Facile Pd(II)- and Ni(II)-Catalyzed Isomerization of Terminal Alkenes into 2-Alkenes

Mono- and 2,2'-disubstituted terminal alkenes can be isomerized into the more stable internal (Z)- and (E)-alkenes by treating them with catalytic amounts of [(allyl)PdCl](2) or [(ally)NiBr](2), a triarylphosphine, and silver triflate at room temperature. The isomeric ratio (E:Z) depends on the alkenes, the E-isomer being the major one. The reaction is tolerant to a wide variety of functional groups including other reactive olefins. Unlike the more reactive Ir catalysts, monosubstituted alkenes give almost exclusively the 2-alkenes. Direct comparison to two of the best-known catalysts for this process ([Ir(PCy3)(3)](+)[BPh4](-) and Grubbs generation II metathesis catalyst) is also described.