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1. Determination of individual oligonucleotide impurities by small amine ion pair-RP HPLC MS and MS/MS: n − 1 impurities

Author:
Roussis, Stilianos G.; Rodriguez, Andrew A.; Rentel, Claus
Source:
Journal of chromatography 2021 v.1169 pp. 122611
ISSN:
1570-0232
Subject:
esters,   etc   ; ammonium bicarbonate; oligonucleotides; phosphates;     Show all 4 Subjects
Abstract:
... Ion pair-reversed phase (IP-RP) HPLC is one of the most widely used methods for the analysis of oligonucleotide impurities. The method is compatible with mass spectrometry and has been used to guide the development of improved synthesis and purification approaches. The ability to detect and characterize impurities depends on the reagents and the IP buffer system employed, as each can directly affe ...
DOI:
10.1016/j.jchromb.2021.122611

2. Bio-specific immobilization of enzymes on electrospun PHB nanofibers

Author:
Jang, Sun Ah; Park, Ji Hyun; Lim, Hye Jin; Oh, Joon Young; Ki, Hyeon Bae; Lee, Kyung Jin; Song, Jae Kwang; Kim, Dong-Myung
Source:
Enzyme and microbial technology 2021 v.145 pp. 109749
ISSN:
0141-0229
Subject:
carboxylic ester hydrolases,   etc   ; immobilized enzymes; nanofibers; polyhydroxybutyrate;     Show all 4 Subjects
Abstract:
... Enzyme immobilization provides substantial advantages in terms of improving the efficiency of enzymatic process as well as enhancing the reusability of enzymes. Phasins (PhaPs) are naturally occurring polyhydroxyalkanoate (PHA)-binding proteins, and thus can potentially be used as a fusion partner for oriented immobilization of enzymes onto PHA supports. However, presently available granular PHA s ...
DOI:
10.1016/j.enzmictec.2021.109749

3. Rh-catalyzed asymmetric hydrogenation of α-aryl-β-alkylvinyl esters with chiral ferrocenylphosphine-phosphoramidite ligand

Author:
Dong, Chao; Liu, Dao-Sheng; Zhang, Lei; Hu, Xiang-Ping
Source:
Tetrahedron letters 2021 v.65 pp. 152763
ISSN:
0040-4039
Subject:
esters,   etc   ; catalysts; enantioselectivity; hydrogenation; ligands; mixtures; yields;     Show all 7 Subjects
Abstract:
... An enantioselective Rh-catalyzed hydrogenation of E/Z mixtures of trisubstituted vinyl esters has been disclosed. With a combination of [Rh(COD)₂]BF₄ and a structurally fine-tuning chiral ferrocenylphosphine-phosphoramidite ligand as the catalyst, a variety of E/Z mixtures of α-aryl-β-alkylvinyl esters have been successfully hydrogenated in high yields and with good to high enantioselectivities (u ...
DOI:
10.1016/j.tetlet.2020.152763

4. Dramatic influence of ester steric hindrance on the diastereoselectivity of a Michael addition towards the synthesis of the ABC tricycle of hexacyclinic acid

Author:
Audic, Alexandre; Oriez, Raphaël; Prunet, Joëlle
Source:
Tetrahedron 2021 v.79 pp. 131843
ISSN:
0040-4020
Subject:
esters,   etc   ; chemical reactions; diastereomers; diastereoselectivity; synthesis;     Show all 5 Subjects
Abstract:
... During our studies toward the synthesis of the ABC ring system of hexacyclinic acid, we observed an unexpected influence of the steric bulk of the ester group of the Michael acceptor in a key conjugate addition. We propose an eight-membered ring transition state to explain the formation of the undesired diastereomer in the case of unhindered esters. ...
DOI:
10.1016/j.tet.2020.131843

5. Synthesis of the macrolactone core of the revised structure of palmerolide C

Author:
Vaithegi, Kannan; Pawar, Amit B.; Prasad, Kavirayani R.
Source:
Tetrahedron 2021 v.77 pp. 131768
ISSN:
0040-4020
Subject:
ortho esters,   etc   ; chemical reactions; macrolides; synthesis;     Show all 4 Subjects
Abstract:
... Synthetic efforts towards the total synthesis of the revised structure of marine macrolide palmerolide C is reported. Synthesis of the triol unit present in the C8,C9, C10 positions was achieved from d-ribose while Johnson orthoester rearrangement and a Wittig reaction were used to construct the C1–C7 component of the macrolactone. The key macrolactone unit was assembled using intermolecular Heck ...
DOI:
10.1016/j.tet.2020.131768

