Synthesis of Spirocyclohexadienones via Palladium-Catalyzed Dearomatization of Dibenzoxaborins
作者:Yuyao Zhao、Lincong Sun、Junbiao Chang、Bingxian Liu
DOI:10.1021/acs.orglett.3c04244
日期:2024.2.9
transmetalation from boron to palladium has been achieved, leading to the synthesis of spirocyclohexadienones, an important skeleton demonstrating potential biomedical utility. The [3 + 2] spiroannulation exhibits remarkable regioselectivity and broad substrate scope under mild reaction conditions. This methodology employs dibenzoxaborin as a substrate to establish the formal dearomatization of 2-phenylphenol, which
Looking for a Synergic Effect between NHCs and Chiral P-Ligands
作者:Nicolas Toselli、David Martin、Gérard Buono
DOI:10.1021/ol800225t
日期:2008.4.1
The issue of the added value of NHCs in asymmetric catalysis with respect to trusted chiral P-ligands was addressed: considering a prototypical asymmetric allylic alkylation reaction as a model, the association of a priori inhibiting and achiral NHCs with modular P-ligand resulted in enhancement of er up to 508% and increased rates.
New P-stereogenic triaminophosphines and their derivatives: synthesis, structure, conformational study, and application as chiral ligands
The synthesis, structural, and conformational studies of new P-chiral triaminophosphines, which feature an indolidine and a 1,2,3,4-tetrahydroquinolidine pattern, respectively, are reported. These compounds can feature very different 3D-structures, although they both could be seen a priori as close derivatives of the previously reported 3-phenyl-1,3-diaza-2-phosphabicyclo[3.3.0]octane. The consequences for the use of such compounds and their derivatives in asymmetric metal-catalysis are discussed on the basis of preliminary results in asymmetric cobalt-catalyzed [6+2] cycloaddition. (C) 2010 Elsevier Ltd. All rights reserved.
US5741853A
申请人:——
公开号:US5741853A
公开(公告)日:1998-04-21
Formation and Activation of Zr/Hf Bis(phenolate‐ether) Precatalysts
作者:Eric N. T. Cuthbert、Vincenzo Busico、David E. Herbert、Peter H. M. Budzelaar
DOI:10.1002/ejic.201900716
日期:2019.8.7
Zr and Hf complexes of bis(phenolate‐ether) (“O4”) ligands feature high activity, stereoselectivity and molecular weight capability for propene polymerization at high temperature. Here we report a simplified ligand synthesis and several new examples of O4 ligands. The formation of precatalysts LMR2 (M = Zr, Hf; R = Bn, Me) from LH2 and MR4 was found to be accompanied in some cases by the formation
双(酚盐醚)(“ O4”)配体的Zr和Hf配合物具有高温下丙烯聚合的高活性,立体选择性和分子量能力。在这里,我们报告了简化的配体合成和O4配体的几个新实例。由L H 2和MR 4形成的预催化剂L MR 2(M = Zr,Hf; R = Bn,Me)在某些情况下伴随着二聚物(µ-L)2 [MR 2 ]的形成。2,并且已经确定了两个这样的二聚体的X射线结构。用[Ph 3 C] + [B(C)处理L MMe 26 F 5)4 ] –产生相当干净的阳离子物种L MMe +,通过1 H NMR研究。二维ROESY数据尤其表明,对于“较小”的O4配体,L MMe +阳离子可逆地从活性形式(fac / fac)重新排列为大概无活性的fac / mer或mer / mer形式;更大的取代基似乎抑制了这种重排。讨论了聚合催化的意义。