IE62582B1 - Nitrogen-containing cyclic ligands, metallic complexes formed by these ligands, diagnostic compositions containing these complexes and process for the preparation of the ligands - Google Patents

Abstract

Ligands and complexes of the title and the applications of these complexes in magnetic resonance imaging, in X-ray radiology and as in-vivo chemical shift agents.

Description

This invention relates to naw nitrogen-containing cyclic ligands and metallic complexes formed by these ligands, the uses of these complexes as magnetic resonance imaging agents, as X-ray contrast agents and as chemical shift reagents in vivo» The invention also relates to a process for the preparation of th® ligands.

EP-A-0 124 766 describes a contrast agent for MRI comprising a paramagnetic compound and, in particular, a polyamine. 1Q FR-A-2 539 996 describes a diagnostic agent formed by the anion of a complexing acid and one or more central ions of elements having atomic numbers 21 to 29, 42, 44 or 57 to 83.

WO-A-8 602 352 describes chelates of gadolinium with a compound selected from DOTRA, DOTA and ΝΟΤΑ.

No document, however, describes cyclic nitrogen-containing ligands which incorporates a substituent on a carbon atom of the large ring.

Thus, the invention relates to a ligand having the formula: HOOC -CH CM ·——COOH I HOOC -CH in which R, represents a radical of formula: — (ϋΗ2)Μ— CH—CH — I I R0 Rz R6 being selected from a cicu alkyl group, a hydroxyalkyl group and a C^C^, polyhydroxyalkyl group and a group having the formula: CH-COOH R,, being selected from groups A and groups of formula — (0¾) „ — Y—A-—¥ — — A being selected from C^-Cg alkylene groups, C^-Cg hydroxyalkylene and C^-Cg polyhydroxyalkylene groups, y being selected from ~ C - 0 - and - o - and t = l to · 4 I being selected from a hydrogen atom, a alkyl group, a C3-Ca hydroxyalkyl group and a 0,,-0. polyhydroxyalkyl group, m — 0 or 1 Rj, Rj, R4, which may be identical or different, represent a radical of the formula: -(CH)p— CH — I I Re R, Rj and which may be identical or different, being selected from a hydrogen atom, a C,-Cw alkyl group, a C.j-C4 hydroxyalkyl group and a C/-C, polyhydroxyalkvl group, p = 1 or 2 n = 0, 1 or 2 and is selected from a hydrogen atom, a C^-C^ alkyl group, a c,4C, hydroxyalkyl group and a CpC, poly hydroxy alkyl group, and z is selected from an oxygen atom and a group having the formula ?> » - »« Rw being selected from a hydrogen atom, a CpC,, alkyl group, a C,—fC4 hydroxyalkyl group, a polyhydroxyalkvl group, a group of formula - CH - COOH, Rj I having the meaning given previously, and a group having the formula / R 'X h CH-COOH Ί N ——— R s J CH-COOH \ i / f>3 w V CH-COOH R12 being selected from C^Cg alkylene, C^-Cg hydroxyalkylene and C^-Cg polyhydroxyalkylene groups, and their salts.

The ligands of formula I can be prepared by reacting a compound of formula: X — CH — COOH II I Rg in which Rs has the meaning given above and X represents a labile group such as a chlorine, bromine or iodine atom or a tosyloxy group or a mesyloxy group,, with a cyclic amine of the formula: H M W-- E? -Z 2 H in which Stj Rg, and n have the meanings given above, R*1 represents a radical of the formula: —^5." CH — CH — S I R7 Κ?ό being selected from a C^-C.^ alkyl group, a C.-Ct 15 hydroxyalkyl (group, a C^-C, polyhydroxyalkyl group and a group having the formula « - N « 8 H r2, Ra, Rz, Rn, m, n, having the meanings given above and Z' being selected from an oxygen atom and a group having the formula: > N~ R'w R'1O being selected from a hydrogen atom, a c^-c^ alkyl group, a C^-C. hydroxyalkyl group, a Ct-C, polyhydroxyalkyl group, and a group having the formula: Μ H H Rv Kg, Ft,, a4, r,2 and n having the meanings given above.

The ligands of formula I can also be prepared by means of a strecker reaction, by reacting a cyclic amine of formula III with an aldehyde of formula: Rj - CHO Ila in which has the meaning given previously, io the presence of hydrogen cyanide or more usually cyanide ions (Kcsr, NaCN).

The compounds of formula III in which is a > s - H,„ group can. be prepared a) by reacting a polyamine of formula: o in which n, R', and R, have the meanings given previously and R‘ represents a tosyl, mesyl or benzene sulfonyl group, with a compound of formula: X — Rg — N — Rg — X V I R' in which Rg, R~ and R£i have the meanings given previously and X represents a labile group such as a tosyloxy or mesyloxy group or a chlorine or bromine or iodine atom, or b) by reacting a diamine of formula: R?KN — R', — NH - R' X in which R*, and R' have the meanings indicated previously, with a compound of formula: This cyclisation reaction is carried out advantageously in the presence of a phase transfer catalyst.

The polyamines of formula IV can be obtained from dihvdroxylamines according tc< the following scheme: Η V R ’ Cl/pyridine R.

B’HN Jj j >& — R*., — w, vni J Π j Reduction h5 pq/c R 3 - WH2 IX n v/ B‘Cl/ayrit3ine " N I—— Q * WHS? JV -n As an alternative, phthalimide is made to react with the compounds of formula VII and hydrazinolysis is carried out in order to convert the compounds of formula VII into the compounds of formula IX.

The compounds of formula III containing 2 nitrogen-containing rings can foe prepared according to th© procedures specified previously.

Thus, it is possible to react a poly-amine of the formula: XI Ϊ CH — CH MH it R’WH NM 8* in which A and Rt? have the meanings given previously, with a compound of formula XI in order to obtain a compound of formula III in which is a group A.

The polyamine of formula XII can he prepared from a tetrahalogenated derivative by nucleophilic substitution in the presence of.sodium azide followed by a reduction in the presence of hydrogen and palladium on charcoal» As as alternative, the compounds &£ formula I composed of 2 nitrogen-containing rings and in which is a group &t can be prepared by condensation of a compound of formula: Cc ooc COO et Cm — a —CH ec ?oc with a polyaaine of formula: Χίίϊ Coo Εε H M - «3 - N X2V ra followed fey reduction with diborane according to a procedure described by Tabushi et al» (Tetra Letters 12, 1©49, 1977).

The compounds of formula I composed of 2 nitrogen-containing rings are then prepared from compounds of formula III with 2 rings as described previously.

As an alternative, compounds of formula I composed of 2 5 nitrogen-containing rings can be prepared by condensation of a compound of formula I in which R, is a radical of formula: — (°Η2)»~ CHCH I I Rg Ry in which R6 is a hydroxyalkyl group, with an activatable bifunctional compound of formula: X, — A — X, X,3 being a COOH group, a COCl group or an acid anhydride.

The compounds of formula I having 2 nitrogen-containing rings can also be prepared by condensation of a compound of formula; HOOC — CM CM - COOH I" — Ml XV w — « [« HOOC — CM in which R, is a radical of formula: — (ΟΗ2)β — CH — CH — R"6 r7 at and R™ having the meanings given previously and R6 being selected from a C,~C, alkyl group, a c,-c4 hydroxyalkyl group and a c,-c, polyhydroxyalkyl group, with a compound of formula: X - R'12 - X XVI X having the meaning given previously and R'12 representing an R1Z group which may be protected.

Compounds of the formula: ί 5 HOOC — CM CH --COOH HOOC — CH J? § 5 CH-COOH -I \ R" HOOC —CH 5 f? ..

