- A regioselective tsuji-trost pentadienylation of 3-allyltetronic acid
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A regioselective Tsuji-Trost reaction of sodium 3-allyltetronate with methyl 5-trimethylsilylpenta-2,4-dienyl carbonate was developed. Carbon-carbon bond formation at the more highly substituted terminus of the pentadienyl residue was possible by introduc
- Schobert, Rainer,Barnickel, Bertram
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- Synthesis and pH-dependent hydrolysis profiles of mono- and dialkyl substituted maleamic acids
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Maleamic acid derivatives as weakly acid-sensitive linkers or caging groups have been used widely in smart delivery systems. Here we report on the controlled synthetic methods to mono- and dialkyl substituted maleamic acids and their pH-dependent hydrolysis behaviors. Firstly, we studied the reaction between n-butylamine and citraconic anhydride, and found that the ratio of the two n-butyl citraconamic acid isomers (α and β) could be finely tuned by controlling the reaction temperature and time. Secondly, we investigated the effects of solvent, basic catalyst, and temperature on the reaction of n-butylamine with 2,3-dimethylmaleic anhydride, and optimized the reaction conditions to efficiently synthesize the dimethylmaleamic acids. Finally, we compared the pH-dependent hydrolysis profiles of four OEG-NH2 derived water-soluble maleamic acid derivatives. The results reveal that the number, structure, and position of the substituents on the cis-double bond exhibit a significant effect on the pH-related hydrolysis kinetics and selectivity of the maleamic acid derivatives. Interestingly, for the mono-substituted citraconamic acids (α-/β-isomer), we found that their hydrolyses are accompanied by the isomerization between the two isomers.
- Su, Shan,Du, Fu-Sheng,Li, Zi-Chen
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supporting information
p. 8384 - 8392
(2017/10/19)
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- Preparation method of 2-methyl-3-ethyl maleic amide
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The invention relates to a preparation method of 2-methyl-3-ethyl maleic amide. The method comprises the following steps: preparing dimethyl maleic anhydride; preparing 2-methyl-3-ethyl maleic anhydride; and preparing 2-methyl-3-ethyl maleic amide. A process route develops a synthetic method of a series of maleimide and maleic anhydride, and meanwhile, a flavoring application experiment is performed on the series of precursor-aroma compounds, thereby providing an important support for developing novel perfume materials.
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Paragraph 0073-0074; 0085-0086; 0097-0098; 0109-0110; 0121
(2017/08/29)
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- Preparation of the maleic anhydride nucleus from dichloro γ-lactams: Focus on the role of the N-substituent in the functional rearrangement and in the hydrolytic steps
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The preparation of the 3,4-dialkyl-substituted maleic anhydride nucleus, through the functional rearrangement of dichloro γ-lactams, allowed the comparison of various N-substituents in the functional rearrangement step. The 2-pyridyl group proved to be the most appropriate N-substituent for the hydrolysis of the 5-methoxy-1,5-dihydro-2H-pyrrol-2-one intermediate into the 5-hydroxy adduct, and for the hydrolysis of the maleimide nucleus into the maleic anhydride. The oxidation of the 5-hydroxy-1,5-dihydro-2H-pyrrol-2-one into the corresponding maleimide was achieved with manganese(IV) oxide. Georg Thieme Verlag Stuttgart.
- Ghelfi, Franco,Pattarozzi, Mariella,Roncaglia, Fabrizio,Parsons, Andrew F.,Felluga, Fulvia,Pagnoni, Ugo M.,Valentin, Ennio,Mucci, Adele,Bellesia, Franco
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experimental part
p. 3131 - 3141
(2009/04/06)
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- A short approach to chaetomellic anhydride A from 2,2-dichloropalmitic acid: Elucidation of the mechanism governing the functional rearrangement of the chlorinated pyrrolidin-2-one intermediate
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Chaetomellic anhydride A was efficiently attained in three steps, starting from 2,2-dichloropalmitic acid and 2-(3-chloro-2-propenylamino)pyridine. Atom transfer radical cyclisation selectively formed the cis-stereoisomer of the trichloropyrrolidin-2-one, which underwent a stereospecific functional rearrangement to form a substituted maleimide. The choice of 2-pyridyl, as 'cyclisation auxiliary' in the atom transfer radical cyclisation step, proved beneficial for hydrolysis of the maleimide to form the desired anhydride.
- Bellesia, Franco,Danieli, Chiara,Buyck, Laurent De,Galeazzi, Roberta,Ghelfi, Franco,Mucci, Adele,Orena, Mario,Pagnoni, Ugo M.,Parsons, Andrew F.,Roncaglia, Fabrizio
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p. 746 - 757
(2007/10/03)
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- An efficient synthesis of dimethylmaleic anhydride
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A facile three-step synthesis of dimethylmaleic anhydride (8) with 74% overall yield has been described starting from maleimide 1, via methylmaleimide 4, using two Wittig reactions followed by an alkaline hydrolysis.
- Mangaleswaran, Sivaprakasam,Argade, Narshinha P.
