CN114349778A - Small molecular probe for brain glioma imaging and preparation method thereof - Google Patents

Abstract

The invention discloses a small molecular probe for brain glioma imaging, which is characterized in that: the small molecular probe is a double-amino-acid small molecular probe Al¹⁸F, the chemical structural formula is as follows:

Al¹⁸f has the characteristics of simple labeling method and high specific uptake of brain glioma, and Al¹⁸F can be carried out in a water environment, and can shorten the labeling time and simplify the labeling process, so that an ideal ligand compound can be screened, Al18F radiopharmaceuticals with high stability, specificity and biological activity can be prepared, and a PET imaging agent capable of realizing kit formation can be prepared.

Description

Small molecular probe for brain glioma imaging and preparation method thereof

Technical Field

The invention relates to a medical PET/CT imaging agent, in particular to a small molecular probe for brain glioma imaging and a preparation method thereof.

Background

¹⁸F-FDG is a glucose analog, which is taken up significantly more in tumor cells than in normal cells, and is currently the most commonly used tumor imaging agent. But do not¹⁸F-FDG has a great limitation in the diagnosis of brain tumors.¹⁸High uptake of F-FDG in the normal cerebral cortex for primary or metastatic brain tumors, especially low-grade brain gliomas,with large interference, it is difficult to obtain images with sufficient contrast, and it is difficult to determine the boundary of brain tumor and the infiltration range of tumor tissue.¹¹C-MET and¹⁸the imaging effect of the F-FET is better¹⁸F-FDG is a significant improvement, but is still insufficient for accurate diagnosis of tumors.

Therefore, it is required to develop a PET molecular probe with higher specificity for early diagnosis of brain glioma.

Disclosure of Invention

In view of the above, the present invention provides a small molecule probe for brain glioma imaging and a preparation method thereof, and Al¹⁸F has the characteristics of simple labeling method and high specific uptake of brain glioma, and Al¹⁸F can be carried out in a water environment, and can shorten the labeling time and simplify the labeling process, so that an ideal ligand compound can be screened, Al18F radiopharmaceuticals with high stability, specificity and biological activity can be prepared, and a PET imaging agent capable of realizing kit formation can be prepared.

The invention relates to a small molecular probe for brain glioma imaging, which is a double-amino-acid small molecular probe Al¹⁸F, the chemical structural formula is as follows:

the invention also discloses a preparation method of the small molecular probe for brain glioma imaging, which comprises the following steps:

a.BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthetic route of (1) comprises:

(3)b.Al¹⁸f molecular probe preparation, the synthetic route is as follows:

further, in scheme (1) of step a, synthesis of a compound of formula (2): dropwise adding MeCOCl into anhydrous methanol, stirring uniformly, adding the compound of the formula (1), stirring uniformly, removing the solvent under reduced pressure, treating the residue with diethyl ether, filtering, and drying to obtain a white solid compound of the formula (2);

synthesis of a compound of formula (3): reacting imidazole-1-sulfonyl azide with a compound of formula (2), K₂CO₃And CuSO₄·5H₂Stirring in methanol slurry overnight, concentrating the mixture, diluting with water, acidifying with concentrated hydrochloric acid, extracting with ethyl acetate, and collecting the organic layer (MgSO)₄Drying, filtering and concentrating to obtain a crude product of the formula (3), and purifying the crude product by silica gel chromatography through nuclear magnetic resonance spectroscopy to obtain a colorless liquid compound of the formula (3);

further, in scheme (1) of step a, synthesis of a compound of formula (4): adding TsCl to a solution of the compound of formula (3) and TEA in DCM, stirring overnight at room temperature, then washing the mixture with water, drying over magnesium sulphate and filtering, concentrating the filtrate and purifying to give the compound of formula (4) as a white solid;

further, synthesis of the compound of formula (5): in NO₂A (tBu) and Cs₂CO₃Adding the compound of formula (4) to the mixture of (1), cooling to room temperature, heating at 45-55 deg.C for over 24 hours, filtering, concentrating and purifying the residue by silica gel column chromatography to obtain the compound of formula (5) as a yellow liquid.

