Carborane cage boron free radical as well as preparation method and application thereof

Abstract

The invention relates to the technical field of organic electrochemical synthesis, and discloses a carborane cage boron free radical and a preparation method and application thereof.The structural formula of the carborane cage boron free radical is shown in the formula I. The preparation method has the advantages that in-situ generation of boron free radicals under the electrochemical condition is achieved for the first time; a B-N bond of diazo-carborane tetrafluoroborate is electrochemically reduced to generate a boron center free radical with reaction activity, the free radical can efficiently initiate a series cyclization reaction of 2-isocyano aryl sulfide, and a carborane benzothiazole skeleton is constructed in one step.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of organic electrochemical synthesis, and particularly relates to a carborane cage boron radical and a preparation method and application thereof. BACKGROUND

[0002] Neutral carboranes are a class of electron delocalized (non-classical bonding) clusters composed of boron, carbon and hydrogen atoms, consisting of 2 CH vertices and 10 BH vertices. There are 6 adjacent atoms around each boron or carbon atom, including 5 skeletal atoms and 1 hydrogen atom. According to the different positions of the two carbon atoms in the skeleton, neutral icosahedral closed carboranes can be divided into o-carborane (1,2-C2B 10 H 12 ), m-carborane (1,7-C2B 10 H 12 ) and p-carborane (1,12-C2B 10 H 12 ) three isomers according to the different positions of carbon in the molecule. Among the carborane family, o-carborane has been most widely used due to its cheap commercial availability (Carboranes, 3rd ed. Elsevier, 2016).

[0003] In the carborane molecule, the total number of valence electrons is 50, of which 24 valence electrons are used to form 2 C-H and 10 B-H σ bonds, and the remaining 26 electrons are delocalized in the icosahedral skeleton, forming three-center two-electron (3c-2e) bonds through p orbitals tangent to the polyhedron and sp hybridization orbitals pointing to the center of the polyhedron, as shown below. The total number of electrons delocalized on the three-dimensional skeleton of carborane meets the "4n+2" Hückel rule, and therefore carborane has high three-dimensional aromaticity and is considered as a three-dimensional analogue of benzene.

[0004]

[0005] Carboranes have attracted considerable interest in various fields due to their unique properties, including excellent thermal / chemical stability, special sigma conjugation effect, high electron deficiency, and spherical hydrophobic surface. For example, they are used as boron carriers in boron neutron capture therapy (Chem. Rev., 2011, 111, 7035-7062), as building blocks for nanomaterials and optoelectronic functional materials (Chem. Soc. Rev., 2016, 45, 5147-5173), and as multifunctional ligands in metal-organic / coordination chemistry (Coord. Chem. Rev., 2002, 231, 23-46). Therefore, the development of carborane-containing molecules with potential applications and the related functional synthesis techniques have attracted much attention.

[0006] Boron-centered radical chemistry, especially Lewis base-coordinated boron radicals, as an important intersection of main group element chemistry and synthetic methodology, has shown irreplaceable value in the construction of complex molecular skeletons due to their unique electron-deficient properties and spatial tunability (Chem. Soc. Rev. 2021, 50, 13129-13188). These active intermediates exhibit excellent performance in key transformations such as cross-coupling and asymmetric borohydration, but their development still faces major bottlenecks. Compared with mature carbon radical chemistry systems, the generation method of neutral boron radicals is extremely limited. The existing technology mainly relies on the thermal / photochemical hydrogen abstraction process of N-heterocyclic carbene-borane (NHC-BH3) systems, which severely limits their application in complex molecular synthesis (J. Am. Chem. Soc. 2015, 137, 8617-8622). It is particularly worth noting that the hypervalent boron radical in the carborane skeleton opens up a new direction for boron radical chemistry due to its unique icosahedral symmetry, three-dimensional electron delocalization system, and excellent chemical stability. However, the existing synthesis methods generally rely on excessive toxic radical initiators or redox reagents, which not only have poor atom economy, but also seriously hinder their large-scale application.

[0007] Therefore, the prior art still needs to be improved and developed. SUMMARY

[0008] In view of the deficiencies of the prior art described above, the purpose of the present application is to provide a carborane cage boron radical and a preparation method and application thereof, and to provide a method for preparing a boron radical.

[0009] The technical solutions of the present application are as follows:

[0010] In a first aspect of the present application, a carborane cage boron radical is provided, and the structural formula of the carborane cage boron radical is shown as formula 1:

[0011]

[0012] wherein, is C, is B;

[0013] o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B is selected from any B vertex;

[0014] R 1 and R 2 are each selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, substituted or unsubstituted aryl of 6-20 carbons;

[0015] when o is selected from CR 2 , R 1 and R 2 may optionally be linked to form a ring.

[0016] In a second aspect of the present application, there is provided a method for preparing the carborane cage boron radical as described above, the method comprising the steps of:

[0017] stirring a compound of formula 2 with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound of formula 3;

[0018] subjecting the compound of formula 3 to electrochemical conditions to obtain the compound of formula 1, which is the carborane cage boron radical;

[0019] The synthetic route of the above reaction is as follows:

[0020]

[0021] Preferably, the first temperature is room temperature, the first predetermined time is 1-2h; the electrochemical conditions are: working current is 4-15mA, electrolyte is tetrabutylammonium hexafluorophosphate or tetrabutylammonium tetrafluoroborate, solvent is acetonitrile, tetrahydrofuran or hexafluoroisopropanol; the molar ratio of the compound of formula 2 to nitro tetrafluoroboric acid is (1-1.2):1.

[0022] Preferably, the electrochemical conditions are: the electrochemical reaction cell is a diaphragmless electrolytic cell, the electrode material of the cathode is graphite, and the electrode material of the anode is graphite.

[0023] In a third aspect of the present application, there is provided a method for capturing the carborane cage boron radical, the method comprising the steps of:

[0024] To the compound of formula 1, a radical trap 1,1-diphenylethylene is added, and the reaction is stirred at a second temperature for a second predetermined time under the electrochemical conditions described above to obtain a compound of formula 4;

[0025] The reaction scheme of the above reaction is as follows:

[0026]

[0027] Preferably, the second temperature is room temperature, the second predetermined time is 1-2h; and the molar ratio of the compound of formula 1 to 1,1-diphenylethylene is (1-1.1):1.

[0028] In a fourth aspect, the present application provides a carborane benzothiazole derivative, the general structure of which is shown in formula 5:

[0029]

[0030] wherein, is C, is B;

[0031] o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B in B-NH2 is selected from any one of the B vertices;

[0032] R 1 and R 2 are each selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, or substituted or unsubstituted aryl of 6-20 carbons;

[0033] when o is selected from CR 2 , R 1 and R 2 may optionally be linked to form a ring;

[0034] R 3 , R 4 , R 5 , R 6 are each selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, or substituted or unsubstituted aryl of 6-20 carbons;

[0035] X is selected from S, Se.

