: "'' CYCLICAL TRIAMINE CHELATING AGENTS The present invention relates to novel cyclic triammine compounds, useful as chelating agents for magnetic resonance imaging, and in other diagnostic and therapeutic applications.Magnetic resonance (MR) is widely used to obtain spatial images of human subjects for clinical diagnosis.A review of this technology and its clinical applications is provided by DP Swanson et al., in 0 Pharmaceuticals in Medical Imaging, 1990, Macmillan Publishing Company, pages 645-681. MR images are a composite of the effects of a number of parameters that are analyzed and combined by computer.The selection of the appropriate parameters in the 5 instruments, such as the radiofrequency (Rf), pulse emission, and distribution of time can be used to intensify or attenuate the signals of any of the parameters that produce an image, improving with this the quality of the image and providing a better anatomical and functional information. In many cases, MR imaging has proven to be a valuable diagnostic tool, since normal tissue and the patient, by virtue of having values of different parameters, can be differentiated in the image. 5 In MR imaging, the in vivo imageREF: 23179 of an organ or tissue is obtained by placing the body of a subject in a strong external magnetic field, sending pulses with radio frequency energy, and observing the effect of the pulses on the magnetic properties of the pro-tones contained in and around the organ or tissue. A number of parameters can be measured. The proton relaxation times, T. and T ~, are of primary importance. T., also called the spin-lattice or longitudinal relaxation time, and T ", also called the spin-spin or transverse relaxation time, depend on the physical and chemical environment of the organ or tissue water, and are measured using techniques of emission of pulses of Rf. This information is analyzed as a function of spatial location by computer, which uses the information to generate an image. Frequently, the image produced lacks an appropriate contrast, for example, between normal and diseased tissue, reducing the effectiveness of the diagnosis. To overcome this disadvantage, contrast agents have been used. Contrast agents are substances that exert an effect on the parameters of the MRI of various chemical species around them. Theoretically, a contrast agent, if preferentially absorbed by a certain portion of an organ or a certain type of tissue, e.g., diseased tissue, can provide an increase in contrast in the resulting images.
In view of the fact that MR images are strongly affected by variations in the parameters of T ... and T, it is desirable to have a contrast agent that affects either or both parameters. The research has focused predominantly on two classes of ragnetic-active materials, that is, paramagnetic materials, which act primarily to decrease T., and superparamagnetic materials, which act primarily to decrease T ". Paramagnetism exists in materials that contain unpaired electrons. Paramagnetic materials are characterized by a weak magnetic susceptibility (response to an applied magnetic field). The paramagnetic materials become weakly magnetic in the presence of a magnetic field, and rapidly lose such activity, that is, they demagnetize, once the external field has been eliminated. It has long been recognized that the addition of paramagnetic solutes to water causes a decrease in the T parameter. Paramagnetic materials, for example, materials containing gadolinium (Gd), have been used as contrast agents for RM, primarily because of its effect on T. The Gd has the highest number of unpaired electrons (seven) in its orbitals 4f, and exhibits the greatest longitudinal relaxivity of any element. A major concern with the use of contrast agents for MR imaging is that many paramagnetic materials exert toxic effects on biological systems, making them unsuitable for in vivo use. For example, the free form of Gd is very toxic. In order to make it suitable for in vivo use, researchers have chelated it with diethylenetriaminepentaacetic acid (ADTP). A formulation of this material that has undergone extensive clinical trials consists of neutralized Gd-ADTP with two equivalents of N-methyl-D-glucamine (meglumine).
This agent has been successful in increasing the contrast of human brain and kidney tumors. Despite its satisfactory relaxability and safety, this formulation has several disadvantages. For example, due to its low molecular weight, the dimeglumine of Gd-ADTP isremoves very quickly from the bloodstream and tissue lesions (tumors). This limits the window of imaging, the number of optimal images that can be taken after each injection, and increases the required doses of agents and relative toxicity. Besides, theThe biodistribution of Gd-ADTP is suboptimal for the imaging of bodily tumors and infections, due to its small molecular size. Several approaches have been taken in attempts to overcome these disadvantages, for example, the Gd and the chelatesof Gd have been chemically conjugated to macromolecule proteins - < such as albumin, polylysines and immunoglobulins. The drawbacks of conjugating ADTP to protein carriers