Further, synthesis of the compound of formula (6): adding LII into pyridine solution of the compound shown in the formula (5), stirring at room temperature for 3-5h, adding DCM into the mixture, washing with saturated citric acid and water, drying an organic layer with magnesium sulfate, filtering, concentrating to obtain a crude product of the compound shown in the formula (6), and then purifying by silica gel chromatography to obtain the compound shown in the formula (6);

further, synthesis of the compound of formula (7): mixing the compound shown in the formula (6) with HATU and DIEA, adding methionine, mixing in DMF at room temperature for 1.5-3h, and purifying by high performance liquid chromatography to obtain a compound shown in the formula (7);

further, synthesis of the compound of formula (9): mixing the compound of the formula (8), tyrosine and DIEA, adding the mixture into DMF (dimethyl formamide) to react for 3.5 to 4.5 hours at room temperature, and purifying to obtain a compound of the formula (9);

further, synthesis of a compound of formula (10): mixing the compound shown in the formula (9) and the compound shown in the formula (7) in 50% of MeCN/H2O, reacting overnight at room temperature, and freeze-drying to obtain a combination;

further, in step b, Al¹⁸The preparation of the F molecular probe comprises the following steps:

s1, mixing with 0.9% sodium chloride solution¹⁸F-is eluted from the QMA column into the reaction tube, the pH is adjusted to 3-4 with glacial acetic acid, and then AlCl is added thereto₃The solution is kept stand for 7-15min at room temperature to obtain the (Al-¹⁸F)²⁺The solution of the compound is mixed with the water,

s2, dissolving the compound of formula (10) in sodium acetate buffer solution, and adding into a solution containing (Al-¹⁸F)²⁺Reacting in the complex solution at 100-120 deg.C for 10-15min, purifying the obtained mixed solution with pretreated HLB column, washing with water to remove unreacted (Al-¹⁸F)²⁺And the rest 18F-, and finally leaching with ethanol water solution to obtain a marked product 11;

s3, separating the marked product 11 by HPLC to obtain the marker with the radiochemical purity of more than 99 percent.

The invention has the beneficial effects that: the invention discloses a small molecular probe for brain glioma imaging and a preparation method thereof, and Al¹⁸F has the characteristics of simple labeling method and high specific uptake of brain glioma, and Al¹⁸F can be carried out in a water environment, and can shorten the labeling time and simplify the labeling process, so that an ideal ligand compound can be screened, Al18F radiopharmaceuticals with high stability, specificity and biological activity can be prepared, and a PET imaging agent capable of realizing kit formation can be prepared.

Drawings

The invention is further described below with reference to the following figures and examples:

FIG. 1 is a PET/CT image of a probe of the invention after 1 hour in normal rats;

FIG. 2 is a graph showing the effect of the probe of the present invention on imaging in the brain of a brain glioma volunteer.

Detailed Description

Example one

The small molecular probe Al for brain glioma imaging of the embodiment¹⁸The synthetic route of F is as follows:

the method comprises the following specific steps:

(1)BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthesis of (2):

synthesis of Compound 2: 15ml of MeCOCl was added dropwise to 100ml of anhydrous methanol (100ml), and stirred at room temperature for 1 hour, followed by addition of starting material 1(10g) and stirring at room temperature for 2 hours. Removing solvent under reduced pressure, treating residue with diethyl ether (50ml), filtering, and drying to obtain white solid compound 2;

synthesis of Compound 3: reacting imidazole-1-sulfonyl azide [2 ]](2.5g) 2(1.7g, 5mmol), K2CO3(3.2g) and CuSO were added₄·5H₂O (30mg) methanol (30ml) was stirred in a slurry overnight. The mixture was concentrated, diluted with 100ml of water, acidified with concentrated hydrochloric acid and extracted with ethyl acetate (50X 3 ml). The organic layer (MgSO4) was dried, filtered and concentrated to give crude 3(1.22g, 76.6%) as a colourless liquid. The crude product was used in the next step without further purification. NMR spectroscopy was purified by silica gel chromatography (DCM/MeOH, 10: 1) to give compound 3 as a colorless liquid.

