Journal articles: 'Esters – Synthesis'

1

Janin, Yves, Vincent Hervin, Eloi Coutant, and Glwadys Gagnot. "Synthesis of α-Amino Esters via α-Nitro or α-Oxime Esters: A Review." Synthesis 49, no. 18 (August 9, 2017): 4093–110. http://dx.doi.org/10.1055/s-0036-1589506.

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This review is an in-depth survey of the reported synthetic approaches for the preparation of racemic α-amino esters via the reduction of α-nitro or α-oxime ester intermediates. Accordingly, it describes the many pathways that have been designed to prepare such intermediates. This includes synthesis starting with α-nitroacetates, dialkyl malonates, acetoacetates, diethyl oxalates as well as [2+3] or [2+4] cycloadditions using, respectively, alkyl carbonocyanidate N-oxides or alkyl 2-nitrosoacrylates. This review also contains the description of a myriad of side reactions which can occur when working with α-nitro esters.1 Introduction2 α-Amino Esters from α-Nitroacetates via Condensation Reactions3 α-Amino Esters via C-Alkylation or C-Arylation of α-Nitroacetates4 α-Amino Esters from α-Nitroacetates Using Other Reactions5 Synthesis of α-Amino Esters via α-Oxime Esters6 Synthesis of α-Amino Esters via [2+3] Cycloadditions7 Synthesis of α-Amino Esters via [2+4] Cycloadditions8 On the Reduction of α-Oxime Esters9 Conclusion

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Bardi, Laura, Cristina Crivelli, and Mario Marzona. "Esterase activity and release of ethyl esters of medium-chain fatty acids by Saccharomyces cerevisiae during anaerobic growth." Canadian Journal of Microbiology 44, no. 12 (December 1, 1998): 1171–76. http://dx.doi.org/10.1139/w98-124.

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During anaerobic fermentation, Saccharomyces cerevisiae releases large amounts of medium-chain fatty acids (MCFAs) and related ethyl esters which are very important for aromatic quality of fermented beverages. The physiological function of ester synthesis is not yet understood. As MCFAs are toxic, their conversion to esters has been proposed to be a detoxification mechanism. Esterases possess ester synthesizing ability. Throughout an anaerobic fermentation of a lipid-free synthetic medium carried out with a S. cerevisiae strain selected for wine making, we have monitored MCFA and ethyl ester production and, at the same time, measured growth and esterasic activity of intact cells. Because no correlation was found between the concentration of each fatty acid and its ethyl ester, there is no evidence that ester synthesis reduces the toxicity of MCFAs. Esterasic activity did not show any correlation with ester synthesis, but it was related to the release of MCFAs. A model is proposed in which ester synthesis is a consequence of the arrest of lipid biosynthesis resulting from a lack of oxygen. Under these conditions, an excess of acyl coenzyme A is produced, and acyl esters are formed as secondary products of reactions aimed at recovering free coenzyme A.Key words: yeast, esterase, medium-chain fatty acids, toxicity, ethyl esters.

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Aizouq, Mohammed, Helga Peisker, Katharina Gutbrod, Michael Melzer, Georg Hölzl, and Peter Dörmann. "Triacylglycerol and phytyl ester synthesis inSynechocystissp. PCC6803." Proceedings of the National Academy of Sciences 117, no. 11 (March 2, 2020): 6216–22. http://dx.doi.org/10.1073/pnas.1915930117.

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Cyanobacteria are unicellular prokaryotic algae that perform oxygenic photosynthesis, similar to plants. The cells harbor thylakoid membranes composed of lipids related to those of chloroplasts in plants to accommodate the complexes of photosynthesis. The occurrence of storage lipids, including triacylglycerol or wax esters, which are found in plants, animals, and some bacteria, nevertheless remained unclear in cyanobacteria. We show here that the cyanobacteriumSynechocystissp. PCC6803 accumulates both triacylglycerol and wax esters (fatty acid phytyl esters). Phytyl esters accumulate in higher levels under abiotic stress conditions. The analysis of an insertional mutant revealed that the acyltransferase slr2103, with sequence similarity to plant esterase/lipase/thioesterase (ELT) proteins, is essential for triacylglycerol and phytyl ester synthesis inSynechocystis. The recombinant slr2103 enzyme showed acyltransferase activity with phytol and diacylglycerol, thus producing phytyl esters and triacylglycerol. Acyl-CoA thioesters were the preferred acyl donors, while acyl-ACP (acyl carrier protein), free fatty acids, or galactolipid-bound fatty acids were poor substrates. The slr2103 protein sequence is unrelated to acyltransferases from bacteria (AtfA) or plants (DGAT1, DGAT2, PDAT), and therefore establishes an independent group of bacterial acyltransferases involved in triacylglycerol and wax ester synthesis. The identification of the geneslr2103responsible for triacylglycerol synthesis in cyanobacteria opens the possibility of using prokaryotic photosynthetic cells in biotechnological applications.

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Ramapanicker, Ramesh, Rohit Gupta, Rajendran Megha, and Srinivasan Chandrasekaran. "Applications of Propargyl Esters of Amino Acids in Solution-Phase Peptide Synthesis." International Journal of Peptides 2011 (June 16, 2011): 1–10. http://dx.doi.org/10.1155/2011/854952.

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Propargyl esters are employed as effective protecting groups for the carboxyl group during solution-phase peptide synthesis. The propargyl ester groups can be introduced onto free amino acids by treating them with propargyl alcohol saturated with HCl. The reaction between propargyl groups and tetrathiomolybdate is exploited to deblock the propargyl esters. The removal of the propargyl group with the neutral reagent tetrathiomolybdate ensures that most of the other protecting groups used in peptide synthesis are untouched. Both acid labile and base labile protecting groups can be removed in the presence of a propargyl ester. Amino acids protected as propargyl esters are employed to synthesize di- to tetrapeptides in solution-phase demonstrating the possible synthetic utilities of the methodology. The methodology described here could be a valuable addition to currently available strategies for peptide synthesis.

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Nguyen, Trang, Hung Mac, and Phong Pham. "Preparation of Key Intermediates for the Syntheses of Coenzyme Q10 and Derivatives by Cross-Metathesis Reactions." Molecules 25, no. 3 (January 21, 2020): 448. http://dx.doi.org/10.3390/molecules25030448.

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An alternative catalytic strategy for the preparation of benzylmethacrylate esters, key intermediates in the synthesis of coenzyme Q10 and derivatives, was reported. This strategy avoided undesirable stoichiometric reduction/oxidation processes by utilizing the catalytic formation of allylarenes and then cross-metathesis to selectively form E-benzylmethacrylate esters with good yields (58–64%) and complete E-selectivity. The ester intermediates were reduced to common key benzylallylic alcohols (90–92% yield), which were subsequently used in the formal syntheses of coenzyme Q10 and one derivative.

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Zhou, Yongyun, Ruhima Khan, Baomin Fan, and Lijin Xu. "Ruthenium-Catalyzed Selective Reduction of Carboxylic Esters and Carboxamides." Synthesis 51, no. 12 (April 30, 2019): 2491–505. http://dx.doi.org/10.1055/s-0037-1611524.

