Palladium-catalysed coupling of terminal alkynes with aryl halides aided by catalytic zinc

Article abstract of DOI:10.1016/S0022-328X(98)00765-7

The palladium-catalysed coupling of aryl halides with terminal alkynes can be performed using base, zinc chloride and sodium iodide. This protocol represents a convenient method for the generation of nucleophilic acetylides in situ.

Full text of DOI:10.1016/S0022-328X(98)00765-7

Journal of Organometallic Chemistry 570 (1998) 219–224
Palladium-catalysed coupling of terminal alkynes with aryl halides
aided by catalytic zinc
Geoffrey T. Crisp *, Peter D. Turner, Kim A. Stephens
Department of Chemistry, The Uni6ersity of Adelaide, Adelaide, South Australia, 5005, Australia
Received 6 April 1998
Abstract
The palladium-catalysed coupling of aryl halides with terminal alkynes can be performed using base, zinc chloride and sodium
iodide. This protocol represents a convenient method for the generation of nucleophilic acetylides in situ. © 1998 Elsevier Science
S.A. All rights reserved.
Keywords: Palladium catalysis; Coupling of oxyhalides with alkynes; Nucleophilic alkynes
1. Introduction
quantities of potentially unstable reagents. A potential
disadvantage to the use of zinc acetylides is that they
have been prepared by the addition of a strong base to
a terminal alkyne and ZnCl2 added to effect cation
exchange. The resulting solution is air and moisture
sensitive and cannot be stored for long periods without
deterioration. As aryl alkynes are becoming important
intermediates in the synthesis of novel molecular poly-
mers ([6]a, b) and functional molecular devices ([7]a, b),
new methodologies for their synthesis under mild con-
ditions are sought. We were interested in establishing a
procedure in which the zinc acetylide (or an equivalent
nucleophilic species) could be generated in situ, as for
the copper acetylides and so provide a more convenient
protocol for the use of zinc acetylides in palladium
catalysed couplings. In this paper we report a prelimi-
nary investigation into the scope and limitations of the
use of zinc acetylides (or an equivalent nucleophilic
species) generated in situ.
The ability of terminal alkynes to couple with aryl
halides using the traditional methodology of a palla-
dium catalyst (either palladium(0) or (II)), a base (fre-
quently a secondary or tertiary amine) and copper
iodide (for the generation of the copper acetylide inter-
mediate), has been known for many years [1]. Several
recent alternatives have been reported to this general
theme and all proceed well in the absence of a copper
co-catalyst but with modified reaction conditions. Ex-
amples include coupling in the presence of Pd(PPh3)4
and piperidine or pyrrolidine [2], the use of water
soluble phosphine ligands and aqueous solvents [3] and
the use of Pd(OAc)2 in aqueous solvents with quater-
nary ammonium salts [4]. Numerous examples of
organometallic acetylide derivatives have been reported
including magnesium, zinc and tin and all have been
shown to couple efficiently with organic electrophiles in
the presence of palladium ([5]a, b). The inherent advan-
tage of the traditional copper acetylides is the ability to
catalytically generate the nucleophilic acetylides in situ
and avoid the necessity of preparing and storing large
2. Results and discussion
2.1. Acti6ated substrates
* Corresponding author: Fax: +61
8
3034358; e-mail:
gcrisp@chemistry.adelaide.edu.au
An initial treatment of iodobenzene with phenyl-
0022-328X/98/$ - see front matter © 1998 Elsevier Science S.A. All rights reserved.
PII S0022-328X(98)00765-7

220
G.T. Crisp et al. / Journal of Organometallic Chemistry 570 (1998) 219–224
laminopyridine (DMAP) was used in addition to the
triethylamine at 60°C (entry 9, Table 1).
acetylene in the presence of Pd(PPh3)4, zinc chloride
and piperidine at room temperature gave none of the
desired diphenylacetylene over a 4-h period (Eq 1).
