Polycyclic compound as well as preparation method and application thereof

Abstract

The invention provides a polycyclic compound and a preparation method and application thereof, the compound has a structure shown in the following formula: R1 and R2 are respectively and independently selected from at least one of H, methyl and ethyl, R3 is selected from at least one of ethyl, propyl and isopropyl, and n is an integer of 1-4. The compound has near-infrared two-region fluorescence activity. # imgabs0 #

Description

Technical Field

[0001] This application relates to the field of biochemical analysis technology. Specifically, it relates to polycyclic compounds, their preparation methods and uses. More specifically, it relates to a near-infrared second-window fluorescent dye based on azulene, its preparation method and application. Background Art

[0002] Near-infrared second-window fluorescence imaging is a technology that uses near-infrared second-window light sources (wavelengths in the range of 1000 - 1700 nm) for fluorescence imaging. Due to the longer wavelength, it has lower photon scattering and weaker autofluorescence of tissues, thus greatly improving the detection depth, resolution and sensitivity of fluorescence imaging. So far, various fluorophores have been reported for near-infrared second-window fluorescence imaging, but fewer are used for bone imaging. However, most of the current near-infrared second-window fluorescent dyes have disadvantages such as difficult synthesis and difficult wavelength regulation due to their complex structures.

[0003] Therefore, it is of great significance to develop a small-molecule fluorescent probe with simple synthesis and flexible wavelength regulation for near-infrared second-window emission for bone imaging. Summary of the Invention

[0004] In view of the above problems, this application provides a polycyclic compound, its preparation method and uses, which can simply obtain an azulene-based polycyclic compound with near-infrared second-window fluorescence activity and has a high yield.

[0005] In one aspect of this application, a polycyclic compound based on azulene is proposed. The compound has the structure shown by the following formula:

[0006]

[0007] Wherein, R1 and R2 are each independently selected from at least one of H, methyl, and ethyl, R3 is selected from at least one of ethyl, propyl, and isopropyl, and n is an integer from 1 to 4.

[0008] This compound has good near-infrared second-window fluorescence characteristics and high structural symmetry, which is convenient for preparation and synthesis.

[0009] According to an embodiment of this application, R1 is H, methyl or ethyl, R2 is H, methyl or ethyl, R3 is propyl or isopropyl, and n is 1, 2, or 3.

[0010] According to an embodiment of this application, the compound has the structure shown by the following formula:

[0011]

[0012] In another aspect of the present application, a method for preparing the above-mentioned polycyclic compound is provided. The method includes heating a ketone compound and a first reactant in an organic solvent to obtain an intermediate product, and then reacting the intermediate product with a raw material containing azulene in an acid and an organic solvent at room temperature. Among them, the ketone compound is a saturated cyclic ketone compound, the first reactant includes DMF and POCl3, and the raw material containing azulene includes guaiazulene. This method can simply obtain the aforementioned polycyclic compound with a relatively high yield.

[0013] According to an embodiment of the present application, the saturated cyclic ketone compounds include cyclopentanone, cyclohexanone, and cycloheptanone, the acid is perchloric acid, and the organic solvents include dichloromethane and anhydrous methanol.

[0014] According to an embodiment of the present application, the molar ratio of the saturated cyclic ketone compound to POCl3 is 1:2, the molar ratio of the intermediate product to guaiazulene is 1:2, and the molar volume ratio of the intermediate product to the acid is 1 mmol:0.5 mL.

[0015] According to an embodiment of the present application, the reaction temperature is 20 - 60 °C, the reaction time is 2 h - 12 h, and the reaction is carried out in an inert atmosphere.

