Ketones geminal dialkylation

The above transformation has two different goals 21,22) 1) To increase chemo-, regio-, diastereo- and enantioselectivity in the reaction with carbonyl compounds (Sections C-E), and 2) to make certain reaction types amenable which do proceed readily with classical reagents, e.g., methylation of tertiary alkyl halides, alcohols and ethers, and direct geminal dialkylation of ketones (Section F). It turns out that organotitanium compounds are usually complementary to Li, Mg, Zn, Fe, Ni, Cu and Pd reagents. So far, experience in the above two areas points to the following positive aspects ... 

Geminal Dialkylation of Aldehydes and Ketones 1.532 Alkylative Amination... 

Ethylene dithioacetals of benzophenone and its 4-fluoro-, 4-bromo-, 4,4 -difluoro-, 4,4 -dichlo-ro-, and 3,5-dimethyl-substituted analogs react with sulfuryl chloride or sttlfuryl chloride fluoride in hydrogen fluoride/ pyridine at — 78 C to room temperature to give the corresponding geminal difluorides in 85-90% yield. The reaction is, however, not applicable to dialkyl or alkyl aryl ketones as they undergo chlorination under these conditions.73... 

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