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Amines and alcohols are important classes of building blocks in organic synthesis. The synthesis of these compounds has been a topic of interest. A straightforward method for their synthesis is the reduction of esters and amides to alcohols and amines, respectively. Various transition-metal catalysts have been developed for the homogeneous hydrogenation of esters and amides to alcohols and amines. In this review, an overview of the ruthenium-catalyzed selective hydrogenation of esters and amides is provided.1 General Introduction2 Ru-Catalyzed Reduction of Esters3 Ru-Catalyzed Selective Reduction of Amides4 Conclusions

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Santoso, Aman, Abdurrohman, Anugrah Ricky Wijaya, Dedek Sukarianingsih, Sumari, and Daratu Eviana Kusuma Putri. "Synthesis of Methyl Ester from Rice Bran Oil through the Esterification Reaction." Key Engineering Materials 851 (July 2020): 164–71. http://dx.doi.org/10.4028/www.scientific.net/kem.851.164.

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Vegetable oil is one of rice bran components. As triglycerides, vegetable oil can be converted to fatty acid and alkyl esters for further treatments. Synthesis of alkyl ester oil can be carried out by esterification or transesterification reaction, depending on the quality of the oil and the catalyst. The purposes of this study are 1) Rice bran oil isolation, 2) Oil esterification 3) Characterization and identification of the methyl ester that compose rice bran oil. The stages in this research are 1) Extraction of rice bran oil, 2) Synthesis of methyl ester from rice bran through esterification reaction, 3) Methyl ester characterization of rice bran oil and its potential test as biodiesel included determination of density, viscosity, refractive index, and acid number test, 4) The identification of synthesized methyl esters composition using GC-MS. The results showed that rice bran oil has a yield of 18.09%. Synthesis of methyl esters from rice bran oil through the esterification reaction with a catalyst acid yields 72.37%. The characters of the synthesized methyl ester are on the range of biodiesel quality standards, namely, the density is 0.850 g/mL, viscosity is 4.73 cSt, a refractive index is 1.45871, and an acid number is 0.76 g KOH/g methyl ester, therefore it is claimed that the synthesized methyl esters have the potential as biodiesel. The GC-MS result showed the presence of compounds methyl tetradecanoate (0.38%), methyl hexadecanoate (40.67%), methyl 9-octadecenoate (53.68%), methyl octadecanoate (5.02%), and methyl eicosanoate (0.14%).

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Ghalia, Mohamed H., Mohamed Abd El-Hamid, Mohamed A. Zweil, Abd El-Galil E. Amr, and Shimaa A. Moafi. "Synthesis and Reactions of New Chiral Linear and Macrocyclic Tetraand Penta-peptide Candidates." Zeitschrift für Naturforschung B 67, no. 8 (August 1, 2012): 806–18. http://dx.doi.org/10.5560/znb.2012-0116.

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9a A series of linear and macrocyclic pentapeptide derivatives have been prepared via the coupling of pyridine-2,6-dicarboxylic acid (1) or pyridine-2,6-dicarbonyl dichloride (2) with appropriate amino acid methyl esters. The coupling of 1or 2with aminoacid methyl esters gave the corresponding pyridine dipeptide methyl esters 3, which were hydrolyzed with sodium hydroxide to the corresponding acids 4. The latter compounds 4were coupled with other amino acid methyl esters to afford the corresponding tetrapeptide esters 5, which were hydrolyzed with sodium hydroxide to the corresponding acids 6. Cyclization of tetrapeptide acids with L-lysine methyl ester or with aliphatic diamide derivatives afforded the corresponding cyclic pentapeptide methyl ester derivatives 7and cyclic tetrapeptide diamines 8, respectively. Finally, hydrolysis with 1 N sodium hydroxide or hydrazinolysis with hydrazine hydrate of methyl esters 7afforded the corresponding acids - e and hydrazides 10a - e, respectively

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9

Rajendran, Aravindan, Anbumathi Palanisamy, and Viruthagiri Thangavelu. "Lipase catalyzed ester synthesis for food processing industries." Brazilian Archives of Biology and Technology 52, no. 1 (February 2009): 207–19. http://dx.doi.org/10.1590/s1516-89132009000100026.

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Lipases are one of the most important industrial biocatalyst which catalyzes the hydrolysis of lipids. It can also reverse the reaction at minimum water activity. Because of this pliable nature, it is widely exploited to catalyze the diverse bioconversion reactions, such as hydrolysis, esterification, interesterification, alcoholysis, acidolysis and aminolysis. The property to synthesize the esters from the fatty acids and glycerol promotes its use in various ester synthesis. The esters synthesized by lipase finds applications in numerous fields such as biodiesel production, resolution of the recemic drugs, fat and lipid modification, flavour synthesis, synthesis of enantiopure pharmaceuticals and nutraceuticals. It plays a crucial role in the food processing industries since the process is unaffected by the unwanted side products. Lipase modifications such as the surfactant coating, molecular imprinting to suit for the non-aqueous ester synthesis have also been reported. This review deals with lipase catalyzed ester synthesis, esterification strategies, optimum conditions and their applications in food processing industries.

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10

Arima, Jiro, Yoshiko Uesugi, Misugi Uraji, Masaki Iwabuchi, and Tadashi Hatanaka. "Dipeptide Synthesis by an Aminopeptidase from Streptomyces septatus TH-2 and Its Application to Synthesis of Biologically Active Peptides." Applied and Environmental Microbiology 72, no. 6 (June 2006): 4225–31. http://dx.doi.org/10.1128/aem.00150-06.

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ABSTRACT Dipeptide synthesis by aminopeptidase from Streptomyces septatus TH-2 (SSAP) was demonstrated using free amino acid as an acyl donor and aminoacyl methyl ester as an acyl acceptor in 98% methanol (MeOH). SSAP retained its activity after more than 100 h in 98% MeOH, and in the case of phenylalanyl-phenylalanine methyl ester synthesis, the enzyme reaction reached equilibrium when more than 50% of the free phenylalanine was converted to the product. In an investigation of the specificity of SSAP toward acyl donors and acyl acceptors, SSAP showed a broad specificity toward various free amino acids and aminoacyl methyl esters. Furthermore, we applied SSAP to the synthesis of several biologically active peptides, such as aspartyl-phenylalanine, alanyl-tyrosine, and valyl-tyrosine methyl esters.

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11

Uno, Takuya, Yusuke Kobayashi, and Yoshiji Takemoto. "N-Heterocyclic carbene-catalyzed direct cross-aza-benzoin reaction: Efficient synthesis of α-amino-β-keto esters." Beilstein Journal of Organic Chemistry 8 (September 10, 2012): 1499–504. http://dx.doi.org/10.3762/bjoc.8.169.

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An efficient catalytic synthesis of α-amino-β-keto esters has been newly developed. Cross-coupling of various aldehydes with α-imino ester, catalyzed by N-heterocyclic carbene, leads chemoselectively to α-amino-β-keto esters in moderate to good yields with high atom efficiency. The reaction mechanism is discussed, and it is proposed that the α-amino-β-keto esters are formed under thermodynamic control.