[0036] In a fifth aspect, the present application provides a preparation method of the above-mentioned carborane benzothiazole derivative, comprising the following steps:

[0037] stirring and reacting the compound shown in formula 2 with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound shown in formula 3;

[0038] stirring and reacting the compound shown in formula 3 and the compound shown in formula 6 under the above-mentioned electrochemical condition at the first temperature for a second predetermined time to obtain a compound shown in formula 5, i.e. the carborane benzothiazole derivative;

[0039] The synthetic route of the above-mentioned reaction is as follows:

[0040]

[0041] Preferably, the molar ratio of the compound shown in formula 2 to nitro tetrafluoroboric acid is (1-1.1) : 1; and the molar ratio of the compound shown in formula 2 to the compound shown in formula 6 is (1-2) : 1.

[0042] In a sixth aspect, the present application provides the application of the above-mentioned carborane benzothiazole derivative in the development of medicine, the creation of pesticide and the development of functional material.

[0043] Advantages:

[0044] 1. The present application realizes the in-situ generation of boron radical under electrochemical condition for the first time, generates a reactive boron center radical by electrochemical reduction of the B-N bond of diazo-carborane tetrafluoroborate, and efficiently initiates the tandem cyclization reaction of 2-isocyanaryl sulfide to construct the carborane benzothiazole skeleton in one step.

[0045] 2. The B(3)-ortho-carborane benzothiazole derivative provided by the present application has unique structure modifiability, can be diversified and functional group transformed through the cage-shaped carbon vertex, and expands the application potential.

[0046] 3, The preparation method adopted by the present application uses clean electric energy instead of chemical reducing agents, significantly improving the atomic economy of the reaction; the preparation method of the present application first realizes the reduction of the B-N bond of 3-diazo-o-carborane tetrafluoroborate to produce a boron-centered carborane radical at room temperature through electrochemical induction, and makes it undergo a radical tandem cyclization reaction with 2-isocyanaryl sulfide, realizing the efficient synthesis of B(3)-o-carborane benzothiazole derivatives; the preparation method provided by the present application can directly use air-stable 3-amino-o-carborane as a raw material to carry out one-pot reaction without pre-preparing 3-diazo-o-carborane tetrafluoroborate, greatly simplifying the process; the preparation method adopted by the present application has mild reaction conditions, simple operation, low cost, and has successfully realized the preparation of kilograms of scale, showing excellent industrial application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0047] Figure 1 The electrochemical reaction device in the preparation of the carborane cage boron radical and the carborane benzothiazole derivative provided by the present application.

[0048] Figure 2 The X-ray single crystal diffraction structure diagram of compound 1.

[0049] Figure 3 The X-ray single crystal diffraction structure diagram of compound 2.

[0050] Figure 4 The X-ray single crystal diffraction structure diagram of compound 11.

[0051] Figure 5 The X-ray single crystal diffraction structure diagram of compound 25. DETAILED DESCRIPTION

[0052] The present application provides a carborane cage boron radical and its preparation method and application. In order to make the purpose, technical scheme and effect of the present application more clear and explicit, the present application will be further described in detail. It should be understood that the specific examples described herein are only used to explain the present application and not to limit the present application.

[0053] Electrochemical synthesis as an important means of green chemistry, through the precise electron transfer process, has been successfully applied to the controlled generation and transformation of carbon, nitrogen, oxygen and other element-centered free radicals (Acc. Chem. Res. 2020, 53, 72-83). However, it is surprising that although electrochemical free radical chemistry has made great progress, there are still few reports on the electrochemical induction method of boron-centered free radicals. In the aspect of synthetic strategy, radical cascade reaction is favored due to its advantages of efficient construction of polycyclic system and simultaneous introduction of multi-functional groups. Among them, isocyanide compounds as excellent free radical acceptors, the imidoyl radical intermediates generated by them have become the core synthon for the construction of nitrogen-containing heterocycles, which has important value in drug molecule design (Angew. Chem., Int. Ed. 2018, 57, 5594-5619).

[0054] Based on this, the embodiment of the present application provides a carborane cage boron free radical, the structural formula of the carborane cage boron free radical is as shown in formula 1:

[0055]

[0056] Among them, C is; B is;

[0057] o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B is selected from any B vertex;

[0058] R 1 and R 2 are each selected from one independently selected from H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, substituted or unsubstituted aryl of 6-20 carbons;

[0059] When o is selected from CR 2 , R 1 and R 2 may be optionally connected to form a ring.

[0060] In this embodiment, "substituted or unsubstituted alkyl of 1-15 carbon atoms" includes straight chain alkyl and branched chain alkyl, the alkyl can be substituted alkyl of 1-15 carbon atoms or unsubstituted alkyl of 1-15 carbon atoms, when the alkyl is selected from substituted alkyl of 1-15 carbon atoms, the alkyl can be substituted by one or more selected from deuterium, halogen, unsubstituted alkyl of 1-15 carbon atoms, or unsubstituted aryl of 6-20 carbon atoms; preferably "substituted or unsubstituted alkyl of 1-10 carbon atoms", more preferably "substituted or unsubstituted alkyl of 1-5 carbon atoms". "Substituted or unsubstituted benzyl" can be substituted benzyl or unsubstituted benzyl, when selected from substituted benzyl, the benzyl can be substituted by one or more selected from deuterium, halogen, unsubstituted alkyl of 1-15 carbon atoms, or unsubstituted aryl of 6-20 carbon atoms. "Substituted or unsubstituted aryl of 6-20 carbon atoms" can be substituted aryl of 6-20 carbon atoms or unsubstituted aryl of 6-20 carbon atoms, when selected from substituted aryl of 6-20 carbon atoms, the aryl can be substituted by one or more selected from deuterium, halogen, unsubstituted alkyl of 1-15 carbon atoms, or unsubstituted aryl of 6-20 carbon atoms; preferably "substituted or unsubstituted aryl of 6-12 carbon atoms", more preferably a benzene ring. In addition, the same description appears again below, which is explained as described in this embodiment.

[0061] The present embodiment provides a preparation method of carborane cage boron radical, the preparation method comprises the following steps:

[0062] The compound shown in formula 2 is stirred with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound shown in formula 3;

[0063] The compound shown in formula 3 is obtained under electrochemical conditions to obtain a compound of formula 1, which is the carborane cage boron radical;

[0064] The synthesis route of the above reaction is as follows:

[0065]

[0066] In some embodiments, the above preparation method comprises the following steps:

[0067] Step S1, the compound shown in formula 2 and nitro tetrafluoroboric acid (NOBF4) are stirred at a first temperature for a first predetermined time, and the compound shown in formula 3 is obtained after separation;

[0068] Step S2, the compound of formula 3 and the compound shown in formula 4 are obtained under electrochemical conditions to obtain a compound of formula 1;

[0069] Alternatively, the compound shown as formula 2 and nitro tetrafluoroboric acid (NOBF4) are stirred at a first temperature for a first predetermined time to obtain a reaction mixture, without separation, the compound shown as formula 4 is added to the reaction mixture, and the compound shown as formula 1 is obtained by stirring under electrochemical conditions for a second predetermined time.

[0070] The preparation method provided by the embodiment of the application has the advantages of simple operation, mild conditions, good functional group tolerance, etc., and the compound shown as formula 1 can be obtained by two-step reaction and two-step separation or one-step in-situ reaction and separation.