[0016] In yet another aspect of the present application, the use of the aforementioned polycyclic compound in near-infrared second-region imaging is provided. Description of the Drawings

[0017] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present application. Moreover, in all the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0018] Figure 1 are the absorption and emission spectra of the compounds prepared in Examples 1 - 3 of the present application;

[0019] Figure 2 are the absorption and emission spectra of the compounds prepared in Examples 1 - 3 of the present application showing the formation of H-aggregates and J-aggregates in different ratios of PBS and acetonitrile;

[0020] Figure 3 is the whole-body skeletal imaging map of the compound prepared in Example 2 of the present application 12 hours after intravenous injection into the mouse tail vein. Detailed Embodiments

[0021] The embodiments of the technical solution of the present application will be described in detail below with reference to the accompanying drawings. The following embodiments are only used to illustrate the technical solution of the present application more clearly, so they are only examples and cannot be used to limit the protection scope of the present application.

[0022] In one aspect of the present application, a polycyclic compound based on azulene is proposed. The compound has the structure shown by the following formula:

[0023]

[0024] Wherein, R1 and R2 are each independently selected from at least one of H, methyl, and ethyl, R3 is selected from at least one of ethyl, propyl, and isopropyl, and n is an integer from 1 to 4.

[0025] This compound has good fluorescence characteristics in the second near-infrared region, and has high structural symmetry, which is convenient for preparation and synthesis.

[0026] Specifically, the two R1s in this compound are located at positions symmetrical with respect to the chloro-substituted alkene ring, and the two R1s can be the same or different. Similarly, the positions of the two R2s are also symmetrical with respect to the chloro-substituted alkene ring, and the two R1s can be the same or different; the positions of the two R3s are also symmetrical with respect to the chloro-substituted alkene ring, and the two R3s can be the same or different.

[0027] According to an embodiment of the present application, R1 is H, methyl or ethyl, R2 is H, methyl or ethyl, R3 is propyl or isopropyl, and n is 1, 2, or 3. That is: both R1s are H, methyl or ethyl, both R2s are H, methyl or ethyl, and both R3s are propyl or isopropyl.

[0028] According to some specific embodiments of the present application, the compound has the structure shown by the following formula:

[0029]

[0030] Wherein, n = 1, 2 or 3. That is to say, the chloro-containing alkene ring can be chloro-substituted cyclopentene, cyclohexene or cycloheptene.

[0031] In some specific embodiments, the polycyclic compound can be the compounds shown by Formula I - Formula III:

[0032]

[0033] In another aspect of the present application, a method for preparing the above-mentioned polycyclic compound is proposed. The method includes: heating a ketone compound and a first reactant in an organic solvent to obtain an intermediate product, and reacting the intermediate product with a raw material containing azulene in an acid and an organic solvent at room temperature to obtain the product. Among them, the ketone compound is a saturated cyclic ketone compound, the first reactant includes DMF and POCl3, and the raw material containing azulene includes guaiazulene. This method can simply obtain the aforementioned polycyclic compound with a high yield.

[0034] According to an embodiment of the present application, the saturated cyclic ketone compound includes cyclopentanone, cyclohexanone, and cycloheptanone, the acid is perchloric acid, and the organic solvent includes at least one of dichloromethane and anhydrous methanol.

[0035] According to an embodiment of the present application, the molar ratio of the saturated cyclic ketone compound to POCl3 is 1:2, the molar ratio of the intermediate product to guaiazulene is 1:2, the molar volume ratio of the intermediate product to the acid is 1 mmol:0.5 mL, the reaction temperature is 20-60 °C, the reaction time is 2 h-12 h, and the reaction is carried out in an inert atmosphere. Thus, the above polycyclic compound can be simply obtained.

[0036] In some specific embodiments, the above method may specifically include:

[0037] Preparing the compound shown in Formula I: Heating cyclopentanone, DMF, and POCl3 reactants in an organic solvent to obtain an intermediate compound, and stirring the intermediate compound and guaiazulene at room temperature in the presence of an acid and an organic solvent.

[0038] Preparing the compound shown in Formula II: Heating cyclohexanone, DMF, and POCl3 reactants in an organic solvent to obtain an intermediate compound, and stirring the intermediate compound and guaiazulene at room temperature in the presence of an acid and an organic solvent.

