Dehydrogenative Formation of a (η⁴-Enone)ruthenium(0) Complex as a Key Intermediate in the Catalytic Isomerization of Allylic Alcohol to Ketone

Abstract

(η 4 -Enone)ruthenium(0) complexes, Ru[η 4 -CH 2 CHC(R) O](PEt 3 ) 3 (R = H ( 3 ), Me ( 4 )), are prepared by the reactions of Ru(η 4 -1,5-COD)(η 6 - 1,3,5-COT) ( 1 )/PEt 3 and Ru(η 4 -1,3,5-COT)(PEt 3 ) 3 ( 2 ) with allylic alcohols such as allyl alcohol and 3-buten-2-ol, respectively. Hydrogen transfer from external allyl alcohol to the coordinated η 4 -3-buten-2-one ligand in 4 leads to the formation of 2-butanone and 3, suggesting the importance of such a (η 4 -enone)ruthenium complex in the ruthenium-catalyzed isomerization of allylic alcohol.