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 (allyl) 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 (PCy (3) ) (3) (+) BPh (4) (-) and Grubbs generation II metathesis catalyst is also described.