- The Cyclohexa-2,5-dienyl Group as a Placeholder for Hydrogen: Organocatalytic Michael Addition of an Acetaldehyde Surrogate
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An aldehyde with a cyclohexa-2,5-dienyl group in the α-position is introduced as a storable surrogate of highly reactive acetaldehyde. The cyclohexa-2,5-dienyl unit is compatible with an enantioselective Michael addition to nitroalkenes promoted by a Haya
- Chen, Weiqiang,Fang, Huaquan,Xie, Kaixue,Oestreich, Martin
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p. 15126 - 15129
(2020/10/23)
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- Asymmetric Redox-Annulation of Cyclic Amines
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Cyclic amines such as 1,2,3,4-tetrahydroisoquinoline undergo regiodivergent annulation reactions with 4-nitrobutyraldehydes. These redox-neutral transformations enable the asymmetric synthesis of highly substituted polycyclic ring systems in just two steps from commercial materials. The utility of this process is illustrated in a rapid synthesis of (-)-protoemetinol. Computational studies provide mechanistic insights and implicate the elimination of acetic acid from an ammonium nitronate intermediate as the rate-determining step.
- Kang, YoungKu,Chen, Weijie,Breugst, Martin,Seidel, Daniel
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p. 9628 - 9640
(2015/10/12)
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- Remote sulfonamido group enhances reactivity and selectivity for asymmetric michael addition of nitroalkanes to α,β-unsaturated aldehydes
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The pyrrolidine-camphorsulfonamide-based catalyst 1 a catalyzes the enantioselective conjugate addition of nitroalkanes to α,β- unsaturated aldehydes in the presence of five equivalents of water in iPrOH to give the corresponding chiral Michael adducts in good yields and high enantioselectivities (up to 99 % ee) with a catalyst loading as low as 1 mol%.
- Huang, Yu-Chao,Uang, Biing-Jiun
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supporting information
p. 2444 - 2448
(2014/11/07)
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- Organocatalyst-mediated dehydrogenation of aldehydes to α,β-unsaturated aldehydes, and oxidative and enantioselective reaction of aldehydes and nitromethane catalyzed by diphenylprolinol silyl ether
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A one-pot transformation of aldehydes into α,β-unsaturated aldehydes was developed using both N-benzyl-N-methylamine and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as catalysts and MnO2 as a terminal oxidant. An oxidative and enantioselective reaction of aldehydes and nitromethane was established using both diphenylprolinol silyl ether and DDQ as a catalyst with MnO2 as a terminal oxidant, in which synthetically important β-substituted γ-nitro aldehydes were obtained with excellent enantioselectivity. Copyright
- Hayashi, Yujiro,Itoh, Takahiko,Ishikawa, Hayato
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supporting information
p. 3661 - 3669
(2014/01/06)
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- Asymmetric synthesis of γ-nitroesters by an organocatalytic one-pot strategy
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An enantioselective synthesis of γ-nitroesters by a one-pot asymmetric Michael addition/oxidative esterification of α,β- unsaturated aldehydes is presented. The procedure is based on merging the enantioselective organocatalytic nitroalkane addition with an N-bromosuccinimide-based oxidation. The γ-nitroesters are obtained in good yields and enantioselectivities, and the method provides an attractive entry to optically active γ-aminoesters, 2-piperidones, and 2-pyrrolidones.
- Jensen, Kim L.,Poulsen, Pernille H.,Donslund, Bjarke S.,Morana, Fabio,Jorgensen, Karl Anker
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supporting information; experimental part
p. 1516 - 1519
(2012/06/05)
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- Oxidative and enantioselective cross-coupling of aldehydes and nitromethane catalyzed by diphenylprolinol silyl ether
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Synthetically important β-substituted γ-nitro aldehydes have been synthesized with excellent enantioselectivity by the cross-coupling reaction of β-aryl substituted aldehydes or Y γ-unsaturated aldehydes and nitromethane using 2,3-dichloro-5,6-dicyanoquinone (DDQ) and diphenylprolinol silyl ether as an oxidant and catalyst, respectively (see scheme; TMS=trimethylsilyl).
- Hayashi, Yujiro,Itoh, Takahiko,Ishikawa, Hayato
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supporting information; experimental part
p. 3920 - 3924
(2011/05/15)
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- Chiral ionic liquids bearing O-silylated α,α-diphenyl (S)- Or (R)-prolinol units: Recoverable organocatalysts for asymmetric michael addition of nitroalkanes to α,β-enals
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Chiral ionic liquids bearing O-silylated α,α-diphenyl (S)- or (R)-prolinol units tagged to the imidazolium cation were synthesized and their activity as catalysts in the Michael addition of nitroalkanes to α,β-unsaturated aldehydes was evaluated. Respective (S) or (R) adducts were obtained in the reactions in high yields (up to 95 %) and with high enantio-selectivity (up to 99% ee). Remarkably, the immobilized orgariocatalysts could be used five times without any decrease in product: yields or ee values. (R)-Michael adducts could be easily transformed into the most active (R) enantiomers of medications Phenibut, Baclofen, and Rolipram for the treatment of CNS disorders.
- Maltsev, Oleg V.,Kucherenko, Alexandr S.,Beletskaya, Irina P.,Tartakovsky, Vladimir A.,Zlotin, Sergei G.
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supporting information; experimental part
p. 2927 - 2933
(2010/08/07)
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- Highly active water-soluble and recyclable organocatalyst for the asymmetric 1,4-conjugate addition of nitroalkanes to α,β-unsaturated aldehydes
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A novel strategy for the catalytic asymmetric conjugate addition of nitroalkanes to α,β-unsaturated aldehydes in aqueous media has been developed by using diarylprolinol silyl ether in combination with benzoic acid as a water-soluble organocatalyst provid
- Ghosh, Subrata K.,Zheng, Zilong,Ni, Bukuo
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supporting information; experimental part
p. 2378 - 2382
(2010/12/25)
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- Asymmetric Michael reaction of acetaldehyde catalyzed by diphenylprolinol silyl ether
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(Chemical Equation Presented) An acetaldehyde breakthrough: The catalytic asymmetric Michael addition reaction of acetaldehyde and various nitroalkenes in the presence of a chiral diphenylprolinol silyl ether organocatalyst is described (see scheme; TMS =
- Hayashi, Yujiro,Itoh, Takahiko,Ohkubo, Masahiro,Ishikawa, Hayato
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supporting information; experimental part
p. 4722 - 4724
(2009/02/06)
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- Catalytic asymmetric michael reactions of acetaldehyde
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(Chemical Equation Presented) Acetaldehyde, now a big contender: A silyl prolinol derivative was found to catalyze the first Michael addition of acetaldehyde with both aromatic and aliphatic nitroolefins in excellent enantioselectivities (see scheme, TMS = trimethylsilyl). The utility of the reaction is illustrated in the synthesis of three current pharmaceuticals and in the synthesis of an enantiopure 3-monosubstituted pyrrolidine.
- Garcia-Garcia, Patricia,Ladepeche, Arnaud,Halder, Rajkumar,List, Benjamin
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supporting information; scheme or table
p. 4719 - 4721
(2009/02/06)
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