Asymmetric γ-Allylation of α,β-Unsaturated Aldehydes by Combined Organocatalysis and Transition-Metal Catalysis.

The first asymmetric regio- and diastereodivergent γ-allylation of cyclic α,β-unsaturated aldehydes based on combined organocatalysis and transition-metal catalysis is disclosed. By combining an aminocatalyst with an iridium catalyst, both diastereomers of branched allylated products can be achieved in moderate to good yields and excellent regio- and stereoselectivities. Furthermore, by replacing the iridium catalyst with a palladium catalyst, the linear allylated products are formed in good yields and excellent regio- and enantioselectivities. The developed method thus provides selective access to all six isomers of the γ-allylated product in a divergent fashion by choosing the appropriate combination of organocatalyst, transition-metal catalyst, and ligand.