38 results about "Dimethyl malonate" patented technology

The invention relates to a solvent-resistant medical connecting line sheath material and a preparation method thereof, and belongs to the technical field of high polymer materials. The sheath material is prepared from the following components: 38 to 44 weight percent of passivated toughening agent, 1.5 to 1.8 weight percent of heat stabilizer, 0.7 to 0.9 weight percent of lubricant, 0.12 to 0.15 weight percent of antioxidant and the balance of PVC (Polyvinyl Chloride) resin, the passivated toughening agent is prepared by the following steps: carrying out amine ester exchange reaction on 4-hydroxybutylamine and dimethyl difluoromalonate, introducing an alcohol-terminated hydroxyl group, carrying out substitution with dichloromethylvinylsilane to form a fluorine-containing chain compound, and finally carrying out double bond addition on methyl thioglycolate and a side chain; the passivation toughening agent is compatibilized through branched chain methyl ester and dynamically coordinated with a PVC molecular chain through a side chain thioether group, weakens the acting force between PVC chains, plays a good toughening role, inhibits dissolution through physical crosslinking, shields and passivates the PVC molecular chain, and relieves swelling of PVC in a solvent.

The invention belongs to the technical field of separation of drug intermediates, and particularly relates to a method for preparing a high-purity dipropylmalonic acid refined product by adding a polar solvent into a dipropylmalonic acid crude product, heating, pulping for a certain time, cooling, filtering and drying. Decarboxylating the refined dipropylmalonic acid product to obtain high-purity valproic acid; distilling the filtrate to recover the polar solvent to obtain 2-methyl-2-propylmalonic acid, and carrying out decarboxylation on the 2-methyl-2-propylmalonic acid to obtain 2-methylpentanoic acid; 2-methylvaleric acid is used as a perfume additive. According to the method disclosed by the invention, the process impurity 2-methyl-2-propylmalonic acid in dipropylmalonic acid is separated, and the process impurity 2-methylvaleric acid (EP-L) in valproic acid or sodium valproate is precisely separated; the quality of the valproic acid product prepared by the method disclosed by the invention meets the requirements of European Pharmacopoeia EP-11 (2023). According to the invention, the problems of quality control and process evaluation of valproic acid or sodium valproate prepared by a dimethyl malonate method are solved.

The invention discloses a synthesis method of 5-bromoindole-2-carboxylic acid methyl ester, and the synthesis route comprises the following steps: S1, taking 2-iodo-4-broronitrobenzene and dimethyl malonate as raw materials, and under the catalysis of a solid sulfonic acid resin catalyst, carrying out nucleophilic substitution reaction to prepare 2-(5-bromo-2-nitrophenyl) dimethyl malonate; s2, taking the dimethyl 2-(5-bromo-2-nitrophenyl) malonate prepared in the step S1 as a raw material, taking a ZSM-5 molecular sieve loaded with cobalt acetate as a catalyst, and introducing hydrogen for reduction reaction to prepare a 5-bromoindole-2-carboxylic acid methyl ester crude product; and S3, carrying out recrystallization on the 5-bromoindole-2-carboxylic acid methyl ester crude product prepared in the step S3 by using ethanol, so as to prepare a 5-bromoindole-2-carboxylic acid methyl ester pure product. The synthesis yield is relatively high, the environmental protection property is relatively good, and the prepared 5-bromoindole-2-carboxylic acid methyl ester is relatively excellent in quality and relatively low in cost.

The present invention relates to a method of adding an isocitrate lyase specific inhibitor to a lactic acid fermentation process to block the production of succinic acid as a byproduct of fermentation. The specific inhibitor includes a combination of one or more of glycolic acid methyl ester, malonic acid dimethyl ester, hydroxymalonic acid diethyl ester, 3-nitropropionic acid ethyl ester, mercuric chloride, or 5,5'-dithiobis(2-nitrobenzoic acid) to effectively reduce the amount of succinic acid in the lactic acid.

