- B(C6F5)3-Catalyzed Asymmetric Reductive Amination of Ketones with Ammonia Borane
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The first example of metal-free B(C6F5)3-catalyzed asymmetric reduction amination of ketones with chiral α-methylbenzylamine (α-MBA) using ammonia borane as the reductant is reported. This one-pot method has a broad substrate scope and provides various chiral amines in 81-95% yield with 80-99% de. This protocol was further applied in the total synthesis of cinacalcet.
- Pan, Zhentao,Shen, Leixin,Song, Dingguo,Xie, Zhen,Ling, Fei,Zhong, Weihui
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p. 11502 - 11509
(2018/09/25)
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- Step-efficient access to chiral primary amines
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Routes to enantioenriched amines are outlined that employ reductive amination and carbanion addition methods. The strategies require either one or two reaction steps from prochiral carbonyl compounds for the synthesis of the corresponding chiral primary amines. Georg Thieme Verlag Stuttgart New York.
- Nugent, Thomas C.,Marinova, Sofiya M.
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p. 153 - 166
(2013/02/25)
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- Ytterbium acetate promoted asymmetric reductive amination: Significantly enhanced stereoselectivity
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(Chemical Equation Presented) Reductive amination of prochiral unhindered 2-alkanones 1 with (R)- or (S)-α-MBA in the presence of Yb(OAc) 3 (50-110 mol %), Raney-Ni, and hydrogen (120 psi) results in increased diastereoselectivity for the amine products 2 (80-89% de) with good yield (80-87%). The increased de is based on comparison with the best previously reported de's when using (R)- or (S)-α-MBA, regardless of the strategy employed [stepwise (isolation of ketimines) or one-pot (reductive amination)], reducing agent examined, or achiral Lewis acid or Bronsted acid examined. An in situ cis- to trans-ketimine isomerization mechanism, promoted by Yb(OAc)3, has been proposed to account for the observed increase in diastereoselectivity and suggests a new entry into the control of ketimine geometry.
- Nugent, Thomas C.,El-Shazly, Mohamed,Wakchaure, Vijay N.
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p. 1297 - 1305
(2008/09/17)
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- SYNTHESIS OF AMINES WITH YTTERBIUM LEWIS ACIDS
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The invention relates to methods for producing primary, secondary, and tertiary amines and the corresponding enantiopure or enantioenriched primary or secondary amine products from secondary or tertiary amine diastereomers.
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Page/Page column 24
(2008/06/13)
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- SYNTHESIS OF AMINES WITH CATALYTIC AMOUNTS OF MILD LEWIS ACIDS
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The invention relates to methods for producing primary, secondary and tertiary amines and corresponding enantiopure or enantioenriched primary or secondary amine products, comprising the steps of reductively aminating a ketone, with a nitrogen auxiliary in the presence of a hydrogenating catalyst and a hydrogenating agent, wherein the reductive animation is performed under the influence of a mild Lewis acid, the mild Lewis acid being present at the onset of the reductive amination in at most 25 mol% of the ketone or the nitrogen auxiliary.
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Page/Page column 32
(2008/06/13)
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