Both a strong electron donor (IPr) and a strong electron acceptor (P(OPh)3) are necessary for a highly selective, nickel-catalyzed coupling reaction between alkenes, aldehydes, and silyltriflates. Without the phosphite, catalysis is not observed and several side reactions are observed. The phosphite appears to suppress the formation of these byproducts and rescue the catalytic cycle by accelerating reductive elimination from an (IPr–Ni–H)(OTf) complex.
Nickel-Catalyzed Coupling of Alkenes, Aldehydes, and Silyl Triflates
作者:Sze-Sze Ng、Chun-Yu Ho、Timothy F. Jamison
DOI:10.1021/ja062866w
日期:2006.9.1
two recently developed nickel-catalyzed coupling reactions of alkenes, aldehydes, and silyl triflates is presented. These reactions provide either allylic alcohol or homoallylic alcohol derivatives selectively, depending on the ligand employed. These processes are believed to be mechanistically distinct from Lewisacid-catalyzed carbonyl-ene reactions, and several lines of evidence supporting this hypothesis
Bench-Stable <i>N</i>
-Heterocyclic Carbene Nickel Precatalysts for C−C and C−N Bond-Forming Reactions
作者:Felix Strieth-Kalthoff、Ashley R. Longstreet、Jessica M. Weber、Timothy F. Jamison
DOI:10.1002/cctc.201800454
日期:2018.7.9
Herein, we introduce a new class of bench‐stable N‐heterocycliccarbene (NHC) nickel‐precatalysts for homogeneous nickel‐catalysis. The nickel(II) complexes are readily activated to Ni0 in situ under mild conditions, via a proposed Heck‐type mechanism. The precatalysts are shown to facilitate carbonyl‐ene, hydroalkenylation, and amination reactions.
在此,我们介绍了一类新型的实验室稳定的N杂环卡宾 (NHC) 镍预催化剂,用于均相镍催化。通过提出的 Heck 型机制,镍 (II) 配合物在温和条件下很容易原位活化为 Ni 0 。该预催化剂被证明可以促进羰基、加氢烯基化和胺化反应。