Abstract
A density functional theory (DFT) study was performed to evaluate the reaction mechanism
of the C–N bond formation under an integrated hydrogen atom transfer/radical-polar
crossover photoredox catalytic cycle. The regioselective activation of a model substrate,
including three reactive positions (3° benzylic C–H bond, 2° benzylic C–H bond, and
primary C–Cl bond) was addressed to distinguish among the radical C–H activation mechanism
and the standard SN2 reaction. We demonstrated that activation of tertiary benzylic C–H bond is the most
favored and forms exclusively the experimentally observed product. In addition, the
whole photoredox catalytic cycle, including the outer-sphere electron-transfer steps,
was characterized computationally.
Key words
photoredox catalysis - C–N bond formation - density functional theory - regioselectivity
- reaction mechanism
