CN111943908A - Method for preparing isobutylamido thiazolyl resorcinol - Google Patents

Method for preparing isobutylamido thiazolyl resorcinol Download PDF

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CN111943908A
CN111943908A CN202010855517.4A CN202010855517A CN111943908A CN 111943908 A CN111943908 A CN 111943908A CN 202010855517 A CN202010855517 A CN 202010855517A CN 111943908 A CN111943908 A CN 111943908A
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resorcinol
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isobutyramidothiazolyl
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帅继山
华晓光
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Taizhou Ruishi Nuo Pharmaceutical Technology Co ltd
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    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D277/00—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings
    • C07D277/02—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings
    • C07D277/20—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members
    • C07D277/32—Heterocyclic compounds containing 1,3-thiazole or hydrogenated 1,3-thiazole rings not condensed with other rings having two or three double bonds between ring members or between ring members and non-ring members with hetero atoms or with carbon atoms having three bonds to hetero atoms with at the most one bond to halogen, e.g. ester or nitrile radicals, directly attached to ring carbon atoms
    • C07D277/38—Nitrogen atoms
    • C07D277/44—Acylated amino or imino radicals
    • C07D277/46—Acylated amino or imino radicals by carboxylic acids, or sulfur or nitrogen analogues thereof

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Abstract

The invention discloses a method for preparing isobutylamido thiazolyl resorcinol, which comprises the following steps: (1) reacting resorcinol with bromoacetic acid under the action of a catalyst to generate an intermediate shown in a formula I; (2) thiourea reacts with isobutyryl chloride to generate an intermediate shown in a formula II; (3) reacting the intermediate shown in the formula I with the intermediate shown in the formula II under the action of alkali to generate isobutyramide thiazolyl resorcinol shown in the formula III. The synthesis steps provided by the invention are simplified to three steps of reaction, the process route is simple, the raw materials are easy to obtain, the reaction time is short, the post-treatment is simple and convenient, the purity is more than 99%, the total yield is more than 29.1%, the operation is simple, and the method is suitable for continuous industrial production.

