Grubbs reagents, Tebbe methylenation

Methylenation.1 When heated in THF at 60-65°, this reagent effects methy-lenation of ketones, even readily enolizable ones, in 60-90% yield and of aldehydes (45-60% yield). It also converts esters and lactones into enol ethers, but this reaction is generally slower. It is thus an attractive alternative to the Tebbe and Grubbs reagent. 

Anon. Methylenations with Tebbe-Grubbs reagents. Nachrichten aus Chemie, Technik und Laboratorium 1986, 34, 562-565. 

Grubbs reagents, titanacycles 50 and 51 were prepared by the reaction of Tebbe reagent with a terminal alkene in the presence of a Lewis base. When these complexes are heated, reactive titanocene methylidene 5 is regenerated and will methylenate carbonyl group (49 to 53). ... 

Scheme 3. Carbonyl methylenation with the titanium-methylene species 4 prepared from the Tebbe, Grubbs, or Petasis reagents (1 - 3).

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