for use in enhancing image contrast in MR imaging include unsuitable biodistribution and toxicity. In addition, proteins provide a defined platform not subject to wide synthetic variation. On the other hand, thermal sterilization of protein conjugates tends to be problematic, especially in the case of albumin conjugates, since the high heat or necessary for sterilization denatures the protein, and can degrade the conjugates. The Patent of E.U.A. No. 5,021,571, published June 4, 1991, given to Mease et al., Discloses cyclohexyl-AEDT (ethylenediaminetetraacetic acid) and its monoanhydride, useful as a chelating agent, which can be bound with an antibody and chelated with a radiometal, to form an immunoconjugateIn view of the drawbacks of other contrast media, it is readily apparent that new and / or better contrast media are needed for MR. The present invention is directed to this, as well as to other important purposes. The present invention provides compounds of the formula: Formula I wherein Z 2 and Z each represent the atoms necessary to complete a monocyclic or polycyclic carbocyclic or heterocyclic ring system, Z 1 and Z 2independently they are optionally substituted n6 n7 with R and R, respectively; R 1, R 2, R 3 and R 4 are independently carboxyalkyl of (C? -C2), - (CH2) n-C (= 0) -NH-R8, or - (CH2) n ~ C (= 0) -0-R8,R is carboxyalkyl (C, -C ™); R and R are independently hydrogen, benzyl, or benzyloxy, benzyl or benzyloxy are optionally substituted with one, two or three substituents selected from the group consisting of amino, isocyanate (-N = C = 0), isothiocyanate (- N = C = S), -NH-C (= 0) -X or -NH-C (= S) -X; Q R is alkyl (C. -C20), - (CH2) -Ar, or polyhydroxyalkyln is 1 0 2; m is from 1 to 15;"X" is a portion directed to a selected target, and Ar is phenyl, optionally substituted with one, two or three substituents selected from the group consisting of amino, acylamino, hydroxy, alkyl (C.-5C-.) , and halogen The compounds of the invention can be chelated with a metal ion and used as contrast agents for magnetic resonance imaging, and for other applications The present invention also provides pharmaceutical compositions comprising a compound of the invention. invention and a pharmaceutically acceptable carrier or diluent The invention further provides methods for providing an image of an internal region of a patient, comprising administering to a patient a compound of the invention, and scanning or scanning the patient, using magnetic resonance imaging, to obtain visible images of the region The present invention is indicated more particularly in the appended claims, and is described in its preferred embodiments in the following description. The present invention provides novel compounds of Formula I, described herein, useful as contrast agents for MR imaging and for other applications described below. The compounds of the invention, when they are chelated with a paramagnetic metal ion to form contrast agents for MR, provide good images of the liver and kidneys, and can also be used to provide images of other organs and / or commons. . In the compounds of Formula I, Z 1 and Z 2 preferably each represent the atoms necessary to complete a monocyclic, bicyclic or tricyclic ring system, and the ring system can be carbocyclic or heterocyclic. As used herein, "carbocyclic" refers to saturated, partially unsaturated and aromatic ani-lysis systems having from 3 to about 10 carbon atoms if it is monocyclic, up to about 20 carbon atoms if it is polycyclic. As it is used herein, polycyclic refers to ring systems containing two or more component rings. The polycyclic ani-lys systems can be fused (ie, they share two or more carbon atoms with at least one other component ring, or they are directly linked by single or double bonds. Examples of monocyclic carbocyclic ring systems include cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, benzene, and cyclohexene A preferred monocyclic carbocyclic ring system is cyclohexane, More preferably, Z 1 and Z 2 each represent the atoms needed to complete a ring system. Cyclohexane Examples of bicyclic carbocyclic ring systems include naphthalene, indene, azulene, biphenyl, biphenylene, and cyclohexylbenzene Examples of tricyclic carbocyclic ring systems include phenanthrene, an-tracene, and indacene.The heterocyclic ring systems contain one or more heteroatoms, or a combination of different heteroatoms, such as 0, N, S, or Si. Suitable monocyclic heterocyclic ring systems include ring systems such as pyridine, furan, thiophene and isoxazole. Examples of bicyclic heterocyclic ring systems include indole, quinoline, chroman and pteridine. Examples of tricyclic heterocyclic ring systems include xanthene, carbazole, acridine and phenorazine. R 1, R 2, R 3 and R 4 preferably are independently 'carboxyalkyl (C. -C 2), ie, - (CH 2) -C (= 0) -0H, wherein p is 1 or 2, more preferably carboxymethyl. In other embodiments of the invention, R, R, R and R can also be independently selected to be the amide or ester of the aforementioned compounds, i.e.
- (CH2) n-C (= 0) -NH-R8, or - (CH2) n-C (-0) -0-R8, wherein R8 is as defined above, n is 1 or 2, preferably 1.
