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Vicinal difunctionalization
Vicinal difunctionalization refers to a chemical reaction involving transformations at two adjacent centers (most commonly carbons). This transformation can be accomplished in α,β-unsaturated carbonyl compounds via the conjugate addition of a nucleophile to the β-position followed by trapping of the resulting enolate with an electrophile at the α-position. When the nucleophile is an enolate and the electrophile a proton, the reaction is called Michael addition.〔Chapdelaine, M. J.; Hulce, M. ''Org. React.'' 1990, ''38'', 227-294. 〕
==Introduction==
Vicinal difunctionalization reactions, most generally, lead to new bonds at two adjacent carbon atoms. Often this takes place in a stereocontrolled fashion, particularly if both bonds are formed simultaneously, as in the Diels-Alder reaction. Activated double bonds represent a useful handle for vicinal difunctionalization because they can act as both nucleophiles and electrophiles—one carbon is necessarily electron poor, and the other electron rich. In the presence of a nucleophile and an electrophile, then, the two carbons of a double bond can act as a "relay," mediating electron flow from the nucleophile to the electrophile with the formation of ''two'', rather than the usual one, chemical bonds.
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Most often, the nucleophile employed in this context is an organometallic compound and the electrophile is an alkyl halide.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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