Strategic Functionalization of Benzylic C(sp ³ )H Bonds: Unlocking the Potential for Enantioselective δ ‐Lactonization

Recent advancements in bio‐inspired Mn‐catalyzed directed oxidations of carboxylic acids have provided promising pathways for the synthesis of a wide variety of chiral γ ‐lactones. In our current study, however, we have established a catalytic route using 0.25 mol% of electron‐rich Mn‐catalyst Mn( dMM bpbp) that redirects the lactonization reaction to the δ ‐position, with high enantiomeric excess (over 80%). To the best of our knowledge, selective oxidative δ ‐lactonizations in an enantioselective pathway have not been reported earlier using a transition metal‐catalyzed manner. Our methodology can be extended to the enantioselective synthesis of benzo‐fused δ ‐lactones (up to 70% yield and 62% ee).