WO2002059097A1

WO2002059097A1 - Novel gd(iii) ligands with bi- and bis-azolic structures

Info

Publication number: WO2002059097A1
Application number: PCT/ES2002/000031
Authority: WO
Inventors: Paloma BALLESTEROS GARCÍA; Sebastián Cerdán García-Esteller
Original assignee: Laboratorios Farmaceuticos Rovi, S.A.
Priority date: 2001-01-25
Filing date: 2002-01-24
Publication date: 2002-08-01
Also published as: ES2172461A1; ES2172461B1

Abstract

The invention relates to 1) a compound having general formula A, wherein radicals R1, R2, R3 and R4 have the values that are universally known in the organic chemistry formulation, and which can be used in the preparation of chelates that are used as contrast agents in imaging diagnosis; 2) the compound in claim 1, wherein X in formula A is (CH2)n; 3) the compound in claim 2, wherein n is 0; 4) the compound in claim 2, wherein n is 1; 5) the compound in claim 1, wherein X in formula A is CH2OCH2; 6) the compound in claim 1, wherein X in formula A is CH2NHCH2; 7) a method for obtaining the general formula A compound from claim 1, which is characterised in that a biazole is made to react with 1,2-dibromoethane in the presence of BTBA and sodium hydroxide in order to obtain the corresponding alkyl derivative, which is subsequently made to react with methyl iminodiacetate, thereby synthesising the corresponding methyl derivative which in turn reacts with sodium hydroxide in the presence of water, in order to produce the desired sodium salt; 8) a method for obtaining the general formula A compound from claim 1, which is characterised in that two 1-chloroethyl-3,5-dimethylprazol molecules are made to react with paraformaldehyde in an acid medium and the reaction mixture is subsequently heated in the presence of chlorohydric acid in order to obtain the corresponding bispyrazole which, in turn, is made to react with methyl iminodiacetate in order to obtain the corresponding intermediary methyl compound, whose hydrolysis in a basic medium produces the desired sodium salt; 9) the complexes of the compounds in claim 1 with transition metals and lanthanides; 10) the complexes in claim 9, wherein the metal to be chelated is gadolinium; 11) the complexes in claim 9, wherein the metal to be chelated is dysprosium; 12) the clinical use in imaging diagnosis of the compounds in claim 1 and the corresponding complexes thereof.

Description

NEW G1 (III) LINES WITH BI-Y STRUCTURE

B1S-AZOL1CA

D E S C R I P C I O N

TECHNICAL FIELD OF THE INVENTION

The synthesis of complexones of General Formula A is proposed, which is indicated below,

Formula A

in order to obtain a new series of contrast agents for Magnetic Resonance, with relaxation properties superior to those currently available in the market.

STATE OF THE PREVIOUS TECHNIQUE

Currently, the contrast of Magnetic Resonance Imaging (MRI) is induced, in 90% of cases, using lanthanide chelates. Most ligand structures used contain aminoacetic acid or iminodiacetic acid units (complexones).

SUBSTITUTE SHEET (RULE 26) So far mixed ligands have been synthesized that include groups of

Minodiacctics and azilic rings (hydrocyclic complexones), capable of forming tetradentate complexes with Gd (III). These keels have relaxation properties analogous or superior to the commercial complexes currently used as contrast agents in diagnostic imaging.

However, the stability constant for Gd (IlI) in the compounds studied so far is not high enough to allow its use in clinical settings. For this reason, we believe that the introduction of new complexation sites would allow this problem to be overcome, obtaining a new series of contrast agents whose efficacy should be greater than those currently available. This fact would reduce the dose of contrast agent administered while maintaining the final intensity of the contrast obtained.

DETAILED DESCRIPTION OF THE INVENTION

Within this new line we propose the synthesis of complexones that have the general formula Formula A indicated below,

(CH ^ n n = 0 or 1

CH ₂ OCH ₂

CH ₂ NHCH ₂

Formula A

By way of example, and without it being understood that they limit in any way the scope of the present invention, the present specification describes the synthesis of the following complexones:

SUBSTITUTE SHEET (RULE 26) Synthesized complexones

Ri = R2 = R3 = 4 = Me, n = 0

R ₂ = R ₄ = C ₆ H ₄ -N0 ₂ -p, n = 1

SUBSTITUTE SHEET (RULE 26)

Precursor biazoles of complexones 1, 2 and 3

5 6 7

Complexones 1, 2 and 3 have been synthesized from 5, 6 and 7 according to the following reaction scheme (scheme 1):

SUBSTITUTE SHEET (RULE 26)

Scheme 1

Finally, complexone 4 has been obtained starting from I-cIoroethyl-3,5-dimethylprazole (8). The coupling of two units of 8 with paraformaldehyde in acidic medium leads to 9. Heating of 9 in medium HC1 conc. leads to bispyrazole 10, which by reaction with methyl iminodiacetate gives rise to 11. Finally, the basic hydrolysis of 11, as in the previous cases, leads to complexone = 4 (scheme 2).

