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Search results for: N-Acetyl-S-[2-amino-1-(hydroxymethyl)-2-oxoethyl]-L-cysteine-1,1-dimethylethyl Ester C12H22N2O5S CAS: 1079950-10-9

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#35713949   2022/06/17 To Up

Rhodium(I) Carbene-Promoted Enantioselective C-H Functionalization of Simple Unprotected Indoles, Pyrroles and Heteroanalogues: New Mechanistic Insights.

A rhodium(I)-diene catalyzed highly enantioselective C(sp 2 )-H functionalization of simple unprotected indoles, pyrroles, and their common analogues such as furans, thiophenes, and benzofurans with arylvinyldiazoesters has been developed for the first time. This transformation features unusual site-selectivity exclusively at the vinyl terminus of arylvinylcarbene and enables a reliable and rapid synthetic protocol to access a distinctive class of diarylmethine-bearing α, β-unsaturated esters containing a one or two heteroarene-attached tertiary carbon stereocenter in high yields and excellent enantioselectivities under mild reaction conditions. Mechanistic studies and DFT calculations suggest that, compared to the aniline substrate, the more electron-rich indole substrate lowers the C-C addition barrier and alters the rate-determining step to the reductive elimination, leading to different isotope effect.
Ming-Hua Xu, Tian-Yi Wang, Xiao-Xuan Chen, Dong-Xing Zhu, Lung Wa Chung

1766 related Products with: Rhodium(I) Carbene-Promoted Enantioselective C-H Functionalization of Simple Unprotected Indoles, Pyrroles and Heteroanalogues: New Mechanistic Insights.

100050 ug 1 mL500200 5 G1 mL0.1 mg1001000 1 mL 25 MG

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#35691464   2022/06/09 To Up

RIFM fragrance ingredient safety assessment, cyclohexanecarboxylic acid, 2,2,6-trimethyl-, ethyl ester, (1R,6S)-rel-, CAS Registry Number 22471-55-2.


A M Api, D Belsito, D Botelho, M Bruze, G A Burton, M A Cancellieri, H Chon, M L Dagli, M Date, W Dekant, C Deodhar, A D Fryer, L Jones, K Joshi, M Kumar, A Lapczynski, M Lavelle, I Lee, D C Liebler, H Moustakas, M Na, T M Penning, G Ritacco, J Romine, N Sadekar, T W Schultz, D Selechnik, F Siddiqi, I G Sipes, G Sullivan, Y Thakkar, Y Tokura

2738 related Products with: RIFM fragrance ingredient safety assessment, cyclohexanecarboxylic acid, 2,2,6-trimethyl-, ethyl ester, (1R,6S)-rel-, CAS Registry Number 22471-55-2.

25 G 25 G25 mg 1 G100 mg50 mg10 mg10 mg 1 G1 g10 mg2.5 mg

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#35678427   2022/06/09 To Up

Copper-Catalyzed Stereoselective [4 + 2] Cycloaddition of β,γ-Unsaturated α-Keto Esters and 2-Vinylpyrroles in Water.

An asymmetric [4 + 2] cycloaddition of β,γ-unsaturated α-keto esters with 2-vinylpyrroles in water was developed under the catalysis of a kind of copper complex with a low loading. A series of optically pure 3,4-dihydro-2-pyran derivatives could be obtained in excellent yields, with high diastereoselectivities and enantioselectivities. The corresponding mechanism was proposed, which was supported by DFT calculations.
Shuangshuang Zhao, Kuiliang Li, Xiang Sun, Zhenggen Zha, Zhiyong Wang

2683 related Products with: Copper-Catalyzed Stereoselective [4 + 2] Cycloaddition of β,γ-Unsaturated α-Keto Esters and 2-Vinylpyrroles in Water.

5 G5 g400Tests50μl50mg1 g10 mg 25 G2.5 mg4/120 Packing /sleeve/bo10mg

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#35674804   2022/06/08 To Up

Hydrazone bond-oriented molecularly imprinted nanocomposites for the selective separation of protein via the well-defined recognition sites.