-W « CH ~COOH are obtained in this way.

In addition, this invention relates to complexes formed by ligands of formula I with metal ions chosen from among the lanthanide ions (atomic numbers 57 to i|, transition metal ions (atomic numbers 21 to 29), in particular Mn2*, and Cr3*, and metal ions with atomic numbers 55» 56» 82 and 83» as well as the salts of these complexes with pharmaceutically acceptable mineral or organic bases or basic amino acids11 In these complexes, the metal ions are preferably gadolinium, europium, dysprosium, iron (Fe3*) and manganese (Mn2*).

As examples of salts mention may be made of those formed with sodium hydroxide, M-methylglucamine, diethanolamine, lysine and arginine.

The complexes can be prepared by reacting ligands with a metal salt or metal oxide in an aqueous solvent, with neutralisation, if necessary, in order to form a salt.

It should be evident that this invention includes not only the ligands of formula I and the complexes defined above in the form of racemic mixtures, but also th© stereoisomers of these ligands and complexes.

The complexes according to the invention can, in addition, be attached to a macromolecule which can become bound preferentially to an organ. Thus, the complexes according to the invention can be linked to proteins and in particular to antibodies.

In addition, they may also be encapsulated, particularly in liposomes.

The complexes according to the invention formed by the ligands of formula 1 with paramagnetic ions and their salts with pharmaceutically acceptable bases can be used as magnetic resonance imaging agents and as chemical shift reagents in vivo.

Th® complexes according to the invention formed by ligands of formula 1 with lanthanide ions (atomic number© 57 to 71) or ions of metals with atomic numbers 55, 56, 82 and 83 and their salts with pharmaceutically acceptable bases can be used as Xray contrast agents. For this purpose, the complexes formed with the following metal ions are particularly preferred: Gd, Sr, Dy, Tb, Ce, La, 3a and Cs.

Consequently, this invention also relates to a diagnostic composition which can be administered to man, comprising at 5 least one complex formed by a ligand of formula I with metal ions selected from the lanthanide ions, transition metal ions and metal ions with atomic numbers 55, 55, 82 and 83, as well as th® salts of these complexes with pharmaceutically acceptable mineral or organic bases, or with basic amino 10 acids.

These compositions can be constituted in particular by solutions of a complex according to the invention in a physiologically acceptable aqueous solvent.

The diagnostic compositions according to the invention may be administered: by the parenteral rotate, including the intravenous route, the intra-arterial route, the intra-lymphatic route, the sub-cutaneous route - fey the oral route, -fey the sub-arachnoid route, by the intrabronchial route in the form of an aerosol, - fey th® intraarticular route, - locally for the visualisation of cavities (e.g., the uterus).

In imaging fey magnetic resonance, the doses ar© very variable depending on the routes of administration.

For the intravenous or intra-arterial route, the dose is about 0.01 to 2mM/kg.

For the oral route, this dose may be as much as 10 mK/kg.

For the other routes of administration, the doses used are usually lower than ImM/kg and for the sub-arachnoid route they are usually even below 0.05 mM/kg.

The doses are the same for use as chemical shift reagents in vivo and as contrasting agents in X ray radiology, except by the intravenous or intra-arterial routes where the doses may up to 5mM/kg.

In addition, the complexes according to the invention formed by the ligands of formula ϊ with radioactive ions, as well as their gaits with pharmaceutically acceptable bases, can be used as diagnostic agents or therapeutic agents in nuclear medicine. Examples of radioactive ions are radioisotopes of elements such as copper, cobalt, gallium, germanium, indium and, above all, technetium (Tc 99 m).

The following examples illustrate the preparation of the compounds according to this application.

In these examples: - The NMR spectra were obtained on a Varian EH 360 machine at 60 KKz with TMs as internal reference. Unless otherwise indicated the solvent is COC13.

- The IR spectra were obtained on a Perkins-Elmer 1320 apparatus. The spectra of the solids were recorded in the fora of KBr pellets, in the case of liquids (oils) they were recorded in the absence of solvent.

- The term buffer used in thin layer chromatography designates a mixture of 1.5 Μ NBOH and 1.5 M (NH4) 2CO3„ The melting points were measured on a Xofler block.

" The terms used relating to analyses during complexation: '’absence of free Gd3* and of free ligands" are to be understood within the limits of detection of the methods used, i.e. <4 ppm and <5 ppm for Gd3* and ligand, respectively.

Example 1 - Preparation of 2,6-dimethvl-l, 4., 7, IQr tetraazacvclododecane-Na.,NM.;,Nwf-tetraacetic acid a) Preparation of N-tosyl-bis (2-tosyloxy propyl) amine.

A solution of 53.2 g (0.4 mole) of diiso-propanolamine in 50 cm3 of pyridine was added dropwise with cooling to a solution of 248 g (1.3 mole) of tosyl chloride in 200 cm3 of pyridine at 0®C so that the temperature was maintained between 0 and 5®C. The mixture was left at this temperature for 72h. It was then poured into 2 1 of water plus ice and 250 cm3 of concentrated hydrochloric acid.

The tosylated derivative was extracted with 2 1 of methylene chloride. The organic phase was dried over sodium sulphate, filtered, then decolourised with 3 SA charcoal and refiltered through a bed of silica. After evaporation of the solvent 193.3 g of a yellow oil remained (yield 81%; Rf ~ 0.7 silica/CSgCl2/acetone/98/2), and this used in the next step without purification. spectrum : 6H CK3 (doublet 1.2 and 1.3 ppm); 9H CH3 tosyl (singlet 2-5 ppm); 4H CH, (multiplet centred on 3.3 ppm); 2H Ora (quadruplet between 4.7 and 5.1 ppm); 12H aromatics (multiplet 7.3 and 3 ppm) . b) Preparation of N-tosyl-bis (2-azido propyl) amine. 65.1 g of sodium aside (1 mole) were added to 193.3 g (0.32 mole) of the compound obtained in jg in 1.2 1 of acetonitrile and 300 cm3 of water were added. The mixture was stirred and - 15 heated at 75°C for 48h. After cooling, the acetonitrile was evaporated in a vacuum.

The residue was taken up in 1 1 of methylene chloride. The organic phase was washed with water, dried and filtered through a bed of silica (200 g). After evaporation 82 g of a clear yellow oil remained (yield 75%; Rf « 0.85 silica Cn2CX2/acetone/92/2J sufficiently pure to be used directly.

IR spectrum N3 = 2100 cm'1 intense. c) Preparation of N-tosyl-bxs (2-amino propyl)amine. 82.2 g (0.244 mole) of the compound obtained in b were dissolved in 500 ca? ©f ethanol containing 8 g of 5% palladium on charcoal at 50% humidity.

The mixture was stirred vigorously while a gentle stream of hydrogen was passed through (removal of the nitrogen released). After 8h at ambient temperature, TLC showed the aside group to be absent. The mixture was then filtered and evaporated. 68.4 g of a clear yellow oil were obtained (yield 98.5%; Rf « 0.6 silica/HeOH/MH&OH.95/5), and this was used without purification.

NHR spectrum : 6H 0¾ (doublet 0.9 and l ppm) ; 3H 0¾ tosyl (singlet at 2.4 ppm); 6H CH, and CH (complex multiplet between 2.7 and 3.2 ppm); 4H aromatics (multiplet between 7.1 and 7.7 ppm) . d) Preparation of N-tosyl-bis/2 (tosylamino)propyl/amine. g (0.5 mole) of tosyl chloride were added in portions to 68.4 g (0.24 mole) of the amine obtained in e in 500 cm3 of methylene chloride and 70 car5 (0.5 mole) of triethylamine at 0°C. After the addition was complete, the mixture was stirred for 6h at ambient temperature. The reaction mixture was then washed with 500 cm3 of water, the organic phase was dried, evaporated to dryness and the residue was chromatographed on a column of silica with pure methylene chloride, then with a methylene chloride/methanol/98/2 mixture. The fractions of interest were evaporated and the solid residue was recrystallised from ethanol. After filtration and drying the aass obtained was 99.1 g (yield 70%).