The invention discloses a gram-level synthesis method of Dactyllactone A. The gram-level synthesis method of Dactyllactone A is shown in the description. The method comprises the following steps: with simple and easily available aryl iodide, aziridine and triisopropyl silylacetylene as starting materials, stirring and reacting in an organic solvent at 60-70 DEG C under the action of a palladium catalyst, a phosphine ligand, a norbornene derivative and alkali to obtain a key intermediate; the key intermediate is condensed with iodo gem-dimethyl ester furanone prepared from propiolic acid and dimethyl malonate iodine ylide, and then the condensation product is subjected to an Au / Ag catalyzed intramolecular hydroamination reaction, photocatalytic 6-pi electro-cyclization and two-step conversion, so that the natural product Dactyllactone A can be obtained, wherein the iodo gem-dimethyl ester furanone and iodo gem-dimethyl ester furanone are prepared from propiolic acid and dimethyl malonate iodine ylide. The method has the advantages of cheap and easily available raw materials, short reaction steps, high reaction efficiency, large preparation scale, simple preparation process and the like, has great application potential, and lays a good foundation for industrial production.

This invention discloses a method for preparing a key intermediate of iodopyridine, using dimethyl malonate as a raw material, and sequentially undergoing dihydroxylation S1 → acetalization S2 → hydrolysis and acidification S3 → decarboxylation S4 to obtain iodopyridine. The raw materials of this invention are inexpensive and readily available in the market, and the reaction efficiency is high, improving the purity and yield of the product. Intermediates 1 and 2 obtained from the process do not require separation and purification operations and can be directly used in the next step of the reaction. The purification effect is significant, yielding intermediate products with a purity ≥99%, and the total yield of the five steps is as high as 65-70%, which is beneficial for large-scale production.

The present application relates to the preparation method of magnesium valproate shown in chemical structural formula I: under the action of potassium carbonate and PTC, dimethyl malonate is subjected to dipropylization with 1-chloropropane in DMF solvent to prepare dimethyl dipropyl malonate shown in formula III; III is subjected to hydrolysis reaction to prepare dipropyl malonic acid shown in formula II; II is uniformly mixed with magnesium oxide, and heated to prepare magnesium valproate shown in formula I by decarboxylation, and the total yield of magnesium valproate is not less than 90.0%; the preparation reaction is as follows: wherein, the PTC for dipropylization is selected from quaternary ammonium salt, the reaction temperature is 50-140 DEG C, the reaction time is 4.0-14.0 h; the hydrolysis temperature is 70-95 DEG C, the time is 2.0-4.0 h; the decarboxylation temperature is 140-158 DEG C, and the time is 3.0-5.0 h.

The application discloses a synthesis method of pimobendan, which comprises the following steps: a Friedel-Crafts acylation reaction: compound I and compound A are subjected to a Friedel-Crafts acylation reaction in aprotic solvent under the action of a Lewis acid to generate compound II; a substitution and hydrolysis reaction: under alkaline conditions, compound II and dimethyl malonate or diethyl malonate are subjected to a substitution reaction in an ether solvent, and the generated compound is subjected to a hydrolysis reaction in an alkaline aqueous solution to generate compound III; a decarboxylation and ring-closing reaction: compound III is heated under the condition of hydrazine hydrate and acid to generate compound IV; a substitution reaction: compound IV and an amine are subjected to a substitution reaction in a polar solvent to generate compound V; a reduction reaction: compound V is subjected to a reaction in an acidic aqueous solution of a protic solvent under the condition of palladium-carbon and hydrogen to generate compound VI; and a ring-closing reaction, so that the pimobendan is obtained. The method has high safety, short line steps and simple operation.

