TW201713632A - Method for preparing DOTA derivative organic ligand which is a precursor DOTA-tris(tBu ester) of hypoxic tissue contrast agent DOTA-Ni with significant cost advantage in the preparation - Google Patents

Abstract

The present invention relates to a method for preparing DOTA derivative organic ligand, which uses benzyl bromoacetate as one of the reactants in the synthesis process. Firstly, the starting materials 1,4,7,10-tetrazacyclododecane, sodium acetate and tert-butyl bromoacetate are reacted in the first solvent to give 1,4,7,10-tris(tert-butoxycarbonylmethy)-1,4,7,10-tetrazacyclododecane, which is then reacted with benzyl bromoacetate in the second solvent to produce 1-(benzyl acetate)-4,7,10-tris(tert-butoxycarbonylmethy)-1,4,7,10-tetrazacyclododecane), which is then subjected to hydrogenated reduction to obtain 1-(acetate acid)-4,7,10-tris(tert-butoxycarbonylmethy)-1,4,7,10-tetrazacyclododecane), which is a precursor DOTA-tris(tBu ester) of hypoxic tissue contrast agent DOTA-Ni. It has significant cost advantage in the preparation.

Description

Method for preparing organic ligand of DOTA derivative

The present invention relates to a preparation method, in particular to a method for preparing a DOTA derivative DOTA-tris ( ^t Bu ester) which can be used as a precursor of the hypoxic tissue contrast agent DOTA-Ni.

Malignant tumors have a cell proliferation rate that exceeds the proliferation of blood vessels. Therefore, for larger tumors, the inside is often insufficiently supplied by blood and oxygen, and a considerable proportion of hypoxic or necrotic cells are present. The tolerance of hypoxic cells to free radiation is about 3 times that of normal cells. For radiation therapy of tumors, how to determine the anoxic site and appropriate sensitization treatment to improve the lethality of free radiation on hypoxic cells, It is an important factor in the success of this treatment.

Therefore, there is room for application of hypoxic tissue contrast agent; however, the hypoxic tissue contrast agent DOTA-Ni is taken as an example, although it can be obtained through commercial purchase, but the purchase cost is high, up to NT$12,000 per 250mg. Spectrum, which severely limits the possibilities for its widespread use. Therefore, under this high-cost background, there is an incentive to find a self-synthesis method in this technical field.

The currently known synthesis method uses 1,4,7,10-tetraaza as a main structure, and is synthesized in the process using triethyl bromoacetate, but this makes the process impossible to directly perform ordinary thin layer chromatography ( Thin layer chromatography (TLC) tracking, so additional coloring agent must be added for progress tracking; in addition, the intermediate product is mostly non-absorbed at 254nm, which makes separation difficult and difficult to track the exact reaction time, so the existing synthesis method is still There is room for improvement.

The main object of the present invention is to provide a method for preparing an organic ligand of a DOTA derivative, which uses benzyl bromoacetate as one of the reactants in the synthesis process, can improve the product identification degree and master the process progress, and DOTA- The cost of tris( ^t Bu ester) is reduced by about 85%, which means that the cost is much lower than that of commercially available products, which has significant economic competitiveness and helps to reduce the application of related contrast agents.

Another object of the present invention is to provide a method for preparing a DOTA derivative organic ligand, which can be used as a hypoxic tissue contrast agent precursor, and the finished product is treated with 6-(2-nitro-1H-imidazole- After coupling with 1-yl)hexan-1-amine (6-(2-nitro-1H-imidazol-1-yl)hexan-1-amine), an anoxic tissue contrast agent DOTA-NI can be formed.

A further object of the present invention is to provide a method for preparing a DOTA derivative organic ligand, which is verified by nuclear magnetic resonance spectroscopy and mass spectrometry data, and the yield is as high as 89%.

In order to achieve the above object, the present invention discloses a method for preparing an organic ligand of a DOTA derivative, which comprises the steps of: using 1,4,7,10-tetraazacyclododecane (1,4,7,10-tetraazacyclododecane) And sodium acetate is dissolved in a first solvent to form a first solution; tert-butyl bromoacetate is added to the first solution to form a second solution; adding hydrogen carbonate Sodium (NaHCO ₃ ) is added to the second solution to produce a precipitate which is filtered and dried under reduced pressure to obtain 1,4,7,10-tris(t-butoxycarbonyl).
-1,4,7,10-tetraaza (1,4,7,10-Tris(tert-butoxycarbonylmethyl)
-1,4,7,10-tetraazacyclododecane); using 1,4,7,10-tris(t-butoxycarbonyl)-1,4,7,10-tetraaza and potassium carbonate dissolved in a second Solvent, forming a third solution; adding benzyl bromoacetate to the third solution, after heating and refluxing, filtering and removing the solid and drying under reduced pressure, and separating and purifying by liquid chromatography by tube injection to obtain 1- (benzyl ester)-4,7,10 tris(t-butoxycarbonyl)-1,4,7,10-tetraazacyclododecane (1-(benzyl acetate)-4,7,10-Tris (tert-butoxycarbonylmethyl)
-1,4,7,10-tetraazacyclododecane); and 1-(benzyl ester)-4,7,10 tris(t-butoxycarbonyl)-1,4,7,10-tetraazacyclotetradecene The alkane is dissolved in methanol, further added with a palladium-carbon catalyst (Pd/C), shaken under a hydrogen atmosphere, and concentrated by filtration to obtain 1-(acetic acid)-4,7,10 tris(t-butoxycarbonyl)- 1,4,7,10-tetraaza(1-(acetic acid)-4,7,10-Tris(tert-butoxycarbonylmethyl)
-1,4,7,10-tetraazacyclododecane), which is a DOTA derivative organic ligand.

