Isomerization reaction of olefin using RuClH(CO)(PPh3)3

When methyl 5-(tert-butyldiphenylsilyl)oxy-2-pentenoate was refluxed in toluene in the presence of RuCl(CO)(PPh3)(3) (5 mol %), double-bond migration took place to afford methyl 5-(tert-butyldiphenylsilyl)oxy-4-pentenoate in high yield. This means that the double bond conjugated with the ester moiety migrates to a deconjugated position by a ruthenium catalyst. We planned to prepare an enol ether from alpha,beta-unsaturated compounds having an ether moiety in a tether using ruthenium-catalyzed isomerization of the double bond. As a result, silyl or benzyl enol ether was obtained from the alpha,beta-unsaturated ester having alcohol protected by the silyl or benzyl group in a tether in high yield. In this reaction, double bond migration of alpha,beta-unsaturated ketone and alpha,beta-unsaturated amide took place to produce deconjugated compounds. Moreover, the double bond of alpha,beta-unsaturated ester having a triple or double bond in a molecule migrated to produce conjugated enyne and diene. On the other hand, treatment of a bis-metalated compound having an alpha,beta-unsaturated ester moiety or the double bond in a tether with RuClH(CO)(PPh3)(3) gave allyl bis-metalated compound in good yield. These compounds are useful units in synthetic organic chemistry.