Synergistic Photoredox/Palladium-Catalyzed Remote Meta C–H Olefination of Mandelic Acids

A template-assisted synergistic palladium-photoredox-catalyzed meta C–H olefination of mandelic acids and their derivatives is described. An easily removable nitrile-based template under milder reaction conditions using oxygen as the green oxidant was employed for this transformation. The reaction shows excellent meta selectivity with broad substrate scope and good yields. This method was then extended for the synthesis of meta olefinated drug derivatives such as homatropine and cyclandelate. We also successfully demonstrated this protocol for the ortho olefination of free mandelic acids without any directing groups. Finally, gram-scale synthesis, sequential diolefination, and chemical modifications of the final products were performed to showcase the synthetic utility of the method.