Organotitanium compounds reaction with aldehydes

The organotitanium compounds produced by desulfurization of the diphenyl thioacetals of aldehydes 28 with the titanocene(II) species Cp2Ti[P(OEt)3]2 29 react with carbon—carbon double bonds to form the olefin metathesis-type products. Thioacetals 28 may be transformed into terminal olefins by desulfurization with 29 under an ethene atmosphere (Scheme 14.15) [27]. This reaction is believed to proceed through a titanacyclobutane intermediate, formed by cycloaddition of the titanocene-alkylidene with ethene. 

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]. 

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