Addition of a small crystal of iodine to the solution
gave an immediate reaction as evidenced by the
formation of a solid (piperidine hydroiodide) and
(1)
The traditional copper iodide method gave
diphenylacetylene in 100% yield after about 10min at
room temperature (entry 10, Table 1), so the zinc
chloride/iodide combination effects a slower coupling
for this very reactive substrate. Iodide is not the only
nucleophile which is capable of promoting the
transformation as azide also gave an excellent yield of
product (entry 11, Table 1). In order to probe the
scope of the reaction further the optimum conditions
of piperidine, ZnCl2 and NaI were applied to the
coupling of iodobenzene with 1-hexyne, trim-
ethylsilylacetylene, 1,8-octadiyne and 2-propyn-1-ol and
each gave an excellent yield of the expected product
(entries 12–15, Table 1). The reaction with trimethyl-
silylacetylene was considerably slower than the other
substrates and required 20 h at room tempera-
ture whereas all other substrates coupled completely in
1–3 h.
after
1 h of stirring followed by an extractive
workup, diphenylacetylene was isolated in 80% yield
(entry 1, Table 1). The yield of diphenylacetylene was
not affected by the use of zinc chloride which had
not been specifically dried (compare entries 1 and 2,
Table 1) showing that the reaction is tolerant of small
quantities of water. Only
a very slow reaction
occurred in the absence of a source of iodide and
only a catalytic quantity of either iodine or iodide
was necessary to promote the coupling (entries 2 and
3, Table 1). Interestingly, zinc iodide did not promote
the conversion as efficiently as a combination of zinc
chloride and sodium iodide, so the effect of the
iodine or iodide cannot simply be formation of zinc
iodide (entry 5, Table 1). Replacing piperidine as the
solvent with DMF and adding only 1.5 equivalents of
piperidine gave the same yield of product as neat
piperidine (entry 6, Table 1). No reaction occurred in
the absence of a palladium catalyst (entry 4, Table 1)
and no reaction occurred at room temperature when
triethylamine replaced piperidine as the solvent (entry
7, Table 1), although a slow conversion did occur at
60°C (entry 8, Table 1), or when N,N-dimethy-
2.2. Non-acti6ated substrates
The limits of this new protocol for the coupling were
then investigated using the non activated 1-hexyne with
the less reactive electrophile 4-bromoanisole (Eq 2) and
the results are summarised in Table 2. For Table 1 the
% yield represented that of the isolated product,
whereas in Table 2 the % conversion of 4-bromoanisole
to product has been calculated using gas liquid chro-
matography and an internal standard. No reaction
occurred at room temperature as expected for the lower
rate of oxidative addition of electron rich aryl bromides
to palladium(O) and so all reactions were performed at
60°C.
Table 1
Coupling of iodobenzene with terminal alkynes in Eq. 1
Entry Solvent/base
R
Additive
% Yield
1
2
3
4
5
6
7
8
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
NEt3
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
C4H9
Me3Si
ZnCl2/I2
ZnClb2/I2
ZnClc2/NaI
ZnClc2/NaI
ZnI2
80a
94
94
0d
34
26e
0
ZnI2
ZnI2
ZnI2
(2)
NEt3
34f
44
100
9
NEt3/DMAP
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
ZnClc2/NaI
CuI
10
11
12
13
14
15
Using piperidine as both the base and solvent with
ZnCl2 and NaI as the additives, various metal catalysts
were tested for their efficacy in promoting the coupling.
Under the standard conditions of Pd(PPh3)4 as catalyst,
60°C was found to give a reasonable rate of formation
of 1 with minimum decomposition of the catalyst,
minimum reduction of 4-bromoanisole and minimum
formation of alkyne dimer (entry 1, Table 2). Homo-
coupling of terminal alkynes during traditional cop-
per(I) catalysed heterocoupling reactions has been
reported to be an unwanted side reaction when less
reactive electrophiles such as electron rich arylbromides
ZnClc2/NaN3 100a
ZnClc2/NaI
ZnClc2/NaI
94a
100g
100a
100a
HCꢀC(CH2)4 ZnClc2/NaI
HOCH2
ZnClc2/NaI
a Pd(PPh3)4 5%, base as solvent, room temperature, reaction time B1
h.
b ZnCl2 dried under high vacuum.
c ZnCl2 used without drying.
d Reaction without Pd(PPh3)4
e DMF used as solvent with 3 equivalents of piperidine
f Reaction mixture heated at 60°C
g Reaction mixture stirred for 18 h.

