Kinetic Resolution for 1,4-Spin-Center Shift-Based Reduction of Azaarene-Functionalized Secondary and Tertiary...

The spin-center shift (SCS) represents a highly effective strategy in the field of photoredox catalysis for the generation of radical intermediates. Owing to intrinsic mechanistic constraints, the reaction pathway primarily entails a 1,2-radical translocation event, concomitant with a two-electron ionic shift. In contrast, remote SCS events are exceedingly rare, and when observed, they typically exploit C═C bonds within aromatic systems, where aromatization serves as an important thermodynamic driving force for this challenging transformation. Here, we present a proof-of-concept demonstrating that simple olefins can function as effective C═C units to facilitate the elusive 1,4-SCS process. Under cooperative photoredox and chiral Brønsted acid catalysis, a broad range of racemic azaarene-functionalized secondary and tertiary allylic alcohols undergo highly efficient kinetic resolution through 1,4-SCS-based reduction. This chiral acid-mediated pathway promotes the selective removal of γ-alcohols in one enantiomer, furnishing the complementary enantiomer in satisfactory yield with good to excellent enantioselectivity. The synthetic and pharmaceutical value of these enantioenriched azaarene derivatives─together with the challenges in accessing them by conventional methods─highlights the impact of this approach. By introducing an unprecedented π-system platform for remote SCS, this work represents a conceptual advance that opens new avenues for SCS-driven synthetic transformations.