SUBSTITUTE SHEET (RULE 26)

Scheme 2

1. Synthesis of ^2,2, 2 ", 2" - [(3,3'-4,4'-b¡p¡razoI difeniI-l, l'-d¡iI) bis (nitrile etiIen- )] sodium tetrakisacetate (1)

1.1. Alkylation of 5 with dibromoethane. Synthesis of l, l'-b¡s (2-bromoethyl) - 3,3'-diphenyl-4,4'-bipyrazole (12a), l, l ^, -bis (2-bromoethyl) -3 ₁ 5 ^, - diphen¡l-4,4'- bipyrazole (12b) and l, r-bis (2-bromoethyl) -5,5'-dιfen ¿1-4, '-bipyrazole (12c).

In the alkylation reaction of 5, using 1,2-dibromoethane under the experimental conditions described below, the three possible regioisomers (12a-c) have been isolated as depicted in scheme 3.

SUBSTITUTE SHEET (RULE 26)

Scheme 3

A mixture of 2.2 g (7.69 mmol) of 5.92 g (23.07 mmol) of NaOH, 62 mg (0.19 mmol) of BTBA, 23.13 g (123.04 mmol) of 1,2-dibromoethane and 1.5 mL of H ₂ O is heated at reflux for 1 h and 30 min. Then, it is allowed to cool, 50 mL of H ₂ O are added, extracted with CH2CI2 and the organic phase obtained is dried over anhydrous M Sθ ₄ . The desiccant is removed by filtration and the solvent under reduced pressure. The reaction crude is subjected to column chromatography on silica gel, using as eluent a CH2CI2 / MeOH mixture (98: 2). In order of elution, 1.17 g (30%) of 12a are obtained as a white solid (mp 137-39 ° C, EtOH), 0.69 g (18%) of 12b as a yellow oil and 0, 25 g (6%) of 12c as a white solid (mp 170-75 ° C, CH2Cl ₂ / Hexane). l, l'-Bis (2-bromoethyl) -3.3 ^, -diphenyl-4.4'-bioirazole fl2a):

IR (KBr): v 1600, 1515, 1510, 1440, 1415, 1350, 1320, 1270, 1180, 950, 775,

720, 695 cm- '.

"H-NMR (200 MHz, CDCI3): δ 7.61-7.48 (4 H, m, aromatic), 7.28 (2 H, m,

H ₅ ), 7.25-7.16 (6 H, m, aromatic), 4.46 (4 H, t, J = 6.2 Hz, CH ₂ -N (Azol)), 3.74

(4 H, t, J = 6.2 Hz, CH ₂ -Br) pp.

^IJ CR N (100 MHz, CDCI ₃ ): δ 150.6, 133.2, 131, 5, 128.2, 127.5, 1 10.6, 53.6,

SUBSTITUTE SHEET (RULE 26) 30.4 pp.

Elemental analysis for C22H2 _θ Br2N4: theoretical: 52.81% C; 4.04% H; 1.20% experimental N: - 53.03% C; 4.23% H; 11.08% N

l '-Bisr2-bromoethyl) -3.5 ^, -diphenyl-4.4 ^t -bipyrazole fl2b):

IR (KBr): l495, 1445, 1305, 1215, 940, 760, 700 was " ¹ .

'H-NMR (200 MHz, CDC): δ 7.45 (1 H, s, H ₃ ), 7.44-7.38 (2 H, m, aromatic),

7.31 (6 H, m, aromatic), 7.13-7.08 (3 H, m, aromatic and H ₅ ), 4.36 (2 H, t, J = 6.4 Hz, CH2-N (AzoI-H ₅ )), 4.35 (2 H, t, J = 6.8 Hz, C / ₂ -N (Azol-H ₃ )), 3.67 (2 H, t, J = 6, 8 Hz, BrCH ₂ CH ₂ -N (Azol-H ₃ )), 3.65 (2 H, t, J = 6.4 Hz, BrCH2CH ₂ -

N (Azol-H ₅ )) ppm.

> ³ C-NMR (100 MHz, CDC1 ₃ ): δ 150.6, 143.6, 141.5, 139.7, 133.3, 130.6, 129.9,

129.3, 128.6, 128.1, 127.7, 127.4, 112.2, 110.6, 53.4, 50.3, 30.3, 29.7 ppm. Lr-Bisf2-bromoethyl) -5,5'-diphenyl-4.4 ^t -bipyrazoI (12c):

IR (KBr): v 1485, 1440, 1395, 1325, 1285, 1230, 970, 935, 860, 790, 750, 700,

630 cπr ¹ .

