Olefination [C-C Bond Formation]

　Carbonyl olefination is one of the most fundamental conversions in organic synthesis and a variety of synthetic methods have been developed. Particularly, synthetic methods focused on the chemical properties of heavy-atoms such as phosphorus, silicon and sulfur atoms had long been studied. One of them, the Wittig reaction is the representative carbonyl olefination reaction. Other similar reactions, the silicon-mediated Peterson olefination and two sulfur-based “Julia” carbonyl olefinations named the Julia-Lythgoe olefination and the Julia‐Kocienski olefination are also useful olefinating methods. Among them, as the Wittig and Horner-Emmons reactions are the most general carbonyl olefinations, a number of improved synthetic applications have also been investigated. Some of them allow providing easer work-up procedures and increasing the stereoselectivity of the double bond of olefins. They are even now widely used for this transformation.