The present invention relates to the field of organic synthesis, and particularly relates to a new method for synthesizing 2-chloro-6-nitrotoluene. The synthesis method of 2-chloro-6-nitrotoluene provided by the present invention uses 2,3-dichloronitrobenzene (Compound 1) as a raw material, reacts with methyl cyanoacetate or dimethyl malonate under the action of a reaction solvent and an acid-binding agent to form Compound 2, and after filtration and decolorization, a dilute acid solution is added for de-esterification reaction to obtain Compound 3. Finally, the R group is removed in a dilute acid solution to obtain the final product 2-chloro-6-nitrotoluene (Compound 4). The synthesis method of 2-chloro-6-nitrotoluene described in the present invention has the advantages of simple operation, safety, economy, environmental friendliness, and low cost.

The invention relates to the field of biopesticides, in particular to a method for synthesizing sex pheromone of pinus tabulaeformis, which comprises the following steps: reacting 1-bromo-n-heptane (3) serving as an initial raw material with magnesium, and then reacting with (R)-epoxypropane (4) to obtain chiral alcohol 5; then reacting with paratoluensulfonyl chloride, and then reacting with dimethyl malonate to obtain malonate 7; carrying out sodium hydroxide catalytic hydrolysis and high-temperature decarboxylation to obtain an acid 8, and carrying out lithium aluminum hydride reduction and NBS bromination to obtain a chiral bromide 10; reacting with magnesium, and reacting with sulfonate 12 to obtain silyl ether 11; then carrying out TBAF deprotection to obtain chiral alcohol 13; and finally, reacting the chiral alcohol 13 with acetic acid to obtain acetic acid (2S, 3S, 7S)-3, 7-dimethyl-2-pentadecanol ester (1), and reacting the chiral alcohol 13 with propionic acid to obtain propionic acid (2S, 3S, 7S)-3, 7-dimethyl-2-pentadecanol ester (2). The method has the advantages of high total yield, low synthesis cost and the like.

Disclosed in the present invention is a process method for preparing fluopyram. The process method comprises the following steps: in the presence of a solvent 1, the compound potassium dimethyl 2-[3-chloro-5-(trifluoromethyl)pyridin-2-yl]malonate reacting with a compound 1-D in a reaction vessel to obtain an intermediate compound, then distilling, and recovering the solvent 1, wherein the intermediate compound does not need to be purified; then adding water, a base, and a solvent 2 to the reaction vessel for reaction; after the reaction is finished, adjusting the pH, and continuing reaction; and after the reaction is finished, performing work-up to obtain the product fluopyram. The solvent 1 is selected from acetate solvents having a boiling point ranging from 40ºC to 110ºC at room temperature and atmospheric pressure. The process method of the present invention is simple, has high overall yield, and low cost, the quality of the product is stable and meets standards, and fluopyram is prepared in one pot, thereby facilitating reduction of the number of production devices, reducing investment, reducing costs, and increasing efficiency, and facilitating large-scale commercial production.

The present application belongs to the field of gasoline additive, and particularly relates to an environment-friendly gasoline antiknock agent and a preparation method thereof. The antiknock agent comprises two newly designed modified compounds: 3,5-di-tert-butyl phenyl carborane carboxylate and 2-(dicyclohexyl phosphino)-1,2-oxaborinin-4-carboxylic acid iso-octyl ester. In the preparation, a cosolvent is first added into a reactor, and then the two modified compounds, polyisobutylene amine, isobutyl acetate and dimethyl malonate are sequentially added under an inert atmosphere. After mixing by continuous stirring, the temperature is raised, an antioxidant is added, and then stirring is continued. Finally, the product is obtained by cooling and filtering. The two modified compounds are prepared by condensation reaction of carborane carboxylic acid and steric phenol, esterification of oxaborinin carboxylic acid and iso-octanol, and then phosphination reaction. The antiknock agent does not contain metal elements, has biodegradable characteristics, can significantly improve the octane number of gasoline and reduce engine deposits and harmful gas emissions, and meets the green environmental protection requirements.

