Amides Tebbe methylenation

CPv. / Ti Al Tebbe reagent methylenation of aldehydes, ketones, esters, thioesters, amides, carbonates can also induce olefin metathesis in situ preparation [711-713]... 

A drawback of the Tebbe and related reagents is that they are generally suitable only for methylenation and do not permit the formation of higher alkyl analogues. However, the alkenylation of esters (or amides) has been found possible using the Oshima-Lombardo conditions in the presence of TMEDA (tetramethylethylene-diamine) (2.106). This chemistry requires the prior formation of the alkyl gem-dibromide and a more-convenient method, using a dithioacetal, has been reported (2.107). ... 

Carbonyl Olefination with Titanocene-Methylidene and Related Reagents 157 Tab. 4.4. Methylenation of amides, imides, and thiol esters with the Tebbe reagent 3. 

Since esters and amides are much less reactive than aldehydes and ketones towards the Tebbe reagent 3, chemoselective methylenation of dicarbonyl compounds has been achieved, as illustrated in Scheme 4.6 and in the examples in Table 4.2. 

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