TWI651097B - Method for preparing contrast agent precursor - Google Patents

Abstract

The invention provides a preparation method of a contrast agent precursor, which comprises the steps of: taking one or two tert-butyl a 2,2'-(1,4,7-triazacyclononane-1,4-diyl) diacetic acid, phenyl bromoacetate and a basic compound are co-dissolved in an anhydrous acetonitrile and subjected to a a bimolecular nucleophilic substitution reaction to obtain a product; the product is dissolved in water to obtain a solution; and the solution is adjusted to adjust its pH value. When the solution is acidic, diethyl ether is added to remove the ether. A first organic layer is adjusted to be basic, and the diethyl ether is added to obtain a second organic layer containing one of the organic solvents, and the second organic layer is the final product.

Description

Method for preparing contrast agent precursor

The present invention relates to a method for preparing a contrast agent precursor, in particular to a preparation comprising di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl-(1,4, A contrast agent precursor of the structure of 7-triazacyclononane)-1,4-diyl]} diacetic acid.

Molecular imaging is a non-invasive technique for observing changes and molecular transformation processes in tissues or cells in vivo, including magnetic resonance imaging (MRI) and nuclear medicine imaging, among which nuclear medicine imaging technology Can be divided into positron computed tomography (PET) and single photon computed tomography (SPECT).

Compared with traditional medical imaging technology, molecular imaging technology has the characteristics of assisting early diagnosis. Further, traditional medical imaging technology mainly observes the end effect of molecular changes, which means that observation can be performed after organogenesis. Molecular imaging techniques can observe changes in cell and molecular levels during organ pathogenesis. Therefore, the field of nuclear medicine, which belongs to molecular medicine technology, has become an important diagnostic and research tool for many major diseases, especially malignant tumor imaging.

Nuclear angiography uses radioisotopes to label the tissue to be observed, and detects the radioactive material through a nuclear medical photographic instrument to obtain images of organs or tissues in the living body. In general, radioisotopes are combined with contrast agent precursors to prepare contrast agents for nuclear medicine. According to research by Professor Eric W. Price in 2014, 2,2',2"-(1 ,4,7-triazacyclononane-1,4,7-triyl)triacetic acid (2,2',2"-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic The contrast agent formed by chelation of acid, referred to as NOTA, with gallium-68 ( ⁶⁸ Ga) is generally considered to have good radiolabeling properties and excellent in vivo stability.

In addition, in order to enable specific binding of the contrast agent to a specific tissue, a tissue specific peptide or protein may be further bonded to the structure of the contrast agent precursor, that is, The radioisotope can be brought to a specific target tissue by recognition of the peptide or protein.

However, the three carboxylic acid groups of NOTA are not modified with functional groups for selective protection, so that NOTA will produce many by-products when combined with biomolecules such as peptides or proteins. In addition, conventional preparation of NOTA relies on The separation of impurities by means of column chromatography not only lengthens the preparation time, but also reduces the yield and increases the preparation cost. Therefore, how to solve the problem of producing a large amount of by-products in the preparation process and how to improve the preparation method is an important subject.

The main object of the present invention is to provide a method for preparing a contrast agent precursor which is mono-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl). The diacetic acid, phenyl bromoacetate and a basic compound are co-dissolved in a solvent and simultaneously subjected to a two-molecule nucleophilic substitution reaction, thereby eliminating the problem that the catalyst is poorly soluble in the solvent to reduce the yield.

Another object of the present invention is to provide a method for preparing a contrast agent precursor, which comprises dissolving a product into a solution, and then adjusting the pH value of the solution to make it acidic to extract to remove by-products. When it is made alkaline, it is extracted to obtain a final product, which is purified by a gel column chromatography instead of the prior art, which greatly shortens the preparation time and improves the yield.

