Z.-W. Ye, W.-B. Yi / Journal of Fluorine Chemistry 129 (2008) 1124–1128
1125
and environmental persistence [32]. Additionally synthesis of
perfluoroalkylated-pyridine ligands is achieved by using expensive
perfluoroalkylated alcohol [29–31,33]. Taking these into consid-
eration, we decided to concentrate on developing a supported-
Pd(OPf)2 catalytic system which is highly active and stable for the
Sonogashira reaction. Our goal was to find out a new catalyst
system effective in the absence of fluorous solvent under aerobic,
copper- and ligand-free conditions and recyclable in water as a
reaction medium. In this paper, we develop a practical protocol for
the copper-free Sonogashira coupling of aryl iodides, bromides and
chlorides with terminal alkynes in water under aerobic conditions
with the Amberlyst A-21 supported Pd(OPf)2 as a catalyst.
over Na2SO4 and p-xylene (1.06 g, 10 mmol) was added as internal
standard for GC analysis. After GC and GC/MS analyses, the
solvents and volatiles were removed under vacuum, and then the
residue was subjected to column chromatography on SiO2 with
cyclohexane as eluent to give diphenylacetylene as white solid
(1.71 g, 94%). The isolated product was analysed by 1H NMR and
13C NMR and compared with authentic samples.
Diphenylacetylene: A white solid; mp: 58–60 8C (lit. 59–61 8C);
1H NMR (300 MHz, TMS, CDCl3)
d
7.45 (m, 4H), 7.23 (m, 6H); 13C
NMR (75 MHz, TMS, CDCl3)
(EI) m/z 178 (M+).
d 89.4, 123.5, 128.2, 128.4, 131.5; MS
4-Methyldiphenylacetylene: A white solid; mp: 67–68 8C (lit. 69–
70 8C); 1H NMR (300 MHz, TMS, CDCl3)
7.45 (m, 2H), 7.36 (d, 2H),
7.27 (m, 3H), 7.11 (d, 2H), 2.32 (s, 3H); 13C NMR (75 MHz, TMS,
d
2. Experimental
CDCl3) d 88.6, 89.4, 120.1, 123.5, 128.2, 129.1, 131.4, 138.3; MS (EI)
2.1. General remarks
m/z 192 (M+).
2-Methyldiphenylacetylene:
A
colorless liquid; 1H NMR
1H NMR and 13C NMR spectra were characterized with a Bruker
Advance RX300 spectrometer. GC analyse was performed on a
Saturn 2000GC/MS instrument. IR spectra were recorded on a
Bomen MB154S infrared analyzer. Elemental analyses were
(300 MHz, TMS, CDCl3) d 7.41 (m, 3H), 7.22 (m, 3H), 7.09 (m,
3H), 2.40 (s, 3H); 13C NMR (75 MHz, TMS, CDCl3)
d 88.7, 89.5, 120.1,
123.6, 128.3, 129.1, 131.3, 138.2; MS (EI) m/z 192 (M+).
4-Methoxydiphenylacetylene: A yellowish solid; mp: 60–62 8C
performed on
a
Yanagimoto MT3CHN recorder. Inductively
(lit. 62–63 8C); 1H NMR (300 MHz, TMS, CDCl3)
d
7.49 (m, 4H), 7.22
coupled plasma (ICP) spectra were measured on an Ultima2C
apparatus. Amberlyst A-21 was commercially obtained from
Weide Chemical Co. of Tianjin. Heptadecafluorooctanesulfonic
acid (Rf8SO3H) was commercially obtained from ARCOS Co.
Amberlyst A-21 was dried at 80 8C in vacuum for 24 h before
being used. Other commercially available reagents were used
without further purification.
(m, 3H), 6.78 (d, 2H), 3.82 (s, 3H); 13C NMR (75 MHz, TMS, CDCl3)
d
55.9, 93.0, 115.0, 128.4, 128.5, 132.4, 133.2, 160.5; MS (EI) m/z 208
(M+).
2-Methoxydiphenylacetylene:
(300 MHz, TMS, CDCl3) 7.45 (m, 3H), 7.23 (m, 3H), 7.06 (m, 1H),
55.4, 92.9,
A
yellowish liquid; 1H NMR
d
6.72 (m, 2H), 3.73 (s, 3H); 13C NMR(75 MHz, TMS, CDCl3)
d
112.1, 128.4, 128.5, 132.4, 133.3, 163.4; MS (EI) m/z 208 (M+).
4-Nitrodiphenylacetylene: A yellowish solid; mp: 118–120 8C
2.2. Preparation of Pd(OPf)2
(lit. 119–120 8C); 1H NMR (300 MHz, TMS, CDCl3)
d
8.14 (d, 2H),
7.61 (d, 2H), 7.47 (m, 2H), 7.28 (m, 3H), 7.11 (d, 2H), 2.32 (s, 3H);
A mixture of a solution of Rf8SO3H (1.23 g, 2.5 mmol) in water
(5 ml) and palladium carbonate (0.17 g, 1.0 mmol) was refluxed
with stirring for 4 h. The resulting gelatin-like solid was collected,
washed and dried at 160 8C for 24 h in vacuum to give a brown
solid (0.84 g, 76%), which does not have a clear melting point up to
13C NMR (75 MHz, TMS, CDCl3)
d 87.6, 94.7, 122.1, 123.5, 128.4,
129.3, 130.2, 131.7, 132.3, 146.9; MS (EI) m/z 223 (M+).
