Journal ArticleDOI
Enantioselective Fluorination Mediated by Cinchona Alkaloid Derivatives/Selectfluor Combinations: Reaction Scope and Structural Information for N-Fluorocinchona Alkaloids
TLDR
X-ray crystallography and 1H NMR analyses of the cinchona alkaloids/Selectfluor combination have established that the species that mediate this novel reaction are N-fluoroammonium cinchonia alkaloid tetrafluoroborates, which adopt open conformations.Abstract:
Cinchona-alkaloid/Selectfluor combinations efficiently fluorinate a variety of carbonyl compounds in a highly enantioselective manner to furnish chiral alpha-fluorocarbonyl compounds. The DHQB/Selectfluor combination is effective for the enantioselective fluorination of indanones and tetralones 1 in up to 91% ee. The first enantioselective syntheses of chiral derivatizing reagents 3 was accomplished with high ee and in high chemical yields by the DHQDA/Selectfluor combination. 3-Fluorooxindoles 7 were prepared with ee up to 83% using the (DHQ)2AQN/Selectfluor or the (DHQD)2PYR/Selectfluor combination. Since the combinations are conveniently prepared in situ from readily available reagents, the present system represents a practical method for enantioselective fluorination. X-ray crystallography and 1H NMR analyses of the cinchona alkaloids/Selectfluor combination have established that the species that mediate this novel reaction are N-fluoroammonium cinchona alkaloid tetrafluoroborates, which adopt open conformations.read more
Citations
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Journal ArticleDOI
Introduction of Fluorine and Fluorine-Containing Functional Groups
TL;DR: This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.
Journal ArticleDOI
Asymmetric fluorination, trifluoromethylation, and perfluoroalkylation reactions.
Jun-An Ma,Dominique Cahard +1 more
Journal ArticleDOI
Update 1 of: Asymmetric Fluorination, Trifluoromethylation, and Perfluoroalkylation Reactions
Jun-An Ma,Dominique Cahard +1 more
Journal ArticleDOI
Recent advances in organocatalytic methods for the synthesis of disubstituted 2- and 3-indolinones
TL;DR: This review aims to cover the literature on asymmetric quaternary carbons, 2-substituted and 2,2'-disubtituted 3-indolinones, from its origin to the end of 2011.
Journal ArticleDOI
Selectfluor: mechanistic insight and applications.
TL;DR: The many applications of selectfluor are documented and possible mechanistic pathways for its reaction are discussed and this reagent is described as one of the most reactive electrophilic fluorinating reagents available, but it is also safe, nontoxic, and easy to handle.
References
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Edmond Differding,Robert W. Lang +1 more
TL;DR: In this article, optically pure N-fluoro sultams (−)-3 and (+)-5 are shown to have enantioselective fluorinating reagents and unprecedented enantiomeric excesses up to 70% are observed when various prochiral metal enolates are fluorinated by using these new reagents.
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An ENDOR study of the tyrosyl free radical in ribonucleotide reductase from Escherichia coli
Christopher J. Bender,Margareta Sahlin,Gerald T. Babcock,Bridgette A. Barry,Tavarekere K. Chandrashekar,Scott P. Salowe,JoAnne Stubbe,Bjoern Lindstroem,Leif Petersson +8 more
TL;DR: In this paper, an analysis of the principal tensor components of the ortho protons (A x = −26.9 MHz, A y = −7.8 MHz and A z = −19.7 MHz) and the strongly coupled β-methylene proton was performed to characterize the enzyme-bound radical.
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Preparation and properties of chiral fluoroorganic compounds
Journal ArticleDOI
.alpha.,.alpha.-Difluoroarylacetic acids: preparation from (diethylamino)sulfur trifluoride and .alpha.-oxoarylacetates
W. J. Middleton,E. M. Bingham +1 more
Journal ArticleDOI
A novel and efficient synthesis of 3-fluorooxindoles from indoles mediated by Selectfluor.
TL;DR: Treatment of several 3-substituted indoles, including derivatives of tryptophan and serotonin, with commercially available Selectfluor in acetonitrile/water furnished 3- submerged indoles obtained are sterically similar to both oxindoles and 3-hydroxyoxindoles, and should be useful as probes for investigating the enzymatic mechanism of indole biosynthesis and metabolism.