Murai reaction

While not the first example of C-H activation, the Murai reaction is notable for its high efficiency and scope.

[6] Bidentate directing groups allow ortho alkylation of aromatic rings with α,β-unsaturated ketones, which typically are unreactive in Murai reactions.

[8] The reaction preferentially adds at the least sterically hindered ortho position, except when there is a meta group capable of coordinating with the Ru catalyst.

[9] The catalytic cycle is proposed to begin with coordination of the ketone followed by oxidative addition of a C-H bond.

As in the Ru0 proposed mechanism, this agostic interaction leads to the oxidative addition of the ortho C-H. Reductive elimination releases H2, which remains coordinated, giving complex 3.

Murai reaction; X = directing group .
Effect of m-substituents on regioselectivity. Percentages are isolated yields of substitution at the indicated position.
Proposed mechanism for the reaction of ethene and acetophenone (L = PR 3 ). Some spectator ligands on Ru are omitted.
Mechanism proposed for the reaction acetophenone and ethylene as catalyzed by [Ru(H) 2 (H 2 ) 2 (PR 3 ) 2 ]. Spectator ligands ( PMe 3 ) omitted for clarity.