Contemporaneous Dual Catalysis: Chemoselective Cross-Coupling of Catalytic Vanadium–Allenoate and π-Allylpalladium Intermediates
作者:Barry M. Trost、Xinjun Luan、Yan Miller
DOI:10.1021/ja204817y
日期:2011.8.17
This paper presents a detailed investigation of a dual catalytic system that combines a vanadium-catalyzed Meyer-Schuster rearrangement and a palladium-catalyzedallylicalkylation. The implementation of this novel reaction relies on matching the formation rates of vanadium-allenoate and π-allylpalladium intermediates with their bimolecular coupling rate in order to minimize the undesired protonation
Acetates of Baylis-Hillman adducts derived from ethyl acrylate, methyl vinyl ketone, and acrylonitrile were coupled with allyltributylstannane using Pd(PPh3)4 or Pd(dba)2 as the catalyst at room temperature to afford the corresponding trisubstituted alka-1,5-dienes in good to high yields.
作者:Marcelle L. Ferguson、Todd D. Senecal、Todd M. Groendyke、Anna K. Mapp
DOI:10.1021/ja058746q
日期:2006.4.1
Allylicphosphoniumylides are readily generated by the combination of an allylic alcohol, a carbene, and a chlorophosphite. Here we demonstrate that these intermediates undergo a thermal [3,3]-rearrangement to provide single isomers of homoallylic phosphonates in good to excellent yields. This new reaction manifold for phosphorus ylides is tolerant of a range of substitution patterns on the reactants
A concise synthesis of alpha-benzylidene-gamma-methyl-gamma-butylolactones 5a-g from substituted benzaldehydes is described. Compounds la-g on reaction with phosphorane 2, provide the pentenoates 3a-g, which can be hydrolyzed to the acids 4a-g. The latter are cyclized to the corresponding butyrolactones 5a-g in excellent yields. The pentenoates 3a-g, on acid catalyzed cyclization, also provide 5a-g in very high yields.