A One-Pot Tandem Olefin Isomerization/Metathesis-Coupling (ISOMET) Reaction

A tandem catalytic reaction has been developed as part of a process to discover tungsten-based olefin metathesis catalysts that have a strong preference for terminal olefins over cis or trans internal isomers in olefin metathesis. This tandem isomerization/terminal olefin metathesis reaction (ISOMET) converts C trans internal olefins into C2N-2 cis olefins and ethylene. This reaction is made possible with Ru-based alkene zipper catalysts, which selectively isomerize trans olefins to an equilibrium mixture of trans and terminal olefins, plus tungsten-based metathesis catalysts that react relatively selectively with terminal olefins to give Z Ru cat W cat homocoupled products. The most effective catalysts are W(NAr)(C3H6)(pyr)(OHIPT) (Ar = 2,6-diisopropylphenyl; pyr = pyrrolide; OHIPT = 0-2,6-(2,4,6-i-Pr3C6H2)(2)C6H3) and various [CpRu(P N)(MeCN)]X (X- = [B(3,5-(CF3)(2)C6H3)4]-, PF6-, B(C6F5)(4)-) isomerization catalysts.