Carbonyl Olefination Utilizing a Thioacetal-Titanocene II System

Alkylidenation of Aldehydes, Ketones, and Carboxylic Acid Derivatives 

The carbene complexes thus prepared can be employed for the olefination of a variety of carbonyl compounds. The procedure is operationally simple treatment of the thioacetals with titanocene(II) species at ambient temperature for 5-15 min affords the organotitanium species, which are further treated with ketones and aldehydes in the same reaction vessel to give the olefins or dienes (Table 4.12) [96]. 

Methylenation also proceeds using bis(phenylthio)methane, although the yields of terminal olefins are lower than those obtained by other titanium-based methylenation procedures. 

Alkylidenation with a thioacetal-titanocene(II) system is useful for the conversion of carboxylic acid derivatives into enol ethers, alkenyl sulfides, and enamines. As with other titanium-based reagents, mixtures of stereoisomers are formed in 

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