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A stable and easily prepared catalyst for the enantioselective reduction of ketones. Applications to multistep syntheses
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TLDR
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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Sn/Li Exchange Reactions in 1,ω-Distannylated Conjugated Trienes and Tetraenes: An Enabling Step for Polyene Synthesis
TL;DR: In this article, Navenone B was incorporated into navenone A after Negishi coupling and into (-)-cicutoxin after acylation, and NMR spectroscopy revealed that certain resonances were misassigned previously.
Journal ArticleDOI
Total Synthesis of Kanamienamide.
TL;DR: An efficient and convergent total synthesis of kanamienamide has been developed for the first time, which features a Cu-mediated amide coupling with vinyl iodide at the late stage and key transformations include Evans asymmetric alkylation, CBS asymmetric reduction, ring-closing metathesis reaction, and Stork-Zhao-Wittig olefination.
Journal ArticleDOI
Hexahydropyrrolo[2,3-b]indoles: A New Class of Structurally Rigid Tricyclic Skeleton for Oxazaborolidine-Catalyzed Asymmetric Borane Reduction
TL;DR: In this paper, a new class of structurally rigid tricyclic chiral ligands based on the hexahydropyrrolo[2,3-b]indole skeleton has been rationally designed and the catalytic abilities in asymmetric catalysis have been shown in the enantioselective borane reduction of prochiral ketones to afford the chiral alcohols in excellent yields and high enanti-lectivities.
Journal ArticleDOI
Methods for the synthesis of chiral sulfur heterocycles and their application in the asymmetric Baylis–Hillman reactions
TL;DR: Enantiomerically pure (2S,6S)-2,6-diphenyltetrahydro-2H-thiopyran, (2 S)-2-phenyltetraydro thiophene, and (2 s)-2 S-2 S -phenylate-2 H-THiopyrin were prepared in 70-72% yields and with 86-99% ee via cyclization of corresponding dimesylate in an SN2 cyclization reaction using sodium sulfide nonahydrate.
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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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