75 results about "Claisen rearrangement" patented technology

The invention belongs to the field of chemical synthesis, in particular relates to a synthesis method of a natural product mangostin which is shown in the formula (I) and has good anti-tumor activity, anti-inflammation activity and anti-bacterial activity. The method provided by the invention comprises the following steps of: taking 2,4,5-trialkoxy benzoic acid and 1,3,5-trialkoxy benzene as initial raw materials; carrying out acyl chlorination, Friedel-Crafts acylation and cyclization to prepare a key intermediate 1,3,6,7-tetraalkoxy xanthone; and then, carrying out dealkylation, allylation, Claisen rearrangement, methylation, oxidation reaction, WITTING reaction and dealkylation reaction so as to prepare the mangostin.

The invention discloses a thermosetting resin combination and a preparation method of the thermosetting resin combination. The thermosetting resin combination is prepared by prepolymerization reaction between Claisen rearrangement allylated novolac resins whose weight percentage is of 66 to 90 percent and bismaleimide monomers whose weight percentage is of 10 to 34 percents in the temperature of 100 to 150 DEG C. The Claisen rearrangement allyl novolac resin is made through a Claisen rearrangement reaction of allyl etherified novolac resins. The bismaleimide monomers are provided with a formula I structure, wherein, R1 and R2 are H; R is (see above graph). The invention is not only in high glass transition temperature, but also in fine resistance to heat deterioration performance. Fiber reinforced composites of the invention has high temperature strength/modulus retention, which can be used for preparing high temperature resistant composites that is used temporarily under the temperature of 350 DEG C, and can be applied widely in manufacturing the high temperature resistant composites such as matrix resins for missile radomes in aerospace industry.

Disclosed are an epoxy compound having an alkoxysilyl group, a composite of which exhibits good heat resistant properties and/or a cured product of which exhibits good flame retardant properties, a method of preparing the same, a composition comprising the same, and a cured product and a use of the composition. An alkoxysilylated epoxy compound comprising at least one of Chemical Formula S1 substituent and at least two epoxy groups in a core, a method of preparing the epoxy compound by an allylation, a claisen rearrangement, an epoxidation and an alkoxysilylation, an epoxy composition comprising the epoxy compound, and a cured product and a use of the composition are provided. The composite of the disclosed exhibits improved chemical bonding, good heat resistant properties, a low CTE, a high glass transition temperature or Tg-less The cured product of the composition exhibits good flame retardant properties.

The invention provides a method for preparation of citral. The method comprises that cis/trans-isopentenyl-3-methyl butadiene ether is subjected to Claisen rearrangement to form 2, 4, 4-trimethyl-3-formyl-1, 5-hexadiene, and the 2, 4, 4-trimethyl-3-formyl-1, 5-hexadiene is subjected to Cope rearrangement to form citral (3, 7-dimethyl-2, 6-octadien-1-aldehyde). The method utilizes an ester as a side reaction inhibitor to adjust a reaction rate. The method has high selectivity, a fast reaction rate and whole process residence time of 1-15min.

The invention provides a preparation method of citral. The method comprises the following steps: in a supercritical condition, carrying out thermal cracking reaction on one or more of isoprenaldehydediisobutenol, isoprenaldehyde diisopentenol and isoprenaldehyde diisopentenol as raw materials to obtain cis/trans-isopentenyl-3-methyl-butadiene; and carrying out Claisen rearrangement and Cope rearrangement on the cis/trans-isopentenyl-3-methyl-butadiene to obtain the citral. The method provided by the invention is characterized in that the thermal cracking process is carried out in the supercritical condition, the cis/trans-isopentenyl-3-methyl-butadiene is separated in a flash manner, and a trialkyl aluminum catalyst is introduced in a flash tank to direct rearrange the cis/trans-isopentenyl-3-methyl-butadiene in the flash process to obtain the citral, so that the reaction time is shortened greatly and the product yield is increased.

