A method for synthesizing an ester-substituted o-carborane derivative

Abstract

The application provides a synthesis method of an o-carborane compound, and is suitable for preparation of an ester group substituted o-carborane derivative. The synthesis steps comprise the following steps: taking 1-carboxyl-2-(substituent)-o-carborane and a high-valence iodine reagent as raw materials, a hydration and substitution reaction is generated in a solvent at a reaction temperature of 50 DEG C to 120 DEG C and a reaction time of 2h to 36h to generate 1-ester group-2-(substituent)-o-carborane compound. The reactants involved in the application have good universality, and the functional groups of the substrates have good compatibility; the synthesis method provided by the application has high selectivity and yield, the reaction system is simple in composition, the post-treatment is simple, and the method is easy to implement.

Description

Technical Field

[0001] This invention relates to a method for synthesizing carboranes, and more particularly to a method for synthesizing ester-substituted ortho-carborane derivatives. Background Technology

[0002] Carboranes have a polyhedral closed cage structure and are characterized by high calorific value, high boron content, and good thermal and chemical stability. They are a class of high-performance burning rate catalysts. In addition, carboranes are used as metal ligands and neutron absorbers in coordination chemistry and medicine. These compounds are liquids at room temperature, and in solid propellants, in addition to their main role in regulating the burning rate, they also function as plasticizers.

[0003] Currently, the synthesis of carbon-substituted carboranes requires lithium salts as reactants. This method involves three steps: first, 1,2-carborane reacts with n-butyllithium to generate a lithium carborane salt intermediate; second, the lithium carborane salt reacts with an stoichiometric amount of cuprous chloride to obtain a copper carborane salt intermediate; and third, the copper carborane salt reacts with a bromide to synthesize the substituted carborane. However, this method requires an stoichiometric amount of cuprous chloride, involves multiple reaction steps, has a low yield (only 43%), and is costly. Furthermore, in literature reports using carboranes containing carboxyl groups as reactants, the carboxyl group typically acts as a directing group, activating the BH bond on B(4,5) to achieve functionalization of the boron cage, and cannot serve as an intermediate for further reactions at the carbon site. Summary of the Invention

[0004] To address the shortcomings and defects of existing technologies, this invention provides a method for synthesizing ester-substituted ortho-carborane derivatives, which has the advantages of high yield and good reactant versatility.

[0005] The present invention includes:

[0006] A method for synthesizing an ester-substituted o-carborane derivative, wherein the method uses 1-carboxy-2-(substituent)-o-carborane and a high-valent iodine reagent as raw materials, and the reaction equation is as follows:

[0007]

[0008] Where R 1 It can be a straight-chain alkyl, branched-chain alkyl, aryl, benzyl, substituted aryl, or H;

[0009] R 2 It can be a straight-chain alkyl, branched alkyl, aryl, or substituted aryl.

[0010] Optionally, the molar ratio of 1-carboxy-2-(substituent)-o-carborane to high-valent iodine reagent is 1:(1-5), the reaction temperature is 50-120℃, and the reaction time is 2-36h.

[0011] Optionally, the reaction temperature is 50–120℃ and the reaction time is 2–36 h.

[0012] Optionally, the solvent is selected from toluene, xylene, mesitylene, and dichloromethane;

[0013] The amount of solvent added is: 1 ml of solvent for every 0.1 mmol of 1-carboxy-2-(substituent)-o-carborane.

[0014] Optionally, the 1-carboxy-2-(substituted)-o-carborane is selected from one of 1-carboxy-1,2-o-carborane, 1-carboxy-2-methyl-o-carborane, 1-carboxy-2-n-butyl-o-carborane, 1-carboxy-2-n-hexyl-o-carborane, and 1-carboxy-2-substituted phenyl-o-carborane.

[0015] Optionally, R in the high-valent iodine reagent 2 The group is selected from methyl, ethyl, n-butyl, n-hexyl, cyclohexyl, aryl, and substituted aryl groups, wherein the aryl group contains one or more substituents on the benzene ring, and the substituents on the benzene ring are methyl, methoxy, halogen, or trifluoromethyl.

[0016] Optionally, an additive, namely acetic acid, may also be added.

[0017] Optionally, the molar ratio of the additive to 1-carboxy-2-(substituent)-o-carborane is 1:1.