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12

Jia, Songyan, Minchao Wang, Jiao Ma, Xiumei Liu, Yajing Zhang, and Zhanwei Xu. "Metal chloride mediated efficient conversion of hydroxymethylfurfural (HMF) into long-chain levulinate ester." BioResources 17, no. 1 (December 10, 2021): 849–61. http://dx.doi.org/10.15376/biores.17.1.849-861.

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Levulinate esters are a class of promising alternative fuels derived from biomass. The synthesis of levulinate esters from carbohydrates generally undergoes a route with hydroxymethylfurfural as an intermediate product. The conversion of hydroxymethylfurfural is an intrinsic limiting step for the formation of levulinate esters from carbohydrates. Recent work focuses more on the synthesis of short-chain levulinate esters from biomass, but long-chain levulinate esters have superior properties as fuels. In this work, the synthesis of n-hexyl levulinate, a representative long-chain levulinate ester, was investigated with a series of metal chloride catalysts. Iron chloride (FeCl3) and copper chloride (CuCl2) were found to be the most effective amongst the tested catalysts. An n-hexyl levulinate yield of approximately 65% with 100% hydroxymethylfurfural conversion could be achieved at a temperature of 160 °C after 240 min. This system was also applied to the conversion of hydroxymethylfurfural and other hexanols such as 2-ethyl-1-butanol, cyclohexanol, 2-hexanol, and 3-hexanol. The catalyst in the system was reusable in a consecutive batch mode. Mechanistic study indicated that the production of levulinate ester from hydroxymethylfurfural probably went through levulinic acid as the intermediate.

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13

Forman, Grant S., Adrian Scaffidi, and Robert V. Stick. "An Alternative Synthesis of Some Carbohydrate α-Amino Acids." Australian Journal of Chemistry 57, no. 1 (2004): 25. http://dx.doi.org/10.1071/ch03214.

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Several carbohydrate ketones have been converted into their trichloromethyl-branched tertiary alcohols. A subsequent treatment of these alcohols under Corey–Link conditions (base, sodium azide, methanol) has given rise to α-azido esters, transformable into azido acids, amino esters, and amino acids. An amino ester and an azido acid have been coupled to form a dipeptide.

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González-Granda, Sergio, Taíssa A. Costin, Marcus M. Sá, and Vicente Gotor-Fernández. "Stereoselective Bioreduction of α-diazo-β-keto Esters." Molecules 25, no. 4 (February 19, 2020): 931. http://dx.doi.org/10.3390/molecules25040931.

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Diazo compounds are versatile reagents in chemical synthesis and biology due to the tunable reactivity of the diazo functionality and its compatibility with living systems. Much effort has been made in recent years to explore their accessibility and synthetic potential; however, their preparation through stereoselective enzymatic asymmetric synthesis has been scarcely reported in the literature. Alcohol dehydrogenases (ADHs, also called ketoreductases, KREDs) are powerful redox enzymes able to reduce carbonyl compounds in a highly stereoselective manner. Herein, we have developed the synthesis and subsequent bioreduction of nine α-diazo-β-keto esters to give optically active α-diazo-β-hydroxy esters with potential applications as chiral building blocks in chemical synthesis. Therefore, the syntheses of prochiral α-diazo-β-keto esters bearing different substitution patterns at the adjacent position of the ketone group (N3CH2, ClCH2, BrCH2, CH3OCH2, NCSCH2, CH3, and Ph) and in the alkoxy portion of the ester functionality (Me, Et, and Bn), were carried out through the diazo transfer reaction to the corresponding β-keto esters in good to excellent yields (81–96%). After performing the chemical reduction of α-diazo-β-keto esters with sodium borohydride and developing robust analytical conditions to monitor the biotransformations, their bioreductions were exhaustively studied using in-house made Escherichia coli overexpressed and commercially available KREDs. Remarkably, the corresponding α-diazo-β-hydroxy esters were obtained in moderate to excellent conversions (60 to >99%) and high selectivities (85 to >99% ee) after 24 h at 30 °C. The best biotransformations in terms of conversion and enantiomeric excess were successfully scaled up to give the expected chiral alcohols with almost the same activity and selectivity values observed in the enzyme screening experiments.

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Charlton, James L., Gaiklean Chee, and Heather McColeman. "Synthesis of acetylenedicarboxylic acid esters and asymmetric Diels–Alder reactions of the bis(methyl (S)-lactyl) ester." Canadian Journal of Chemistry 73, no. 9 (September 1, 1995): 1454–62. http://dx.doi.org/10.1139/v95-180.

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A general method has been developed for the preparation of acetylenedicarboxylic acid esters and applied to the synthesis of both achiral and chiral esters. Diels–Alder reactions of one of the chiral esters, the bis(methyl (S)-lactyl) ester, with various types of dienes, such as phenylbutadiene, orthoquinodimethanes, and isobenzofuran, have been investigated. Moderate asymmetric induction was observed in reactions with dienes bearing an α-hydroxyl group. In one case, an unusual solvent-induced reversal of asymmetric induction was observed. Keywords: acetylenedicarboxylic acid esters, phenylbutadiene, orthoquinodimethanes, isobenzofurans, Diels–Alder, asymmetric.

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16

Buzatu, Alina Ramona, August E. Frissen, Lambertus A. M. van den Broek, Anamaria Todea, Marilena Motoc, and Carmen Gabriela Boeriu. "Chemoenzymatic Synthesis of New Aromatic Esters of Mono- and Oligosaccharides." Processes 8, no. 12 (December 11, 2020): 1638. http://dx.doi.org/10.3390/pr8121638.

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An efficient and convenient chemoenzymatic route for the synthesis of novel phenolic mono-, di- and oligosaccharide esters is described. Acetal derivatives of glucose, sucrose, lactose and inulin were obtained by chemical synthesis. The fully characterized pure sugar acetals were subjected to enzymatic esterification with 3-(4-hydroxyphenyl) propionic acid (HPPA) in the presence of Novozyme 435 lipase as a biocatalyst. The aromatic esters of alkyl glycosides and glucose acetal were obtained with good esterification yields, characterized by mass spectrometry (MALDI-TOF MS), infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (1H NMR, 13C NMR). The synthesis of aromatic esters of disaccharide acetals was successful only for the enzymatic esterification of sucrose acetal. The new chemoenzymatic route allowed the synthesis of novel aromatic esters of inulin as the inulin monoacetal monoester and diester and the inulin diacetal monoester with a polymerization degree of two, as well as the inulin monoacetal monoester with a degree of polymerization of three, were obtained by enzymatic acylation of inulin acetals with HPPA. These compounds could represent a new class of sugar ester surfactants with enhanced bioactivity, antioxidative and antimicrobial properties and with potential application in drug delivery systems.