The invention discloses a benzenesulfonic acid catalyst supported on silica gel, which is prepared by adopting silica gel to react with thionyl chloride, phenol and chlorosulfonic acid sequentially. In the catalyst, the silica gel and benzenesulfonic acid are bonded in a covalent bond mode, so that the supporting capacity is stable, and the supporting capacity of the benzenesulfonic acid is about 2.25mmol/g in the benzenesulfonic acid catalyst supported on silica gel through analysis and calculation. Experiments prove that: the prepared catalyst has efficient catalytic activity to two kinds of atom economic reactions, namely Beckmann rearrangement reaction and Claisen rearrangement reaction, is non-toxic, harmless and noncorrosive, is easily separated, can be recycled, and accords with green and environmentally-friendly national industrial policy.

The invention discloses a method for preparing a halofuginone intermediate shown in a formula D or E. The method comprises the following steps of: (1) dropwise adding solution of a compound F into benzyl chloroformate solution, and performing Van Braun reaction to obtain a compound E; and (2) performing Claisen rearrangement reaction on the compound E obtained in the step (1). By the method, the Van Braun reaction can be completely performed, the using amount of benzyl chloroformate is reduced, the efficiency of the reaction is improved, and a 2-bit product can be selectively obtained in the subsequent Claisen rearrangement reaction. In the better embodiment of the invention, the operation process is simplified by a one-pot method, the using amount of solvents is reduced, the selectivity is improved, the cost of the reaction is reduced, the pollution to the environment is reduced, and good conditions are created for mass production of halofuginone.

The invention discloses a synthesis method of 2-substituted-3, 4-dihyidro-1-isoquinoline ketone compound and a relative application in the drug preparation for cardiovascular disease, wherein the compound is represented as above, R1 is gaseous normal alkyl and aromatic group or various substituted alkyl and aromatic group of C1-C19, R2 is OH, OCH3, CH3, NO2 and halogen or the like and can be one or more substituents. The preparation of 2-substituted-3, 4-dihyidro-1-isoquinoline ketone compound uses isovanillic acid ester as raw material, via six-step reaction as allyl etherified, Claisen rearrangement, oxidation, reaction with primary amine (generating Schiff base), reduction and aminolysis of molecular lactone, to synthesize the product. The isolated arterial ring tension test proves that the compound can relax vessel effectively. The 2-substituted-3, 4-dihyidro-1-isoquinoline ketone compound is a new potential cardiovascular drug, with wide application for preparing the drug of cardiovascular disease.

The present invention relates to two magnolol derivatives and their preparation methods. In the concrete, one is compound 5,5'-dipropenyl diphenyl diphenol and its preparation method, said preparation method is characterized by making magnolol undergo the process of isomerization reaction to obtain said compound; and another derivative is compound 3,3'diallyl-5,5'-dipropenyl diphenyl diphenol and its preparation method, said method is characterized by including the following steps: making 5,5-dipropenyl diphenyl diphenol and allyl bromide undergo the process of Williamson reaction to synthesize allyl ether, then making Claisen rearrangement so as to obtain said derivative.

The invention relates to a high-tenacity flame-retardant bismaleimide resin and a preparation method of the high-tenacity flame-retardant bismaleimide resin. The resin is composed of 100 parts of diphenylmethane bismaleimide, 1-100 parts of diallyl bisphenol A, 1-100 parts of bisphenol A diallyl ether, 1-50 parts of O,O-bis(4-(allyloxy) phenyl) phenyl phosphonic acid). Both the bisphenol A diallyl ether and the O,O-bis(4-(allyloxy) phenyl) phenyl phosphonic acid) undergo claisen rearrangement at a high temperature to be transformed into derivatives of diallyl and then participate in the curing reaction of the resin, and therefore the bisphenol A diallyl ether can effectively decrease the viscosity of a prepolymer at a low temperature and improve the forming process of the resin; phosphorus in the O,O-bis(4-(allyloxy) phenyl) phenyl phosphonic acid) can restrain combustion of the resin and make the resin generate a small amount of smoke without poisonous or corrosive gas in combustion, meets environmental requirements and has good compatibility with the resin.