R is carboxyalkyl (C.C.sub.2), preferably carboxymethyl. R and R are independently hydrogen, benzyl or benzyloxy substituted with one, two or three substituents selected from the group consisting of amino, isocyanate (-NC0), isothiocyanate (-NCS), -NH-C (= 0) -X or -NH-C (= S) -X, where X is a portion directed to a selected target. Preferably, R and R are independently hydrogen, substituted benzyl or substituted benzyloxy X can be selected from a wide variety of naturally occurring or synthetically prepared materials, including but not limited to enzymes, amino acids, peptides, polypeptides, proteins, lipoproteins, glycoproteins, lipids, phospholipids, hormones, growth agents, steroids, vitamins, polysaccharides, viruses, protozoa, fungi, parasites, rickettsiae, molds, and components thereof, components of the blood, organ and tissue components, pharmaceutical compounds, haptens, lectins, toxins, nucleic acids (including oligonucleotides), antibodies (monoclonal and polyclonal), anti-antibodies, antibody fragments, anti-gene materials (including proteins and carbohydrates) ), avidin and derivatives thereof, biotin and derivatives thereof, and others known to an expert in t X technique. Is preferably an antibody or antibody fragment. Preferred anti-bodies or fragments include antibodies or antibody fragments capable of directing or bringing the compound of the invention to a tissue at a specific site in the body, for example, those specific for tumor-associated antigens, such as B72.3 , which recognizes colorectal tumors, 9.2.27 and related anti-melanoma antibodies, D612 and related anti-bodies that recognize colorectal tumors, UJ13A and related antibodies, which recognize small cell lung cancer, NRLU-10, NRC0-02 and related antibodies, which recognize small cell lung carcinomas and colorectal tumors (Pan-carcinoma); 7E11C5 and related antibodies, which recognize prostate tumors; CC49 and related antibodies, which recognize colorectal tumors; TNT and related antibodies, which recognize necrotic tissue, PR1A3 and related antibodies, which recognize colon carcinoma; ING-1 and related antibodies, which are described in International Patent Publication W0-A-90/0256;B174, C174 and related antibodies, which recognize squamous cell carcinomas; B43 and related antibodies, which are reactive with certain lymphomas and leukemias; and anti-HLB and related monoclonal antibodies. These particular embodiments of the invention should be particularly useful for the imaging of tumors expressing tumor-specific antigens, or for the radiotherapy of tumors. The portion directed to a selected target can be bound to the compounds by conventional reactions, for example, through the amino, isocyanate or thiocarbonyl groups of the compounds of the invention and of the carboxyl, aldehyde or amino groups which are the antibody or antibody fragment. it can be a straight or branched chain alkyl, saturated or unsaturated, of 1 to 20 carbon atoms, preferably an alkyl of 1 to 10 carbon atoms, more preferably an alkyl of 1 to about 5 carbon atoms. R can also be - (CH?) M-Ar or a polyhydroxyalkyl. Ar is phenyl, optionally substituted with one, two or three substituents selected from the group consisting of amino, acyl-amino (R '-C (= 0) -NH-, wherein R' is alkyl of 1 to 4 carbon atoms , hydroxyalkyl of 1 to 5 carbon atoms and halogen.Preferably, the phenyl is optionally substituted with a substituent.m is an integer from 1 to 15, preferably from 1 to about 10., more preferably from 1 to about 5. The polyhydroxyalkyl (C.CO.sub.0) refers to a straight or branched chain alkyl, saturated or unsaturated, having from 1 to about 20 carbon atoms, preferably from 1 to about 10 carbon atoms, and substituted with 2 or more hydroxyl groups, depending on the length and degree of saturation of the alkyl chain. The R groups can be selected to control the solubility, hydrophilicity and other properties of the compounds of the invention, and can be used to regulate various actions of the chelated compounds with their administration. Such action may include biodistribution of chelates, metabolism, elimination or other biochemical interactions, or lack of them. For example, if you know, selectR is a more lipophilic group, such as a larger alkyl or aryl chain, the resulting compounds would increase the lipid solubility of the prepared contrast media of such compounds, and consequently their biodistribution once administered. The carboxy portion (-C (= 0) -0H) of the carboxy-alkyl groups of R, R, R, R and R may be in the form of an acid anhydride, and such forms are proposed to be literally included within of the term carboxy. A preferred type of anhydride includes the internal anhydrides formed between the carboxy portions of R 1 and R 2, or R 3 and R 4.
Also included within the term carboxy is the form-C (= 0) -0. Salts of the compounds, such as the trifluoroacetic acid salt, or a halogen salt, such as the sodium salt, are also within the scope of the invention. A preferred compound of the invention is dicyclohexylenetriaminepentaacetic acid (ADCTP) (Formula I wherein Z 1 and Z 2 each represent the atoms necessary to form a cyclohexane ring, and R, R, R, R and R are each carboxymethyl). The compounds can be used to form polymeric contrast agents, as described in the published PCT application WO 93/06148. In the published PCT application WO 93/06148, the polynitrile chelating agents are reacted with monomers such as ethylene glycol or polyethylene glycol to form polymers. The polymers formed in this way can then be chelated with a metal ion, and employed as described herein for the compounds of the invention. The compounds of the invention can be substituted by the polynitrile chelating agents described therein to form the polymers. The compounds of the present invention can be produced by a number of generalized methods. The following schemes represent possible methodologies for the preparation of the compounds of the invention, but are not proposed to be limiting, since other methodologies are also possible. In Scheme A, an amine or sulfonamide is used to open two equivalents of an aziridine derivative, to form a symmetrical derivative (Z = Z, R = R), which is subsequently transformed to the final product.
Scheme AY = alkyl, aralkyl or 1) Deprotection of arylsulfonyl nitrogens 2) Conversion of W to R6 (R7) W = R (R) or precursor 3) Alkylation of nitrogens with protected from R (R) L- (CH 9 R = t -butyl, benzyl 4) Removal of RL = leaving group Formula IP = protecting group In Scheme B, a diamine or monopro-tetadine diamine is used to open a derivative of aziridine, to form a symmetric or asymmetric derivative, which is transformed later in the final product.