In order to achieve the above object, the present invention discloses a method for preparing a contrast agent precursor, which comprises the steps of: taking a di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1 , 4-diyl) double B The acid, phenyl bromoacetate and a basic compound are dissolved together in a first solvent and subjected to a two-molecule nucleophilic substitution reaction to obtain a product; the product is dissolved in a second solvent to obtain a solution; The solution adjusts its pH value. When the solution is acidic, an organic solvent is added, the first organic layer containing the organic solvent is removed, the alkalinity is adjusted, and the organic solvent is added to obtain one of the organic solvents. a second organic layer, which is a di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl-(1,4,7-triaza) Cyclodecane)-1,4-diyl]}diacetic acid.

In one embodiment of the present invention, it is also disclosed in the di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl) diacetic acid, the bromoacetic acid The di-tert-butyl 2,2'-(1,4,7-triaza) is obtained by dissolving the phenyl ester and the basic compound in a first solvent and performing a two-molecule nucleophilic substitution reaction step. Cyclodecane-1,4-diyl)diacetic acid is dissolved in tetrahydrofuran or an anhydrous acetonitrile.

In one embodiment of the invention, it is also disclosed that the basic compound is triethylamine.

In an embodiment of the invention, it is also disclosed that the first solvent is the tetrahydrofuran or the anhydrous acetonitrile.

In one embodiment of the present invention, it is also disclosed that the reaction time of the bimolecular nucleophilic substitution reaction is between 6 and 20 hours.

In one embodiment of the invention, it is also disclosed that the bimolecular nucleophilic substitution reaction is carried out at room temperature.

In one embodiment of the present invention, it is also disclosed that the bimolecular nucleophilic substitution reaction is carried out on the di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl group. A 2-benzyloxy group is formed in the structure of diacetic acid.

In an embodiment of the invention, the second solvent-based water is also disclosed.

In one embodiment of the present invention, it is also disclosed that the organic solvent is monoethyl ether or monomethylene chloride.

First Figure: It is a flow chart of the preparation method of the present invention.

In order to give the reviewer a better understanding and understanding of the features and effects of the present invention, the preferred embodiment and the detailed description will be followed by a description of the following: , 2',2"-(1,4,7-triazacyclononane-1,4,7-triyl)triacetic acid, which produces a large amount of by-products when bonded to biomolecules, resulting in high product complexity And the prior art is to purify the product by column chromatography. Because the extraction time is tedious, the product obtained by chromatography is often an amorphous oil, and it is impossible to find a suitable solvent to recrystallize it into a shaped solid. The invention provides a novel preparation method of a compound, which provides different reaction materials to reduce the formation of impurities, and simplifies the preparation process, effectively shortens the preparation time and improves the production efficiency.

Hereinafter, the chemical materials, properties and preparation methods thereof for preparing the contrast agent precursor of the present invention are further described: refer to the first figure, which is a flow chart of the preparation method of the present invention, as shown in the figure. The preparation method of the contrast agent precursor of the present invention comprises the following steps: Step S2: taking a di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl) The diacetic acid, phenyl bromoacetate and a basic compound are dissolved together in a first solvent and subjected to a two-molecule nucleophilic substitution reaction to obtain a product; Step S4: the product is dissolved in a second solvent to obtain a a solution; and step S6: taking the solution to adjust its acid-base value, when the solution is acidic, adding an organic solvent, removing the first organic layer containing the organic solvent, adjusting to be alkaline, adding the organic Solvent, obtaining a second organic layer containing one of the organic solvents, the second organic layer is di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl-( 1,4,7-triazacyclononane)-1,4-diyl]}diacetic acid.

As described in step S2, the method for preparing a contrast agent precursor provided by the present invention is a di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl group. Di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl)diacetate and benzyl-2-bromoacetate as starting reactants, And co-dissolving in a first solvent together with a basic compound to carry out a two-molecule nucleophilic reaction to form a product.

Wherein the basic compound used in the step S2 is used as a catalyst for the nucleophilic reaction of the two molecules, which is compatible with the first solvent, that is, the basic compound needs to be easily dissolved in the first solvent. In the present embodiment, Triethylamine is used as a catalyst, and the solvent is selected from Tetrahydrofuran or anhydrous acetonitrile, in which the complexity of the reaction product is increased and the reaction yield is lowered. However, the types of catalysts and solvents are not limited to this.

