The axiallychiral biaryls 2 were obtained in high enantioselectivity by desymmetrization of the σ-symmetric biaryl diacetates 1 by lipase-catalyzed hydrolysis.
<i>t</i>BuLi-Mediated One-Pot Direct Highly Selective Cross-Coupling of Two Distinct Aryl Bromides
作者:Carlos Vila、Sara Cembellín、Valentín Hornillos、Massimo Giannerini、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1002/chem.201502709
日期:2015.10.26
A Pd‐catalyzed direct cross‐coupling of twodistinctarylbromides mediated by tBuLi is described. The use of [Pd‐PEPPSI‐IPr] or [Pd‐PEPPSI‐IPent] as catalyst allows for the efficient one‐pot synthesis of unsymmetrical biaryls at room temperature. The key for this selective cross‐coupling is the use of an ortho‐substituted bromide that undergoes lithium–halogen exchange preferentially.
Reductive Etherification of Aldehydes and Ketones with Alcohols and Triethylsilane Catalysed by Yb(OTf)
<sub>3</sub>
: an Efficient One‐Pot Benzylation of Alcohols
The one‐pot synthesis of symmetrical and unsymmetrical ethers from aldehydes and ketones can be conveniently performed using Yb(OTf)3 as catalyst and triethylsilane as reducing agent in presence of alcohols. This methodology leads to the synthesis of ether derivatives with good yields. Notably, this process resulted a useful tool to protect alcohols as benzyl ether derivatives using differently substituted
Au-Catalyzed Biaryl Coupling To Generate 5- to 9-Membered Rings: Turnover-Limiting Reductive Elimination versus π-Complexation
作者:Tom J. A. Corrie、Liam T. Ball、Christopher A. Russell、Guy C. Lloyd-Jones
DOI:10.1021/jacs.6b10018
日期:2017.1.11
The intramolecular gold-catalyzed arylation of arenes by aryl-trimethylsilanes has been investigated from both mechanistic and preparative aspects. The reaction generates 5- to 9-membered rings, and of the 44 examples studied, 10 include a heteroatom (N, O). Tethering of the arene to the arylsilane provides not only a tool to probe the impact of the conformational flexibility of Ar-Au-Ar intermediates
Robust Chromium Precursors for Catalysis: Isolation and Structure of a Single-Component Ethylene Tetramerization Precatalyst
作者:Nathanael A. Hirscher、Danny Perez Sierra、Theodor Agapie
DOI:10.1021/jacs.9b01387
日期:2019.4.10
We have introduced a new class of stable organometallic Cr reagents (compounds 1-4) that are readily prepared, yet reactive enough to serve as precursors. They were used for ethylene tetramerization catalysis following stoichiometric activation by in situ protonation. This study highlights the importance of balancing stability with reactivity in generating an organometallic precursor that is useful in