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p. 865 - 868
(2007/10/03)
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- Vapor-phase oxidation and oxidative ammonolysis of some methyl derivatives of biphenyl
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Main pathways arc established of catalytic oxidative transformations of 3,4-di- and 3,3',4,4'-tetramethylbiphenyls in vapor phase. The possibility is analyzed of obtaining the corresponding anhydrides, imides, and nitriles of biphenylcarboxylic acids in yields of up to 59-69%.
- Shapovalov,Koshel',Sembaev,Postnova,Koshel'
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p. 1386 - 1390
(2007/10/03)
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- Dicarboxylic Acids Link Proton Transfer Across a Liquid Membrane to the Synthesis of Acyl Phosphates. A Model for P-Type H(+)-ATPases
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H(+)-ATPases are ion pumps that link proton transfer across cell membranes to the synthesis or hydrolysis of ATP.A current research goal is to understand the molecular-level mechanism of this linking.We present a chemical model that mimics some features of H(+)-ATPases by linking proton transfer across a liquid membrane to the synthesis of acyl phosphates using carboxylic acid anhydride intermediates.Citraconic acid (cis-2-methyl-2-butenedioic acid) accelerated the transfer of protons from a pH 0.3 solution across a chloroform liquid membrane to a pH 10 solution.The mechanism involved spontaneous formation of a small amount of citraconic anhydride (0.6percent) in the pH 0.3 layer.This anhydride partitioned into the chloroform layer and diffused to the pH 10 layer, where it hydrolyzed, generating two protons.When the pH 10 layer contained phosphate (1.0 M), some of the citraconic anhydride reacted with phosphate to form citraconyl phosphate, 5.0percent yield.In separate experiments, we confirmed that citraconyl phosphate had high phosphoryl donor potential by reacting it with morpholine to form a phosphoramidate (11.5percent yield) or with fluoride to form fluorophosphonate (32percent yield).To demonstrate the link between an acyl phosphate and a proton gradient in the reverse direction, we used succinyl phosphate, whose hydrolysis occurs in two steps: formation of succinic anhydride, which consumes protons, followed by hydrolysis of succinic anhydride, which releases protons.We generated a pH gradient by carrying out these two steps in separate solutions.Hydrolysis of succinyl phosphate (3.9 mmol) at pH 6.00 started with a increase in pH to 6.16 (0.59 mmol of H(+) consumed) caused by the formation of succinic anhydride.We extracted this anhydride with dichloromethane and transferred it to a separate solution at pH 6.05.Hydrolysis of the anhydride released protons (0.36 mmol), decreasing the pH to 5.23.Our model suggests that H(+)-ATPases could use acyl phosphates and carboxylic acid anhydride intermediates to link proton transfer to ATP synthesis or hydrolysis.
- Colton, Ian J.,Kazlauskas, Romas J.
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p. 3626 - 3635
(2007/10/02)
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- Process for the preparation of dimethylmaleic anhydride
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The reaction of maleic acid, fumaric acid and/or maleic anhydride at elevated temperature and in the presence of catalytic amounts of a heterocyclic amidine or a salt thereof with protonic acids affords dimethylmaleic anhydride in good yield.
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- Process for the preparation of dimethylmaleic anhydride
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The reaction of maleic acid, fumaric acid and/or maleic anhydride in the presence of N-acylated heterocyclic amidines and at elevated temperature affords dimethylmaleic anhydride in good yield. Catalytic amounts of the amidine employed are sufficient for said reaction.
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- SOME REACTIONS OF PHENOLIC MALEAMIC ACIDS RELEVANT TO CARBOXYPEPTIDASE CATALYSIS
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In neutral aqueous acetonitrile, N-o-hydroxybenzyl-2,3-dimethylmaleamic acid is rapidly converted to N-o-hydroxybenzyl-2,3-dimethylmaleimide, while N-propyl-N-o-hydroxybenzyl-2,3-dimethylmaleamic acid is converted to dimethylmaleic anhydride; both reactions are catalyzed by the phenolic groups.
- Chin, Jik,Breslow, Ronald
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p. 4221 - 4224
(2007/10/02)
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- Dianions Derived from α-Halo Acids. The Darzens Condensation Revisited
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The dianions of α-halo carboxylic acids are readily generated by the addition of the acids to 2 equiv of lithium diisopropylamide at low temperatures.When the mixture warms to room temperature dimeric products are formed.When aldehydes and ketones were added to the cooled solutions of the dianions and the reaction mixtures were allowed to warm to room temperature, followed by acid quench, glycidic acids were formed.The glycidic acids, per se, were often too unstable to be isolated and purified but could be analyzed by conversion to their methyl esters withdiazomethane.When the reactions were quenched prematurely, α-chloro-β-hydroxy carboxylic acids were isolated.Homologated aldehydes and ketones were obtained from the glycidic acids by catalytic and thermal decarboxylation methods.
- Johnson, Carl R.,Bade, Thomas R.
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p. 1205 - 1212
(2007/10/02)
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