G.T. Crisp et al. / Journal of Organometallic Chemistry 570 (1998) 219–224
221
Table 2
gave an initial rapid conversion but the catalyst decom-
posed after 4 h and no further conversion took place
(entry 10, Table 2). Dimer formation and reduction of
4-bromoanisole were major side reactions under these
conditions. Nickel catalysts gave no product, no dimer
formation and no reduction under these conditions
(entries 11–12, Table 2). Since Pd(PPh3)4 appeared to
be a suitable catalyst the effect of changing the solvent
and base was investigated. The polar aprotic solvent
DMF with 1.5 equivalents of piperidine gave a good
conversion to 1 within 5 h (entry 13, Table 2). Increas-
ing the solvent polarity by using DMSO with 1.5
equivalents of piperidine gave a faster reaction with
fewer side products, as did the combination of DMSO
with PdCl2(PPh3)2 (entries 14–15, Table 2). The most
efficacious combination was DMSO with 1.5 equiva-
lents of DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) and
1.5 equivalents of NEt3 (entry 16, Table 2). Nucle-
ophilic bases are necessary for this coupling protocol
and this would imply a coordination of the base to the
zinc intermediate which either stabilizers and/or acti-
vates the nucleophile. The use of N-methyl imidazole
gave a reasonable yield of product in DMSO but the
reaction was not as efficient as with DBU (entry 17,
Table 2). The most efficient protocol was the use of
DBU in DMSO with zinc dust instead of zinc chloride
and this gave the most rapid reaction with minimal
reduction and dimer formation (entry 18, Table 2).
The coupling of phenylacetylene with dimethyl 5-bro-
moisophthalate was examined and showed that the
ester functional group is not affected by the reaction
conditions with the product 2 being isolated in 70 and
75% yield under two different sets of conditions (Eq. 3
and Section 3).
Coupling of p-methoxybromobenzene with 1-hexyne
Entry Solvent/base
Catalyst
Additive
%1a
1
2
Piperidine
Piperidine
Pd(PPh3)4
PdCl2P(o-
tolyl3)2
ZnCl2/NaI
ZnCl2/NaI
86b
67b
3
4
5
6
Piperidine
Piperidine
Piperidine
Piperidine
–
ZnCl2/NaI
CuI
ZnCl2/NaI
ZnCl2/NaI
8c
Pd(PPh3)4
PdCl2(PBu3)2
PdCl2(AsPh3)2
/AsPh3
Pd2dba3/PPh3
Pd2dba3/dppe
Pd2dba3/dppf
Pd(OAc)2/PPh3 ZnCl2/NaI
Niacac2/PPh3
NiCl2(PPh3)2
71b
0c
15c
7
8
9
10
11
12
13
14
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
Piperidine
ZnCl2/NaI
ZnCl2/NaI
ZnCl2/NaI
15c
19c
9c
47c
0c
ZnCl2/NaI
ZnCl2/NaI
ZnCl2/NaI
ZnCl2/NaI
0c
DMF/piperidine Pd(PPh3)4
76b
77b
DMSO/pipe-
ridine
DMSO/pipe-
ridine
DMSO/DBU/
NEt3
DMSO/NMI/
NEt3
Pd(PPh3)4
PdCl2(PPh3)2
Pd(PPh3)4
Pd(PPh3)4
Pd(PPh3)4
15
16
17
18
ZnCl2/NaI
ZnCl2/NaI
ZnCl2/NaI
Zn dust/NaI
88b
88b
60b
100d
DMSO/DBU/
NEt3
a % Yield of 1 based on n-decane standard and glc analysis of the
reaction mixture.
b Pd(PPh3)4 5%, base as solvent, 60°C, reaction time, 4–8 h.
c Reaction time, 12–14 h.
d Reaction time, 2–3 h.
or triflates. [9] Reactions were conducted with only
1.2–1.5 equivalents of 1-hexyne in order to determine
the extent of competition between homo- and
heterocoupling.
