TW201217355A - characterized by having 50% higher yield than that in literature, simplifying synthesis flow to be suitable for mass production and providing target compound in a purity of greater than 99% to directly prepare DCJTB - Google Patents

Abstract

The present invention provides a synthesis method of 2-methyl-6-tert-butyl-4-dicyanomethylene-4H-pyran, which belongs to the field of organic synthesis and includes the following steps: (1) reacting 2-methyl-6-tert-butyl-pyrone with malononitrile under the reflux state in the solution of the acetic anhydride until the reaction is complete (detected by TLC); and (2) condensing the reaction solution and adding an alcohol solvent for recrystallization. The synthesis method of present invention has 50% higher yield than that in literature, and provides a high-purity compound suitable to prepare DCJTB. In post-treatment process, this method directly uses an alcohol solvent to recrystallize the residues obtained after condensation, thereby bypassing a column chromatography process in original literature, simplifying synthesis flow to be suitable for mass production.

Description

201217355 VI. Description of the Invention: [Technical Field] The present invention relates to the synthesis of key intermediates of DCJTB, a red-light doping material, in the field of organic synthesis, in particular, 2-methyl-6-tert-butyl A method for synthesizing -4-dicyanomethyl-4H-pyran. [Prior Art] Organic electroluminescent devices have high efficiency and are capable of producing luminescent colors covering the entire visible light region, and have great application prospects in flat panel display technology. Due to the outstanding performance of organic electroluminescent diodes and the great application prospects in flat panel display technology, people have paid great attention to them. In order to realize color display, it is necessary to develop a series of three-color luminescent materials with high luminous efficiency and excellent performance. After more than ten years of intensive research, green light and blue materials with high brightness and high efficiency have been developed, but red light materials meet relatively few requirements. In the field of organic electroluminescence, the most widely used intramolecular charge transfer type red light dye is DCM series dye. In 1989, Tang et al. reported the use of 8-hydroxyquinoline aluminum Alq3 as the main hair *MW (CHChen, Tang, CW, J. Shi, Thinsolid Films, 2000, 363, 327-331), DCM1 and DCJ are high-efficiency red light-emitting devices for guest luminescent materials. Since then, DCM class 201217355 red luminescent dyes have been extensively studied and applied to devices. However, DCM and DCJ have the disadvantage of concentration fragmentation in device applications. For this reason, 'Tang et al. modified DCJ, and they replaced the compound DCJT at the C-1 and C-4 positions of julolidine. Although DCJT has good electroluminescence properties, its synthesis and purification separation process has great problems due to the reaction precursor 2,6-dimethyl-(4-dicarbonitrile) used in the synthesis process. The alkenyl)-4H pyran contains two reactive methyl groups, so DCJT will be further condensed with the aldehyde during the synthesis to form a dicondensed by-product 4 (dicyanomethyl-2,6-bis (julonidine- 9-vinyl)-4H-pyran (bis - DCJT). The formation of the secondary condensation by-product not only leads to a decrease in the reaction yield, but also makes the separation and purification of the product difficult. For the problems in the synthesis process, Chen et al. DCJTB was designed. Due to the improved synthesis method, the synthesis and purification of the compound have good red luminescence properties (Chin H. Chen, CWTang, J. Shi, US5935720·). DCJTB is the most successful material in the red light material. Brightness, efficiency, and longevity meet commercial applications. 'A method for synthesizing red-light doping material DCJTB is provided in US Patent No. 593,572, which is formed by docking two intermediates, one is 2-methyl-6-un Butyl _4_difluoromethyl-4H-pyridyl One is 1,1,7,7-tetramethyl guolinone awakened. Among them, 1 ' 7 ' 7 · tetramethyl · 9 _ jiluoniidine with the solution was solved 201217355, only 2-A The yield of the base-6-tert-butyl-4-dicyanomethyl-4H-pyran intermediate is very low, which makes the industrial cost of DCJTB high, and is also limited in OLED preparation applications, so 2-methyl-6 The -tert-butyl-4-dicyanomethylene-4H-pyran intermediate becomes the bottleneck for the industrialization of DCJTB. Due to the main intermediate 2-methyl-6-tert-butyl-4-dicyanomethylene-4H- In the synthesis process of pyran (see the following formula), the yield per step is very low, and the price of DCJTB synthesized is very expensive, which limits the use of DCJTB. To promote DCJTB, the intermediate 2-methyl-6-tertidine 4--4-cyanoalkenyl-4H-pyran (E in the formula), 5,5-dimethyl-2,4-hexanedialdehyde-0,0-boron difluoride (in the formula B), 7-Dimethylamino-2,2-dimethyl-6-ene-3,5-octanedialdehyde_0,0-boron difluoride (in the formula C), 2-methyl-6-tert-butyl The synthesis process of ke-pyrone (in the formula D) has to be improved 0 201217355

