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The preparation method of 2-(aminophenyl)-5-aminobenzoxazole

A technology of aminobenzoxazole and nitrobenzoxazole, which is applied in the field of preparation of benzoxazole compounds, can solve the problem of reducing the reaction yield and product purity, the reaction yield is less than 40%, and it is not suitable for industrial production and other problems, to achieve the effect of low raw material cost, high reaction selectivity and low price

Active Publication Date: 2021-10-15
CHANGZHOU SUNLIGHT PHARMA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] The disadvantage of this method is: the yield is low, and the reaction yield of the middle two steps is less than 40%.
[0008] The deficiency of this method is: what condensation reaction obtains is double acylation intermediate, will reduce reaction yield and product purity greatly like this
[0012] However, the price of fluorine-containing monomers is relatively high, which is not suitable for industrial production

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1）

[0037] The preparation method of the 2-(aminophenyl)-5-aminobenzoxazole of the present embodiment has the following steps:

[0038] ①Add 200mL of xylene, 20mL of DMF and 35.2g of 2-amino-4-nitrophenolate sodium (0.2mol) into the condensation reaction kettle, and slowly add para The xylene solution of nitrobenzoyl chloride (containing 37.1g of p-nitrobenzoyl chloride and 100mL of xylene) was slowly heated to 95±2°C after dropping, and stirred until the reaction was complete.

[0039] After the reaction, cool down to 10-20°C, slowly add 100 mL of water, stir for 30 min, filter, wash the filter cake with 20 mL of water, separate the filtrate, combine the filter cake and the organic layer.

[0040] ②Add the combined filter cake and organic layer in step ① into the reaction flask, raise the temperature and reflux to separate the water, then add 0.5g of p-toluenesulfonic acid, and react until complete at a temperature of 125±2°C.

[0041] After the reaction, filter, add the filter ...

Embodiment 2～ Embodiment 6）

[0045] The preparation method of each embodiment is basically the same as that of Example 1, except for the first two steps, see Table 1 for details.

[0046] Table 1

[0047] Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 mixed with organic solvents Xylene+DMF Xylene+DMAc Xylene+NMP Toluene+DMF Toluene+DMAc Toluene+NMP condensation temperature 95±2℃ 102±2℃ 108±2℃ 65±2℃ 75±2℃ 85±2℃ ring temperature 125±2℃ 132±2℃ 138±2℃ 95±2℃ 105±2℃ 115±2℃ Nitro 52.5g 50.5g 49.6g 50.8g 48.3g 47.9g two-step yield 92.1% 88.6% 87.0% 89.1% 84.7% 84.0% purity 99.1% 98.6% 98.2% 99.0% 98.5% 98.0%

Embodiment 7）

[0049] The preparation method of the 2-(aminophenyl)-5-aminobenzoxazole of the present embodiment has the following steps:

[0050] ①Add 500mL of xylene, 48mL of DMF and 88.0g of 2-amino-4-nitrophenolate sodium (0.5mol) into the condensation reactor, and slowly add para The xylene solution of nitrobenzoyl chloride (which contains 92.8g of p-nitrobenzoyl chloride and 250mL of xylene), after dropping, slowly raise the temperature to 95±2°C, and stir until the reaction is complete.

[0051] After the reaction, cool down to 10-20°C, slowly add 250 mL of water, stir for 30 min, filter, wash the filter cake with 60 mL of water, separate the filtrate, combine the filter cake and the organic layer.

[0052] ②Add the combined filter cake and organic layer in step ① into the reaction flask, raise the temperature and reflux to separate the water, then add 1.25g of p-toluenesulfonic acid, and react until complete at a temperature of 125±2°C.

[0053] After the reaction, filter, add the f...

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Abstract

The invention discloses a preparation method of 2-(aminophenyl)-5-aminobenzoxazole, which comprises the following steps: ①Condensation of 2-amino-4-nitrophenol sodium and nitrobenzoyl chloride to obtain an ester Intermediate; ②The ester intermediate is cyclized under strong acid catalysis to obtain 2-(nitrophenyl)-5-nitrobenzoxazole; ③2-(nitrophenyl)-5-nitrobenzoxazole Under Pd / C catalysis, hydrogenation gives 2-(aminophenyl)-5-aminobenzoxazole. The present invention uses 2-amino-4-nitrophenolate sodium to condense with nitrobenzoyl chloride to generate only an acylation intermediate (that is, an ester intermediate) substituted by a hydroxyl site, while the amino site does not react with nitrobenzoyl chloride , so that no amide impurities are generated, the reaction selectivity is high, the condensation + ring closure yield is as high as about 90%, and the purity of nitro compounds is about 99%.

Description

technical field [0001] The invention belongs to the technical field of preparation of benzoxazole compounds, and in particular relates to a preparation method of 2-(aminophenyl)-5-aminobenzoxazole. Background technique [0002] OLED (Organic Light Emitting Diode) is a display that emits light automatically under the condition of current passing, mainly composed of organic layers, cathode and anode. Compared with traditional LCD and LED, OLED has the advantages of low driving voltage, active light emission, fast response, wide viewing angle, and large-area full-color panel display. It can be widely used in TVs, smart phones, smart wearables, VR, display , lighting and other fields, has broad market prospects. [0003] Due to the existence of π-π stacking and the interaction between π cations on the aromatic conjugation plane of the five-membered nitrogen-containing heterocyclic group of benzoxazole compounds, their benzene ring structure has high plasticity in chemical modif...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07D263/57
CPCC07D263/57
Inventor 胡国宜胡锦平吴建华张培锋
Owner CHANGZHOU SUNLIGHT PHARMA
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