zinc bromides and regioconvergent Negishi coupling with aryl or alkenyl triflates. The use of a suitable phosphine ligand favoring Pd migration enabled the selective formation of the linear cross‐coupling product. Subsequently, mixtures of secondary alkyl bromides were prepared from linear alkanes by standard bromination, and regioconvergent cross‐coupling then provided access to the corresponding linear
Addition of carbon nucleophiles to aldehyde tosylhydrazones of aromatic and heteroaromaticcompounds is reported. New observations have been made wherein alkylative reduction is observed in some cases whereas alkylative fragmentation is noticed in others. These findings are exploited in the synthesis of the useful alkaloid piperine and its analogs.
We report nickel-catalyzed cross-coupling of methoxyarenes with alkylmagnesium halides, in which a methoxy group is eliminated. A wide range of alkyl groups, including those bearing β-hydrogens, can be introduced directly at the ipso position of anisole derivatives. We demonstrate that the robustness of a methoxy group allows this alkylation protocol to be used to synthesize elaborate molecules by
我们报告了镍催化的甲氧基芳烃与烷基卤化镁的交叉偶联,其中甲氧基被消除。广泛的烷基,包括那些带有 β-氢的烷基,可以直接在苯甲醚衍生物的 ipso 位置引入。我们证明甲氧基的稳健性允许该烷基化方案通过将其与传统的交叉偶联反应或氧化转化相结合来合成复杂的分子。这种方法的成功取决于使用烷基碘化镁,而不是氯化物或溴化物,这突出了卤化物在使用格氏试剂进行催化反应中的重要性。
Nickel-Catalyzed Borylation of Aryl and Benzyl 2-Pyridyl Ethers: A Method for Converting a Robust <i>ortho</i>
-Directing Group
The nickel‐catalyzed borylation of aryl2‐pyridyl ethers via the loss of a 2‐pyridyloxy group is described. This method allows a 2‐pyridyloxy group to be used as a convertible directing group in C−H bond functionalization reactions. The nickel catalyst can also borylate arylmethyl 2‐pyridyl ethers, in which the stereochemistry at the benzylic position is retained in the case of chiral secondary benzylic
C–F Activation for C(sp<sup>2</sup>)–C(sp<sup>3</sup>) Cross-Coupling by a Secondary Phosphine Oxide (SPO)-Nickel Complex
作者:Valentin Müller、Debasish Ghorai、Lorena Capdevila、Antonis M. Messinis、Xavi Ribas、Lutz Ackermann
DOI:10.1021/acs.orglett.0c02609
日期:2020.9.4
A secondary phosphine oxide (SPO)-nickel catalyst allowed the activation of otherwise inert C–F bonds of unactivated arenes in terms of challenging couplings with primary and secondary alkyl Grignard reagents. The C–F activation is characterized by mild reaction conditions and high levels of branched selectivity. Electron-rich and electron-deficient arenes were suitable electrophiles for this transformation