Ag NMR as a Tool for Mechanistic Studies of Ag-Catalyzed Reactions:  Evidence for in Situ Formation of Alkyn-1-yl Silver from Alkynes and Silver Salts

2005 ◽  
Vol 70 (23) ◽  
pp. 9185-9190 ◽  
Author(s):  
Ulla Létinois-Halbes ◽  
Patrick Pale ◽  
Stefan Berger
Keyword(s):  
Mechanistic Studies ◽  
Silver Salts ◽  
In Situ Formation ◽  
Catalyzed Reactions

scholarly journals Gold(I)-catalyzed intramolecular cyclization/intermolecular cycloaddition cascade as a fast track to polycarbocycles and mechanistic insights

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Cheng Zhang ◽  
Kemiao Hong ◽  
Chao Pei ◽  
Su Zhou ◽  
Wenhao Hu ◽  
...  
Keyword(s):  
Fast Track ◽  
Cycloaddition Reaction ◽  
Structural Diversity ◽  
Mechanistic Studies ◽  
Reaction Conditions ◽  
In Situ Formation ◽  
Increasing Demand ◽  
High Yields ◽  
Synthetic Intermediate

AbstractMetal carbene is an active synthetic intermediate, which has shown versatile applications in synthetic chemistry. Although a variety of catalytic methods have been disclosed for the generation of carbene species from different precursors, there is an increasing demand for the development of efficient and practical approaches for the in-situ formation of metal carbene intermediates with structural diversity and unrevealed reactivity. Herein we report a gold-catalyzed cascade protocol for the assembly of polycarbocyclic frameworks in high yields under mild reaction conditions. Mechanistic studies indicate that the unique β-aryl gold-carbene species, generated via gold-promoted 6-endo-dig diazo-yne cyclization, is the key intermediate in this reaction, followed by a [4 + 2]-cycloaddition with external alkenes. In comparison to the well-documented metal carbene cycloadditions, this carbene intermediate serves as a 4-C synthon in a cycloaddition reaction. A variety of elusive π-conjugated polycyclic hydrocarbons (CPHs) with multiple substituents are readily accessible from the initially generated products by a mild oxidation procedure.

In situ formation of nucleotide-sugars from simple substrates for glycosyltransferase-catalyzed reactions

2021 ◽  
pp. 336-351
Author(s):  
Damien Bretagne ◽  
Gerd K. Wagner ◽  
Pierre Lafite ◽  
Richard Daniellou
Keyword(s):  
Nucleotide Sugars ◽  
In Situ Formation ◽  
Catalyzed Reactions

scholarly journals Formation of compact systems of super-Earths via dynamical instabilities and giant impacts

2019 ◽  
Vol 491 (4) ◽  
pp. 5595-5620 ◽  
Author(s):  
Sanson T S Poon ◽  
Richard P Nelson ◽  
Seth A Jacobson ◽  
Alessandro Morbidelli
Keyword(s):  
Initial Conditions ◽  
Post Processing ◽  
Significant Modification ◽  
Kepler Mission ◽  
Giant Impacts ◽  
Low Mass ◽  
In Situ Formation ◽  
Dynamical Instabilities ◽  
Gaseous Envelopes

ABSTRACT The NASA’s Kepler mission discovered ∼700 planets in multiplanet systems containing three or more transiting bodies, many of which are super-Earths and mini-Neptunes in compact configurations. Using N-body simulations, we examine the in situ, final stage assembly of multiplanet systems via the collisional accretion of protoplanets. Our initial conditions are constructed using a subset of the Kepler five-planet systems as templates. Two different prescriptions for treating planetary collisions are adopted. The simulations address numerous questions: Do the results depend on the accretion prescription?; do the resulting systems resemble the Kepler systems, and do they reproduce the observed distribution of planetary multiplicities when synthetically observed?; do collisions lead to significant modification of protoplanet compositions, or to stripping of gaseous envelopes?; do the eccentricity distributions agree with those inferred for the Kepler planets? We find that the accretion prescription is unimportant in determining the outcomes. The final planetary systems look broadly similar to the Kepler templates adopted, but the observed distributions of planetary multiplicities or eccentricities are not reproduced, because scattering does not excite the systems sufficiently. In addition, we find that ∼1 per cent of our final systems contain a co-orbital planet pair in horseshoe or tadpole orbits. Post-processing the collision outcomes suggests that they would not significantly change the ice fractions of initially ice-rich protoplanets, but significant stripping of gaseous envelopes appears likely. Hence, it may be difficult to reconcile the observation that many low-mass Kepler planets have H/He envelopes with an in situ formation scenario that involves giant impacts after dispersal of the gas disc.

scholarly journals Method for determining the thermal conductivity of in situ formation rock using drilling cuttings

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065015
Author(s):  
Fu Yi ◽  
Xupeng Qi ◽  
Xuexin Zheng ◽  
Huize Yu ◽  
Wenming Bai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
In Situ Formation

scholarly journals In situ formation of a carbon nanotube buckypaper for improving the interlaminar properties of carbon fiber composites

2021 ◽  
Vol 202 ◽  
pp. 109535
Author(s):  
Yadong Wu ◽  
Xiuyan Cheng ◽  
Shaoyun Chen ◽  
Bo Qu ◽  
Rui Wang ◽  
...  
Keyword(s):  
Carbon Nanotube ◽  
Carbon Fiber ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
In Situ Formation

In Situ Formation of Ag Nanoparticles for Fiber Strain Sensors: Toward Textile-Based Wearable Applications

2021 ◽  
Author(s):  
Hwajoong Kim ◽  
Ammar Shaqeel ◽  
Solbi Han ◽  
Junseo Kang ◽  
Jieun Yun ◽  
...  
Keyword(s):  
Ag Nanoparticles ◽  
Strain Sensors ◽  
In Situ Formation
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