The invention discloses a method for synthesizing dimethyl malonate through homogeneous-phase continuous carbonylation, which comprises the following steps of: carrying out carbonylation reaction on chloracetate serving as a raw material at a certain temperature and pressure in the presence of a liquid acid-binding agent and a catalyst to synthesize the dimethyl malonate. The problems that in a batch process of a traditional dimethyl malonate carbonylation synthesis method, carbon monoxide in a reactor is high in pressure and large in consumption, and once leakage or other faults occur, great risks are brought to safety production are solved; the invention solves the technical problems in the prior art that an acid-binding agent is in a solid state before and after acid-binding, the solid content is high, if continuous production transformation is needed, the requirement for feeding and discharging conveying of equipment is high, large-scale production is not facilitated, and the product and a catalyst are difficult to separate and recover after the reaction is finished, so that the production cost is increased.

The invention belongs to the technical field of spice raw material synthesis, and particularly relates to a synthesis method of methyl cis-dihydrojasmonate, which comprises the following steps: dissolving 1-heptyne in toluene, discharging into a first reaction tank, adding a cobalt catalyst, and discharging 1-bromine-ethylene and carbon monoxide gas into the first reaction tank; adding triphenylphosphine into a first catalyst recovery tank, discharging catalyst precipitates, and carrying out sectional distillation to distill, cool and recover 1-heptyne; absolute methanol is discharged into the layering tank; dimethyl malonate is discharged into a second reaction tank, sodium methoxide is slowly added, an addition reaction is carried out at the temperature of-5 DEG C to 0 DEG C, and then heating is carried out for a decarboxylation reaction; 4-bromo-dihydrojasmonic acid methyl ester obtained by distillation is discharged into a third reaction tank; and discharging methyl jasmonate with alpha, beta-double bonds into a fourth reaction tank for reaction. By simplifying the steps, improving the recovery rate of the catalyst and realizing continuous production, the problems of high cost, low yield, low recovery rate of the catalyst and the like in preparation of the methyl cis-dihydrojasmonate in the prior art are solved.

This invention discloses a highly efficient method for synthesizing proxalutamide intermediates, belonging to the field of pharmaceutical synthesis technology. First, dimethyl malonate and 2-chloro-5-nitropyridine are used as raw materials, condensed in the presence of potassium carbonate to generate dimethyl 2-(5-nitropyridine-2-yl)malonate. This is then reacted with tert-butyl acrylate and acid-hydrolyzed to obtain 4-(5-nitropyridine-2-yl)butyric acid. After activation with N,N'-carbonyl diimidazole, it is coupled with aminoacetaldehyde dimethyl acetal to form N-(2,2-dimethoxyethyl)-4-(5-nitropyridine-2-yl)butyramide. Then, a cyclization reaction mediated by phosphorus pentoxide and methanesulfonic acid is used to generate crude 2-(3-(5-nitropyridine-2-yl)propyl)oxazole. After purification, the nitro group is reduced by catalytic hydrogenation, and finally, it reacts with 1,5-naphthalenedisulfonic acid to form a salt, yielding the proxalutamide intermediate. This method achieves highly efficient synthesis of proxalutamide intermediates.

The application discloses a preparation method of fluopyram, which comprises the following steps: step 1: in the presence of solvent 1 and a base, dimethyl malonate and 2,3-dichloro-5-trifluoromethyl pyridine are added to react, a salt reaction is carried out by adjusting pH, and 2-[3-chloro-5-(trifluoromethyl) pyridyl] dimethyl malonate potassium salt, namely intermediate 1, is obtained; step 2: o-trifluoromethyl benzoyl chloride, an organic base and chloromethylamine are added to react, and intermediate 2 is obtained; step 3: solvent 3, intermediate 1 and intermediate 2 are added to react, and intermediate 3 is obtained; step 4: water, a base, solvent 4 and intermediate 3 are added, pH is adjusted after reaction, and continuous reaction is carried out, and fluopyram is obtained. By adopting the preparation method, the yield of fluopyram is high, the purity is high, the reaction time is short, the reaction condition is mild, and the method is suitable for mass production.