Scheme BP = Protective group 1) Deprotection of nitrogens R = H or protective group 2) Conversion from W (W ') to R6 (R7)W = R or protected precursor 3) Alkylation of nitrogens of 'R6 with L- (vCH2) n-C0-2R9 W' = R 7 or protected precursor 4) Elimination of R9 7 * from R Formula IL »leaving group 9 R = t-butyl or benzyl In Scheme C, an amine or sulfonamide is used to open epoxide derivatives, to form a dihydroxyamino derivative, which is converted to a triamine, and subsequently transformed to the final product.
Scheme C2) Elimination of Y1) Conversion from W (W ') to R6 (R7) 2) Alkylation of N with L- (CH2) C02R' 9 3) Elimination of R 1 5 Formula IWhen both rings are aromatic, the following methodology of Scheme D may be used 1. In Scheme D, Z2 and Z can be the same or different. twentyScheme D1) conversion of W (W ') to R6 (R7) W = R or a precursor 2) alkylation of nitrogens with - (CH2) nC02Rg protected from R3) elimination of RW' «R or a protected precursor of R Formula IV is iodine or fluorine .9 R is t-butyl or benzyl A preferred embodiment of the invention, dicyclohexylenetriaminepentaacetic acid (ADCTP) (J5) (and the gadolinyl complex (6)) and its isomer ADCTP1 (£ 0 (and the complex (9_) of gadolinium) can be prepared according to the method shown in Scheme I synthetic, which uses the methodology represented in Scheme B.
Scheme I 2? H, SO4ADCTP (5) Complex ADCTP-Gd +3. ' (6)Complex ADCTP'-Gd +3 ())Abbreviations: Ts-p-toluenesulfonyl (tosyl); Py-pyridine; tBu-t-butyl;ATF - trifluoroacetic acid The compounds of the invention can be chelated with metal ions using conventional techniques. For example, an aqueous solution of the compound of the invention can be mixed with the desired metal salt (radionuclide, paramagnetic metal, etc.), usually at a pH from about 4 to about 11, preferably at a pH of about 4. pH from about 5 to about 9. The salt can be any metal salt, preferably a water-soluble salt, such as a halogen salt, or the citrate or nitrate salt. Optionally, buffers such as acetate, phosphate and borate may be added to the aqueous solution to produce the optimum pH for chelation of the compound with the metal ions. The present invention is useful for the imaging of a patient in general, and / or specifically for diagnosing the presence of diseased tissue in a patient. The imaging process of the present invention can be carried out by administering a compound of the invention with a chelated paramagnetic ion (a contrast agent of the invention) to a patient, and then scanning the patient, using the formation of magnetic resonance imaging to obtain visible images of an internal region of a patient and / or of any diseased tissue in the region. By region of a patient, is meant the entire patient or a particular area or portion of the patient. The contrast agents of the invention can be used to provide images of vascular tissue, gastrointestinal tract, liver, kidneys, bladder, and heart, as well as other regions of the body. The patient can be any type of animal, bird, etc., although usually the patient will be a human patient or a species of mammal commonly used in laboratory experiments, such as a dog, rat, or mouse. Examples of paramagnetic ions suitable for use in the present invention for magnetic resonance imaging include the transition elements, lanthanides (rare earths) and actinides, as will be readily apparent to those skilled in the art, in view of the present disclosure . The paramagnetic element can be selected from the elements of atomic number 21-29,43, 44 and 57 to 71. Preferred elements include Cr, i V, Mn, Fe, Co, Ni, Cu, La, Ce, Pr *, Nd, Pm, Sm, Eu, Gd, Tb,Dy, Ho, Er, Tm, Yb, and Lu. More preferably, the elements include Mn, Gd, and Dy, more preferably Gd. The dosages of the contrast agent used according to the method of the present invention will vary according to the precise nature of the contrast agent used. Preferably, however, the dosage should be kept as low as possible to achieve improved contrast imaging, and volumes minimized for IV drip or bolus injection. In this way, potential toxicity is minimized. For most MR contrast agents, the appropriate dosage will usually be in the range of from about 0.005 to about 5.0 millimoles of paramagnetic metal / kg body weight, preferably from about 0.01 to about 1.0 millimoles of metal paramagnetic / kg body weight, more preferably from about 0.025 to about 0.2 millimoles of paramagnetic metal / kg body weight. It is reasonably within the experience of the average physician in this field to determine the optimal dosage for any MR contrast agent by relatively routine experimentation, both in vivo and in vitro. The administration can be carried out in various ways, such as intravascularly, orally, rectally, etc., using a variety of dosage forms. The useful dosing that will be administered, and the particular mode of administration will vary depending on the age, weight and the particular mammal and region that are to be explored. Typically, the dosage is initiated at lower levels, and is increased until the improvement in the desired contrast is achieved. By means of a general guide, the amounts described above can be used, taking into consideration the chelating agent and any portion directed to a selected target, although larger and smaller amounts can be used. Various combinations of chelating agents and paramagnetic ions can be used to modify the relaxation behavior of the contrast agent. In carrying out the method of the present invention, the contrast medium can be used alone, or in combination with other diagnostic, therapeutic or other agents. The magnetic resonance imaging techniques that are employed in the methods of the invention are conventional and are described, for example, in DM Kean and MA Smith, Magnetic Resonance Imaging: Principles and Applications, (William and Wilkins, Baltiraore, 1986 ) and Swanson et al., supra. The FIRM techniques included include, but are not limited to, nuclear magnetic resonance (NMR) and electronic spin resonance (REE). The preferred modality of imaging is NMR. In addition to their use in MR imaging, the compounds of the invention can be used to bind displacement reagents (eg Dy (III), or relaxation agents (eg Gd (III), as well as mixtures thereof (for example Dy (III) with Gd (III), and thus have applications in magnetic resonance spectroscopy.
