Palladium-Catalyzed Regioselective C–H Functionalization of Arenes Substituted by Two N-Heterocycles and Application in Late-Stage Functionalization
2018
Yin, Da-Wei | Liu, Gang
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).
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