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17

Salimon, Jumat, Neeranjini Nallathamby, Nadia Salih, and Bashar Mudhaffar Abdullah. "Synthesis and Physical Properties of Estolide Ester Using Saturated Fatty Acid and Ricinoleic Acid." Journal of Automated Methods and Management in Chemistry 2011 (2011): 1–4. http://dx.doi.org/10.1155/2011/263624.

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A study was conveyed to produce estolide ester using ricinoleic acid as the backbone. The ricinoleic acid reacted with saturated fatty acid from C8–C18. These reactions were conducted under vacuum at 60°C for 24 h without solvent. The reaction used acid catalyst, sulphuric acid. The new saturate ricinoleic estolide esters show superior low-temperature properties (−52 ± 0.08°C) and high flash point (>300°C). The yield of the neat estolide esters ranged from 52% to 96%. The viscosity range was 51 ± 0.08 to 86 ± 0.01 cp. These new saturated estolide esters were also compared with saturated branched estolide esters.

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18

Pettit, George R., and Paul S. Nelson. "Synthesis of amino acid diazoketones." Canadian Journal of Chemistry 64, no. 11 (November 1, 1986): 2097–102. http://dx.doi.org/10.1139/v86-346.

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A study of carboxylic acid → diazoketone conversion was pursued employing the γ-carboxyl group of otherwise protected L-glutamic acids. The Arndt–Eistert route employing carboxylic acid chloride intermediates was found best (52% yield, 5b), performed at very low temperatures employing oxalyl chloride in dimethylformamide–tetrahydrofuran followed by diazomethane at −23 °C. Alternatively, substitution of a mixed carbonic anhydride for the acyl chloride led to very similar yields (57% of 5b) of diazoketones (5). Among a series of active ester intermediates (7) examined, only the ODnp (7d) and SPfp (7f) esters were found to react (23–26% yield), at least partially, with diazomethane. The latter two reactions appear to represent the first such examples employing active esters.

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19

Baum, James Clayton, Kathleen Anne Durkin, Laura Precedo, Stacy Brian O'blenes, John Edward Goehl, Richard Francis Langler, Gerald Kendall MacCormack, and Lana Louise Smith. "Sulfonyl esters 3. The formation of sulfone-sulfonates in the reactions of aryl methanesulfonates with sodium hydride." Canadian Journal of Chemistry 69, no. 12 (December 1, 1991): 2127–35. http://dx.doi.org/10.1139/v91-307.

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Sodium hydride reductions of aryl methanesulfonates afford dimeric sulfone-sulfonate esters as well as products arising from SO bond rupture. SO bond rupture becomes more competitive as the LUMO energy of the sulfonate ester declines. Exploration of the chemistry of a sulfone-sulfonate ester revealed a complex novel reaction that resulted in the formation of, inter alia, a dichloromethanesulfonate ester and a trichloromethanesulfonate ester. The first successful approaches to the synthesis of the heretofore unknown trichloromethanesulfonates and dichloromethanesulfonates are reported. Key words: sodium hydride reductions, sulfenes, sulfone-sulfonate esters

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20

Mattheis, J. P., J. K. Fellman, P. M. Chen, and M. E. Patterson. "CHANGES IN NON-ETHYLENE VOLATILE SYNTHESIS DURING PHYSIOLOGICAL DEVELOPMENT OF `BISBEE DELICIOUS' APPLES." HortScience 27, no. 6 (June 1992): 593e—593. http://dx.doi.org/10.21273/hortsci.27.6.593e.

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Synthesis of non-ethylene volatiles (NEV) undergoes significant alterations during the transition from vegetative growth to senescence in apple fruit. This change results in a substantial increase in the production of esters characteristic of ripe apples. The relationship between changes in NEV synthesis and other indicators of physiological and horticultural maturity were investigated using `Bisbee Delicious' apples. Analysis of NEV was conducted using headspace sampling and GC-MS. Aldehydes and alcohols were the largest NEV components from pre-climacteric fruit although several esters were detected. The concentration of all NEV components declined to a minimum prior to the onset of the climacteric rise in ethylene synthesis. Initial detection of 2-methyl butylacetate, the major ester in ripening `Bisbee Delicious' fruit, occurred several weeks prior to the onset of the climacteric. The increase in ester synthesis accelerated during the post-climacteric period and the amount of total aldehydes also increased.

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21

Tyler, MI, and MEH Howden. "Synthesis and Structure-Activity Studies of Potential Antitumor Agents Derived From Esters of Phorbol." Australian Journal of Chemistry 40, no. 1 (1987): 193. http://dx.doi.org/10.1071/ch9870193.

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A synthetic study was carried out aimed at elucidating structure-activity relationships amongst naturally occurring esters of phorbol (la) and related daphnane ortho esters which have antitumour activity. The following phorbol esters and epoxy derivatives were prepared with ester groups which were present in the structurally related antitumour natural products: the 12,13,20-tribenzoate (lb), 12,13-dibenzoate ( lc ), 12,13-dibenzoate 20-palmitate (Id), 13-acetate 12,20-dibenzoate (le) and the 12,13,20-tricinnamate (1f of phorbol , and the 6,7-epoxides of the 12,13-dibenzoate (2a) and the 12,13,20-tricinnamate (2b) of phorbol . These compounds were tested against in vivo P388 murine lymphocytic leukaemia (3PS) and were found to have low activity. Various combinations of ester and epoxy groups alone were found to be insufficient to confer 3PS activity on the compounds studied. It was concluded that the presence of other groups, such as a 5-hydroxy group, an ortho ester function, and opening of the cyclopropane ring may be important in enhancing this activity.

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22

Schellenberger, Volker, Ute Schellenberger, and Hans-Dieter Jakubke. "Specific water-soluble substrates for chymotrypsin: Attempts for compensating diminished P1-S1 interactions." Collection of Czechoslovak Chemical Communications 53, no. 11 (1988): 2884–89. http://dx.doi.org/10.1135/cccc19882884.

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N-Maleyl-L-amino acid and peptide esters were synthesized and employed as substrates for α-chymotrypsin. From the kcat/KM values can be suggested that benzyl esters are significantly better substrates than the appropriate methyl esters. Further improvement in the substrate properties results from the introduction of the p-nitrobenzyl ester moiety. The choline ester of benzyloxycarbonyl-L-phenylalanine with the highest kcat/KM value confirmed the P1' leaving group specificity for positively charged residues. From the kinetic data can be concluded that acyl donors with high kcat/KM values, which are useful in kinetically controlled enzymatic peptide synthesis, need not contain aromatic amino acid residues in the P1 position.

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23

Ehlert, Janna, Jenny Kronemann, Nadine Zumbrägel, and Matthias Preller. "Lipase-Catalyzed Chemoselective Ester Hydrolysis of Biomimetically Coupled Aryls for the Synthesis of Unsymmetric Biphenyl Esters." Molecules 24, no. 23 (November 23, 2019): 4272. http://dx.doi.org/10.3390/molecules24234272.

