Azoliniums, Adducts, NHCs and Azomethine Ylides: Divergence in Wanzlick Equilibrium and Olefin Metathesis Catalyst Formation

Azoliniums, Adducts, NHCs and Azomethine Ylides: Divergence in Wanzlick Equilibrium and Olefin Metathesis Catalyst Formation

NHC vs. azomethine ylide: A pentafluorophenyl NHC adduct cleanly generates corresponding N-heterocyclic carbene and a new olefin metathesis catalyst, which provides high TONS at PPM levels of loading. Both a Wanzlick and an azomethine ylide dimerization are successfully demonstrated, with the mechanism being determined by either the adduct or the azolinium NHC precursor.

[Communication]
Phillip I. Jolly, Anna Marczyk, Paweł Małecki, Osman Ablialimov, Damian Trzybiński, Krzysztof Woźniak, Silvio Osella, Bartosz Trzaskowski, Karol Grela
Chem. Eur. J., March 14, 2018, https://doi.org/10.1002/chem.201706036 Read article

A Novel Post-Synthesis Modification of CuO-CeO2 Catalysts: Effect on Their Activity for Selective CO Oxidation

A Novel Post‐Synthesis Modification of CuO‐CeO2 Catalysts: Effect on Their Activity for Selective CO Oxidation

Selective CO oxidation: CuO-CeO2 catalysts were modified via a post-synthesis treatment using ammonia solutions. The catalysts were characterized with a variety of analytical techniques, providing useful information on the effect of the Cu:NH3 ratio on the physicochemical properties. Re-dispersion of the active copper species under extremely basic conditions promoted the reducibility and the oxygen mobility of the catalyst, thus resulting in a more efficient catalyst for selective CO oxidation.

[Full Paper]
Joan Papavasiliou, Michał Rawski, John Vakros, George Avgouropoulos
ChemCatChem, March 08, 2018, https://doi.org/10.1002/cctc.201701968 Read article

Green Synthesis of Rhodium Nanoparticles that are Catalytically Active in Benzene Hydrogenation and 1-Hexene Hydroformylation

Green Synthesis of Rhodium Nanoparticles that are Catalytically Active in Benzene Hydrogenation and 1‐Hexene Hydroformylation

Rhodium nanoparticles (Rh NPs) were prepared from Rh(acac)(CO)2 in water at 80 °C. The NPs were stabilized by polyvinylpyrrolidone (PVP) or polyvinyl alcohol (PVA) and characterized by TEM, XPS, and XRD. The excellent catalytic activity of these Rh NPs was evidenced in the hydrogenation of benzene to cyclohexane. Rh NPs were also synthesized using Rh2(OAc)4 and RhCl3, and their catalytic activity was compared.

[Full Paper]
Waleed Alsalahi, Wlodzimierz Tylus, Anna M. Trzeciak
ChemCatChem, March 07, 2018, https://doi.org/10.1002/cctc.201701644 Read article

Size Does Matter—Mediation of Electron Transfer by Gold Clusters in Bioelectrocatalysis

Size Does Matter—Mediation of Electron Transfer by Gold Clusters in Bioelectrocatalysis

Size does matter: We report that redox activity of the gold nanoparticles may contribute to the ET mechanism of an enzyme, switching it to Au cluster mediated electron transfer between the active site and the electrode instead of direct ET as shown for fructose dehydrogenase. The presence gold clusters lead to the increase of catalytic reaction rate constant, kcat 2.5-fold and to a 100 mV reduction in the reaction overpotential.

[Communication]
Michal Kizling, Maciej Dzwonek, Agnieszka Więckowska, Renata Bilewicz
ChemCatChem, March 05, 2018, https://doi.org/10.1002/cctc.201800032 Read article

Synthesis and Biological Evaluation of Imidazole-Bearing α-Phosphonocarboxylates as Inhibitors of Rab Geranylgeranyl Transferase (RGGT)

Synthesis and Biological Evaluation of Imidazole‐Bearing α‐Phosphonocarboxylates as Inhibitors of Rab Geranylgeranyl Transferase (RGGT)

Vesicle traffic light: Novel phosphonocarboxylates bearing imidazole in their structure were synthesized and evaluated for inhibitory activity against Rab geranylgeranyl transferase (RGGT). The preferred positions for modifications in the heterocyclic ring, ensuring micromolar potency toward RGGT, harmonize with bicyclic analogues containing the imidazo[1,2-a]pyridine core.

[Full Paper]
Łukasz Joachimiak, Aleksandra Marchwicka, Edyta Gendaszewska-Darmach, Katarzyna M. Błażewska
ChemMedChem, March 02, 2018, https://doi.org/10.1002/cmdc.201700791 Read article

Cytochrome c Catalyzes the Hydrogen Peroxide-Assisted Oxidative Desulfuration of 2-Thiouridines in Transfer RNAs

Cytochrome c Catalyzes the Hydrogen Peroxide‐Assisted Oxidative Desulfuration of 2‐Thiouridines in Transfer RNAs

The H2O2-promoted desulfuration of 5-substituted 2-thiouridines (R5S2U) [present in the first (wobble) position of the anticodon of transfer RNAs, tRNAs], either alone or within an RNA/tRNA chain, is catalyzed by cytochrome c (cyt c). The presence of uridine sulfenic, sulfinic, and sulfonic acid intermediates in the pathway of the cyt c/H2O2-peroxidase-mediated 2-thiouridine[RIGHTWARDS ARROW]4-pyrimidinone nucleoside transformation is documented.

[Full Paper]
Małgorzata Sierant, Katarzyna Kulik, Elzbieta Sochacka, Rafal Szewczyk, Milena Sobczak, Barbara Nawrot
ChemBioChem, February 14, 2018, https://doi.org/10.1002/cbic.201700692 Read article

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

A nonporous puzzle: A joint experimental and theoretical study sheds more light on the recently discovered permeation of arsenolite by helium under high pressure. It is found that the phenomenon depends on the time given for permeation to take place and on the crystal history, and the thermodynamic driving force for it is also elucidated.

[Article]
Piotr A. Guńka, Michał Hapka, Michael Hanfland, Maciej Dranka, Grzegorz Chałasiński, Janusz Zachara
ChemPhysChem, February 13, 2018, https://doi.org/10.1002/cphc.201701156 Read article

Hydrozirconation of C=X Functionalities with Schwartz's Reagent

Hydrozirconation of C=X Functionalities with Schwartz's Reagent

This Microreview covers the reactions of [Cp2Zr(H)Cl] with C=X functionalities, such as amides, lactams, nitriles or isocyanates, as a method for chemoselective preparation of functionalized organic molecules, for instance aldehydes, amines, and amides.

[Microreview]
Michał M. Więcław, Sebastian Stecko
Eur. J. Org. Chem., January 19, 2018, https://doi.org/10.1002/ejoc.201701537 Read article