Dherbassy Quentin, Schwertz Geoffrey, Chessé Matthieu, Hazra Chinmoy Kumar, Wencel-Delord Joanna, Colobert Françoise
Laboratoire de Chimie Moléculaire (UMR CNRS 7509), Université de Strasbourg, ECPM, 25 Rue Becquerel, 67087, Strasbourg, France.
Chemistry. 2016 Jan 26;22(5):1735-43. doi: 10.1002/chem.201503650. Epub 2015 Dec 18.
Axially chiral biaryls are ubiquitous structural motifs of biologically active molecules and privileged ligands for asymmetric catalysis. Their properties are due to their configurationally stable axis, and therefore, the control of their absolute configuration is essential. Efficient access to atropo-enantioenriched biaryl moieties through asymmetric direct C-H activation, by using enantiopure sulfoxide as both the directing group (DG) and chiral auxiliary, is reported. The stereoselective oxidative Heck reactions are performed in high yields and with excellent atropo-stereoselectivities. The pivotal role of 1,1,1,3,3,3-hexafluoropropanol (HFIP) solvent, which enables a drastic increase in yield and stereoselectivity of this transformation, is evidenced and investigated. Finally, the synthetic usefulness of the herein disclosed transformation is showcased because the traceless character of the sulfoxide DG allows straightforward conversions of the newly accessed, atropopure sulfoxide-biaryls into several differently substituted axially chiral scaffolds.
轴手性联芳基是生物活性分子中普遍存在的结构基序,也是不对称催化中常用的配体。它们的性质归因于其构型稳定的轴,因此,控制其绝对构型至关重要。本文报道了通过使用对映体纯的亚砜作为导向基团(DG)和手性助剂,通过不对称直接C-H活化有效获得轴手性对映体富集的联芳基部分。立体选择性氧化Heck反应以高收率和优异的轴手性立体选择性进行。证明并研究了1,1,1,3,3,3-六氟丙醇(HFIP)溶剂的关键作用,它能显著提高该转化反应的收率和立体选择性。最后,展示了本文所公开转化反应的合成实用性,因为亚砜导向基团的无痕特性使得新获得的轴手性纯亚砜-联芳基能够直接转化为几种不同取代的轴手性支架。