Description

Method for preparing isobutylamido thiazolyl resorcinol
Technical Field
The invention belongs to the field of chemical synthesis, and particularly relates to a method for preparing isobutylamido thiazolyl resorcinol.
Background
Thiamidol, also called isobutyramide thiazolyl resorcinol, belongs to resorcinol derivatives, can effectively inhibit the generation of tyrosinase, and can directly inhibit melanin from the root. The effective content of 0.2 percent of the compound has proved to have obvious effect in human body, and the key function is as follows: 1. reduce melanin production; 2. inhibiting pigment transport to keratinocytes. The resorcinol series applied in China at present are as follows: 4-butyl resorcinol, 4-hexyl resorcinol and 4-phenethyl resorcinol, but 4-butyl resorcinol and 4-hexyl resorcinol have low melting points and are easy to discolor, and in practical application, adverse reactions such as black turning, irritation and the like can be caused due to the selection of the addition amount, and the 4-phenethyl resorcinol has the defect of limit of the addition amount. Thiamidol can avoid the instability and side effects of the product in practical application. At present, how to simply prepare high-purity substances is a difficult problem in the development and popularization processes of the product.
The existing method for preparing Thiamidol is to protect hydroxyl by taking 2, 4-dihydroxy acetophenone as a raw material, halogenate an alfacarbonyl position to generate an intermediate A, react thiourea with isobutyryl chloride to generate an intermediate B, and finally perform cyclization and deprotection on the intermediate A and the intermediate B, which is fully embodied in US2014/121250 and US 2016/15615. However, the prior art has the following problems: 1.2, 4-dihydroxy acetophenone is expensive; 2. methyl chloroacetate is used as a hydroxyl protecting group, so that the dosage is large and the cost is increased due to a highly toxic product; 3. after thiourea and isobutyryl chloride react, the post-treatment is very inconvenient; the overall process has long steps and high cost of 4. when bromine is subjected to the alpha-carbonyl bromination, the toxicity is high, the corrosion is strong, the three wastes are difficult to treat, and the side reactions are more; 5. large amount of hydrochloric acid is needed for deprotection, and the method has many acidic waste water and is not environment-friendly. The core of the whole route is how to synthesize the bromination at the alphacarbonyl position easily. Therefore, there is a need to develop a new method for preparing Thiamidol.
Disclosure of Invention
The purpose of the invention is as follows: the invention aims to solve the technical problem of providing a method for preparing isobutyramidothiazolyl resorcinol aiming at the defects of the prior art.
In order to solve the technical problem, the invention discloses a method for preparing isobutylamido thiazolyl resorcinol, which comprises the following steps:
(1) carrying out Friedel-crafts acylation reaction on resorcinol and bromoacetic acid under the action of a catalyst to obtain a reaction solution containing an intermediate shown in a formula I;
(2) thiourea reacts with isobutyryl chloride to generate an intermediate shown in a formula II;
(3) performing cyclization reaction on the intermediate shown in the formula I and the intermediate shown in the formula II under the action of alkali to generate isobutyramide thiazolyl resorcinol shown in the formula III;
Figure BDA0002646279870000021
in the step (1), the catalyst is boron trifluoride diethyl etherate solution (liquid); wherein the mass concentration of boron trifluoride in the boron trifluoride diethyl etherate solution is 48%; the mol ratio of the resorcinol to the bromoacetic acid to the catalyst is 1: 0.5-1.5: 1-3, preferably 1:0.75: 1.
In the step (1), the reaction temperature is 0-75 ℃, preferably 70-75 ℃, and more preferably 75 ℃; the reaction was stopped when the molar content of bromoacetic acid was below 1%.
When the reaction temperature exceeds 65 ℃, the reaction is preferably heated to 65 ℃ for reaction for a period of time and then heated to the temperature required by the reaction, so that unsafe factors such as material spraying and the like caused by instant reaction of the system are prevented.
In the step (1), after the reaction is finished, slowly adding ice water into the reaction liquid cooled to room temperature, stirring, separating, drying the organic phase, further concentrating to dryness, and separating the concentrate by column chromatography to obtain the intermediate shown in the formula I.
Wherein the amount of the ice water is 1-4 times of the mass of the resorcinol; the stirring time is 5-20 min; the column chromatography is carried out by petroleum ether: ethyl acetate 50: 1, column chromatography separation.
In the step (2), the molar ratio of thiourea to isobutyryl chloride is 1-1.3: 1, preferably 1.25: 1; .
In the step (2), the solvent for the reaction is any one or the combination of two of dichloromethane and toluene; the concentration of isobutyryl chloride is 2-5 mol/L, preferably 3.13 mol/L.
In the step (2), the temperature of the reaction is 100-120 ℃, and preferably 115 ℃; the reaction was stopped when the molar content of isobutyryl chloride was below 1%.
In the step (2), after the reaction is finished, adding water into the reaction solution, distilling, cooling, crystallizing and filtering to obtain the intermediate shown in the formula II.
Wherein the amount of water is equal to the volume of toluene; the purpose of the distillation is to remove toluene.
In the step (3), the alkali is any one or a combination of sodium hydroxide, sodium carbonate and sodium bicarbonate, and is preferably sodium bicarbonate.
