64363-92-4Relevant academic research and scientific papers
CATALYTIC ASYMMETRIC SYNTHESIS OF OPTICALLY ACTIVE α-HALO-CARBONYL COMPOUNDS
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Page/Page column 17, (2010/02/13)
A process for the catalytic asymmetric synthesis of an optically active compound of the formula (la) or (lb): wherein R is an organic group; X is halogen; Rland R2which may the same or different represents H, or an organic group or R
Highly enantioselective direct organocatalytic α-chlorination of ketones
Marigo, Mauro,Bachmann, Stephan,Halland, Nis,Braunton, Alan,Jorgensen, Karl Anker
, p. 5507 - 5510 (2007/10/03)
A C2-symmetric diamine serves as the organocatalyst in an asymmetric α-chlorination reaction of simple ketones (e.g., cyclohexanone, diethyl ketone). Optically active α-chloroketones are formed with excellent enantioselectivities using N-chlorosuccinimide (NCS) as the chlorine source (see scheme). These products have broad synthetic utility, in particular for pharmaceutical applications.
Enantioselective protonation of silyl enol ethers and ketene disilyl acetals with Lewis acid-assisted chiral Bronsted acids: Reaction scope and mechanistic insights
Nakamura, Shingo,Kaneeda, Masanobu,Ishihara, Kazuaki,Yamamoto, Hisashi
, p. 8120 - 8130 (2007/10/03)
Enantioselective protonation is a potent and efficient way to construct chiral carbons. Here we report details of the reaction using Lewis acid-assisted chiral Bronsted acids (chiral LBAs). The 1:1 coordinate complex of tin tetrachloride and optically active binaphthol ((R)- or (S)-BINOL) can directly protonate various silyl enol ethers and ketene disilyl acetals to give the corresponding α-aryl ketones and α-arylcarboxylic acids, respectively, with high enantiomeric excesses (up to 98% ee). A catalytic version of enantioselective protonation has also been achieved using stoichiometric amounts of 2,6-dimethylphenol and catalytic amounts of monomethyl ether of optically active BINOL in the presence of tin tetrachloride. This protonation is also effective for producing α-halocarbonyl compounds (up to 91% ee). DFT calculations on the B3LYP/LANL2DZ level show that the conformational structure of the chiral LBA and the orientation of activated proton on (R)-BINOLs are important for understanding the absolute stereochemistry of the products.