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Lipases are among the most frequently used biocatalysts in organic synthesis, allowing numerous environmentally friendly and inexpensive chemical transformations. Here, we present a biomimetic strategy based on iron(III)-catalyzed oxidative coupling and selective ester monohydrolysis using lipases for the synthesis of unsymmetric biphenyl-based esters under mild conditions. The diverse class of biphenyl esters is of pharmaceutical and technical relevance. We explored the potency of a series of nine different lipases of bacterial, fungal, and mammalian origin on their catalytic activities to cleave biphenyl esters, and optimized the reaction conditions, in terms of reaction time, temperature, pH, organic solvent, and water–organic solvent ratios, to improve the chemoselectivity, and hence control the ratio of unsymmetric versus symmetric products. Elevated temperature and increased DMSO content led to an almost exclusive monohydrolysis by the four lipases Candida rugosa lipase (CRL), Mucor miehei lipase (MML), Rhizopus niveus lipase (RNL), and Pseudomonas fluorescens lipase (PFL). The study was complemented by in silico binding predictions to rationalize the observed differences in efficacies of the lipases to convert biphenyl esters. The optimized reaction conditions were transferred to the preparative scale with high yields, underlining the potential of the presented biomimetic approach as an alternative strategy to the commonly used transition metal-based strategies for the synthesis of diverse biphenyl esters.

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24

Gamboni, Remo, Peter Mohr, Nada Waespe-Šarčevic̀, and Christoph Tamm. "Asymmetric synthesis of α-hydroxy-esters via ester enolates." Tetrahedron Letters 26, no. 2 (January 1985): 203–6. http://dx.doi.org/10.1016/s0040-4039(00)61880-4.

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Rodriguez, K. A., and A. T. Tsin. "Retinyl esters in the vertebrate neuroretina." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 256, no. 1 (January 1, 1989): R255—R258. http://dx.doi.org/10.1152/ajpregu.1989.256.1.r255.

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High-performance liquid chromatography (HPLC) was employed to measure retinyl esters in the vertebrate retina. Both retina and retinal pigment epithelium (RPE) from frog, chicken, and bovine eyes were studied. In comparison to the RPE, the retina possessed a significant level of 11-cis and all trans retinyl palmitate. Using a sensitive radioassay, we also detected the presence of retinyl ester hydrolase (REH) activity in homogenates prepared from both retina and RPE. The rate of retinyl ester hydrolysis in these retinas was sufficiently high to supply retinal chromophores for the metabolic renewal and for the regeneration of visual pigments. In comparison to retinyl esters in the RPE, retinyl esters in the retina are located much closer to the sites of visual pigment synthesis and regeneration. Hence it is possible that these retinyl esters play a more important role in the visual cycle than those in the RPE.

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Ward, J. P. "Synthesis of hydroxy thiol esters from glycidol esters." Chemistry and Physics of Lipids 47, no. 3 (July 1988): 217–24. http://dx.doi.org/10.1016/0009-3084(88)90014-x.

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Xia, Chun-nian, and Wei-xiao Hu. "Synthesis of Caffeic Acid Esters." Journal of Chemical Research 2005, no. 5 (May 2005): 332–34. http://dx.doi.org/10.3184/0308234054323869.

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A new method for the preparation of caffeic acid esters was investigated. Ten caffeic acid esters were prepared by condensation of protocatechualdehyde with malonic acid mono-esters in moderate yield. Malonic acid mono-esters were prepared from the corresponding malonate di-esters. The conformations of compounds are trans (E) form.

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Gurbanov, H. N., L. M. Yusifova, M. A. Mammadyarov, and M. M. Abdullayeva. "Synthesis of esters of oxypropylated 2,2,5,5-tetramethylolcyclopentanol and investigation of them as base of promising lubricating materials." World of petroleum products 02 (2022): 6–10. http://dx.doi.org/10.32758/2782-3040-2022-0-2-06-10.

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At present, with the development of modern technology, the requirements for lubricating oils, especially their viscosity-temperature, thermo-oxidative and lubricating characteristics, are becoming more stringent. In this aspect, the synthesis and study of esters of oxypropylated 2,2,5,5-tetramethylolcyclopentanol (TMCP) with cyclic fragments, active centers, multipolar ester groups is promising, have a certain scientific and practical significance.The esters were synthesized by the esterification reaction of oxypropylated TMCP with aliphatic monocarboxylic acids C4-C8, and their physicochemical, viscosity-temperature, thermal-oxidative and lubricating properties were studied. After determining the viscosity-temperature properties, it was established that they have a low pour point (minus 38-minus 430C), an average viscosity at 1000C (ν100 = 23.50-40.22 mm2/s), a high viscosity index (133-150 units) and flash point (305-3800C). When determining the thermo-oxidative stability of esters, it was found that they have low acid numbers after oxidation (2.51-3.28 mg KOH/g), corrosion of electrodes AK-4 (0.06-0.16 mg/cm2), ШХ -15 (0.08-0.11 mg/cm2) and the precipitate is insoluble in isooctane is low (0.120-0.248% of the mass), the volatility is 0.30-0.50% of the mass. The lubricating properties of esters were also determined: critical load Рк,Н = 750-900, spot wear diameter Di,mm at Р = 196Н = 0.50-0.65. Oxypropylated esters in comparison with reference esters - TMCP ester with caproic acid and pentaerythritol ester (PET) and mixture of fatty acids (MFA) fr. C5-C6 surpass them in almost all parameters, are higher molecular weight and promising, and this makes it possible to create on their basis high-temperature lubricating oils special purpose, components or additives to other lubricating oils.

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Kurz, Thomas, and Detlef Geffken. "Synthesis of 3-Amino(alkoxy)-2,4-dioxo-1,3-oxazolidine-5-carboxylates from Tartronic Esters." Zeitschrift für Naturforschung B 54, no. 5 (May 1, 1999): 667–73. http://dx.doi.org/10.1515/znb-1999-0516.

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The reaction of tartronic esters (1a-d) with 1,1'-carbonyl-di-(1,2,4-triazole), hydrazines or hydroxylamines produces 3-amino/3-alkoxy(aralkoxy)-2,4-dioxo-1,3-oxazolidine-5-carboxylic esters (5,6) which are structurally related to the fungicides Famoxadone (I) and Chlozolinate (II). Under suitable conditions the carboxylic ester of 6 can be converted to a carboxamide (7), carbohydrazide (8) or carbohydroxamic acid (9).

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Zhang, Xia, Lin Li, Jian Rong Huang, Ling Chen, Xiao Xi Li, Guo Qin Liu, and Bing Li. "Enzymatic Synthesis of Naringin Palmitate." Advanced Materials Research 554-556 (July 2012): 1350–56. http://dx.doi.org/10.4028/www.scientific.net/amr.554-556.1350.

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Naringin esters are paid more attention in medical and functional food industry than naringin due to their higher stability and solubility in lipidic environments. Naringin palmitic acid esters were enzymatically synthesized with naringin and palmitic acid. The effects of solvent type, temperature, concentration and types of enzymes and the molar ratio of substrates on the conversion of naringin were investigated. Novozym 435 performed higher catalytic ability in tert-amyl alcohol in the esterification of naringin with palmitic acid. The conversion yield of naringin increased with the increase of temperature (30-70°C) and of the concentration of enzyme. The structure of the naringin palmitate was characterized by FT-IR, 1H-NMR and HPLC-MS. 1H-NMR spectroscopic analysis indicated the presence of an ester bond on the C-6 of the glucose moiety of naringin molecule.

