Article
BULLETIN OF THE
ISSN (Print) 0253-2964 | (Online) 1229-5949
KOREAN CHEMICAL SOCIETY
Experimental
dimethylacetamide (DMA) (1.0 mL), aryl halide
(0.5 mmol), trimethoxyphenylsilane (1.5 mmol), KF
General Remarks. All commercially available chemicals
were purchased from Aldrich Chemical Co. or Tokyo
Chemical Industry Co. and used without additional purifica-
tion unless otherwise noted. Solvents were used after
degassing for 15 min. All reaction products were isolated
through flash column chromatography and identified
(1.5 mmol),
tetrabutylammonium
iodide
(TBAI)
(0.1 mmol), and Pd–Fe3O4 catalyst (1 mol%) were added
to a vial, which was equipped with a magnetic bar and
purged with argon gas. The vial was sealed and the reaction
mixture was heated to 150ꢀC for 16 h with vigorous stir-
ring. After the reaction, the mixture was cooled to room
temperature and the catalyst was collected using an external
magnet. The solution containing products was diluted and
extracted between dichloromethane (10 mL) and H2O
(10 mL). The organic layer was dried over MgSO4, filtered,
and concentrated under reduced pressure. The residue was
purified by silica-gel column chromatography using a 1:6
mixture of ethyl acetate and n-hexane as an eluent to fur-
nish the desired products.
General Procedure for Recycling. After removal of the
solution containing the product, MeOH (5 mL) was added
and the mixture solution was sonicated for 1 min. Then the
Pd–Fe3O4 catalyst was separated with the use of an external
magnet. The recovered catalyst was washed five times with
MeOH (10 mL), twice with H2O (5 mL), and finally twice
with MeOH (5 mL) and dried before use for the next
reaction.
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through comparison with authentic H and 13C NMR spec-
tra. Spectral data were obtained on an Agilent MR DD2
(400 MHz) spectrophotometer. Flash column chromatogra-
phy was performed on silica gel and elution was performed
with a mixture of hexanes–ethyl acetate. Reaction progress
was monitored on thin layer chromatography (TLC) plates
and the spots on the TLC plates were visualized by staining
after dipping them into a KMnO4 solution and/or under
254 nm ultraviolet light. Reaction progress was monitored
through GC analysis using a Hewlett Packard 5890 Gas
Chromatograph with mesitylene as an internal standard.
Sonication was executed in a 250 W ultrasonic container
(SD-ULTRASONIC CO., Ltd, SD-D250H).
Preparation of Pd–Fe3O4 Heterodimer Nanocrystals.
Pd–Fe3O4 nanocrystals were prepared according to a
reported procedure.18–21 The synthesis was achieved by
one-pot thermal decomposition of a mixture solution which
is composed of Fe(acac)3, Pd(acac)2, oleic acid, and oleyla-
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Biphenyl 3a: H NMR (400 MHz, CDCl3) δ 7.70–7.66
(m, 4H), 7.56–7.49 (m, 4H), 7.46–7.40 (m, 2H); 13C NMR
(100 MHz, CDCl3) δ 141.3, 128.8, 127.3, 127.2.
mine. In
a
usual procedure, Pd(acac)2 (100 mg,
0.330 mmol) and Fe(acac)3 (7.0 g, 20.0 mmol) were added
to a mixture of oleic acid (80 mL, 250 mmol) and oleyla-
mine (60 mL, 175 mmol). The mixture was heated to
120ꢀC under reduced pressure while being vigorously stir-
red for 2 h. The resulting mixture was heated to 220ꢀC
under argon atmosphere at a heating rate of 2ꢀC/min and
kept at the temperature for 30 min. Then, it was further
heated to 300ꢀC at the same heating rate and kept for
30 min at 300ꢀC. Subsequently, the mixture was cooled to
room temperature and washed with 250 mL of ethanol and
a black supernatant was decanted. The residue was dis-
persed in ethanol (125 mL) through sonication and pro-
ducts were collected by centrifugation (1700 rpm, 15 min).
