cs6b01539_si_001.pdf (3.56 MB)
Aerobic Direct C(sp2)‑H Hydroxylation of 2‑Arylpyridines by Palladium Catalysis Induced with Aldehyde Auto-Oxidation
journal contribution
posted on 2016-08-09, 00:00 authored by Prasenjit Das, Debajyoti Saha, Dibyajyoti Saha, Joyram GuinHerein we present
a Pd-catalyzed direct C–H hydroxylation
of 2-arylpyridines using molecular oxygen (O2) as the sole
oxidant. The key aspects of the method include: (a) the activation
of molecular oxygen with a nontoxic and inexpensive aldehyde; (b)
an efficient association of the in situ-generated acyl peroxo radical
with palladium catalysis; and (c) convenient operating conditions.
On the basis of the results obtained in a series of control experiments,
a PdII/PdIV catalytic cycle is implicated for
the transformations. Furthermore, the method offers an easy access
to a broad range of substituted 2-(pyridin-2-yl)phenols in good isolated
yields.