[0071] In some embodiments, the first temperature is room temperature, and the first predetermined time is 1-2 h; the electrochemical conditions are as follows: the working current is 4-15 mA, the electrolyte is tetrabutylammonium hexafluorophosphate or tetrabutylammonium tetrafluoroborate, and the solvent is acetonitrile, tetrahydrofuran or hexafluoroisopropanol; and the molar ratio of the compound shown as formula 2 to nitro tetrafluoroboric acid is (1-1.2):1.

[0072] Under the above operation parameters, the reaction yield can be more than 80%, and the reaction by-products are less, which is convenient for separation and purification.

[0073] In some embodiments, the electrochemical conditions are as follows: the electrochemical reaction cell is a diaphragmless electrolytic cell, the electrode material of the cathode is graphite, and the electrode material of the anode is graphite.

[0074] The preparation method of the embodiment of the application is based on the diaphragmless electrolytic system constructed by the cheap carbon-based electrode, and exhibits excellent functional group compatibility and reaction efficiency while maintaining mild reaction conditions.

[0075] The embodiment of the application provides a capturing method of carborane cage boron free radicals, and the capturing method comprises the following steps:

[0076] The compound shown as formula 1 is added with a radical capturing agent 1,1-diphenyl ethylene, and the compound shown as formula 4 is obtained by stirring under the above electrochemical conditions at a second temperature for a second predetermined time.

[0077] The reaction route of the above reaction is as follows:

[0078]

[0079] In some embodiments, the structure of the compound shown as formula 4 is compound 1:

[0080]

[0081] The benzothiazole skeleton has important application value in the fields of medicine, pesticide and functional material due to its excellent tunability, significant biological activity and unique photoelectric performance (Chem. Soc. Rev. 2013, 42, 5257-5269). In recent years, its green synthesis method (such as electrochemistry, photocatalysis) and high-performance application (such as molecular probe, photoelectric material) have become a research hotspot. However, the synthesis of carborane-benzothiazole hybrid molecules is still a blank field.

[0082] The embodiment of the present application provides a carborane benzothiazole derivative, and a structural general formula of the carborane benzothiazole derivative is as shown in formula 5:

[0083]

[0084] Among them, is C, is B;

[0085] o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B is selected from any B vertex;

[0086] R 1 and R 2 are each selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, or substituted or unsubstituted aryl of 6-20 carbons;

[0087] When o is selected from CR 2 , R 1 and R 2 may be optionally connected to form a ring;

[0088] R 3 , R 4 , R 5 , R 6 are each selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, or substituted or unsubstituted aryl of 6-20 carbons;

[0089] X is selected from S, Se.

[0090] The carborane benzothiazole derivative provided by the embodiment of the present application has strong structural tunability, significant biological activity and excellent photoelectric performance, and has potential application in the development of medicine, pesticide and functional material.

[0091] In some embodiments, the carboranobenzothiazole derivative is any one of compounds 2-25:

[0092]

[0093] The present application provides a preparation method of a carboranobenzothiazole derivative, comprising the following steps:

[0094] stirring the compound shown in formula 2 with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound shown in formula 3;

[0095] stirring the compound shown in formula 3 and the compound shown in formula 6 under electrochemical conditions at the first temperature for a second predetermined time to obtain the compound of formula 5, i.e. the carboranobenzothiazole derivative;

[0096] The synthesis route of the above reaction is as follows:

[0097]

[0098] In some embodiments, the preparation method comprises the following steps:

[0099] Step S5, stirring the compound shown in formula 2 and nitro tetrafluoroboric acid (NOBF4) at a first temperature for a first predetermined time to obtain the compound shown in formula 3 through separation;

[0100] Step S6, stirring the compound of formula 3 and the compound shown in formula 5 under electrochemical conditions at the first temperature for a second predetermined time to obtain the compound of formula 5;

[0101] Alternatively, step S7, stirring the compound shown in formula 2 and nitro tetrafluoroboric acid (NOBF4) at a first temperature for a first predetermined time to obtain a reaction mixture, without separation, directly adding the compound shown in formula 6 to the reaction mixture, and stirring under electrochemical conditions for a second predetermined time to obtain the compound of formula 5.

[0102] The preparation method provided by the present application has the advantages of simple operation, mild conditions, good functional group tolerance, etc. The compound of formula 5 can be obtained through two-step reaction and two-step separation or one-step in-situ reaction and separation. In particular, the method uses clean electric energy to replace traditional chemical reducing agents, which not only simplifies the operation process, but also greatly reduces the production cost, successfully realizes the preparation of carboranobenzothiazole derivatives on a gram scale, and provides a reliable technical scheme for industrial production.

[0103] Furthermore, this invention innovatively develops a novel, metal-free electrochemically induced boron radical strategy for carboranes. This method, through the selective electrochemical reduction of the BN bond under mild conditions, leads to efficient radical cascade cyclization with 2-isocyanoaryl sulfides, offering multiple advantages: it utilizes a membrane-free electrolysis system with inexpensive carbon-based electrodes, making operation simple and easily scaled up; it achieves a one-pot synthesis using air-stable aminocarboranes as raw materials; the product can be subject to diverse post-modification via cage-like carbon vertices; and it uses electric current as a clean reducing agent, avoiding the use of traditional redox reagents. This method has been successfully achieved on a gram-scale basis, providing an efficient and green new route for the synthesis of carborane-benzothiazole hybrid molecules.

[0104] In some embodiments, the molar ratio of the compound shown in Formula 2 to nitric tetrafluoroborate is (1-1.1):1; the molar ratio of the compound shown in Formula 2 to the compound shown in Formula 6 is (1-2):1.

[0105] The present invention will be further described below through specific embodiments.

[0106] The electrochemical device for the electrochemical reaction in this invention is as follows: Figure 1 As shown, the electrochemical reaction occurred in a 10 mL glass bottle ( Figure 1 The experiment was conducted in Figure b, using 1 cm × 1 cm graphite felt as the electrode material. Figure 1 (See Figure a) Secure the graphite felt to the platinum electrode clamp. Connect a power source to the outside of the electrode clamp and apply a constant current (4.0 mA).

[0107] Example 1: Synthesis of Compound 1, a product of carborane-caged boron radical capture.

[0108] In a dry 10 mL round-bottom flask (with a stir bar), add 2-29 3-diazonium salt-o-carborane tetrafluoroborate (25.8 mg, 0.10 mmol), 1,1-stilbene (18.0 mg, 0.1 mmol), and tetrabutylammonium hexafluorophosphate in sequence. n Bu4NPF6 (116.1 mg, 0.3 mmol) and anhydrous acetonitrile (6 mL) were used. A graphite felt (1.0 × 1.0 × 0.3 cm) was placed in the reaction system as electrodes (anode and cathode). The reaction mixture was electrolyzed at a constant current (4 mA) at room temperature with continuous stirring for 1 hour. After the reaction was complete, the mixture was extracted with ethyl acetate and water. The combined organic phases were dried over anhydrous sodium sulfate and filtered. The solvent was removed by vacuum distillation, and the residue was purified by rapid silica gel column chromatography [eluent: petroleum ether / ethyl acetate = 20:1] to give compound 1 (16.5 mg, yield 51%).