6. Reductive intramolecular coupling of phthalimides with esters and ketones by low-valent titanium

Author:
Kise, Naoki; Manto, Tatsuhiro; Sakurai, Toshihiko
Source:
Tetrahedron 2020 v.76 no.52 pp. 131725
ISSN:
0040-4020
Subject:
esters,   etc   ; ketones; titanium;     Show all 3 Subjects
Abstract:
... The reductive intermolecular coupling of phthalimides with esters by low-valent titanium gave five-, six-, and seven-membered cyclized products as α-hydroxyketones and their further reduced ketones. The obtained cyclized products were transformed to alkylideneisoindolin-1-ones. The reductive intermolecular coupling of phthalimides with ketones by low-valent titanium also gave five-, six-, and seve ...
DOI:
10.1016/j.tet.2020.131725

7. Synthesis of selenated isochromenones by AgNO₃-catalyzed three-component reaction of alkynylaryl esters, selenium powder and ArB(OH)₂

Author:
Jin, Guo-Qing; Gao, Wen-Xia; Zhou, Yun-Bing; Liu, Miao-Chang; Wu, Hua-Yue
Source:
RSC advances 2020 v.10 no.51 pp. 30439-30442
ISSN:
2046-2069
Subject:
esters,   etc   ; selenium; synthesis;     Show all 3 Subjects
Abstract:
... Reported is the AgNO₃-catalyzed three-component reaction of alkynylaryl esters, selenium powder and ArB(OH)₂, providing a facile entry to selenated isochromenones. This work highlights the use of selenium powder as a selenium reagent in the synthesis of selenated isochromenones for the first time. ...
DOI:
10.1039/d0ra06016j

8. Solvent-induced selectivity of Williamson etherification in the pursuit of amides resistant against oxidative degradation

Author:
Derr, James B.; Clark, John A.; Morales, Maryann; Espinoza, Eli M.; Vadhin, Sandra; Vullev, Valentine I.
Source:
RSC advances 2020 v.10 no.41 pp. 24419-24424
ISSN:
2046-2069
Subject:
esters,   etc   ; acids; amides;     Show all 3 Subjects
Abstract:
... This article reports two discoveries. (1) 2-Methoxyethanol induces unprecedented selectivity for etherification of 5-hydroxy-2-nitrobenzic acids without forming undesired esters. (2) Such compounds are precursors for amides showing unusual robustness against oxidative degradation, essential for molecular electrets that transfer strongly oxidizing holes at about −6.4 eV vs. vacuum. ...
DOI:
10.1039/d0ra04465b

9. Flash vacuum pyrolysis of acetylenic esters: A mechanistic study

Author:
Al-Awadi, Nouria A.; Mohamed, Asaad S.; Habib, Osama M.; Al-Awadhi, Fatma H.; Al-Jalal, Nader A.; Ibrahim, Yehia A.
Source:
Journal of analytical and applied pyrolysis 2020 v.146 pp. 104778
ISSN:
0165-2370
Subject:
esters,   etc   ; carbenes; pyrolysis;     Show all 3 Subjects
Abstract:
... Products from flash vacuum pyrolysis of eleven acetylenic esters are reported in this study. The mechanism of their pyrolysis is proposed based on the products isolated. These reveal a combination of two main mechanistic approaches. Esters with β-hydrogens favor a retro-ene reaction via a six-membered transition state, the absence of such β-hydrogen leads to a carbene intermediate followed by inse ...
DOI:
10.1016/j.jaap.2020.104778

10. Dairy strains of Anoxybacillus flavithermus inhibit lipase production by Geobacillus stearothermophilus

Author:
Sadiq, Faizan Ahmed; Flint, Steve
Source:
International dairy journal 2021 v.119 pp. 104996
ISSN:
0958-6946
Subject:
carboxylic ester hydrolases,   etc   ; Anoxybacillus flavithermus; Geobacillus stearothermophilus; Pseudomonas aeruginosa; coculture;     Show all 5 Subjects
Abstract:
... In this study, we demonstrated lipase inhibition in two genetically distinct dairy strains of Geobacillus stearothermophilus caused by two dairy strains of Anoxybacillus flavithermus as a result of their growth in coculture, where no effect on the growth of G. stearothermophilus strains was noted. Further investigation showed that cell-free supernatant (CFS) of A. flavithermus strains has potentia ...
DOI:
10.1016/j.idairyj.2021.104996