Further, in the above step, the bimolecular nucleophilic substitution reaction has a reaction time of between 6 hours and 20 hours, and a reaction temperature of between 20 ° C and 30 ° C.

Further, the bimolecular nucleophilic substitution reaction in the above step uses the bromoacetic acid phenyl ester as a nucleophilic reagent, since the bromide ion carries a pair of lone pairs of electrons to attack the di-tert-butyl 2,2' -(1,4,7-triazacyclononane-1,4-diyl)diacetic acid to form a 2-benzyloxy (2-benzyloxy) functional group.

Next, as described in the step 4, the method for preparing the contrast agent precursor provided by the present invention comprises the step of concentrating the product obtained in the step 2, and dissolving the concentrated product in a second solvent to obtain a The solution is followed by a subsequent purification step. In the present embodiment, the second solvent is water, but not limited thereto.

Next, as described in the step 6, the method for preparing the contrast agent precursor provided by the present invention extracts and purifies the solution obtained in the step 4. In the present embodiment, the acid-base extraction method is used for the purpose of purification, and the acid-base extraction method dissolves the impurities and products in an acid or alkali environment by using a suitable solvent according to the difference between the acid and the basic substance of the impurities and the product. Extraction to achieve the effect of purification.

Wherein, the solution is first adjusted to an acidic solution by using hydrochloric acid (HCl), and an organic solvent is added. At this time, the impurity is dissolved in the organic solvent to form a first organic layer, thereby achieving the purpose of removing the impurities; Removing the first organic layer containing the organic solvent to obtain an aqueous layer, and adjusting the aqueous layer to an alkaline solution by using water, and then adding the organic solvent, at which time the product is dissolved in the organic solvent to form After the second organic layer is obtained, the organic solvent is dried and dried to obtain a purified product, and the above extraction method is an acid-base extraction method. In the present embodiment, the organic solvent is selected from diethyl ether or dichloromethane, but is not limited thereto.

The chemical reaction formula of the above preparation process is as follows:

The contrast agent precursor obtained by the above preparation process may further be combined with a radioactive isotope, which may be selected from radioisotopes commonly used in the field of nuclear medicine, such as 鎝-99m ( ^99m Tc), iodine-123 ( ¹²³ I) or gallium-68 ( ⁶⁸ Ga), and the preferred choice in this embodiment is gallium-68, which is similar to the pharmacokinetic properties of most peptides and small molecule drugs, and has good radioactive labeling properties and excellent in vivo. Stability, also has a higher blood clearance rate; in addition, according to the target tissue of the pre-detection, a tissue-specific peptide or protein can be selected and further bonded to the contrast agent precursor to make it specific. Identify tissues and bring radioisotopes to these tissues. For example, integrin α _v β ₃ (integrin α _v β ₃ ) is a cell adhesion receptor associated with tumor angiogenesis and tumor metastasis, and RGD peptides and integration Su α _v β ₃ have high binding specificity, and therefore by the RGD peptide may be bonded to the contrast agent precursor, it has the effect of specifically binding to tumor tissue.

In the following, the specific examples of the embodiments are used for the description of the technical contents, features and results of the present invention, and may be implemented according to the embodiments, but the scope of protection of the present invention is not limited thereto.

Di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl-(1,4,7-triazacyclononane)-1,4-diyl] } Synthesis of diacetic acid

2.92 g (g), 8.17 mmol (mmol) of starting material di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl) diacetic acid Dissolve in 20 ml (ml) of anhydrous acetonitrile, add 1.3 ml, 8.99 mmol of triethylamine, then take 1.5 ml of 8.99 mmol of phenyl bromoacetate (benzyl-2). -bromoacetate) was slowly added to the above solution and stirred at room temperature until overnight to obtain a starting solution.

The starting solution was concentrated, and the concentrated product was dissolved in 30 ml of water to obtain a product solution. Then adjusting the pH value of the product solution to pH=3 with 1 equivalent of (N) hydrochloric acid (HCl), and extracting twice with 60 ml of diethyl ether to remove the impurities in the product solution; then taking out the product solution. The aqueous layer was taken, and the pH of the product solution was adjusted to pH = 8 and extracted twice with 60 ml of diethyl ether to obtain an organic layer. The organic layer was then dried and dried to give 2.97 g of a yellowish white solid compound as di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl- ( 1,4,7-triazacyclononane)-1,4-diyl]}diacetic acid.