[0109] Compound 1, prepared by the above method, is a colorless crystal. Figure 2is the X-ray single crystal diffraction structure of compound 1. The nuclear magnetic characterization of compound 1: 1 H NMR (500 MHz, CDC13): δ 7.42-7.41 (m, 3H), 7.30 (s, 5H), 7.23-7.21 (s, 2H) (Aryl CH), 6.44 (s, 1H) (C=CH), 2.94 (s, 2H). 13 C NMR (125 MHz, CDC13): δ 154.8, 141.4, 140.4, 137.7, 132.6, 130.2, 129.3, 128.9, 128.5, 128.3, 126.9 (Aryl C), 56.2 (Cage-C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -3.02 (2B), -7.13 (IB) (B-C), -8.65 (IB), -12.60 (3B), -13.91 (3B). High resolution mass spectrometry data (APCI mode): [M-H] － Calculated 321.2660, found 321.2648.

[0110] Preparation of compounds 2-1 to 2-20 of Example 2

[0111] The structural formulas of compounds 2-1 to 2-31 are:

[0112]

[0113]

[0114] (1) Compounds 2-1 to 2-28 were prepared according to the method in the prior art literature (for example, Org. Lett. 2018, 20, 3144-3147), and compounds 2-29, 2-30 were prepared according to the method in the prior art literature (for example, J Organomet Chem. 1984, 267, 81-91).

[0115] (2) Compounds 2-1 to 2-28 were prepared by the above method, and the specific preparation method of compound 2-31 is as follows:

[0116]

[0117] Step one, 5,6-dimethylbenzo[d]thiazol-2-amine (0.890 g, 5.0 mmol) and potassium hydroxide (10.0 g, 0.18 mol) were dissolved in 35.0 mL of water, heated to reflux at 120 °C for 24 h. After the reaction solution was cooled to room temperature, iodomethane (0.7 g, 5.0 mmol) was added dropwise. The resulting solution was extracted with diethyl ether (20 mL x 3), and the combined organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The residue was separated by silica gel column chromatography (eluent: n-hexane / ethyl acetate = 10 / 1), and 0.651 g of a brown liquid was finally obtained in 78% yield.

[0118]

[0119] Step two, acetic formic anhydride (0.63 mL) was added dropwise to a stirred solution of 4,5-dimethyl-2-(methylthio)aniline (417 mg, 2.5 mmol) in dichloromethane (5 mL) at 0 °C. After stirring the reaction mixture at room temperature for 2 h, the reaction was quenched with saturated aqueous sodium carbonate solution and extracted with dichloromethane three times. The combined organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure to give a light yellow oil. This intermediate was used directly in the subsequent dehydration reaction without purification.

[0120]

[0121] Step three, under nitrogen protection, to a solution of N-(4,5-dimethyl-2- (methylthio)phenyl)formamide (487 mg, 2.5 mmol) and triethylamine (757 mg, 7.5 mmol) in anhydrous tetrahydrofuran (20 mL) at 0 °C, a solution of phosphorus oxychloride (459 mg, 3 mmol) in tetrahydrofuran (7 mL) was added dropwise slowly within 15 min. The reaction mixture was stirred at 0 °C for 1 h. After the reaction was completed, the system was slowly poured into a saturated potassium carbonate solution (15 mL) at 0 °C, and extracted with diethyl ether three times (20 mL each time). The combined organic phase was dried over anhydrous sodium sulfate, filtered, and concentrated by rotary evaporation. The residue was purified by silica gel column chromatography (eluent: petroleum ether / ethyl acetate = 20 / 1) to give 322 mg of compound as a white solid in 75% yield.

[0122] Compounds 2-1 to 2-30 are known compounds, and the structural characterization data are the same as those reported in the literature (Org. Lett. 2018, 20, 3144-3147). Compound 2-31 is a new compound. Compound 2-31 was prepared by the above method as a white solid (332.4 mg, yield 75%). The nuclear magnetic resonance characterization of compound 2-31: 1H NMR (500 MHz, CDC13): δ 7.11 (s, 1H) (Aryl CH), 7.01 (s, 1H) (Aryl CH), 2.49 (s, 3H) (SCH3), 2.27 (s, 3H) (CH3), 2.20 (s, 3H) (CH3). 13 C NMR (125 MHz, CDC13): δ 167.0, 139.0, 134.7, 132.6, 128.0, 127.9 (Aryl C), 19.9, 19.1 (Aryl-CH3), 15.6 (SCH3). High resolution mass spectral data (APCI mode): [M+H] + Calculated 178.0685, Found 178.0684.

[0123] Synthesis of compound 3-(1,3-benzothiazol-2-yl)-ortho-carborane (2) in Example 3

[0124]

[0125] In a dry round bottom flask (10 mL) equipped with a stir bar, 3-diazo-ortho-carborane tetrafluoroborate (compound 2-29) (25.8 mg, 0.10 mmol), 2-isocyanoaryl sulfide (compound 2-1-2-5) (0.1 mmol), tetrabutylammonium hexafluorophosphate (116.1 mg, 0.3 mmol) and anhydrous acetonitrile (6 mL) were added. The electrochemical cell was equipped with graphite felt (1.0 x 1.0 x 0.3 cm) as anode and cathode, and the electrolysis was carried out at room temperature with constant current 4 mA for 1 hour. After the reaction was completed, the mixture was extracted with ethyl acetate and water, and the organic phase was combined, dried over anhydrous sodium sulfate, filtered and concentrated by rotary evaporation. The product 2 was obtained by silica gel flash column chromatography (petroleum ether / ethyl acetate = 20:1 elution). The yield of 2-1-2-5 as starting material was 86%, 83%, 68%, 79% and 56%, respectively.

[0126] The compound 2 prepared by the above method was colorless crystal. Figure 3 is the X-ray single crystal diffraction structure of compound 2. The nuclear magnetic resonance characterization of compound 2: 1 H NMR (500 MHz, CDC13): δ 7.11 (s, 1H) (Aryl CH), 7.01 (s, 1H) (Aryl CH), 2.49 (s, 3H) (SCH3), 2.27 (s, 3H) (CH3), 2.20 (s, 3H) (CH3). 13C NMR (125 MHz, CDC13): δ 154.5, 137.0, 126.7, 126.0, 123.3, 121.9 (Aryl C), 57.7 (Cage-CH), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.18 (2B), -9.30 (2B), -10.61 (IB), -12.34 (4B) (Cage B-C), -14.15 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 278.2007, Found 278.2001.

[0127] Example 4 Synthesis of carborane benzothiazole derivatives 3-23 using compound 2-29 as starting material

[0128]

[0129] In a dry round bottom flask (10 mL) equipped with a stir bar, 3-diazo-o-carboranetetrafluoroborate (compound 2-29) (25.8 mg, 0.10 mmol), 2-isocyanoaryl sulfide (compound 2-1) (0.1 mmol) or 1-isocyano-2-methoxybenzene (compound 2-26) (13.3 mg, 0.1 mmol) or 2-isocyano-N-methyl-N-phenyl aniline (compound 2-27) (20.8 mg, 0.1 mmol) or (2-isocyano phenyl)(methyl)selenide (compound 2-28) (19.6 mg, 0.1 mmol), tetrabutylammonium hexafluorophosphate (116.1 mg, 0.3 mmol) and anhydrous acetonitrile (6 mL) were added. The apparatus was equipped with a graphite felt (1.0 x 1.0 x 0.3 cm) as anode and cathode, and the electrolysis was carried out at room temperature with a constant current of 4 mA for 1 hour. After the reaction was completed, the mixture was extracted with ethyl acetate and water, and the combined organic phase was dried over anhydrous sodium sulfate, filtered and concentrated by rotary evaporation. The product B (3) -o-carborane benzothiazole derivatives 3-23 was obtained by silica gel flash column chromatography (petroleum ether / ethyl acetate = 20: 1 eluent).

