Synthesis of tricyclic ring systems: [2+2] ketene addition reaction for preparation of tricyclic ketone, alcohol, and lactone derivatives

2017 ◽  
Vol 71 (5) ◽  
pp. 929-938 ◽  
Author(s):  
Özgür Yılmaz ◽  
Esen Yıldız Bekfelavi ◽  
Nermin Şimşek Kuş ◽  
Tuncay Tunç ◽  
Ertan Şahin
Keyword(s):  
Addition Reaction ◽  
Ring Systems ◽  
Tricyclic Ketone

Total Synthesis of (–)-Alstofolinine A: Selected Furan Oxidation/ Cyclization Cascade

Synlett ◽  
2019 ◽  
Vol 31 (01) ◽  
pp. 7-12 ◽  
Author(s):  
Ye Zhang ◽  
Lei Zhang ◽  
Xiangbing Qi
Keyword(s):  
Total Synthesis ◽  
Common Core ◽  
Nucleophilic Addition ◽  
Addition Reaction ◽  
Indole Alkaloids ◽  
Indole Alkaloid ◽  
Asymmetric Total Synthesis ◽  
Ring Systems ◽  
Synthetic Strategy ◽  
Nucleophilic Addition Reaction

Indole-fused tetracyclic ring systems containing nitrogen atoms are common core skeletons of many indole alkaloids such as sarpagine, macroline, and ajmaline. Efficient and stereoselective construction of these ring systems can promote the development of the corresponding alkaloid syntheses. In this article, we briefly summarize our current progress toward the application of the aza-Achmatowicz reaction and indole nucleophilic addition reaction cascade for the first asymmetric total synthesis of the macroline-type indole alkaloid (–)-Alstofolinine A. Our synthetic strategy is based on furan oxidation/rearrangement and proceeds from easily accessible materials such as indole and furan derivatives.

Organonickel(II) complexes containing aryl ligands with chiral pyrrolidinyl ring systems; syntheses and use as homogeneous catalysts for the Kharasch addition reaction

1994 ◽  
Vol 113 (5) ◽  
pp. 267-277 ◽  
Author(s):  
Lucia A. van de Kuil ◽  
Yvonne S. J. Veldhuizen ◽  
David M. Grove ◽  
Jan W. Zwikker ◽  
Leonardus W. Jenneskens ◽  
...  
Keyword(s):  
Addition Reaction ◽  
Homogeneous Catalysts ◽  
Ring Systems

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.

Cupin Variants as Macromolecular Ligand Library for Stereoselective Michael Addition of Nitroalkanes

2019 ◽  
Author(s):  
Nobutaka Fujieda ◽  
Miho Yuasa ◽  
Yosuke Nishikawa ◽  
Genji Kurisu ◽  
Shinobu Itoh ◽  
...  
Keyword(s):  
Michael Addition ◽  
In Silico ◽  
Addition Reaction ◽  
Single Point ◽  
Point Mutations ◽  
Unsaturated Ketone ◽  
Michael Addition Reaction ◽  
Beta Barrel ◽  
Cupin Superfamily ◽  
Single Point Mutations

Cupin superfamily proteins (TM1459) work as a macromolecular ligand framework with a double-stranded beta-barrel structure ligating to a Cu ion through histidine side chains. Variegating the first coordination sphere of TM1459 revealed that H52A and H54A/H58A mutants effectively catalyzed the diastereo- and enantio-selective Michael addition reaction of nitroalkanes to an α,β-unsaturated ketone. Moreover, in silico substrate docking signified C106N and F104W single-point mutations, which inverted the diastereoselectivity of H52A and further improved the stereoselectivity of H54A/H58A, respectively.

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