Photochemical Organocatalytic Regio‐ and Enantioselective Conjugate Addition of Allyl Groups to Enals

We report the first catalytic enantioselective conjugate addition of allyl groups to α,β-unsaturated aldehydes. The chemistry exploits visible-light-excitation chiral iminium ions activate silanes towards formation allylic radicals, which are then intercepted stereoselectively. underlying radical mechanism this process overcomes poor regio- and chemoselectivity that traditionally affects allylation enals proceeding via polar pathways. also demonstrate how organocatalytic strategy could selectively install a valuable prenyl fragment at β-carbon enals.