^J H-NMR (200 MHz, CDCI3): δ 7.33-7.21 (8 H, m, aromatic and H ₃ ), 7.03-6.99 (4

H, m, aromatic), 4.23 (4 H, t, J = 6.9 Hz, CH ₂ -N (Azol)), 3.56 (4 H, t, J = 6.9 Hz, CH ₂ -Br) ppm.

^I3 C-NMR (100 MHz, CDCI3): δ 140.8, 138.7, 129.9, 129.6, 128.7, 128.6, 112.2,

50.1, 29.3 ppm.

1.2. Synthesis 2 ^ ', 2 ^,, ^2, "- ^[(3,3, ^{diphenyl-4,4,} -bipirazol-l, ^l, -diiI) bis (etilennitri- Io)] tetrakisacetato methyl] (13)

A mixture of 1 g (2 mmol) of 12a and 1.29 g (8 mmol) of methyl iminodiacetate is heated at 10 ° C for 8 h and 15 min. Then it is allowed to cool

SUBSTITUTE SHEET (RULE 26) and 50 mL of CH2CI2 are added. The white solid formed (NH (CH2C02Me) 2-HBr) is filtered and washed with CH2CI2. Then, the solvent is removed under reduced pressure and the reaction crude is subjected to column chromatography on silica gel, using as eluent a CH2CI2 / 5 MeOH mixture (98: 2). 0.84 g (65%) of 13 are obtained as a colorless oil. IR (KBr): 1 1750, 1450, 1210, 1 190.1 160 cm " ¹ .

«H-NMR (200 MHz, CDCI3): δ 7.52-7.47 (4 H, m, aromatic), 7.34 (2 H, s, H ₅ ), 7.20-7.13 (6 H, m, aromatic), 4.20 (4 H, t, J = 6.2 Hz, CH ₂ -N (Azol)), 3.61 (12 H, s, CH3), 3.45 (8 H , s, CH ₂ -CO ₂ Me), 3.22 (4 H, t, J = 6.2 Hz, CH ₂ -N) ppm. 0 "C-NMR (100 MHz, CDCI3): δ 171.6, 149.7, 133.6, 131.7, 128.1, 127.3, 127.2,

110.8, 55.6, 54.9, 51.7, 51.5 ppm.

Elemental analysis for C34_H ₄ oN6θg ^• 2H6N6O14 (13-2 picric): theoretical: 49.47% C; 4.16% H; 15.05% experimental N: 50.08% C; 4.54% H; 14.58% N 5 1. Synthesis of 2 ^ '2 ^, % 2'"- [(3,3 ^, -diphenyl-4,4 ^, -bipyrazol-l, l'-diyl) bis (ethylenitrile)] sodium tetrakisacetate (1) A mixture of 800 mg (1.21 mmol) of 13, 194 mg (4.85 mmol) of NaOH and 32.5 mL of H2O (MQ) is kept under stirring at room temperature for 48 h, then the reaction mixture is heated at 54 ° C 0 for 5 h. Allow to cool and the aqueous phase is washed with CH2CI2. Then the H ₂ O is removed under reduced pressure and the solid obtained is dried under vacuum. 772 mg (92%) of 1 as a white solid IR (KBr): v2150, 1575, 1405 cπr ¹ .

'H-NMR (200 MHz, D ₂ O): δ 7.62 (2 H, s, H ₅ ), 7.12 (10 H, wide s, aromatic), 5.20 (4 H, t, CH ₂ -N (Azol)), 3.12 (8 H, s, CH ₂ -CO ₂ Na), 3.01 (4 H, t, CH ₂ -N) ppm.

¹³ C-NMR (100 MHz, D ₂ O): δ 177.4, 149.4, 131.8, 131.3, 127.4, 126.9, 126.6, 109.6, 57.5, 53.4, 48.8, 48.6 ppm.

2. Synthesis of Σ ^^^^ - KS ^ S.S etrametiM ^ '- bipir zol-l.r- ° diyl) bis (ethylene nitrile)) sodium tetrakisacetate (2)

2.1. Synthesis of l, l'-bis (2-bromoethyl) -3,3 ', 5,5'-tetramethyl-4,4'-bipyrazole (14)

In the alkylation reaction of 6, using 1,2-dibromoethane under the ⁵ experimental conditions described below, the

SUBSTITUTE SHEET (RULE 26) two possible alropymomers 1 ab as shown in scheme 4.