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Pechinsky, S. V., A. G. Kuregyan, and E. T. Oganesyan. "Synthesis of Zeaxanthin Esters." Russian Journal of General Chemistry 90, no. 5 (May 2020): 827–31. http://dx.doi.org/10.1134/s1070363220050114.

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Bukowska, Agnieszka, Wiktor Bukowski, and Beata Mossety-Leszczak. "Synthesis of glycidyl esters." Journal of Chemical Technology & Biotechnology 74, no. 12 (December 1999): 1145–48. http://dx.doi.org/10.1002/(sici)1097-4660(199912)74:12<1145::aid-jctb162>3.0.co;2-a.

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Kamarudin, Nurazreen Shazwin, Harumi Veny, Nailah Fasihah Sidek, Faisal Abnisa, Rozana Azrina Sazali, and Noorhaliza Aziz. "Investigation on Synthesis of Trimethylolpropane (TMP) Ester from Non-edible Oil." Bulletin of Chemical Reaction Engineering & Catalysis 15, no. 3 (October 19, 2020): 808–17. http://dx.doi.org/10.9767/bcrec.15.3.8862.808-817.

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Trimethylolpropane (TMP) ester is an eco-friendly lubricant that fully biodegradable and known as bio lubricant. In this study, TMP ester was produced from waste cooking oil and rubber seed oil through a two-step synthesis approach. The reaction is two stages transesterifications, in which the waste cooking oil and the rubber seed oil were first transesterified with methanol to produce methyl ester, followed by transesterification with TMP using para-Toluenesulfonic acid (p-TSA) as catalyst. Various effects of operating conditions were observed, such as reaction time, temperature and molar ratio of reactants. The TMP ester formation was determined based on the quantity of reactant conversion. The synthesized TMP ester was compared and characterized according to their properties. The results showed that the TMP ester from waste cooking oil (WCO) has shown better conversion compare to TMP ester from rubber seed oil (RSO), within a similar operating condition. The highest TMP ester conversion from WCO is 71%, at temperature of 150 ºC with molar ratio of FAME to TMP of 3:1 and catalyst amount of 2% (wt/wt). In addition, these polyol based esters from WCO and RSO exhibit appropriate basic properties for viscosity when compare with requirement standard of lubricant ISO VG46. Copyright © 2020 BCREC Group. All rights reserved

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Vlasova, Kseniya Yu, Petr Ostroverkhov, Daria Vedenyapina, Tamara Yakimova, Alla Trusova, Galina Yurievna Lomakina, Stepan Sergeevich Vodopyanov, et al. "Liposomal Form of 2,4-Dinitrophenol Lipophilic Derivatives as a Promising Therapeutic Agent for ATP Synthesis Inhibition." Nanomaterials 12, no. 13 (June 23, 2022): 2162. http://dx.doi.org/10.3390/nano12132162.

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Mitochondrial uncoupler 2,4-dinitrophenol (2,4-DNP) is a promising antidiabetic and antiobesity agent. Its clinical use is limited by a narrow dynamic range and accumulation in non-target sensitive organs, which results in whole-body toxicity. A liposomal formulation could enable the mentioned drawbacks to be overcome and simplify the liver-targeted delivery and sustained release of 2,4-DNP. We synthesized 2,4-DNP esters with carboxylic acids of various lipophilic degrees using carboxylic acid chloride and then loaded them into liposomes. We demonstrated the effective increase in the entrapment of 2,4-DNP into liposomes when esters were used. Here, we examined the dependence of the sustained release of 2,4-DNP from liposomes on the lipid composition and LogPoct of the ester. We posit that the optimal chain length of the ester should be close to the palmitic acid and the lipid membrane should be composed of phospholipids with a certain phase transition point depending on the desired release rate. The increased effect of the ATP synthesis inhibition of the liposomal forms of caproic and palmitic acid esters compared to free molecules in liver hepatocytes was demonstrated. The liposomes’ stability could well be responsible for this result. This work demonstrates promising possibilities for the liver-targeted delivery of the 2,4-DNP esters with carboxylic acids loaded into liposomes for ATP synthesis inhibition.

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Tsuji, Hiroaki, and Hisashi Yamamoto. "Synthesis of Dipeptides by Boronic Acid Catalysis." Synlett 29, no. 03 (November 24, 2017): 318–21. http://dx.doi.org/10.1055/s-0036-1589130.

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We have found that a boronic acid catalyzed amidation of an N-hydroxy amino acid methyl ester with amino acid tert-butyl esters gave N-hydroxy dipeptide derivatives in good yields without any racemization. The protecting groups on the nitrogen atom could be easily removed by heterogeneous hydrogenation conditions.

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Korzeniowska, Ewelina. "Synthesis of diphenylphosphinic acid esters." Annales Universitatis Mariae Curie-Sklodowska, sectio AA – Chemia 72, no. 1 (December 8, 2017): 23. http://dx.doi.org/10.17951/aa.2017.72.1.23.

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<p>The development of new methods for the synthesis of organophosphorus compounds is still an important part of organic chemistry due to the high demand for these compounds in organic synthesis as well as in asymmetric catalysis. Most of the methods for the synthesis of these compounds include the reactivity of the phosphorus atom, which depending on the structure might exhibit both electrophilic and nucleophilic properties. Herein, I will present the results concerning synthesis of diphenylphosphinic acid esters.</p>

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Pratap, Amit, Vivek Gaval, Ankita Virulkar, Md Modassir Hussain, and Sachin Solanke. "Tribological Study of Functional Fluids Based on Castor Oil." ASM Science Journal 17 (September 9, 2022): 1–6. http://dx.doi.org/10.32802/asmscj.2022.1080.

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Vegetable oil-based lubricants are environment-friendly options as against conventional lubricants. This paper discusses the synthesis as well as characterisation of esters from ricinoleic acid and sebacic acid whose main source is castor oil. Physicochemical properties, tribological study as well as oxidation study have been carried out for the esters. With the increase in ester chain length, extreme pressure properties, viscosity index and pour point has improved, whereas oxidation stability had a detrimental effect. The coefficient of friction for commercial base stocks was better than any of the studied esters.

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Mozhaitsev, Evgenii S., Alexandra L. Zakharenko, Evgeniy V. Suslov, Dina V. Korchagina, Olga D. Zakharova, Inna A. Vasil'eva, Arina A. Chepanova, et al. "Novel Inhibitors of DNA Repair Enzyme TDP1 Combining Monoterpenoid and Adamantane Fragments." Anti-Cancer Agents in Medicinal Chemistry 19, no. 4 (June 25, 2019): 463–72. http://dx.doi.org/10.2174/1871520619666181207094243.

