Water as a Hydride Source in Palladium-Catalyzed Enantioselective Reductive Heck Reactions
作者:Wangqing Kong、Qian Wang、Jieping Zhu
DOI:10.1002/anie.201700195
日期:2017.3.27
Pd‐catalyzed intramolecular asymmetric carbopalladation of N‐aryl acrylamides followed by reduction of C(sp3)‐Pd intermediate using diboron–water as a hydride source afforded enantioenriched 3,3‐disubstituted oxindoles in high yields and enantioselectivities. When heavy water was used as a deuterium donor in combination with bis(catecholato)diboron (Cat2B2), deuterium was incorporated into the products
N芳基丙烯酰胺在Pd催化下的分子内不对称碳环合钯,然后使用乙硼酸水作为氢化物源还原C(sp 3)-Pd中间体,从而以高收率和对映选择性提供了对映体富集的3,3-二取代的吲哚。当重水与双(邻苯二酚)二硼(Cat 2 B 2)一起用作氘供体时,氘以高合成效率掺入产品中。配体决定了反应的对映选择性和反应路径,从而提供了氢芳基化(还原性Heck)或碳硼化产物。
New Chiral N-Heterocyclic Carbene Ligands in Palladium-Catalyzed α-Arylations of Amides: Conformational Locking through Allylic Strain as a Device for Stereocontrol
作者:Yi-Xia Jia、Dmitry Katayev、Gérald Bernardinelli、Thomas M. Seidel、E. Peter Kündig
DOI:10.1002/chem.201000031
日期:——
Enders/Herrmann‐type chiral N‐heterocyclic carbene (NHC) ligands have been developed and applied in asymmetric palladium‐catalyzed intramolecular α‐arylations of amides. The best ligands feature the bulky tert‐butyl group and ortho‐substituted aryl groups at the stereogenic centers. Aryl bromides readily react at room temperature and aryl chlorides at 50 °C. The highly enantiomerically enriched (up
Synthesis of 3,3-Disubstituted Oxindoles by Palladium-Catalyzed Asymmetric Intramolecular α-Arylation of Amides: Reaction Development and Mechanistic Studies
作者:Dmitry Katayev、Yi-Xia Jia、Akhilesh K. Sharma、Dipshikha Banerjee、Céline Besnard、Raghavan B. Sunoj、E. Peter Kündig
DOI:10.1002/chem.201301572
日期:2013.9.2
their performance is compared. One of them, L8, containing a tBu and a 1‐naphthyl group at the stereogenic centre, proved superior and was very efficient in the asymmetric synthesis of fifteen new spiro‐oxindoles and three azaspiro‐oxindoles often in high yields (up to 99 %) and enantioselectivities (up to 97 % ee; ee=enantiomeric excess). Three palladacycle intermediates resulting from the oxidative addition
掺有手性N-杂环卡宾(NHC)配体的钯配合物催化酰胺的不对称分子内α-芳基化反应,生成3,3-二取代的羟吲哚。已经进行了全面的DFT研究,以深入了解这种转变的机制。氧化添加被证明是决定速率的,还原消除是对映选择性的决定。详细介绍了七个新的NHC配体的合成,并比较了它们的性能。其中之一,L8,在立体异构中心含有一个t Bu和一个1-萘基,被证明是优越的,并且在不对称合成15个新的螺-氧杂吲哚和3个氮杂-螺氧杂吲哚中通常非常高的收率(高达99) %)和对映选择性(高达97% ee; ee =对映体过量)。分离并氧化了[Pd(NHC)]到芳基卤化物键中形成的三种palladacycle中间体,并对其结构进行了表征(X射线)。使用这些中间体作为催化剂,表明烯烃添加剂在增加周转次数和频率中起着重要的作用。