1-Phenyl-1-heptyne: A colorless liquid; 1H NMR (300 MHz, TMS,
CDCl3)
d 7.41 (d, 2H), 7.24 (m, 1H), 7.23 (m, 2H), 2.05 (m, 2H), 1.45
(m, 2H), 1.31 (m, 4H), 0.98 (m, 3H); 13C NMR (75 MHz, TMS, CDCl3)
500 8C, but shrinks around 330 8C and 410 8C. IR (KBr)
1 148 (CF2), 1 080 (SO2), 1 061 (SO2), 752 (S–O) and 640 (C–S) cmÀ1
16F34O6PdS2: calcd. C 17.38, Pd 9.63; found C 17.29, Pd 9.61. 19F
NMR (CF3C6H5):
À126.2, À121.2, À114.2, À81.4.
y
1 230 (CF3),
d 14.2, 18.8, 21.9, 28.7, 30.6, 78.7, 100.1, 122.8, 128.4, 128.5, 132.3;
.
MS (EI) m/z 172 (M+).
C
1-Phenyl-1-octyne: A colorless liquid; 1H NMR (300 MHz, TMS,
d
CDCl3)
d 7.40 (d, 2H), 7.24 (m, 1H), 7.22 (m, 2H), 2.06 (m, 2H), 1.46
(m, 2H), 1.31 (m, 6H), 0.96 (m, 3H); 13C NMR (75 MHz, TMS, CDCl3)
2.3. Preparation of Amberlyst A-21-Pd(OPf)2
d 14.1, 18.7, 22.7, 28.3, 31.0, 78.8, 100.1, 122.8, 128.3, 128.5, 132.4;
MS (EI) m/z 186 (M+).
A mixture of Pd(OPf)2 (2 g) and Amberlyst A-21 (8 g) in acetone
(100 ml) was refluxed with stirring for 24 h. The mixture was
allowed to stand at room temperature for ca. 2 h without stirring.
Then the deposit was separated and washed with water (20 ml 3Â)
and toluene (20 ml 2Â). The isolated solids was dried at 80 8C for
24 h in vacuum to give a gray solid (9.92 g). The solid contained
1.94% Pd by weight based on the ICP analysis. Other phosphine-
free palladium catalysts supported on Amberlyst A-21 were
prepared according to the similar method.
1-Phenyl-1-methoxycarboxyl-acetylene: A colorless liquid; 1H
NMR (300 MHz, TMS, CDCl3)
2H), 3.68 (s, 3H); 13C NMR (75 MHz, TMS, CDCl3)
122.6, 128.4, 128.5, 132.3; MS (EI) m/z 160 (M+).
4-Acetyldiphenylacetylene: A white solid; mp: 98–101 8C (lit.
99–102 8C); 1H NMR (300 MHz, TMS, CDCl3)
7.94 (m, 2H), 7.62
(m, 2H), 7.56 (m, 2H), 7.37 (m, 3H), 2.62 (s, 3H); 13C NMR (75 MHz,
TMS, CDCl3) 26.6, 88.5, 92.7, 122.5, 128.1, 128.3, 128.8, 131.7,
136.1, 197.2; MS (EI) m/z 220 (M+).
2-Acetyldiphenylacetylene:
yellowish liquid; 1H NMR
(300 MHz, TMS, CDCl3) 7.95 (m, 2H), 7.64 (m, 2H), 7.58 (m,
2H), 7.39 (m, 3H), 2.62 (s, 3H); 13C NMR (75 MHz, TMS, CDCl3)
d
7.42 (d, 2H), 7.23 (m, 1H), 7.22 (m,
d
50.8, 82.3, 88.7,
d
d
A
2.4. Typical procedure for the Sonogashira reaction with Amberlyst A-
21-Pd(OPf)2
d
d
26.5, 88.7, 92.7, 122.4, 128.1, 128.3, 128.5, 128.8, 131.7, 136.2,
197.3; MS (EI) m/z 220 (M+).
Iodobenzene (2.04 g, 10 mmol) was added to a mixture of
Amberlyst A-21-Pd(OPf)2 (0.55 g, 1 mol% Pd) and water (10 ml) in a
glass flask under vigorous stirring. After ca. 5 min, phenylacetylene
(1.24 g, 12 mmol) and NEt3 (2.1 ml, 15 mmol) were introduced into
the glass tube. After stirring at 80 8C for 1 h, the reaction mixture
was cooled and diluted with water (10 ml) and toluene (15 ml).
When the filtration was finished, the filtrate was extracted with
hexane (2 Â 10 ml). The combined organic extracts were dried
4-Trifluoromethyldiphenylacetylene: A white solid; mp: 103–
105 8C (lit. 104–106 8C); 1H NMR (300 MHz, TMS, CDCl3)
d
7.58 (m,
2H), 7.54 (m, 4H), 7.32 (m, 3H); 13C NMR (75 MHz, TMS, CDCl3)
d
87.9, 91.8, 122.6, 125.3, 125.4, 127.1, 128.3, 128.8, 131.7, 131.8; MS
(EI) m/z 246 (M+).
2-Trifluoromethyldiphenylacetylene: A colorless liquid; 1H NMR
(300 MHz, TMS, CDCl3)
d 7.59 (m, 2H), 7.55 (m, 4H), 7.31 (m, 3H);