14 a-b

Scheme 4 A mixture of 0.96 g (5.05 mmol) of 0.6 0.6 g (15.2 mmol) of NaOH, 40 mg (0.26 mmol) of BTBA, 15.03 g (80.4 mmol) of 1,2-dibromoethane and 1.5 mL of H2O is heated at reflux for 1 h. It is then allowed to cool, 50 mL of H ₂ O are added, extracted with CH2CI2 and the organic phase obtained is allowed to dry over anhydrous MgSÜ ₄ . The desiccant is removed by filtration and the solvent under reduced pressure. The reaction crude is subjected to column chromatography on silica gel using as eluent a CH2CI ₂ / MeOH mixture (98: 2). In order of elution, 0.22 g (11%, yellow solid (mp 112-14 ° C, Hexane); major isomer) and 0.15 g (8%, yellow oil; minor isomer) of 14a and 14b 14 to:

IR (KBr): and 1735, 1620, 1540, 1500, 1460, 1435, 1400, 1310, 1270, 1130, 955, 900, 825, 720, 40 cm- ¹ .

• H-NMR (400 MHz, CDCI3): δ 4.27 (4 H, t, J = 6, 7 Hz, CH ₂ -N (Azol)), 3.62, (4 H, t, J = 6 , 7 Hz, CH ₂ -Br), 1.98 (6 H, s, CH ₃ ), 1.93 (6 H, s, CH ₃ ) ppm. "C-NMR (100 MHz, CDCI3): δ 147.6, 137.6, 109.7, 49.6, 30.2, 11, 9, 9.7 ppm. MS m / z (%): 404 (M ⁺ , 36), 296 (15), 229 (14), 190 (100), 107 (29) Elemental analysis for C] H2θBr2N4: theoretical: 41.60% C; 5.00% H; 13, 86% N experimental: 42.08% C; 5.1 1% H; 13.77% N

14b:

'll-RIVIN (200 MHz, CDCI3): δ 4.42 (4 H, t, J = 6, 4 Hz, CM ₂ -N (Azol)), 3.76, (4

SUBSTITUTE SHEET (RULE 26) H, t, J = 6.5 Hz, CH ₂ -Br), 2.15 (6 H, s, CH ₃ ), 1.98 (3 H, s, CH ₃ ), 1, 93 (3 H, s,

CH3) ppm.

2.2. Synthesis of ^2,2, 2 ", 2"'- ^[(3,3,, 5,5'-tetramethyl-4,4'-bipyrazol-l, r- diyl) bis (etilennitrilo)] tetrakisacetato methyl ( fifteen)

A mixture of 0.31 g (0.76 mmol) of 14a and 0.39 g (3.03 mmol) of methyl iminodiacetate is heated at 110 ° C for 2 h. Then, it is allowed to cool and 50 mL of CH2CI2 are added. The white solid formed (H (CH2Cθ2Me) 2-HBr) was filtered and washed with CH ₂ O2. Then, the solvent is removed under reduced pressure and the reaction crude is subjected to column chromatography on silica gel, using an AcOEt / Hexane mixture (1: 1) as eluent. 0.22 g (51%) of 15 are obtained as a colorless oil. IR (film): v 1735, 1420, 1200, 1020, 745 cπr ¹ .

• H-NMR (400 MHz, CDCI3): δ 4.08 (4 H, t, J = 6.7 Hz, CH ₂ -N (Azol)), 3.61 (12 H, s, CH ₃ -O ), 3.41 (8 H, s, CH ₂ C02Me), 3.09 (4 H, t, J = 6.7 Hz, CH ₂ -N), 2.00 (6 H, s, CH ₃ ) , 1.95 (6 H, s, CH3) ppm. "C-NMR (100 MHz, CDCI3): δ 171.5, 147.1, 138.0, 110.0, 55.5, 54.5, 51.5, 48.4, 12.2, 9, 8 ppm

MS m / z (%): 564 (M ⁺ , 20), 187 (68), 174 (100), 146 (54), 128 (91).

2.3. Synthesis of 2 \ 2 ", 2"'-[(3,3', 5,5 etraιnetil-4,4 ^, -bipirazol-l, l'-diyl) bis (ethylene nitrile)] sodium tetrakisacetate (2) A mixture of 800 mg (1.4 mmol) of 15, 224 mg (5.6 mmol) of NaOH and

38 mL of HO (MQ) is kept under stirring at room temperature for 72 h. Then, the aqueous phase is washed with CH2CI2 and then the H ₂ O is removed under reduced pressure. The solid obtained is dried under vacuum. 768 mg (90%) of 2 are obtained as a white solid. IR (KBr): v / 1590, 1310 cm- '.