[0039] Preparing the compound shown in Formula III: Heating cycloheptanone, DMF, and POCl3 reactants in an organic solvent to obtain an intermediate compound, and stirring the intermediate compound and guaiazulene at room temperature in the presence of an acid and an organic solvent.

[0040] In yet another aspect of the present application, the present application proposes the use of the aforementioned polycyclic compound in near-infrared second-region imaging.

[0041] Specifically, the aforementioned polycyclic compound can regulate the wavelength and aggregation behavior by adjusting the size of the cycloalkene, and has a relatively wide application prospect in the near-infrared second-region imaging of fluorescent dyes.

[0042] For example, specifically, the aforementioned compound, especially the compound shown in Formula II, can form J-aggregates by being encapsulated with DSPE-PEG2000, and at the same time, near-infrared second window fluorescence imaging can be performed.

[0043] The compounds and their preparation methods proposed in this application have the following advantages:

[0044] 1) By regulating the size of the cycloalkene, the absorption wavelength and emission wavelength can be adjusted.

[0045] 2) It has good chemical stability and can be used for long-term in vivo imaging.

[0046] 3) The emission wavelength reaches the second near-infrared region, which can effectively reduce the influence of autofluorescence background signals in vivo;

[0047] 4) After 12 hours of tail vein injection, the bones of mice can be significantly illuminated, indicating that this fluorescent probe can be used for bone imaging research.

[0048] The methods and systems described above in this application will be described in detail below through specific examples. In the following examples, unless otherwise specified, the reagents are all commercially available.

[0049] Example 1:

[0050] The compound shown in Formula I was prepared according to the following synthetic route:

[0051]

[0052] Under N2 protection, 1 mL of DMF was placed in 1 mL of dichloromethane, and the mixture was stirred for 10 min in an ice bath at 0 °C. 0.5 mL of POCl3 was gradually added dropwise to the above solution, and then the temperature was raised to room temperature and stirred for 30 min. Cyclopentanone (5 mmol) dissolved in 2 mL of dichloromethane was added dropwise to the above reaction system, and the mixture was heated under reflux at 50 °C overnight. After the reaction was completed, it was quenched with ice water, precipitated in water as a yellow powder, and purified by washing with cold ether and ice water. A yellow solid (85%) intermediate was obtained. Under N2 protection, compound 1 (0.4 mmol) and guaiazulene (0.2 mmol) were dissolved in anhydrous methanol, 0.5 mL of perchloric acid was added, and the mixture was stirred at room temperature for 10 min. After the reaction was completed, it was precipitated with ether to form a black solid, and purified by silica gel column chromatography (dichloromethane:methanol = 10:1). The fluorescent dye compound of Formula I was obtained (yield 67%).

[0053] The product structure was confirmed as follows:

[0054] 11H NMR (700 MHz, CD2Cl2) δ 8.78 (s, 2H), 8.32 (s, 2H), 8.06 (s, 2H), 7.85 (dd, J = 10.9, 1.5 Hz, 2H), 7.75 (d, J = 11.0 Hz, 2H), 3.43 (s, 4H), 3.33 (s, 6H), 3.27 (dt, J = 13.7, 6.9 Hz, 2H), 2.66 (s, 6H), 1.46 (d, J = 6.9 Hz, 12H).

[0055] 13 13C NMR (176 MHz, CD2Cl2) δ 158.86, 155.11, 150.94, 149.13, 144.83, 139.70, 139.49, 138.98, 138.62, 136.11, 135.55, 135.00, 131.42, 38.55, 30.79, 29.36, 23.88, 13.33.

[0056] High-resolution mass spectrometry: C 37 H 40 Cl, [M] + , calculated value is 519.2819; measured value is 519.2813.

[0057] Example 2:

[0058] The compound shown in Formula II was prepared according to the following synthetic route:

[0059]

[0060] The remaining operations were the same as in Example 1, except that cyclohexanone was used as the starting material.