In the step (3), the molar ratio of the intermediate shown in the formula I to the intermediate shown in the formula II to the alkali is 1: 1-1.5: 1.5-2.5, preferably 1: 1.05: 1.5.
in the step (3), the solvent for the reaction is any one of methanol and ethanol, preferably ethanol; the concentration of the intermediate shown in the formula I is 0.1-0.5 kg/L, and preferably 0.2 kg/L.
In the step (3), the reaction temperature is 60-80 ℃, and preferably 80 ℃; the reaction was stopped when the 1 molar content of intermediate was less than 1%.
In the step (3), after the reaction is finished, filtering the reaction solution, concentrating the filtrate to be dry, adding ethyl acetate (the volume of which is 2-5 times that of the intermediate I), pulping (stirring), cooling and filtering to obtain Thiamidol.
Has the advantages that: compared with the prior art, the invention has the following advantages:
(1) the synthesis process provided by the invention has the advantages of simple route, easily obtained raw materials, short reaction time, simple and convenient post-treatment, purity of over 99 percent, total yield of over 29.1 percent, simple operation and suitability for industrial production.
(2) The operation steps of the invention are simplified to three steps of reaction, the continuous operation is easy for industrialized production, although the overall yield is only 1% -2% higher than that of the prior art, the price of the initial raw materials is low and the raw materials are easy to obtain, and the reaction steps are fewer, and each reaction has no special requirement.
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The foregoing and/or other advantages of the invention will become further apparent from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
FIG. 1 is a nuclear magnetic hydrogen spectrum of intermediate I of example 1.
FIG. 2 is a nuclear magnetic hydrogen spectrum of Thiamidol, a product of example 3.
FIG. 3 is a mass spectrum of Thiamidol, a product of example 3.
Detailed Description
Example 1: synthesis of intermediate I
Weighing 2220 g of resorcinol, 2100 g of bromoacetic acid and 5500mL of 48% boron trifluoride diethyl etherate solution, respectively adding into a 10L reaction bottle, slowly heating to 75 ℃ (heating to 65 ℃ for reaction for 30min, then heating to 75 ℃ for continuous reaction), and absorbing tail gas with aqueous solution of sodium hydroxide. After the reaction time reaches 3 hours, the liquid phase tracks the content of bromoacetic acid, and after the content is less than 1 percent, the solution is cooled to room temperature, 3000 milliliters of ice water is slowly dripped, the solution is stirred for 10 minutes, liquid separation is carried out, an organic phase is dried, and the organic phase is concentrated to obtain about 2900 grams of oily matter. The oil was purified by passing petroleum ether: ethyl acetate 50: 1 column chromatography separation to obtain about 1800 g of off-white to light yellow solid, the purity is more than 98 percent, and the yield is 51 percent.
Example 2: synthesis of intermediate II
Weighing 1000 g of isobutyryl chloride, 893 g of thiourea and 3L of toluene, respectively adding the isobutyryl chloride, the thiourea and the toluene into a 5L reaction bottle, carrying out reflux reaction at 115 ℃ for 3-4 hours, tracking a liquid phase, absorbing tail gas by using an aqueous solution of sodium hydroxide, adding 3L of water after the reaction is finished, distilling the toluene, and cooling for crystallization. Filtration gave about 900 g of a yellow crystalline solid with a purity of greater than 98% and a yield of about 65%.
Example 3: synthesis of Thiamidol
Weighing 500 g of an intermediate I, 333 g of an intermediate II, 2.5L of ethanol and 285 g of sodium bicarbonate, respectively adding the intermediate I, the intermediate II, the ethanol and the sodium bicarbonate into a 5L reaction bottle, slowly heating to 80 ℃, reacting for 30 minutes, tracking a liquid phase, filtering inorganic salt after the reaction is finished, concentrating organic matters, thermally pulping 1.5L of ethyl acetate, cooling, and filtering a product to obtain 530 g of white to off-white solid with the purity of more than 99 percent and the yield of about 88 percent.
Example 4:
222 g of resorcinol, 210 g of bromoacetic acid and 550mL of 48% boron trifluoride diethyl etherate solution are weighed and respectively added into a 2L reaction bottle, the temperature is heated to 55 ℃, and tail gas is absorbed by an aqueous solution of sodium hydroxide. After reacting for 3 hours, tracking the content of bromoacetic acid by the liquid phase to about 65%, maintaining the temperature, continuing to react for 8 hours, tracking the content of bromoacetic acid by the liquid phase to about 30%, cooling to room temperature, slowly dropwise adding 300 ml of ice water, stirring for 10 minutes, separating, drying the organic phase, and concentrating the organic phase to obtain about 200 g of oily matter. The oil was purified by passing petroleum ether: ethyl acetate 50: 1 column chromatography separation to obtain about 100 g of off-white to light yellow solid, the purity is more than 98 percent, and the yield is 28.3 percent.
Example 5:
