herein. The M1 group as defined herein contains one chiral center and M groups may also have chiral centers, giving rise to different diastereomers and enantiomers. In general, the physical and biological properties of the different stereoisomers do not differ widely and a particular contrast medium may contain a mixture of isomers of the active ingredient. In certain circumstances, e. g. relating to obtaining regulatory approval, it may be more convenient to prepare a contrast agent which contains a limited number of stereoisomers. Restrictions on the stereoisomers present in the final contrast medium may typically be a result of the chosen starting material which may be readily available in enantiomerically pure form.

The compounds of the invention may be prepared by any of the methods of synthesis of organic molecules known in the art and described in the literature.

Advantageously the compounds may be prepared by initial formation of a mandelic amide, then iodination of the phenyl ring and finally substitution of the phenyl ring with the solubilising groups M. Where desired the linker group X may be produced by modification, e. g.

substitution, oxidation or reduction, of a precursor linker, e. g. in a precursor monomer.

The compounds of the invention may be prepared by removal of a hydroxy or amino protecting group from a compound of formula I which additionally incorporates such a protecting group. Such a method of preparation constitutes a further aspect of the present invention.

A typical reaction scheme for the preparation of a compound according to the invention is shown below

The compounds of the invention may be used as X-ray contrast agents and to this end they may be formulated with conventional carriers and excipients to produce diagnostic contrast media.

Thus viewed from a further aspect the invention provides a diagnostic composition comprising a compound of formula I together with at least one physiologically tolerable carrier or excipient, e. g. in aqueous solution in water for injections optionally together with added plasma ions or dissolved oxygen.

The contrast agent compositions of the invention may be at ready-to-use concentrations or may be formulated in concentrate form for dilution prior to administration. Generally compositions in ready-to-use form will have iodine concentrations of at least 100mgI/ml, preferably at least 150 mgI/ml, with concentrations of at least 300mgI/ml, e. g. 320 to 600 mgI/ml or 400 to 550 mgI/ml being generally preferred.

The higher the iodine concentration the higher the diagnostic value but equally the higher the solution's viscosity and osmolality. Normally the maximum iodine concentration for a given compound will be determined by its solubility, and by the upper tolerable limits for viscosity and osmolality.

For contrast media which are administered by injection, the desirable upper limit for solution viscosity at ambient temperature (20°C) is 30mPas; however viscosities of up to 50 or even up to 60mPas can be tolerated although their use in paediatric radiography will then generally be contraindicated. For contrast media which are to be given by bolus injection, e. g. in angiographic procedures, osmotoxic effects must be considered and preferably osmolality should be below 1 Osm/kg H20, especially below 850 mOsm/kg H2O.

With the compounds of the invention, such viscosity, osmolality and iodine concentration targets can readily be met. It may however be desirable to

include plasma cations for their cardioprotective effect. Such cations will desirably be included in the ranges suggested in WO-90/01194 and WO-91/13636.

Preferred plasma cation contents for the contrast media of the invention, especially contrast media for angiography, are as follows: sodium 2 to 100, especially 15 to 75, particularly 20 to 70, more particularly 25 to 35 mM l calcium up to 3.0, preferably 0.05 to 1.6, especially 0.1 to 1.2, particularly 0.15 to 0.7mM potassium up to 2, preferably 0.2 to 1.5, especially 0.3 to 1.2, particularly 0.4 to 0.9 mM magnesium up to 0.8, preferably 0.05 to 0.6, especially 0.1 to 0.5, particularly 0.1 to 0.25 mM The plasma cations may be presented, in whole or in part, as counterions in ionic contrast agents.

Otherwise they will generally be provided in the form of salts with physiologically tolerable counteranions, e. g. chloride, sulphate, phosphate, hydrogen carbonate, etc., with plasma anions especially preferably being used.

Besides plasma cations, the contrast media may contain other counterions where the compound of formula I is ionic and such counterions will of course preferably be physiologically tolerable. Examples of such ions include alkali and alkaline earth metal ions, ammonium, meglumine, ethanolamine, diethanolamine, chloride, phosphate, and hydrogen carbonate. Other counterions conventional in pharmaceutical formulation may also be used. The compositions moreover may contain

further components conventional in X-ray contrast media, e. g. buffers, etc.

Viewed from a still further aspect the present invention provides a method of generating an enhanced image of at least part of a human or non-human animal body which comprises administering to said body a compound of formula I and generating an image of at least part of said body to which said compound distributes.

In a yet further aspect, the invention provides the use of a compound of formula I for the manufacture of a diagnostic composition for use in a method of diagnosis which involves generating an image.

Publications referred to herein are incorporated herein by reference.

The invention will now be described further with reference to the following non-limiting Examples.

Stereochemistry has been given for some examples but this should not be regarded in any way as limiting the compounds of the invention.

Example 1 (3,5-Dinitrobenzaldehyde) To a solution of oxalylchloride (26 ml, 0.30 mol) in CH2Cl2 (600 ml) DMSO (43 ml, 0.60 mol) was added, maintaining the temperature between-50°C and-65°C. To the reaction solution was then added 3,5-dinitrobenzyl alcohol (50g), in THF (100 ml), maintaining the temperature between-50°C and-65°C. The reaction mixture was stirred at-65°C for 30 minutes and then triethylamine (170 ml) was added at-50°C and-65°C. The reaction temperature was then adjusted to room temperature and H20 (800 ml) was added. The organic phase was washed with sat. NaHCO3 (500 ml), 5 times with

diluted HCl (300 ml) and finally brine. The organic phase was then dried over MgSO4 and the volatile solvents were removed at reduced pressure. The crude product was then triturated with heptane, which gave 45.8 g (89%) of 3,5-dinitrobenzaldehyde.

H-NMR (CDC13,300 MHz) 5 ppm: 10.22 (s, 1H), 9.30 (d, 1H), 9.05 (t, 2H).

