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