Journal ArticleDOI
A stable and easily prepared catalyst for the enantioselective reduction of ketones. Applications to multistep syntheses
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In this paper, the authors described a new method for the catalytic enantioselective reduction of ketones to chiral secondary alcohols, where the stoichiometric reagent in the reduction is borane and the catalyst is a chiral oxazaborolidine such as 1 (0.05-0.1 molfmol of ketone).Abstract:
We have recently described a new method for the catalytic enantioselective reduction of ketones to chiral secondary alcohols.' The stoichiometric reagent in the reduction is borane (usually 0.6 molfmol of ketone), and the catalyst is a chiral oxazaborolidine such as 1 (0.05-0.1 molfmol of ketone). Excellent enantioselectivities, easy recoverability of the chiral catalyst predecessor, near quantitative yields, short reaction times (a few minutes at 23 \"C), and predictability of the absolute configuration of the product contribute to the outstanding utility of this (CBS') process. This paper reports several subsequent developments in this area with respect to improved practicality and important applications. In contrast to 1 which is both air and moisture sensitive, the B-methylated oxazaborolidine 2 can be stored in closed containers at room temperature and weighed or transferred in air. Catalyst 2 is also much more easily prepared than 1. Reaction of (S)-read more
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Journal ArticleDOI
A new chiral catalytic source with an N–PO structural framework containing a proximal hydroxyl group for the borane-mediated asymmetric reduction of prochiral ketones
TL;DR: In this article, octane has been successfully employed as a chiral catalytic source (4 mol %) for borane-mediated asymmetric reduction of prochiral ketones thus providing the resulting secondary alcohols with up to 96% enantiomeric excess.
Journal ArticleDOI
Catalytic Enantioselective Addition of an Allyl Group to Ketones Containing a Tri-, a Di-, or a Monohalomethyl Moiety. Stereochemical Control Based on Distinctive Electronic and Steric Attributes of C-Cl, C-Br, and C-F Bonds.
TL;DR: The approach is scalable and offers an expeditious route to the enantioselective synthesis of versatile and otherwise difficult to access aldehydes that bear an α-halo-substituted quaternary carbon stereogenic center as well as an assortment of 2,2-disubstituting epoxides that contain an easily modifiable alkene.
Journal ArticleDOI
Enantiomeric impurities in chiral catalysts, auxiliaries, and synthons used in enantioselective syntheses. Part 4
TL;DR: The enantiomeric purity of chiral reagents used in asymmetric syntheses directly affects the apparent reaction selectivity and the product's enantiomeic excess as discussed by the authors.
Journal ArticleDOI
Synthetically accessible non-secosteroidal hybrid molecules combining vitamin D receptor agonism and histone deacetylase inhibition.
Joshua Fischer,Tian-Tian Wang,Dainis Kaldre,Natacha Rochel,Dino Moras,John H. White,James L. Gleason +6 more
TL;DR: Remarkably, modeling and X-ray crystallography reveal non-secosteroidal hybrids bind in the VDR ligand binding domain in the opposite orientation of their secosteroidal counterparts.
Journal ArticleDOI
Total Synthesis of Biselyngbyolide B
TL;DR: The first total synthesis of biselyngbyolide B, an 18-membered macrolide, was achieved by esterification using the Shiina reagent and an intramolecular Stille coupling reaction.
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Book
Molybdenum and Molybdenum-Containing Enzymes
TL;DR: In this article, a few moment to read a book even only few pages is recommended, even if it is not obligation and force for everybody, reading book becomes a choice of your different characteristics.
Related Papers (5)
Reduction of Carbonyl Compounds with Chiral Oxazaborolidine Catalysts: A New Paradigm for Enantioselective Catalysis and a Powerful New Synthetic Method.
E. J. Corey,Christopher J. Helal +1 more