11. The influence of microbial contamination on rice bran rancidity

Author:
Yu, Cheng-wei; Luo, Ting; Cao, Yu; Wei, Chang-hao; Deng, Ze-yuan
Source:
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2021 v.146 pp. 111468
ISSN:
0023-6438
Subject:
carboxylic ester hydrolases,   etc   ; hydrolysis; lipids; microbial contamination; rancidity; rice bran;     Show all 6 Subjects
Abstract:
... The storage and utilization of rice bran are severely impeded due to the rapid rancidity caused by its lipase. However, little research was carried out to explore other factors for rice bran rancidity. In this study, five Bacilli with lipid hydrolysis abilities were isolated from rice bran and then inoculated into sample to explore the influence of microbial contamination on rancidity. Fresh rice ...
DOI:
10.1016/j.lwt.2021.111468

12. Asymmetric synthesis of intermediate for (1R,2S)-ethyl 1-amino-2-vinylcyclopropanecarboxylate by desymmetrization using engineered esterase from Bacillus subtilis

Author:
Kawabata, Hiroshi; Miyake, Ryoma; Asada, Kuniko; Dekishima, Yasumasa; Miyaike, Mitsuko; Kato, Ryohei
Source:
Journal of bioscience and bioengineering 2021 v.131 no.6 pp. 599-604
ISSN:
1389-1723
Subject:
esters,   etc   ; Bacillus subtilis; enantioselectivity; esterases; models; mutants; stereoselective synthesis; viruses;     Show all 8 Subjects
Abstract:
... (1R,2S)-Ethyl 1-amino-2-vinylcyclopropanecarboxylate (VCPA), is a key intermediate for anti-hepatitis C virus drugs. In this study, we developed an efficient manufacturing method of intermediate for (1R,2S)-VCPA by enzymatic desymmetrization of a malonate diester derivative. In synthesis scheme of VCPA (1S,2S)-1-(ethoxycarbonyl)-2-vinylcyclopropanecarboxylic acid (VCPME) is the monoester intermedi ...
DOI:
10.1016/j.jbiosc.2021.02.004

13. Acyl migration occurrence of palm olein during interesterification catalyzed by sn-1,3 specific lipase

Author:
Zhou, Haiyan; Zhang, Zhen; Lee, Wan Jun; Xie, Xiaodong; Li, Aijun; Wang, Yong
Source:
Lebensmittel-Wissenschaft + [i.e. und] Technologie 2021 v.142 pp. 111023
ISSN:
0023-6438
Subject:
carboxylic ester hydrolases,   etc   ; crystallization; lipid content; palm oils; temperature; triacylglycerols;     Show all 6 Subjects
Abstract:
... Palm olein was enzymatically interesterified (EIE) using sn-1,3 specific lipase and the effect of different reaction conditions on the degree of acyl migration (AMD) was investigated. The AMD increased with the amount of lipase loaded, recording the highest AMD of 63.41% when 11% of lipase was added at 80 °C for 2 h. When the reaction time and temperature was further increased, the AMD remained co ...
DOI:
10.1016/j.lwt.2021.111023

14. Enzyme-functionalized magnetic framework composite fabricated by one-pot encapsulation of lipase and Fe3O4 nanoparticle into metal–organic framework

Author:
Ji, Yuan; Wu, Zhengzhang; Zhang, Peng; Qiao, Meng; Hu, Yi; Shen, Baoxing; Li, Bingzhi; Zhang, Xing
Source:
Biochemical engineering journal 2021 v.169 pp. 107962
ISSN:
1369-703X
Subject:
carboxylic ester hydrolases,   etc   ; acetates; coordination polymers; coprecipitation; encapsulation; magnetism;     Show all 6 Subjects
Abstract:
... Introducing magnetic nanoparticles (MNP) into the enzyme@MOF complex is one of the most promising ways to facilitate enzyme recovery but typically hampered by its complex synthetic process and low loading rate. Using lipase as an example, herein, we reported a mild and quick one-pot strategy to achieve the successful encapsulation of lipase (CRL) and Fe₃O₄ nanoparticle into ZIF-8 to form CRL/MNP@Z ...
DOI:
10.1016/j.bej.2021.107962

15. Customized Fading Scaffolds: Strong Polyorthoester Networks via Thiol–Ene Cross-linking for Cytocompatible Surface-Eroding Materials in 3D Printing

Author:
Herwig, Gordon; Pérez-Madrigal, Maria M.; Dove, Andrew P.
Source:
Biomacromolecules 2021 v.22 no.4 pp. 1472-1483
ISSN:
1526-4602
Subject:
ortho esters,   etc   ; acidity; crosslinking; polylactic acid; three-dimensional printing;     Show all 5 Subjects
Abstract:
... Polyorthoesters are a highly desirable class of cytocompatible materials that are able to rapidly surface-erode. Despite their promise, their mechanical weakness and complex synthesis have limited their processability and application in advanced technologies. Herein, we report a readily accessible family of cross-linked poly(orthoester-thioether) (POETE) materials that are suitable for processing ...
DOI:
10.1021/acs.biomac.0c01668

