π-アリルパラジウム錯体の見かけ上の電荷反転 : アリルアルコール類によるカルボニル-アリル化反応への応用

抄録

Palladium-catalyzed carbonyl allylation by allylic alcohols with SnCl₂ smoothly proceeds in aqueous medium under air. The actual allylating agent in the carbonyl allylation by allyl alcohol in dry medium is allyltrichlorotin, which is prepared via (1) oxidative addition of allyl alcohol to Pd (0) complex with SnCl₂, (2) insertion of SnCl₂ to π-allylpalladium complex, followed by (3) reductive elimination of π-allylpalladium trichlorostannate. Allylic alcohols, preparing π-allylpalladium complexes, function as synthons of allylic carbanions. In other words, this implies the apparent charge reversal of electrophilic π-allylpalladium complexes. The carbonyl allylation by allylic alcohols can achieve high chemo-, regio-, and diastereoselection by the choice of solvent, and can be applied to chelation-controlled diastereoselection in polar solvents.