NMR spectrum : SH CH- (doublet o,S, 1 ppm); 9H CH- p-tosyl (singlet 2.4 ppm); 4H €3¾ (triplet centred on 2.9 ppm); 2H CH (doublet 3.3 and 3.5 ppm); 12H aromatics (multiplet centred on 7.4 ppm) . e) Preparation of N-tosyl-bis (2-tosyloxyethyl)amine.

A solution of 32.5 g (0.31 mole) of diethanolamine in SO end of pyridine was added slowly to a solution of 185 g (0.97 mole) of tosyl chloride in 220 cm3 of pyridine at 0®C so that the temperature did not exceed 5°C. After the addition, the mixture was maintained at this temperature for lh, then it was poured int© 220 cw5 off ice-cold water with vigorous stirring. After filtration, washing and drying 148.4 g of precipitate were obtained (yield 85%; Rf ~ 0.6 silica/CS^Clj/ acetone/98/2).

NMR spectrum : SH CHS tosyl (singlet 2.4 ppm); 4H CB2N (triplet at 3.4 ppm); 4H CS^O (triplet at 4.1 ppm); 12H aromatics (multiplet between 7.1 and 7.7 ppm). f) Preparation of ,N'a,N,?"tetratosyl-2,s-dimethyl1,4,7,10-tetraazacyclododecane g (0.11 mole) of the compound obtained in d dissolved in 500 cm3 of dry 0HF were added dropwise to 8.8 g (0.22 mole) of a 60% suspension of NaH in oil in 50 car’ of DMF. The addition was carried out at ambient temperature and in such a manner that there was a steady release of hydrogen. After the addition was complete, the mixture was heated to 100°C and a solution of 68.1 g (0.12 mole) of the compound obtained in e dissolved in 500 cm3 of dry DMF was added dropwise. The reaction mixture was then maintained at this temperature for 24h with vigorous stirring.

Th® solvent was then evaporated in a vacuum and the residue was taken up in a CH2C12/H2O mixture. Th® organic phase was washed with water, dried and evaporated to dryness. The residue (100 g) was recrystallised from isopropanol, then from toluene to give, after filtration, washing with isopropyl ether and drying, 36 g of a white solid (yield 40%; Rf = 0.50.6 silica/CS2Cl2/acetone/98/2).

NMR spectrum : 6H CK3 (doublet at X and 1.2 ppm); 12H CHS tosyl (singlet 2.4 ppm); 14H CH2 and CH (multiplet between 3 and 4.5 ppm); 3.6H aromatics (multiplet between 7.1 and 7.7 ppm) . g) Preparation of Ν» Ν', N", N*-tetratosyl-2,6-dimethy1-1, 4,7,10-tetraazacyclododecane (variant).

A freshly prepared solution of sodium ethylate (60 mmole) in 200 ca? of dry DM? was added rapidly to a solution of 17 g (28.7 mmole) of the compound obtained in d in 100 cms of ethanol with reflux. The mixture obtained became clear and was refluxed for l/2h. Th® solvents were then evaporated to dryness, the residue «as taken up in 200 cm3 of DMF and heated to 100®C. A solution of 17 g (30 mmole) of th® compound obtained in jg in 100 car5 of DMF was added to this solution over l/2h. The reaction mixture was maintained at 100°C overnight. The DMF «as then evaporated and the residue was taken up in a H,O/CH,C12 mixture. The product derived from the organic phase was chromatographed on a column of silica with the mixture CH2Cl2/ethyl acetate/98/2 as eluent. The product was recrystallised from isopropyl ether and weighed 13.5 g after drying (yield 58%; Rf = 0.5-0.5 silica/CH2Cl2/acetone/98/2). Spectrum identical to that obtained in f. h) Preparation of 2,6-dimethyl-l,4,7,10-tetraazacyclododecane. g of the compound obtained in f or g were suspended in 80 cm3 of 98% sulphuric acid and heated at 1OO°C in an argon atmosphere for 72h. After being cooled, the reaction mixture was added dropwise to I 1 of ethyl ether at o°c. The 2,6dimethyl-i,4,7,10-tetraazacyclododecane sulphate obtained was filtered off, taken up in water, neutralised with sodium hydroxide, then extracted with CH2C1Z. The organic phases were evaporated to dryness, and the resulting 6 g of solid were used without further purification (yield 75%; Rf = 0.65 alumina/butanol/water/acetic acid/50/25/ιχ).

NMR spectrum (D2O) : 6H CB. (doublet 0.9 to 1 ppm)? 14H CB, and CB (multiplet centred on 2.5 ppm). i) Preparation of 2,6-dimethyl-l,4,7,10-tetraazacyclododecaneN, NS N*-tetraacetic acid.

A mixture of 5.7 g (60 mmole) of aonochloroacetic acid and 3.4 g (60 mmole) of potassium hydroxide in 25 cm4 of water was added to a solution of 3 g (15 mmole) of the compound obtained in ft in 25 cm5 of water. The mixture obtained was brought to <50°C and a solution of potassium hydroxide (3.4 g, so mmole in 25 cs? of water was added so that the pH was maintained between 9 and 10). The addition required Sh. After the addition of potassium hydroxide was complete, heating was maintained for 24h- After cooling, the pH was brought to 2.5 with concentrated HCl. The precipitate formed was filtered off, washed with ice-cold water and weighed 3 g after being dried (yield 35%; Rf - 0.33 ©ilica/ethyl acetate/isopropanol/ ammonia/12/35/30). This compound corresponds to the complex of 2,6-dimethyl-l ,4,7,10-tetraazacyclododecane-N, N', Nw, Nw ' tetraacetic acid with 2 SCI. 9.5 g of this complex were eluted with 200 cm3 of 10% acetic acid from an IRA 958 (OH) ion exchange resin which had been regenerated beforehand with IN NaOH and washed with wafer until it became neutral. The fractions obtained were evaporated to dryness and taken up 3 tines in 50 cm5 of water in order to eliminate traces of acetic acid. The residue obtained was titrated with ethyl ether (100 cm3) to give, after filtration and drying, 6.3 g of white solid, yield: 89%.

NMR spectrum : (D2O) 6H 0¾ (doublet 1.4 and 1.5 ppm); 14Ξ 0¾ and CH (complex multiplet centred on 3.6 ppm); 8H CH, COOH (doublet at 3.8 ppm).

SsaslaJ» Preparation.-, of the..-gadolinium, comolex_of_2., dimethyl-i ,,4., 7, iQrte^gaazac^sladQd^an^L^Lj te^aac^ic^oiiOmetiivialtca^ina.saltl A suspension of S,,425 g (12.54 mmole) of 2,6-dlmethyl1,4,7,10-tetraazacyclododecane-N, N*, N, N'-tetraacetic acid obtained in example 1 ΐ and 2.27 g of Gd2O3 (6.27 mmole) in 125 cm3 C'£ water was heated at 65*C for 24h„ The pH was then adjusted to 7-4 by the addition of aethylglucamine. After determination of free Gd3* by the xylenol orange/EDTA method, 650 mg of 2,6-dimethyl-l, 4,7,10-tetraazacyclododecane- N, Ν', Ν'*, N*-tetraacetic acid (1.5 mmole) were added to complex the remaining gadolinium. The completion of complexation was confirmed by the absence of free Gd5* (determination with xylenol orange) and of free ligands (complexometric determination with Cu2*). The determination off total gadolinium in the solution was carried out by atomic emission spectroscopy in DCP on a Beckmann Spectrospan 4 apparatus. Quantitative yield Rf - 0.49 silica/ethyl acetate/isopropanol/ ammonia/ 12/35/30).