The compounds of the invention are also useful as contrast agents for x-rays and ultrasound, for nuclear medicine as imaging agents, and for radiotherapy, and administration is carried out as described above. For x-rays and ultrasound, the compounds can be used to chelate heavy metals such as Hf, La, Yb, Dy, Gd and Pb. For nuclear medicine, the compounds can be used to chelate radioactive metals, in particular the radioisotopes of Se, Fe, Pb, Ga, Y, Bi, Mn, Cu, Cr, Zn, Ge, Mo, Te , Ru, In, Sn, Sr, Sm, Lu, Sb, W, Re, Po, Ta, and TI. Preferred radionuclides include 44cSr, 64Cu, 67Cu, 111 I.n, 212-P.b, 68rGa, 87vY, 90"Y, 153Scm, 212BBi. , -e- > 99m_Tc, 177.Lu, 186DRe, and 188DRe. MMas pref.eri..b.lemen_te, el. rad, i.o- nuclide is 90Y. These radioisotopes can be atomic or preferably ionic. For use as local radiation sensitizers for radiation therapy, the compounds may chelate or radioactive metals such as those described above, and optionally a variety of heavy metals and lanthanide metals (rare earths) as described above. In this respect, the selection of heavy metals and G-ras lands can be made to match the spectrum of aberration. 5 energy of the incident radiation, and increase the conversion of the Auger electrons, high energy particles and the emission of secondary radiation. For use in fluorescence spectroscopy, and as a marker in assays such as immunoassays, or the compounds of the invention can chelate a fluorescent metal ion, selected from metals of atomic number from 57 to 71. Ions of the following are preferred. metals: The, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu. Eu is a preferred fluorescent metal ion. In addition, the compounds of the invention can be used to treat poisoning with heavy metals, for example, for poisoning with iron, arsenic or lead. For the treatment of heavy metal poisoning, the compounds will usually be administered alone, without chelated ions, although as will be recognized by one skilled in the art, in some applications of the treatment of metal poisoning, some calcium or other metal ions may be added to the formulation of the compounds before their administration. Otherwise, the administration can be carried out as described above. The compounds of the invention can be used to treat the poisoning of metal ions such as Mg, Ca, Se, Ti, V, c_? Mn, Mg, Fe, Eu, Er, Pb, Co, Ni, Cu, Zn, Ga, Sr, Y, Zr, Te,Ru, In, Hf, W, Re, Os, Pb, Bi, Dy, Mn, Gd, Hf, La, Yb, Te, In and As. Additionally, the compounds of the invention can be chelated to a metal, and used as therapeutic agents for treating metal deficiencies, and administration is carried out as defined above. The metal ions that can be bound to the compounds for the treatment of deficiency include Mn, Fe, Zn, Co, Ni, Cu, Cr, Mg, Se andCa. The pharmaceutical compositions of the invention can be formulated, for use as contrast agents or for another use as those described herein, with the compounds of the invention and conventional pharmaceutical or veterinary carriers or diluents, and can also contain other conventional agents, such as, for example, stabilizers, antioxidants, agents for osmolality adjustment, buffering agents, pH adjusting agents, etc. Depending on the particular particular use, the pharmaceutical compositions can be formulated with the compound of the invention in chelated or non-chelated form. For some uses, it may be preferable to supply the pharmaceutical compositions with the compound of the invention in non-chelated form, and to add the metal ion to the pharmaceutical composition just prior to its current use, allowing time for the metal ion to chelate with the compound of the invention. The pharmaceutical compositions may be in a form suitable for injection or infusion directly, or after their dispersion or in dilution with a physiologically acceptable carrier medium, for example water for injection. Thus, the pharmaceutical compositions can be formulated in conventional administration forms, such as powders, solutions, suspensions, dispersions, etc., however solutions, suspensions