Palladium-Catalyzed Regioselective C–H Functionalization of Arenes Substituted by Two N‑Heterocycles and Application in Late-Stage Functionalization
journal contributionposted on 13.03.2018, 00:00 by Da-Wei Yin, Gang Liu
Reported herein is a Pd-catalyzed regioselective C–H activation method that is used for C–H deuteration, carbonylation, halogenation, and oxidation of arene substrates substituted by two N-heterocycles. When conducted in acetic acid (AcOH), these reactions occur at the five-membered palladacycle sites, whereas they switch to the six-membered palladacycle sites in trifluoroacetic acid (TFA). This controllable regioselective C–H activation is applied for late-stage functionalization of bioactive molecules. A mechanism study indicated that the regioselectivity is achieved by Brönsted acid–Lewis base interactions and electronic effects (in TFA) and the different kinetic stabilities of palladacycle intermediates (in AcOH).