The development of hydrazone bond-oriented epitope imprinting strategy is reported to synthesize the polymeric binders for the selective recognition of a protein-β-microglobulin through either its N- or C-terminal epitope. The dynamic reversibility of hydrazone bond facilitated not only the oriented assembly of the template peptide hydrazides onto the substrate but also the efficient removal of them from the imprinted cavities. The well-defined surface imprinted layer was successfully constructed through the precise control over the polymerization of silicate esters. Binding performance of the C-terminal peptide imprinted nanocomposite was significantly improved after tuning the non-covalent interactions using the sequence-matching aromatic co-monomers. The dissociation constant (K) between the optimized nanocomposite and epitope peptide was 0.5 µmol L. The nanomaterial was utilized for the selective extraction and determination of β-microglobulin from human urine by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and HPLC-UV with satisfied recoveries of 93.1-112.3% in a concentration range 1.0-50.0 μg⋅mL.
Le Sheng, Yulong Jin, Huiqing Hou, Yanyan Huang, Rui Zhao

1817 related Products with: Hydrazone bond-oriented molecularly imprinted nanocomposites for the selective separation of protein via the well-defined recognition sites.

1mg100 U102100 ug/vial500 Units100 ug/vial1 ml100 mg 100ul

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#35655547   2022/04/11 To Up

Highly efficient C(CO)-C(alkyl) bond cleavage in ketones to access esters over ultrathin N-doped carbon nanosheets.

Selective oxidative cleavage of the C(CO)-C bond in ketones to access esters is a highly attractive strategy for upgrading ketones. However, it remains a great challenge to realize this important transformation over heterogeneous metal-free catalysts. Herein, we designed a series of porous and ultrathin N-doped carbon nanosheets (denoted as CN-, where represents the pyrolysis temperature) as heterogeneous metal-free catalysts. It was observed that the fabricated CN-800 could efficiently catalyze the oxidative cleavage of the C(CO)-C bond in various ketones to generate the corresponding methyl esters at 130 °C without using any additional base. Detailed investigations revealed that the higher content and electron density of the graphitic-N species contributed to the excellent performance of CN-800. Besides, the high surface area, affording active sites that are more easily accessed, could also enhance the catalytic activity. Notably, the catalysts have great potential for practical applications because of some obvious advantages, such as low cost, neutral reaction conditions, heterogeneous nature, high efficiency, and broad ketone scope. To the best of our knowledge, this is the first work on efficient synthesis of methyl esters oxidative esterification of ketones over heterogeneous metal-free catalysts.
Manli Hua, Jinliang Song, Xin Huang, Honglei Fan, Tianbin Wu, Qinglei Meng, Zhanrong Zhang, Buxing Han

1415 related Products with: Highly efficient C(CO)-C(alkyl) bond cleavage in ketones to access esters over ultrathin N-doped carbon nanosheets.

196 wells (1 kit)4 Membranes/Box4 Arrays/Slide4 Arrays/Slide4 Membranes/Box2 Pieces/Box2 Pieces/Box104 Membranes/Box4 Arrays/Slide

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#35616012   2022/05/26 To Up

An Interlayer Containing Dissociated LiNO with Fast Release Speed for Stable Lithium Metal Batteries with 400 Wh kg Energy Density.

Lithium metal is an ideal electrode material for future rechargeable batteries. However, dendrite formation and unstable solid electrolyte interphase film lead to safety concerns and poor Coulombic efficiency (CE). LiNO significantly improves the performance of the lithium metal anode in ester electrolytes but its use is restricted by low solubility. To increase the content of LiNO in the cell, a poly-(vinyl carbonate) organogel interlayer containing dissociated LiNO (LNO-PVC) is placed between the cathode and anode. The dissociated LiNO effectively increases the LiNO -release rate and compensates for the LiNO consumed in ester electrolytes during cycling. Via this interlayer, the performance of the lithium metal anode is significantly improved. The average CE of a Li-Cu cell reaches 98.6% at 0.5 mA cm -1 h and 98.5% at 1 mA cm -1 h for 300 cycles. Also, a Li||NCM811 pouch cell with LNO-PVC interlayer can also reach a 400 Wh kg energy density with a cycling life of 65 cycles. This strategy sheds light on the effect of the state of this salt on its release/dissolution kinetics, which is determined by the interactions between the salt and host material.
Huicong Yang, Qingyun Liu, Yaozu Wang, Zhuoting Ma, Pei Tang, Xiaoyin Zhang, Hui-Ming Cheng, Zhenhua Sun, Feng Li

1756 related Products with: An Interlayer Containing Dissociated LiNO with Fast Release Speed for Stable Lithium Metal Batteries with 400 Wh kg Energy Density.

