<i>S</i>-((Phenylsulfonyl)difluoromethyl)thiophenium Salts: Carbon-Selective Electrophilic Difluoromethylation of β-Ketoesters, β-Diketones, and Dicyanoalkylidenes
S‐((Phenylsulfonyl)difluoromethyl)thiopheniumsalts were designed and prepared by a triflic acid catalyzed intramolecular cyclization of ortho‐ethynyl aryldifluoromethyl sulfanes. The thiopheniumsalts were found to be efficient as electrophilic difluoromehtylating reagents for introduction of a CF2H group to sp3‐hybridized carbon nucleophiles such as of β‐ketoesters and dicyanoalkylidenes. The (p
S -((苯磺酰基)二氟甲基)噻吩盐是通过三氟甲磺酸催化邻乙炔基芳基二氟甲基硫烷的分子内环化反应而设计和制备的。发现噻吩盐作为将CF 2 H基团引入sp 3杂交的碳亲核试剂(如β-酮酸酯和二氰基亚烷基)的亲电子二氟甲基化试剂非常有效。的(苯磺酰基)二氟甲基可容易地转化为CF 2温和反应条件下小时。在双(金鸡纳)生物碱的存在下也实现了对映选择性亲电二氟甲基化。
Dual Organocatalysis: Asymmetric Allylic-Allylic Alkylation of α,α-Dicyanoalkenes and Morita-Baylis-Hillman Carbonates
The first highly enantioselective allylic–allylic alkylation of α,α‐dicyanoalkenes and Morita–Baylis–Hillman carbonates by dualcatalysis of (DHQD)2AQN and (S)‐BINOL has been investigated. Excellent stereoselectivities have been achieved for a broad spectrum of substrates (d.r. > 99:1, up to 99 % ee). The multifunctional allylic products could be efficiently converted to a range of complex chiral cyclic
Enantioselective Michael Addition of Dicyanoolefins to α,β-Unsaturated Aldehydes in Aqueous Medium
作者:Jun Lu、Feng Liu、Teck-Peng Loh
DOI:10.1002/adsc.200800145
日期:2008.8.4
A pool of water-compatible catalysts, namely dialkyl-(S)-prolinols, has been developed for the enantioselective directvinylogousMichaeladdition reaction of vinylmalononitriles to α,β-unsaturatedaldehydes in aqueous medium. In many cases, the products can be obtained in almost optically pure form (>96% ee) after a single recrystallization.
Transfer Hydrogenation of Activated CC Bonds Catalyzed by Ruthenium Amido Complexes: Reaction Scope, Limitation, and Enantioselectivity
作者:Dong Xue、Ying-Chun Chen、Xin Cui、Qi-Wei Wang、Jin Zhu、Jin-Gen Deng
DOI:10.1021/jo0478205
日期:2005.4.1
diamine−Ru(II)−(arene) systems was investigated to explore the asymmetric transfer hydrogenation of prochiral α,α-dicyanoolefins. Two parameters had been systematically studied, (i) the structure of the N-sulfonylated chiral diamine ligands, in which several chiral diamines substituted on the benzene ring of DPEN were first reported, and (ii) the structure of the metal precursors, and high enantioselectivitiy (up to
Enantioselective direct vinylogous Michael addition reaction catalyzed by organic molecules
作者:Jun Lu、Feng Liu、Wei-Juan Zhou、Teck-Peng Loh
DOI:10.1016/j.tetlet.2008.07.016
日期:2008.9
Chiral 2-azanorbornyl-3-methanol is used as an organocatalyst for the highly enantioselective directvinylogousMichaeladdition reaction of vinyl malononitriles to α,β-unsaturatedaldehydes. In many cases, the products can be obtained in almost optically pure form (>95% ee) after a single recrystallization.