The application discloses plant oil-containing insulating oil and a preparation method and application thereof, and belongs to the technical field of lubricating oil, and is used for solving the problems that plant oil-type insulating oil is prone to solidification at low temperature, and antioxidation stability and flame retardation need to be further improved in the prior art, wherein the preparation method of the plant oil-containing insulating oil comprises the following steps: uniformly mixing dimethyl 2-(4-aminophenyl)malonate and 4-(1-hydroxyethyl)-2,6-dimethoxyphenol in an inert gas atmosphere, adding dibutyl tin dilaurate, stirring, heating, and reacting to obtain modified steric phenol; mixing N,N-dimethylformamide, the modified steric phenol and di-tert-butyl chloromethyl phosphate, adding triethylamine, heating to reflux, stopping the reaction, washing, and drying to obtain a modified antioxidant; the plant oil-containing insulating oil prepared by the application has environmental protection, antioxidation and certain flame retardation, and is not prone to solidification at low temperature, these characteristics expand the application range of the insulating oil, and meet more strict application requirements.

This invention discloses a near-infrared photocatalytic coupling method for 2-benzene-1,2,3,4-tetrahydroisoquinoline compounds with nucleophiles. The method uses (MV)Bi₂I₈ type perovskite as a catalyst, wherein the organic portion of the catalyst, MV… 2+ The product is a methyl viologen cation. 2-Benzene-1,2,3,4-tetrahydroisoquinoline compounds are reacted with nucleophiles (dimethyl malonate, nitromethane, ethyl nitrosyl acetate) under light irradiation at room temperature or in air to undergo cross-dehydrogenation coupling reactions to obtain the corresponding product. This invention is simple to operate, operates under mild conditions, and uses readily available catalysts. It successfully achieves cross-dehydrogenation coupling between substrates using only near-infrared light, and yields high product yields.

The invention discloses insulating oil containing vegetable oil as well as a preparation method and application thereof, belongs to the technical field of lubricating oil, and aims at solving the problems that vegetable oil type insulating oil in the prior art is easy to solidify at low temperature, and the anti-oxidation stability and the flame retardance need to be further improved. The preparation method of the insulating oil containing the vegetable oil comprises the following steps: uniformly mixing dimethyl 2-(4-aminophenyl) malonate and 4-(1-ethoxyl)-2, 6-dimethoxyphenol in an inert gas atmosphere, adding dibutyltin dilaurate, stirring, heating and reacting to obtain modified sterically hindered phenol; mixing N, N-dimethylformamide, the modified sterically hindered phenol and di-tert-butyl chloromethyl phosphate, adding triethylamine, carrying out heating reflux, and after the reaction is finished, washing and drying to obtain a modified antioxidant; the vegetable oil-containing insulating oil prepared by the invention has environmental protection property, oxidation resistance and certain flame retardancy, and is not easy to solidify at low temperature, so that the application range of the insulating oil is expanded, and stricter application requirements are met.

The present invention relates to an intermediate of a pyrazole herbicide and a preparation method thereof. Compound (1) reacts with dimethyl malonate to synthesize compound (2), and compound (2) undergoes cyclization under alkaline conditions to synthesize compound (3). The present invention provides a simple, safe, environmentally friendly, high-conversion-rate and low-cost synthesis method.

Disclosed in the present invention is a process for preparing a key intermediate of fluopyram. The key intermediate is dimethyl [3-chloro-5-(trifluoromethyl)pyridin-2-yl]({[2-(trifluoromethyl)benzoyl]amino}methyl)malonate. The process comprises the following steps: in the presence of a solvent 1, reacting the compound potassium dimethyl 2-[3-chloro-5-(trifluoromethyl)pyridyl]malonate with the compound 1-D in a reaction container, and recovering the solvent 1 by means of distillation, so as to obtain the intermediate compound, wherein the solvent 1 is selected from acetic ester solvents having a boiling point range of 40-110°C at a normal temperature and a normal pressure. The process of the present invention is simple and convenient, the total yield is high, the solvent is easy to recover, and the product purity is high; the intermediate does not require any post-purification treatment, and can be directly used for the synthesis of fluopyram; and the process can be amplified, and is beneficial for cost reduction, efficiency improvement and commercial mass production.