222 g of resorcinol, 210 g of bromoacetic acid and 550mL of 48% boron trifluoride diethyl etherate solution are weighed and respectively added into a 2L reaction bottle, the temperature is heated to 65 ℃, and tail gas is absorbed by an aqueous solution of sodium hydroxide. After reacting for 3 hours, tracking the content of bromoacetic acid by the liquid phase to about 45%, maintaining the temperature, continuing to react for 8 hours, tracking the content of bromoacetic acid by the liquid phase to about 5%, cooling to room temperature, slowly dropwise adding 300 ml of ice water, stirring for 10 minutes, separating liquid, drying the organic phase, and concentrating the organic phase to obtain about 270 g of oily matter. The oil was purified by passing petroleum ether: ethyl acetate 50: 1 column chromatography separation to obtain about 155 g of off-white to light yellow solid, the purity is more than 98 percent, and the yield is 43.9 percent.
Comparative example 1
Weighing 222 g of resorcinol, 210 g of bromoacetic acid and 550mL of 48% boron trifluoride diethyl etherate solution, respectively adding the resorcinol, the bromoacetic acid and the 48% boron trifluoride diethyl etherate solution into a 2L reaction bottle, heating the mixture to 80 ℃, absorbing tail gas by using a sodium hydroxide aqueous solution, and instantly reacting reaction liquid to cause material spraying, which is not in line with production safety.
Comparative example 2: when resorcinol, bromoacetic acid and aluminum trichloride are taken as raw materials
Weighing 22.2 g of resorcinol, 50 g of aluminum trichloride and 200mL of dichloromethane, respectively adding the resorcinol, the aluminum trichloride and the dichloromethane into a 500-mL reaction bottle, cooling to 0 ℃, controlling the temperature within 5 ℃, adding 30 g of bromoacetic acid, and absorbing tail gas by using a sodium hydroxide aqueous solution. TLC spot plate tracking, and using aldehyde ketone indicator 2, 4-dinitrophenylhydrazine, no color development, experiment is not established.
Comparative example 3: when resorcinol, bromoacetic acid and zinc chloride are used as raw materials
22.2 g of resorcinol, 50 g of zinc chloride and 200mL of toluene are weighed and respectively added into a 500mL reaction bottle, 30 g of bromoacetic acid is added, reflux reaction is carried out, and tail gas is absorbed by aqueous solution of sodium hydroxide. TLC spot plate tracking, no reaction, experiment is not established.
Comparative example 4: when resorcinol, bromoacetyl bromide and aluminum trichloride are taken as raw materials
Weighing 22.2 g of resorcinol, 50 g of aluminum trichloride and 200mL of dichloromethane, respectively adding the resorcinol, the aluminum trichloride and the dichloromethane into a 500-mL reaction bottle, cooling to 0 ℃, dropwise adding 40 g of bromoacetyl bromide, controlling the temperature within 5 ℃, and absorbing tail gas by using an aqueous solution of sodium hydroxide. TLC point plate tracking, and using aldehyde ketone indicator 2, 4-dinitrophenylhydrazine, there is color development, but the main product is not intermediate 1, the reaction solution is very miscellaneous, the experiment is not true.
Comparative example 5: when resorcinol, bromoacetyl bromide and zinc chloride are used as raw materials
Weighing 22.2 g of resorcinol, 50 g of zinc chloride and 200mL of toluene, respectively adding into a 500mL reaction bottle, dropwise adding 40 g of bromoacetyl bromide, carrying out reflux reaction, and absorbing tail gas by using an aqueous solution of sodium hydroxide. TLC spot plate tracking generates single product, and uses aldehyde ketone indicator 2, 4-dinitrophenyl hydrazine, no color development experiment is not established.
Comparative example 6: using m-phenyl dimethyl ether, aluminium trichloride and bromoacetic acid as raw materials
Weighing 20 g of m-phenyl dimethyl ether, 35 g of aluminum trichloride and 200ml of dichloromethane, respectively adding the materials into a 500ml reaction bottle, cooling to 0 ℃, controlling the temperature within 5 ℃, adding 21 g of bromoacetic acid, reacting for 6 hours, adding water for quenching after TLC (thin layer chromatography) plate tracing, separating, concentrating an organic phase to dryness, adding 40 ml of petroleum ether and 20 ml of ethyl acetate mixed solvent for recrystallization to obtain about 20 g of white solid of 2-bromo-2, 4-dimethoxyacetophenone with purity of more than 98%.
Comparative example 7: 2-bromo-2, 4-dimethoxyacetophenone and boron tribromide are taken as raw materials;
weighing 5 g of 2-bromo-2, 4-dimethoxyacetophenone and 50ml of dichloromethane, cooling to 0 ℃ under the protection of nitrogen, adding 30 ml of a 1mol/L dichloromethane solution of boron tribromide, reacting at room temperature overnight, quenching with ice water, extracting with 50ml of ethyl acetate, concentrating the organic phase, and performing silica gel chromatography (petroleum ether: ethyl acetate: 50: 1) to obtain about 0.8 g of product intermediate I with the yield of about 18.2%.
Through the comparison examples, it can be seen that good products can not be obtained in the process of synthesizing the intermediate I by using resorcinol, bromoacetic acid (bromoacetyl bromide) and aluminum trichloride (zinc chloride) as parallel tests, and good products can be obtained when the phenolic hydroxyl of resorcinol is methylated and then subjected to Friedel-crafts acylation, but the reaction is difficult to carry out in the process of demethylation in the later period, so that the amplification synthesis is not facilitated.
The present invention provides a method and a concept for preparing isobutyramidothiazolyl resorcinol, and a method and a way for implementing the technical scheme are many, the above description is only a preferred embodiment of the present invention, it should be noted that, for those skilled in the art, a plurality of modifications and embellishments can be made without departing from the principle of the present invention, and these modifications and embellishments should also be regarded as the protection scope of the present invention. All the components not specified in the present embodiment can be realized by the prior art.

