Y. Zou, H. Lin, P. A. Maggard, A. Deiters
FULL PAPER
benzimidazol-1-yl)phenyl]ethanone (29),[37] 4-(imidazol-1-yl)aceto-
phenone (31)[38] (all literature-known), as well as N-(2-nitrophen-
yl)caprolactam (21) and 1-[4-(1H-indazol-1-yl)phenyl]ethanone
(28).
homogeneous C–N coupling reactions. Under the optimal
reaction conditions we were able to couple a broad range
of aryl iodides and various nitrogen heterocycles to the cor-
responding products in short reaction times. On the basis
of our mechanistic investigations it appears that the tetra-
nuclear Cu species needs to be converted into mononuclear
units for efficient catalysis. We are currently investigating
the generality of this discovery for Cu-catalyzed C–N cou-
pling reactions.
N-(2-Nitrophenyl)caprolactam (21): Eluted with hexanes/ethyl acet-
ate (2:1, 1:1, 1:2); yield 59%. 1H NMR (400 MHz, CDCl3): δ =
7.91 (d, J = 8.0 Hz, 1 H), 7.59 (t, J = 8.0 Hz, 1 H), 7.38 (t, J =
8.0 Hz, 1 H), 7.27 (d, J = 8.0 Hz, 1 H), 3.87 (br., 1 H), 3.69 (br., 1
H), 2.64 (br., 1 H), 2.74–1.65 (m, 6 H) ppm. 13C NMR (100 MHz,
CDCl3): δ = 175.8, 138.1, 134.1, 128.97, 127.8, 125.2, 53.5, 37.6,
30.2, 28.8, 23.0 ppm. MS: calcd. for C12H14N2NaO3 [M + Na]+
257.1; found 257.1.
Experimental Section
1-[4-(1H-Indazol-1-yl)phenyl]ethanone (28): Eluted with hexanes/
ethyl acetate (6:1); yield 64%. 1H NMR (400 MHz, CDCl3): δ =
8.23 (s, 1 H), 8.12 (d, J = 8.4 Hz, 2 H), 7.87 (d, J = 8.4 Hz, 2 H),
7.84–7.80 (m, 2 H), 7.47 (t, J = 8.0 Hz, 1 H), 7.26 (t, J = 8.0 Hz,
1 H), 2.64 (s, 3 H) ppm. 13C NMR (100 MHz, CDCl3): δ = 197.1,
144.2, 138.8, 136.9, 134.8, 130.1, 128.0, 126.1, 122.4, 121.8, 121.7,
110.8, 26.8 ppm. MS: calcd. for C15H13N2O[M + H]+ 237.1; found
237.1.
General Methods: Unless otherwise stated, all the reagents were
used without further purification. Pyridine was distilled from
CaH2. The C–N coupling reactions were performed under N2 in
flame-dried sealed vials. All products were purified by column
chromatography and the yields were determined by weight. All
spectra were recorded in CDCl3 and the chemical shifts are re-
1
ported relative to CHCl3 (δ = 7.24 ppm for H NMR) and CHCl3
(δ = 77.24 ppm for 13C NMR).
Supporting Information (see footnote on the first page of this arti-
cle): Bond valence sums and additional analytical data for I and
NMR spectra of new compounds.
Synthesis of the Copper Catalyst: Catalyst I was synthesized by
adding Cu2O (28.8 mg, 0.20 mmol), Re2O7 (96.8 mg, 0.20 mmol),
pda (32.0 mg, 0.40 mmol), and deionized H2O (0.40 g, 22.2 mmol)
to an FEP Teflon pouch. The pouch was heat-sealed and placed
inside a 125-mL Teflon®-lined stainless steel reaction vessel which
was backfilled with deionized H2O (ca. 45 mL) before closing. The
reaction vessel was heated to 150 °C for 72 h inside a convection
oven and slowly cooled to room temperature at 6 °C/h. Orange bar-
shaped crystals of I were obtained in about 70% yield. The phase
purities of each compound were Ͼ95% according to the powder
X-ray diffraction data. Cu2(pda)3(ReO4)2·H2O (1771.62): C 16.27,
H 1.59, N 9.49; found C 16.45, H 1.50, N 9.40.
Acknowledgments
The support of this research by the donors of the American Chemi-
cal Society Petroleum Research Fund (#46803-AC10) and the
National Science Foundation (NSF) (grant numbers DMR-
0644833 and CHE-0846756) is acknowledged. We thank P. Boyle
for assistance with the collection of single-crystal X-ray data.
Single-crystal X-ray diffraction data for compound I were collected
with a Bruker–Nonius X8 Apex2 CCD diffractometer at a tem-
perature of 296 K using Mo-Kα radiation (λ = 0.71073 Å). Selected
crystal and refinement data for I: [Cu2(pda)3(ReO4)2·H2O], M =
1771.62, monoclinic, P21/n, a = 10.5513(3), b = 16.0133(5), c =
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General Procedure for the C–N Coupling Reaction: The NH-con-
taining substrate (0.15 mmol), Cs2CO3 (0.2 mmol), and the Cu
complex I (1 mol-%) were added to a solution of the aryl halide
(0.1 mmol) in dry pyridine (1 mL) under nitrogen. The vial was
sealed and heated at 170 °C for 3 h in an oil bath, cooled to room
temperature, filtered, and the filtrate was concentrated under vac-
uum. The product was purified by column chromatography on SiO2
and eluted with hexanes/ethyl acetate to deliver 1-[4-(1H-indol-1-
yl)phenyl]ethanone (3),[25] 1-(4-nitrophenyl)-1H-indole (10),[31] 1-
(2-nitrophenyl)-1H-indole (11),[31] 1-phenyl-1H-indole (12),[32] 1-(4-
methoxyphenyl)-1H-indole (13),[33] 1-(4-pyrazol-1-ylphenyl)ethan-
one (14),[10] 1-(4-nitrophenyl)-1H-pyrazole (15),[10] 1-(2-nitro-
phenyl)-1H-pyrazole (16),[34] 1-phenyl-1H-pyrazole (17),[32] 1-(4-
methoxyphenyl)-1H-pyrazole (18),[32] N-(4-acetylphenyl)caprolact-
am (19),[35] N-(4-nitrophenyl)caprolactam (20),[36] N-phenylcapro-
lactam (22),[35] N-(4-methoxyphenyl)caprolactam (23),[35] 1-[4-(1H-
4158
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