S1~S6‧‧‧Steps

Figure 1 is a flow chart showing the steps of a preparation method of a preferred embodiment of the present invention.

For a better understanding and understanding of the features and advantages of the present invention, the preferred embodiments and the detailed description are described as follows:

Referring to FIG. 1, the present invention comprises the steps of preparing a DOTA derivative organic ligand:

Step S1: using 1,4,7,10-tetraaza and sodium acetate dissolved in a first solvent to form a first solution;
Step S2: adding butyl bromoacetate to the first solution to form a second solution;
Step S3: adding sodium hydrogencarbonate to the second solution to produce a precipitate, which is filtered and dried under reduced pressure to obtain 1,4,7,10-tris(t-butoxycarbonyl)-1,4. , 7,10-tetraaza;
Step S4: using 1,4,7,10-tris(t-butoxycarbonyl)-1,4,7,10-tetraaza and potassium carbonate dissolved in a second solvent to form a third solution;
Step S5: adding benzyl bromoacetate to the third solution, and heating and refluxing, removing solids by filtration, drying under reduced pressure, and separating and purifying by liquid chromatography to obtain 1-(benzyl ester)-4,7. 10 tris(t-butoxycarbonyl)-1,4,7,10-tetraazacyclododecane; and step S6: using 1-(benzyl ester)-4,7,10 tris (third butoxide) The carbonyl group-1,4,7,10-tetraazacyclododecane is dissolved in methanol, further added with a palladium carbon catalyst, shaken under a hydrogen atmosphere, and concentrated by filtration to obtain 1-(acetic acid)-4. 7,10 tris(t-butoxycarbonyl)-1,4,7,10-tetraaza, which is a DOTA derivative organic ligand.

The preparation method disclosed in the present invention can be referred to the following formula 1, and can be summarized as follows: first, the starting material 1,4,7,10-tetraaza (compound (1)), sodium acetate and bromoacetic acid are third. The butyl ester is reacted in a first solvent, that is, N,N-dimethylacetamid, to obtain 1,4,7,10-tris(t-butoxycarbonyl)-1. , 4,7,10-tetraaza (compound (2)). Compound (2) is reacted with benzyl bromoacetate in a second solvent, that is, in anhydrous acetonitrile to give 1-(benzyl ester)-4,7,10 tris(t-butoxycarbonyl)-1,4,7 , 10-tetraazacyclododecane (compound (3)). Hydrogenation of compound (3) to obtain 1-(acetate)-4,7,10 tris(t-butoxycarbonyl)-1,4,7,10-tetraaza (compound (4)), It is an organic ligand for the DOTA derivative, abbreviated as DOTA-tris ( ^t Bu ester).
(Formula 1)

Based on the foregoing steps, in an operation example, the actual operation process and data analysis of the present invention are as follows:

Obtainment of Compound (1): The present invention is a 1,4,7,10-tetraaza complex having the structure of the following formula 2 from Shanghai Zillionaire Chemicals Inc.;
(Formula 2)

The analysis data is:
IR: ν _NH = 3300 cm ^-1 .
¹ H NMR (DMSO-d ₆ ): δ 2.68 (s, 12H, C ₁ H ₂ , C ₂ H ₂ , C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ ).
¹³ C NMR (DMSO-d ₆ ): δ 45.7 ( C ₁ H ₂ , C ₂ H ₂ , C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ ).
ESI-MS: m/z 174 (M) ⁺ .

