An insight into the mechanism of the aerobic oxidation of aldehydes catalyzed by N-heterocyclic carbenes

2014 ◽  
Vol 50 (16) ◽  
pp. 2008-2011 ◽  
Author(s):  
O. Bortolini ◽  
C. Chiappe ◽  
M. Fogagnolo ◽  
P. P. Giovannini ◽  
A. Massi ◽  
...  
Keyword(s):  
Aerobic Oxidation ◽  
Heterocyclic Carbenes ◽  
Esi Ms ◽  
Insight Into

The existence of the key intermediates hypothesized for the N-heterocyclic carbene-catalyzed aerobic oxidation of aldehydes has been proven by ESI-MS (MS) experiments.

Novel Intramolecular CAryl–S Bond Activation by an Electron Rich, Ring-Expanded-NHC-Rh centre: A Combined Experimental and DFT Study

2011 ◽  
Vol 64 (8) ◽  
pp. 1141 ◽  
Author(s):  
Abeer Binobaid ◽  
Kingsley J. Cavell ◽  
Mikhail S. Nechaev ◽  
Benson M. Kariuki
Keyword(s):  
Bond Activation ◽  
Reaction Pathway ◽  
Heterocyclic Carbenes ◽  
Dft Study ◽  
Dft Studies ◽  
X Ray ◽  
Carbene Complex ◽  
Donor Capacity ◽  
Insight Into ◽  
Sulfur Bond

The reaction of (o-MeSPh)-N-functionalized tetrahydropyrimidinium salts with KN(SiMe3)2 and [Rh(COD)Cl]2 in THF leads to the formation of a novel dimeric RhIII bis-carbene complex. The reaction involves the unexpected cleavage/oxidative addition of the aryl-sulfur bond to give dimeric metallated RhIII with bridging MeS< moieties. This unusual reaction is probably a consequence of the sterically imposing structure and strong donor capacity of ring-expanded N-heterocyclic carbenes (RE-NHCs). An X-ray structure of the [(Ph,DIPP-NHC)Rh(Cl)(SMe)2] product complex has been obtained, and DFT studies were undertaken to gain an insight into the reaction pathway.

scholarly journals NHC-catalysed highly selective aerobic oxidation of nonactivated aldehydes

2013 ◽  
Vol 9 ◽  
pp. 602-607 ◽  
Author(s):  
Lennart Möhlmann ◽  
Stefan Ludwig ◽  
Siegfried Blechert
Keyword(s):  
Selective Oxidation ◽  
Aerobic Oxidation ◽  
Environmentally Friendly ◽  
Heterocyclic Carbenes ◽  
Metal Free ◽  
Reaction Proceeds ◽  
Selective Aerobic Oxidation ◽  
Terminal Oxidation ◽  
Oxidation Agent

This publication describes a highly selective oxidation of aldehydes to the corresponding acids or esters. The reaction proceeds under metal-free conditions by using N-heterocyclic carbenes as organocatalysts in combination with environmentally friendly oxygen as the terminal oxidation agent.

Mechanistic insight into the aerobic oxidation of benzyl alcohol catalyzed by the CuII–TEMPO catalyst in alkaline water solution

RSC Advances ◽  
2015 ◽  
Vol 5 (102) ◽  
pp. 83976-83984 ◽  
Author(s):  
R. F. Duan ◽  
L. Cheng ◽  
Q. C. Zhang ◽  
L. S. Ma ◽  
H. Y. Ma ◽  
...  
Keyword(s):  
Benzyl Alcohol ◽  
Density Functional ◽  
Water Solution ◽  
Aerobic Oxidation ◽  
Density Functional Method ◽  
Alcohol Oxidation ◽  
Functional Method ◽  
Alkaline Water ◽  
Mechanistic Insight ◽  
Insight Into

The benzyl alcohol oxidation to benzaldehyde in the alkaline water solution catalyzed by CuII/L–TEMPO catalyst is investigated by density functional method. The favorable mechanisms and the role for the water ​have also been predicted.

scholarly journals Development of validated UHPLC–PDA with ESI–MS-MS method for concurrent estimation of magnoflorine, berbamine, columbamine, jatrorrhizine, palmatine and berberine in Berberis aristata

