Aldehyde olefination with a ruthenium(II) salen catalyst

A ruthenium salen complex of the type Ru(II)(salen)(PPh3)2 can be successfully applied as catalyst for the olefination of a broad variety of aldehydes. Dependent on the electron richness of the applied aldehydes, good to very good olefin yields are obtained and high E/Z-selectivities are reached at 80 °C reaction temperature with ethyl diazo acetate being the reaction partner. The reaction rate depends on the electron-donor capabilities of the aldehydes. Electron-poor aldehydes undergo faster reactions than electron-rich aldehydes, but both electron-rich and bulky aldehydes can be transformed to olefins in very good yields as well. Very good E/Z-selectivities and quantitative olefin yields are obtained for aromatic aldehydes when the reaction is performed in the room-temperature ionic liquid (Bmim)PF6 and toluene.