Nickel/Photo-Cocatalyzed C(sp2)-H Allylation of Aldehydes and Formamides.

Herein we report a nickel/photo-cocatalyzed C(sp2)-H allylation of aldehydes and formamides wherein both allyl acetates and allyl alcohols can be used as the allylating agents. In this reaction, radical-type umpolung of the formyl moiety is enabled by tetrabutylammonium decatungstate as a hydrogen-atom-transfer photocatalyst, whereas nickel serves to cleave the C-O bond of allyl acetates or allyl alcohols. The synergistic effect of these two catalysts provides new access to various β,γ-unsaturated ketones and amides with high selectivities.