ChemInform Abstract: Catalytic Enantioselective Conjugate Additions of (pin)B-Substituted Allylcopper Compounds Generated in situ from Butadiene or Isoprene.

ChemInform ◽  
2016 ◽  
Vol 47 (51) ◽  
Author(s):  
Xiben Li ◽  
Fanke Meng ◽  
Sebastian Torker ◽  
Ying Shi ◽  
Amir H. Hoveyda
Keyword(s):  
Conjugate Additions

In Search of New Approaches to Asymmetric Conjugate Addition: Screening Studies on the Use of [Zn(bpy*)X(R)] Reagents and α,β-Unsaturated Amide Michael Acceptors

2007 ◽  
Vol 72 (8) ◽  
pp. 1107-1121 ◽  
Author(s):  
Alexander J. Blake ◽  
Daniela Giunta ◽  
Jonathan Shannon ◽  
Maurizio Solinas ◽  
Francesca Walzer ◽  
...  
Keyword(s):  
Ligand Exchange ◽  
Conjugate Addition ◽  
Nmr Studies ◽  
Conjugate Additions ◽  
New Approaches ◽  
Michael Acceptors ◽  
Derivatives Of ◽  
Moderate Yield ◽  
C Nmr

Conjugate additions of [Zn(bpy*)Cl(Et)] (bpy* = 4,4'-di-tert-butyl-2,2'-bipyridine) to cyclohex-2-en-1-one are promoted by ZnMe2 in 88% ee but in moderate yield under CuI phosphoramidite catalysis. In the absence of ZnMe2 the [Zn(bpy*)Cl(Et)] is inactive indicating a Schlenk-type equilibrium. Other derivatives of [Zn(bpy*)Cl(R)] (R = Bu, 4-methylbenzyl), prepared in situ from [ZnCl(R)] and the bipyridine give low yields due to competing chloride abstraction. 13C NMR studies indicate facile organo-ligand exchange between [Zn(bpy*)(Et)2] and [Zn(bpy*)Cl2] complexes. In the presence of the bipyridine, [ZnBr(allyl)] disproportionates into [Zn(bpy*)Br2] and [Zn(bpy*)(allyl)2] species. In separate studies, simple (E)-MeCH=CHCONMeR (R = Me, OMe) α,β-unsaturated amides undergo asymmetric 1,4-addition of EtMgBr in 75-99% yield and 48-79% ee in the presence of the diphosphines JosiPhos or MeDuPhos and copper(I) sources.

Construction of fully substituted carbon centers containing a heteroatom and a CF3 group via in situ generated p-quinone methides

2021 ◽  
Vol 19 (6) ◽  
pp. 1305-1314
Author(s):  
Kyu Terashima ◽  
Tomoko Kawasaki-Takasuka ◽  
Takashi Yamazaki
Keyword(s):  
Quinone Methides ◽  
Conjugate Additions ◽  
Carbon Centers

Facile and practical construction of heteroatom as well as CF3-containing fully substituted carbon centers was realized by 1,6-conjugate additions of a variety of heteronucleophiles to in situ generated δ-CF3-δ-substituted p-quinone methides.

Conjugate Additions of α,β-Unsaturated Ketones with Arylzinc Species That Form in situ from Diethylzinc and Arylboronic Acids

Synthesis ◽  
2004 ◽  
pp. 1057-1061
Author(s):  
Liu-Zhu Gong ◽  
Lin Dong ◽  
Yan-Jun Xu ◽  
Ai-Qiao Mi ◽  
Yao-Zhong Jiang
Keyword(s):  
Conjugate Additions ◽  
Unsaturated Ketones ◽  
Arylboronic Acids

scholarly journals Catalytic Enantioselective Conjugate Additions of (pin)B-Substituted Allylcopper Compounds Generated in situ from Butadiene or Isoprene

2016 ◽  
Vol 128 (34) ◽  
pp. 10151-10156 ◽  
Author(s):  
Xiben Li ◽  
Fanke Meng ◽  
Sebastian Torker ◽  
Ying Shi ◽  
Amir H. Hoveyda
Keyword(s):  
Conjugate Additions

scholarly journals Catalytic Enantioselective Conjugate Additions of (pin)B-Substituted Allylcopper Compounds Generated in situ from Butadiene or Isoprene

2016 ◽  
Vol 55 (34) ◽  
pp. 9997-10002 ◽  
Author(s):  
Xiben Li ◽  
Fanke Meng ◽  
Sebastian Torker ◽  
Ying Shi ◽  
Amir H. Hoveyda
Keyword(s):  
Conjugate Additions

Conjugate Additions of α,β-Unsaturated Ketones with Arylzinc Species that Form in situ from Diethylzinc and Arylboronic Acids.

ChemInform ◽  
2004 ◽  
Vol 35 (37) ◽  
Author(s):  
Lin Dong ◽  
Yan-Jun Xu ◽  
Liu-Zhu Gong ◽  
Ai-Qiao Mi ◽  
Yao-Zhong Jiang
Keyword(s):  
Conjugate Additions ◽  
Unsaturated Ketones ◽  
Arylboronic Acids

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

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