[0130] Compound 3 was obtained as a white solid (24.8 mg, yield 85%) by the above method. The nuclear magnetic resonance characterization of compound 3: 1H NMR (500 MHz, CDC13): δ 7.90 (d, J = 8.5 Hz, IH) (Aryl CH), 7.74 (s, IH) (Aryl CH), 7.32 (d, J = 8.05 Hz, IH) (Aryl CH), 4.16 (s, 2H) (Cage CH), 2.51 (s, 3H) (CH3). 13 C NMR (125 MHz, CDC13): δ 152.9, 137.3, 136.2, 128.4, 122.8, 121.6 (Aryl C), 57.7 (Cage-CH), 21.7 (CH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.16 (2B), -9.22 (2B), -10.73 (IB), -12.28 (4B) (Cage B-C), -14.13 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 292.2163, Found 292.2156.

[0131] Compound 4 prepared by the above method was a white solid (27.0 mg, yield 88%). NMR characterization of compound 4: 1 H NMR (500 MHz, CDC13): δ 7.93 (d, J = 9.0 Hz, IH) (Aryl CH), 7.38 (s, IH) (Aryl CH), 7.13 (dd, J = 9.0, 2.0 Hz, IH) (Aryl CH), 4.24 (s, 2H) (Cage CH), 3.90 (s, 3H) (OCH3). 13 C NMR (125 MHz, CDC13): δ 158.7, 148.2, 138.2, 123.4, 117.1, 103.8 (Aryl C), 57.8 (Cage-CH), 56.0 (OCH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.23 (2B), -9.34 (2B), -10.45 (IB), -12.38 (4B) (Cage B-C), -14.04 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 308.2112, Found 308.2104.

[0132] Compound 5 prepared by the above method was a white solid (28.6 mg, 89% yield). NMR characterization of compound 5: 1 H NMR (500 MHz, CDC13): δ 7.90 (d, J = 8.5 Hz, IH) (Aryl CH), 7.37 (s, IH) (Aryl CH), 7.11 (d, J = 9.0 Hz, IH) (Aryl CH), 4.18 (s, 2H) (Cage CH), 4.11 (q, J = 6.5 Hz, 2H) (OCH2), 1.47 (t, J = 6.5 Hz, 3H) (CH3). 13 C NMR (125 MHz, CDC13): δ 158.2, 147.0, 137.9, 123.1, 117.8, 104.4 (Aryl C), 64.4 (Cage-CH), 57.9 (OCH2), 14.9 (CH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.28 (2B), -9.36 (2B), -10.78 (IB), -12.39 (4B) (Cage B-C), -14.11 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 322.2269, found 322.2260.

[0133] Compound 6 prepared by the above method was a white solid (27.4 mg, 76% yield). NMR characterization of compound 6: 1 H NMR (500 MHz, CDC13): δ 8.05 (d, J = 11.0 Hz, IH) (Aryl CH), 7.83 (d, J = 1.5 Hz, IH) (Aryl CH), 7.40 (dd, J = 9.5, 2.0 Hz, IH) (Aryl CH), 4.19 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 152.5, 147.3, 137.8, 124.1, 120.9, 114.4 (Aryl C), 128.6 (OCH3) 57.7 (Cage-CH), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -1.94 (2B), -9.19 (2B), -10.13 (IB), -12.32 (4B) (Cage B-C), -13.77 (IB).19 F NMR (470 MHz, CDC13): δ -68.0 (s, 3F). High resolution mass spectral data (APCI mode): [M+H] + Calculated 362.1830, Found 362.1819.

[0134] Compound 7 prepared by the above method was a white solid (20.7 mg, yield 70%). NMR characterization of compound 7: 1 H NMR (500 MHz, CD2CI2): δ 7.94 (dd, J = 4.0, 5.0 Hz, 1H) (Aryl CH), 7.71 (dd, J = 7.0, 2.5 Hz, 1H) (Aryl CH), 7.25 (m, 1H) (Aryl CH), 4.24 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CD2CI2): δ 162.4 (d, 1 J C－F = 241.9 Hz), 161.2, 132.9, 123.0 (d, 3 J C－F = 9.9 Hz), 115.0 (d, 2 J C－F = 25.4 Hz), 109.4 (d, 2 J C－F = 23.0 Hz) (Aryl C), 58.3 (Cage C), 37.3 (C cage -CH2), the Bcage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CD2CI2): δ -2.66 (2B), -9.70 (2B), -10.97 (IB), -12.67 (4B) (Cage B-C), -14.26 (IB). 19 F NMR (470 MHz, CDC13): δ -68.0 (s, 3F). High resolution mass spectral data (APCI mode): [M+H] + Calculated 362.1830, Found 362.1819.

[0135] Compound 8 prepared by the above method was a white solid (23.6 mg, yield 76%). NMR characterization of compound 8: 1H NMR (500 MHz, CDC13): δ 7.96 (m, IH) (Aryl CH), 7.50 (m, IH) (Aryl CH), 7.28 (m, IH) (Aryl CH), 4.20 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 153.3, 138.3, 132.3, 127.6, 124.0, 121.5 (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.08 (2B), -9.34 (2B), -10.47 (IB), -12.53 (4B) (Cage B-C), -14.09 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 312.1620, Found 312.1608.

[0136] Compound 9 prepared by the above method was a white solid (23.6 mg, yield 76%). NMR characterization of compound 9: 1 H NMR (500 MHz, CDC13): δ 8.10 (s, IH) (Aryl CH), 7.87 (dd, J = 7.5, 1.0 Hz, IH) (Aryl CH), 7.61 (d, J = 8.5 Hz, IH) (Aryl CH), 4.15 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 151.7, 138.7, 128.5, 126.9, 126.4, 120.5 (Aryl C), 57.8 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.01 (2B), -9.24 (2B), -10.40 (IB), -12.32 (4B) (Cage B-C), -14.03 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 358.1078, Found 358.1088.

[0137] Compound 10 prepared by the above method was a white solid (24.2 mg, yield 83%). NMR characterization of compound 10: 1H NMR (500 MHz, CDC13): δ 7.85 (m, 2H) (Aryl CH), 7.30 (d, J = 8.5 Hz, IH) (Aryl CH), 4.25 (s, 2H) (Cage CH), 2.52 (s, 3H) (CH3). 13 C NMR (125 MHz, CDC13): δ 137.3, 133.8, 128.0, 122.9, 121.4 (Aryl C), 57.8 (Cage C), 21.6 (CH3), the Bcage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.11 (2B), -9.20 (2B), -10.41 (IB), -12.31 (4B) (Cage B-C), -14.01 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 292.2163, Found 292.2155.

