Search results for "Reagent"

Cobalt−NHC Catalyzed C(sp 2 )−C(sp 3 ) and C(sp 2 )−C(sp 2 ) Kumada Cross‐Coupling of Aryl Tosylates with Alkyl and Aryl Grignard Reagents

2020

A detailed MSn study for the molecular identification of a dimer formed from oxidation of pinene

2016

Abstract Dimeric products formed in the oxidation of α- and β-pinene have been frequently observed in laboratory and field studies of biogenic SOA formation. While their existence is undoubted, their exact chemical structures remain unclear. This study uses a combined two step approach aiming on the molecular identification of the most important of the various dimers that have been observed in biogenic secondary organic aerosol formation, a dimer with the molecular weight 358 g mol−1. The first step is the application of a functional group derivatization technique (esterification) to quantify the number of carboxylic acid groups in the target molecule. Based on the detailed interpretation o…

3'-Arylazido-beta-alanyl-2-azido ATP, a cross-linking photoaffinity label for F1ATPases.

1989

Abstract The synthesis of the 3′-arylazido-2-azido ATP derivative 3′-O-{3-[N-(4-azido-2-nitrophenyl)-amino]propionyl}2-azido-adenosine 5′-triphosphate (2,3′-DiN3ATP) is described. The bifunc­ tional photoreactive ATP analog is characterized spectroscopically. Photoaffinity labeling of F, ATPase from Micrococcus luteus by this analog results in the inactivation of the enzyme and in the formation of higher molecular weight cross-links,

Nickel‐Catalyzed C(sp2)−C(sp3) Kumada Cross‐Coupling of Aryl Tosylates with Alkyl Grignard Reagents

2019

Aryl tosylates are an attractive class of electrophiles for cross‐coupling reactions due to ease of synthesis, low price, and the employment of C−O electrophiles, however, the reactivity of aryl tosylates is low. Herein, we report the Ni‐catalyzed C(sp2)−C(sp3) Kumada cross‐coupling of aryl tosylates with primary and secondary alkyl Grignard reagents. The method delivers valuable alkyl arenes by cross‐coupling with challenging alkyl organometallics possessing β‐hydrogens that are prone to β‐hydride elimination and homo‐coupling. The reaction is catalyzed by an air‐ and moisture stable‐Ni(II) precatalyst. A broad range of electronically‐varied aryl tosylates, including bis‐tosylates, underwe…

Synthesis of cyanoacetic acid by carbon dioxide and electrogenerated acetonitrile anion in undivided cells equipped with sacrificial anodes

2008

The electrochemical synthesis of cyanoacetic acid was performed by cathodic reduction of tetraalkylammonium salts (R4NX) in acetonitrile in undivided cells equipped with sacrificial anodes with concomitant or subsequent addition of carbon dioxide. These syntheses avoid the use of dangerous reagents, yield cyanoacetic acid in moderate faradic yields and confirm that the cathodic reduction of tetraalkylammonium salts in the presence of acetonitrile leads to the formation of the anion CNCH2-.

Methacrylate monolithic columns functionalized with epinephrine for capillary electrochromatography applications.

2013

Epinephrine-bonded polymeric monoliths for capillary electrochromatography (CEC) were developed by nucleophilic substitution reaction of epoxide groups of poly(glycidyl-methacrylate-co-ethylenedimethacrylate) (poly(GMA-co-EDMA)) monoliths using epinephrine as nucleophilic reagent. The ring opening reaction under dynamic conditions was optimized. Successful chemical modification of the monolith surface was ascertained by in situ Raman spectroscopy characterization. In addition, the amount of epinephrine groups that was bound to the monolith surface was evaluated by oxidation of the catechol groups with Ce(IV), followed by spectrophotometric measurement of unreacted Ce(IV). About 9% of all th…

A practical entry to β-aryl-β-alkyl amino alcohols: application to the synthesis of a potent BACE1 inhibitor

2012

The 1,2-addition of alkyl Grignard reagents to readily available N-tert-butanesulfinyl ketimines, bearing an α-silyloxy substituent, proceeds in high yields and excellent diastereocontrol. The utility of the present method was demonstrated by the synthesis, in enantiomerically pure form, of one recently disclosed β-secretase (BACE1) inhibitor.

Group 14 Metalloles, Ionic Species and Coordination Compounds

2009

1 Introduction 2 Synthesis 3 Organic Chemical Properties of Group 14 Metalloles 4 Polymeric Silole-Containing π-Conjugated Systems 5 Ionic Species and Coordination Compounds 6 Addendum 7 Conclusion 8 Acknowledgements Keywords: five-membered heterocyclic dienes; heterocyclopentadienes - heteroles or metalloles; group 14 metalloles, ionic species and coordination compounds; gas-phase pyrolysis of silacyclopent-3-enes; organometallic dihalide reaction with dilithio reagent; group 14 metalloles; HOMO stabilization; polymeric silole-containing pi-conjugated systems

New reagent for the detection of sesquiterpene lactones by thin-layer chromatography.

1984

Use of the o-Phthalaldehyde and N-Acetyl-L-Cysteine the Evaluation of Milk Proteins

1991

Abstract o -Phthalaldehyde and N-acetyl-Lcysteine are used in the determination of milk proteins. Three procedures are proposed and compared. One of them is based on reaction of o -phthalaldehyde and N-acetyl-Lcysteine with the intact proteins and the two others on reaction of the reagents with the released amino acids after total acid hydrolysis of the protein samples. When the protein sample is hydrolyzed, calibration is performed either with a hydrolyzed protein standard or with isoleucine. A procedure for the measurement of the degree of enzymatic hydrolysis of milk proteins without separation of the unhydrolyzed protein, which makes use of the same reagents, is also described. In all c…