A general Pd-catalyzed α- and γ-benzylation of aldehydes for the formation of quaternary centers

A palladium-catalyzed benzylation of α-branched aldehydes has been developed using benzyl methyl carbonates. The method gives access to congested quaternary centers in the vicinity of one of the most sensitive carbonyl functionalities and displays unprecedented generality with respect to both coupling partners. Evidence for the direct involvement of a Pd-η3-benzyl intermediate is provided. Extension of this strategy to the γ-benzylation of α,β-unsaturated aldehydes is further demonstrated