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Background and Objective: The DNA repair enzyme tyrosyl-DNA-phosphodiesterase 1 (TDP1) is a current inhibition target to improve the efficacy of cancer chemotherapy. Previous studies showed that compounds combining adamantane and monoterpenoid fragments are active against TDP1 enzyme. This investigation is focused on the synthesis of monoterpenoid derived esters of 1-adamantane carboxylic acid as TDP1 inhibitors. Methods: New esters were synthesized by the interaction between 1-adamantane carboxylic acid chloride and monoterpenoid alcohols. The esters were tested against TDP1 and its binding to the enzyme was modeling. Results: 13 Novel ester-based TDP1 inhibitors were synthesized with yields of 21–94%; of these, nine esters had not been previously described. A number of the esters were found to inhibit TDP1, with IC50 values ranging from 0.86–4.08 µM. Molecular modelling against the TDP1 crystal structure showed a good fit of the active esters in the catalytic pocket, explaining their potency. A non-toxic dose of ester, containing a 3,7- dimethyloctanol fragment, was found to enhance the cytotoxic effect of topotecan, a clinically used anti-cancer drug, against the human lung adenocarcinoma cell line A549. Conclusion: The esters synthesized were found to be active against TDP1 in the lower micromolar concentration range, with these findings being corroborated by molecular modeling. Simultaneous action of the ester synthesized from 3,7-dimethyloctanol-1 and topotecan revealed a synergistic effect.

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Ferenczi, Alejandra, Nobuko Sugimoto, and Randolph M. Beaudry. "Emission Patterns of Esters and Their Precursors Throughout Ripening and Senescence in ‘Redchief Delicious’ Apple Fruit and Implications Regarding Biosynthesis and Aroma Perception." Journal of the American Society for Horticultural Science 146, no. 5 (September 2021): 297–328. http://dx.doi.org/10.21273/jashs05064-21.

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The volatile profile of ‘Redchief Delicious’ apple (Malus ×domestica Borkh.) fruit was evaluated at 18 time points from 3 weeks before to 8 weeks after onset of autocatalytic ethylene production to capture the dynamics associated with development from mature green to senescent fruit. Minor amounts of ester production began several days before the onset of ethylene production. Ester production rose rapidly as internal ethylene levels increased beyond 22 nmol·L−1 (0.5 µL·L−1). Peak ester production roughly coincided with maximum ethylene synthesis, declining thereafter. Ester production was further evaluated according to the acid- (alkanoate) and alcohol- (alkyl) derived portions of the ester. The maximum rate of production for a given ester tended to occur later in development as the chain length of the alcohol-derived portion declined. The production rate for many esters paralleled the rate of emanation of their respective alcohol substrates, suggesting that availability of the alcohols limits ester production more than availability of the acid substrates. Combining production rates with sensory descriptors and human sensitivity to individual volatiles permitted approximations of aroma sensations likely engendered by the fruit throughout ripening. Overripe and alcoholic sensations are predicted to increase 2 weeks after the initiation of ripening in response to an increase in the production of ethyl esters. Acetate esters predominated, comprising 50% to 80% of esters throughout maturation and ripening, indicating that the substrate acetyl-CoA may be at saturating levels for alcohol acyl transferase (AAT) at the final step of ester formation. Acetate feeding did not enhance ester production, although label from 13C-acetate was extensively incorporated into esters. The data are consistent with the action of multiple AAT isozymes differing in activity and substrate preference. Incorporation of labeled 13C-acetate into precursors of esters, alcohols, and acids, reflected ester biosynthesis via 1- and 2-carbon chain elongation pathways in ripening ‘Redchief Delicious’ apple fruit.

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Ishak, Nurazwa, Ahmad Firdaus B. Lajis, Rosfarizan Mohamad, Arbakariya B. Ariff, Murni Halim, and Helmi Wasoh. "Kojic acid esters: Comparative review on its methods of synthesis." Journal of Biochemistry, Microbiology and Biotechnology 4, no. 2 (December 30, 2016): 7–15. http://dx.doi.org/10.54987/jobimb.v4i2.304.

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In this paper, the syntheses of kojic acid esters via chemical and enzymatic methods are reviewed. The advantages and disadvantages of chemical process in term of process, safety and efficiency are discussed. In enzymatic process, the significant process parameters related to the synthesis of kojic acid esters such as the lipases, solvent, temperature and water content are highlighted. Possible enzymatic synthesis using solvent and solvent-free system taking into consideration of the difference in these systems involving cost, lipase reusability and efficiency is comparatively reviewed. The possible approach for large scale production using various enzyme reactor designs is also discussed and re-evaluated.

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Zavorotny, V. A., and I. V. Podkovyrova. "Use of Carboxylic Acid Ester as Lubricant Component." Oil and Gas Technologies 135, no. 4 (2021): 7–9. http://dx.doi.org/10.32935/1815-2600-2021-135-4-7-9.

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This paper discusses the use of esters of dicarboxylic acids as components of lubricants. Influence of molecular structure on the properties of ester compositions and the course of the esterification reaction. The theoretical foundations for the production of esters, the synthesis of the ester of caproic acid and butyldiglycol are considered, and the effect of temperature on the esterification process is reflected. Samples of a semi-synthetic oil were prepared, consisting of mineral oil and an ester of various concentrations. The viscosity and density were determined, the viscosity index of the samples under study was calculated. An oil with an optimal concentration of an ester and a high viscosity index was selected.

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Zhu, Zijian, Kai Hu, Siyu Chen, Sirui Xiong, and Yongsheng Tao. "Increase in Fruity Ester Production during Spine Grape Wine Fermentation by Goal-Directed Amino Acid Supplementation." Fermentation 7, no. 4 (October 16, 2021): 231. http://dx.doi.org/10.3390/fermentation7040231.

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The aim of this work was to enhance the levels of fruity esters in spine grape (Vitis davidii Foёx) wine by goal-directed amino acid supplementation during fermentation. HPLC and GC-MS monitored the amino acids and fruity esters, respectively, during alcoholic fermentation of spine grape and Cabernet Sauvignon grape. HPLC was also used to determine the extracellular metabolites and precursors involved in the synthesis of fruity esters. Alanine, phenylalanine, and isoleucine levels in spine grape were less than those in Cabernet Sauvignon. Pearson correlation between amino acid profile and fruity ester content in the two systems indicated that deficiencies in alanine, phenylalanine, and isoleucine levels might have limited fruity ester production in spine grape wine. Supplementation of these three amino acids based on their levels in Cabernet Sauvignon significantly increased fruity ester content in spine grape wine. Interestingly, goal-directed amino acid supplementation might have led to changes in the distribution of carbon fluxes, which contributed to the increase in fruity ester production.

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Pieters, M. N., G. R. Castro, D. Schouten, P. Duchateau, J. C. Fruchart, and T. J. C. Van Berkel. "Cholesterol esters selectively delivered in vivo by high-density-lipoprotein subclass LpA-I to rat liver are processed faster into bile acids than are LpA-I/A-II-derived cholesterol esters." Biochemical Journal 292, no. 3 (June 15, 1993): 819–23. http://dx.doi.org/10.1042/bj2920819.