Synthesis of Compound 4: TsCl (2.7g) was added to a solution of 3(1.5g) and TEA (3g) in DCM (50ml) and stirred at room temperature overnight. The mixture was then washed with water (30 × 2ml), dried over magnesium sulfate and filtered. The filtrate was concentrated and purified to give compound 4 as a white solid.

Synthesis of Compound 5: in NO₂A (tBu) (0.8g) and Cs₂CO₃(1.1g) Compound 4(0.95g) was added to the mixture, cooled to room temperature, heated at 50 ℃ for 1d, filtered and concentrated. Purify the residue by silica gel column chromatography ((DCM/MeOH, 10: 1) to obtain Compound II as a yellow liquidObject 5.

Synthesis of Compound 6: LII (134mg, N) was added to a pyridine solution (2ml) of Compound 5(100mg), and the mixture was stirred at room temperature for 4 hours. DCM (20ml) was added to the mixture and washed with saturated citric acid (2ml, multiple times) and water (20 ml). The organic layer was dried over magnesium sulfate, filtered and concentrated to give crude 6. Purification by silica gel chromatography gave white solid 6.

Synthesis of compound 7: after mixing compound 6(3eq.) with HATU (5eq.) and DIEA (10eq.), methionine was added and mixed in DMF (1-2 mL) for 2h at room temperature. Purifying by high performance liquid chromatography to obtain compound 7.

Synthesis of compound 9: and mixing the compound 8 with tyrosine and DIEA (3-5 eq.), adding the mixture into DMF (0.1-0.3 mL) to react for 4 hours at room temperature, and purifying to obtain a compound 9.

Synthesis of compound 10: the compound 9(1eq.) and the compound 7(1eq.) were mixed in 50% MeCN/H2O (0.5-1 mL), reacted overnight at room temperature, and freeze-dried to give a conjugate. The reaction is usually carried out in quantitative yield (one part of which is completely reacted). The purity can reach more than 95 percent, and high performance liquid chromatography (Hplc) purification is not needed.

(2)Al¹⁸Preparation of F molecular probe:

using 0.9% sodium chloride solution (0.5mL)¹⁸The F-was rinsed from the QMA column into the reaction tube and the pH was adjusted to around 4 with glacial acetic acid. To which AlCl is added₃The solution (2mM, 22.5. mu.L, pH4) was allowed to stand at room temperature for 10min to obtain a solution containing (Al-¹⁸F)²⁺The precursor compound 10 was dissolved in sodium acetate buffer (0.1M, pH4, 500nmol/mL) and added to the above solution to react at 110 ℃ for 12 min. The mixed solution is purified by a pretreated HLB column and is washed by 5mL of water to remove unreacted (Al-¹⁸F)²⁺And the remaining 18F-, and finally rinsing with aqueous ethanol (50%, 2mL) to obtain the labeled product¹⁸F-3.17. Separation by HPLC (C18 semi-preparative column, 5 μm,10 mm. times.250 mm, CH)₃CN/H₂O40%/60%, flow rate 1mL/min) to give a label with radiochemical purity greater than 99%.

Example two

(1)BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthesis of (2):

synthesis of Compound 2: 10-15ml of MeCOCl is added dropwise to 90-110ml of anhydrous methanol, stirred at room temperature for 0.8-1.2h, then added with the raw material 1(8-12g), and stirred at room temperature for 1.5-2.5 h. Removing solvent under reduced pressure, treating residue with diethyl ether (40-60ml), filtering, and drying to obtain white solid compound 2;

synthesis of Compound 3: imidazole-1-sulfonyl azide (2-3g) was added to 2(1-2g), K2CO3(2.5-5g) and CuSO₄·5H₂O (20-40mg) methanol (20-40ml) was stirred in a slurry overnight. The mixture was concentrated, diluted with 90-110ml of water, acidified with concentrated hydrochloric acid and extracted with ethyl acetate (50X 3 ml). The organic layer (MgSO4) was dried, filtered and concentrated to give crude 3 as a colourless liquid. The crude product was used in the next step without further purification. NMR spectroscopy was purified by silica gel chromatography (DCM/MeOH, 10: 1) to give compound 3 as a colorless liquid.