[0138] Compound 11 prepared by the above method was colorless crystal (26.1 mg, yield 85%). Figure 4 is the X-ray single crystal diffraction structure diagram of compound 10. The nuclear magnetic characterization of compound 11: 1 H NMR (500 MHz, CDC13): δ 7.81 (d, J = 9.0 Hz, IH) (Aryl CH), 7.52 (s, IH) (Aryl CH), 7.12 (d, J = 8.5 Hz, IH) (Aryl CH), 4.24 (s, 2H) (Cage CH), 3.90 (s, 3H) (OCH3). 13 C NMR (125 MHz, CDC13): δ 159.4, 155.8, 128.9, 122.0, 116.6, 104.9 (Aryl C), 57.5 (Cage C), 55.7 (OCH3), the Bcage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.18 (2B), -9.25 (2B), -10.50 (IB), -12.42 (4B) (Cage B-C), -14.16 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 308.2112, Found 308.2104.

[0139] Compound 12 prepared by the above method was a white solid (20.1 mg, 68% yield). NMR characterization of compound 12: 1 H NMR (500 MHz, CDC13): δ 7.90 (dd, J = 4.0, 5.0 Hz, IH) (Aryl CH), 7.72 (dd, J = 7.0, 2.5 Hz, IH) (Aryl CH), 7.25 (m, IH) (Aryl CH), 4.22 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 162.2 (d, 1 J C－F = 243.6 Hz), 154.6, 132.2, 124.7 (d, 3 J C－F = 9.9 Hz), 115.3 (d, 2 J C－F = 25.1 Hz), 109.1 (d, 2 J C－F = 23.5 Hz) (Aryl C), 57.8 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.02 (2B), -9.27 (2B), -10.39 (IB), -12.29 (4B) (Cage B-C), -14.09 (IB). 19 F NMR (470 MHz, CDC13): δ -115.0 (s, IF). High resolution mass spectral data (APCI mode): [M + H] + Calculated 296.1912, Found 296.1904.

[0140] Compound 13 prepared by the above method was a white solid (22.1 mg, 71% yield). NMR characterization of compound 13: 1 H NMR (500 MHz, CDC13): δ 8.04 (d, J = 9.0 Hz, IH) (Aryl CH), 7.83 (s, IH) (Aryl CH), 7.40 (d, J = 9.0 Hz, IH) (Aryl CH), 4.19 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 152.7, 147.3, 137.8, 124.1, 120.8, 114.4 (Aryl C), 57.7 (Cage C), the B cage-C was not observed.11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.05 (2B), -9.33 (2B), -10.35 (IB), -12.45 (4B) (Cage B-C), -14.87 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 312.1620, Found 312.1608.

[0141] Compound 14 prepared by the above method was a white solid (27.5 mg, yield 77%). NMR characterization of compound 14: 1 H NMR (500 MHz, CDC13): δ 8.18 (s, IH) (Aryl CH), 7.83 (d, J = 8.5 Hz, IH) (Aryl CH), 7.56 (dd, J = 6.5, 2.0 Hz, IH) (Aryl CH), 4.17 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 155.5, 135.7, 129.3, 126.2, 123.0, 120.5 (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.08 (2B), -9.34 (2B), -10.42 (IB), -12.43 (4B) (Cage B-C), -14.18 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 358.1078, Found 358.1086.

[0142] Compound 15 prepared by the above method was a white solid (23.0 mg, yield 79%). NMR characterization of compound 15: 1 H NMR (500 MHz, CDC13): δ 7.79 (d, J = 7.5 Hz, IH) (Aryl CH), 7.35 (m, 2H) (Aryl CH), 4.34 (s, 2H) (Cage CH), 2.77 (s, 3H) (CH3). 13 C NMR (125 MHz, CDC13): δ 153.0, 136.6, 133.4, 127.4, 126.2, 119.3 (Aryl C), 58.0 (Cage C), 18.7 (CH3), the B cage-C was not observed. 11 B{1 H}NMR (160 MHz, CDC13): δ -2.27 (2B), -9.36 (2B), -10.52 (IB), -12.33 (4B) (Cage B-C), -14.07 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 292.2163, Found 292.2155.

[0143] Compound 16 prepared by the above method was a white solid (20.6 mg, yield 67%). NMR characterization of compound 16: 1 H NMR (500 MHz, CDC13): δ 7.54 (d, J = 8.5 Hz, IH) (Aryl CH), 7.41 (t, J = 8.0 Hz, IH) (Aryl CH), 6.94 (d, J = 8.0 Hz, IH) (Aryl CH), 4.31 (s, 2H) (Cage CH), 4.06 (s, 3H) (OCH3). 13 CNMR (125 MHz, CDC13): δ 153.6, 144.6, 138.8, 127.2, 113.9, 106.9 (Aryl C), 57.7 (Cage C), 56.3 (OCH3), the B cage-C was not observed. 11 B{ 1 H}NMR (160 MHz, CDC13): δ -2.25 (2B), -9.25 (2B), -10.61 (IB), -12.31 (4B) (Cage B-C), -14.18 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 308.2112, Found 308.2104.

[0144] Compound 17 prepared by the above method was a white solid (21.3 mg, yield 72%). NMR characterization of compound 17: 1 H NMR (500 MHz, CDC13): δ 7.73 (d, J = 8.5 Hz, IH) (Aryl CH), 7.41 (m, IH) (Aryl CH), 7.21 (t, J = 8.0 Hz, IH) (Aryl CH), 4.23 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 156.2 (d, 1 J C－F = 255.1 Hz), 145.3, 139.9, 126.8 (d, 3 JC－F = 7.0 Hz), 117.7 (d, 3 J C－F = 4.3 Hz), 112.1 (d, 2 J C－F = 17.9 Hz) (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.06 (2B), -9.27 (2B), -10.39 (IB), -12.26 (4B) (Cage B-C), -14.05 (IB). 19 F NMR (470 MHz, CDC13): δ -121.7 (s, IF). High resolution mass spectral data (APCI mode): [M+H] + Calculated 296.1912, Found 296.1904.

[0145] Compound 18 prepared by the above method was a white solid (22.4 mg, yield 72%). NMR characterization of compound 18: 1 H NMR (500 MHz, CDC13): δ 7.86 (d, J = 8.0 Hz, IH) (Aryl CH), 7.53 (d, J = 8.0 Hz, IH) (Aryl CH), 7.37 (m, IH) (Aryl CH), 4.25 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 151.7, 138.7, 128.5, 126.8, 126.4, 120.5 (Aryl C), 57.8 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.11 (2B), -9.35 (2B), -10.45 (IB), -12.25 (4B) (Cage B-C), -14.10 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 312.1620, Found 312.1608.

[0146] Compound 19 prepared by the above method was a white solid (26.1 mg, yield 73%). NMR characterization of compound 19: 1H NMR (500 MHz, CDC13): δ 7.90 (dd, J = 5.0, 4.0 Hz, IH) (Aryl CH), 7.70 (dd, J = 7.0, 2.5 Hz, IH) (Aryl CH), 7.22 (m, IH) (Aryl CH), 4.18 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 150.5, 139.3, 132.1, 128.9, 127.4, 120.1 (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.36 (2B), -9.68 (2B), -10.56 (IB), -12.68 (4B) (Cage B-C), -14.37 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 358.1078, Found 358.1086.