Example 3 : Preparation of 2-hexvl-l,4,7 ,, 10tetraazacyclododecane-N. Nt?f Nm, N***-fcetraacetie acid a) Preparation of N-(2-hydroxyethyl) -N-(2-hexyl-2hydroxyethyl)amine50 g (0.39 mmole) of 1,2-epoxy-octane were added dropwise to 250 cm3 (4 mole) of ethanolamine at 1OO°C. Heating was maintained for Ih after the addition was complete, then the excess ethanolamine was distilled off in a vacuum. The residue was recrvstallised from 600 cm3 of hexane, after filtration and drying. The solid residue obtained weighed 69 g (melting point < 45®C, yield « 93% Rf - 0.62 silica/ butanol/HjO/acetic acid/50/25/11).

NMR spectrum : 3H CH. (triplet 0.9 pom); 10H CHa chain (large singlet at 2.2 ppm); 7H 0¾ and CH (2 poorly resolved aultiplets at 2.® and 3.S ppm) . b) Preparation of N-tosyl-N-(2-tosvloxyethyl)-N-(2-hexyl-2tosyloxyethy1) amine. 47.3 g (0.25 mole) of the compound obtained in & were added in small portions to a solution of 156 g (0.82 mole) of tosyl chloride in 300 of pyridine at over ih. The mixture was maintained at ©°C for 2 days, then it was poured into an ice/HCl mixture (2/1). The product was extracted with CHjC12, then chromatographed on a column of silica with CH2Clg as eluent.., The mass obtained was ns g (yield 72%; Rf = 0.6 silica/CH2cl2/acetone/9S/2).

NMR spectrum : 3H CHj chain (triplet at 0,9 ppm); 10H CH2 chain (large singlet at X.,3 ppm) 9H GHS tosyl (singlet at 2.4 ppm); 4H CHjM (poorly resolved triplet at 3.4 ppm); 3H CKLjO and CH (multiplet at 4.2 ppm); 12H aromatics (multiplet between 7 and 7.1 ppm). c) Preparation of N-tosyl-N-(2~azidO"ethyl)-N-(2"hexyl-2~ azidoethyl)amine. g (0.133 mole) of the compound obtained in b and 29.25 g (0.45 mole) of sodium aside were mixed with 350 cm3 of acetonitrile and 80 cm3 of water. The mixture was heated at S5°C for 3 days. The acetonitrile was then evaporated in a vacuum, the residue was taken up in CH2C12; the organic phase was washed with water, dried and evaporated; 50% of a yellow oil were recovered and used without purification (yield; 95%; Rf = 0.75 silica/CH2Cl2/aceton©/98/2).

NMR spectrum : 3H CHj chain (triplet at 0.9 ppm) ? 10H CH2 chain (multiplet at 1.4 ppm) ; 3H CH3 tosyl (singlet at 2.4 ppm); 5H CH2 and CH (complex multiplet at 3.4 ppm); 4H aromatics (multiplet between 7.1 and 7.7 ppm).

I.R. spectrum N3 - 2100 cm'1 intense. d) Preparation of M-tosy1-M(2-aminoethyl)-N-(2-hexy1-2aminoethyl)amine. g (0.18 mole) of the diazide obtained in c were dissolved in 500 ca? of ethanol to which 5 g of palladium on charcoal at 50% humidity had been added. The suspension was stirred very vigorously under a stream of hydrogen at ambient temperature for 24h. The catalyst was removed by filtration; after evaporation of the ethanol, 61.5 g of diamine were recovered and used without purification (yield: quantitative; Rf « 0.51 silica/MeOH: NH40H/95/5). e) Preparation of N-tosyl-N(2-tosylaminoethyl) -N- (2-hexyl-2tosyl-aminoethyl)amine.

S3.6 g (0.36 mole) of tosyl chloride were added in portions to a solution of 61.5 g (0.1S mole) of the compound obtained in d in 500 ca? of 0¾¾ and 52.5 ca? (0.38 mole) of triethylamine at O°C, After being stirred for 2h at ambient temperature, the reaction mixture was treated with 500 cm3 of water. The organic phase was washed with water, dried, evaporated; the oily residue was chromatographed on & column of silica with CHgClg as eluent. The oil obtained after evaporation of the solvent and taken up in Isopropyl ether gave 60 g of white solid (melting point 120°C; yield 51%; Rf = 0.6 silica/ CH2Cl2/MeoH/98/2) .

NMR spectrum : 13H hexyl chain (poorly resolved multiplet centred at 1 ppm); 9H CHj tosyl (singlet at 2.4 ppm); 7H CE2 and CH (multiplet centred at 3.1 ppm) . f) Preparation of N, Ν', N, N"'-tetratosyl-2-hexyl-l, 4,7,10tetraazacyclododecane A mixture of 46.5 g (71.5 mmole) of th® compound obtained in d above, 41.5 g (73 mmole) of the compound obtained in example 1 e and 24 g (70 mmole) of tetrabutylammonium hydrogen sulphate were suspended in 400 ca? of toluene and 200 cm3 of 20% sodium hydroxide. The mixture was stirred very vigorous at 70°C for 24 h. After cooling, the organic phase was washed with water, dried and evaporated. The residue was crystallised from ethanol, then chromatographed on a column of silica with CHgClg as eluent. 35 g of solid were obtained (melting point 154/161°C). Yield 56%; Rf « 0.55 silica/CH/ CH2Cl2/acetone/98 / 2.

NMR spectrum : 3E CK3 chain (triplet at 0.9 ppm); 10H CH2 chain (multiplet at 1.3 ppm); 12H (3¾ tosyl (singlet at 2.4 ppm); 15H CH2 and CH ring (multiplet at 3.3 ppm); 16H aromatics (multiplet between 7.1 and 7.7 ppm). g) Preparation of 2-hexyl-l,4,7,10-tetraazacyclododecane 12g (13 mmole) of the compound obtained in £ were heated at XCO°C in 40 cm3 of 98% sulphuric acid under argon for 24h.

After being cooled, the mixture was added dropwise to 500 ml of ethyl ether at 0°C. The sulphate obtained was filtered, then neutralised by a 10% solution of sodium hydroxide and extracted with CH2C12. The organic phase was dried over sodium sulphate, then evaporated to dryness to give 2 g of a cream solid (yield; 57%; Rf = 0.75 alumina/hutanol/water/acetic acid/50/25/ll).

The compound was stored in the form of the oxalate by reacting an ethanolic solution of oxalic acid with 2-hexyl-l,4»7»10tetraazacyclododecane overnight at ambient temperature. The oxalate precipitates in th® form of a white solid. h) Preparation of 2-hexyl-l,41,7, lO-tetraasacyclododecane-N, N*» N, N"*-tetraacetic acid.

A solution of 1.09 g (2.8 mmole) of the oxalate obtained in a in 13 cm3 of water and 20 ml of ethanol was neutralised with 470 mg ¢3.4 mmole) of potassium hydroxide. To this solution was added potassium monochloroacetate prepared from 1.063 g (11.25 mmole) of monochloroacetic acid and 630 mg (11.25 mmole) of potassium hydroxide in 20 cm? of water.