SUBSTITUTE SHEET (RULE 26) ¹ H-NMR (400 MHz, D ₂ O): δ 3.93 (4 H, t, J = 7.5 Hz, CH ₂ -N (Λzol)), 2.91, (8 H, s, CI I ₂ CO ₂ Na), 2.68 (4 H, t J = 7.5 Hz, CH ₂ -N), 1, 77 (6 11, s, CH ₃ ), 1, 69 (6 H, s, CH3) ppm.

^I C-NMR (100 MHz, D ₂ O): δ 180.4 149.2, 141, 2, 1 1 1.2, 60.4, 53.3, 48.2, 12.7, 10.8 ppm

3. Synthesis of ^2,2, 2 ", 2 '" - [(3,3'-bis (4-nilrofcnil) ^-4,4, -mctilenb¡spirazol- l, l'-diyl) bis (etilennitrilo) ) sodium tetrakisacetafo (3) 3.1. Synthesis of 4,4'-methylene-bis (5- (4-πitrophenyl) -lH-pyrazole) (7)

A mixture of 4.53 g (30 mmol) of 7-nitrobenzaldehyde, 1.82 g (16 mmol) of 2-methoxy-2,3-dihydro-4 // - pyran, 2mL of AcOΗ, 3 mL of Η2O and 2 drops of piperidine is heated at reflux for 24 h. The aqueous supernatant phase is then decanted and the solvent is removed under reduced pressure. The reaction crude is subjected to column chromatography on silica gel, using as a eluent a Hexane / AcOEt mixture (85: 15) obtaining 1.02 g (19%) of 16 as a white solid (E, E: E isomers , Z).

E £ isomer;

• H-NMR (200 MHz, CDCI ₃ ): δ 9.50 (2 H, s, CHO), 8.24 (4 H, d, J = 8.8 Hz, AA'XX 'aromatic system), 7 , 53 (4 H, d, J = 8.8 Hz, AA'XX "aromatic system), 7.33 (2 H, s, CH = C), 3.73 (2 H, s, CH ₂ ) ppm Isomer EJ.

'H-NMR (200 MHz, CDCI3): δ 9.86 (1 H, s, CHO), 9.74 (1 H, s, CHO), 8.32 (2 H, d, J = 8.8 Hz, AA'XX 'aromatic system), 8.24 (2 H, d, J- 8.8 Hz, AA'XX ^* aromatic system), 7.68-7.60 (4 H, 2 d, AA system 'XX' aromatics), 7.44 (1 H, s, CH = C), 7.40 (1 H, s, CH = C), 3.66 (2 H, s, CH ₂ ) ppm.

MeOH 1.53 g (4.18 mmol) of aldehyde 16 (mixture of isomers E, E; E, Z) is added and the reaction mixture is heated at reflux for 1 h and 30 min. It is then allowed to cool and the solid formed is filtered. 1.71 g (58%) of 17 are obtained as a yellow solid (single E.Z isomer).

SUBSTITUTE SHEET (RULE 26)

⁵ • H-NMR (200 MHz, DMSO-d ₆ ): δ 8.15 (4 H, d, J = 7.6 Hz, AA'XX 'aromatic system), 8.10 (2 H, d, J = 7.6 Hz, aromatic AA'XX 'system), 7.91 (1 H, s, CH = C), 7.73 (1 H, s, CH = C), 7.69 (2 H, d , J = 8.2 Hz, AA'XX ¹ aromatic system), 7.48-7.40 (4 H, 2 d, AA'XX 'aromatic system), 7.32 (2 H, d, J = 8 , 3 Hz, aromatic AA'XX 'system), 7.17 (1 H, s, CH = N), 7.13-7.06 (4 H, 2 d, aromatic AA'XX' system), 6 , 31 (1 H, s, CH = N), 3.48 (2 H, s, CH ₂ ), 2.26 (3 H, s, CH ₃ ), 2.09 (3 H, s, CH ₃ ) ppm.

A mixture of 3.17 g (4.51 mmol) of 17, 1.1 g (20.3 mmol) of MeONa and 7 mL of triethylene glycol is heated at 100 ° C for 2h. Then, the reaction crude is allowed to cool and poured onto H2θ-ice and 3 mL of AcOH. ⁵ the solid formed is filtered and washed with a saturated NaHCO ₃ solution and then with _H2O then dissolved in MeOH and the solvent is removed under reduced pressure. 0.56 g (33%) of 7 are obtained as a brown solid (1.2 g of polymeric material are isolated). • H-NMR (400 MHz, DMSO-d ₆ ): δ 8.21 (4 H, d, J = 8.8 Hz, AA'XX '0 aromatic system), 7.87 (4 H, d, J = 8.8 Hz, aromatic AA'XX 'system), 7.46 (2 H, s, H ₃ ), 4.09 (2H, s, CH ₂ ) ppm.

