Asymmetric construction of dihydrobenzofuran-2,5-dione derivatives <i>via</i> desymmetrization of <i>p</i>-quinols with azlactones
作者:Lihua Xie、Shunxi Dong、Qian Zhang、Xiaoming Feng、Xiaohua Liu
DOI:10.1039/c8cc08985j
日期:——
3-Amino-benzofuran-2,5-diones containing a chiral amino acid residue were achieved through BG-1·HBPh4 catalyzed enantioselective Michael addition/lactonization cascade reaction of p-quinols with azlactones.
Gem-disubstituted cyclohexadienones and their production
申请人:Ethyl Corporation
公开号:US04804772A1
公开(公告)日:1989-02-14
Quinones may be perfluoroalkylated by means of perfluoroalkyltrihydrocarbyl silane using certain active alkali metal salt catalysts devoid of fluorine (e.g., LiN.sub.3, NaN.sub.3, KN.sub.3, NaCN KCN, CsCN, NaOH, KOH, K.sub.2 CO.sub.3, and Cs.sub.2 CO.sub.3). The reaction--which is conducted under essentially anhydrous conditions, preferably in a suitable liquid phase reaction medium, most preferably a dipolar aprotic solvent--results in the formation of gem-disubstituted cyclohexadienones in which the gem substituents are a perfluoroalkyl group and a trihydrocarbylsiloxy group. These gem-disubstituted compounds in turn can be readily converted to perfluoroalkyl substituted aromatics, thus circumventing the traditional need for photochlorination followed by halogen exchange using hydrogen fluoride as a means of preparing perfluoroalkyl aromatic compounds.
A process which comprises reacting under substantially anhydrous conditions a perfluoroalkyltrihydrocarbylsilane and a carbonyl compound in the presence of a catalyst such that the carbonyl compound is perfluoroalkylated.
Quinones may be perfluoroalkylated by means of perfluoroalkyltrihydrocarbyl silane using trialkylphosphites or hexahydrocarbylphosphorous triamides, or both as catalysts. The reaction --which is conducted under essentially anhydrous conditions, preferably in a suitable liquid phase reaction medium, most preferably a dipolar aprotic solvent--results in the formation of gem-disubstituted cyclohexadienones in which the gem substituents are a perfluoroalkyl group and a trihydrocarbylsiloxy group. These gem-disubstituted compounds in turn can be readily converted to perfluoroalkyl substituted aromatics, thus circumventing the traditional need for photochlorination followed by halogen exchange using hydrogen fluoride as a means of preparing perfluoroalkyl aromatic compounds.
Copper‐Catalyzed Olefination of 4‐CF
<sub>3</sub>
‐Substituted Cyclohexadienones Using Sulfonylmethyl Isocyanides: An Electrostatic Repulsion‐Controlled Regioselectivity Switch Strategy
作者:Seungwon Lee、Mohamed Ahmed Abozeid、Hun Young Kim、Kyungsoo Oh
DOI:10.1002/adsc.202201333
日期:2023.2.21
was shown to exert a pronounced electrostatic repulsion effect to give the olefination products via a preferential [3+2] cycloaddition with the ketone moiety followed by a facile fragmentation of transient oxazoline intermediates. The current Cu(II)-catalyzed olefination of 4-CF3-substituted cyclohexadienones demonstrates the reaction dichotomy involving a CF3-controlled 1,2-addition over a Van Leusen