A direct intermolecular addition of 1,3-dithianes to alkenes has been accomplished via visible-light mediated photocatalysis. This new process proceeds in moderate to excellent yields and eliminates the need for pre-functionalization of substrates. Electronic tuning of the 1,3-dithiane plays a vital role in ensuring reactivity. Both aromatic and aliphatic aldehyde-derived 1,3-dithianes are compatible. This radical umpolung strategy allows the synthesis of γ-keto-α-amino acid derivatives.