Example 2 (3,5-Dinitro-O-trimethylsilylmandelonitrile) To a mixture of 3,5-dinitrobenzaldehyde (16.0 g, 81.6 mmol) and CH2Cl2 (16 ml) Zn (CN) 2 (30 mg, 0.26 mmol) and then trimethylsilylcyanide (12 ml, 90.0 mmol) were added at 0°C under an argon atmosphere. The mixture was stirred over night at room temperature. The solvent and the remaining trimethylsilylcyanide were removed at reduced pressure, which gave 23.4g (97%) of 3,5-dinitro- O-trimethylsilylmandelonitrile.

H-NMR (CDCl3,300 MHz) 5 ppm: 9.09 (t, 1H), 8.68 (d, 2H), 5.70 (s, 1H), 0.35 (s, 9H).

Example 3 (3,5-Dinitromandeloamide) 3,5-dinitro-O-trimethylsilylmandelonitrile (5.0 g, 16.9 mmol) and BF3-acetic acid complex (30 ml) were dissolved in H20 (5 ml) at room temperature. The reaction temperature was raised to 115°C immediately and stirred for 10 minutes. The reaction solution was then cooled to 0°C. H20 (100 ml) and EtOAc (200 ml) were added. The organic phase was washed with sat NaHC03 (100 ml) and brine (100 ml). Drying over MgSO4 was followed by removal of solvents at reduced pressure. The residue was crystallized from isopropylacetate. The crystalline

residue was left for preparative HPLC, which gave 2.2 g (54%) of 3,5-dinitromandeloamide.

1H-NMR (DMSO-d6,300 MHz) 5 ppm: 8.74 (d, 1H), 8.68 (t, 2H), 7.69 (s, 1H), 7.43 (s, 1H), 6.76 (d, 1H), 5.23 (d, 1H).

Example 4 (2,4,6-Triiodo-3,5-diaminomandeloamide) 3,5-Dinitromandeloamide (5.0 g, 20.8 mmol), PtO2 (50 mg, 0.22 mmol) and concentrated HCl (5 ml) were added to MeOH (100 ml) and H20 (10 ml). After hydrogenation for 1.5 hours, the catalyst was filtered off and the remaining solution was added to LiICl2 (70% in H20,24.3 g, 83.2 mmol) in H20 (50 ml). The reaction mixture was stirred for 15 minutes at room temperature. A brown precipitate was formed. The reaction was terminated with sat. NaHS03 (20 ml) and the precipitate was filtered off and washed several times with H20 and finally ether, yielding 9.2 g (79%) of 2,4,6-triiodo-3,5- diaminomandeloamide. 1H-NMR (DMSO-d6,300 MHz) 5 ppm: 7.37 (s, 1H), 7.15 (s, 1H), 5.65 (s, 1H).

Example 5 (0-Acetyl-2,4,6-triiodo-3,5-diaminomandeloamide) To 2,4,6-Triiodo-3,5-diaminomandeloamide (1.21 g, 2.165 mmol) and dimethylaminopyridine (14 mg) in 40 ml pyridine was added acetic anhydride (1.33 ml). The solution was stirred for 2 hours and 20 minutes and then the volatile substances were removed at reduced pressure. H20 (40 ml) was added and the solid was filtered off and washed with water. The crude material was sonicated for 10 minutes in 2: 3 CH3CN/H20 (25 ml).

The solid was filtered off and washed twice with 2: 3

CH3CN/H2O (2 ml), yielding 0.86 g (64%) of 0-acetyl- 2,4,6-triiodo-3,5-diaminomandeloamide.

H-NMR (DMSO-d6,300 MHz.) 5 ppm: 7.49 (s, 1H), 7.40 (s, 1H), 6.74 (s, 1H), 5.25 (s, 4H), 2.06 (s, 3H).

Example 6 (O-Acetyl-N, N-bis (acetoxyacetyl)-3, 5-diamino-2, 4 6- triiodomandeloamide and O-Acetyl-N- (2,3- diacetoxypropionyl)-N-acetoxyacetyl-3 5-diamino-2,4,6- triiodomandeloamide) To 0-acetyl-2,4,6-triiodo-3,5-diaminomandeloamide (530 mg, 0.88 mmol) in N, N'-dimethylacetamide (DMAC) (5 ml) was added acetoxyacetylbromide (204 mg, 1.13 mmol) at 0°C under argon atmosphere. After 8 minutes 2,3- diacetoxypropionylbromide (478 mg, 1.89 mmol) was added and the reaction solution stirred for a total time of 1 hour and then poured into an equivalent amount of NaHCO3 in H2O. The solution was saturated with NaCl and extracted three times with EtOAc (50 ml). The combined EtOAc phases were dried over Na2SO4 and the solvent was removed at reduced pressure. The residue was left for preparative HPLC, which gave 375 mg (49%) of O-Acetyl-N- (2,3-diacetoxypropionyl)-N'-acetoxyacetyl-3,5-diamino- 2,4,6-triiodomandeloamide (A) and 140 mg (20%) of O- Acetyl-N, N'-bis (acetoxyacetyl)-3,5-diamino-2,4,6- triiodomandeloamide (B). MS (ESP+, m/e): (A), 873 (M), 890 (M+H2O), 895 (M+Na). (B), 801 (M), 818 (M+H2O), 823 (M+Na).

H-NMR (CD3CN, 300 MHz) b ppm: (B) 8.70 (s, 2H), 6.88 (m, 2H), 6.32 (m, 2H), 4.72 (s, 4H), 2.17 (m, 9H).

Example 7 (O-Acetyl-N, N-bis (acetoxyacetyl)-3, 5-diamino-2, 4,6- triiodomandeloamide and O-Acetyl-N- (2R, 3S, 4- <BR> <BR> <BR> <BR> triacetoxybutyryl)-N-acetoxyacetyl-3,5-diamino-2,4, 6- triiodomandeloamide) To O-acetyl-2, 4,6-triiodo-3,5-diaminomandeloamide (660 mg, 1.10 mmol) in DMAC (6 ml) was added acetoxyacetylbromide (253 mg, 1.42 mmol) at 0°C under argon atmosphere. After 7 minutes 2R, 3S, 4- triacetoxybutyrylbromide (765 mg, 2.35 mmol) was added and the reaction solution stirred for 30 minutes at 0°C and 55 minutes at room temperature. The reaction solution was poured into sat. NaHC03 and then extracted three times with EtOAc (50 ml). The combined EtOAc phases were dried over Na2SO4 and the solvent was removed at reduced pressure. The residue was left for preparative HPLC, which gave 360 mg (35%) of O-Acetyl-N- (2R, 3S, 4-triacetoxybutyryl)-N'-acetoxyacetyl-3,5- diamino-2,4,6-triiodomandeloamide (A) and 200 mg (23%) of O-Acetyl-N, N'-bis (acetoxyacetyl)-3,5-diamino-2,4,6- triiodomandeloamide (B). MS (ESP+, m/e): (A), 945 (M), 962 (M+H2O). 967 (M+Na). (B), see example 6.

Example 8 (O-Acetyl-N-(2,2-bis(acetoxymethyl)-acetyl)-N'- acetoxyacetyl-3,5-diamino-2,4, 6-triiodomandeloamide) To 0-acetyl-2,4,6-triiodo-3,5-diaminomandeloamide (100 mg, 0.16 mmol) in DMAC (1 ml) was added acetoxyacetylbromide (28 ul, 0.24 mmol) at 0°C under argon atmosphere. After 1 hour 2,2-bis (acetoxymethyl)- acetylbromide (160 ul) was added and the reaction

solution stirred for 40minutes at 0°C. The reaction solution was poured into sat NaHCO3, and then extracted three times with EtOAc (50 ml). The combined EtOAc phases were dried over Na2SO4 and the solvent was removed at reduced pressure. The residue was left for preparative HPLC, which gave 30 mg (21%) of O-Acetyl-N- (2,2-bis (acetoxymethyl)-acetyl)-N'-acetoxyacetyl-3, 5- diamino-2,4,6-triiodomandeloamide. MS (ESP+, m/e): 887 (M), 904 (M+H2O), 909 (M+Na).

Example 9 (O, N, N-Triscrotonyl-3, 5-diamino-2, 4¢6- triiodomandeloamide) To crotonylbromide (2.41 g, 16.2 mmol) was added 2,4,6- Triiodo-3,5-diaminomandeloamide (1.5 g, 2.69 mmol) in DMAC (15 ml) at 0°C under argon atmosphere. The reaction solution was stirred for 2.5 hours and the volatile material was removed at reduced pressure. Diluted NaHCO3 (40 ml) and CH2Cl2 (70 ml) were added to the residue and the aqueous phase was extracted with further CH2Cl2 (30 ml). The combined organic phases were washed with diluted HC1 (50 ml) and twice with H2O (50 ml). After drying over Na2SO4 and removal of the solvent at reduced pressure, the formed crude product was left for preparative HPLC, which gave 1.15 g (58%) of O, N, N'- MS (ESP+, m, le): 763 (M), 780 (M+H2O), 785 (M+Na).

Example 10 (O, N, N-Tris (2, 3-dihydroxybutyryl)-S, 5-diamino-2, 4,6- triiodomandeloamide) To O, N, N-triscrotonyl-3,5-diamino-2,4,6- triiodomandeloamide (0.42 g, 0.55 mmol) in acetone/H2O (8

ml) was added N-methylmorpholine N-oxide (0.39 g, 3.31 mmol) and Os04 (0.02 g, 0.079 mmol) added at room temperature. After 2 hours H2O (4 ml) was added and the mixture was stirred over night. To the reaction mixture was added sat. NaHSO3 (0.2 ml) and the volatile material was removed at reduced pressure. The residue was taken up in MeOH/H2O (1: 3,15 ml) and Amberlyst 15 was added until the pH reached 2-3. The resin was filtered off and Amberlyst A 26 was added until the pH reached 6-7.

The resin was filtered off and the solvent removed at reduced pressure. The residue was left for preparative HPLC, which gave 0.33 g (69%) of O, N, N-tris (2,3- dihydroxybutyryl)-3,5-diamino-2,4,6-triiodomandeloamide.

MS (ESP+, m/e): 865 (M).

Example 11 (O N, N-Tris (2,3-Diacetoxypropionyl)-3, 5-diamino-2, 4, 6- triiodomandeloamide) To 2,3-Diacetoxypropionylbromide (26.5 g, 98.4 mmol) was added 2,4,6-Triiodo-3,5-diaminomandeloamide (9.2 g, 16.4 mmol) in DMAC (100 ml) at 0°C under argon atmosphere.

The reaction solution was stirred for 1 hour at room temperature and then added to diluted NaHC03 (300 ml) and EtOAc (300 ml). The aqueous phase was extracted twice with EtOAc (250 ml) and the combined organic phases were washed with brine (200 ml). After drying over MgSO4 and removal of the solvent at reduced pressure, the residue was dissolved in isopropylacetate (20 ml) and added to ice cooled isopropylether (200 ml). The formed precipitate was filtered off and left for preparative HPLC, which gave 14.0 g (79%) of O, N, N-tris (2,3- Diacetoxypropionyl)-3,5-diamino-2,4,6- triiodomandeloamide. MS (ESP+, m/e): 1075 (M), 1093 (M+H2O), 1097 (M+Na), 1162 (M+DMAC).

Example 12 (0, N, N-Tris (2R, 35, 4-triacetoxybutyryl)-3, 5-diamino- 2,4,6-triiodomandeloamide) To 2R, 3S, 4-triacetoxybutyrylbromide (3.15 g, 9.7 mmol) was added 2,4,6-Triiodo-3,5-diaminomandeloamide (0.676 g, 1.2 mmol) in DMAC (10 ml) at 0°C under argon atmosphere. The reaction solution was stirred for 2 hours at room temperature and then added to diluted NaHCO3 (100 ml) EtOAc (100 ml). The aqueous phase was extracted twice with EtOAc (50 ml) and the combined organic phases were washed with brine (50 ml). After drying over MgSO4 and removal of the solvent at reduced pressure, the residue was left for preparative HPLC, which gave 250 mg (16%) of O, N, N'-tris (2R, 3S, 4- triacetoxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide. MS (ESP+, m/e): 1165 (M-T), 1307 (M+H20).

Example 13 (O, N, N'-Tris (2, 4-diacetoxybutyryl)-3, 5-diamino-2, 4, 6- triiodomandeloamide) To 2,4-diacetoxybutyrylbromide (4.37 g, 16.4 mmol) was added 2,4,6-Triiodo-3,5-diaminomandeloamide (1.0 g, 1.79 mmol) in DMAC (6 ml) at 0°C under argon atmosphere. The reaction solution was stirred for 2.5 hour at room temperature and then added to sat. NaHCO3 (60 ml) and EtOAc (100 ml). The aqueous phase was extracted twice with EtOAc (50 ml) and the combined organic phases were washed 3 times with brine (50 ml). After drying over MgSO4 and removal of the solvent at reduced pressure, the residue was left for preparative HPLC, which gave 670 mg (33%) of O, N, N'-tris (2,4-diacetoxybutyryl)-3,5-diamino- 2,4,6-triiodomandeloamide.

Example 14 (O, N, N-Tris (2,2-bis (acetoxymethyl)-acetyl)-3, 5-diamino- 2, 4, 6-triiodomandeloamide) To 2,2-bis (acetoxymethyl)-acetylbromide (4.30 g, 16.1 mmol) was added 2,4,6-Triiodo-3,5-diaminomandeloamide (0.9 g, 1.61 mmol) in DMAC (5 ml) at 0°C under argon atmosphere. The reaction solution was stirred for 2 hours at room temperature and then added to sat. NaHCO3 (60 ml) and EtOAc (100 ml). The aqueous phase was extracted twice with EtOAc (50 ml) and the combined organic phases were washed 3 times with brine (50 ml).

After drying over MgSO4 and removal of the solvent at reduced pressure, the residue was left for preparative HPLC, which gave 620 mg (34%) of O, N, N'-tris (2,2- bis (acetoxymethyl)-acetyl)-3,5-diamino-2,4,6- triiodomandeloamide. MS (ESP+, m/e): 1117 (M), 1135 (M+H20).

General procedure for hydrolysis of polyacylated compounds The polyacylated compound was dissolved in a mixture of methanol and water containing NaOH (1 M, 1.2 mol- equivalents/acylated hydroxy group). After 1 hour Amberlyst 15 was added until the pH reached 2-3. The resin was filtered off and Amberlyst A 21 was added until the pH reached 6-7. The resin was filtered off and the solvents removed at reduced pressure. The residue was left for preparative HPLC.

Example 15 (N, N-Bis (hydroxyacetyl)-3, 5-diamino-2, 4, 6- triiodomandeloamide) O-Acetyl-N, N'-bis (acetoxyacetyl)-3,5-diamino-2,4,6- triiodomandeloamide (290 mg, 0.36 mmol) gave 210 mg (86%) of N, N-bis (hydroxyacetyl)-3,5-diamino-2,4,6- triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.76 (m, 2H), 7.42 (s, 1H), 7.26 (m, 1H), 6.64 (m, 1H), 5.83 (d, 1H), 5.57 (m, 2H), 3.99 (s, 4H). MS (ESP+, m/e): 675 (M), 692 (M+H2O), 697 (M+Na).

Example 16 <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> (N-(2, 3-Dihydroxypropionyl)-N-hydroxyacetyl-3, 5-<BR> <BR> <BR> <BR> <BR> <BR> diamino-2,4,6-triiodomandeloamide)<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> O-Acetyl-N- (2, 3-diacetoxypropionyl)-N'-acetoxyacetyl- 3,5-diamino-2,4,6-triiodomandeloamide (375 mg, 0.43 mmol) gave 250 mg (82%) of N- (2,3-Dihydroxypropionyl)- <BR> <BR> <BR> <BR> N'-hydroxyacetyl-3,5-diamino-2,4,6-triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.75 (m, 2H), 7.41 (s, 1H), 7.24 (m, 1H), 6.64 (m, 1H), 5.83 (d, 1H), 5.72 (m, 1H), 5.57 (m, 1H), 4.78 (m, 1H), 4.05 (m, 1H), 3.99 (s, 2H), 3.81 (m, 1H), 3.58 (m, 1H). MS (ESP+, m/e): 705 (M), 723 (M+H20), 727 (M+Na).

Example 17 (N, N-Bis (2,3-Dihydroxypropionyl)-3,5-diamino-2, 4,6- triiodomandeloamide) O, N, N'-Tris (2,3-Diacetoxypropionyl)-3,5-diamino-2,4,6- triiodomandeloamide (43.5g, 40.4 mmol) gave 18.4 g (62%) of N, N'-Bis (2,3-Dihydroxypropionyl)-3,5-diamino-2,4,6-

triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.70 (m, 2H), 7.39 (s, 1H), 7.23 (m, 1H), 6.62 (m, 1H), 5.82 (d, 1H), 5.70 (m, 2H), 4.77 (m, 2H), 4.05 (m, 2H), 3.77 (m, 2H), 3.57 (m, 2H). MS (ESP+, m/e): 735 (M), 752 (M+H2O), 756 (M+Na).

Example 18 <BR> <BR> (N- (2R, 35, 4-Trihydroxybutyryl)-N-hydroxyacetyl-3,5-<BR> diamino-2,4,6-triiodomandeloamide)<BR> <BR> O-Acetyl--N- (2R, 3S, 4-triacetoxybutyryl)-N'-acetoxyacetyl- 3,5-diamino-2,4,6-triiodomandeloamide (360 mg, 0.38 mmol) gave 250 mg (90%) of N- (2R, 35,4- Trihydroxybutyryl)-N'-hydroxyacetyl-3,5-diamino-2,4,6- triiodomandeloamide. 1H-NMR (DMSO-d6, 300 MHz) 5 ppm: 9.72 (m, 2H), 7.41 (s, 1H), 7.25 (m, 1H), 6.63 (m, 1H), 5.83 (d, 1H), 5.58 (m, 1H), 5.23 (m, 1H), 4.59 (s, 1H), 4.43 (m, 1H), 4.08 (s, 1H), 3.99 (s, 2H), 3.90 (m, 1H), 3.50 (m, 1H), 3.40 (m, 1H). MS (ESP+, m/e): 757 (M+Na) Example 19 (N,N'-Bis(2,3-dihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide) O, N, N-Tris (2,3-dihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide (1.19 g, 1.38 mmol) gave 100 mg (10%) of N, N'-Bis (2,3-dihydroxybutyryl)-3,5-diamino- 2,4,6-triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.68 (m, 2H), 7.39 (s, 1H), 7.23 (m, 1H), 6.63 (m, 1H), 5.84 (d, 1H), 5.43 (m, 2H), 4.51 (s, 2H), 3.97 (m, 2H), 3.78 (s, 2H), 1.18 (d, 6H). MS (ESP+, m/e): 763 (M), 780 (M+H2O), 785 (M+Na).

Example 20 (N, N-Bis (2,4-dihydroxybutyryl)-3, 5-diamino-2,4,6- triiodomandeloamide) O, N, N'-Tris (2,4-diacetoxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide (0.67g, 0.60 mmol) gave 430 mg (93%) of N, N'-Bis (2,4-dihydroxybutyryl)-3,5-diamino-2,4,6- triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.65 (m, 2H), 7.39 (s, 1H), 7.23 (m, iH), 6.63 (m, 1H), 5.83 (d, 1H), 5.57 (m, 2H), 5.23 (m, 1H), 4.47 (m, 2H), 4.12 (m, 2H), 3.59 (m, 4H), 2.00 (m, 2H), 1.76 (m, 2H). MS (ESP+, m/e): 763 (M), 785(M+Na).(M+H2O), Example 21 (N, N'-Bis (2, 2-bis (hydroxymethyl)-acetyl)-3,5-diamino- 2,4,6-triiodomandeloamide) O, N, N'-Tris (2,2-bis (acetoxymethyl)-acetyl)-3,5-diamino- 2,4,6-triiodomandeloamide (620 mg, 0.56 mmol) gave 182 mg (43%) of N, N'-Bis (2,2-bis (hydroxymethyl)-acetyl)-3,5- diamino-2,4,6-triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.90 (m, 2H), 7.39 (s, 1H), 7.24 (m, 1H), 6.59 (m, 1H), 5.82 (d, 1H), 4.57 (s, 4H), 3.82 (m, 4H), 3.67 (m, 4H), 2.68 (m, 2H).

Example 22 <BR> <BR> (N, N-Bis (2R, 3S 4-trihydroxybutyryl)-3, 5-diamino-2, 4, 6- triiodomandeloamide) O, N, N'-Tris (2R, 3S, 4-triacetoxybutyryl)-3,5-diamino- 2,4,6-triiodomandeloamide (250 mg, 0.20 mmol) gave 120 mg (75%) of N, N'-Bis (2R, 3S, 4-trihydroxybutyryl)-3,5- diamino-2,4,6-triiodomandeloamide.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.69 (m, 2H), 7.41 (s, 1H), 7.25 (m, 1H), 6.63 (m, 1H), 5.84 (d, 1H), 5.22 (m, 2H), 4.58 (m, 2H), 4.44 (m, 2H), 4.09 (m, 2H), 3.91 (m, 2H), 3.51 (m, 2H), 3.39 (m, 2H).

Example 23 <BR> <BR> <BR> <BR> <BR> <BR> (O-Acetyl-N-(2R 3R 4-triacetoxybutyryl)-N-<BR> <BR> <BR> <BR> <BR> acetoxyacetyl-3,5-diamino-2,4,6-triiodomandeloamide) O-Acetyl-2,4,6-triiodo-3,5-diaminomandeloamide (31.9 g, 53.0 mmol) was reacted first with acetoxyacetyl bromide (14.1 g, 79.5 mmol) and then with 2R, 3R, 4-tri- acetoxybutyryl bromide (43.1 g, 0.13 mol) according to the procedure in example 7. The amount of product isolated was 22.3 g (44 %).

MS (ESP+, m/e): 945 (M), 962 (M+H20).

Example 24 (N-(2R, 3R, 4-Trihydroxybutyryl)-N-hydroxyacetyl-3, 5- diamino-2,4 6-triiodo-mandeloamide) <BR> <BR> <BR> <BR> <BR> <BR> O-Acetyl-N-(2R, 3R, 4-triacetoxybutyryl)-N-acetoxyacetyl- 3,5-diamino-2,4,6-triiodomandeloamide (16.8 g, 17.8 mmol) was hydrolyzed, according to the general method above in Example 14 to give 12.4 g (95%) of product.

MS (ESP+, m/e): 735 (M), 743 (M+H20).

Example 25 (5-Amino-3-acetoxymethyl-2,4, 6-triiodobenzoic acid) 5-Amino-3-hydroxymethyl-2,4,6-triiodobenzoic acid (140.5 g, 0.26 mol) was dissolved in pyridine (450 ml) and dimethylaminopyridine (0.10g) was added. To this solution, with efficient stirring and cooling in an ice-

bath, was added dropwise acetic anhydride (300 ml).

After addition the reaction mixture was allowed to reach ambient temperature and after 4h the mixture was evaporated to dryness. The brown residue was trituated with acetone (3 x 150 ml), filtered and pumped dry.

Isolated 141 g (93%) of a yellow powder.

MS (ESP+, m/e): 587 (M).

H-NMR (DMSO-d6,300 MHz) 5 ppm: 5.43 (br. s, 2H), 5.35 (s, 2H), 3.45 (br. s, 1H), 2.03 (s, 3H).

Example 26 (5-rN-(2, 3-Diacetoxypropionyl) aminol-3-acetoxymethyl- 2 4,6-triiodobenzoic acid) < 5-Amino-3-acetoxymethyl-2,4,6-triiodobenzoic acid (141.0 g, 0.24 mol) was dissolved in N, N-dimethylacetamide (250 ml) and added slowly, with efficient stirring and cooling in an ice-bath, to 2,3-diacetoxypropionyl bromide. The temperature was then allowed to reach ambient temperature and after 5 h the reaction mixture was concentrated to ca. 1/3 of its volume in high vacuo, and below 60°C. The oily residue was slowly added to a well stirred solution of water (2.5 1, pH=2). The solid residue was dissolved in ethyl acetate (1.0 1) and the solution was washed with acidic water (2x 1.0 1, pH= 2) and neutral water (1.0 1). The organic phase was then extracted with a solution of NaHC03 (10%, ca 1.5 1) until pH of the aqueous phase reached 8. The aqueous phase was then acidified slowly with conc. hydrochloric acid (ca. 50 ml) to pH= 2, and extracted with ethyl acetate (2x 0.7 1). The organic phases were treated with activated charcoal (3 g), dried (MgSO4) and the solvent evaporated to give a light brown foam. This foam was dissolved in acetone (70 ml), toluene (ca. 150 ml) was added until the solution became turbid, and the solution was evaporated in vacuo on a rotatory

evaporator at a temperature < 30°C to ca. 1 of its volume. The precipitate formed was filtered off. The filtercake was dissolved again in acetone (70 ml) and the procedure repeated once giving after drying a nearly white powder of weight 160 g (88%).

H-NMR (CDC13,300 MHz) 6 ppm: 8.05 & 8.24 (2 s, 1H), 6.50 (br s, 1H), 5.67 (m, 1H), 5.56 (s, 2H), 4,72 (m, 1H), 4.52 (m, 1H), 2.28 (s, 3H), 2.11 (s, 3H).

Example 27 (5-rN-(2, 3-Diacetoxypropionyl) aminol-3-acetoxymethyl- 2,4,6-triiodobenzoyl chloride) 5- [N- (2,3-Diacetoxypropionyl) amino]-3-acetoxymethyl- 2,4,6-triiodobenzoic acid (160 g, 0.21 mol) was suspended in acetonitrile (180 ml). Thionyl chloride (61 ml, 0.84 mol) was added and one drop of N, N- dimethylformamide and the mixture was heated to 55°C with efficient stirring. After 2.5 h the mixture was evaporated to an oil, which was dissolved in methylene chloride (1.0 1). The organic solution was washed with water (2x 200 ml) and then stirred for 10 min. with a diluted solution of NaHC03 (2 %, 200 ml). The phases were separated and the organic phase dried (MgSO4), the solvent evaporated to give a solid residue, which was taken up in ethyl acetate (250 ml) and filtered through a pad of silica. After evaporation of solvent and drying under vacum there was 141 g (86%) of a foam.

H-NMR (DMSO-d6,300 MHz) 5 ppm: 7.99 (s, 1H), 5.68 (m, 1H), 5.57 (s, 2H), 4.72 (m, 1H), 4.51 (m, 1H), 2.27 (s, 3H), 2.12 (s, 6H).

Example 28 5-rN-(2, 3-Dihydroxypropionyl) aminol-3-hydroxymethyl- 2.4,6-triiodo-N-(2, 3-dihydroxypropyl) benzamide 5- [N- (2,3-Diacetoxypropionyl) amino]-3-acetoxymethyl- 2,4,6-triiodobenzoyl chloride (7.71 g, 9.9 mmol), 2,3- dihydroxypropylamine (1.48 g, 16.2 mmol), lithium bromide (90 mg, 1 mmol) and triethylamine (2.27 ml, 16.2 mmol) were mixed in tetrahydro-furan (55 ml) at ambient temperature., The temperature was increased to 65°C and held there for 26 h with efficient stirring, and the mixture was then evaporated to dryness. The residue was dissolved in a mixture of water and methanol (6: 1,70 ml) and treated with a strongly basic anion exchange resin (Dowex lx8) for 2.5 h. The resin was filtered off, the solution diluted with further water (50 ml) and treated with a strongly acidic cation exchange resin (Amberlyst 15) to bring the pH of the solution to 5.5- 6.0. The resin was filtered off and the solution was treated with activated charcoal (0.35 g), filtered and evaporated to a light yellow to white solid residue.

This was trituated with acetontrile (20 ml) for 12 h, giving 5.8 g (70%) of a white crystalline residue.

MS (ESP+, m/e): 706 (M).

Example 29 (5-(2, 2-Dimethyl-1, 3-dioxolane-4-carbamido)-3- hydroxymethyl-N-(2, 2-dimethyl-1, 3-dioxolane-4-methyl)- 2,4,6-triiodobenzamide) 5- (2,3-Dihydroxypropionyl) amino-3-hydroxymethyl-2,4,6- triiodo-N- (2,3-dihydroxy-propyl) benzamide (26.0 g, 36.8 mmol), acetone (470 ml), 2,2-dimethoxypropane (50 ml) and a strongly acidic ion exchange resin (Amberlyst 15) were all mixed and stirred at ambient temperature until

a clear solution was formed (ca. lh). The resin was filtered off, the filtrate was then filtered through a pad of dry NaHC03and then evaporated to give an oil.

Trituation with diisopropyl ether (80 ml) left a white precipitate which was filtered off giving 28.3 g (98 %).

'H-NMR (CDC13,300 MHz) b ppm: 8.35 (s, 1H), 6.37 (m, 1H), 5.19 (s, 2H), 4.66 (t, 1H), 4.36 (m, 2H), 4.10 (m, 1H), 3.82 (m, 2H), 3.44 (m, 2H), 1.51 (s, 3H), 1.45 (s, 3H), 1.39 (s, 3H), 1.33 (s, 3H).

Example 30 <BR> <BR> (5- (2, 2-Dimethyl-1,3-dioxolane-4-carbamido)-3-formyl-N-<BR> (2, 2-dimethyl-1, 3-dioxolane-4-methyl)-2,4,6- triiodobenzamide) 5-(2, 2-Dimethyl-1,(2, 2-Dimethyl-1, 3-dioxolane-4-carbamido)-3- hydroxymethyl-N- (2, 2-dimethyl-1,3-dioxolane-4-methyl)- 2,4,6-triiodobenzamide (82.6 g, 0.11 mol), pyridinium chloro-chromate (40.1 g, 0.19 mol) and molecular sieves (4 A, powder, 80.2 g) were all mixed in methylene chloride (3.2 1) and stirred well at ambient temperature. After 2.5 h the mixture was filtered and the filtrate stirred with a solution of NaHCO3 (10 %, 2 1) for 1 h. The phases were separated, the aqueous phase washed with further methylene chloride (2x 0.5 1). The organic phases were back extracted with water (1.0 1) and then filtered through a pad of silica.

The solvent was evaporated and the residue pumped in vacuo to give 59.5 g (72 %) of a slightly green powder.

H-NMR (CDC13,300 MHz) 5 ppm: 9.53 (s, 1H), 8.44 (s, 1H), 6.41 (s, 1H), 4.66 (t, 1H), 4.39 (m, 2H), 4.10 (m, 1H), 3.81 (m, 2H), 3.48 (m, 2H), 1.67 (s, 3H), 1.46 (s, 3H), 1.42 (s, 3H), 1.33 (s, 3H).

Example 31 <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> (5-(2, 2-Dimethyl-1, 3-dioxolane-4-carbamido)-3-(O-<BR> <BR> <BR> <BR> <BR> <BR> <BR> trimethylsilyl-cyanomethyl)-N-(2, 2-dimethyl-1 3-<BR> <BR> <BR> <BR> <BR> <BR> <BR> dioxolane-4-methyl)-2,4,6-triiodobenzamide)<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> 5- (2, 2-Dimethyl-1,3-dioxolane-4-carbamido)-3-formyl-N- 4,6- triiodobenzamide (58.4 g, 74.5 mmol), trimethylsilyl cyanide (40 ml, 0.32 mol) and a catalytic amount of zinc iodide (100 mg, 0.31 mmol) were all mixed and stirred at ambient temperature for 6 h. The mixture was then evaporated to dryness and pumped in high vacuo over night. The yield seem to be quantitative (according to NMR) and the product (60.4 g) was used directly in next step.

H-NMR (DMSO-d6 300 MHz) 5 ppm: 8.31 (s, 1H), 6.41 (s, 1H), 5.91-6.20 (m, 1H), 4.68 (m, 1H), 4.38 (m, 2H),. 4.12 (t, 1H), 3.83 (m, 2H), 3.47 (m, 2H), 1.66,1.69 (2s, 3H), 1.47,1.45 (2s, 6H), 1.35,1.25 (2s, 3H), 0.27 (br s, 9H).

Example 32 (5-(2, 3-Dihydroxypropionyl) amino-3-N-(2,3- dihydroxypropyl) carbamido-24,6-triiodomandeloamide and 5-(2, 3-dihydroxypropionyl) amino-3-carbamido-2, 4g6- triiodomandeloamide) The reaction product from Example 31 (60.4 g) was treated with conc. hydrochloric acid (100 ml) for 5 h.

The mixture was first evaporated to 1/3 of its volume, then diluted with water (700 ml), neutralized with a basic ion exchange resin (Amberlite A) to pH =7, evaporated to dryness and then left for preparative HPLC purification. 22.5 g (40.3 % over two steps) of 5- (2,3- dihydroxypropionyl) amino-3-N- (2,3-dihydroxypropyl)- carbamido-2,4,6-triiodomandeloamide was isolated.

MS (ESP+, m/e): 749 (M), 767 (M+H2O).

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9.71 (s, 1H), 8.48 (m, 1H), 7.41,7.24 (2s, 2H), 6.57 (s, 1H), 5.74 (d, 2H), 4.79 (s, 1H), 4.68 (d, 1H), 4.45 (m, 1H), 4.06 (m, 1H), 3.39-3.78 (m, 5H), 3.13-3.26 (m, 2H).

There was also isolated 1.4 g of 5- (2,3- dihydroxypropionyl) amino-3-carbamido-2,4,6- triiodomandeloamide.

MS (ESP+, m/e) : 675 (M).

H-NMR (DMSO-d6,300 MHz) 5 ppm: 9 68 (s, 1H), 7.93,7.83 (2s, 1H), 7.56 (s, 1H), 7.39 (s, 1H), 7.22 (s, 1H), 6.57 (m, 1H), 4.78 (s, 1H), 4.06 (m, 1H), 3.77 (m, 1H), 3.57 (m, 1H).

Example 33 (2, 3-Diacetoxypropionyl) 3- dibenzyl acetate) To 2,3-diacetoxypropionylbromide (10.5 g, 41.6 mmol) in a flask was added 5-amino-2,4,6-triiodo-1,3-dibenzyl

acetate (9.0 g, 14.6 mmol) dissolved in DMAC (15 ml) with cooling in an ice-bath. The temperature was allowed to reach ambient temperature with efficient stirring. After 4 h the mixture was added slowly to a well stirred aqueous solution of NaHCO3 (5%, 100 ml). A light tan colored precipitate was formed and filtered off. The filtercake was dissolved in methylene chloride (40 ml) and applied to a column of alumina. After elution and evaporation of the solvent there was 9.6 g (84 %) of a white compound.

1H-NMR (CDC13,300 MHz) 5 ppm: 7.96 (s, 1H), 5.68 (m, 5H), 4.73 (m, 1H), 4.52 (m, 1H), 2.27 (s, 3H), 2.12 (s, 6H), 2.10 (s, 3H).

MS (ESP+, m/e): 787 (M), 804 (M+H2O).

Example 34 (5- (2, 3-Dihydroxypropionyl) amino-2,4,6-triiodo-1, 3- dibenzyl alcohol) 5- (2,3-Diacetoxypropionyl) amino-2,4,6-triiodo-1,3- dibenzyl acetate (6.76 g, 8.59 mmol) was dissolved in methanol (100 ml) and sodium hydroxide (1.38 g, 34.3 mmol) dissolved in water (5 ml) was added dropwise with stirring. After 1.5 h the mixture was diluted with water (60 ml) and then treated with a strongly acidic ion exchange resin (Amberlyst 15 ca. 45 g) to bring pH to neutral. The resin was filtered off and the filtrate evaporated to dryness leaving a crystalline product of 5.58 g (quantitative yield).

MS (ESP+, m/e): 619 (M).

Example 35 (5-(2,2-Dimethyl-1,3-dioxolane-4-carbamido)-2,4,6- triiodo-1, 3-dibenzyl alcohol) 5- (2,3-Dihydroxypropionyl) amino-2,4,6-triiodo--1,3- dibenzyl alcohol (10.4 g, 13.2 mmol) was suspended in acetone (270 ml) and conc. sulfuric acid (3 ml) was added. The mixture was strirred for 40 h at ambient temperature until a clear solution was formed. The mixture was concentrated to ca 70-80 ml and diluted with a solution of NaHCO3 (5 %, 100 ml), and the resulting solution was extracted with ethyl acetate (2x 100 ml).

The organic phases were dried (NaSO4) and the solvent evaporated to give 7.1 g (82 %) of a white crystalline product.

H-NMR (CDCl3,300 MHz) 5 ppm: 8.38 (s, 1H), 5.24 (s, 4H), 4.66 (t, 1H), 4.35 (m, 2H), 1.67 (s, 3H), 1.46 (s, 3H).

MS (ESP+, m/e): 659 (M), 676 (M+H2O).

Example 36 <BR> <BR> (5-(2, 2-Dimethyl-1, 3-dioxolane-4-carboxamido)-2, 4, 6-<BR> triiodo-1, 3-dibenzaldehyde)<BR> <BR> 5- (2, 2-Dimethyl-1,3-dioxolane-4-carboxamido)-2,4,6- triiodo-1,3-dibenzyl alcohol (1.40 g, 2.12 mmol), pyridinium chlorochromate (1.78 g, 8.27 mmol) and molecular sieves (4 A powder, 4.0 g) were all mixed in methylene chloride (40 ml), refluxed for 4h and then stirred over night at 45°C. The mixture was filtered and worked up as described above in example 30. After work up there was 0.80 g (58%) of a light yellow crystalline product.

H-NMR (CDC13,300 MHz) 5 ppm: 9.61 (s, 2H), 8.32 (s, 1H), 4.71 (m, 1H), 4.40 (m, 2H), 1.69 (s, 3H), 1.47 (s,

3H).

MS (ESP+, m/e): 655 (M), 672 (M+H20).

Example 37 <BR> <BR> (5-(2, 2-Dimethyl-1 3-dioxolane-4-carboxamido)-2,4,6-<BR> triiodo-1, 3-bis (O-trimethyl-silylcyanomethyl)-benzene)<BR> <BR> 5- (2, 2-Dimethyl-1,3-dioxolane-4-carboxamido)-2,4,6- triiodo-1,3-dibenzaldehyde (0.12 g, 0.18 mmol), trimethylsilyl cyanide (2.0 ml, 1.5 mmol) and a catalytic amount of zinc iodide (0.02 g, 0.06 mmol) were all mixed and stirred at ambient temperature for 24 h.

The mixture was then evaporated to dryness and pumped in high vacuo for 10 h. The crude product (0.16 g), was used directly in next step without purification.

H-NMR (CDC13,300 MHz) 5 ppm: 6.59 (m, 3H), 4.61 (m, 1H), 4.12 (m, 2H), 0.09 (s, 9H), 0.05 (s, 9H).

Example 38 (5-(2,3-Dihydroxypropionyl)amino-2,4,6-triiodo-1,3- bis (hydroxy-carbamidomethyl) benzene) 5- (2, 2-Dimethyl-1,3-dioxolane-4-carbamido)-2,4,6- triiodo-1,3-bis- (0-trimethylsilyl-cyanomethyl) benzene was treated and worked up according to the procedure in example 32. The product was isolated in 7% yield.

MS (ESP+, m/e): 705 (M), 723 (M+H2O).

Example 39 Determination of viscosity The apparatus consisted of a thermostated 10 Hl graduated sample syringe connected to a conical shaped 100 Al sample vial. The syringe needle as well as a probe for temperature measurements (0.2°C) was inserted through an airtight septum at the top of the vial.

Through the septum was also inserted a small tubing connected to an air syringe via a PTFE tubing.

To determine viscosity, 15-75 yl of the sample liquid was placed at the bottom of the sample vial. The liquid was forced up into the sample syringe by a slight over pressure generated manually by the air syringe. When the syringe was almost filled, the over pressure was released so the liquid, forced only by gravity, could flow freely out from the syringe back into the vial.

The time for the liquid surface to pass between the marks of e. g. 5 and 10 Hl in the syringe was measured.

The viscosity is calculated as follows: ns=nR (dS/dR) (tS/tR) nus= Viscosity of the sample nR= Viscosity of a reference sample with known viscosity and with similar composition as the sample e. g. Iohexol or Iodixanol ds= Density of sample solution dR= Density of reference solution ts= Average time for sample surface to pass between two marks in the syringe tR= Corresponding time for reference sample

The results of these determinations of viscosity for various of the present Examples and two commercially available X-ray contrast media are shown in Table 1 below. In all cases, the values refer to concentrations of 350 mgI/ml at a temperature of 20°C.

Table 1 Example Viscosity (mPas) 15 6. 9 166.9 17 7.4 18 9.7 19 13.4 20 15.0 21 11.8 22 17.0 24 8.8 31 7. 5 32 10.1 Iohexol 20. 4- Iomeprol'15.4 Data from M. J. Kern, R. A. Roth, F. V. Aguirre, G.

Beauman, R. Vogel: American Heart Journal, Vol 123 (1)-, 160-165,1992.

2 Data from A. Gallotti, F. Uggeri, A. Favilla, M.

Cabrini, C. de Haen: European Journal of Radiology, Vol 18 (suppl 1), S1-S12,1994.