and dispersions in physiologically acceptable carrier medium will generally be preferred. The pharmaceutical compositions can be formulated for administration using physio-logically acceptable carriers or excipients, in a manner totally within the skill of the art. For example, the compounds, optionally with the addition of pharmaceutically acceptable excipients, can be suspended or dissolved in an aqueous medium, and the resulting solution or suspension is then sterilized. Forms that can be administered parenterally, for example intravenous solutions, must, of course, be sterile and free of physiologically unacceptable agents, and must have a low osmolality, to minimize irritation or other adverse effects from administration, and thus the Contrast should preferably be isotonic or slightly hypertonic. Suitable carriers include aqueous vehicles ordinarily used to administer parenteral solutions, such as Sodium Chloride Injection, Ringer's Injection, Dextrose Injection, Dextrose Injection and Sodium Chloride, Lactated Ringer's Injection and other solutions, such as those described in the Remington 'Pharmaceutical Sciences, 15th ed., Easton: Mack Publishing Co., pages 1405-1412 and 1461-1487 (1975) and in The National Formulary XIV, 14th ed. , Washington: American Pharmaceutical Association (1975). The solutions may contain preservatives, antimicrobial agents, buffers and antioxidants conventionally used for parenteral solutions, excipients and other additives that are compatible with the contrast agents, and which will not interfere with the manufacture, storage or use of the products. The present invention is further described in the following examples, which are not intended in any way to limit the scope of the invention. EXAMPLES Example 1 - Synthesis of Dicyclohexylenetriaminepentaacetic acid (ADCTP) (_5) A. Trans-2-N-tosylamide cyclohexyl tosylate (1_): To a stirred suspension of trans-2-amino-cyclohexanol hydrochloride (75 g , 0.49 moles, Aldrich Chemical Co., Milwaukee, Wisconsin) in anhydrous pyridine at 0 ° C was added 200 g (1.05 moles) of p-toluenesulfonyl chloride. The resulting mixture was stirred at room temperature for 48 hours, and then poured into ice (1000 g). After stirring for 2 hours, a yellow solid was filtered and washed with water (2 x 500 ml) and ethanol (200 ml). The solid was dried under vacuum for 24 hours to give 1_ as a slightly yellow solid (192 g, 92%); p.f. 160-162 ° C; 1 H NMR (360 MHz, CDC13) d: 7.70 (d, 4 H, J-7.9, Ar-H), 7.30 (d, 2 H, J = 7.9, Ar-H), 7.23 (d, 2 H , J - 7.9, Ar-H), 4.98 (d, 1 H, J-5.6, NH), 4.24 (m, 1 H, CH-0), 3.12 (m, 1 H, CH-N), 2.43 ( s, 3 H, CH 3), 2.39 (s, 3 H, CH 3), 2.12-1.18 (m, 8 H); 13 C NMR (300 MHz, CDC13)? : 145.60, 143.88, 137.97, 130.45, 130.18, 128.44, 127.76, 81.48, 55.65, 32.32, 31.10, 23.32; HRMS (PK pairing, LSIMS, CH2Cl2-MeOH) calculated for C22H25N05S2 (M + H) 424.12524, found (M + H) 424.12353. Elemental Analysis calculated for C22H25N ° 5S2"H2 °: C '56'76, H' 5-85I N> 3.01, found, C, 56.82, H, 6.00, N, 3.29 B. N-Tosyl cyclohexyl aziridine (2) ): To a suspension of sodium hydride (20 g, 0.833 moles) in dry tetrahydrofuran (THF) (500 ml) was added trans-2-N-to-silamide cyclohexyl tosylate 1 (190 g, 0.449 moles) in portions at room temperature After evolution of hydrogen ceased, the mixture was filtered, and the precipitate was washed with THF.The combined organic liquor was evaporated to give 2. as a yellow solid (105.5 g, 94%), mp 59 -61 ° C; XH NMR (360 MHz, CDC13) $: 7.68 (d ", 2 H, J-8.2, Ar-H), 7.28(d, 2 H, J = 8.2, Ar-H), 2.92 (d, 2 H, J = 1.0, CH-N), 2.39 (s, 3 H, CH3), 1.74 (m, 4 H, CH2) , 1.35 (m, 2 H, CH2), 1.18 (m, 2 H, CH2); 13 C NMR (300 MHz, CDC13): 144.58, 130.12, 128.09, 40.31, 23.30, 22.10, 19.94; HRMS (PK pairing, LSIMS, CH2Cl2 ~ Me0H) calculated for C13H17N02S (M + H) + 252.10583, found (M + H) + 252.10592 Calculated Elemental Analysis for Cj-H.