(3)
Substitution of P(o-tolyl)3 for PPh3 gave a reasonable
yield of 1 although the reaction was noticeably slower
and required 12 h for completion in contrast to 4–6 h
for Pd(PPh3)4 (entry 4, Table 2). Very little conversion
was effected without the presence of a metal catalyst
(entry 3, Table 2). The traditional copper iodide
method gave 1 in similar yield and at a similar rate to
the ZnCl2 and NaI method when Pd(PPh3)4 was the
catalyst (entry 4, Table 2). Substituting the electron rich
tertiary phosphine PBu3 for PPh3 gave no product after
24 h (entry 5, Table 2) and a AsPh3 substituted catalyst
gave a poor conversion to 1 due to premature catalyst
decomposition at 60°C (entry 6, Table 2). Reducing the
ratio of phosphine ligand to palladium from 4:1 to 2:1
for monodentate and 1:1 for bidentate ligands gave low
conversions of 4-bromoanisole and catalysts which de-
composed after 4–5 h (entries 7–9, Table 2). These
catalysts gave very little dimer formation from homo-
coupling of 1-hexyne but significant reduction of 4-bro-
moanisole. The combination of Pd(OAc)2 and PPh3
In conclusion, an alternative protocol has been devel-
oped for the palladium catalysed coupling of terminal
alkynes with aryl halides. This method appears to be as
efficient as the traditional methodology using copper
iodide and base to generate nucleophilic acetylides in
situ. It offers a distinct advantage over the use of zinc
acetylides which are prepared using a strong base and
strictly anhydrous conditions. The nature of the active
nucleophile in this protocol is not clear at this stage. It
would seem unlikely that the active nucleophile is iden-
tical to that formed from a terminal alkyne, a strong
base and ZnCl2. The requirement for a nucleophilc base
suggests a coordination to the zinc either before or after
the activation of the terminal alkyne. We are presently
investigating the nature of the nucleophilic species and
the mechanism of the coupling and these results will be
reported in due course.

222
G.T. Crisp et al. / Journal of Organometallic Chemistry 570 (1998) 219–224
3. Experimental
3.2. 1-(1-Hexynyl)benzene
1H-NMR spectra were recorded at 300 MHz on a
Varian Gemini NMR spectrometer (75.47 MHz for
13C) or at 200 MHz on a Varian Gemini spectrometer
(50.28 MHz for 13C), using a dual 5-mm 13C/1H probe.
All spectra were recorded as dilute solutions in deuteri-
ochloroform using tetramethylsilane as an internal
standard. Melting points were determined on a Kofler
hot-stage micro-melting point apparatus equipped with
a Reichart microscope and are uncorrected. Electron
impact mass spectra were recorded at 70 eV on a
Vacuum Generators ZAB 2HF mass spectrometer.
Thin layer chromatography (TLC) was carried out
using Merck Silica gel (Kieselgel) 60F254 on aluminium
backed plates. TLC plates were visualised using 253 nm
ultraviolet light and/or by an acidic solution of 10%
ammonium molybdate or 1% potassium permanganate
solution. Flash and squat column chromatography was
carried out using Merck Silica gel 60 (particle size
0.040–0.063mm).
To a solution of iodobenzene (0.25 ml, 2.23 mmol) in
piperidine (3 ml) was added Pd(PPh3)4 (129 mg, 1.12×
10−4 mol), 1-hexyne (0.28 ml, 2.46 mmol), ZnCl2 (not
dried, 61 mg, 4.47×10−4 mol) and a crystal of iodine.
