- ENANTIOSELECTIVE CONVERSION OF ALDEHYDES TO CYANOHYDRINS BY A CATALYTIC SYSTEM WITH SEPARATE CHIRAL BINDING SITES FOR ALDEHYDE AND CYANIDE COMPONENTS
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A new enantioselective method for the synthesis of chiral cyanohydrins from aldehydes and trimethylsilyl cyanide is described which uses a pair of synergistic chiral reagents, one to activate the aldehyde and the other to provide an equivalent of chiral c
- Corey, E. J.,Wang, Zhe
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- SYNTHESIS OF SMALL MOLECULES INSPIRED BY PHOMOXANTHONE A
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Methods, compositions, and kits are provided for synthesizing bioactive chromane, the method including: constructing a tertiary ether stereocenter enantioselectively by catalyzed alkynylation of a substituted chromenone to obtain a chromanone; reducing alkyne and ketone in the chromanone to obtain a chroman; and converting ester to methyl group thereby obtaining chromane.
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Page/Page column 91-92; 93
(2022/02/28)
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- Copper-Nitrene-Catalyzed Desymmetric Oxaziridination/1,2-Alkyl Rearrangement of 1,3-Diketones toward Bicyclic Lactams
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Although copper-nitrene has been extensively studied as a versatile active species in various transformations, asymmetric reactions involving copper-nitrene have been limited to the aziridination of olefins. Herein, we report the novel copper-nitrene-catalyzed desymmetric oxaziridination reaction of cyclic diketones with alkyl azides and the subsequent rearrangement of the resulting highly active intermediate, which produces a synthetically challenging chiral bicyclic lactam containing a quaternary carbon center. This procedure not only enriches the copper-nitrene-catalyzed asymmetric reactions, but also provides an alternative strategy to address the inherent challenges of catalytic asymmetric Schmidt reactions. This unique reaction could inspire the investigation of novel copper-nitrene-catalyzed asymmetric transformations and their reaction mechanisms.
- Han, Xue,Shan, Li-Xin,Tu, Yong-Qiang,Wang, Hong,Yang, Ming,Zhang, Chang-Sheng,Zhang, Fu-Min,Zhang, Wen-Shuo,Zhang, Xiao-Ming,Zhu, Jin-Xin
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supporting information
p. 22688 - 22692
(2021/09/18)
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- Copper Bis(oxazoline)-Catalyzed Enantioselective Alkynylation of Benzopyrylium Ions
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The stereocontrolled construction of biologically relevant chromanones and tetrahydroxanthones has been achieved through the addition of alkynes to benzopyrylium trilfates under the influence of copper bis(oxazoline) catalysis. Excellent levels of enantiocontrol (63–98 % ee) are achieved in the addition of a variety of alkynes to an array of chromenones with a hydrogen in the 2-position. Promising levels of enantiocontrol (54–67 % ee) are achieved in the alkynylation of chromenones with esters in the 2-position, generating tertiary ether stereocenters resembling those frequently found in naturally occurring metabolites.
- Guan, Yong,Attard, Jonathan W.,Mattson, Anita E.
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supporting information
p. 1742 - 1747
(2020/02/05)
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- Chiral Bis(oxazoline) Ligands as C2-Symmetric Chiral Auxiliaries for the Synthesis of Enantiomerically Pure Bis-Cyclometalated Rhodium(III) Complexes
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The synthesis of enantiomerically pure bis-cyclometalated rhodium(III) complexes using chiral bis(oxazoline) ligands as C2-symmetric chiral auxiliaries is described. Bis(oxazolines) are versatile chiral ligands for asymmetric catalysis but have
- Grell, Yvonne,Demirel, Nemrud,Harms, Klaus,Meggers, Eric
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p. 3852 - 3859
(2019/11/13)
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- Copper-Mediated, Heterogeneous, Enantioselective Intramolecular Buchner Reactions of α-Diazoketones Using Continuous Flow Processing
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Enantioselective intramolecular Buchner reactions of α-diazoketones can be effected using heterogeneous copper-bis(oxazoline) catalysts in batch or using continuous flow processing in up to 83% ee. The catalyst can be reused up to 7 times without loss of activity. For α-diazoketones 3 and 4, the enantioselection achieved in flow with the immobilized catalyst was comparable with the standard homogeneous catalyzed process.
- Crowley, Daniel C.,Lynch, Denis,Maguire, Anita R.
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p. 3794 - 3805
(2018/04/14)
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- Quest for Efficient Catalysts based on Zinc tert-Butyl Peroxides for Asymmetric Epoxidation of Enones: C2- vs C1-Symmetric Auxiliaries
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Zinc tert-butyl peroxide-based catalysts for the asymmetric epoxidation of enones using tert-butyl hydroperoxide as an oxidant have been developed. A comparative study of chiral monoanioninc N,N′-bidentate ligands, C2-symmetric bisoxazolinates and C1-symmetric enaminooxazolinates, revealed excellent performance of C1-symmetric auxiliary ligands on catalytic asymmetric epoxidation of enones (up to 96% yield, 91% ee).
- Raheem Keeri, Abdul,Justyniak, Iwona,Jurczak, Janusz,Lewiński, Janusz
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supporting information
p. 864 - 868
(2016/04/05)
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- C2-Symmetric 4,4',5,5'-Tetrahydrobi(oxazoles) and 4,4',5,5'-Tetrahydro-2,2'-methylenebis as Chiral Ligands for Enantioselective Catalysis
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The synthesis of a series of enantiomerically pure, C2-symmetric 4,4',5,5'-tetrahydro-2,2'-methylene-bis and 4,4',5,5'-tetrahydro-2,2'-bi(oxazoles) is reported.Copper complexes with anionic tetrahydromethylenebis ligands are efficient c
- Mueller, Dieter,Umbricht, Gisela,Weber, Beat,Pfaltz, Andreas
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p. 232 - 240
(2007/10/02)
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- Asymmetric catalytic cyclopropanation of olefins: Bis-oxazoline copper complexes
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Bis-oxazolines (1-7) prepared from diethyl malonate and chiral amino alcohols were converted into their Cu(II) complexes which, upon activation, exhibit high enantioselectivity of up to 99 %ee for catalytic cyclopropanation of olefins.
- Lowenthal, Richard E.,Abiko, Atsushi,Masamune, Satoru
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p. 6005 - 6008
(2007/10/02)
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