Synthesis of Compound 4: TsCl (2-4g) was added to a solution of 3(0.5-2g) and TEA (2-4g) in DCM (40-60ml) and stirred at room temperature overnight. The mixture was then washed with water, dried over magnesium sulfate and filtered. The filtrate was concentrated and purified to give compound 4 as a white solid.

Synthesis of Compound 5: in NO₂A (tBu) (0.5-1.5g) and Cs₂CO₃(0.5-1.5g) Compound 4(0.5-1.5g) was added to the mixture, cooled to room temperature, heated at 40-60 ℃ for 24 hours or more, filtered and concentrated. The residue was purified by silica gel column chromatography ((DCM/MeOH, 8-11: 1) to give Compound 5 as a yellow liquid.

Synthesis of Compound 6: LII (110-150mg) was added to a pyridine solution (1-4ml) of Compound 5(80-120mg), stirred at room temperature for 3-6h, DCM (15-25ml) was added to the mixture, and washed with saturated citric acid (1-3ml, several times) and water (10-30 ml). The organic layer was dried over magnesium sulfate, filtered and concentrated to give crude 6. Purification by silica gel chromatography gave white solid 6.

Synthesis of compound 7: after mixing the compound 6(2-4eq.) with HATU (3-7eq.) and DIEA (8-12eq.), methionine was added and mixed in DMF (1-2 mL) at room temperature for 1-3 h. Purifying by high performance liquid chromatography to obtain compound 7.

Synthesis of compound 9: and mixing the compound 8 with tyrosine and DIEA (3-5 eq.), adding the mixture into DMF (0.1-0.3 mL) to react for 2-6h at room temperature, and purifying to obtain a compound 9.

Synthesis of compound 10: the compound 9(0.5-1.5eq.) and the compound 7(0.5-1.5eq.) were mixed in 50% MeCN/H2O (0.5-1 mL), reacted overnight at room temperature, and freeze-dried to give a conjugate. The reaction is usually carried out in quantitative yield (one part of which is completely reacted). The purity can reach more than 95 percent, and high performance liquid chromatography (Hplc) purification is not needed.

(2)Al¹⁸Preparation of F molecular probe:

using 0.9% sodium chloride solution (0.1-1mL)¹⁸The F-was rinsed from the QMA column into the reaction tube and the pH was adjusted to around 4 with glacial acetic acid. To which AlCl is added₃The solution (1-4mM pH4) is left standing for 8-12min at room temperature to obtain the solution containing (Al-¹⁸F)²⁺The compound solution is prepared by dissolving the precursor compound 10 in sodium acetate buffer solution (0.1M, pH4), adding into the above solution, and reacting at 110 deg.C for 10-15 min. The mixed solution is purified by a pretreated HLB column and is washed by 3-8mL of water to remove unreacted (Al-¹⁸F)²⁺And the remaining 18F-, and finally rinsing with an aqueous ethanol solution (50%, 1-5mL) to obtain the labeled product¹⁸F-3.17. Separation by HPLC (C18 semi-preparative column, 5 μm,10 mm. times.250 mm, CH)₃CN/H₂O40%/60%, flow rate 1mL/min) to give a label with radiochemical purity greater than 99%.

EXAMPLE III

(1)BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthesis of (2):

synthesis of Compound 2: 10ml of MeCOCl was added dropwise to 110ml of anhydrous methanol, and stirred at room temperature for 0.5h, followed by addition of starting material 1(8g) and stirring at room temperature for 1 h. Removing solvent under reduced pressure, treating residue with diethyl ether (40ml), filtering, and drying to obtain white solid compound 2;

synthesis of Compound 3: imidazole-1-sulfonyl azide (2g) was added to 2(1g), K2CO3(2.8g, N) and CuSO₄·5H₂O (25mg) methanol (20ml) was stirred in a slurry overnight. The mixture was concentrated, diluted with 80ml of water, acidified with concentrated hydrochloric acid and extracted with ethyl acetate (50X 3 ml). The organic layer (MgSO4) was dried, filtered and concentrated to give crude 3(12g) as a colorless liquid. The crude product was used in the next step without further purification. NMR spectroscopy was purified by silica gel chromatography (DCM/MeOH, 10: 1) to give compound 3 as a colorless liquid.