The invention belongs to the technical field of separation of drug intermediates, and particularly relates to recovery and application of 2-methyl-2-propylmalonic acid. The method comprises the following steps: adding a polar solvent into a dipropylmalonic acid crude product prepared by a dimethyl malonate method, heating, pulping for a certain time, cooling, filtering and drying to obtain high-purity dipropylmalonic acid; and distilling the filtrate to recover the polar solvent to obtain the 2-methyl-2-propylmalonic acid as shown in the formula I. The HPLC (High Performance Liquid Chromatography) of the 2-methyl-2-propylmalonic acid is greater than 99.0% (Figure 1). The 2-methyl-2-propylmalonic acid is an intermediate for preparing the spices, namely the 2-methylpentanoic acid; and carrying out decarboxylation on the 2-methyl-2-propyl malonic acid to obtain the 2-methylvaleric acid.

The present invention relates to an improved process for the preparation of Ensifentrine of Formula-I. which comprises: reacting of 1-(3,4-dimethoxyphenethyl)urea compound of Formula II with dimethylmalonate of Formula III to obtain 1-(3,4-dimethoxyphenethyl)pyrimidine-2,4,6(1H,3H,5H)-trione of Formula IV; chlorination of compound of Formula-IV to obtain 2-chloro-9,10-dimethoxy-6,7- dihydro-4H-pyrimido[6,1-a]isoquinolin-4-one of Formula V; reacting of compound of Formula V with 2,4,6-trimethyl aniline of Formula VI to obtain (E)-2-(mesitylimino)-9,10- dimethoxy-2,3,6,7-tetrahydro-4H-pyrimido[6,1-a]isoquinolin-4-one compound of Formula VII; condensation of compound of Formula VII with compound of Formula VIII or a compound of Formula IX or a salt thereof to obtain (E)-1-(2-(2-(mesitylimino)-9,10- dimethoxy-4-oxo-6,7-dihydro-2H-pyrimido[6,1-a] isoquinolin-3(4H)-yl)ethyl)urea (Ensifentrine) of Formula I; optionally converting the compound of Formula I to its pharmaceutically acceptable salts thereof. The invention further comprises purification of crude Ensifentrine by reacting with salt forming agent in a suitable solvent followed by treating with a suitable base and a suitable solvent to obtain pure Ensifentrine freebase of Formula I.

The present application relates to the technical field of delta-lactone synthesis, in particular to a high-purity delta-lactone synthesis method, comprising the following steps: using potassium carbonate to catalyze Michael addition reaction of the active methylene functional group of dimethyl malonate and the alpha, beta-alkenyl functional group of 1-octene-3-ketone to generate intermediate product I; intermediate product I generates decarboxylation reaction under the catalysis of boric acid to generate intermediate product II; chiral ligand supported nickel catalyst catalyzes asymmetric hydrogenation reaction of the delta-carbonyl functional group of intermediate product II to generate chiral delta-hydroxyl functional group, and ester exchange reaction of the chiral delta-hydroxyl functional group and the ester functional group of intermediate product II to generate chiral delta-decalactone. The present application designs and synthesizes four chiral ligand supported nickel catalysts on one hand, and designs a new route capable of synthesizing chiral delta-decalactone with high optical purity on the other hand.

The present application belongs to the field of chemical synthesis and pesticides, and particularly relates to a preparation method of an enoxacin intermediate 5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-ketone. The present application comprises: using 3-ethylthiobutyraldehyde and methyl acetoacetate as raw materials, generating 2-acetyl-5-(ethylthio)hex-2-enate acid methyl ester through a Brain-Von Eggers reaction, then performing Michael addition and Claisen ester condensation with dimethyl malonate, and then performing hydrolysis through sodium hydroxide, and heating decarboxylation through hydrochloric acid to obtain 5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-ketone. The preparation method is simple, convenient to operate, and easy to be scaled up in industry, and finally, the total yield of the similar one-pot reaction is as high as 77%.