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C

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SUMMARY OF THE INVENTION On the basis of the above patents, the present invention provides a synthesis method of a kind of 2-methyl- 6-tert-butyl-4-dicyanomethylalkenyl-4, which has a higher yield than the literature. - Semi-over, hungry, can be used in the synthesis of DCJTB 〇2 methyl 6-tert-butyldicyanoyl-4H-pyran, including the following steps: 10 [Si 201217355 (1) 2- The keto-6-tert-butyl-pyrone is reacted with malononitrile in a solution of acetic anhydride under reflux. (2) After the reaction is completed, the reaction solution is concentrated, and re-crystallization is carried out by adding an alcohol solvent. The alcohol solvent is one or a mixture of methanol, ethanol, isopropanol, and butanol. The molar ratio of 2-methyl-6-tert-butyl-pyridone to malononitrile was 1:2. The reaction time of the step (1) is 6-15 hours. Preferably, the reaction time is 8 hours. The reaction was completely tested by TLC. The reaction mechanism of the present invention is that 2-methyl-6-tert-butyl-pyrone is reacted with malononitrile under the action of a water reducing agent acetic anhydride. The present invention adopts a reflux temperature control, and the boiling point of acetic anhydride is 139 ° C. Since water is generated, the reaction temperature is basically controlled to be 130 ° C or higher, the reaction speed is increased, and the TLC method is used to monitor the end point of the reaction, so that the reaction is more complete, so that the post-treatment of the present invention is relatively simple, and the post-treatment of the present invention is simple. The process is to recrystallize the concentrated residue directly with an alcohol solvent, eliminating the column chromatography process in the original literature, the yield is high and the purity is very good, reaching 99% or more, and can be used as a red light intermediate material, Laser material intermediates are used. The molar ratio of 201217355 2-methyl-6-tert-butyl-pyrone to malononitrile is preferably 1:2, since 2-methyl-6-tert-butyl ketone is not easily separated from the product, so the excess is used. The malononitrile is allowed to react completely, and the concentration can remove excess malononitrile and acetic anhydride. Therefore, the molar ratio of 2-methyl-tert-butyl-pyrone to malononitrile is preferably 1:2, so that 2- Methyl-6-tert-butyl-pyrone is completely reacted. The process of the invention is carried out as follows: • 2-methyl-6-tert-butyl-pyridinone, malononitrile, acetic anhydride reflux reaction for 6 to 15 hours, concentration and purification with alcohol; alcohol can be methanol, ethanol, One or a mixture of isopropanol and butanol. The synthetic process provided by this patent has the following characteristics compared with the process provided by the U.S. patent document: (1) The process yield provided by this patent is more than half of the literature, and the product purity is over 99%. # (2), the reaction conditions are mild, the process is simple, easy to produce, and low in cost. (3) The obtained product E has high purity and can be directly used for preparing DCJTB. [Embodiment] Hereinafter, embodiments of the present invention will be described by way of specific embodiments, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in the specification [S] 12 201217355. . The present invention will be further described in detail below with reference to the embodiments. 2-Methyl-6-tert-butyl-pyrone can be prepared according to the method disclosed in U.S. Patent 5,935, 720 (see Example 3). EXAMPLE 2 2-Methyl-6-tert-butyl-4-dicyanomethylene-4H-portomer in a 25 mL three-necked flask was charged with 2-methyl-6-tert-butyl-pyrone 2.21 g (0.01mol), propylene diacetate 2.04g (0.02mo), acetic anhydride 5mL mixed stirring 'heated reflux, TLC detection of the completion of the reaction (8 hours), stop heating 'spin dry mixture, add methanol to recrystallize twice, get 2.089 Light yellow solid (80%), purity 99% by HPLC. (US5935720 reported a yield of 50%)

Melting point: 108-110 ° C HMNR (CDC 13, 400 Hz): 1.31 (9H, s); 2.35 (3H, s); 6.57 (2H, d) Although the foregoing description and drawings have disclosed preferred embodiments of the invention It is to be understood that various additions, modifications and substitutions may be used in the preferred embodiments of the invention without departing from the spirit and scope of the principles of the invention as defined by the appended claims. It will be appreciated by those skilled in the art that the present invention can be used in many forms, structures, arrangements, proportions, materials, components and components 13 201217355. Therefore, the embodiments disclosed herein are to be considered as illustrative and not restrictive. The scope of the present invention should be defined by the scope of the appended claims, and the legal equivalents thereof are not limited to the foregoing description. [Simple description of the diagram] Μ J » ΝΝ [Description of main component symbols]

Claims (1)

201217355 VII. Patent application scope: 1. A method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethyl-4H-pyran, comprising the following steps: (1) 2-methyl-6 - tert-butyl-pyrone is reacted with malononitrile in a solution of acetic anhydride under reflux; (2) After the reaction is completed, the reaction solution is concentrated, and re-crystallization is carried out by adding an alcohol solvent. Φ 2. The method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethyl-4H-pyran according to claim 1, wherein the alcohol solvent is methanol, ethanol or isopropanol One or a mixture of butanol. 3. A method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethylenyl-4H-pyran as described in claim 1, wherein the 2-methyl-6-tert-butyl-pyridyl The molar ratio of ketone to malononitrile is 1:2. 4. The method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethyl-4H-pyran as described in claim 1, wherein the reaction time of the step (1) is 6-15 hours. . 5. A method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethyl- 4H-pyran as described in claim 4, wherein the reaction time is 8 hours. 6. A method for synthesizing 2-methyl-6-tert-butyl-4-dicyanomethylalkenyl- 4?--an as described in claim 1, which is completely detected by TLC. [S] 15