Asymmetric Epoxidation Using Iminium Salt Organocatalysts Featuring Dynamically Controlled Atropoisomerism
作者:Philip C. Bulman Page、Christopher J. Bartlett、Yohan Chan、David Day、Phillip Parker、Benjamin R. Buckley、Geracimos A. Rassias、Alexandra M. Z. Slawin、Steven M. Allin、Jérôme Lacour、André Pinto
DOI:10.1021/jo300915u
日期:2012.7.20
Introduction of a pseudoaxial substituent at a stereogenic center adjacent to the nitrogen atom in binaphthyl- and biphenyl-derived azepinium saltorganocatalysts affords improved enantioselectivities and yields in the epoxidation of unfunctionalized alkenes. In the biphenyl-derived catalysts, the atropoisomerism at the biphenyl axis is controlled by the interaction of this substituent with the chiral
An Efficient Catalytic Asymmetric Epoxidation Method
作者:Zhi-Xian Wang、Yong Tu、Michael Frohn、Jian-Rong Zhang、Yian Shi
DOI:10.1021/ja972272g
日期:1997.11.1
This article describes a highly effective catalyticasymmetricepoxidation method for olefins using potassium peroxomonosulfate (Oxone, Dupont) as oxidant and a fructose-derived ketone (1) as catalyst. High enantioselectivies have been obtained for trans-disubstituted and trisubstituted olefins which can bear functional groups such as tributylsilyl ether, acetal, chloride, and ester. The enantiomeric
An efficient ketone-catalyzed asymmetric epoxidation using hydrogen peroxide (H 2 O 2 ) as primary oxidant
作者:Lianhe Shu、Yian Shi
DOI:10.1016/s0040-4020(01)00362-3
日期:2001.6
High enantioselectivities have been obtained for asymmetricepoxidation of olefins using a fructose-derived chiral ketone (5) as catalyst and hydrogenperoxide as primary oxidant.
Chiral ketone-catalyzed asymmetric epoxidation of olefins with Oxone®
作者:Koichiro Matsumoto、Kiyoshi Tomioka
DOI:10.1016/s0040-4039(01)02204-3
日期:2002.1
Chiral ketones 1 and 2 bearing 1-aza-7-oxabicyclo[3.5.0]decane skeleton and their C2-symmetric analogue 3 were readily prepared and evaluated as a chiral dioxirane precursor for asymmetricepoxidation of olefins with Oxone®. The ketone 2, bearing a diphenyl steric wall, was not effective and gave quite poor selectivity. Good selectivity up to 83% ee was obtained using 1 and 3, which suggested that
New Chiral Iminium Salt Catalysts for Asymmetric Epoxidation
作者:Philip C. Bulman Page、Benjamin R. Buckley、Gerasimos A. Rassias、A. John Blacker
DOI:10.1002/ejoc.200500756
日期:2006.2
range of enantiomerically pure 4-substituted 5-amino-1,3dioxanes has been condensed with 2-(2-bromoethyl)benzaldehyde to produce chiral dihydroisoquinolinium salts, which are effective asymmetriccatalysts for the epoxidation of simple alkenes, giving ees of up to 71 %. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006).