3.2. Synthesis 4,4'-methylene-bis [l- (2-bromoethyl) -3- (4-nitrophenyl) pyrazole] (18)

A mixture of 575 mg (1.47 mmol) of 176.7 mg (4.41 mmol) of NaOH, 12 mg (0.037 mmol) of BTBA, 2 mL (23.52 mmol) of 1,2-dibromoethane and 0 , 5 mL of H ₂ O is heated at reflux for 2 h. Then let it cool, it

SUBSTITUTE SHEET (RULE 26) add 10 L of H ₂ O, is extracted with CH CI? and the organic phase obtained is allowed to dry over anhydrous M Sθ ₄ . The desiccant is removed by filtration and the solvent under reduced pressure. The reaction crude is subjected to column chromatography on silica gel, using as a eluent a Hexaηo / AcOEt mixture (1: 1). 1115 mg (13%) of 18 are obtained as a white solid. On the other hand, 64 mg of a compound that could be identified as 4,4'-methylene-bis [l- (2- bromoethyl) -5- (4-nitrophenyl) pyrazole] and 13 mg that could correspond 4, 4 ^* - methylene-3,5'-bis (4-niüOphenyl) -bis [l- (2-bromoethyl) p'razoI] whose purification was not possible. 'H-NMR (400 MHz, CDCI ₃ ): δ 8.23 (4 H, d, J = 8.9 Hz, aromatic system AA'XX'), 7.80 (4 H, d, J = 6, 0 Hz, aromatic system AA'XX ', 7.28 (2 H, s, H ₅ ), 4.49 (4 H, t, J = 6 Hz, CH ₂ -N (Azol)), 3.76 (4 H, t, J = 6.0 Hz, CH ₂ -Br) ppm. 3.3. Synthesis of 2,2 ^, ^ ", 2" ^ [(3 ^ ^, -bis (4-n¡trophenol) -4,4 ^» -methylenebizpyrazol-l, l'-diiI) bis (ethylene nitrium)] methyl tetrakisacetate (19)

A mixture of 33 mg (0.055 mmol) of 18 and 39 mg (0.24 mmol) of methyl iminodiacetate is heated at 110 ° C for 5 h. Then, it is allowed to cool and 10 mL of CH2CI ₂ are added. The white solid formed (NH (CH2Cθ2Me) 2-HBr) is filtered and washed with CH2CI2. Then, the solvent is removed under reduced pressure and the reaction crude is subjected to column chromatography on silica gel, using as eluent a CH2CI ₂ / EtOH mixture (99: 1). 28 mg (67%) of 19 are obtained as a yellow oil. ¹ H-NMR (200 MHz, CDCI3): δ 8.21 (4 H, d, J = 8.9 Hz, AA'XX 'aromatic system), 7.79 (4 H, d, J = 8.7 Hz, aromatic AA'XX system), 7.38 (2 H, s, H ₅ ), 4.22 (4 H, t, CH ₂ -N (Azol)), 4.02 (2 H, s, CH ₂ ), 3.66 (12 H, s, OCH ₃ ), 3.46 (8 H, s, CH7CO ₂ CH3), 3.22 (4 H, t, CH ₂ -Br) ppm.

SUBSTITUTE SHEET (RULE 26) 3.4. Synthesis of ^2,2, 2 ", 2" - | (3,3'-bis (4-nitrophenyl) -4,4'-mctilcnbispirazol-

I, r-diyl) bis (cthylenitrile)) (sodium ctrakisacetate (3)

A mixture of 28 mg (0.037 mmol) of 19.6 mg (0.148 mmol) of NaOH and 1 mL of H ₂ O (MQ) is heated at 60 ° C for 31 h. Allow to cool, 2 mL of H ₂ O (MQ) are added and the aqueous phase is washed with CH2CI2. The HO is then removed under reduced pressure and the solid obtained is dried under vacuum. 23 mg (78%) of 3 are obtained as a yellow solid.

• H-NMR (200 MHz, D ₂ O): δ 8.06 (4 H, d, J * 8.7 Hz, aromatic AA'XX 'system), 7.52 (2 H, s, H ₅ ) , 7.39 (4 H, d, J = 8.7 Hz, aromatic AA'XX system), 4.11 (4 H, t, CH ₂ -N (Azol)), 3.98 (2 H, s , CH ₂ ), 3.08 (8 H, s, CH ₂ Cθ2Na), 2.84, (4 H, t, CH ₂ N) ppm.