The reaction mixture was brought to 60°C and the pH was maintained between 3 and 10 by the addition of potassium hydroxide. The addition requires 3h during which 10 ce5 of water containing 630 mg of potassium hydroxide are added.

After a reaction time of 3h„ 141 mg (1.5 mmole) of chloroacetic acid and 84 mg (1.5 mmole) of potassium hydroxide were added.

The mixture was then held at 60°C for 2 days. After being cooled and acidified to pH 2.5 (6N HCl) the solution was passed through a column of a strongly basic resin IR 958. Slution with 100 cm3 of 10% formic acid yielded 700 mg of product. The flow-through fractions (product not retained) were concentrated and reprocessed on an identical column.

After the same treatment, 2.5 g of product were recovered (yield: 38.4%; Rf = 055 silica/ethanol/buffer/2/1).

NMR spectrum ϊ 3N CH3 chain (triplet 0.9 ppm); 10K CH2 chain (multiplet at 1.4 ppm); 15H CH2 and CH ring (multiplet at 3.3 ppm); 8H CH, COOH (singlet at 3.9 ppm). Spectrum obtained in D,O.

Bx.amole _4 = Preparation of the gadolinium complex of 2-h®xvl~ 1.4.7,10-tetraazacyclododecane-N, Nt Nw, Nw*-tetraacetic acid 488.6 mg (1 mmole) of the compound obtained in example 3 and 181.3 mg (I meg of metal) of gadolinium oxide were suspended in 40 cms of water and heated at 65°C for 2 days. After hours the solution was clear. Th® progress of the complexation was monitored during the reaction by the determination of free gadolinium. When complete, the solution was filtered through a Millipore filter paper, then evaporated to dryness and crystallised from ethyl ether. 550 mg of white solid were thus recovered (yield: 85.5%; Rf = 0.65 EtOH/buffer/2/1).

S£SBBlg_5 = ,lx4^7^^^x^^gxcIoflo 488.6 mg (1 mmole) of the compound obtained in example 3 and 181.3 ag (1 meg of aetal) of gadolinium oxide were suspended in 40 car* of water and brought to 65°C for I2h.

Methylglucamine was added to the clear solution to bring the pH to 7.4. Additions of ligands were made depending on the results of the analyses. The completion of coaplexation was confirmed by the absence of free Gd3* (determination by xylenol ©range) and of free ligands (complexometric determination with copper). The determination of total gadolinium in the solution was carried out by means ©f atomic emission spectroscopy on a Beckman Spectrospan 4 apparatus. Rf = 0.65 in EtOH/buffer/2/1.

Example 6: Preparation of 2-methvl-l,4 tetraagacvclododecane-N, Ν',. H*.· N8*'-tetraacetic acid a) Preparation, of N, N'-di tosyl-1,2-diaminopropane.

In a 1 1 3-necked flask fitted with a magnetic stirrer, a thermometer and a chloride guard tube, 14.8 g of 1,2diaminopropane were dissolved in 500 ml of CH2Cl2 and 58 cm3 of Efc^N. g of tosyl chloride were introduced in portions during l hour» cooling in an ice bath was necessary in order to maintain a temperature of 20°C.

The reaction mixture was then stirred overnight at ambient temperature.

The reaction mixture was transferred to a 1 1 separating funnel and then washed with 2 x 250 cm5 of waterThe organic fraction was dried over Na25O4, evaporated to dryness, then crystallised from isopropyl ether.

Weight obtained = 66 g Yield " 86% Melting point = S3/100°C HMR ppm doublet (3H) 3.1 ppm multiplet (IK) 2.4 ppm singlet (6H) 5-5 ppm exchangeable singlet (2H) 2.9 ppm doublet (2H) 7.1 to 7-8 ppm aromatics (8H) TLC Sio2 eluent CH2C12 90 Rf = 0.75 MeOH 10 b) Preparation of N, N'-ditosvl-bis (2"tosyloxvethyl) ethylene diamine.

In a 500 cm3 3-neckad flask fitted with a thermometer, a chloride guard tube and a magnetic stirrer a solution of 162 g of tosyl chloride in 300 ml of pyridine was cooled to 0°C by means of an ice-salt bath. 29.6 g of bis (2-hydroxyethyl) ethylene diamine were added in portions during 2h at this temperature. At no time must the temperature exceed 5°C. The reaction mixture was stirred for 4h at this temperature, left for 48h at 6/8° C in the refrigerator and then for 4h at ambient temperature.

The reaction mixture was poured into I 1 of ice water and 300 ml of concentrated HCl. The product was extracted with 500 ml of CH2cl2. This organic phase was dried over h’a2S0, , then evaporated to dryness. The residue was taken up in 250 cm3 of ethanol by warming. The product crystallised. It was filtered off on sintered glass and dried at 60°C for 48h.

Weight obtained - 107.5 g Yield « 70% Melting point - 138/14O°C NMR 2.4 ppm singlet (12H) 3.3 ppm singlet + triplet (8H) 4.2 ppm triplet (4H) 7.2 to 7.8 ppm multiplet (16H) TLC SiO2 plate eluent toluene 80 Rf = 0.6 acetone 20 c) Preparation of N, Ν', N, N'-tefcratosyl-2-Biethyl-l,4,7,10tetraazacyclododecane .

In a 1 1 3-necked flask, a solution of 17.5 g of N, N' ditosyldiamino 1,2-propane in 500 sal of dry DMF was stirred for 1/4 hour at ambient temperature. 33 g of Cs2CO3 were powdered and added in suspension to this solution. This suspension is brought to 55°C by means of an oil bath in an inert atmosphere.

A solution of 35 g of N, M*-ditosyl-bis (2-tosyloxethyl) ethylene diamine in 200 cm3 of DMF was added dropwise at this temperature during 2h. After the addition was complete, heating was continued for 48h. The DMF was then removed by distillation in a vacuum. The residue was taken up in a water / CH2C12 mixture.

The organic phase was dried over Ka2SO4. The solvent was removed by distillation in a rotary evaporator.

Th© residue was stirred and heated in 200 ml of ethyl acetate The expected product crystallised. It was filtered off, then dried at 60*C in a vacuum for 24h.

Weight obtained = 22.5 g Yield = 61% Melting point ~ 274/275°C MHS ppm doublet (2H) 2.2 ppm singlet (22H) to 3.8 ppm multiplet (15H) 7.2 to 7.9 ppm multiplet (16H) aromatics TLC SiO2 eluent toluene «80 Rf = 0.56 acetone ~ 20 d) Preparation of 2-»ethyl-l,4,7» 10-tetraazacyclododecane In a 1 1 3-necked flask fitted with a thermometer, an argon bottle and a magnetic stirrer, a solution of 72-5 g of the compound obtained in c) in 300 ml of 98% HjSQ, was heated at 100°C for 48K by means of an oil bath in an inert atmosphere.

The reaction mixture was cooled to ambient temperature and 800 ml of EtgO, cooled to 0°C by means of a bath of ethylene glycol and dry ice, was added during Ih.

The very hygroscopic sulphate precipitated. It was filtered off carefully o»n sintered glass under nitrogen, then quickly dissolved in. 200 ml of water. This solution was made alkaline {pellets of NaOH), then extracted with 5 x 100 ml of CH2C12.

The combined organic phases were dried over Na2SO4, then evaporated to dryness to give is g of very viscous crude product which crystallised on standing.

Yield 90% NMR cdci3 1.x ppm Spectrum in + Dz0 2.7 ppm TI»C A120j plate eluent BuOH ACOSa doublet <2H) singlets as a multiplet (19H, 4 of which are exchangeable) Rf ~ 0.8 25 11 e) Preparation of the complex of 7,10tetraazacyclododecane-N, Ν', Nw, N'-tetraacetic acid with KC1.

