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。
Heterogeneous Bifunctional Catalytic, Chemo-, Regio- and Enantioselective Cascade Inverse Electron Demand Diels-Alder Reaction
作者:Xianxing Jiang、Hao Zhu、Xiaomei Shi、Yuan Zhong、Yanfeng Li、Rui Wang
DOI:10.1002/adsc.201201038
日期:2013.1.25
We present a bifunctionalcatalytic, chemo-, regio- and enantioselectiveinverseelectrondemandDiels–Alderreaction (IEDDAR) cascade of a variety of methylenebut-3-enoates with azlactones at high levels of yield and enantioselectivity (up to 99% yield, and >99% ee) via a dual HOMOdienophiles and LUMOdienes activated pathway using a heterogeneouscatalytic system. Meanwhile, a novel MNPs-supported
A PPh3 mediated reductive annulation reactionbetweenisatins and 4,4-dicyano-2-methylenebut-3-enoates was developed. The reaction provided an alternative method for constructing five- and three-membered all-carbon spirooxindole compounds. Lithium chloride as a Lewis acid played a key role in the synthesis of spirocyclopentenyl oxindole compounds.
PPh3-catalyzed synthesis of dicyano-2-methylenebut-3-enoates as efficient dienes in catalytic asymmetric inverse-electron-demand Diels–Alder reaction
作者:Xianxing Jiang、Dan Fu、Xiaomei Shi、Shoulei Wang、Rui Wang
DOI:10.1039/c1cc12834e
日期:——
We present here the synthesis of dicyano-2-methylenebut-3-enoates as novel Diels-Alderdienes through an efficient PPh(3)-catalyzed strategy, and an unprecedented PPh(3)-catalyzed addition/all-carbon-based asymmetric inverse-electron-demand Diels-Alder sequence reaction is disclosed for the first time.
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.
A kinetically controllable strategy toward the construction of otherwise challenging nine-memberedcarbocycles is reported. This Pd-catalyzed decarboxylative procedure utilizes vinyl methylene cyclic carbonates as the C5-dipole and allylidenemalononitriles as C4-building blocks. The protocol features user-friendly operations with controllable regioselectivity and generates CO2 as the sole byproduct
报道了一种用于构建具有挑战性的九元碳环的动力学可控策略。这种 Pd 催化的脱羧过程使用乙烯基亚甲基环状碳酸酯作为 C5-偶极子和烯丙基丙二腈作为 C4 结构单元。该协议的特点是用户友好的操作和可控的区域选择性,并产生 CO 2作为唯一的副产物。还研究了合成有价值和热力学有利的七元碳环的形成。