The Pd–Fe3O4 product was again dispersed in 150 mL of
n-hexane and collected through using an external magnet.
This washing process was repeated until the decanted hex-
ane did not show any color. After several repeated washing
cycles, the Pd–Fe3O4 nanocrystals were accumulated and
dried under vacuum to furnish 1.23 g of dark solid.
2-Fluorobiphenyl 3b: 1H NMR (400 MHz, CDCl3) δ
7.54–7.52 (m, 2H), 7.42–7.37 (m, 3H), 7.34–7.24 (m, 2H),
7.17–7.08 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 158.6
(d, J = 246.2 Hz), 135.9, 130.9 (d, J = 3.6 Hz), 129.1 (d,
J = 2.9 Hz), 129.1 (d, J = 23.5 Hz), 129.0 (d, J = 8.2 Hz),
128.5, 127.7, 124.4 (d, J = 3.6 Hz), 116.1 (d,
J = 22.5 Hz); 19F NMR (377 MHz, CDCl3) δ −118.4.
4-Fluorobiphenyl 3c: 1H NMR (400 MHz, CDCl3) δ
7.55–7.51 (m, 4H), 7.45–7.40 (m, 2H), 7.36–7.33 (m, 1H),
7.14–7.09 (m, 2H); 13C NMR (100 MHz, CDCl3) δ 161.3
(d, J = 244.5 Hz), 140.3, 137.4 (d, J = 3.0 Hz), 128.9,
128.7 (d, J = 7.5 Hz), 127.3, 127.0, 115.8 (d, J = 21 Hz);
19F NMR (377 MHz, CDCl3) δ −116.4.
4-(Trifluoromethyl)biphenyl 3d: 1H NMR (400 MHz,
CDCl3)
δ 7.62–7.56 (m, 4H), 7.52–7.49 (m, 2H),
7.41–7.37 (m, 2H), 7.35–7.33 (m, 1H); 13C NMR
(100 MHz, CDCl3) δ 144.8, 139.8, 129.3, 129.1, 128.9,
128.3, 127.5, 127.3, 125.8, 123.2; 19F NMR (377 MHz,
CDCl3) δ −62.42.
Characterization of Pd–Fe3O4 Heterodimer Nanocrys-
tals. All transmission electron microscopy (TEM) images
were obtained using a JEOL EM-2010 microscope at an
accelerating voltage of 120 kV. The powder X-ray diffrac-
tion (XRD) was obtained through the use of a Bruker AXS
D8 FOCUS (2θ: 5–100, scan speed: 2ꢀC/min, Cu Kα radia-
tion: λ = 1.54056 nm, generator: 40 kV, 40 m).
3,5-Bis(trifluoromethyl)biphenyl
3e:
1H
NMR
(400 MHz, CDCl3) δ 8.01 (s, 2H), 7.86 (s, 1H), 7.61–7.59
(m, 2H), 7.52–7.45 (m, 3H); 13C NMR (100 MHz, CDCl3)
δ 143.1, 138.1, 132.3 (q, J = 33.0 Hz), 129.1, 128.7,
127.0, 124.3, 122.1, 120.9; 19F NMR (377 MHz, CDCl3)
δ −63.22.
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2-Nitrobiphenyl 3f: H NMR (400 MHz, CDCl3) δ 7.82
General Procedure for Hiyama Cross-Coupling Reac-
tions. A typical procedure for the cross-coupling reaction
using the nanocrystals is as follows: degassed N,N0-
(d, 1H), 7.59–7.56 (m, 1H), 7.45–7.38 (m, 5H), 7.30–7.29
(m, 2H); 13C NMR (100 MHz, CDCl3) δ 149.3, 137.4,
136.3, 132.3, 131.9, 128.7, 128.1, 127.9, 124.0.
Bull. Korean Chem. Soc. 2016
© 2016 Korean Chemical Society, Seoul & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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