16. Alkoxide-catalyzed ring expansion of 1,3-cyclobutanediones with aldehydes

Author:
Yamazaki, Mizuki; Yoshimura, Tomoyuki; Matsuo, Jun-ichi
Source:
Tetrahedron letters 2021 v.64 pp. 151804
ISSN:
0040-4039
Subject:
esters,   etc   ; aldehydes; catalysts; catalytic activity; chemical reactions; chemical structure;     Show all 6 Subjects
Abstract:
... 1,3-Cyclobutanediones (dialkyl ketene dimer) reacted with various aromatic aldehydes to give six-membered cyclic β-keto esters by using a catalytic amount of potassium ethoxide. Effects of alkoxide catalysts and spiro cyclic groups at the 2,4-positions of 1,3-cyclobutanediones were investigated. ...
DOI:
10.1016/j.tetlet.2020.151804

17. Pigments from Eustigmatophyceae: an interesting class of microalgae for carotenoid production

Author:
Amaral, Raquel; de Melo, J. Sérgio Seixas; dos Santos, Lília Maria Antunes
Source:
Journal of applied phycology 2021 v.33 no.1 pp. 371-384
ISSN:
0921-8971
Subject:
esters,   etc   ; Characiopsis; Eustigmatophyceae; algology; chlorophyll; health promotion; microalgae; photosynthesis; violaxanthin;     Show all 9 Subjects
Abstract:
... Pigments are a fundamental part of the microalgal cell, with chlorophylls at the center of photosynthesis and carotenoids as accessory pigments. The characteristic pigment profile of the Eustigmatophyceae was one of the evidences which contributed to the segregation of this class of organisms from the Xanthophyceae. Recent findings indicate that eustigmatophyte carotenoids are interesting compound ...
DOI:
10.1007/s10811-020-02312-z

18. The xanthate route to lactams

Author:
Zard, Samir Z.
Source:
Tetrahedron 2021 v.79 pp. 131852
ISSN:
0040-4020
Subject:
esters,   etc   ; alkenes; amino acids; cyclization reactions; heterocyclic compounds; lactams;     Show all 6 Subjects
Abstract:
... Convergent routes to various classes of lactams exploiting the unique radical chemistry of xanthates are described. Emphasis is placed on reactions leading to lactams by direct radical cyclization, by intermolecular additions to alkenes followed by ring closure, and by radical additions to alkenes furnishing amino esters and amino acids precursors that can be converted into lactams by ionic conden ...
DOI:
10.1016/j.tet.2020.131852

19. Total synthesis of (−)-Cryptofolione

Author:
Vaithegi, Kannan; Prasad, Kavirayani R.
Source:
Tetrahedron 2021 v.79 pp. 131842
ISSN:
0040-4020
Subject:
carboxylic ester hydrolases,   etc   ; aldehydes; allylation; enantioselective synthesis; enantioselectivity; isomerization; lactones;     Show all 7 Subjects
Abstract:
... Enantioselective total synthesis of δ-lactone containing natural product (−)-cryptofolione was accomplished from commercially available benzylidene acetone. Key features of the synthesis include lipase mediated resolution of a β-hydroxy ketone intermediate, DBU mediated isomerization of γ,δ-unsaturated aldehyde to α,β-unsaturated aldehyde, Brown allylation and RCM reactions. ...
DOI:
10.1016/j.tet.2020.131842

20. Sustainable synthesis of branched-chain diesters

Author:
Serrano-Arnaldos, Mar; Ortega-Requena, Salvadora; Sánchez, José Ángel; Hernández, Adrián; Montiel, María Claudia; Máximo, Fuensanta; Bastida, Josefa
Source:
Journal of biotechnology 2021 v.325 pp. 91-99
ISSN:
0168-1656
Subject:
esters,   etc   ; alcohols; biocatalysts; biodegradability; biotechnology; evaporation; immobilized enzymes;     Show all 7 Subjects
Abstract:
... Esters from branched alcohols and dicarboxylic linear acids are widely used as lube bases due to their good performance at low temperatures. This work proposes a new process to synthesize bis(2-ethylbutyl) adipate and bis(2-ethylbutyl) sebacate by using the lipase-based catalyst Novozym® 435 in a solvent-free system. Different reaction strategies have been tested in order to minimize 2-ethyl-1-but ...
DOI:
10.1016/j.jbiotec.2020.11.013