100μg100μg100μg100μg100ug Lyophilized100ug Lyophilized100ug100ug Lyophilized 70 Slides 100μg25 µg1 mL

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#35600272   2022/05/16 To Up

Follow-up of the re-evaluation of polyglycerol esters of fatty acids (E 475) as a food additive.

Polyglycerol esters of fatty acids (PEFA, E 475) was re-evaluated in 2017 by the former EFSA Panel on Food Additives and Nutrient sources added to Food (ANS). As a follow-up to this assessment, in this opinion, the Panel on Food Additives and Flavouring (FAF) addresses the data gaps identified to support an amendment of the EU specifications for E 475. The Panel performed a risk assessment of undesirable impurities and constituents potentially present in E 475. The Panel concluded that the maximum limits in the EU specifications for the 4 toxic elements (arsenic, lead, mercury and cadmium) should be lowered based on actual levels in the commercial food additive E 475. The Panel also concluded that maximum limits for erucic acid, 3-monochloropropanediol and glycidyl esters should be included in the EU specifications for E 475. Alternatively, the Panel recommends an amendment of the definition of E 475 to include a requirement that the fats and oils used in the manufacturing of E 475 comply with the respective EU legislation regarding suitability for human consumption. Further, the Panel concluded that there is no need for setting a specification limit for the content of -fatty acids in E 475 as a limit is established in the Regulation (EU) No 2019/649, i.e. 2 g of -fat per 100 g fat in food for the final consumer. Finally, the Panel recommends a modification of the definition of E 475 indicating that polyglycerol used for the manufacturing of E 475 should be produced from glycerol meeting the specifications for E 422 (Commission Regulation (EU) No 231/2012). In this case, respective specification limits for epichlorohydrin, acrolein and butanetriol would not be needed for E 475.
, Maged Younes, Gabriele Aquilina, Laurence Castle, Karl-Heinz Engel, Paul Fowler, Maria Jose Frutos Fernandez, Ursula Gundert-Remy, Rainer Gürtler, Trine Husøy, Melania Manco, Wim Mennes, Peter Moldeus, Sabina Passamonti, Romina Shah, Ine Waalkens-Berendsen, Detlef Wölfle, Matthew Wright, Karlien Cheyns, Manuela Mirat, Ana Maria Rincon, Peter Fürst

2592 related Products with: Follow-up of the re-evaluation of polyglycerol esters of fatty acids (E 475) as a food additive.

430 tests100tests1,000 tests1001000 assays100100ug Lyophilized100 assays

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#35583752   2022/05/18 To Up

Distribution, sources, and ecological risk of organophosphate esters in the urbanized Jiaozhou Bay, East China.

Organophosphate esters (OPEs), substitutes of polybrominated diphenyl ethers, have been found in a variety of marine environmental matrices, whereas little is known about the feature and sources of seawater OPEs from the environments simultaneously affected by multiple anthropogenic activities. Jiaozhou Bay is one typical bay heavily disturbed by human activities, which was semi-enclosed and surrounded by large amounts of discharged rivers and catchments, various types of ports, and aquaculture farms. This study found that concentrations of ΣOPEs ranged from 23.90 to 366.40 ng/L (median: 37.76 ng/L) in the seawater and from 90.15 to 1183.14 ng/L (median: 940.61 ng/L) in the inflowing river water. Tris (2-chloroisopropyl) phosphate, triethyl phosphate, and tris (2-chloroethyl) phosphate were the predominant congener, with the percentage of 43.76%, 22.80%, and 14.01%, respectively, in the bay water and 52.47%, 11.31%, and 23.66% in the river water. The overall spatial distribution was characterized by a higher concentration of ΣOPEs and halogenated-OPEs in the nearshore sites and in the inflowing rivers, which were surrounded by urbanized areas with dense anthropogenic activities, especially along the eastern coast. Effluent discharge and vehicular and marine traffic emissions were distinguished as two main plausible sources of OPEs to Jiaozhou Bay, based on the principal component analysis and Spearman correlations. Ecological risk analysis indicated that ΣOPEs posed a low risk to aquatic organisms in the bay and low-to-medium risks in the inflowing rivers.
Jianing Lin, Lutao Zhang, Mingxing Zhang, Heng Zhang, Changsheng Guo, Song Feng, Jian Xu

2338 related Products with: Distribution, sources, and ecological risk of organophosphate esters in the urbanized Jiaozhou Bay, East China.

