Ruthenium Alkoxycarbene Complexes from an Acetal Function by C−O Bond Cleavage and Alcohol Elimination

Heating solutions of acetal complexes {CpRu(CH 3 CN) 2 [η 1 - P -2-(Ph 2 P)[CH(OR) 2 ]C 6 H 4 ]}OTf ( 3; R = Me, Et) at 60−95 °C results in loss of one CH 3 CN ligand and the alcohol ROH, with concomitant formation of carbene complexes CpRu(CH 3 CN)[η 2 - C,P -2-(Ph 2 P)[C(OR)]C 6 H 4 ]}OTf ( 4 ) in high yield. Kinetic and reactivity studies suggest that the rate-determining step of the conversion of 3 to 4 is oxidative addition of an acetal C−O bond to the ruthenium center, which occurs under neutral, mild conditions.