Carbonyl Olefination by Means of a gem-Dichloride−Cp₂Ti[P(OEt)₃]₂ System

The preparation of highly substituted olefins by carbonyl olefination using a gem-dichloride−Cp₂Ti[P(OEt)₃]₂ system was studied. The treatment of organotitanium species, formed by reaction with titanocene(II) species from gem-dichlorides having two alkyl substituents, with an aldehyde or ketone afforded tri- or tetrasubstituted olefins in good yields. Acyclic or cyclic trisubstituted vinyl ethers were also obtained by a similar reaction using carboxylic esters or lactones as carbonyl components.