A method for the synthesis of gem-diboron compounds containing adjacent quaternary carbon centers

Abstract

The application discloses a synthesis method of gem-diboron compound containing adjacent quaternary carbon center and relates to the technical field of organic synthesis. The synthesis method comprises the following steps: (1) under the protection of inert gas, dissolving the gem-diboron compound in tetrahydrofuran, adding tetramethylpiperidyl lithium, stirring for 5 minutes at room temperature, and preparing a gem-diboron lithium solution; (2) under the protection of inert gas, adding 2,6-di-tert-butyl-4-(diphenyl methylene) cyclohex-2,5-diene-1-ketone, stirring for 15 minutes at room temperature, carrying out silica gel column purification after the reaction is completed, and using a mixture of petroleum ether and ethyl acetate as an eluent, so as to obtain the gem-diboron compound containing adjacent quaternary carbon center. The application uses tetramethylpiperidyl lithium as an alkali, is simple and easy to obtain the gem-diboron reagent and is low in cost. Meanwhile, the application carries out the reaction at room temperature, is simple to operate, is mild in reaction, is environmentally friendly and safe, and is conducive to industrial large-scale production.

Description

Technical Field

[0001] This invention belongs to the field of compound preparation technology, and particularly relates to the field of synthesis technology of compounds containing adjacent quaternary carbon centers, specifically to a method for preparing geminal diborone compounds containing adjacent quaternary carbon centers. Background Technology

[0002] In recent years, geminal diboron compounds have attracted widespread attention and application in organic chemistry, materials chemistry, and pharmaceutical chemistry due to their excellent stability and transformability. However, current methods for synthesizing geminal diboron reagents with alkyl substitution at the a-position are limited to constructing simple primary or secondary alkane groups, and most are achieved using transition metal catalysis, with demanding synthesis conditions and high costs. Synthetic methods for geminal diboron reagents containing adjacent quaternary carbon centers have not yet been reported. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for synthesizing geminiboron compounds containing adjacent quaternary carbon centers. The synthetic route of this method is as follows:

[0004]

[0005] This invention is achieved using the following technical solution:

[0006] A method for synthesizing a compound containing adjacent quaternary carbon diboron includes the following steps:

[0007] (1) Under the protection of an inert gas, the geminal diborone compound was dissolved in tetrahydrofuran, and tetramethylpiperidine lithium was added and stirred at room temperature to obtain a geminal diborone lithium solution;

[0008] (2) Under inert gas protection, 2,6-di-tert-butyl-4-(diphenylmethylene)cyclohex-2,5-dien-1-one was added and stirred at room temperature for addition reaction. After the reaction was completed, silica gel column purification was performed to obtain gem-boron compounds containing adjacent quaternary carbon centers.

[0009] Preferably, the geminal diboron compound has the following structural formula:

[0010]

[0011] In the formula R 2 Selected from hydrogen atoms, alkyl, alkenyl, and allyl groups.

[0012] Preferably, the structural formula of the p-methylquinone compound is as follows:

[0013]

[0014] In the formula R 1R is selected from hydrogen atom, substituted phenyl, cyano, and R is selected from methyl, isopropyl, tert-butyl.

[0015] Preferably, the molar ratio of the geminiboron compound to the p-methylquinone compound is 2:1.

[0016] Preferably, the molar ratio of the tetramethylpiperidine lithium to the geminionitrile compound is 1:1.

[0017] Preferably, the stirring addition reaction time in step (2) is 15 minutes.

[0018] Preferably, in step (2), the volume ratio of petroleum ether to ethyl acetate in the eluent is 100:1.

