Acyclic reactive terminal olefins

The alkylation of olefinic G-H bonds proceeds when conjugated enones are employed in the ruthenium-catalyzed reaction with alkenes, as shown in Equation (16).1 7 Among the acylcyclohexenes, 1-pivaloyl-l-cyclohexene exhibits a high reactivity and the presence of an oxygen atom at the allylic position in the six-membered ring increases the reactivity of the enones. Some terminal olefins, for example, triethoxyvinylsilane, allyltrimethylsilane, methyl methacrylate, and vinylcyclohexane, are applicable for the alkylation of the olefinic C-H bonds. Acyclic enones also undergo this alkylation. 

Nucleophilic attack on neutral complexes of ii -diene ligands is less common than attack on cationic complexes of these ligands but is known. In one case, Semmelhack reported the reactions of iron complexes of acyclic ii -dienes with reactive carbanions such as LiC-MCjCN and LiCHPhj (Equation 11.47). At -78 °C, the reaction is rapid, and kinetically controlled. Attack occurs at an unsubstituted, internal position to give an unstable o-alkyl Ti -olefin complex. This addition is reversible below 0 °C, and the more stable product is then generated from nucleophilic addition at a terminal position of the diene to give the thermodynamically more stable T -allyl complex. Cyclohexadiene complexes are similarly alkylated by a range of carbanions. ... 

The key to these reactions was the higher rate of reactivity of the cis-olefin relative to the double bonds in the polymer. The predominantly tram stereochemistry of the polymer and the allylic substituents slow the reaction of the polymer double bonds relative to those in the cis acyclic olefin. In subsequent reactions, it was found that the cis-olefin could be present from the hymning of the reaction, that is, the stained norbomene reacted much faster than the cis-olefin. Since the complex resulting from the termination of the polymers with the acyclic... 

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