Synthesis of Compound 4: TsCl (2g) was added to a solution of 3(1g) and TEA (2g) in DCM (40ml) and stirred at room temperature overnight. The mixture was then washed with water (30 × 2ml), dried over magnesium sulfate and filtered. The filtrate was concentrated and purified to give compound 4 as a white solid.

Synthesis of Compound 5: in NO₂A (tBu) (0.5g) and Cs₂CO₃(0.9g) Compound 4(0.5g) was added to the mixture, cooled to room temperature, heated at 40 ℃ for 1d, filtered and concentrated. The residue was purified by silica gel column chromatography ((DCM/MeOH, 10: 1) to give Compound 5 as a yellow liquid.

Synthesis of Compound 6: LII (130mg, N) was added to a pyridine solution (1ml) of Compound 5(80mg), and the mixture was stirred at room temperature for 4 hours. DCM (15ml) was added to the mixture and washed with saturated citric acid (1ml, multiple times) and water (15 ml). The organic layer was dried over magnesium sulfate, filtered and concentrated to give crude 6. Purification by silica gel chromatography gave white solid 6.

Synthesis of compound 7: after mixing compound 6(2eq.) with HATU (2eq.) and DIEA (8eq.), methionine was added and mixed in DMF (1-2 mL) at room temperature for 1 h. Purifying by high performance liquid chromatography to obtain compound 7.

Synthesis of compound 9: after compound 8 was mixed with tyrosine and DIEA (3eq.) and added to DMF (0.1mL) for reaction at room temperature for 2h, compound 9 was obtained after purification.

Synthesis of compound 10: compound 9(1eq.) and compound 7(1eq.) were mixed in 50% MeCN/H2O (0.5-mL), reacted overnight at room temperature, and lyophilized to give a conjugate. The reaction is usually carried out in quantitative yield (one part of which is completely reacted). The purity can reach more than 95 percent, and high performance liquid chromatography (Hplc) purification is not needed.

(2)Al¹⁸Preparation of F molecular probe:

using 0.9% sodium chloride solution (0.3mL)¹⁸The F-was rinsed from the QMA column into the reaction tube and the pH was adjusted to around 4 with glacial acetic acid. To which AlCl is added₃The solution (1mM, pH4) was left standing at room temperature for 8min to obtain a solution containing (Al-¹⁸F)²⁺The precursor compound 10 is dissolved in sodium acetate buffer solution (0.05M, pH4) and added into the solution to react at 110 deg.C for 12 min. The mixed solution is purified by a pretreated HLB column and is washed by 5mL of water to remove unreacted (Al-¹⁸F)²⁺And the rest of¹⁸F-, and finally leaching with ethanol aqueous solution (50%, 2mL) to obtain a marked product¹⁸F-3.17. Separation by HPLC (C18 semi-preparative column, 5 μm,10 mm. times.250 mm, CH)₃CN/H₂O40%/60%, flow rate 1mL/min) to give a label with radiochemical purity greater than 99%.

Example four

(1)BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthesis of (2):

synthesis of Compound 2: 15ml of MeCOCl was added dropwise to 110ml of anhydrous methanol, and stirred at room temperature for 1.2 hours, followed by addition of starting material 1(12g) and stirring at room temperature for 2.5 hours. Removing solvent under reduced pressure, treating residue with diethyl ether (60ml), filtering, and drying to obtain white solid compound 2;

synthesis of Compound 3: imidazole-1-sulfonyl azide (3g) was added to 2(2g), K2CO3(-5g) and CuSO₄·5H₂O (40mg) methanol (40ml) was stirred in a slurry overnight. The mixture was concentrated, diluted with 110ml of water, acidified with concentrated hydrochloric acid and extracted with ethyl acetate (50X 3 ml). The organic layer (MgSO4) was dried, filtered and concentrated to give crude 3 as a colourless liquid. The crude product was used in the next step without further purification. NMR spectroscopy was purified by silica gel chromatography (DCM/MeOH, 10: 1) to give compound 3 as a colorless liquid.

Synthesis of Compound 4: TsCl (4g) was added to a solution of 3(2g) and TEA (4g) in DCM (60ml) and stirred at room temperature overnight. The mixture was then washed with water, dried over magnesium sulfate and filtered. The filtrate was concentrated and purified to give compound 4 as a white solid.