-NO ^, C, 62.12; H, 6.82; N, 5.57; Found, C, 61.90; H, 6.90; N, 5.62. C. Di- (N-trans-2'-aminocyclohexyl) amine (J3_A and 3J3): To a refluxing solution of (±) -trans-1,2-diaminocyclohexane (100 ml, 0.833 mol) in anhydrous acetonitrile (200 mi) 35 g (0.139 mol) of N-tosyl cyclohexyl aziridine _2 in acetonitrile (50 ml) were added slowly. After the addition was complete, the solution was heated to reflux for 2 hours. The solvent was removed, and the excess trans-1,2-diaminocyclohexane was distilled under vacuum. The resulting oil was titrated with hexane to give a pale yellow solid.(43 g, 84 Z), which was used in the next step without further purification. The above solid (43 g) was heated at 100-110 ° C with 98% concentrated H2SO4 (200 ml) for 20 hours. The resulting solution was cooled with an ice-salt bath, and ether was added slowly with stirring, to keep the temperature below 10 ° C. More ether was added, until which no further precipitation occurred. The precipitate was filtered and washed with ether under nitrogen. The gray solid was redissolved in a small amount of water (10 ml), and concentrated sodium hydroxide (60%) was added to make the solution basic. The basic aqueous solution was extracted with ether (5 x 100 mL). Drying and evaporation of the ether solution provided a mixture of 3J3 and A as a pale yellow solid. The mixture was separated by flash chromatography (CH2C12 / CH30H saturated with NH3 (g): 7/3) to give compound JA, 9.0 g (31%) and compound 3B, 2.5 g (9%); 3A, p.f. 104-106 ° C; H-NMR (360 MHz, CDC13)? : 2.26 (m, 1 H), 2.24 (m, 2 H), 1.95 (m, 1 H), 1.63 (m, 3 H), 1.39 (m, 5 H), 1.23-1.06 (m, 6 H) , 0.90-0.83 (m, 2 H); 13 C NMR (300 MHz, CDC13) $ 60.64, 55.97, 36.87, 32.79, 25.86; HRMS (P-pairing, LSIMS, CH 2 Cl 2 -MeOH) calculated for C 12 H 25 3 (M + H) + 212.21267, found (M + H) + 212.21181; 3B, p.f. 56-58 ° C; 1 H NMR (360 MHz, CDC13) or: 2.21 (m, 2 H), 1.96 (m, 2 H), 1.80 (m, 4 H), 1.51 (m, 6 H), 1.09-0.85 (m, 6 H); 13 C NMR (300 MHz, CDC13) S: 64.59, 57.49, 35.40, 34.93, 26.19, 25.51; HRMS (PK pairing, LSIMS, CH2Cl2-Me0H) calculated for C? 2H25N3 (M + H) 212.21267, found (M + H) + 212.21282. D. T-Butyl Dichloclohexylenetriaminepentaacetic acid(t-butyl ADCTP) (4 ^): A mixture of dicyclohexentriaraine 3A (18.5 g, 87.6 mmol), t-butyl bromoacetate (100 ml, 615 mmol), anhydrous potassium carbonate (67 g, 613 or mmoles) , and molecular sieves (4 A, 60 g), in anhydrous acetonitrile (500 ml) were stirred at 50 ° C for 35 hours. The precipitate was removed by filtration, and the solution was evaporated under vacuum to remove the solvent and excess t-butyl bromoacetate. The resulting oil was dissolved in isopropyl alcohol, and the solution was maintained at -18 ° C to -20 ° C. After 2 days, white crystals were collected and washed with isopropanol, to give 15.8 g of 4; the mother liquor was cooled to -20 ° C and after 1 week, a second crop of 4 (15.7 g) was obtained. Total: 31.5 g (46%); p.f.106-107.5 ° C; NMR of 1 n (360 MHz, CDC13) S: 3.50-3.61 (m, 10 H), 2.71 (m, 2 H, CH-N), 2.54 (m, 2 H, CH-N), 2.04 (m, 4 H), 1.61 (m, 4 H), 1.46 (s, 49 H, CH 3), 1.19-1.05 (m, 8 H); 13 C NMR (300 MHz, CDC13) S: 173.96, 172.47, 80.59, 80.17, 65.73, 64.31, 54.05, 47.58, 31.98, 29.81, 28.75, 26.47; EMAR (PK pairing, LSIMS, CH2Cl2-Me0H) calculated for C42H72N2 ° 10 (M + H) + 782.55307, found (M + H) + 782.55664. E. Dicyclohexylenetriaminepentaacetic acid (ADCTP) (5_): _4 (15.0 g, 19 mmol) in trifluoroacetic acid (ATF) (20 ral) was stirred for 15 hours. The ATF was evaporated and dried under vacuum to give an oil, which was titrated with hexane to give a white solid (15.3 g). The elemental analysis of this crude product showed that it contained approximately 2 to 3The equivalent of ATF. Purification of the crude product was carried out according to the following procedure: the crude product (1.5 g) in water (3 ml) was neutralized with saturated Ba (0H) 2 to pH 8, and heated for 30 minutes. The slurry was filtered and washed with water. The precipitate was suspended in water (5 ml), and the pH was adjusted to 2 with H2SO, at 20%. The suspension was stirred at 80 ° C overnight (adjusted to pH 2 with dilute aqueous barium hydroxide / sulfuric acid).