4. Synthesis of 2 _I 2% 2 ", 2 ^, " - | (3 ', 5,5 etrametiI-4,4 ^, -methylenebispyrazol- l, l'-diyl) bis (ethylenitriIo)] sodium tetrakisacetate (4)

4.1. Synthesis of l- (2-chloroethyl) -4-hydroxymethyl-3,5-dimethylpyrazol (9) At a solution of 1.0 g (6.3 mmol) of 8 and 0.23 g of paraformaldehyde in 5 mL of 1 , 2-dichloroethane is passed a gaseous stream of HC1 for 2 h. Then, the reaction mixture is heated at reflux for 2 h. Next, 5 L of HC1 ce and 25 L of H2O are added. The reaction mixture is neutralized with Na ₂ C 3, extracted with CH ₂ CI ₂ and the organic phase is allowed to dry over MgSO ₄ - The desiccant is removed by filtration and the solvent under reduced pressure. The reaction crude is purified by recrystallization to obtain 763 mg (67%) of 9 as a white solid (mp 95-7 ° C, CH ₂ Cl ₂ Hexane). 'H-NMR (400 MHz, CDCI3): δ 4.47 (2 H, wide s, CH ₂ O), 4.25 (2 H, t, J = 6.4 Hz, CH ₂ -N (AzoI) ), 3.84 (2 H, t, J = 6.3 Hz, CH ₂ C1), 2.28 (3 H, s, CH ₃ ), 2.24 (3 H, s, CH3) ppm.

4.2. Synthesis of 4,4'-methylene-bis [l- (2-coroethyl) -3,5-dimethipyrazol] (10) A suspension of 990 mg (5.25 mmol) of alcohol 9 in 0.5 mL of HCI ce it is heated at reflux for 1 h. It is then allowed to cool and 10 mL of H2O are added and the reaction mixture is neutralized with Na ₂ C03. It is extracted with CH ₂ CI ₂ and the organic phase is allowed to dry over MgSO 4. The desiccant is removed by filtration and the solvent under reduced pressure. 680 mg (79%) of 10 a white solid are obtained (mp 99-101 ° C, CH ₂ CI ₂ / Hexane).

• H-NMR (200 MHz, CDCI ₃ ): δ 4.23 (4 H, t, J = 6.2 Hz, CH ₂ -N), 3.80 (4 H, t, J = 6.2 Hz , CH ₂ CI), 3.39 (2 H, s, CH ₂ ), 2, 10 (6 H, s, CH ₃ ), 2.03 (6 H, s, CH3) ppm.

SUBSTITUTE SHEET (RULE 26) 16

4.3 Synthesis of 2,2 \ 2 '\ 2 " ^, - | (3,3 \ 5,5'-tctramct¡l-4,4'-mct¡lcnb¡sp¡razol-

], r-dii!) bis (ctilcnnitrílo) methyl jfctrakisacctato (I I)

A mixture of 340 mg (1.03 mmol) of 10 and 733 mg (4.55 mmol) of methyl iminodiacetate is heated at 10 ° C for 24 h. Then it is left

5 cool and 10 mL of CH2CI2 are added. The white solid formed is filtered

(NH (CH ₂ CO ₂ Me) ₂ HBr) and washed with CH ₂ C1 ₂ . The solvent is then removed under reduced pressure and the reaction crude is subjected to column chromatography on silica gel, using a CH2O2 / EtQH mixture as eluent.

(98: 2). 118 mg (20%) of 11 are obtained as a yellow oil. or • H-NMR (200 MHz, CDCI3): δ 3.95 (4 H, t, J = 6.5 Hz, CH ₂ -N (AzoI)), 3.57 (12

H, s, OCH3), 3.41 (8 H, s, CH ₂ CO ₂ Me), 3.27 (2 H, s, CH ₂ ), 2.90 (4 H, t, J = 6.6 Hz, CH ₂ -N), 2.05 (6 H, s, CH3), 1.86 (6 H, s, CH ₃ ) ppm.

4.4. Synthesis of ^2,2, 2 \ 2 "- [(3,3% ^{5,5'-tetramethyl-4,4,} -met¡lenbisp¡razol- 5 l, l'-diyl) bis (etilennitriIo) ] sodium tetrakisacetate (4)

A mixture of 81 mg (0.14 mmol) of 11, 22.5 mg (0.56 mmol) of NaOH and 3 mL of H ₂ O (MQ) is kept under stirring at room temperature for 18 h. 2 mL of H ₂ O (MQ) are added and the aqueous phase is washed with CH ₂ CI ₂ . The H2O is then removed under reduced pressure and the solid obtained is dried under 0 vacuum. 80 mg (94%) of 4 are obtained as a white solid.

