在温和的反应条件下,简单的卤代酚与α,β-不饱和烯烃成功实现了脱芳构化/螺环化过程。这种转化解决了 SE Ar工艺引起的苯酚支架(6π-电子)脱芳构化转化中的化学选择性问题,从而能够以高产率构建含有连续四元全碳中心的通用环己二烯酮框架。进一步的研究为该过程提供了有价值的见解,揭示了脱溴/螺环化是通过 S RN 1 途径发生的。
Direct Sulfide-Catalyzed Enantioselective Cyclopropanations of Electron-Deficient Dienes and Bromides
作者:Qing-Zhu Li、Xiang Zhang、Rong Zeng、Qing-Song Dai、Yue Liu、Xu-Dong Shen、Hai-Jun Leng、Kai-Chuan Yang、Jun-Long Li
DOI:10.1021/acs.orglett.8b01537
日期:2018.6.15
A catalytic highly regioselective, diastereoselective, and enantioselective cyclopropanation of electron-deficient dienes and bromides via direct sulfide organocatalysis is reported. A variety of vinylcyclopropanes featuring a quaternary chiral center were synthesized in up to 99% yield and up to 98:2 enantiomeric ratio (er). These products could be facilely transformed to various interesting molecules
Phosphine-Catalyzed Annulations of 4,4-Dicyano-2-Methylenebut-3-enoates with Maleimides and Maleic Anhydride
作者:Xiao-Nan Zhang、Gen-Qiang Chen、Xiang-Ying Tang、Yin Wei、Min Shi
DOI:10.1002/anie.201406100
日期:2014.9.26
A novel phosphine‐catalyzed [4+1] annulation of maleimides with 4,4‐dicyano‐2‐methylenebut‐3‐enoates has been developed to afford spirocyclic products, and the maleimides serves as C1 synthons. Moreover, a phosphine‐catalyzed formal [3+2] annulation between 4,4‐dicyano‐2‐methylenebut‐3‐enoates and maleic anhydride has been also achieved, and maleic anhydride behaved as a C3 synthon in the reaction
Regiodivergent construction of medium-sized heterocycles from vinylethylene carbonates and allylidenemalononitriles
作者:Xiang Zhang、Xiang Li、Jun-Long Li、Qi-Wei Wang、Wen-Lin Zou、Yan-Qing Liu、Zhi-Qiang Jia、Fu Peng、Bo Han
DOI:10.1039/c9sc06377c
日期:——
Here we report palladium-catalyzed, regiodivergent [5 + 4] and [5 + 2] annulations of vinylethylene carbonates and allylidenemalononitriles affording over 50 medium-sized heterocycles in high isolated yields with excellent regioselectivities.
Phosphine-catalyzed asymmetric [4+1] annulation of Morita–Baylis–Hillman carbonates with dicyano-2-methylenebut-3-enoates
作者:Xiao-nan Zhang、Hong-Ping Deng、Long Huang、Yin Wei、Min Shi
DOI:10.1039/c2cc34619b
日期:——
asymmetric [4+1] annulation of MBH carbonates with dicyano-2-methylenebut-3-enoates has been developed for the first time, providing an efficient and enantioselectivesynthesis of highlyfunctionalized cyclopentenes bearing one all-carbon quaternarystereogeniccenter.
construction of 4-benzylidene pyrazolones with diverse substitution patterns is a desirable target of organicsynthesis. We developed a (5+1) benzannulation strategy for the practical synthesis of multisubstituted 4-benzylidene pyrazolones, which are challenging to prepare through conventional condensation reactions. This organocatalytic cycloaddition of Morita–Baylis–Hillman carbonate undergoes an unprecedented