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High-density lipoprotein (HDL) subclass LpA-I has been reported to promote cholesterol efflux from mouse adipose cells in vitro, whereas subclass LpA-I/A-II has no effect. To investigate whether the apolipoprotein composition of HDL plays a role in the selective delivery of cholesterol esters to the liver in vivo, we labelled HDL in its cholesterol ester moiety and separated [3H]cholesterol oleate-labelled HDL into subclasses LpA-I and LpA-I/A-II by immuno-affinity chromatography. Serum decay and liver association of LpA-I and LpA-I/A-II were compared for the apoprotein and cholesterol ester moieties. Both LpA-I and LpA-I/A-II selectively delivered cholesterol esters to the liver with similar kinetics. The kinetics of biliary secretion of processed cholesterol esters, initially associated with LpA-I or LpA-I/A-II, were studied in rats equipped with permanent catheters in bile, duodenum and heart. For both LpA-I and LpA-I/A-II, liver association was coupled to bile acid synthesis, with an increase in secretion rate during the night. During the first night period, the biliary secretion of LpA-I-derived radio-activity was significantly greater than for LpA-I/A-II. The data indicate that with both LpA-I and LpA-I/A-II selective delivery of cholesterol esters from HDL to the liver occurs, but that cholesterol esters delivered by LpA-I are more efficiently coupled to bile acid synthesis.

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Qi, Pengxu, Hsiao-Li Chen, Ha Thi Hoang Nguyen, Chu-Chieh Lin, and Stephen A. Miller. "Synthesis of biorenewable and water-degradable polylactam esters from itaconic acid." Green Chemistry 18, no. 15 (2016): 4170–75. http://dx.doi.org/10.1039/c6gc01081d.

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Polylactam esters are readily made from biobased itaconic acid and are compared to polylactic acid. The lactam ring improves the glass transition temperature and the main-chain ester groups are more readily hydrolyzed, degrading fully via agitation in water for one year.

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Dölling, Karin, Kurt Merzweiler, Christoph Wagner, and Horst Weichmann. "Synthese, Struktur und Reaktivität von 3-Triorganostannyl-N-diphenylmethylen-alaninestern / Synthesis, Structure and Reactivity of 3-Triorganostannyl-N-diphenylmethylenealanine Esters." Zeitschrift für Naturforschung B 54, no. 3 (March 1, 1999): 293–99. http://dx.doi.org/10.1515/znb-1999-0301.

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The deprotonation of N-diphenylmethylene-glycine esters, obtained from glycine ester hydrochlorides and benzophenone imine, and reaction of the resulting carbanions with iodomethyl triorganostannanes gives the 3-triorganostannyl-N-diphenylmethylene-alanine esters Me2RSnCH2CH(N=CPh2)COOR′ (1a - e; R = Me, tBu; R′ = Me, Et, tBu, Bz). These title compounds are transformed into their tin monochlorides MeR(Cl)SnCH2CH(N=CPh2)COOR′ (2a - e) by a redistribution reaction with Me2SnCl2. IR and NMR data and the crystal structure of Me2(Cl)SnCH2CH(N=CPh2)COOEt (2b) reveal for 2a - e an intramolecular coordination of the ester C = 0 group at the tin atom. Mild two-phase hydrolysis of 1a - e with 1N HCl gives the 3-triorganostannyl-alanine ester hydrochlorides Me2RSnCH2CH(NH2)COOR′ · HCl (3a - e). The transformation of 3a - e into the corresponding alanine esters Me2RSnCH2CH(NH2)COOR′ (4a - e) could be realized with NH3 in chloroform. 4a - e are of limited thermal stability.

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Omote, Masaaki, Atsushi Tarui, Masakazu Ueo, Marino Morikawa, Masahiko Tsuta, Sumika Iwasaki, Noriko Morishita, Yukiko Karuo, Kazuyuki Sato, and Kentaro Kawai. "One-Pot Ring-Opening Peptide Synthesis Using α,α-Difluoro-β-Lactams." Synthesis 52, no. 23 (August 17, 2020): 3657–66. http://dx.doi.org/10.1055/s-0040-1707238.

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α,α-Difluoro-β-lactams successfully underwent ring-opening aminolysis with various amino acids in 2,2,2-trifluoroethanol to afford fluorine-containing peptides. In this aminolysis, it was found that 2,2,2-trifluoroethanol first attacked the α,α-difluoro-β-lactams with cleavage of lactam ring to form the corresponding open-chain 2,2,2-trifluoroethyl esters as reactive intermediates. The trifluoroethyl esters were more electrophilic compared with the corresponding methyl ester and thereby accelerated the aminolysis with various amino acids to form β-amino acid peptides with α,α-difluoromethylene unit.

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Liu, Cuibo, Zhongxin Chen, Huan Yan, Shibo Xi, Kah Meng Yam, Jiajian Gao, Yonghua Du, et al. "Expedient synthesis of E-hydrazone esters and 1H-indazole scaffolds through heterogeneous single-atom platinum catalysis." Science Advances 5, no. 12 (December 2019): eaay1537. http://dx.doi.org/10.1126/sciadv.aay1537.

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Unprotected E-hydrazone esters are prized building blocks for the preparation of 1H-indazoles and countless other N-containing biologically active molecules. Despite previous advances, efficient and stereoselective synthesis of these compounds remains nontrivial. Here, we show that Pt single atoms anchored on defect-rich CeO2 nanorods (Pt1/CeO2), in conjunction with the alcoholysis of ammonia borane, promotes exceptionally E-selective hydrogenation of α-diazoesters to afford a wide assortment of N-H hydrazone esters with an overall turnover frequency of up to 566 hours−1 upon reaction completion. The α-diazoester substrates could be generated in situ from readily available carboxylic esters in one-pot hydrogenation reaction. Utility is demonstrated through concise, scalable synthesis of 1H-indazole–derived pharmaceuticals and their 15N-labeled analogs. The present protocol highlights a key mechanistic nuance wherein simultaneous coordination of a Pt site with the diazo N═N and ester carbonyl motifs plays a central role in controlling stereoselectivity, which is supported by density functional theory calculations.

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Benneche, Tore, Per Strande, Unni Wiggen, Lars-Olof Öhman, José Ruiz, Enrique Colacio, A. M. Mulichak, et al. "Synthesis of alpha-Haloalkyl Esters from alpha-Arylthioalkyl Esters." Acta Chemica Scandinavica 43 (1989): 74–77. http://dx.doi.org/10.3891/acta.chem.scand.43-0074.

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Miniejew, Catherine, Francis Outurquin, and Xavier Pannecoucke. "Diastereoselective synthesis of aziridine esters via amino selanyl esters." Tetrahedron 62, no. 11 (March 2006): 2657–70. http://dx.doi.org/10.1016/j.tet.2005.12.030.

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Constantino, Mauricio Gomes. "Hydration of Acetylenic Esters: Synthesis of β-Keto-Esters." Molecules 1, no. 5 (October 31, 1996): 72–78. http://dx.doi.org/10.1007/s007830050012.

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Journal articles on the topic 'Esters – Synthesis'

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