The invention provides a preparation method of azithromycin amine. The preparation method is characterized by adopting a one-pot reaction method. The preparation method comprises the steps of carrying out Beckman rearrangement for erythrocin A9- oxime, water and rearrangement reagent, adjusting the pH value to be 3.0 to 7.0 after the reaction is ended, adding reducing agent to reduce the reactants, and obtaining the azithromycin amine through acid hydrolysis and crystallization. The one-pot reaction of the Beckman rearrangement and reduction is realized by adopting water as the solvent, so that the time for producing erythrocin A9- oxime or erythrocin A9-oxime thiocyanate and the azithromycin amine can be greatly shortened, the procedures can be reduced, the emission of waste gas, waste water and industrial residue can be reduced, the yield is improved by 1 to 3 percent compared with the original process, and the production cost of the azithromycin is further reduced. The midbody erythrocin A6, 9 imino ether is not extracted, and the reaction condition is moderate; the water is used as the reaction solvent, less waste (waste water, waste gas and industrial residue) is produced, and the environmental friendliness can be realized.

The invention provides a synthetic method for methyl caulophine. The method comprises the following steps: with isovanillin and p-hydroxyanisole as raw materials, successively subjecting isovanillin to bromination and methylation so as to obtain 2-bromo-3,4- dimethoxy benzaldehyde; successively subjecting p-hydroxyanisole to acetylation, bromination, hydrolyzation, allyl etherification, Claisen rearrangement and methylation so as to obtain 1-allyl-4-bromo-2,5-dimethoxybenzene; successively subjecting the obtained 1-allyl-4-bromo-2,5-dimethoxybenzene and 2-bromo-3,4- dimethoxy benzaldehyde to Grignard reaction, ruthenium chloride/sodium periodate double-bond oxidation, reductive amination, pyridine chlorodichromate oxidation and intramolecular coupling so as to obtain 3-(2-(N,N-dimethylamino)methyl)-1,4,5,6-tetramethoxyl-9-H-fluorene-9-ketone, i.e. the method for synthesizing methyl caulophine is completed. The method in the invention has the advantages of mild reaction conditions, simple operation, easily-available raw materials and reagents, etc., and is suitable for large-scale production of pharmaceutical enterprises

The invention provides a method for synthesizing 1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-ketone. The method comprises the following steps: a, performing the Claisen rearrangement reaction of a compound III in an appropriate solvent to generate a compound IV; b. supplying ozone to the compound IV at a low temperature to perform reaction, adding sodium borohydride or potassium borohydride to perform reduction reaction and obtaining a compound V; c, allowing the compound V to react with methanesulfonyl chloride or p-toluenesulfonyl chloride in pyridine so as to obtain a compound VI and a compound VII; and d, dissolving the compound VI and/or the compound VII in an appropriate reaction solvent, adding appropriate organic base, raising temperature to perform reaction, cooling the obtained product, adding diluted hydrochloric acid for washing, evaporating the solvent and obtaining a compound I, namely the 1,2,6,7-tetrahydro-8H-indeno[5,4-b]furan-8-ketone. The method has the advantages ofbrief synthesis route, simple operation, low cost, high yield and convenience for industrial production.

The invention discloses a preparation method and application of allyloxy-containing aromatic polyimide. The allyloxy-containing high polymer compound has a repeated structure unit of a formula I shownin the description. According to the preparation method, a diallyloxy diamine monomer is selected as a basic monomer, the basic monomer is copolycondensed with binary aromatic primary amine and quaternary anhydride according to a ratio, and thus a series of novel aromatic polyimide of different contents of allyloxy is prepared. Hydroxyl and allyl can be obtained from a prepared allyloxy-modifiedpolyimide film through claisen rearrangement. Due to the hydroxyl, the separation selectivity of the film upon gases can be improved, and the allyl can be used as a crosslinking reaction site to improve the plastification resistance of the film. Due to the novel molecular structure designing, a new generation of gas separation films with both separation and plastification resistance can be prepared.