Preparation of Compound (2): Compound (1) (2 g, 11.62 mmol), sodium acetate (2.85 g, 34.8 mmol) was dissolved in N,N-dimethylacetamide (DMA) in a 500 ml round bottom flask. , 25mL). Add N,N-dimethylacetamide (10 mL) to a third butyl bromoacetate (6.79 g, 34.82 mmol) under ice bath at 0 ° C, and react at room temperature for 5 days. After the reaction, pour 125 ml of water. At this time, the reaction will be a yellowish solution, and then slowly add sodium bicarbonate, the reaction will be found to have a white precipitate, the precipitate is filtered, the precipitate is dissolved in 150 mL of chloroform, and water (3 × 100 mL ) Wash and discard the water phase. The organic phase was dried over (Na ₂ SO ₄₎ and concentrated under reduced pressure after dried, and finally re-crystallized with diethyl ether, available as a white solid of compound (2) (4.1g, 78% ). It has the structure of the following formula 3:
(Formula 3)

The analysis data is:
IR: ν _NH = 3450 cm ^-1 , ν _CH = 2925 cm ^-1 , ν _CH = 2853 cm ^-1 , ν _{C = O} = 1736 cm ^-1 , ν _{C = O} = 1720 cm ^-1 .
¹ H NMR (CDCl ₃ ): δ 9.5 (s, br, N H ), 3.30 (s, 6H, C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ ), 3.21 (s, 2H, C ₁ H ₂ , C ₈ H ₂ ), 3.00 (m, 2H, C ₂ H ₂ , C ₇ H ₂ ), 2.81-2.80 (m, 12H, C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ ), 1.37 (s, 27H, C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H ₃ , C ₁₈ H _3, C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₃ H ₃ , C ₂₄ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ .
¹³ C NMR (CDCl ₃ ): δ 170.5 , 169.6 ( C ₁₀ O, C ₁₆ O, C ₂₂ O), 81.7, 81.6 ( C ₁₁ , C ₁₇ , C ₂₃ ), 58.1 ( C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ ), 51.2 ( C ₂ H ₂ , C ₇ H ₂ ), 49.1 ( C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ ), 47.4 ( C ₁ H ₂ , C ₈ H ₂ ), 28.2 ( C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H _{3 ,} C ₁₈ H ₃ , C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ , C ₂₆ H ₃ ).
MS: m/z 515 (M ⁺ +1).

Preparation of Compound (3): Compound (2) (1 g, 1.9 mmol) and potassium carbonate (0.54 g, 3.8 mmol) were dissolved in anhydrous acetonitrile (50 ml). A solution of benzyl bromoacetate (0.46 g, 1.9 mmol) in dry EtOAc (10 mL). The mixture was heated under reflux at 85 ° C for 48 hours, and the solid was removed by filtration. The filtrate was concentrated under reduced pressure and purified by column chromatography (SiO ₂ , CHCl ₃ /CH ₃ OH = 10 / 0.5). The compound (3) (0.66 g, 52%) was obtained as a brown oil. It has the structure of the following formula 4:
(Formula 4)

The analysis data is:
^{_{IR: ν NH = 3450 cm -1}} , ν CH = 2925 cm -1, ν CH = 2853 cm -1, ν C = O = 1736 cm-1, ν C = O = 1720cm -1, ν Ph = 1460cm - ¹ .
¹ H NMR (CDCl ₃ ): δ 7.38-7.28 (m, 5H, Ph-H), 5.13 (s, H, C ₂₈ H ₂ ), 3.3-2.1 (m, 24H, C ₁ H ₂ , C ₂ H ₂ , C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ , C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ , C ₂₆ H ₂ ), 1.41 (s, 27H, C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H ₃ , C ₁₈ H ₃ , C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ , C ₂₆ H ₃ ).
¹³ C NMR (CDCl ₃ ): δ 174.1 , 173.5, 173.4 ( C ₁₀ O, C ₁₆ O, C ₂₂ O, C ₂₇ O), 135.6 (C ₂₉ H ₁ ), 129.15 (C ₃₀ H ₁ ), 129.13 (C ₃₄ H ₁ ), 128.9 ( C ₃₁ H ₁ ), 128.7 ( C ₃₃ H ₁ ) , 127.5 ( C ₃₁ H ₁ ), 82.5, 82.2 ( C ₁₁ , C ₁₇ , C ₂₃ ), 67.4 ( C ₂₈ H ₂ ), 65 ( C ₁ H ₂ , C ₂ H ₂ , C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ ), 56.2 ( C ₂₆ H ₂ ), 56.1 ( C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ ), 28.2 ( C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H ₃ , C ₁₈ H ₃ , C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ , C ₂₆ H ₃ ).
ESI-MS: m/z 662 (M) ⁺ .