The precipitate was filtered, and the aqueous filtrate was evaporated and dried to give _5 as a white solid (0.75 g,80%). p.f. 170 ° C (decomposition); H NMR (360 MHz,DMS0-do,) £: 3.78 (d, 1 H, J = 48.6, N-CH-CO), 3.73 (d, 1 H, J = 48.6, N-CH-CO), 3.62 (d, 4 H, J = 41.8, N-CH-CO), 3.56 (d, 4 H, J = 41.8, NCH-CO), 3.17 (m, 2 H), 2.87 (m, 2 H), 2.33 (m, 2 H) , 1.61 (m, 4 H), 1.31-1.12 (m, 8 H); 13 C NMR ('360 MHz, DMS0-d6): 178.46, 176.17, 71.40, 69.03, 53.32, 34.66, 32.61, 32.55, 30.35. ERAR (P-pairing, LSIMS, MeOH / DMSO) calculated for C2 H35N3010 (M + H) + 502.24007, found (M + H) + 502.24077; Elemental Analysis calculated for C22H35N3 ° 10 • H2 °: C '50-86; H, 7.18, N, 8.09; Found: C, 51.29; H, 7.12, N, 8.12. Example 2 - ADCTP Gadoline Complex (6_): 3 g of the above crude crude product (ADCTP (_5) -alpha of ATF) were dissolved in isopropanol (10 ml) and saturated with anhydrous ammonia (excess) by bubbling ammonia anhydrous through the solution for 15 minutes. The resulting white precipitate was filtered and washed with isopropanol. The white powder obtained (3.1 g) was dissolved in deionized water (5 ml). Gadoline nitrate (2.5 g) in deionized water (5 ml) was added slowly to the above aqueous solution. The reaction was monitored by the PAR test (monosodium salt of 4- (2-pyridyl-azo) resorcinol). The addition of gadolinium nitrate was stopped 3+ when the PAR reagent indicated the presence of non-chelated Gd. After the addition, the solution was adjusted to pH 7 with ammonium hydroxide / nitric acid. Acetone was added until the solution became cloudy, and the suspension was cooled to 4 ° C. After 2 days, the resulting white precipitate was filtered and washed with acetone. The white solid (6) was dried at 80 ° C under vacuum for 2 days, to give a pale yellow solid (3.10 g, 71%); p.f. 220 ° C (decomposition). The Elemental Analysis calculated for C ^ H ^ QN-O .. nGd .3H "0: C, 35.52; H, 5.96; N, 9.41; Gd, 21.14; found: C, 35.41; H, 6.04; N, 9.16; Gd, 20.98. Example 3 - Synthesis of Isomer of Dicyclohexylenetriaminepentaacetic acid (ADCTP ') (8) A. t-Butyl ADCTP' (): A mixture of dicyclohexylene-triamine 3_B (7.8 g, 37 mmol), t-butyl bromoacetate ( 40 ml, 246 mmol), potassium carbonate (25.5 g), mesh or molecular (4 A, 20 g) in anhydrous acetonitrile was stirred at 50 ° C for 2 days. The same procedure used in the synthesis of the t-butyl ADCTP ^ in Example 1, Part D above gave 7_ as a white solid (22 g, 76%); p.f. 107-109 ° C. 1 E NMR (360 MHz, CDC13) S: 3.64-3.51 (m, 10 H, CH 2), 2.75 (m, 2 H), 2.57 (m, 2 H), 2.08 (m, 4 H), 1.63 (m, 4 H), 1.47, 1.45 (2 s, 49 H, CH 3), 1.23-1.08 (m, 8 H); 13 C NMR (300 MHz, CDC13): 172.86, 170.28, 66.23, 63.23, 47.96, 29.04, 27.10, 27.03, 25.05, 24.89. HRMS (PK pairing, LSIMS, CH2Cl2-MeOH) calculated for C42H72N2 ° 10 (M + H) + 782.545307, found (M + H) + 782.54987. B. ADCTP '(8.): Following the same procedure used in the synthesis of the ADCT0 (5_) in Example 1, Part E above, the ADCTP' 8 was synthesized in 80? of yield, p.f. 178 ° C; NMR of H (360 MHz, DMS0-d6)? : 3.76 (d, 1 H, J = 65.1), '3.71 (d, 1 H, J - 65.8), 3.61 (d, 4 H, 44.5), 3.56 (d.4 H, J - 44.5), 3.15 (d. m, 2 H), 2.86 (m, 2 H), 2.30 (m, 2 H), 2.09 (i, 2 H), 1.61 (m, 4 H), 1.30-1.08 (m); 13 C NMR (DMS0-d6) S: 172.92, 170.17, 68.22, 63.203, -5 46.97, 28.27, 26.77, 24.90, 24.66; HRMS (PK pairing, LSIMS, MeOH / DMSO) calculated for C22H35N3 ° 10 (M + H) + 502.24007, found (M + H) + 502.23841; Elemental Analysis Calculated for C22H35N5 ° 10: C '52-67¡H »7- ° 3; N, 8.33; found: C, 52.48; H, 7.01; N, 8.33. 0 Example 4 - ADCTP Gadolíneo Complex '(9): The gadolinium complex of ADCTP' (^) was prepared using the procedure of Example 2 above; p.f. 230 ° C 'l (decomposition). Example 5 - Imaging Studies with the complexof ADCTP Gadolíneo (6) The ADCTP gadolinium complex (6_) of Example 2 was used in studies of magnetic resonance imaging of rabbits. The gadolinium complex of ADCTP (6) was studied in three doses (10, 30 and 100 micromoles per kg), using magnetic resonance sequences heavily loaded in TI (TR 400, TE 12 mSeg) in 1.5 T. Experiments were performed with a rabbit in each dose. Each rabbit was anesthetized during imaging, and the imaging periods were before administration of > , fifteenminutes, 30 minutes, 60 minutes and 24 hours after the administration of (6_). For liver imaging, at 10 JiM / kg, the visual and quantitative improvement was not clear. However, at 30 JbM / kg, the visual and quantitative improvement of the liver contrast was satisfactory. At 100 JuM / kg, the visual and quantitative improvement of the liver was also satisfactory. The elimination of b_ from the liver is complete at 24 hours. Imaging of the kidney and spinal cortex showed a similar result, but with a dose of 10 jiM / kg of 6 a less desirable result was produced than with doses of 30 μM / kg or 100 JbM / kg.
It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.
Having described the invention as above, property is claimed as contained in the following: