<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。
Efficient Multigram Approach to Acetylenes and CF
<sub>3</sub>
‐ynones Starting from Dichloroalkenes Prepared by Catalytic Olefination Reaction (COR)
作者:Vasiliy M. Muzalevskiy、Zoia A. Sizova、Arstan I. Diusenov、Alexey V. Shastin、Valentine G. Nenajdenko
DOI:10.1002/ejoc.202000531
日期:2020.7.23
Efficient two step approach towards terminal acetylenes was elaborated. At the first step, dichloroalkenes were prepared in up to 88 % yields by catalytic olefination reaction COR of arylaldehydes. Treatment of dichloroalkenes with n BuLi effectively led to the corresponding alkynes in up to 97 % yield. A versatile one pot procedure towards CF3‐ynones was elaborated to give these products in up to
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.
A Chiral Naphthyridine Diimine Ligand Enables Nickel‐Catalyzed Asymmetric Alkylidenecyclopropanations
作者:Elena Braconi、Nicolai Cramer
DOI:10.1002/anie.202006082
日期:2020.9.14
A novel class of chiral naphthyridine diimine ligands (NDI*) readily accessible from C2‐symmetric 2,6‐di‐(1‐arylethyl)anilines is described. The utility of these ligands, particularly one with fluorinated aryl side arms, is demonstrated by a reductive Ni‐catalyzed enantioselective alkylidene transfer reaction from 1,1‐dichloroalkenes to olefins. This transformation provides direct access to a broad
synthetic intermediates that possess strain energies exceeding those of saturated cyclopropanes by >10 kcal/mol. This report describes a catalytic reductive methylenecyclopropanation reaction of simple olefins, utilizing 1,1-dichloroalkenes as vinylidene precursors. The reaction is promoted by a dinuclear Ni catalyst, which is proposed to access Ni2(vinylidenoid) intermediates via C—Cl oxidative addition.