The invention relates to a preparation method of a clethodim intermediate, which comprises the following steps: carrying out addition reaction on dimethyl malonate and 6-ethylthio-3-heptene-2-ketone in the presence of a catalytic amount of dimethyl malonate sodium salt to generate an intermediate compound shown as a formula (3), # imgabs0 #

The application relates to the technical field of biodegradable polyesters, and provides a modified polybutylene terephthalate-co-adipate and a preparation method thereof. The repeating structural unit of the modified polybutylene terephthalate-co-adipate comprises a terephthalic acid structural unit, an adipic acid structural unit, a 1,4-butanediol structural unit and a fourth monomer structural unit; the fourth monomer comprises at least one of oxalic acid, dimethyl oxalate, furan dicarboxylic acid, dimethyl furan dicarboxylic acid, malonic acid, dimethyl malonic acid, methylmalonic acid and diethyl methylmalonic acid. The modified polybutylene terephthalate-co-adipate provided by the application has higher glass transition temperature and breaking strength, lower melt index and better product hue than conventional pure PBAT, can meet the use requirements of PBAT, and effectively solves various problems caused by poor heat resistance and strength of conventional PBAT products in the processing process and subsequent application.

The invention provides a synthetic method of methyl cyclopentyl formate, and relates to the technical field of synthesis of organic chemical intermediates. The synthesis of the cyclopentyl methyl formate comprises the following steps: carrying out substitution cyclization reaction on 1, 4-dihalogenated butane serving as an initial raw material and dimethyl malonate to obtain 1, 1-cyclopentyl dimethyl dicarboxylate, and carrying out Krapcho degreasing reaction on the 1, 1-cyclopentyl dimethyl dicarboxylate to obtain a target compound, namely the cyclopentyl methyl formate. The method overcomes the defects in the prior art, is simple in synthesis route, low in raw material cost and easy to obtain, is suitable for industrial production, and provides a new synthesis scheme for synthesis and preparation of methyl cyclopentyl formate.

The invention relates to a preparation method of magnesium valproate as shown in a chemical structural formula I. The preparation method comprises the following steps: carrying out dipropylation on dimethyl malonate and 1-chloropropane in a DMF (Dimethyl Formalonate) solvent under the action of potassium carbonate and PTC (Positive Temperature Coefficient) to prepare dimethyl dipropyl malonate as shown in a formula III; carrying out hydrolysis reaction on the dipropyl malonic acid III to prepare dipropyl malonic acid as shown in a formula II; uniformly mixing II with magnesium oxide, heating and decarboxylating to prepare magnesium valproate as shown in the formula I, wherein the total yield of magnesium valproate is not less than 90.0%; the preparation reaction is as follows: # imgabs0 #, the PTC of dipropylation is selected from quaternary ammonium salt, the reaction temperature is 50-140 DEG C, and the reaction time is 4.0-14.0 h; the hydrolysis temperature is 70-95 DEG C, and the hydrolysis time is 2.0-4.0 h; the decarboxylation temperature is 140-158 DEG C, and the decarboxylation time is 3.0-5.0 hours.

The invention discloses a method for synthesizing a pimobendan intermediate, comprising the following steps: Step 1: Compound I and Compound A undergo a Friedel-Crafts acylation reaction in an aprotic solvent under the action of a Lewis acid to generate Compound II; Step 2: Using ether as a solvent and under alkaline conditions, Compound II undergoes a substitution reaction with dimethyl malonate or diethyl malonate, and the resulting compound undergoes a hydrolysis reaction in an alkaline aqueous solution to generate Compound III; Step 3: Compound III is heated under the conditions of hydrazine hydrate and an acid to generate Compound IV, i.e., the pimobendan intermediate. This synthetic method eliminates the nitration reaction step, which is highly dangerous and produces a large amount of waste acid water, and has a short route and simple operation.