Electronic Tuning of Iron–Oxo‐Mediated CH Activation: Effect of Electron‐Donating Ligand on Selectivity

We have reported previously that an iron(III) complex supported by an anionic pentadentate monoamido ligand, dpaq(H) (dpaq(H) =2-[bis(pyridin-2-ylmethyl)]amino-N-quinolin-8-yl-acetamido), promotes selective CH hydroxylation with H2 O2 with high regioselectivity. Herein, we report on the preparation of Fe(III) -dpaq derivatives that have a series of substituent groups at the 5-position of a quinoline moiety in the parent ligand dpaq(H) (dpaq(R) , R: OMe, H, Cl, and NO2 ), and examine them with respect to their catalytic activity in CH hydroxylation with H2 O2 . As the substituent group becomes more electron-withdrawing, both the selectivity and the turnover number increase, but the selectivity of epoxidation shows the opposite trend.