[0061] The structure of the product was confirmed as follows:

[0062] 1 1H NMR (700 MHz, CDCl3) δ 9.04 (s, 2H), 8.25 (s, 2H), 7.98 (s, 2H), 7.85 (d, J = 11.0 Hz, 2H), 7.80 (d, J = 11.0 Hz, 2H), 3.27 (s, 6H), 3.26 - 3.21 (m, 2H), 3.14 (s, 4H), 2.61 (s, 6H), 2.13 - 2.06 (m, 2H), 1.42 (d, J = 6.9 Hz, 12H).

[0063] 1313C NMR (176 MHz, CDCl3) δ 155.35, 155.20, 150.98, 148.99, 145.99, 142.38, 139.62, 139.34, 139.20, 135.82, 134.94, 132.46, 130.70, 38.58, 30.39, 29.74, 24.23, 22.31, 13.61.

[0064] High resolution mass spectrometry: C 38 H 42 Cl, [M] + , calculated value is 533.2975, measured value is 533.2969.

[0065] Example 3:

[0066] The compound shown in Formula III was prepared according to the following synthetic route:

[0067]

[0068] The remaining operations were the same as in Example 1, except that cycloheptanone was used as the starting material.

[0069] The structure confirmation of the product is as follows:

[0070] 1 1H NMR (700 MHz, CDCl3) δ 9.05 (s, 2H), 8.28 (d, J = 1.1 Hz, 2H), 7.94 (s, 2H), 7.87 (dd, J = 25.0, 11.0 Hz, 2H), 3.27 (d, 6H), 3.25 (d, 2H), 3.13 (s, 4H), 2.62 (s, 6H), 2.09 (s, 4H), 1.43 (d, J = 6.9 Hz, 12H).

[0071] 13 13C NMR (176 MHz, CDCl3) δ 158.36, 155.44, 153.69, 151.02, 149.07, 146.18, 145.43, 139.72, 139.45, 138.85, 135.87, 134.77, 129.94, 38.60, 30.28, 29.84, 24.99, 24.23, 23.72, 13.64.

[0072] High resolution mass spectrometry: C39H44Cl, [M] + , 547.3132, measured value is 547.3124.

[0073] The absorption and emission spectra of the compounds prepared in Examples 1 - 3 were tested in chloroform:

[0074] The fluorescent dyes (compounds shown in Formulas I-III) were respectively added into test tubes, and then an appropriate volume of chloroform solution was added to make the final fluorophore concentration 10 μM. The absorption spectra of the solutions were measured on an ultraviolet spectrophotometer, and their fluorescence spectra were measured on a fluorescence spectrophotometer. With 808 nm selected as the excitation wavelength, the ultraviolet absorption (see (a) in Figure 1 ) and fluorescence emission spectra (see (b) in Figure 1 ) were obtained respectively. As can be seen from (a) in Figure 1 , the three fluorescent dye compounds can emit strong fluorescence in an organic environment, and the emission wavelengths gradually increase, being 965 nm, 985 nm, and 1025 nm respectively.

[0075] Absorption and emission spectra tests of the compounds prepared in Examples 1-3 in different ratios of PBS and acetonitrile:

[0076] The fluorescent dyes (compounds shown in Formulas I-III) were respectively added into test tubes, and then an appropriate volume of PBS and acetonitrile solutions (volume ratios were 99%, 90%, 60%, 30%, and 0% respectively) were added to make the final fluorophore concentration 10 μM. The absorption spectra of the solutions were measured on an ultraviolet spectrophotometer, and their fluorescence spectra were measured on a fluorescence spectrophotometer. With 808 nm selected as the excitation wavelength, the ultraviolet absorption and fluorescence emission spectra were obtained respectively (see Figure 2 ). As can be seen from the ultraviolet absorption spectrum of the compound of Formula I in (a) in Figure 2 and the fluorescence emission spectrum of the compound of Formula I in (b), it forms an H aggregate in 99% PBS, with an absorption peak at 752 nm and almost no fluorescence generated. As can be seen from the ultraviolet absorption spectrum of the compound of Formula II in (c) in Figure 2 and the fluorescence emission spectrum of the compound of Formula II in (d), the compound of Formula II forms a J aggregate in 99% PBS, with an absorption peak at 1162 nm and an emission peak at 1170 nm. As can be seen from the ultraviolet absorption spectrum of the compound of Formula III in (e) in Figure 2 and the fluorescence emission spectrum of the compound of Formula III in (f), the compound of Formula III forms a J aggregate in 99%, with an absorption peak at 1145 nm and an emission peak at 1170 nm.

