Remarkable effect of tris(4-fluorophenyl)phosphine oxide on the stabilization of chiral lanthanum complex catalysts. A new and practical protocol for the highly enantioselective epoxidation of conjugated enonesElectronic supplementary information (ESI) available: HPLC analysis of 2, 1H NMR data for 3 and 4, and crystal data for 5. See http://www.rsc.org/suppdata/ob/b4/b405882h/
作者:Teruaki Mukaiyama、Nobuharu Iwasawa、Rodney W. Stevens、Toru Haga
DOI:10.1016/s0040-4020(01)82423-6
日期:1984.1
A highly diastereoselective cross aldolreaction is developed using divalent tin enolates formed from stannous trifluoromethanesulfonate and carbonyl compounds. The reaction is extended to a highly enantioselective cross aldolreaction employing chiral diamines derivedfrom (S)-proline as ligands.
High-yielding aqueous synthesis of chloroacetophenones and aroyl chlorohydrins
作者:Xixi Zhang、Lei Liu、Chunbao Li
DOI:10.1039/c6ra00433d
日期:——
aroyl chlorohydrins. The reactions were promoted by sulfonyl chlorides and gave quantitative or close to quantitative yields. Notably, chromatographic purification, which is laborious and consumes large amounts of organic solvents, was not needed. These two processes have opened a green and cost-effective channel to prepare the chemical intermediates chloroacetophenones and aroyl chlorohydrins. The
Catalytic asymmetric Darzens reaction promoted by a chiral phase-transfer catalyst derived from cinchonine is described. The desired α,β-epoxy ketones were obtained by use of α-chloro acyclic and cyclic ketones as substrates with moderate to high enantiomeric excesses under mild reaction conditions. This methodology can be quite an effective protocol for practical asymmetric synthesis.
Darzens Reaction Rate Enhancement Using Aqueous Media Leading to a High Level of Kinetically Controlled Diastereoselective Synthesis of Steroidal Epoxyketones
作者:Bo Li、Chunbao Li
DOI:10.1021/jo501500v
日期:2014.9.5
been used in aqueous Darzensreactions. The Darzensreactions were much faster in water than in organic solvents. This aqueous rate enhancement occurred for Darzensreactions between enantiopure steroidal haloketones and aldehydes, yielding enantiopure spiroepoxides with a high level of kinetically controlled diastereoselectivity. Chromatography was avoided in the purifications of the steroidal spiroepoxides
Asymmetric Epoxidation of Enones Promoted by Dinuclear Magnesium Catalyst
作者:Joanna A. Jaszczewska‐Adamczak、Jacek Mlynarski
DOI:10.1002/adsc.202100482
日期:2021.9.7
still a challenging task. In this perspective, we present the application of chiral dinuclear magnesium complexes for asymmetricepoxidation of a broad range of electron-deficient enones. We demonstrate that the in situ generated magnesium-ProPhenol complex affords enantioenriched oxiranes in high yields and with excellent enantioselectivities (up to 99% ee). Our extensive study verifies the literature