<i>C</i><sub>2</sub>-Symmetric Dinickel Catalysts for Enantioselective [4 + 1]-Cycloadditions
作者:Michael J. Behlen、Christopher Uyeda
DOI:10.1021/jacs.0c08262
日期:2020.10.14
methylenecyclopentenes, and the exocyclic alkene is generally obtained with high Z selectivity. E and Z dienes react in a stereoconvergent fashion, providing cycloadducts with the same sense of absolute stereochemistry and nearly identical ee values. This feature allows dienes that are commercially available as E/Z mixtures to be used as substrates for the cycloaddition. A DFT model for the origin of asymmetric
二镍萘啶-双(恶唑啉)催化剂促进亚乙烯基和1,3-二烯的对映选择性分子间[4 + 1]-环加成。该反应的产物是亚甲基环戊烯,通常以高Z选择性获得环外烯烃。E 和 Z 二烯以立体收敛方式反应,提供具有相同绝对立体化学意义和几乎相同 ee 值的环加合物。该特征允许将作为 E/Z 混合物市售的二烯用作环加成的底物。提供了非对称归纳起源的 DFT 模型。
Catalytic [5 + 1]-Cycloadditions of Vinylcyclopropanes and Vinylidenes
作者:Conner M. Farley、Kohei Sasakura、You-Yun Zhou、Vibha V. Kanale、Christopher Uyeda
DOI:10.1021/jacs.0c00356
日期:2020.3.11
1]-cycloaddition between a vinylcyclopropane and a vinylidene to provide methylenecyclohexenes bearing all-meta relationships. Vinylidene equivalents are generated from 1,1-dichloroalkenes using Zn as a stoichiometric reductant. Experimental observations are consistent with a mechanism involving a cobaltacyclobutane formed from a [2 + 2]-cycloaddition between a cobalt vinylidene and a vinylcyclopropane.
Catalytic reductive [4 + 1]-cycloadditions of vinylidenes and dienes
作者:You-Yun Zhou、Christopher Uyeda
DOI:10.1126/science.aau0364
日期:2019.2.22
Five-membered rings for two nickels The Diels-Alder reaction is widely used to make six-membered rings by adding four-carbon dienes to two-carbon alkenes. It would seem straightforward to likewise access five-membered rings from dienes and one-carbon sources, or carbenes, but that does not tend to work. Instead, the carbene adds to just half of the diene to form a cyclopropane. Zhou and Uyeda now show
A dinickel-catalyzed three-component cycloaddition of vinylidenes
作者:Annah E. Kalb、Mingxin Liu、Megan I. Bosso、Christopher Uyeda
DOI:10.1039/d2sc02696a
日期:——
equivalents and a vinylidene. The resulting methylenedioxolane products can be deprotected in one pot under acidic conditions to reveal α-hydroxy ketones. This method provides convenient access to unsymmetrical alkyl-substituted α-hydroxy ketones, which are challenging to synthesize selectively using cross-benzoin reactions. Mechanistic studies are consistent with an initial migratory insertion of the
Palladium-Catalyzed Direct C–H Bond Alkynylations of Heteroarenes Using <i>gem</i>-Dichloroalkenes
作者:Lutz Ackermann、Christoph Kornhaass、Yingjun Zhu
DOI:10.1021/ol300514d
日期:2012.4.6
Palladium-catalyzed direct alkynylations of heteroarenes were accomplished with inexpensive gem-dichloroalkenes as user-friendly electrophiles, which set the stage for a modular, step-economical synthesis of diversely decorated heteroaryl alkynes with ample scope.