The resulting suspension was then stirred at room
temperature for 2 h. The reaction mixture was then
added to CH2Cl2 (40 ml), washed with saturated NH4Cl
(40 ml) and the aqueous layer re-extracted with another
portion of CH2Cl2 (40 ml). The organic layers were
combined, dried and the solvent removed. The crude
product was passed through a squat column of silica
(eluant:- hexane:dichloromethane 3:1 (v/v)) to give the
title compound as a golden oil (333 mg, 94%). 1H-
NMR:0.87 (t, 2H, J 7 Hz), 1.51 (m, 4H), 2.40 (t, 2H, J
7Hz), 7.26 (m, 3H), 7.39 (m, 2H); 13C-NMR: 13.4, 19.0,
21.9, 30.8, 80.6 (CꢀC), 90.4 (CꢀC), 124.2, 127.4, 128.2,
131.6; m/z: 158 (M+, 41%), 143 (65), 129 (69), 115
(100); Ir (neat) (wmax, cm−1) 2231 (CꢀC).
3.3. Trimethyl(2-phenyl-1-ethynyl)silane
Solvents were purified and dried using standard labo-
ratory procedures [8]. All organic extracts were dried
over anhydrous magnesium sulphate. All solvents for
palladium catalysed coupling reactions were degassed
by the freeze-pump-thaw method and kept under an
atmosphere of nitrogen.
The procedure was analogous to that for dipheny-
lacetylene except that the solution was stirred for 20 h.
The crude product was passed through a squat column
of silica (eluant:-hexane:dichloromethane 5:1 (v/v)) to
give the title compound as a colourless oil (quantita-
The following compounds were purchased from
1
tive). H-NMR: 0.25 (s, 9H), 7.30 (m, 3H), 7.47 (m,
Aldrich:
NiCl2(PPh3)2,
Ni(acac)2,
PdCl2(PBu3)2,
2H); 13C-NMR: −0.1, 93.9 (CꢀC), 105.2 (CꢀC), 123.2,
128.2, 128.5, 131.9; Ir (neat) (wmax, cm−1) 2160 (CꢀC).
PdCl2(PPh3)2 PdCl2dppe and Pd(OAc)2. The following
compounds were prepared from literature procedures:
PdCl2[P(o-tolyl)3]2 [10], PdCl2(AsPh3)2 [10], Pd2dba3
[11] and Pd[PPh3]4 [12]. Reactions were performed un-
der an atmosphere of nitrogen unless otherwise
mentioned.
3.4. 1,8-Diphenyl-1,7-octadiyne
The procedure was analogous to that for dipheny-
lacetylene except that the solution was stirred for 3 h.
The crude product was passed through a squat column
of silica (eluant:-hexane:dichloromethane 4:1 (v/v)) and
then further purified by flash chromatography (eluant:-
hexane:dichloromethane 3:1 (v/v), Rf 0.43) to give the
3.1. Diphenylacetylene
To a solution of iodobenzene (0.20 ml, 1.78 mmol) in
degassed piperidine (3 ml) was added Pd(PPh3)4 (105
mg, 8.93×10−5 mol), phenylacetylene (0.20 ml, 1.82
mmol), zinc chloride (not dried) (50 mg, 3.67×10−4
mol) and sodium iodide (27 mg, 1.78×10−4 mol). The
resulting suspension was then stirred under nitrogen at
room temperature for 45 min. The reaction mixture was
then added to dichloromethane (40 ml), washed with
saturated ammonium chloride (40 ml) and the aqueous
layer extracted with an additional portion of
dichloromethane (40 ml). The organic layers were com-
bined, dried and the solvent removed. The resulting oil
was passed down a short squat column of silica (5:1
hexane:dichloromethane) and the solid obtained was
recrystallised from an ethanol/water mixture to give
tolan as colourless plates (272 mg, 86%). Mp. 58.5–60°
(Mp. lit. 59–61°). [13] C-NMR: 89.4 (CꢀC), 123.4,
128.2, 128.3, 131.6; m/z: 178 (M+, 100%), 152 (7), 126
(4).
1
title compound as a colourless oil (quantitative). H-
NMR: 1.86 (m, 4H), 2.55 (m, 4H), 7.33 (m, 6H), 7.51
(m, 4H); 13C-NMR: 18.8, 27.7, 80.9 (CꢀC), 89.7 (CꢀC),
123.9, 127.5, 128.1, 131.5; m/z 258 (M+, 100%), 230
(79); Ir (neat) (wmax, cm−1) 2230 (CꢀC).
