A method for synthesizing 9,9-dimethyl-2-bromofluorene

Abstract

The present invention discloses a method for synthesizing 9,9-dimethyl-2-bromofluorene. The method uses 2-bromo-9-fluorenone and methylmagnesium chloride as raw materials, and further reacts them under the action of zirconium tetrachloride to obtain the final product, 9,9-dimethyl-2-bromofluorene. The method has the advantages of cheap and readily available raw materials, convenient production, and ease of purification, and can be developed into an industrial production method.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular to a method for synthesizing 9,9-dimethyl-2-bromofluorene. Background Art

[0002] 9,9-Dimethyl-2-bromofluorene is a key intermediate frequently used in drug development, chemical engineering, and optoelectronic materials. Currently, there are few reported synthetic methods for 9,9-dimethyl-2-bromofluorene, and these methods suffer from expensive raw materials and complex reactions, making them unsuitable for industrial production.

[0003] Therefore, developing a new synthesis method for 9,9-dimethyl-2-bromofluorene is of great significance to the industrial production of 9,9-dimethyl-2-bromofluorene. Summary of the Invention

[0004] The technical problem solved by the present invention is to provide a method for synthesizing 9,9-dimethyl-2-bromofluorene. The method of the present invention has the advantages of cheap and readily available raw materials, convenient production, environmental protection, safety, and easy purification.

[0005] To solve the above technical problems, the present invention adopts the following technical solution: a method for synthesizing 9,9-dimethyl-2-bromofluorene, the reaction formula of the synthesis method is:

[0006]

[0007] The synthesis method comprises the following steps:

[0008] Under an inert gas environment and in a solvent, 2-bromo-9-fluorenone and methylmagnesium chloride react with zirconium tetrachloride to prepare the final product 9,9-dimethyl-2-bromofluorene.

[0009] As an embodiment of the present invention, the molar equivalent ratio of 2-bromo-9-fluorenone to methylmagnesium chloride and zirconium tetrachloride is 1:(2-3):(2-5).

[0010] Preferably, the molar equivalent ratio of the 2-bromo-9-fluorenone to methylmagnesium chloride and zirconium tetrachloride is 1:2.2:2.5.

[0011] As an embodiment of the present invention, the solvent is selected from tetrahydrofuran, 2-methyltetrahydrofuran, diethyl ether, and methyl tert-butyl ether.

[0012] Preferably, the solvent is tetrahydrofuran.

[0013] As an embodiment of the present invention, the reaction temperature is -10 to 20°C.

[0014] Preferably, the reaction temperature is -5 to 10°C.

[0015] As an embodiment of the present invention, the inert gas is nitrogen.

[0016] The present invention provides a novel method for synthesizing 9,9-dimethyl-2-bromofluorene, using inexpensive and readily available 2-bromo-9-fluorenone and methylmagnesium chloride as raw materials. The final product, 9,9-dimethyl-2-bromofluorene, is obtained through a one-step reaction under the action of zirconium tetrachloride. This method has the advantages of inexpensive and readily available raw materials, convenient production, and ease of purification, and can be developed into an industrial production method. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described in detail below through examples.

[0018] Example 1

[0019] This embodiment provides a method for synthesizing 9,9-dimethyl-2-bromofluorene, comprising the following steps:

[0020] Under a nitrogen atmosphere, 2.59 g of 2-bromo-9-fluorenone was added to a three-necked flask, followed by 10 ml of tetrahydrofuran. Under nitrogen protection, the temperature of the reaction system was lowered to -5 degrees Celsius, and then 5.83 g of zirconium tetrachloride was added in batches while stirring. The temperature of the system was controlled not to exceed 0 degrees Celsius during the addition process. The mixture was then stirred at -5 degrees Celsius for 1 hour. 22 ml of a 1 mol / L methylmagnesium chloride solution was then slowly added dropwise, and the temperature of the reaction system was controlled not to exceed 0 degrees Celsius during the addition process. After the addition was complete, the mixture was reacted at 0 degrees Celsius for 6 hours, then heated to 10 degrees Celsius and reacted for another 5 hours. TLC monitored the reaction. After the reaction was complete, the reaction solution was cooled to 0 degrees Celsius and saturated aqueous ammonium chloride was added to quench the reaction. The reaction solution was extracted with dichloromethane, and the organic phase was washed with water. The organic phase was dried and spin-dried, and passed through a column to obtain 2.35 g of 9,9-dimethyl-2-bromofluorene product with a yield of 86.1%. The NMR of 9,9-dimethyl-2-bromofluorene is: 1 H NMR (CDCl3): δ7.69(m,1H),7.56(d,1H),7.55(d,1H),7.46(dd,1H),7.42(m,1H),7.34(m,2H),1.48(s,6H).

[0021] During the research process, the following experiments were also conducted. The preparation steps were referred to Example 1, and different reagent amounts and solvents were selected, as shown in Table 1 below.

[0022] Table 1

[0023]

[0024] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent transformations made using the contents of the present invention specification, or any direct or indirect application in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for synthesizing 9,9-dimethyl-2-bromofluorene, characterized in that: The reaction formula of the synthesis method is: The synthesis method comprises the following steps: Under an inert gas environment, in a solvent, 2-bromo-9-fluorenone and methylmagnesium chloride react with zirconium tetrachloride to prepare the final product 9,9-dimethyl-2-bromofluorene; The molar equivalent ratio of the 2-bromo-9-fluorenone to methylmagnesium chloride and zirconium tetrachloride is 1:2.2:2.5; and the solvent is selected from tetrahydrofuran or 2-methyltetrahydrofuran.

2. The synthesis method according to claim 1, wherein The reaction temperature is -10 to 20°C.

3. The synthesis method according to claim 2, characterized in that The reaction temperature is -5 to 10°C.

4. The synthesis method according to claim 1, characterized in that The inert gas is nitrogen.

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