α-Allylation of Aldehydes via a Conjugate Addition-Elimination Pathway

Significance

A catalytic asymmetric α-alkylation of aldehydes with allylic bromides 3, proceeding via an S_N2′-type conjugate addition-elimination pathway, has been reported. Stoichiometric DMAP and catalytic amounts of secondary amine 1 delivered alkylation products 4 in moderate yields with high enantioselectivity. Using a more complex electrophile 6, product 7 was obtained with excellent enantioselectivity albeit in only 40% yield after three days. In addition to moderate yields, the main drawback of the reported method is the use of three equivalents of the aldehyde.