1092571-60-2Relevant academic research and scientific papers
Recoverable polystyrene-supported palladium catalyst for construction of all-carbon quaternary stereocenters via asymmetric 1,4-addition of arylboronic acids to cyclic enones
Bartá?ek, Jan,Váňa, Ji?í,Drabina, Pavel,Svoboda, Jan,Kocúrik, Martin,Sedlák, Milo?
, (2020/05/16)
The development of recoverable catalysts based on the combination of synthetically demanding ligands with transition metals attracts a lot of attention, especially from the environmental point of view. In this paper, we describe the preparation of a recoverable polystyrene supported chiral palladium catalyst based on PyOx ligand suitable for asymmetric 1,4-addition of arylboronic acids to cyclic 3-substituted five- and six-membered enones. In the reaction, all?carbon quaternary stereocenters are formed with a high level of enantioselectivity (up to 91% ee) and conversion (up to 99%). The catalyst was used in 6 cycles with no loss of enantioselectivity and only a small decrease in conversion. A solution of the problems associated with the transition from homogeneous to heterogeneous catalytic systems is discussed.
Synthesis of diverse β-quaternary ketones via palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enones
Holder, Jeffrey C.,Goodman, Emmett D.,Kikushima, Kotaro,Gatti, Michele,Marziale, Alexander N.,Stoltz, Brian M.
, p. 5781 - 5792 (2015/08/03)
Abstract The development and optimization of a palladium-catalyzed asymmetric conjugate addition of arylboronic acids to cyclic enone conjugate acceptors is described. These reactions employ air-stable and readily-available reagents in an operationally si
Palladium-catalyzed asymmetric conjugate addition of arylboronic acids to five-, six-, and seven-membered β-substituted cyclic enones: enantioselective construction of all-carbon quaternary stereocenters
Kikushima, Kotaro,Holder, Jeffrey C.,Gatti, Michele,Stoltz, Brian M.
supporting information; experimental part, p. 6902 - 6905 (2011/06/19)
The first enantioselective Pd-catalyzed construction of all-carbon quaternary stereocenters via 1,4-addition of arylboronic acids to β-substituted cyclic enones is reported. Reaction of a wide range of arylboronic acids and cyclic enones using a catalyst
Copper-catalyzed asymmetric conjugate addition with chiral SimplePhos ligands
Palais, Laetitia,Alexakis, Alexandre
supporting information; experimental part, p. 10473 - 10485 (2010/05/02)
SimplePhos ligands represent a novel class of monodentate chiral ligands based on a chiral amine moiety and flexible diaryl groups on the phosphorous atom. They can be easily prepared by two different pathways and they can be highly functionalised. Herein we report the copper-catalysed asymmetric conjugate addition of diethyl zinc and trialkylaluminium reagents with SimplePhos ligands, which gives high enantioselectivity with cyclic enones, acyclic enones and nitro-olefins, with up to 98.6 % ee. Of particular interest is the reaction of trialkylaluminium reagents with a wide range of 3substituted enones, thus allowing the formation of stereogenic quaternary carbon centres.
Copper-catalyzed asymmetric conjugate addition of aryl aluminum reagents to trisubstituted enones: Construction of aryl-substituted quaternary centers
Hawner, Christine,Li, Kangying,Cirriez, Virginie,Alexakis, Alexandre
supporting information; experimental part, p. 8211 - 8214 (2009/04/13)
(Chemical Equation Presented) Al be back: Novel aryl and alkenyl aluminum reagents are generated through a halogen/Li exchange-Li/Al transmetalation sequence. These aryl alanes are used in the copper-catalyzed asymmetric conjugate addition reaction to a variety of cyclic enones giving chiral aryl-substituted quaternary centers (see scheme). Both, electron-donating and electron-withdrawing groups give full conversion and very good ee values.
Enantioselective synthesis of all-carbon quaternary stereogenic centers by catalytic asymmetric conjugate additions of alkyl and aryl aluminum reagents to five-, six-, and seven-membered-ring β-substituted cyclic enones
May, Tricia L.,Brown, M. Kevin,Hoveyda, Amir H.
supporting information; experimental part, p. 7358 - 7362 (2009/04/10)
(Chemical Equation Presented) Solution to pesky problems: Effective methods for catalytic asymmetric conjugate additions of alkyl and aryl aluminum reagents with unactivated β-substituted cyclopentenones are now available (see scheme). Transformations, pr
Copper-catalyzed asymmetric conjugate addition of trialkylaluminium reagents to trisubstituted enones: Construction of chiral quaternary centers
Vuagnoux-D'Augustin, Magali,Alexakis, Alexandre
, p. 9647 - 9662 (2008/12/21)
Me3Al, Et1Al, and vinylalane species undergo enantioselective conjugate addition to a wide range of 2- or 3-substituted enones (cyclopent-2enones, cyclohex-2-enones, 3-methyl cyclohept-2-enone) in the presence of catalytic amount of copper salt (copper thiophene carboxylate, [Cu(CH3-CN)4]BF4 or [CuOTf]2· C6H6) and tropos-phosphoramidite-based ligand. Thus, chiral quaternary centers can be built, with up to 98% ee after rigorous optimization of experimental conditions. It was shown that the main important parameter was the order of the introduction of the reagents. Then, the generated enantioenriched aluminium enolates and the chiral conjugate adducts were functionalized and used for subsequent reactions.
