文摘
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 Cb>nb> trans internal olefins into Cb>2n鈥?b> cis olefins and ethylene. This reaction is made possible with Ru-based 鈥渁lkene zipper鈥?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 homocoupled products. The most effective catalysts are W(NAr)(Cb>3b>Hb>6b>)(pyr)(OHIPT) (Ar = 2,6-diisopropylphenyl; pyr = pyrrolide; OHIPT = O-2,6-(2,4,6-i-Prb>3b>Cb>6b>Hb>2b>)b>2b>Cb>6b>Hb>3b>) and various [CpRu(P鈥揘)(MeCN)]X (X鈥?/sup> = [B(3,5-(CFb>3b>)b>2b>Cb>6b>Hb>3b>)b>4b>]鈥?/sup>, PFb>6b>鈥?/sup>, B(Cb>6b>Fb>5b>)b>4b>鈥?/sup>) isomerization catalysts.<br>Keywords:
tandem catalysis; olefin; metathesis; isomerization; ruthenium; tungsten