Furanosyl Oxocarbenium Ion Stability and Stereoselectivity

2014 ◽  
Vol 53 (39) ◽  
pp. 10381-10385 ◽  
Author(s):  
Erwin R. van Rijssel ◽  
Pieter van Delft ◽  
Gerrit Lodder ◽  
Herman S. Overkleeft ◽  
Gijsbert A. van der Marel ◽  
...  
Keyword(s):  
Oxocarbenium Ion ◽  
Ion Stability

Furanosyl Oxocarbenium Ion Stability and Stereoselectivity

2014 ◽  
Vol 126 (39) ◽  
pp. 10549-10553 ◽  
Author(s):  
Erwin R. van Rijssel ◽  
Pieter van Delft ◽  
Gerrit Lodder ◽  
Herman S. Overkleeft ◽  
Gijsbert A. van der Marel ◽  
...  
Keyword(s):  
Oxocarbenium Ion ◽  
Ion Stability

Influencing Factors of Chromium Ion Stability in Microbe Culture Media

2012 ◽  
Vol 610-613 ◽  
pp. 215-219
Author(s):  
Yun Xiao He ◽  
Xiao Ming Chen
Keyword(s):  
Ionic Liquid ◽  
Liquid Medium ◽  
Culture Media ◽  
Fluid Medium ◽  
Chromium Ion ◽  
Medium Components ◽  
Salt Ions ◽  
Ion Stability ◽  
The Stability ◽  
Ionic Liquid Medium

The stability factors for Cr6+ and Cr3+ in microbiological media, including temperature, preservation conditions and medium components were studied in this research project, through potassium permanganate oxidation and DPC (Diphenylcarbazide) spectrophotometry. It shows that the protein component mainly influences Cr6+ content changes at pre- and post- heat sterilization to the chromium ionic liquid medium, other than being impacted basically by inorganic salt ions. It also indicates that the method can be introduced into experiment researches for microbe dechromisation i.e. Chromium ion aqueous solution and fluid medium are sterilized separately, and then are made into the chrome ions liquid as per a certain concentration. The concentration of hexavalent chromium ions is affected by preservation time and temperature also. For this reason, chromium ionic liquid medium is kept at low temperature, and as quickly as possible for the test.

Mechanistic Study on Gold(I)-Catalyzed Unsaturated Spiroketalization Reaction

2022 ◽  
Vol 19 ◽  
Author(s):  
Kamlesh Sharma
Keyword(s):  
Activation Barrier ◽  
Ring Formation ◽  
Hydroxyl Group ◽  
Mechanistic Study ◽  
Protecting Group ◽  
Wide Range ◽  
Oxocarbenium Ion ◽  
Metal Catalyzed ◽  
Insight Into ◽  
Mechanism Of The Reaction

Abstract: The mechanism of metal-catalyzed spiroketalization of propargyl acetonide is explored by employing DFT with the B3LYP/6-31+G(d) method. Acetonide is used as a regioselective regulator in the formation of monounsaturated spiroketal. The energies of transition states, intermediates, reactants and products are calculated to provide new insight into the mechanism of the reaction. The energetic features, validation of the observed trends in regioselectivity are conferred in terms of electronic indices via FMO analysis. The presence of acetonide facilitates a stepwise spiroketalization as it masks the competing nucleophile, and thus hydroxyl group present, exclusively acts as a nucleophile. The vinyl gold intermediate 3 is formed from 2 via activation barrier TS1. This is the first ring formation, which is 6-exo-dig cyclization. The intermediate 3 is converted into allenyl ether 4, which isomerizes to the intermediate oxocarbenium ion 5 via activation barrier TS2. The intermediate 5 cyclizes to 6 via TS3. This is the second ring formation. The intermediate 6 on protodeauration turns into 6,6-monounsaturated spiroketal 7. It is concluded that acetonide as a protecting group serves the purpose, and thus a wide range of spiroketals can be prepared, regioselectivity.

scholarly journals Furanosyl Oxocarbenium Ion Conformational Energy Landscape Maps as a Tool to Study the Glycosylation Stereoselectivity of 2‐Azidofuranoses, 2‐Fluorofuranoses and Methyl Furanosyl Uronates

2019 ◽  
Vol 25 (29) ◽  
pp. 7149-7157 ◽  
Author(s):  
Stefan van der Vorm ◽  
Thomas Hansen ◽  
Erwin R. van Rijssel ◽  
Rolf Dekkers ◽  
Jerre M. Madern ◽  
...  
Keyword(s):  
Energy Landscape ◽  
Conformational Energy ◽  
Oxocarbenium Ion
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