Claims (10)

1. A method for preparing isobutanoylaminothiazolyl resorcinol is characterized by comprising the following steps:
(1) reacting resorcinol with bromoacetic acid under the action of a catalyst to generate an intermediate shown in a formula I;
(2) thiourea reacts with isobutyryl chloride to generate an intermediate shown in a formula II;
(3) reacting an intermediate shown in a formula I with an intermediate shown in a formula II under the action of alkali to generate isobutyramide thiazolyl resorcinol shown in a formula III;
Figure FDA0002646279860000011
2. the process for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein in the step (1), the catalyst is boron trifluoride diethyl etherate; the mol ratio of the resorcinol to the bromoacetic acid to the catalyst is 1: 0.5-1.5: 1-3.
3. The process for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein the temperature of the reaction in step (1) is 0-75 ℃.
4. The method for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein the molar ratio of thiourea to isobutyryl chloride in step (2) is 1-1.3: 1.
5. the process for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein in the step (2), the solvent for the reaction is any one or two of dichloromethane and toluene; the concentration of isobutyryl chloride is 2-5 mol/L.
6. The method for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein the temperature of the reaction in step (2) is 100-120 ℃.
7. The method for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein in the step (3), the alkali is any one or a combination of sodium hydroxide, sodium carbonate and sodium bicarbonate.
8. The process for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein in the step (3), the molar ratio of the intermediate represented by the formula I, the intermediate represented by the formula II and the base is 1: 1-1.5: 1.5-2.5.
9. The process for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein in the step (3), the solvent of the reaction is any one of methanol and ethanol; controlling the dosage of the solvent to ensure that the concentration of the intermediate shown in the formula I is 0.1-0.5 kg/L.
10. The method for preparing isobutyramidothiazolyl resorcinol according to claim 1, wherein the temperature of the reaction in the step (3) is 60-80 ℃.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116554122A (en) * 2023-06-29 2023-08-08 南京桦冠生物技术有限公司 Alpha-keto acid amide or substituted oxalic acid amide ester compound and composition thereof

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CN105050664A (en) * 2013-03-11 2015-11-11 拜尔斯道夫股份有限公司 Combination of alkylamidothiazoles and uv-filter substances

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Publication number Priority date Publication date Assignee Title
CN116554122A (en) * 2023-06-29 2023-08-08 南京桦冠生物技术有限公司 Alpha-keto acid amide or substituted oxalic acid amide ester compound and composition thereof
CN116554122B (en) * 2023-06-29 2023-09-19 南京桦冠生物技术有限公司 Alpha-keto acid amide or substituted oxalic acid amide ester compound and composition thereof

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