Preparation of Compound (4): Compound (3) (333 mg, 0.5 mmol) was dissolved in 95% methanol (10 mL), and then 0.1 g of 10% palladium carbon catalyst was added. Under a 50 psi hydrogen atmosphere at room temperature, shake to the next day. After filtration through a Celite 545-br. funnel, EtOAc (EtOAc)

The analysis data is:
IR: ν _OH = 3500 cm ^-1 , ν _CH = 2925 cm ^-1 , ν _CH = 2853 cm ^-1 , ν _{C = O} = 1710 cm ^-1 .
¹ H-NMR (CDCl ₃ ): δ 3.8-2.7 (m, 24H, C ₁ H ₂ , C ₂ H _{2 ,} C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ , C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ , C ₂₆ H ₂ ), 1.41 (s, 27H, C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H ₃ , C ₁₈ H ₃ , C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ , C ₂₆ H ₃ ).
¹³ C-NMR (CDCl ₃ ): δ 175 ( C ₂₈ O), 173 ( C ₁₀ O , C ₁₆ O, C ₂₂ O), 83 ( C ₁₁ , C ₁₇ , C ₂₃ ), 58.2 ( C ₂₇ H ₂ ) , 56 ( C ₉ H ₂ , C ₁₅ H ₂ , C ₂₁ H ₂ ), 52 ( C ₁ H ₂ , C ₂ H ₂ , C ₃ H ₂ , C ₄ H ₂ , C ₅ H ₂ , C ₆ H ₂ , C ₇ H ₂ , C ₈ H ₂ ), 28.6 ( C ₁₂ H ₃ , C ₁₃ H ₃ , C ₁₄ H ₃ , C ₁₈ H ₃ , C ₁₉ H ₃ , C ₂₀ H ₃ , C ₂₄ H ₃ , C ₂₅ H ₃ , C ₂₆ H ₃ ).
ESI-MS: m/z 573 (M) ⁺ .

In addition, in the preparation process, the color development of the thin layer chromatography sheet can be used as a basis for discriminating the difference between the compound (3) and the compound (4), and the reaction completion time can be judged; The discrimination rate (the difference in residence time is clarified by the extract), and the complete reaction of the compound (2) with nihydrin is confirmed, and the purity of the compound (3) can be more precisely controlled.

The method for preparing an organic ligand of a DOTA derivative disclosed by the present invention provides a method having a significantly lower cost advantage, and preparing a DOTA derivative DOTA-tris ( ^t Bu ester) for use as a contrast agent precursor, After coupling with 6-(2-nitro-1H-imidazol-1-yl)hexan-1-amine, the hypoxic tissue contrast agent DOTA-Ni is formed. The preparation method of the invention has the advantages of low cost and high purity, and has high practicality and economic value.

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.

S1~S6‧‧‧Steps

Claims (7)

A method for preparing an organic ligand of a DOTA derivative, wherein the organic ligand of the DOTA derivative comprises a chemical structure:


The system contains the steps:
Using 1,4,7,10-tetraaza and sodium acetate dissolved in a first solvent to form a first solution;
Adding butyl bromoacetate to the first solution to form a second solution;
Sodium bicarbonate is added to the second solution to produce a precipitate which is filtered and dried under reduced pressure to give 1,4,7,10-tris(t-butoxycarbonyl)-1,4,7. 10-tetrazole;
Using 1,4,7,10-tris(t-butoxycarbonyl)-1,4,7,10-tetraaza and potassium carbonate dissolved in a second solvent to form a third solution;
Benzyl bromoacetate is added to the third solution, and after heating and refluxing, the solid is removed by filtration, dried under reduced pressure, and purified by column chromatography by liquid chromatography to obtain 1-(benzyl ester)-4,7,103 ( Third butoxycarbonyl)-1,4,7,10-tetraazacyclododecane; and 1-(benzyl ester)-4,7,10 tris(t-butoxycarbonyl)-1, 4,7,10-tetraazacyclododecane is dissolved in methanol, added with Pd/C, shaken under a hydrogen atmosphere, and concentrated by filtration to obtain 1-(acetic acid)-4,7,10 three (the first Tributoxycarbonyl)-1,4,7,10-tetraaza, which is a DOTA derivative organic ligand. The method for preparing a DOTA derivative organic ligand according to claim 1, wherein the first solvent is N,N-dimethylacetamide (DMA). The method for preparing a DOTA derivative organic ligand according to claim 1, wherein the second solvent is anhydrous acetonitrile. The method for preparing an organic ligand of a DOTA derivative according to claim 1, wherein the third butyl bromoacetate is dissolved in the first solvent before being added to the first solution. The method for preparing an organic ligand of a DOTA derivative according to claim 1, wherein benzyl bromoacetate is first dissolved in the second solvent before adding the benzyl bromoacetate to the third solution. The method for preparing an organic ligand for a DOTA derivative as described in claim 1, wherein the precipitate is washed with chloroform before filtration. The preparation method of the DOTA derivative organic ligand according to claim 1, wherein the heated reflux is heated and refluxed at 85 ° C for 48 hours in the step of adding benzyl bromoacetate to the third solution.