(η5-C5Me5)2(Me)Ti-OC(Me)=CH2: titanium enolate or titanium alkoxide?

Article abstract of DOI:10.1016/0022-328X(91)83238-Y

While proton and carbon NMR spectroscopy suggest that (Cp^*)2(Me)Ti-OC(Me)=CH2 (1, Cp^* = η⁵-C5Me5) is a typical O-bound titanium enolate, this material does not exhibit typical enolate reactivity.Specifically, 1 does not react with either methyl iodide or with benzaldehyde.However, some reagents that are typically used in electrophilic attack of metal-alkyl or metal-alkoxide bonds do react with 1.In some cases the electrophile displaces the enolate moiety, while in other cases selectivity for substitution of the titanium-bound methyl group is displayed.Thus the reactivity of 1 is more typical of that expected from a titanium alkoxide or an alkyl titanium rather than a titanium enolate.The possible use of the (Cp^*)2(Me)Ti moiety as a protecting group for ketones is discussed.