Di-tert-butyl 2,2'-{7-[2-(benzyloxy)-2-oxoethyl-(1,4,7-triazacyclononane)-1,4-diyl] Analysis data for diacetic acid: ¹ H NMR (CDCl ₃ , 300 MHz): δ 7.35 (m, 5H, H ₁₉ , H ₂₀ , H ₂₁ , H ₂₂ , H ₂₃ ), 5.13 (s, 2H, H ₁₇ ), 3.58(s, 2 H, H ₁₅ ), 3.48 (s, 4 H, H ₇ , H ₁₁ ), 2.9-3.1 (m, 12 H, H ₁ , H ₂ , H ₃ , H ₄ , H ₅ , H ₆ ), 1.45 (s, 18 H, H ₁₀ , H ₁₄ ); ESI-MS: m/z = 506.46 (M+H) ⁺ .

In summary, it can be seen that the method for preparing a contrast agent precursor provided by the present invention uses triethylamine as di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1 , 4-diyl) diacetic acid and bromoacetic acid phenyl ester bi-molecular nucleophilic reaction catalyst, reducing by-product formation, thereby reducing product complexity, in addition, it replaces conventional column chromatography with acid-base extraction The product is purified, the preparation time is greatly reduced and the production efficiency is improved, and the bottleneck of the recrystallization reaction which can not be solved by the conventional method for purifying the product is solved, and the preparation of di-tert-butyl 2,2'-{7-[2-(benzyloxy) is actually carried out. One of the major breakthroughs in the group of 2-oxyethyl-(1,4,7-triazacyclononane)-1,4-diyl]} diacetic acid.

The above is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and the variations, modifications, and modifications of the shapes, structures, features, and spirits described in the claims of the present invention. All should be included in the scope of the patent application of the present invention.

Claims (5)

A method for preparing a contrast agent precursor, the contrast agent precursor comprising a chemical structure: The method comprises the steps of: taking a di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-diyl) diacetic acid, phenyl monobromoacetate and a basic compound Co-dissolved in an anhydrous acetonitrile and subjected to a two-molecule nucleophilic substitution reaction to obtain a product; the product is dissolved in water to obtain a solution; and the solution is adjusted to have a pH value, when the solution is acidic, Adding diethyl ether, removing the first organic layer containing the ether, adjusting to basicity, adding the diethyl ether to obtain a second organic layer containing the diethyl ether, the second organic layer is a di-tert-butyl 2,2 '-{7-[2-(Benzyloxy)-2-oxoethyl-(1,4,7-triazacyclononane)-1,4-diyl]}diacetic acid. Wherein the basic compound is triethylamine, which serves as a catalyst for the bimolecular nucleophilic reaction. The method for preparing a contrast agent precursor according to claim 1, wherein the di-tert-butyl 2,2'-(1,4,7-triazacyclononane-1,4-di Taking the di-tert-butyl group, the bromoacetic acid phenyl ester and the basic compound together in the anhydrous acetonitrile and performing a two-molecule nucleophilic substitution reaction step, the di-tert-butyl 2,2'-(1, 4,7-Triazacyclononane-1,4-diyl)diacetic acid is dissolved in tetrahydrofuran or an anhydrous acetonitrile. The method for preparing a contrast agent precursor according to claim 1, wherein the reaction time of the bimolecular nucleophilic substitution reaction is between 6 and 20 hours. The method for preparing a contrast agent precursor according to claim 1, wherein the bimolecular nucleophilic substitution reaction is carried out at room temperature. The method for preparing a contrast agent precursor according to claim 1, wherein the bimolecular nucleophilic substitution reaction is carried out in the di-tert-butyl 2,2'-(1,4,7-triazacyclononane). A 2-benzyloxy group is formed in the structure of alkane-1,4-diyl)diacetic acid.