In a 250 ml 3-necked flask a solution of 34 g of chloroacetic acid in 150 ca? of water «as cooled to lQeC in an ice bath. g of potassium hydroxide were added at this temperature to neutralise the acid.

The compound obtained in d was then dissolved in this solution- The reaction mixture was then brought to 65®G by means of an oil bath.

A solution of 20 g of KOH in 50 cm3 of water was added cautiously during 6h at this temperature while th© pH was maintained between 8 and 10.

Heating was then continued for 72 hours, then the reaction mixture was acidified to pH = 2.5 with concentrated HCl.

The complex precipitated. It was filtered off onto sintered glass,, rinsed with 50 cm3 of water, then dried at 60°C for I8h in an oven.

Weight obtained = 30 g Yield = 66% Melting point > 30©°C £) Purification of 2-methyl-l,4,7,10~tetraazacyclododecane1,4,7,10-tetraacetic acid. g of the complex obtained in © were suspended in the presence of 15© cm5 of IRA 958 resin, which had been regenerated beforehand.

After dissolution of the complex, this suspension was applied to the head of a column containing 15® ca? of IRA 958 resin.

The elution was carried out with 5% acetic acid solution in water» The fractions containing the expected pure product were evaporated to dryness in order to remove the acetic acid completely.

Weight ©btained =* 18.4 g Yield » 89% Acidity = 100.3% (4 equivalents) titrated with ©.IS NaOH.

TLC SiO2 ©luent EtoAC IsopropanoX nh3, h2o FA3 mass spectrum: Rf = 0.35 mass peak at M + 1 = 419.

SsaffiPle_7: Preparation _ of a solution of ^h©._jgadollMum complex, of 2-aethvl-l,4,7.10-tefcraazacycl.ododecane-rJif, Nwr-tetraacetic acid ίmethylglucamine salt I g (50 mmole) of the compound obtained in example 6 and 9.05 g (25 mmole) of gadolinium oxide were dissolved in 50 ml of twice-distilled water at 70®c. After one hour, dissolution was complete and the pH was close to 3. After cooling, the pH was adjusted to 7.3 with methyglucamine. The solution was adjusted to 100 ml and filtered through a Millipore membrane 0.22 μα. A solution having a Gd content of 0.5 mole/1 was thus obtained. This solution had a viscosity of less than 4 aPa.s. at 2 ©°C (Free Gd not detected).

J&£SSBl£-£= 4 r 7, io-t©t^aaza,z sysla^odecaner^^JlOrtEi&£e£ic_&gi£. a) preparation of N, N*-ditosyl-2,3-diaminopropionic acid.

To a solution of 46 g of sodium hydroxide in 500 ca? of water, 40 g off the monohydrochloride of 2,3-diaminopropionic acid were added with vigorous stirring. 2®0 ca? of ethyl ether were added followed by 110.5 g of tosyl chloride in portions during Ife. Stirring was maintained for 12b, the precipitate forced was filtered off, then washed with water and ethyl ether- The solid obtained was suspended in 1 1 of water, then acidified with 6S HCl. After filtration and washing with water and ethyl ether, the solid was dried for 2 Weight obtained = 76g yield = 65% Melting point = 200-201¾ TLC: SiO2 CH2C12 80/MeOH 20 Rf: 0.5 NMR - 2.4 ppm singlet SB (CH3 of the tosyl group) - 2.8 ppm multiplet 3H (CHj, CH of the diamino chain) - 3.5 to 5 ppm multiplet 3H exchangeable with O2O - 7.2 to 7.8 ppm multiplet OH aromatics. b) Preparation of N, N'-ditosyl-2,3"diaminopropanol.

Xn a 2 1 3-necked flask, a suspension of 40 g of the compound obtained in b) in 600 cm3 of THF was stirred at 20°C in an anhydrous and inert atmosphere (argon).

A solution of 500 ml of IM 0¾ : THF was added in an inert atmosphere during l/2h. The temperature of the reaction mixture rose to 30°C. Stirring was continued for 48h. Hydrolysis was carried out cautiously with 20 ml of water.

The THF was removed by distillation in a vacuum. The residue was extracted with a water/ether mixture. The organic phase «as washed with water, dried over Na2SO4, then evaporated to dryness. The residue was titrated with isopropyl ether until it crystallised. After filtration and drying 35 g of product were obtained.

Yield; 90% Melting point; 126-127°C TLC: SiO, CH2CI2 90/ MeOH 10 Rf: 0.6 NMR - 2.7 ppm - 3 to 3.7 ppm - 6.9 ppm - 7.3 to 7.9 ppm singlet ’’CHg" of tosyl (SH) multiplet (7H, 2 of which are exchangeable) triplet, exchangeable alcoholic OH (IH) multiplet aromatics (8H) c) Preparation of N, Ν', NBS, N'^-tetratosyl-2-hydroxymethyl1,4,7»10-tetraazacyclododecane.

In a 2 1 3-necked flask under argon, 35 g of the compound obtained in b) were dissolved in l 1 of anhydrous DMF, then 58.6 g of anhydrous Cs2CO3 were added.

This suspension was stirred for ih at ambient temperature, then brought to S5°c by means of an oil bath. A solution containing 69 g of N, N'-ditosyl-bis (2-tosyloxyethyl) ethylene diamine In 600 ca? of anhydrous DMF was added dropwise at this temperature during 6h. Heating at 65°C was maintained overnight; the DMF was removed by distillation in a vacuum.

The residue was taken up in a mixture of 400 ml of water and 400 cm? of dichloromethane. The organic phase was decanted, washed with 200 cm? of water, dried over Ma2SO4, then evaporated to dryness. The residual oil was dissolved at 80eC in 200 cm3 of toluene», then kept in a refrigerator for 48h for crystallisation to occur. 24 g of product were obtained.

Yield: 32% Melting point; 143-145°C TLC: SlO2 CH2C12 90/3tOAc 10 Ref: 0»S NMR 2.4 ppm singlet 12H 0¾ tosyl 3.,2 to 4.1 ppm multiplet 17H CH2 ring + CHj-OH 7.2 to 8.1 ppm multiplet 16H aromatics d) Preparation of 2-hydroxymethyl-l, 4,7, lo-tetraazacyclododecane. g of the compound obtained in c) were dissolved in 100 cm3 of 98% H2SO,» This solution was heated to ioo°c for 48h in an inert atmosphere- The reaction mixture was cooled, then added dropwise to 1 1 of ethyl ether cooled by means of a dry ice/acetone bath. The precipitate of the amine sulphate was filtered off onto sintered glass, then washed with ethyl ether. The solid was immediately dissolved in 200 cm3 of water, the solution was adjusted to pH > 12 with NaOH, and evaporated to dryness. After drying th® residual solid in a vacuum in the presence of P2O5, the product was extracted with 2 x 100 cm3 under reflux (THF). Evaporation of the fractions obtained after extraction led to a colourless oil.

Weight obtained: 4.5 g of base Yield: 90% TLF: A12O3 BuOH 50 / Water 25 / AcOH 11 Rf: 0.8 NMR · (CDC13 spectrum) 2.8 ppm singlet (17H) -5- triplet 3...3 ppm exchangeable singlet (5H) e) Preparation of 2-hydroxymethyl-l,4,7,10tetraazacyclododecane-4,7, io-trie.ce~.ic acid.

In a 250 cm3 3-necked flask equipped with a heater-magnetic stirrer, a temperature probe and a pH electrode connected to an analog pH meter and a system for the addition of reagent correlated with the pH of the medium, a solution of 8.5 g of the compound obtained in d), 15.8 g of 2-chloroacetic acid and 100 ml of water were neutralised to pH - 9.5 with the aid of a solution of 15.8 g of potassium hydroxide in 50 5 and applied to a 500 ca3 column of the strongly basic anion exchange resin IRA 958, which had been regenerated beforehand. The alkylation products bonded to the resin. This latter «as rinsed with water, then eluted with fractions of 5% acetic acid. The fractions were evaporated to dryness. The residue was a crude powder which was purified on a preparative HPLC column of diameter 40 loaded with RP-18 - grafted silica.

Weight obtained: 3.5 g of pure product Yield: 22% Melting point: 142-144°C TLC; Sio2 StOAc 12 / Isopropanol 35 / NH4OH 30 Rf: 0.35 Acidity: 198.7% (2 waves) Titration with 0.1 M NaOH - corrected for H2O FAB mass spectrum: peak at H + l = 377 » greparation.of a solution of the gadolinium complex of 2-hydroxymethyl-1,4.7 „ 10-tetraasacvclododecaneA^^ip-tgiacetic acid.

A suspension of 11.05 g of 2-hydroxymethyl-1,4,7,10tetraazacyclododecane 4,7,10-triacetic acid and 5.07 g of gadolinium oxide in twice distilled water was heated at 80°C for ih.

After cooling, the pH was adjusted to 7.3 by the addition of sodium hydroxide and the volume was adjusted to 100 ml. The determination of total gadolinium was carried out by atomic emission spectroscopy (0.28 Ml*'1).

Example..IQ2 greparatipn of 2-hydroxymethyl-l^g7.,J.0r tetraazacyclododecane_il.4.7, lO-tetraaceXic. acid,.

In a 50 ca? reactor equipped with a magnetic stirrer, a solution of 0.7 g of 2-hydroxymethyl-T,4,7fi0tetraazacyclododecane-4,7, XO-fcriacefcic acid and 0-28 g of chloroacetic acid in 2.5 can3 of water was heated at 7Q°C.

The pH was brought to 10.5 by means of a solution of potassium hydroxide and was maintained at this value for 48h at 7Q°C. when the reaction was complete, the pH was brought to 5, then the solution was applied to an IRA 958 resin.

The ligand was chromatographed on th© resin by elution with 5% acetic acid.

After evaporation to dryness, the product is purified by preparative HPLC (RP18 - grafted silica). 0.15 g of ligand were thus recovered in a yield of 18%.

TLC (silica) eluent ethyl acetate 12 Isopropanol 35 Rf = 0.25 NHj, H2O 30 FAB mass spectrum: peak at M + 1 = 435.

Example 11: Preparation of 2-(2rhydroxyetfcv 1) ~1, 10tetraazacvcladodecane-N, N1-. N8B, Μ89-tetraacetic acid. o This ligand was prepared according to the procedure described in examples 8 and 10 for the synthesis of 2-hydroxymethylI, 4,7,10-tetraazacyclododecane-N, N*, N", N*-tetraacetic acid starting from 3,4-diaminobutanoic acid (S. Kasina et al., J. Med Chem., 29, 1933, 1986).

J^pag&tion of 2-metfaylrl 4,7, IQ, 13sgnteaa^eyciopentAdecane-4,7.,.io13-t.etraacetjc acid-ipyodycst A2al_an.d_3rmethylrl^ 4,7, 10, 13.rpentaa.zacvciopentadeca.nex l,A*7,lQ,,1.3-oentaaeet.ic acid (product 12b. a) Preparation of l,4,7,lo,l3-pentatosyl-2-methyl-l,4,7,10,132 o pentaa zacyclopentadecane. .7 g (0.093 mole) of N, N'-ditosy1-1,2-diaminopropane, 75.7 g of caesium carbonate (0.23 mole) and 800 ml of DMF were placed in a 2 1 3-necked flask equipped with a coolant and a mechanical stirrer.

The mixture was placed under argon and heated to 75°C. A solution of S3 g (0.012 mole) of l,ll-mesyloxy-3,6,9tritosyl-3,6,9, triazaundecane synthesised according to Richman and Atkins, Organic Synthesis 58, p. 86, in 700 ml of D.MF was added during 4 hours at 75°C.

The reaction mixture was maintained at 75°C for 48 hours, then filtered and the filtrate was evaporated to dryness.

The residue was taken up in 700 ml of ethanol, the solid was filtered off then taken up in 800 ml of toluene by heating.

Th© solid was filtered off at ambient temperature, then dried at 60°c.

Weight obtained: 45.4 g Yield; 49% Analysis: TLC: SiO2 SO F 254 Merck Eluent CH2C12 / Acetone 98.2 Rf 0.45 Mass spectrum DCI method (NH-) Mass peak at 999. to) Preparation of 2-methyl-l,4,7,10,13-pentaazacyclopentadecane. g (0.044 mole) of the compound obtained in a) were maintained for 72 hours at 1OO°C in 130 ml of concentrated sulphuric acid.

After being cooled, the reaction mixture was poured into a mixture of 250 ml of ethyl ether and 250 ml of ethanol at 0°C.

The solid was filtered off, then dissolved in 250 ml of water and treated with carbon black.

Tne solution was mads alkaline with sodium hydroxide, there extracted with cfi2Cl2.

The organic solution was dried over Na2SO, and evaporated to dryness.

The amine thus obtained can be used as such or in the form of its hydrochloride.

Weight obtained: M = 8.4 g as the free base H = 13.2 g as the 5 HCl Yield: 72.8% Analysis of th© hydrochloride: TLC: A1,O3 F 254 Merck Eluent: Ethanol/Isopropylamine 80/20 Developer: iodine Rf: 0.85 NMR; = 1.7 ppm 3H CH3 = 3.7 ppm 19H CH2 and CH. c) Preparation of 2~methyl~ii,4f,7i, 10,13-pentaazacyclopentadecane-4,7,10,13-tetraacetic acid (product 12a) and 2-methyl-l,4,7,10,13-pentaazacyclopentadecane-l,4,7,10,13pentaacetic acid (product 12b).

In a 500 ml 3-necked flask a solution of 25.7 g (0.27 stole) of chloroacetic acid in 50 ml of water was neutralised to pH « 5 at T < 10°C by seans of 5 M potassium hydroxide. g of the compound obtained in b) (10.043 mmole) dissolved in 20 ml of water was added to this, solution.

The mixture was heated at 55°C and 50 ml of 5 S potassium hydroxide were added during 48 hours to maintain a pH of 8.59.5.

After the addition was complete, heating was maintained overnight.

The reaction mixture was cooled and acidified to pH = 3.

The solution was then applied to 200 ml of DOWEX 50 w resin.

Elution of the resin by means of 1 1 of a 1 M solution of ammonia led to th© recovery of 20 g of crude product.

The crude product was dissolved in 150 ml of water and applied to 250 ml of IRA 958 resin» The resin was washed with water, then eluted with 2 1 of 0.1 M acetic acid, followed by 2 1 of 0.8 M acetic acid. 9 q of crude product 12& were obtained on evaporation of the O.l H acetic acid. 2.5 g of crude product 12b were obtained on evaporation of the 0.3 M acetic acid.

Products 12a and 12b were then purified by preparative HPLC on RP18-siIiea.

Product obtained product 12a : M = 5 g product 12b : M = l.l g Yield: 30% Analysis: TLC: Sio2 60 F 254 Merck Eluent: ethyl acetate/isopropanol/NK3 (30%)/12/35/30 Developer: iodine Product 12a Rf: 0.4 Product 12b Rf: 0.27 Determination of water: Product 12a: KF: 1.8% Product 12b: KF: 2.3% Determination of acidity by means of o.l M NaOH Product 12a: 2 acidity determinations.

Titre: 99.6% Product 12b: 3 acidity determinations Titre: 97.3% FAB mass spectra 12a peak at M + 1 ~ 462 12b peak at M + i - 520

Claims (16)

1. Ligands of formula: o 5 CH COOH Ϊ 5 HOOC — CH - J n\ N- R -2 8 2 HOOC — CH in which 5 R, represents a radical of formula — < CT 2) R — CH — CH — I I R& being selected from a C,-C u alkyl group, a C,-C, hydroxyalkyl group and a C,-C, polyhydroxyalkyl group and a group having th® formula CH-COOH CH«COOH CK-COOH I a. R n being selected from groups A and groups of formula “(CH 2 ) i - Y - A - Y - (CH 2 ) t A being selected from C.,-C 3 alkylene groups, C,-C a hydroxalkylene and C,-Cg polyhydroxyalkylene groups, Y being selected from -C-O- and -0- and t - 1 to 4, II o R ? being selected from a hydrogen atom, a C ? -C u alkyl group, a Cj-C, hydroxyalkyl group and a C,-C 4 polyhy dr oxy alkyl group, m = 0 or 1 which may be identical or different, representing a radical of formula - (CH) p - CH I I Rg R^ Rg and Kj, which may be identical cr different, being selected from a hydrogen atom, a alkyl group, a c,-c 4 hydroxyalkyl group and a C,«C, poiyhydroxyalkyl group, p ~· 1 or 2 n = 0, 1 or 2 and St is selected from a hydrogen atom, a C,“C, alkyl group, a c,~c & hydroxyalkyl group and a c,«c, poiyhydroxyalkyl group, and Z is selected from an oxygen atom and a group having the formula > s R, o being selected from a hydrogen atom, a 0,-C^ alkyl group, a C,-C 4 hydroxy alkyl group, a C»-C, polyhydroxy alkyl group, a group of formula - CH - COOH, Rg % having the meaning given previously, and a group having the formula ' 25 N \ CH-COOH \ CH-COOH Rg 2 being selected from C.,~C 8 alkylene, Ο,-Cg hydroxyaIkylene and C^-Cj polyhydroxyalkylene groups, and their salts. 5 2. Ligands of formula I according to claim 1, in which m is equal to 0. 3. A compound according to claim 1, which is 2,6-dimethyl1,4,7, 10-tetraazacyclododecane-N, N *, N w , N** -tetraacetic acid 4. A compound according to claim 1, which is 2-hexyl10 1,4,7, lO-tetraazacyclododecane-N, Ν', N,N“*-tetraacetic acid. 5. A compound according to claim 1, which is 2-methyX1.4.7.10- tetraazacycXododecane-N,N',N”,N**'-tetraacetic acid. 6. A compound according to claim 1, which is 2-hydroxymethyl1,4,7, l0-tetraasacyclododecane-4,7,10-triacetic acid. 15 7. A compound according to claim 1, which is 2-hydroxymethyl1.4.7.10- tetraazacyclododecane-l ,4,7, ιο-tetraacetic acid. 8. A compound according to claim 1, which is 2-(2hydroxyethy 1 )-1,4,7,10-tetraazacyclododecane-l ,4,7,10fetraacetic acid. 9. A method for preparing a compound according to claim 1 or 5 2, characterised in that a compound of formula X — CH — COOH II I in which R 5 has the meaning indicated in claim 1 and X represents a labile group or an aldehyde of formula Rj -CHO Ha 10 in which Sj has the meaning given in claim 1 is reacted in the presence of hydrocyanic acid or cyanide ions, with a cyclic amine of formula H 8 H in which Rj, Rg, R* and n have the meanings given above ,R', represents a radical of formula —· (CH,), — CH — CK — II Ry 43 R'g being selected from a C,-C u alkyl group, a 0.,-C, hydroxyalkyl group, a C.-C, polyhydroxyalkyl group and a group having the formula f 8 ί ι / J \

2. ’ — S’ - M 2 , H

3. 5 «2- V R 4 , R 7# R 1V b, n having the meanings given in claim l and Z' being selected from an oxygen atom and a group having the formula > M - R-„ R' 1O being selected from a hydrogen atom, a alkyl group,

4. 10 a C„j-C hydroxyalkyl group, a c^-c, polyhydroxyalkyl group and a group having the formula H Et,, Sj, Rj., R,, R. j2 and n having the meanings given above. 10. A method according to claim S, characterised in that the compound of formula III is prepared by reacting a polyamine of formula R' I R'H N -[ - N ] n - R^-NHR IV 5 in which R 1 and Rg have the meanings given in claim 9 and R' represents a tosyl, mesyl or benzene sulphonyl group with a compound of formula X — R 4 — N — R 3 — X V I R f in which R-,, R, and R·· have the meanings given in claim 9 and •j q X represents a labile group.

5. 11. A method according to claim 10, characterised in that the compound of formula III is prepared by reacting a diamine of formula R'HN — R', — NH — R' X -] 5 in which and R r have the meanings given in claim 10, with a compound of formula R' R ? I I X --[ 2¾ -- N J n - % - N - --X XI in which n, Rg, Rj, R 4 and R' have the meanings given in claim 10 and X represents a labile group. 2o

6. 12- Complexes formed by ligands of formula I according to any one of claims l to 8 with metal ions selected from ions of the lanthanides (atomic numbers 57 to 71), ions of the transition metals (atomic numbers 21 to 29) and the ions of metals of 45 atomic numbers 55, 56, 82, 83, and the salts of these complexes with pharmaceutically acceptable mineral or organic bases or basic amino acids.

7. 13. Complexes according to claim 12, in which the metal ion 5 is selected from gadolinium, europium, dysprosium, iron (Fe 3 *) and manganese (Kn 2 *) .

8. 14. A complex according to claim 13 which is the methylglucamine salt of the gadolinium complex of 2,6dimethyl-l,4,7 f 10-tetraazacyclododecane-N,,N’ 10 tetraacetic acid.

9. 15. A complex according to claim 13 which is the methylglucamine salt of the gadolinium complex of 2-hexyl1,4,7,10-tetraazacyclododecane-N, N',N,N™-tetraacetic acid. IS. A complex according to claim 13 which is the j 5 methylglucamine salt of the gadolinium complex of 2-methyl1, 4,7, 10-tetraazacyclododecane-N, N / ,N*,N W/ -tetraacetic acid.

10. 17. A complex according to claim 13 which is th® methylglucamine salt of the gadolinium complex of 2hydroxymethyl-1,4,7,lO-tetraazacyclododecane-4,7,10 triacetic acid. θ

11. 18. A diagnostic composition which can be administered to man, characterised in that it comprises at least one complex according to any one of claims 12 to 17.

12. 19. A composition according to claim 18, comprising a. solution of the complex in an aqueous solvent. -4620. A ligand having the formula I given and defined in claim 1 or a salt thereof, substantially as hereinbefore described and exemplified.

13. 21. A method for preparing a compound having the formula I given and defined in claim 1 or a salt thereof, substantially as hereinbefore described and exemplified.

14. 22. A compound having the formula I given and defined in claim 1 or a salt thereof, whenever prepared by a process claimed in any one of claims 9-11 or claim 21.

15. 23. A oonplex according to claim 12, substantially as hereinbefore described and exemplified.

16. 24. A diagnostic composition according to claim 18, substantially as hereinbefore described.