Strategic Functionalization of Benzylic C(sp3).H Bonds: Unlocking the Potential for Enantioselective δ-Lactonization

Abstract

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(dMMbpbp) 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).