A novel asymmetric halogenation/semipinacolrearrangement reaction catalyzed by cinchona alkaloid derivatives was developed. Two types of β-haloketones (X = Br, Cl) were obtained with up to 95% yield and 99% enantiomeric excess. The desired (+) and (-) enantiomers of the β-haloketones were readily obtained.
Organocatalytic Asymmetric Fluorination/Semipinacol Rearrangement: An Efficient Approach to Chiral β-Fluoroketones
作者:Zhi-Min Chen、Bin-Miao Yang、Zhi-Hua Chen、Qing-Wei Zhang、Min Wang、Yong-Qiang Tu
DOI:10.1002/chem.201202444
日期:2012.10.8
An asymmetricfluorination/semipinacol rearrangement of 2‐oxa allylic alcohols, as catalyzed by cinchona‐alkaloid derivatives, gives chiral β‐fluoro ketones with moderate to high levels of enantioselectivity (see scheme). Both enantiomers of the product could be obtained by using the appropriate catalyst.