Conjugate Addition to Unsaturated Extensions of Electrophillic ultihapto-Complexes

Conjugate Addition to Unsaturated Extensions of Electrophillic M ultihapto-Complexes 

3) A recent paper by Trost ([187]) describes these pathways as direct and Sn2 , but since palladium-catalyzed allylic substitution can be discussed in terms of direct and via the metal ( indirect ) pathways, we pre- 

The (arene)Cr(CO)3 complex is neutral and so is not a very powerful electrophile. In the styrene case, when an ester is placed at the other end of the alkene, Michael addition to the acrylate unit occurs in high yield. Even with a chlorine leaving group on the arene complex (see Section 14.3.5), no local addition was observed [201]. Comparable examples of cationic RuCp complexes with cyanide and thiophenol as the nucleophile give examples where the nucleophile has added to the face of the ligand that carries the metal, and it is proposed that this is the favored kinetic approach [202]. 

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