Chiral Hydroxytetraphenylene-Catalyzed Asymmetric Conjugate Addition of Boronic Acids to Enones
作者:Guo-Li Chai、A-Qiang Sun、Dong Zhai、Juan Wang、Wei-Qiao Deng、Henry N. C. Wong、Junbiao Chang
DOI:10.1021/acs.orglett.9b01637
日期:2019.7.5
(S)-2,15-Br2-DHTP-catalyzed asymmetric conjugate addition of boronic acids to β-trifluoromethyl α,β-unsaturated ketones and enones was studied. The reaction afforded the corresponding Michael addition products in moderate to high yields with excellent enantioselectivities (up to 99:1 er). This catalytic system features mild reaction conditions, high efficiency, and tolerance to heteroarylboronic acids
Rhodium(III)-catalyzed conjugate addition of aromatic and olefinic C-H bonds to CF3-substituted unsaturated ketones was efficiently achieved. Both arene and olefin substrates bearing a chelate assisted-directing group were coupled with a...
Rh(III)-Catalyzed Annulation of 2-Biphenylboronic Acid with Diverse Activated Alkenes
作者:Bingxian Liu、Lingyun Yang、Zhenzhen Dong、Junbiao Chang、Xingwei Li
DOI:10.1021/acs.orglett.1c02597
日期:2021.9.17
the reductive elimination process prior to protonolysis, affording the [4 + 2] annulated products instead of the simple 1,4-addition product. Seven-membered rings were obtained when disubstituted cyclopropenones were employed. Bridged cycles were isolated from the coupling of 2-biphenylboronic acid with benzoquinones as a result of 2-fold Michaeladditions. The substrate scopes were found to be broad
Process for producing 4,4,4,- trifluoro-3-hydroxybutyric acid
申请人:CENTRAL GLASS COMPANY, LIMITED
公开号:US20030088095A1
公开(公告)日:2003-05-08
A first process for producing an optically active perfluoroalkylcarbinol derivative includes (a) reacting an optically active imine with a compound that is a hemiacetal of a perfluoroalkylaldehyde or a hydrate of a perfluoroalkylaldehyde to obtain a condensate; and (b) hydrolyzing the condensate under an acid condition. A second process for increasing optical purity of an optically active 4,4,4-trifluoro 3-hydroxy-1-aryl-1-butanone derivative includes (a) precipitating a racemic crystal of the derivative, from the derivative; and (b) removing the racemic crystal from the derivative. A third process for increasing optical purity of the butanone derivative includes recrystallizing the derivative. Novel compounds are optically active and inactive 4,4,4-trifluoro-3-hydroxybutanoic aryl ester derivatives. A fourth process for producing an optically active or optically inactive 4,4,4-trifluoro-3-hydroxybutyric acid aryl ester derivative includes oxidizing an optically active or optically inactive 4,4,4-trifluoro-3-hydroxy-1-aryl-1-butanone derivative. A fifth process for increasing optical purity of the optically active aryl ester derivative includes recrystallizing the derivative. A sixth process for producing an optically active 4,4,4-trifluoro-1,3-butanediol includes reducing the optically active aryl ester derivative by a hydride. A seventh process for producing an optically active or inactive 4,4,4-trifluoro-3-hydroxybutyric acid alkyl ester derivative includes reacting under an acid condition the optically active or optically inactive aryl ester derivative with a lower alcohol. It is possible to suitably combine at least two of the first to seventh processes.
The reaction of trifluoroacetaldehyde ethyl hemiacetal or hydrate with an equimolar amount of imine in hexane at reflux temperature for 1 h gave the corresponding β-hydroxy-β-trifluoromethyl ketones in good to excellent yields.