[0147] Compound 20 prepared by the above method was a white solid (18.8 mg, yield 60%). NMR characterization of compound 20: 1 H NMR (500 MHz, CDC13): δ 7.45 (d, J = 7.5 Hz, IH) (Aryl CH), 7.03 (t, J = 9.5 Hz, IH) (Aryl CH), 4.20 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 161.8, 159.9, 156.6, 154.5, 140.7, 140.1, 140.0, 104.0, 103.8, 102.8, 102.5 (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.08 (2B), -9.44 (2B), -10.39 (IB), -12.74 (4B) (Cage B-C), -14.17 (IB). 19 F NMR (470 MHz, CDC13): δ -111.2 (s, IF), -117.1 (s, IF) (Aryl C-F). High resolution mass spectral data (APCI mode): [M+H] + Calculated 314.1818, Found 314.1809.

[0148] Compound 21 prepared by the above method was a white solid (26.0 mg, 75% yield). NMR characterization of compound 21: 1 H NMR (500 MHz, CDC13): δ 7.84 (s, IH) (Aryl CH), 7.53 (s, IH) (Aryl CH), 4.22 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 150.5, 139.3, 132.1, 128.9, 127.4, 120.1 (Aryl C), 57.7 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.70 (2B), -10.04 (2B), -10.92 (IB), -13.03 (4B) (Cage B-C), -14.64 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 347.1206, found 347.1182.

[0149] Compound 22 prepared by the above method was a white solid (25.0 mg, 82% yield). NMR characterization of compound 22: 1 H NMR (500 MHz, CDC13): δ 7.79 (s, IH) (Aryl CH), 7.70 (s, IH) (Aryl CH), 4.16 (s, 2H) (Cage CH), 2.40 (s, 6H) (CH3). 13 C NMR (125 MHz, CDC13): δ 153.5, 136.1, 135.7, 134.5, 123.2, 121.7 (Aryl C), 57.6 (Cage C) 20.4, 20.3 (CH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.19 (2B), -9.24 (2B), -10.72 (IB), -12.29 (4B) (Cage B-C), -14.04 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 306.2320, found 306.2310.

[0150] Compound 23 prepared by the above method was a white solid (26.7 mg, 82% yield). NMR characterization of compound 23:1 H NMR (500 MHz, CDC13): δ 8.10 (d, J = 8.5 Hz, IH) (Aryl CH), 8.01 (d, J = 8.0 Hz, IH) (Aryl CH), 7.52 (t, J = 8.0 Hz, IH) (Aryl CH), 7.39 (t, J = 8.0 Hz, IH) (Aryl CH), 4.21 (s, 2H) (Cage CH). 13 C NMR (125 MHz, CDC13): δ 155.6, 140.1, 126.8, 126.2, 125.2, 124.8 (Aryl C), 57.5 (Cage C), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -2.26 (2B), -8.52 (IB), -9.09 (IB), -10.82 (IB), -12.35 (4B) (Cage B-C), -14.11 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 326.1444, Found 326.1445.

[0151] Example 4 Preparation of compounds 2-10, 13, 15, 17, 20-22 by in situ one-step reaction

[0152]

[0153] A solution of 3-amino-o-carborane (compound 2-30) (15.9 mg, 0.1 mmol) in dry acetonitrile (1.0 mL) was placed in an environment of -20 °C, and nitrosonium tetrafluoroborate (NOBF4, 13.1 mg, 0.11 mmol) was added. The reaction mixture was stirred at 0 °C for 1 hour. Subsequently, the solution was transferred to an oven-dried single-necked round-bottom flask (10 mL) equipped with a stir bar, and 0.1 mmol of 2-isocyano aryl sulfide (compounds 2-10, 13, 15, 17, 20-22), tetrabutylammonium hexafluorophosphate (Bu4NPF6, 116.1 mg, 0.3 mmol), and dry acetonitrile (5 mL) were added. Graphite felt (1.0 x 1.0 x 0.3 cm) was used as the cathode and anode, and the electrolysis was carried out at room temperature with a constant current of 4 mA for 1 hour. After the reaction was completed, the mixture was extracted with ethyl acetate and water, and the combined organic phase was dried over anhydrous sodium sulfate and filtered. The solvent was concentrated on a rotary evaporator. Finally, the pure product B (3)-o-carborane benzothiazole derivative was purified by silica gel flash column chromatography using petroleum ether / ethyl acetate (20:1) as the eluent. n Bu4NPF6, 116.1 mg, 0.3 mmol) and dry acetonitrile (5 mL). Graphite felt (1.0 x 1.0 x 0.3 cm) was used as the cathode and anode, and the electrolysis was carried out at room temperature with a constant current of 4 mA for 1 hour. After the reaction was completed, the mixture was extracted with ethyl acetate and water, and the combined organic phase was dried over anhydrous sodium sulfate and filtered. The solvent was concentrated on a rotary evaporator. Finally, the pure product B (3)-o-carborane benzothiazole derivative was purified by silica gel flash column chromatography using petroleum ether / ethyl acetate (20:1) as the eluent.

[0154] Compound 2 was obtained as colorless crystals (19.7 mg, 71% yield) by the above method. Compound 3 was obtained as white solid (21.3 mg, 73% yield). Compound 4 was obtained as white solid (23.0 mg, 75% yield). Compound 5 was obtained as white solid (23.8 mg, 74% yield). Compound 6 was obtained as white solid (25.6 mg, 71% yield). Compound 7 was obtained as white solid (17.7 mg, 60% yield). Compound 8 was obtained as white solid (22.1 mg, 71% yield). Compound 9 was obtained as white solid (25.7 mg, 72% yield). Compound 10 was obtained as white solid (20.1 mg, 69% yield). Compound 13 was obtained as white solid (21.1 mg, 71% yield). Compound 15 was obtained as white solid (19.8 mg, 68% yield). Compound 17 was obtained as white solid (15.6 mg, 53% yield). Compound 20 was obtained as white solid (18.8 mg, 60% yield). Compound 21 was obtained as white solid (17.6 mg, 51% yield). Compound 22 was obtained as white solid (22.6 mg, 74% yield). The compounds obtained were characterized by NMR and were the same as the corresponding compounds obtained in Example 3.

[0155] Preparation of compounds 24, 25 of Example 5

[0156] To a solution of 2 (0.1 mmol, 27.7 mg) in dry tetrahydrofuran (2 mL), potassium bis(trimethylsilyl)amide solution (KHMDS, 1.0 M in tetrahydrofuran; 2.2 eq, 0.22 mmol, 0.22 mL) was added at room temperature. The resulting solution was stirred at room temperature for 2 hours. Then iodomethane or iodoethane (2.0 eq, 0.2 mmol) was added dropwise at 0 °C and the stirring was continued at room temperature for 6 hours. After the reaction was completed, the reaction was quenched by the addition of water (10 mL). The mixture was extracted with ethyl acetate and water, and the combined organic phase was dried over anhydrous sodium sulfate, filtered, and the solvent was concentrated on a rotary evaporator. Finally, the product compounds 24 (27.8 mg, 91%) and 25 (30.0 mg, 90%) were purified by flash column chromatography on silica gel using petroleum ether / ethyl acetate (20:1) as eluent.