[0019] The present invention also provides a geminal diborone compound containing adjacent quaternary carbon centers, the structural formula of which is as follows:

[0020]

[0021] Compared with the prior art, the technical effects of the present invention are as follows:

[0022] This invention uses lithium tetramethylpiperidin as a base, readily available gem-boron reagents, and 2,6-di-tert-butyl-4-(diphenylmethylene)cyclohexyl-2,5-dien-1-one as raw materials. The product is singular, with no byproducts, facilitating separation and purification, resulting in low production costs and excellent atom economy. Furthermore, the reaction is carried out at room temperature, making it easy to operate, mild, environmentally friendly, and suitable for large-scale industrial production. It can efficiently and in high yields produce high-purity gem-boron compounds containing adjacent quaternary carbon centers. Detailed Implementation

[0023] To make the objectives, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of the present invention will be thorough and complete.

[0024] Example 1

[0025]

[0026] The specific synthesis method is as follows:

[0027] In a glove box (under nitrogen protection), 0.4 mmol of methyl-substituted geminitrogen reagent, 1.0 mL of tetrahydrofuran, and 0.3 mmol of LiTMP (tetramethylpiperidine lithium) were mixed thoroughly. Then, 0.2 mmol of 2,6-di-tert-butyl-4-(diphenylmethylene)cyclohexane-2,5-dien-1-one was added to a sealed reaction tube. The mixture was stirred at room temperature for 15 minutes. The reaction solution was removed from the sealed reaction tube and purified by silica gel column chromatography. The product was obtained by elution with petroleum ether:ethyl acetate = 100:1 (v / v) in 78% yield.

[0028] Example 2

[0029]

[0030] The specific synthesis method is as follows:

[0031] In a glove box (under nitrogen protection), 0.4 mmol of benzyldiboron, 1.0 mL of tetrahydrofuran, and 0.3 mmol of LiTMP (tetramethylpiperidine lithium) were mixed thoroughly. Then, 0.2 mmol of 2,6-di-tert-butyl-4-(2-fluorophenylphenylmethylene)cyclohexane-2,5-dien-1-one was added to a sealed reaction tube. The mixture was stirred at room temperature for 15 minutes. The reaction solution was removed from the sealed reaction tube and purified by silica gel column chromatography. The product was obtained by elution with petroleum ether:ethyl acetate = 100:1 (v / v) in a yield of 57%.

[0032] In other embodiments, similar compounds were synthesized by adjusting the structures of the geminal diborone compound and the p-methylquinone compound according to the method of Example 1, as shown in Table 1.

[0033] Table 1

[0034]

[0035]

[0036]

[0037] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for synthesizing a geminiboron compound containing adjacent quaternary carbon centers, characterized in that, ， Includes the following steps: (1) Under nitrogen protection, 0.4 mmol of methyl-substituted geminitrogen reagent, 1.0 mL of tetrahydrofuran and 0.3 mmol of LiTMP were mixed evenly to obtain a geminitrogen lithium solution; (2) Under nitrogen protection, 0.2 mmol of 2,6-di-tert-butyl-4-(diphenylmethylene)cyclohexane-2,5-dien-1-one was added to a sealed reaction tube and stirred at room temperature for 15 minutes. The reaction solution was taken out from the sealed reaction tube and purified by silica gel column chromatography. The solution was eluted with petroleum ether and ethyl acetate in a volume ratio of 100:1 to obtain a geminal diborone compound containing adjacent quaternary carbon centers.

2. The method for synthesizing the geminiboron compound containing adjacent quaternary carbon centers according to claim 1, characterized in that, ， Includes the following steps: (1) Under nitrogen protection, 0.4 mmol benzyl diboron, 1.0 mL tetrahydrofuran and 0.3 mmol LiTMP were mixed evenly to obtain a lithium diboron solution; (2) Under nitrogen protection, 0.2 mmol of 2,6-di-tert-butyl-4-(2-fluorophenylphenylmethylene)cyclohexane-2,5-dien-1-one was added to a sealed reaction tube and stirred at room temperature for 15 minutes. The reaction solution was taken out from the sealed reaction tube and purified by silica gel column chromatography. The solution was eluted with petroleum ether and ethyl acetate in a volume ratio of 100:1 to obtain a geminal diborone compound containing adjacent quaternary carbon centers.

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