- Asymmetric Reductive Carbocyclization Using Engineered Ene Reductases
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Ene reductases from the Old Yellow Enzyme (OYE) family reduce the C=C double bond in α,β-unsaturated compounds bearing an electron-withdrawing group, for example, a carbonyl group. This asymmetric reduction has been exploited for biocatalysis. Going beyond its canonical function, we show that members of this enzyme family can also catalyze the formation of C?C bonds. α,β-Unsaturated aldehydes and ketones containing an additional electrophilic group undergo reductive cyclization. Mechanistically, the two-electron-reduced enzyme cofactor FMN delivers a hydride to generate an enolate intermediate, which reacts with the internal electrophile. Single-site replacement of a crucial Tyr residue with a non-protic Phe or Trp favored the cyclization over the natural reduction reaction. The new transformation enabled the enantioselective synthesis of chiral cyclopropanes in up to >99 % ee.
- Heckenbichler, Kathrin,Schweiger, Anna,Brandner, Lea Alexandra,Binter, Alexandra,Toplak, Marina,Macheroux, Peter,Gruber, Karl,Breinbauer, Rolf
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supporting information
p. 7240 - 7244
(2018/06/15)
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- Distal Functional Group Migration for Visible-light Induced Carbo-difluoroalkylation/monofluoroalkylation of Unactivated Alkenes
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A general and practical protocol for elusive carbo-difluoroalkylation/ monofluoroalkylation of unactivated alkenes based on the distal functional group migration is described. A portfolio of functional groups including heteroaryl, imino, formyl, and alkynyl groups showcase the migratory aptitude. In combination with visible-light photocatalysis, a broad range of di- and mono-fluorinated alkyl ketones are readily obtained in synthetically useful yields under mild reaction conditions. (Figure presented.).
- Yu, Jiajia,Wang, Dongping,Xu, Yan,Wu, Zhen,Zhu, Chen
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supporting information
p. 744 - 750
(2017/12/26)
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- A new chiral C1-symmetric NHC-catalyzed addition to α-aryl substituted α,β-disubstituted enals: Enantioselective synthesis of fully functionalized dihydropyranones
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The first enantioselective NHC-catalyzed activation of α-aryl substituted α,β-disubstituted unsaturated aldehyde is successfully developed via a highly-active acyl azolium intermediate. The new C1-symmetric biaryl-saturated imidazolium exhibits a superior ability to enable previously unavailable transformation, and the corresponding fully functionalized dihydropyranones are efficiently synthesized in high yields with excellent enantioselectivities. This journal is
- Lu, Hong,Liu, Jin-Yu,Li, Chen-Guang,Lin, Jun-Bing,Liang, Yong-Min,Xu, Peng-Fei
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supporting information
p. 4473 - 4476
(2015/03/18)
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- A practical method for synthesis of terminal 1,2-diols in high enantiomeric excess via oxazaborolidine-catalyzed asymmetric reduction
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Asymmetric borane reduction of α-hydroxy ketones protected with a tetrahydropyranyl (THP) group catalyzed by Corey's CBS reagent using N- phenylamine-borane complexes as the hydride source provided the corresponding terminal 1,2-diols with a very high enantiomeric excess.
- Cho, Byung Tae,Chun, Yu Sung
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p. 1843 - 1846
(2007/10/03)
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- Synthesis of New Fulvene Derivatives
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Eight new alkyl or aryl pentafulvene derivatives bearing alkyloxy substituents at C6 have been prepared by base-induced condensation of cyclopentadiene with appropriately substituted ketones.All new fulvenes were converted to Diels-Alder cycloaddition pro
- Knight, David B.,Burnette, James C.,Hall, Randall W.,Lambeth, Gregory H.
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p. 184 - 186
(2007/10/02)
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- Induction asymetrique. V. Determination des configurations relatives de γ-amino β-hydroxyesters diastereoisomeres, obtenus par la reaction de Reformatsky
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Addition of various Reformatsky reagents (R1-CHZnBr-CO2CH3) to three aromatic α-aminocetones yields mixtures of threo and erythro diastereomeric γ-amino β-hydroxyesters.The relative configurations of the first terms of eac
- Lucas, Marc,Guette, Jean-Paul
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p. 701 - 720
(2007/10/02)
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