The invention is a method to synthesize (S)-(-)-N-[(1-allyl-2-pyrrolidyl)methyl]-2,3-dimethoxy-5 -(3-hydroxy propyl)benzoic amide, relating to a technique to prepare PET developer. It adopts (S)-(-)-2-formamidopyrrol through allylation and electronation reaction to make (S)-(-)-2- methylamino-N-(allyl)pyrrol alkyl (3); adopts 2-hydroxy-3-methoxy methyl benzoate through allylation, Claisen rearrangement, hydroboration and hydrolyzation reaction to make 2,3-dimethoxy-5-(3-hydroxy propyl)benzoic acid (8); (3) and (8) react to make the aim compound. It improves the synthesis method reported in document, replacing expensive allyl iodide with allyl bromide to make the compound (3). It improves the purifying condition of intermediate.

A novel Rh(I)-catalyzed approach to synthesizing functionalized (E,Z) dienal compounds has been developed via tandem transformation where a stereoselective hydrogen transfer follows a propargyl Claisen rearrangement. Z-Stereochemistry of the first double bond suggests the involvement of a six-membered cyclic intermediate whereas the E-stereochemistry of the second double bond stems from the subsequent protodemetallation step giving an (E,Z)-dienal. The reaction may be represented by the following sequence.

The invention provides a method for catalyzing Claisen rearrangement at a relatively low temperature, and relates to the field of catalysis, and the method uses a catalyst DAPs to catalyze allyl ether of enol to obtain a Claisen rearrangement product through rearrangement. According to the reaction, the production energy consumption can be reduced, the operation can be simplified, and meanwhile the requirement for equipment is low.

The present invention relates to synthesis process of 4-(1, 5-dimethyl-1-vinyl-4-hexenyl) phenol, normally named as antifeedant, and the synthesis process is superior to available ones. The synthesis process has geraniol as main material and includes the reaction with vinyl ethyl ether, Claisen rearrangement reaction to obtain 3-vinyl-rhodinal, reaction with hexahydropyridine, enamiation, conjugate addition with methyl vinyl ketone and cyclization and condensation to 4-(1, 5-dimethyl-1-vinyl-4-hexenyl)-2-cyclohexene ketone, and dehydrogenation to obtain the product 4-(1, 5-dimethyl-1-vinyl-4-hexenyl) phenol. The present invention uses natural product as main material, and has simple reaction process, high selectivity and high yield.

The invention discloses a synthetic method of 7-(4-ethyl-1-methyl octyl)-8-hydroxyquinoline. The method is characterized by comprising the following steps of: undergoing a Williamson synthetic reaction on 8-hydroxyquinoline and alkenyl halide in a solvent under the catalytic action of an alkali to generate 8-[4-(5-ethyl-2-nonylene)]oxyquinoline, performing Claisen rearrangement on ether allyl phenyl at a reaction temperature, and performing intramolecular rearrangement on ether allyl phenyl to generate 7-(4-ethyl-1-methyl octenyl)-8-hydroxyquinoline, wherein the alkenyl halide is selected from 3-chloro-5-ethyl-2-nonylene, 3-bromo-5-ethyl-2-nonylene and 3-iodine-5-ethyl-2-nonylene; and hydrogenating the 7-(4-ethyl-1-methyl octenyl)-8-hydroxyquinoline under the catalytic action of palladium/carbon to obtain a final product, i.e., 7-(4-ethyl-1-methyl octyl)-8-hydroxyquinoline. The method has the advantages of high product yield, high quality and suitability for industrial production.