15mg100 μg

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#35515334   2022/05/04 To Up

Follow-up of the re-evaluation of polyglycerol polyricinoleate (E 476) as a food additive.

Polyglycerol polyricinoleate (PGPR, E 476) was re-evaluated in 2017 by the former EFSA Panel on Food Additives and Nutrient sources added to Food (ANS). As a follow-up to this assessment, in this opinion, the Panel on Food Additives and Flavouring (FAF) addresses the data gaps identified to support an amendment of the EU specifications for E 476. Additionally, this opinion deals with the assessment of the proposed extension of use for E 476 in edible ices and a revision of the maximum permitted level in emulsified sauces. The Panel concluded that the proposed extension of use, if authorised, would not give rise to a safety concern. Additionally, the Panel performed a risk assessment of undesirable impurities potentially present in E 476. The Panel concluded that the maximum limits in the EU specifications for the four toxic elements (arsenic, lead, mercury, cadmium) should be lowered based on actual levels in the commercial food additive E 476. The Panel also concluded that maximum limits for glycidyl esters and 3-monochloropropanediol should be included in the EU specifications for E 476. Alternatively, the Panel recommends an amendment of the definition of E 476 to include a requirement that the fats and oils used in the manufacturing of E 476 comply with the respective EU legislation regarding suitability for human consumption. Further, the Panel recommends a modification of the definition of E 476 indicating that polyglycerol used for the manufacturing of E 476 should be produced from glycerol meeting the specifications for E 422 (Commission Regulation (EU) No 231/2012). In this case, respective specification limits for epichlorohydrin, acrolein and butanetriol would not be needed for E 476. Finally, the Panel concluded that the proposed method based on the determination of ricinoleic acid is suitable for the determination of E 476 content in food.
, Maged Younes, Gabriele Aquilina, Laurence Castle, Karl-Heinz Engel, Paul Fowler, Maria Jose Frutos Fernandez, Ursula Gundert-Remy, Rainer Gürtler, Trine Husøy, Melania Manco, Wim Mennes, Peter Moldeus, Sabina Passamonti, Romina Shah, Ine Waalkens-Berendsen, Detlef Wölfle, Matthew Wright, Karlien Cheyns, Manuela Mirat, Ana Maria Rincon, Alexandra Tard, Peter Fürst

1473 related Products with: Follow-up of the re-evaluation of polyglycerol polyricinoleate (E 476) as a food additive.

96 well100 tests1000.5 ml1 kit10010 plates100100ug900 tests

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#35486985   2022/04/15 To Up

Triacylglycerols containing branched palmitic acid ester of hydroxystearic acid (PAHSA) are present in the breast milk and hydrolyzed by carboxyl ester lipase.

Breast milk is a complex mixture containing underexplored bioactive lipids. We performed an observational case-control study to compare the impact of delivery mode: caesarean section (CS) and vaginal birth (VB); and term (preterm and term delivery) on the levels of lipokines in human milk at different stages of lactation. Metabolomic analysis of the milk identified triacylglycerol estolides as a metabolic reservoir of the anti-inflammatory lipid mediator 5-palmitic acid ester of hydroxystearic acid (5-PAHSA). We found that triacylglycerol estolides were substrates of carboxyl ester lipase and 5-PAHSA-containing lipids were the least preferred substrates among tested triacylglycerol estolide isomers. This explained exceptionally high colostrum levels of 5-PAHSA in the VB group. CS and preterm birth negatively affected colostrum lipidome, including 5-PAHSA levels, but the lipidomic profiles normalized in mature milk. Mothers delivering term babies vaginally produce colostrum rich in 5-PAHSA, which could contribute to the prevention of intestinal inflammation in newborns.
Kristyna Brejchova, Veronika Paluchova, Marie Brezinova, Tomas Cajka, Laurence Balas, Thierry Durand, Marcela Krizova, Zbynek Stranak, Ondrej Kuda

1399 related Products with: Triacylglycerols containing branched palmitic acid ester of hydroxystearic acid (PAHSA) are present in the breast milk and hydrolyzed by carboxyl ester lipase.

10 mg25 mg25 mg10 mg250 mg96T10 mg1 g10 mg25 mg25 mg2.5 mg

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