CH Activation Reactions of Ruthenium N-HeterocyclicCarbene Complexes: Application in a Catalytic TandemReaction Involving CC Bond Formation from Alcohols
A series of ruthenium hydride N-alkyl heterocyclic carbene complexes has been investigated ascatalysts for a tandem oxidation/Wittig/reduction reaction to give CC bonds from alcohols. The CH-activated carbene complex Ru(IiPr2Me2)‘(PPh3)2(CO)H (9) proves to be the most active precursor catalyzingthe reaction of PhCH2OH and Ph3PCHCN in 3 h at 70 °C. These results provide (a) a rare case in whichN-alkyl carbenes afford higher catalytic activity than their N-aryl counterparts and (b) a novel example ofthe importance of NHC CH activation in a catalytic cycle.