[0157] Compound 24 was obtained as white solid (27.8 mg, 71% yield) by the above method. NMR characterization of compound 24: 1 H NMR (500 MHz, CDC13): δ 8.12 (d, J = 8.5 Hz, 1H) (Aryl CH), 7.98 (d, J = 8.0 Hz, 1H) (Aryl CH), 7.51 (m, 1H) (Aryl CH), 7.45 (m, 1H) (Aryl CH), 2.20 (s, 6H) (CH3). 13C NMR (125 MHz, CDC13): δ 155.4, 136.5, 126.3, 125.8, 123.9, 121.6 (Aryl C), 74.9 (Cage-CCH3), 21.3 (Cage-CCH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -4.97 (2B), -6.43 (IB), -7.90 (IB) (Cage B-C), -8.62 (2B), -9.44 (3B), -10.50 (IB). High resolution mass spectral data (APCI mode): [M+H] + Calculated 306.2320, Found 306.2311.

[0158] Compound 25 prepared by the above method was colorless crystal (30.0 mg, yield 90%), Figure 4 is the X-ray single crystal diffraction structure diagram of compound 25. The nuclear magnetic characterization of compound 25: 1 H NMR (500 MHz, CDC13): δ 8.11 (d, J = 8.5 Hz, IH) (Aryl CH), 7.97 (d, J = 8.0 Hz, IH) (Aryl CH), 7.51 (t, J = 7.5 Hz, IH) (Aryl CH), 7.44 (t, J = 7.0 Hz, IH) (Aryl CH), 2.74 (m, 2H) (CH2), 2.30 (m, 2H) (CH2), 1.17 (t, J = 7.5 Hz, 6H) (CH3). 13 C NMR (125 MHz, CDC13): δ 155.3, 136.5, 126.3, 125.8, 123.9, 121.6 (Aryl C), 81.8 (Cage-C), 26.2 (CH2), 14.0 (CH3), the B cage-C was not observed. 11 B{ 1 H} NMR (160 MHz, CDC13): δ -4.56 (2B), -7.58 (IB), -8.34 (IB) (Cage B-C), -9.56 (3B), -10.69 (IB), -12.20 (2B). High resolution mass spectral data (APCI mode): [M+H] + Calculated 334.2634, Found 334.2623.

[0159] Preparation of compound 3-(1,3-benzothiazol-2-yl)-ortho-carborane on a gram scale

[0160] In a dry glass beaker (100 mL) equipped with a stir bar, add 3-diazo-o-carborane tetrafluoroborate (compound 2-29) (1.032 g, 4.0 mmol), (2-isocyanophenyl)(methyl) sulfide 2-1 (596.8 mg, 4 mmol), and tetrabutylammonium hexafluorophosphate (…). n Bu4NPF6 (1.549 g, 4.0 mmol) and anhydrous acetonitrile (80 mL) were used. Electrolysis was performed at a constant current of 45 mA for 6 hours at room temperature using graphite felt (4.0 × 3.5 × 0.5 cm) as the cathode and anode. After the reaction, the mixture was extracted with ethyl acetate and water. The combined organic phases were dried over anhydrous sodium sulfate and filtered. The solvent was concentrated using a rotary evaporator. Finally, the product was purified by rapid silica gel column chromatography using petroleum ether / ethyl acetate (20:1) as the eluent to give product 2 (0.898 g, 81% yield).

[0161] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A carborane cage boronyl radical characterized by, The structural formula of the carborane cage boron radical is shown as formula 1: wherein is C, is B; o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B is selected from any B vertex; R 1 and R 2 each is selected from one independently selected from H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, substituted or unsubstituted aryl of 6-20 carbons; When o is selected from CR 2 and R 1 and R 2 may optionally be joined to form a ring.

2. A method of preparing a carborane cage boronyl radical according to claim 1, characterized in that, The preparation method comprises the following steps: The compound shown as formula 2 is stirred with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound shown as formula 3; The compound shown as formula 3 is subjected to electrochemical conditions to obtain the compound shown as formula 1, that is, the carborane cage boron radical; The synthesis route of the above reaction is as follows:

3. The method of claim 2, wherein the carbonborane cage boronyl radical is prepared by the reaction of a carbonborane with a boronyl radical. The first temperature is room temperature, the first predetermined time is 1-2h, the electrochemical conditions are that the working current is 4-15mA, the electrolyte is tetrabutylammonium hexafluorophosphate or tetrabutylammonium tetrafluoroborate, and the solvent is acetonitrile, tetrahydrofuran or hexafluoroisopropanol; and the molar ratio of the compound shown as formula 2 to nitro tetrafluoroboric acid is (1-1.2):

1.

4. The method of claim 3, wherein the carbonborane cage boronyl radical is prepared by the reaction of a carbonborane with a boronyl radical. The electrochemical conditions are that the electrochemical reaction cell is a diaphragmless electrolytic cell, the electrode material of the cathode is graphite, and the electrode material of the anode is graphite.

5. A method of trapping a carborane cage boron radical, characterized by, The capturing method comprises the following steps: The compound shown as formula 1 is added with a radical capturing agent 1,1-diphenyl ethylene, and is stirred at a second temperature for a second predetermined time under the electrochemical conditions in claim 2 to obtain a compound shown as formula 4; The reaction route of the above reaction is as follows:

6. The method for capturing carborane caged boron radicals according to claim 5, characterized in that, The second temperature is room temperature, the second predetermined time is 1-2h, and the molar ratio of the compound shown as formula 1 to 1,1-diphenyl ethylene is (1-1.1):

1.

7. A carborane benzothiazole derivative, characterized in that, The structural general formula of the carborane benzothiazole derivative is shown as formula 5: wherein is C, is B; o, m, p are each independently selected from CR 2 or BH; and when o is selected from CR 2 , m, p are selected from BH; when m is selected from CR 2 , o, p are selected from BH; when p is selected from CR 2 , o, m are selected from BH; B in B-NH2 is selected from any one of the B vertices; R 1 and R 2 each is selected from one independently selected from H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, substituted or unsubstituted aryl of 6-20 carbons; when o is selected from CR 2 R 1 and R 2 may optionally be joined to form a ring; R 3 R 4 R 5 R 6 each is selected from one of H, OH, SH, NH2, halogen, trimethylsilyl, substituted or unsubstituted alkyl of 1-15 carbons, substituted or unsubstituted benzyl, or substituted or unsubstituted aryl of 6-20 carbons; X is selected from S and Se.

8. A process for the preparation of the carboranobenzothiazole derivative according to claim 7, characterized in that, The preparation method comprises the following steps: The compound shown as formula 2 is stirred with nitro tetrafluoroboric acid at a first temperature for a first predetermined time to obtain a compound shown as formula 3; The compound shown as formula 3 is stirred with a compound shown as formula 6 at a first temperature for a second predetermined time under electrochemical conditions to obtain the compound shown as formula 5, that is, the carborane benzothiazole derivative; The synthesis route of the above reaction is as follows:

9. The method for preparing the carborane benzothiazole derivative according to claim 7, characterized in that, The molar ratio of the compound shown as formula 2 to nitro tetrafluoroboric acid is (1-1.1):1, and the molar ratio of the compound shown as formula 2 to the compound shown as formula 6 is (1-2):1.

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