Direct Observation of the Oxidative Addition of the Aryl Carbon−Oxygen Bond to a Ruthenium Complex and Consideration of the Relative Reactivity between Aryl Carbon−Oxygen and Aryl Carbon−Hydrogen Bonds

When RuH2(CO)(PPh3)3 was reacted with 2,2-dimethyl-1-(2-p-tolylphenyl)propan-1-one (2), the ruthenium−aryloxy complex 3 was obtained in 76% yield. The structure of this complex was determined from 1H and 31P NMR and X-ray data. Complex 3 showed the catalytic activity for the coupling of 2 with the phenylboronate 4. The 1H and 31P NMR studies of the reaction of Ru(CO)(PPh3)3 with o-aryloxy pivalophenone revealed that the C−H bond cleavage is a kinetically favorable process but the C−O bond cleavage is a thermodynamic one. The reaction of 2‘-methoxyacetophenone with vinylsilane and organoboronate resulted in chemoselective C−C bond formation.