'H-NMR (200 MHz, D ₂ O): δ 4.02. (4 H, t, J = 7.4 Hz, CH ₂ -N (Azol)), 3.36 (2 H, s, CH ₂ ), 3.14 (8 H, s, CH ₂ CO ₂ Na), 2.79 (4 H, t, J = 7.3 Hz, CH ₂ -N), 2.05 (6 H s, CH3 ), 1.84 (6 H, s, CH3) ppm.

5. Spectrophotometric studies of chelation with Gd (IH)

Spectrophotometric chelation studies of different complexones 1-4 and EDTA with Gd (III) have been carried out from which the apparent affinity constants (' _af ) of complexones with Gd (III) can be calculated. A Molecular Devices SPECTRA Mac 340 PC microplate spectrophotometer has been used, measuring the absorbance of the ArsenazoIII metallochromic indicator at a wavelength λ = 680 nm.

The determinations are based on the monitoring of the variation of the concentration of ArsIlI-Gd (III) complex (ε = 1, 1 x 10 ⁴ M ^'1 ) present in the medium, in titrations with Gd (IIl) carried out in presence and absence of complexone. the measurements were made in 96-well microplates at a

SUBSTITUTE SHEET (RULE 26) temperature of 25 "C. The experimental conditions were chosen based on those described by Scarpa. Different solutions of 0.1 mM Arslll, 100 mM NH ₄ CI and 20 mM Hepes (final pH - 6.7) were prepared. they were carried out by adding increasing amounts of GdCIj until reaching a final concentration of Gd (III) 300 μM. The values obtained are:

6. Determination of relajativities

The relaxation times of water protons have been determined by Η NMR (25 ° C, pH = 7) at 8.74 Teslas, on a Bruker AM-360 spectrometer. T, has been determined using the following inversion-recovery sequence:

. Dl-180 ^or -τ-90 ° -Aq

T ₂ has been measured with the Carr-Purcell-Maiboom-Gill sequence: Dl-90 ° (PHl) - [t-180 ° (PH2) - τ] „- Aq

In both cases at least 13 different values of τ were used. With each sample three measurements of Ti or T _{2 were made} .

The procedure that followed was to prepare solutions of compounds 1-4 and 5 M EDTA, 100 mM Tris / HCl, 155 M NaCl, in the absence and presence of 0.5 mM Gd (III) in the case of complexones 1 -4, and 5 mM Gd (III) for EDTA.

The values of relaxivity Rj and R ₂ were calculated according to the expression:

Δ 1 / T, ₍₂₎

^R l (2) ~ [M]

where Δ l / T ^ is the difference between the relaxation times measured in the absence and presence of Gd (III), and [M] is the molar concentration of the metal used in the determination.

SUBSTITUTE SHEET (RULE 26) In the following table, the values of relaxivity obtained in the different determinations are collected.

SUBSTITUTE SHEET (RULE 26)

Claims

1.- A compound of General Formula A

FORMULA A

where the radicals R |, R ₂ , R3 and R, have the values universally known in the formulation of organic chemistry; which can be used for the preparation of chelates useful as contrast agents in diagnostic imaging.

2. The compound of Claim 1, wherein X in the Formula

A is (CH ₂ ) _n .

3. The compound of Claim 2, wherein n is 0.

4. The compound of Claim 2, wherein n is 1.

5. The compound of Claim 1, wherein X in the Formula

6. The compound of Claim 1, wherein X in the Formula

A is CH ₂ NHCH ₂ .

7. A process for obtaining the compound of General Formula A, of Claim 1, characterized in that a biazole is reacted with 1,2-dibromoethane in the presence of BTBA and sodium hydroxide, to obtain its corresponding alkylated derivative , which is subsequently done

SUBSTITUTE SHEET (RULE 26) react with methyl iminodiacetate, synthesizing the corresponding methyl ester which in turn reacts with sodium hydroxide in the presence of water, to achieve the desired sodium salt.

8. A process for obtaining the compound of General Formula A, of Claim 1, characterized in that 1-cIoroethyl-3,5-dimethyliprazole is reacted with paraformaldehyde in an acid medium, the reaction mixture is then heated, in the presence of hydrochloric acid, to obtain the corresponding bispyrazole, which, in turn, is reacted with methyl iminodiacetate to obtain the corresponding methyl ester compound, whose hydrolysis in basic medium gives the desired sodium salt.

9. The complexes of the compounds of Claim 1 with transition metals and lanthanides.

10. The complexes of Claim 9, wherein the metal to be complexed is Gadolinium.

11. The complexes of Claim 9, wherein the metal to be complexed is the Disprosium.

12.- The clinical use of the compounds of Claim 1 and their corresponding complexes, in diagnostic imaging.

SUBSTITUTE SHEET (RULE 26)