Photocatalytic Giese Addition of 1,4-Dihydroquinoxalin-2-ones to Electron-Poor Alkenes Using Visible Light
作者:Jaume Rostoll-Berenguer、Gonzalo Blay、José R. Pedro、Carlos Vila
DOI:10.1021/acs.orglett.0c02953
日期:2020.10.16
The optimized reaction conditions provide a good yield for the radical conjugate addition products (44 examples) with a wide range of structurally different Michael acceptors. A gram scale reaction using sunlight irradiation is also described. Furthermore, several transformations were carried out with the Giese addition products.
使用Ru(bpy)3 Cl 2作为光催化剂和(PhO)2 PO 2 H作为添加剂,实现了1,4-二氢喹喔啉-2-酮与Michael受体的可见光光氧化还原催化偶联。优化的反应条件为具有广泛结构上不同的迈克尔受体的自由基共轭加成产物(44个实例)提供了良好的收率。还描述了使用阳光照射的克级反应。此外,使用Giese添加产品进行了几次转化。
Enantioselective Stetter Reactions of Enals and Modified Chalcones Catalyzed by N-Heterocyclic Carbenes
作者:Xinqiang Fang、Xingkuan Chen、Hui Lv、Yonggui Robin Chi
DOI:10.1002/anie.201105812
日期:2011.12.2
New trick for an old cat.: Triazolium‐based N‐heterocycliccarbenes (NHCs) catalyze the selective generation of acyl anion equivalents for the title reaction. The stereoelectronic properties of the enal‐derived Breslow intermediates and the unique reactivity of the modified chalcones are crucial for the Stetter reactions to occur. EWG=electron‐ withdrawing group.
β-Functionalization of Carboxylic Anhydrides with β-Alkyl Substituents through Carbene Organocatalysis
作者:Zhichao Jin、Shaojin Chen、Yuhuang Wang、Pengcheng Zheng、Song Yang、Yonggui Robin Chi
DOI:10.1002/anie.201408604
日期:2014.12.1
The first NHC‐catalyzed functionalization of carboxylicanhydrides is described. In this reaction, the β carbon behaves as a nucleophilic carbon and undergoes asymmetric reactions with electrophiles. Anhydrides with challenging β‐alkyl substituents work effectively.
Enantioselective Diels–Alder Reactions of Enals and Alkylidene Diketones Catalyzed by N-Heterocyclic Carbenes
作者:Xinqiang Fang、Xingkuan Chen、Yonggui Robin Chi
DOI:10.1021/ol201917u
日期:2011.9.2
introduced to the α-position of chalcones, and the resulting alkylidene diketones showed new reactivities with enals under the catalysis of N-heterocycliccarbenes (NHCs). Selective activation of enals affords enolate equivalents that undergo highly enantioselective intermolecular Diels–Alder reactions with the alkylidene diketones. No products that might have resulted from typical homoenolate pathways were
Unprecedented Direct Oxygen Atom Transfer from Hypervalent Oxido-λ<sup>3</sup>-iodanes to α,β-Unsaturated Carbonyl Compounds: Synthesis of α,β-Epoxy Carbonyl Compounds
Tetra-n-butylammonium oxido-lambda(3)-iodane, prepared from 1-hydroxy-1,2-benziodoxol-3(1H)-one by reaction with tetra-n-butylammonium fluoride, directly undergoes oxygenatom transfer to alpha,beta-unsaturated carbonylcompounds, yielding epoxides.