[0018] Optional, 1-carboxy-2-n-hexyl-o-carborane, high-valent iodine reagent, R 2 The molar ratio of phenyl, 1-carboxy-2-(substituent)-o-carborane to high-valent iodine reagent was 1:1.2. Toluene and acetic acid were added, and the mixture was stirred at 80°C for 5 hours. After the reaction was completed, the solvent was evaporated, and the mixture was purified by column chromatography to obtain 1-formyloxyacetophenone-2-n-hexyl-o-carborane.

[0019] Optionally, the amount of toluene added is: 1 ml of toluene for every 0.1 mmol of 1-carboxy-2-(substituent)-o-carborane; the molar ratio of acetic acid to 1-carboxy-2-(substituent)-o-carborane is 1:1.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1. The present invention has a short reaction time and is convenient and simple.

[0022] 2. The reactants involved in the method of this invention have good universality.

[0023] 3. The reaction involved in the method of the present invention has a high yield, a simple reaction system composition, and relatively simple post-processing. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 NMR of 1-formyloxyacetophenone-2-n-hexyl-o-carborane obtained in Example 1 1 1H NMR spectrum (500MHz, CDCl3);

[0026] Figure 2 NMR of 1-formyloxyacetophenone-2-n-hexyl-o-carborane obtained in Example 1 13 C{ 1 126MHz, CDCl3 NMR spectrum;

[0027] Figure 3 NMR of 1-formyloxyacetophenone-2-n-hexyl-o-carborane obtained in Example 1 11 B NMR spectrum (160MHz, CDCl3);

[0028] Figure 4 NMR of 1-formyloxyacetophenone-2-n-hexyl-o-carborane obtained in Example 1 11 B{ 1 H NMR spectrum (160MHz, CDCl3); Detailed Implementation

[0029] The present invention will be further described below with reference to specific embodiments.

[0030] The present invention provides a method for synthesizing ester-substituted o-carborane derivatives, using 1-carboxy-2-(substituent)-o-carborane and high-valent iodine reagent as raw materials. The reaction equation is as follows:

[0031]

[0032] Where R 1 It can be a straight-chain alkyl, branched-chain alkyl, aryl, benzyl, or substituted aryl;

[0033] R 2 It can be a straight-chain alkyl, branched-chain alkyl, aryl, or substituted aryl.

[0034] The method uses 1-carboxy-2-(substituent)-o-carborane and high-valent iodine reagent as raw materials, and includes the following steps: using 1-carboxy-2-(substituent)-o-carborane and high-valent iodine reagent as raw materials, a hydration and substitution reaction occurs in a solvent to generate 1-ester-2-(substituent)-o-carborane compound.

[0035] The solvent is toluene, xylene, mesitylene, or dichloromethane; the amount of solvent added is: 1 ml of solvent for every 0.1 mmol of 1-carboxy-2-(substituent)-o-carborane;

[0036] An additive, acetic acid, is also added; the molar ratio of the additive to 1-carboxy-2-(substituent)-o-carborane is 1:1.

[0037] The molar ratio of 1-carboxy-2-(substituent)-o-carborane to high-valent iodine reagent is 1:(1-5), the reaction temperature is 50-120℃, and the reaction time is 2-36h.

[0038] The 1-carboxy-2-(substituent)-o-carborane of the present invention is preferably 1-carboxy-1,2-o-carborane, 1-carboxy-2-methyl-o-carborane, 1-carboxy-2-n-butyl-o-carborane, 1-carboxy-2-n-hexyl-o-carborane, or 1-carboxy-2-substituted phenyl-o-carborane; high-valent iodine reagent R 2 The preferred substituents are methyl, ethyl, n-butyl, n-hexyl, cyclohexyl, aryl, and substituted aryl, with one or more substituents on the benzene ring. The preferred substituents on the benzene ring are methyl, methoxy, halogen, and trifluoromethyl.

[0039] Example 1: Synthesis of 1-formyloxyacetophenone-2-n-hexyl-o-carborane

[0040] Place a 5 mL reaction flask with a magnetic inlet, and add 27 mg (0.1 mmol) of 1-carboxy-2-n-hexyl-o-carborane, and high-valent iodine reagent (R... 2 44 mg (0.12 mmol) of phenyl acetone was added to 1 mL of toluene and 6 mg (0.1 mmol) of acetic acid. The mixture was stirred at 80 °C for 5 hours. After the reaction was completed, the solvent was evaporated, and the mixture was purified by silica gel column chromatography (200-300 mesh) (eluents were n-hexane and ethyl acetate, volume ratio of n-hexane to ethyl acetate = 5:1) to obtain 33 mg of 1-formyloxyacetophenone-2-n-hexyl-o-carborane, yield 85%.