3.5. 3-Phenyl-2-propyn-1-ol
The procedure was analogous to that for dipheny-
lacetylene. The crude product was purified by flash
chromatography (eluant:- dichloromethane:ethyl ac-
etate 10:1 (v/v), Rf 0.57) to give the title compound as
1
a golden oil (quantitative). H-NMR (l, ppm): 4.49 (br
s, 2H), 7.26 (m, 3H), 7.43 (m, 2H); 13C-NMR (l, ppm):
51.0, 85.3 (CꢀC), 87.3 (CꢀC), 122.5 (q), 128.2, 128.3,
131.6; m/z 132 (M+, 6%), 131 (9), 115 (4); ir (neat)
(wmax, cm−1) 2238 (CꢀC, stretching).

G.T. Crisp et al. / Journal of Organometallic Chemistry 570 (1998) 219–224
223
3.6. 1-(1-Hexynyl)-4-methoxybenzene (1)
(0.09 ml, 8.21×10−4 mol), DBU (0.20 ml, 1.34×10−3
mol), ZnCl2 (not dried, 20 mg, 1.47×10−4 mol) and
NaI (22 mg, 1.47×10−4 mol). The resulting suspension
was then stirred at 60° for 3 h. The reaction mixture
was then added to CH2Cl2 (20 ml), washed with satu-
rated NH4Cl (20 ml) and the aqueous layer re-extracted
with another portion of CH2Cl2 (20 ml). The organic
layers were combined, washed once with water (40 ml),
dried and the solvent removed. The crude product was
purified by flash chromatography (eluant:-dichloro-
methane:hexane 2:1 (v/v), Rf 0.37) and then recrys-
tallised from hexane to give colourless needles (150 mg,
70%).
To a solution of 4-bromoanisole (0.30 ml, 2.39
mmol) in piperidine (3 ml) was added Pd(PPh3)4 (138
mg, 1.20×10−4 mol), 1-hexyne (0.30 ml, 2.64 mmol),
wet ZnCl2 (65 mg, 4.79×10−4 mol) and NaI (72 mg,
4.79×10−4 mol). The resulting suspension was then
stirred at 50°C for 16 h. The reaction mixture was then
added to CH2Cl2 (40 ml), washed with saturated NH4Cl
(40 ml) and the aqueous layer re-extracted with another
portion of CH2Cl2 (40 ml). The organic layers were
combined, dried and the solvent removed. The crude
product was passed through a squat column of silica
(eluant:- hexane:dichloromethane 5:1 (v/v), Rf 0.40) and
then further purified by flash chromatography, with the
same solvent system, to give the title compound as a
3.8. GLC experiments
1
colourless oil (412 mg, 92%). H-NMR: 0.94 (t, 2H, J 7
A standard protocol was used for all of the results
summarised in Table 2. To a solution of 4-bromoan-
isole (0.2 ml, 1.6 mmol) in solvent (3 ml) which had
been degassed by the freeze thaw method was added the
metal catalyst (0.054 mmol), 1-hexyne (0.22 ml, 1.92
mmol), ZnCl2 (not dried, 45 mg, 0.32 mmol), NaI (24
mg, 0.16 mol) and n-decane as an internal standard
(0.05 ml, 0.26 mmol). The resulting solution was then
stirred at 60°C and at regular intervals a sample was
withdrawn from the mixture, added to a vial containing
0.5 ml of 5% HCl solution and 0.5 ml of diethyl ether
and shaken. The ether layer was subjected to glc analy-
sis on a 30 m×0.53 mm DB1 Megabore column and
the % conversion of 4-bromoanisole to 1 was deter-
mined by the relative integrations of 1 versus the total
integrations for 1 and 4-bromoanisole relative to the
n-decane standard.
