jo6b01933_si_002.cif (17.8 kB)
Pd(II)-Catalyzed Bidentate Directing Group-Aided Chemoselective Acetoxylation of Remote ε‑C(sp2)–H Bonds in Heteroaryl–Aryl-Based Biaryl Systems
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posted on 2016-11-18, 00:00 authored by Naveen, Vadla Rajkumar, Srinivasarao Arulananda Babu, Bojan GopalakrishnanIn
this Article, we report our successful attempt on the Pd(II)-catalyzed,
bidentate directing group-aided, chemoselective acetoxylation/substitution
of remote ε-C(sp2)–H bonds using heteroaryl–aryl-based
biaryl systems. While the bidentate directing group (BDG)-aided, C–H
activation, and functionalization/acetoxylation of the β-, γ-,
and δ-C–H bonds of the appropriate carboxamide systems
were well documented, there exist only rare reports dealing with the
C–H activation and functionalization of remote ε-C–H
bonds of appropriate substrates. Especially, the BDG-aided chemoselective
acetoxylation of the remote ε-C(sp2)–H bond
over cyclization has not been explored well. Accordingly, in this
work, the treatment of various picolinamides/oxalylamides/pyrazine-2-carboxamides 4/7/9/11, which were
derived from the corresponding C-3 arylated furfurylamines or thiophen-2-ylmethanamines
with PhI(OAc)2 in the presence of the Pd(OAc)2 catalyst, successfully afforded the corresponding ε-C–H
acetoxylated products. The chemoselective acetoxylation of the ε-C–H
bond was possible and facilitated by the biaryl substrate 4/7/9/11 and not by the biaryl
substrate 2a.