[0041] Structural assessment:

[0042] 1¹H NMR (500MHz, deuterated chloroform, δ / ppm) δ 7.88 (dd, J = 8.3, 1.2Hz, 1H), 7.65 (t, J = 7.5Hz, 1H), 7.51 (t, J = 7.8Hz, 1H), 5.47 (s, 1H), 2.56–2.34 (m, 2H), 1.59 (dt, J = 10.4, 8.0Hz, 1H), 1.40–1.21 (m, 3H), 0.88 (dd, J = 9.2, 4.5Hz, 2H). 13 C NMR (26MHz, deuterated chloroform, δ / ppm) δ 189.53, 159.32, 134.38, 133.50, 129.07, 127.72, 82.03, 74.09, 68.80, 36.07, 31.25, 29.63, 28.72, 22.45, 13.96. 11 B NMR (160MHz, deuterated chloroform, δ / ppm) δ -1.49 (1B), -4.89 (1B), -9.68 (2B), -10.66 (6B). FTIR (KBr, cm⁻¹) -1 ):ν3500,3393,3065,2956,2931,2858,2583,1965,1758,1706,1599,1584,1451,1428,1367,1281,1227,1141,960,836,750,687.

[0043] The above structural characterization data confirm that the obtained compound is 1-formyloxyacetophenone-2-n-hexyl-o-carborane.

[0044] Examples 2-19

[0045] Examples 2-19 synthesized 1-formyloxyacetophenone-2-n-hexyl-o-carborane using the same method as in Example 1, by changing the substituent R 1 and R 2 The experimental results are shown in the table below:

[0046]

[0047]

[0048] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A method for synthesizing ester-substituted ortho-carborane derivatives, characterized in that, The synthetic method described above uses 1-carboxy-2-(substituent)-o-carborane and high-valent iodine reagent as raw materials, and the reaction equation is as follows: ； The molar ratio of 1-carboxy-2-(substituent)-o-carborane to high-valent iodine reagent is 1:(1-5), the reaction temperature is 50-120℃, and the reaction time is 2-36h; The 1-carboxy-2-(substituent)-o-carborane is selected from one of 1-carboxy-1,2-o-carborane, 1-carboxy-2-methyl-o-carborane, 1-carboxy-2-n-butyl-o-carborane, and 1-carboxy-2-n-hexyl-o-carborane; R in the high-valent iodine reagent 2 The aryl group is selected from methyl, ethyl, n-butyl, n-hexyl, cyclohexyl, aryl, and substituted aryl, wherein the aryl group is phenyl, the substituted aryl group is substituted phenyl, and the substituent of the substituted aryl group is one or more of methyl, methoxy, halogen, and trifluoromethyl. An additive, namely acetic acid, is also added, and the molar ratio of the additive to 1-carboxy-2-(substituent)-o-carborane is 1:

1.

2. The method for synthesizing ester-substituted ortho-carborane derivatives according to claim 1, characterized in that, The solvent is selected from one of toluene, xylene, mesitylene, and dichloromethane; The amount of solvent added is: 1 ml of solvent for every 0.1 mmol of 1-carboxy-2-(substituent)-o-carborane.

3. The method for synthesizing ester-substituted ortho-carborane derivatives according to claim 1 or 2, characterized in that, 1-Carboxy-2-(Substituent)o-Carborane is 1-carboxy-2-n-hexyl-o-carborane, a high-valent iodine reagent, R 2 The reaction mixture was phenyl, 1-carboxy-2-(substituent)-o-carborane, and a high-valent iodine reagent in a molar ratio of 1:1.

2. Toluene and acetic acid were added, and the mixture was stirred at 80°C for 5 hours. After the reaction was completed, the solvent was evaporated, and the mixture was purified by column chromatography to obtain 1-formyloxyacetophenone-2-hexyl-o-carborane.

4. The method for synthesizing ester-substituted ortho-carborane derivatives according to claim 3, characterized in that, The amount of toluene added is: 1 ml of toluene for every 0.1 mmol of 1-carboxy-2-(substituent)-o-carborane; The molar ratio of acetic acid to 1-carboxy-2-(substituent)-ortho-carboborane is 1:1.

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