Ring-Closing Alkyne Metathesis Approach toward the Synthesis of Alkyne Mimics of Thioether A-, B-, C-, and DE-Ring Systems of the Lantibiotic Nisin Z

2005 ◽  
Vol 7 (14) ◽  
pp. 2961-2964 ◽  
Author(s):  
Nourdin Ghalit ◽  
Alex J. Poot ◽  
Alois Fürstner ◽  
Dirk T. S. Rijkers ◽  
Rob M. J. Liskamp
Keyword(s):  
Alkyne Metathesis ◽  
Ring Systems ◽  
Nisin Z

Comments on collision mechanics in ring systems

1984 ◽  
Vol 75 ◽  
pp. 407-422
Author(s):  
William K. Hartmann
Keyword(s):  
Asteroid Belt ◽  
Surface Erosion ◽  
Surface Layers ◽  
Ring Systems ◽  
Eclipse Observations ◽  
Saturn’S Rings ◽  
Saturn's Rings

ABSTRACTThe nature of collisions within ring systems is reviewed with emphasis on Saturn's rings. The particles may have coherent icy cores and less coherent granular or frosty surface layers, consistent with thermal eclipse observations. Present-day collisions of such ring particles do not cause catastrophic fragmentation of the particles, although some minor surface erosion and reaccretion is possible. Evolution by collisional fragmentation is thus not as important as in the asteroid belt.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Diverse Cyclopentenes via Enantioselective Cu-Catalyzed Desymmetrization

2018 ◽  
Author(s):  
Reece Jacques ◽  
Robert D. C. Pullin ◽  
Stephen P. Fletcher
Keyword(s):  
Ring Systems ◽  
Quaternary Centers ◽  
Stereogenic Centers

<div> <div> <div> <p>A highly regio-, diastereo- and enantioselective Cu-catalyzed desymmetrization of diverse meso-bisphosphates with alkyl zirconium nucleophiles has been developed. The reaction allows access to a broad range of functionalized cyclopentenes with up to three contiguous stereogenic centers, including quaternary centers and spirocyclic ring systems.</p></div></div></div>

Diverse Cyclopentenes via Enantioselective Cu-Catalyzed Desymmetrization

2018 ◽  
Author(s):  
Reece Jacques ◽  
Robert D. C. Pullin ◽  
Stephen P. Fletcher
Keyword(s):  
Ring Systems ◽  
Quaternary Centers ◽  
Stereogenic Centers

<div> <div> <div> <p>A highly regio-, diastereo- and enantioselective Cu-catalyzed desymmetrization of diverse meso-bisphosphates with alkyl zirconium nucleophiles has been developed. The reaction allows access to a broad range of functionalized cyclopentenes with up to three contiguous stereogenic centers, including quaternary centers and spirocyclic ring systems.</p></div></div></div>

Synthesis of Conjugated Triynes via Alkyne Metathesis

2019 ◽  
Author(s):  
Idriss Curbet ◽  
Sophie Colombel-Rouen ◽  
Romane Manguin ◽  
Anthony Clermont ◽  
Alexandre Quelhas ◽  
...  
Keyword(s):  
Steric Hindrance ◽  
High Selectivity ◽  
Alkyne Metathesis ◽  
Cross Metathesis ◽  
Synthetic Strategy ◽  
Sterically Hindered ◽  
Site Selective

<div> <div> <div> <div> <p>The synthesis of conjugated triynes by molybdenum-catalyzed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site- selective alkyne metathesis to produce the desired con- jugated triyne products. The steric hindrance of alkyne moiety was found to be crucial in preventing the for- mation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity. </p> </div> </div> </div> </div>

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