ChemInform Abstract: Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper-Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate.

ChemInform ◽  
2014 ◽  
Vol 45 (9) ◽  
pp. no-no
Author(s):  
Fei Ye ◽  
Zhan-Jiang Zheng ◽  
Wen-Hui Deng ◽  
Long-Sheng Zheng ◽  
Yuan Deng ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Zinc Enolate ◽  
P Ligands

Modulation of Multifunctional N,O,P Ligands for Enantioselective Copper-Catalyzed Conjugate Addition of Diethylzinc and Trapping of the Zinc Enolate

2013 ◽  
Vol 8 (9) ◽  
pp. 2242-2253 ◽  
Author(s):  
Fei Ye ◽  
Zhan-Jiang Zheng ◽  
Wen-Hui Deng ◽  
Long-Sheng Zheng ◽  
Yuan Deng ◽  
...  
Keyword(s):  
Conjugate Addition ◽  
Zinc Enolate ◽  
P Ligands

Conjugate addition approach for natural product synthesis inspired by gibberellin and solanoeclepin A targets

2013 ◽  
Vol 85 (6) ◽  
pp. 1149-1160 ◽  
Author(s):  
Minoru Isobe
Keyword(s):  
Oxygen Atom ◽  
Low Temperatures ◽  
Bond Formation ◽  
Conjugate Addition ◽  
Ring Closure ◽  
Natural Product Synthesis ◽  
Partial Synthesis ◽  
Unsaturated Ketones ◽  
Cyclobutane Ring ◽  
Zinc Enolate

Trimethylzincate is known to react through conjugate addition to α,β-unsaturated ketones, but adds much faster to α,β-unsaturated esters at low temperatures. Since the intermediate zinc enolate behaves differently from that of dimethylcuprate, it offers scope for application in a partial synthesis of gibberellin A3. A second example involving vinylsulfones having an oxygen atom on the γ-carbon strongly directs incoming nucleophiles in conjugate addition mode. Heteroatom-directed conjugate addition (HADCA) provides very reactive carbanion intermediates leading to cyclobutane ring formation, necessary for synthesis of solanoeclepin A. An alternative reaction for the four-membered carbocyclic ring closure was explored to make a bond formation between the propargylic cation of Nicholas type and allyltrimethylsilane nucleophile of Hosomi–Sakurai type. This method allowed a formation of tricyclo[5.2.1.01,6]decene framework.

scholarly journals Copper-mediated asymmetric transformations

2002 ◽  
Vol 74 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Alexandre Alexakis
Keyword(s):  
Conjugate Addition ◽  
Organometallic Reagent ◽  
Asymmetric Transformations ◽  
Michael Acceptors ◽  
Catalyzed Reactions ◽  
Zinc Enolate

Copper-catalyzed reactions include the enantioselective conjugate addition and the SN2¢ substitution. We describe the genesis of these reactions, the choice of the primary organometallic reagent, and our studies on finding new Michael acceptors and new ligands. We also report on the use of the zinc enolate generated upon conjugate addition.

Synthesis of Phosphonates, Phosphinates and Tertiary Phosphine Oxides by Pd- or Ni-Catalyzed Microwave-Assisted P–C Coupling Reactions without the Addition of Conventional Ligands

2021 ◽  
Vol 25 ◽  
Author(s):  
Réka Henyecz ◽  
György Keglevich
Keyword(s):  
Tautomeric Form ◽  
Catalyst Precursor ◽  
Coupling Reactions ◽  
Optimum Conditions ◽  
Pd Catalysts ◽  
Catalyst Complex ◽  
Two Factors ◽  
Dialkyl Phosphites ◽  
Catalyst Systems ◽  
P Ligands

Abstract: Microwave (MW)-assistance may be a powerful tool also in the Hirao P–C coupling reactions of vinyl/aryl halides with dialkyl phosphites in the presence of Pd-catalysts/P-ligands elaborated forty years ago. This review surveys the development of this reaction by showing the expansion of the reagents and catalysts, as well as the information accumulated. The stress was laid on the “green” aspects, the simplification of the catalyst systems, and the reliable mechanistic details in order to be able to establish the optimum conditions. The best protocol involves the use of some excess of the >P(O)H reagent to ensure the PdII→Pd0 reduction and, via its trivalent tautomeric form (>POH) also the P-ligand. The overall rate is the result of two factors, the activity of the catalyst complex formed, and the reactivity of the reactants in the P–C coupling reactions. Both components are influenced by the nature of the aryl substituents in Ar2P(O)H. NiII salts may also be used as the catalyst precursor, however, despite the PdII→Pd0→PdII route, in this case, a NiII→NiIV→NiII sequence was proved.

Nickel and Cobalt-Catalyzed Coupling of Alkyl Halides with Alkenes via Heck Reactions and Radical Conjugate Addition

2013 ◽  
Vol 13 (6) ◽  
pp. 802-813 ◽  
Author(s):  
Qun Qian ◽  
Zhenhua Zang ◽  
Yang Chen ◽  
Weiqi Tong ◽  
Hegui Gong
Keyword(s):  
Conjugate Addition ◽  
Alkyl Halides ◽  
Heck Reactions
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