A Photoredox Keck Allylation Reaction Using Riboflavin as the Radical Initiator

An efficient Keck allylation using Riboflavin Tetraacetate (RFTA) and blue LED light as the radical initiator is reported. The method is effective with both primary and secondary α‐chloro‐ and α‐bromoketones as well as α‐iodo‐ and α‐bromoesters. Additionally, this procedure requires only 5 mol% of photocatalyst, unlike the standard 20 mol% of AIBN typically employed in this type of reaction.