Hz), 1.50 (m, 4H), 2.39 (t, 2H, J 7 Hz), 3.79 (s, 3H),
6.80 (d, 2H, J 9 Hz), 7.30 (d, 2H, J 9 Hz); 13C-NMR:
13.5, 19.0, 21.9, 30.9, 55.0, 80.2 (CꢀC), 88.6 (CꢀC),
113.8, 132.2, 132.8, 159.0; m/z: 188 (M+, 84%), 173
(41), 159 (29), 145 (100), 115 (27); Ir (neat) (wmax, cm−1
2535 (CꢀC).
)
3.7. Dimethyl 5-(2-phenyl-1-ethynyl)isophthalate (2)
3.7.1. Method A
To a solution of dimethyl 5-bromoisophthalate (200
mg, 7.33×10−4 mol) in DMF (3 ml) was added
Pd(PPh3)4 (42 mg, 3.66×10−5 mol), phenylacetylene
(0.09 ml, 8.21×10−4 mol), triethylamine (0.20 ml,
2.76×10−3 mol), ZnCl2 (not dried, 20 mg, 1.47×10−4
mol), NaI (22 mg, 1.47×10−4 mol) and imidazole (10
mg, 1.47×10−4 mol). The resulting suspension was
then stirred at 60° for 16 h. The reaction mixture was
then added to CH2Cl2 (40 ml), washed with saturated
NH4Cl (40 ml) and the aqueous layer re-extracted with
another portion of CH2Cl2 (40 ml). The organic layers
were combined, dried and the solvent removed. The
crude product was then passed through a short column
of silica (eluant:-dichloromethane) to give a fawn solid.
Recrystallisation from hexane gave the title compound
as fine colourless needles (160 mg, 75%). Mp 115-116°;
Anal. Cald for C18H14O4: C, 73.46; H, 4.79. Found: C,
Acknowledgements
We would like to thank the Australian Research
Council for the award of an Australian Postgraduate
Award to P.D.T.
References
1
73.59; H, 4.57; H-NMR: 3.97 (s, 6H), 7.37 (m, 3H),
[1] K. Sonagashira, in: B.M. Trost, I. Fleming (Eds.), Comprehen-
sive Organic Synthesis, vol. 3, Pergamon Press, Oxford, 1991,
pp.521–549.
[2] M. Alami, F. Ferri, G. Linstrumelle, Tetrahedron Lett. 34 (1993)
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[3] J.P. Genet, E. Blart, M. Savignac, Synlett (1992) 715.
[4] J.-F. Nguefack, V. Bolitt, D. Sinou, Tetrahedron Lett. 37 (1996)
5527.
7.54 (m, 2H), 8.36 (d, 2H, J 2 Hz), 8.63 (t, 1H, J 2 Hz);
13C-NMR: 52.4, 87.3 (CꢀC), 91.2 (CꢀC), 122.5, 124.4,
128.5, 128.9, 130.0, 130.9, 131.8, 136.5, 165.7 (CꢁO);
m/z 294 (M+, 89), 263 (44), 235 (14), 220 (21), 176
(61); Ir (nujol mull) (wmax, cm−1) 1722, 1736 (C=O),
2231 (CꢀC).
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3.7.2. Method B
To a solution of dimethyl 5-bromoisophthalate (200
mg, 7.33×10−4 mol) in DMF (3 ml) was added
Pd(PPh3)4 (42 mg, 3.66×10−5 mol), phenylacetylene

224
G.T. Crisp et al. / Journal of Organometallic Chemistry 570 (1998) 219–224
[10] F.R. Hartley, The Chemistry of Platinum and Palladium, Wiley,
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(b) J.S. Moore, T.C. Bedard, J. Am. Chem. Soc. 117 (1995)
10662
[8] D.D. Perrin, W.L.F. Aramarego, D.R. Perrin, Purification of
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[11] T. Ukai, H. Kawazura, Y. Ishii, J.J. Bonnett, J.A. Ibers, J.
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[12] D.R. Coulson, Inorg. Synth. 13 (1972) 121.
[13] Aldrich Catalogue, Aldrich Chemical Company, 1996–1997.
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