[0077] Whole body bone imaging test 12 hours after tail vein injection in mice:

[0078] 200 μL of the liposome of the fluorescent probe compound of Formula II was injected into the tail vein of mice at an injection concentration of 500 μM. The whole body of the mice was irradiated with an 808 nm laser, and a clear and high-resolution imaging map could be observed using a 1150 nm long-pass filter (see Figure 3Supine (lying on the back) and Prone (lying face down), and are mainly distributed in the liver area and the bone area, indicating that it can be well applied to in vivo imaging of mouse bones in the second near-infrared region.

[0079] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" and any variations thereof in the specification and claims of this application and the above description of the drawings are intended to cover non-exclusive inclusion.

[0080] Reference to "embodiment" herein means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of this application. The phrase appears in various places in the specification and does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art will explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0081] In the description of the embodiments of this application, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " herein generally represents an "or" relationship between the associated objects before and after.

[0082] Unless otherwise specified, the terms used in this application have the well-known meanings commonly understood by those skilled in the art. Unless otherwise specified, the numerical values of the various parameters mentioned in this application can be measured by various commonly used measurement methods in the art (for example, they can be tested according to the methods given in the embodiments of this application).

[0083] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit them; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of this application, and they should all be covered within the scope of the claims and the specification of this application. In particular, as long as there is no structural conflict, the various technical features mentioned in each embodiment can be combined in any way. This application is not limited to the specific embodiments disclosed herein, but includes all technical solutions that fall within the scope of the claims.

Claims

1. An azulene-based polycyclic compound, characterized in that, The compound has the structure shown by the following formula: wherein, R1 and R2 are each independently selected from at least one of H, methyl, and ethyl, and R3 is selected from at least one of ethyl, propyl, and isopropyl. n is an integer from 1 to 4.

2. The polycyclic compound according to claim 1, characterized in that, R1 is H, methyl or ethyl, R2 is H, methyl or ethyl, R3 is propyl or isopropyl, n is 1, 2, or 3.

3. The polycyclic compound according to claim 1 or 2, characterized in that, The compound has the structure shown by the following formula:

4. A method for preparing the polycyclic compound according to any one of claims 1-3, characterized in that, The method includes: heating a ketone compound and a first reactant in an organic solvent to obtain an intermediate product, and reacting the intermediate product with a raw material containing azulene in an acid and an organic solvent at room temperature. wherein, the ketone compound is a saturated cyclic ketone compound, the first reactant includes DMF and POCl3, and the raw material containing azulene includes guaiazulene.

5. The method according to claim 4, wherein The saturated cyclic ketone compounds include cyclopentanone, cyclohexanone, and cycloheptanone, the acid is perchloric acid, and the organic solvents include dichloromethane and anhydrous methanol.

6. The method according to claim 4, characterized in that, The molar ratio of the saturated cyclic ketone compound to POCl3 is 1:2, the molar ratio of the intermediate product to guaiazulene is 1:2, and the molar volume ratio of the intermediate product to the acid is 1 mmol:0.5 mL.

7. The method according to any one of claims 4 to 6, characterized in that: The reaction temperature is 20-60 °C, the reaction time is 2 h-12 h, and the reaction is carried out in an inert atmosphere.

8. Use of the polycyclic compound according to any one of claims 1-3 in second near-infrared region imaging.

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