Cooperative Polar/Steric Strategy in Achieving Site‐Selective Photocatalyzed C(sp 3 )−H Functionalization

Synergistic control over the S H 2 transition states of hydrogen abstraction exploiting polar and steric effects provides a promising cooperative strategy for site‐selective C(sp 3 )−H functionalization using decatungstate anion photocatalysis. By using this photocatalytic approach, the C−H bonds of substituted lactones and cyclic ketones were functionalized selectively. In the remarkable case of 2‐isoamyl 4‐tert‐butyl cyclohexanone ( 1 t ) bearing five methyl, five methylene, and three methine C−H bonds, one methine C−H bond in the isoamyl tether was selectively functionalized.