2021 ◽  
Author(s):  
Ishita A. Basera ◽  
Aboli Girme ◽  
Vijay P. Bhatt ◽  
Ganesh Saste ◽  
Sandeep Pawar ◽  
...  
Keyword(s):  
Research Literature ◽  
Simultaneous Estimation ◽  
Therapeutic Effects ◽  
Isoquinoline Alkaloids ◽  
Esi Ms ◽  
Fragment Ions ◽  
Ich Guidelines ◽  
Negative Ionization ◽  
Concurrent Estimation ◽  
Insight Into

Abstract A validated UHPLC-PDA with an ESI-MS/MS method has been developed for simultaneous estimation of six bioactive alkaloids (magnoflorine, berbamine, columbamine, jatrorrhizine, palmatine and berberine) in the different extracts of the roots of Berberis aristata DC (Family:Berberdiaceae). It is an important medicinal herb native to Northern Himalaya and commonly known as ‘daruharidra’, ‘daruhaldi’, ‘Indian barberry’ or ‘tree turmeric’. An insight into the research literature uncovered reports on isoquinoline alkaloids like magnoflorine, berbamine, columbamine, jatrorrhizine, palmatine, and berberine as major bioactives in B. aristata roots, possessing different pharmacological and therapeutic effects. In the present study, these aforementioned alkaloids were separated on Phenomenex Luna®, 5 µm-C8 analytical column. The HPLC-MS analysis was performed at a flow rate of 0.90 mL min−1. Each alkaloid that is resolved was characterized by precursor ions and fragment ions with electrospray ionization (ESI) source in both positive and negative ionization using scan mode. The limit of detections (LODs) were 0.087, 0.727, 0.035, 0.124, 0.782 and 0.794 μg mL−1 for magnoflorine, berbamine, columbamine, jatrorrhizine, palmatine and berberine, respectively. The proposed UHPLC-PDA method was fully validated according to international (ICH) guidelines and was found to be selective, sensitive and highly accurate for the concomitant estimation of the aforementioned symbolic bio-markers of B. aristata roots.

scholarly journals N-Heterocyclic carbene-functionalized magic number gold nanoclusters

2018 ◽  
Author(s):  
Mina R. Narouz ◽  
Kimberly M. Osten ◽  
Phillip J. Unsworth ◽  
Renee W. Y. Man ◽  
Kirsi Salorinne ◽  
...  
Keyword(s):  
Gold Cluster ◽  
Gold Nanoclusters ◽  
Magic Number ◽  
Heterocyclic Carbenes ◽  
Metallic State ◽  
Metal Nanoclusters ◽  
Structure Property ◽  
Structure Property Relationships ◽  
Improved Stability ◽  
Insight Into

Magic number metal nanoclusters are atomically precise nanomaterials that have enabled unprecedented insight into structure-property relationships in nanoscience. Thiolates are the most common ligand, binding to the cluster via a staple motif in which only central gold atoms are in the metallic state. The lack of other strongly-bound ligands for nanoclusters with different bonding modes has been a significant limitation in the field. Herein, we report a previously unknown ligand for gold (0) nanoclusters: N-heterocyclic carbenes (NHCs), which feature a robust metal-carbon single bond, and impart high stability to the corresponding gold cluster. The addition of a single NHC to gold nanoclusters results in significantly improved stability and catalytic properties in the electrocatalytic reduction of CO<sub>2</sub>. By varying the conditions, nature and number of equivalents of the NHC, predominantly or exclusively monosubstituted NHC-functionalized clusters result. Clusters can also be obtained with up to five NHCs, as a mixture of species.

scholarly journals Aryl bis-sulfonamides bind to the active site of a homotrimeric isoprenoid biosynthesis enzyme IspF and extract the essential divalent metal cation cofactor

2018 ◽  
Vol 9 (27) ◽  
pp. 5976-5986 ◽  
Author(s):  
Katharina Root ◽  
Konstantin Barylyuk ◽  
Anatol Schwab ◽  
Jonas Thelemann ◽  
Boris Illarionov ◽  
...  
Keyword(s):  
Protein Binding ◽  
Metal Cation ◽  
Active Site ◽  
Divalent Metal ◽  
Isoprenoid Biosynthesis ◽  
Divalent Metal Cation ◽  
Esi Ms ◽  
Binding Mechanisms ◽  
Insight Into

Native ESI-MS delivers unprecedented insight into unknown homomeric protein binding mechanisms involving complex, multistage binding equilibria with cofactors and ligands.

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