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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
Citations
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Asymmetric synthesis of chiral spirocyclanes: Selective formation of 2-acyloxy-1-oxospiro[4.n]alkanes by regio- and stereoselective rearrangement of α,β-epoxy acylates in bicyclo[n.3.0]alkane systems
Hiromichi Fujioka,Shinji Kitagaki,Reiko Imai,M. Kondo,S. Okamoto,Yutaka Yoshida,Shuji Akai,Yasuyuki Kita +7 more
TL;DR: In this paper, the effect of the acyloxy group and stereochemistry of the starting epoxides were studied; the reaction was successfully applied to the synthesis of an optically active chiral spiro compound.
Journal ArticleDOI
Diastereo- and Enantioselective Synthesis of syn-α-Vinylchlorohydrins and cis-Vinylepoxides
TL;DR: Enantioselectivity of reactions of chiral (Z)-(gamma-chloroallyl)boranes with aldehydes are more sensitive to reaction conditions than enantioselectedivity of reacting of other alpha-or gamma-substituted allylboranes.
Journal ArticleDOI
Asymmetric reductions of imines and ketones by chiral oxaborolidines
TL;DR: Asymmetric reduction of imines using dialkoxyborane was studied in this article, which showed moderate (42%) and N -phenylketimine (73%) enantioselectivity.
Journal ArticleDOI
A mechanistically designed mono-cinchona alkaloid is an excellent catalyst for the enantioselective dihydroxylation of olefins
TL;DR: In this paper, a transition state assembly of bis-cinchona alkaloid derivatives was proposed as a promising catalytic ligand for dihydroxylation of olefins.
References
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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.
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