20068-20-6Relevant academic research and scientific papers
Bidentate NHC-based chiral ligands for efficient Cu-catalyzed enantioselective allylic alkylations: Structure and activity of an air-stable chiral Cu complex
Larsen, Andrew O.,Leu, Wenhao,Oberhuber, Christina Nieto,Campbell, John E.,Hoveyda, Amir H.
, p. 11130 - 11131 (2004)
Cu-catalyzed addition of alkylzinc reagents to a range of allylic phosphates is promoted efficiently and with high enantioselectivity to afford tertiary as well as quaternary carbon centers (up to 98% ee). Reactions proceed to completion with 0.5-5 mol % catalyst loading and are best promoted by commercially available CuCl2·2H2O. The X-ray structure of the chiral NHC-Ag(I) complex used in the study as well as that of a catalytically active NHC-Cu(II) complex are also reported; both complexes are air-stable and are formed in ≥95% isolated yield. The isolated Cu complex, which can be handled in air, is catalytically active. The present report provides the first precedent for efficient Cu-catalyzed allylic alkylations with chiral NHC ligands. Copyright
Asymmetric Cross-coupling of Organozinc Reagents with Alkenyl Bromides Catalyzed by a Chiral Ferrocenylphosphine-Palladium Complex
Hayashi, Tamio,Hagihara, Toshiya,Katsuro, Yoshio,Kumada, Makoto
, p. 363 - 364 (1983)
Organozinc reagents, prepared from secondary alkyl Grignard reagents (ArRCHMgCl: Ar=Ph, p-Tol; R=Me, Et) and excess zinc halides, were allowed to react with vinyl bromide and (E)-β-bromostyrene in the presence of dichloro(R)-N,N-dimethyl-1-(S)-2-(diphen
Highly enantioselective copper-catalyzed allylic alkylation with atropos phosphoramidites bearing a D2-symmetric biphenyl backbone
Fang, Fang,Zhang, Hui,Xie, Fang,Yang, Guoqiang,Zhang, Wanbin
, p. 3593 - 3598 (2010)
A novel class of atropos dibridged biphenyl phosphoramidites bearing a D2-symmetric biphenyl backbone was prepared and applied as chiral ligands in the copper-catalyzed allylic alkylation with Grignard reagent. The alkylation products were obtained in quantitative yields with high regioselectivities up to 94:6 of SN2′/SN2 ratio and enantiomeric excesses up to 91.1% for SN2′ products. The unique D2-symmetric backbone ligands have the advantages of easy preparation and sufficient reusability of their key intermediates from the undesired isomers.
Chelating hydroxyalkyl NHC as efficient chiral ligands for room-temperature copper-catalyzed asymmetric allylic alkylation
Jennequin, Thomas,Wencel-Delord, Joanna,Rix, Diane,Daubignard, Julien,Crevisy, Christophe,Mauduit, Marc
, p. 1661 - 1665 (2010)
The application of chiral chelating hydroxy NHC in copper-catalyzed asymmetric allylic alkylation (Cu-AAA) involving various dialkylzincs and allylic phosphate substrates is reported here. From a library of 11 chiral chelating hydroxyalkyl NHC, a fine-tuning has been done to identify the best architectural features enabling to produce the expected γ-adducts in total regioselectivity, good isolated yields, and excellent enantioselectivities (ranging from 93% to >98% ee). Georg Thieme Verlag Stuttgart New York.
From Prochiral N-Heterocyclic Carbenes to Optically Pure Metal Complexes: New Opportunities in Asymmetric Catalysis
Kong, Lingyu,Morvan, Jennifer,Pichon, Delphine,Jean, Marion,Albalat, Muriel,Vives, Thomas,Colombel-Rouen, Sophie,Giorgi, Michel,Dorcet, Vincent,Roisnel, Thierry,Crévisy, Christophe,Nuel, Didier,Nava, Paola,Humbel, Stéphane,Vanthuyne, Nicolas,Mauduit, Marc,Clavier, Hervé
supporting information, p. 93 - 98 (2020/01/09)
Well-defined optically pure transition metal (TM) complexes bearing C1- and C2-symmetric N-heterocyclic carbene (NHC) ligands were prepared from prochiral NHC precursors. As predicted by DFT calculations, our strategy capitalizes on
P-Chiral Monophosphorus Ligands for Asymmetric Copper-Catalyzed Allylic Alkylation
Xiong, Wenrui,Xu, Guangqing,Yu, Xinhong,Tang, Wenjun
supporting information, p. 4003 - 4013 (2019/06/24)
Asymmetric copper-catalyzed allylic alkylation between allyl bromides and alkyl Grignard reagents using a P-chiral monophosphorus ligand is described. A range of terminal olefins bearing tertiary or quaternary carbon centers were formed in good branched/linear selectivities and excellent enantioselectivities at copper loadings as low as 0.5 mol %.
Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
supporting information, p. 11686 - 11689 (2017/11/03)
A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
Improvements and Applications of the Transition Metal-Free Asymmetric Allylic Alkylation using Grignard Reagents and Magnesium Alanates
Grassi, David,Alexakis, Alexandre
supporting information, p. 3171 - 3186 (2015/11/03)
Two new N-heterocyclic carbene (NHC) ligands have been synthesized and employed in the transition metal-free asymmetric allylic alkylation (AAA) mediated by Grignard reagents and magnesium alanates. The employment of these ligands showed high yields and improved regio- and enantioselectivity in the formation of tertiary and quaternary stereocenters. Moreover, the low catalyst loading (up to 0.3 mol%) and high scalability (up to 10 mmol) of this improved methodology provide a convenient access to biologically active compounds and synthetically valuable intermediates.
Metal alkylidene complexes comprising an unsymmetrical unsaturated NHC ligand
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Paragraph 0141, (2015/01/18)
The present invention relates to metal alkylidene complex comprising a 1-aryl-3-alkyl-imidazol-2-ylidene ligand, wherein the aryl group of said 1-aryl-3-alkyl-imidazol-2-ylidene ligand is an aromatic and wherein the alkyl group of said 1-aryl-3-alkyl-imidazol-2-ylidene ligand is selected from the group consisting of a cyclic secondary aliphatic alkyl and a C2-C10-heteroalkyl, and wherein said metal is selected from the group consisting of Pd, Ag, Au, Ir, Rh, Cu, Ni, Mg, Zn, Ti, Pt and Fe, with the provision that the aryl group of said 1-aryl-3-alkyl-imidazol-2-ylidene ligand is other than an ortho-hydroxyaryl group when said metal is Pd and when said cyclic secondary aliphatic alkyl is cyclohexyl.
Bidentate hydroxyalkyl NHC ligands for the copper-catalyzed asymmetric allylic substitution of allyl phosphates with grignard reagents
Magrez, Magaly,Le Guen, Yann,Basle, Olivier,Crevisy, Christophe,Mauduit, Marc
supporting information, p. 1199 - 1203 (2013/02/25)
Demonstrating their potential: Bidentate alkoxy NHC ligands have been used in the copper-catalyzed asymmetric allylic alkylation of allyl phosphates with Grignard reagents (see scheme). The method provides access to tertiary and quaternary chiral centers with high regio- and enantioselectivity. The system is also applied to the synthesis of chiral E,E-dienes, a key structural motif prevalent in natural products. Copyright