Synthesis of Compound 5: in NO₂A (tBu) (1.5g) and Cs₂CO₃(1.5g) Compound 4(1.5g) was added to the mixture, cooled to room temperature, heated at 60 ℃ for 24 hours or more, filtered and concentrated. The residue was purified by silica gel column chromatography ((DCM/MeOH, 11: 1) to give Compound 5 as a yellow liquid.

Synthesis of Compound 6: LII (150mg) was added to a pyridine solution (4ml) of Compound 5(120mg), stirred at room temperature for 6h, DCM (25ml) was added to the mixture, and washed with saturated citric acid (3ml, ca.) and water (30 ml). The organic layer was dried over magnesium sulfate, filtered and concentrated to give crude 6. Purification by silica gel chromatography gave white solid 6.

Synthesis of compound 7: after mixing compound 6(4eq.) with HATU (7eq.) and DIEA (12eq.), methionine was added and mixed in DMF (1-2 mL) for 3h at room temperature. Purifying by high performance liquid chromatography to obtain compound 7.

Synthesis of compound 9: after compound 8 was mixed with tyrosine and DIEA (5eq.) and added to DMF (0.3mL) for reaction at room temperature for 6h, compound 9 was obtained after purification.

Synthesis of compound 10: compound 9(1.5eq.) and compound 7(1.5eq.) were mixed in 50% MeCN/H2O (1mL), reacted overnight at room temperature, and lyophilized to give a conjugate. The reaction is usually carried out in quantitative yield (one part of which is completely reacted). The purity can reach more than 95 percent, and high performance liquid chromatography (Hplc) purification is not needed.

(2)Al¹⁸Preparation of F molecular probe:

with 0.9% sodium chloride solution (1mL)¹⁸The F-was rinsed from the QMA column into the reaction tube and the pH was adjusted to around 4 with glacial acetic acid. To which AlCl is added₃The solution (4mM pH4) was allowed to stand at room temperature for 12min to obtain a solution containing (Al-¹⁸F)²⁺The precursor compound 10 is dissolved in sodium acetate buffer solution (0.1M, pH4) and added to the solution to react at 120 deg.C for 15 min. The mixed solution is purified by a pretreated HLB column and is washed by 8mL of water to remove unreacted (Al-¹⁸F)²⁺And the rest of¹⁸F-and finallyLeaching with ethanol water solution (50%, 5mL) to obtain labeled product¹⁸F-3.17. Separation by HPLC (C18 semi-preparative column, 5 μm,10 mm. times.250 mm, CH)₃CN/H₂O40%/60%, flow rate 1mL/min) to give a label with radiochemical purity greater than 99%.

Al of the first example¹⁸The F molecular probe is used for mouse test, the test method is the conventional test method, and the test result is shown in figure 1. Mixing Al¹⁸The F molecular probe is applied to glioma volunteers, and the imaging effect of the F molecular probe in the brain of the glioma volunteers is shown in figure 2. Through tests, the molecular probe has good stability in a normal mouse. The imaging effect is better in human brain glioma volunteers. The novel double-amino-acid small molecular probe has high specific uptake in brain glioma, good imaging contrast and clinical transformation application potential.

Finally, the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting, although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions may be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all of them should be covered in the claims of the present invention.

Claims (10)

1. A small molecule probe for brain glioma imaging, comprising: the small molecular probe is a double-amino-acid small molecular probe Al¹⁸F, the chemical structural formula is as follows:

2. the method for preparing a small molecule probe for brain glioma imaging according to claim 1, wherein the method comprises the following steps: the method comprises the following steps:

a.BFC(N₃-NO^tB₂/N₃-DO^tB₃) The synthetic route of (1) comprises:

(1)

(2)

b.Al¹⁸f molecular probe preparation, the synthetic route is as follows:

3. the method for preparing a small molecule probe for brain glioma imaging according to claim 2, wherein the method comprises the following steps: in scheme (1) of step a, synthesis of a compound of formula (2): dropwise adding MeCOCl into anhydrous methanol, stirring uniformly, adding the compound of the formula (1), stirring uniformly, removing the solvent under reduced pressure, treating the residue with diethyl ether, filtering, and drying to obtain a white solid compound of the formula (2);

synthesis of a compound of formula (3): reacting imidazole-1-sulfonyl azide with a compound of formula (2), K₂CO₃And CuSO₄·5H₂Stirring in methanol slurry overnight, concentrating the mixture, diluting with water, acidifying with concentrated hydrochloric acid, extracting with ethyl acetate, and collecting the organic layer (MgSO)₄Drying, filtering and concentrating to obtain a crude product of the formula (3), and purifying the crude product by silica gel chromatography through nuclear magnetic resonance spectroscopy to obtain a colorless liquid compound of the formula (3).

4. The method for preparing a small molecule probe for brain glioma imaging according to claim 3, wherein the method comprises the following steps: in scheme (1) of step a, synthesis of a compound of formula (4): the compound of formula (4) is obtained by adding TsCl to a solution of the compound of formula (3) and TEA in DCM, stirring overnight at room temperature, washing the mixture with water, drying over magnesium sulphate and filtering, and concentrating and purifying the filtrate.

5. The method for preparing a small molecule probe for brain glioma imaging according to claim 3, wherein the method comprises the following steps: synthesis of a compound of formula (5): in NO₂A (tBu) and Cs₂CO₃Adding the compound of formula (4) to the mixture of (1), cooling to room temperature, heating at 45-55 deg.C for over 24 hours, filtering, concentrating and purifying the residue by silica gel column chromatography to obtain the compound of formula (5) as a yellow liquid.

6. The method for preparing a small molecule probe for brain glioma imaging according to claim 5, wherein the method comprises the following steps: synthesis of a compound of formula (6): LII is added to the pyridine solution of the compound of formula (5) and stirred at room temperature for 3-5h, then DCM is added to the mixture and the mixture is washed with saturated citric acid and water, the organic layer is dried over magnesium sulfate, filtered and concentrated to obtain the crude product of the compound of formula (6), and then purified by silica gel chromatography to obtain the compound of formula (6).

7. The method for preparing a small molecule probe for brain glioma imaging according to claim 6, wherein the method comprises the following steps: synthesis of a compound of formula (7): mixing the compound shown in the formula (6) with HATU and DIEA, adding methionine, mixing in DMF at room temperature for 1.5-3h, and purifying by high performance liquid chromatography to obtain the compound shown in the formula (7).

8. The method for preparing a small molecule probe for brain glioma imaging according to claim 7, wherein the method comprises the following steps: synthesis of a compound of formula (9): and (3) mixing the compound shown in the formula (8), tyrosine and DIEA, adding the mixture into DMF (dimethyl formamide) to react for 3.5 to 4.5 hours at room temperature, and purifying to obtain the compound shown in the formula (9).

9. The method for preparing a small molecule probe for brain glioma imaging according to claim 8, wherein the method comprises the following steps: synthesis of a Compound of formula (10): the compound of formula (9) and the compound of formula (7) were mixed in 50% MeCN/H2O, reacted overnight at room temperature and lyophilized to give a conjugate.

10. The method for preparing a small molecule probe for brain glioma imaging according to claim 9, wherein the method comprises the following steps: in step b, Al¹⁸The preparation of the F molecular probe comprises the following steps:

s1, mixing with 0.9% sodium chloride solution¹⁸F-is eluted from the QMA column into the reaction tube, the pH is adjusted to 3-4 with glacial acetic acid, and then AlCl is added thereto₃The solution is kept stand for 7-15min at room temperature to obtain the (Al-¹⁸F)²⁺The solution of the compound is mixed with the water,

s2, dissolving the compound of formula (10) in sodium acetate buffer solution, and adding into a solution containing (Al-¹⁸F)²⁺Reacting in the complex solution at 100-120 deg.C for 10-15min, purifying the obtained mixed solution with pretreated HLB column, washing with water to remove unreacted (Al-¹⁸F)²⁺And the rest 18F-, and finally leaching with ethanol water solution to obtain a marked product 11;

s3, separating the marked product 11 by HPLC to obtain the marker with the radiochemical purity of more than 99 percent.

Images