The first example of hydrozirconation of alkynes in room temperature ionic liquids

Article abstract of DOI:10.1016/j.jorganchem.2011.04.002

Hydrozirconation of terminal alkynes in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF₆]) at 30 °C gave highly regio- and stereoselectively (E)-vinylzirconium complexes, which underwent a cross-coupling reaction with aryl halides in the presence of Pd(PPh ₃)₄ to afford (E)-1,2-disubstituted ethenes in good to high yields. Our system not only avoids the use of easily volatile THF or CH₂Cl₂ as solvent but also solves the basic problem of palladium catalyst reuse.

Full text of DOI:10.1016/j.jorganchem.2011.04.002

Journal of Organometallic Chemistry 696 (2011) 2685e2688
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Note
The first example of hydrozirconation of alkynes in room temperature
ionic liquids
,
Bin Huang a, Pingping Wang b, Wenyan Hao a, Ming-Zhong Cai a
*
a Department of Chemistry, Jiangxi Normal University, Nanchang 330022, PR China
b Department of Chemistry, Jiujiang University, Jiujiang 332000, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
Hydrozirconation of terminal alkynes in 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]
[PF6]) at 30 ꢀC gave highly regio- and stereoselectively (E)-vinylzirconium complexes, which underwent
a cross-coupling reaction with aryl halides in the presence of Pd(PPh3)4 to afford (E)-1,2-disubstituted
ethenes in good to high yields. Our system not only avoids the use of easily volatile THF or CH2Cl2 as
solvent but also solves the basic problem of palladium catalyst reuse.
Received 27 February 2011
Received in revised form
31 March 2011
Accepted 5 April 2011
Ó 2011 Elsevier B.V. All rights reserved.
Keywords:
Hydrozirconation
Ionic liquid
Palladium catalysis
Cross-coupling reaction
Green synthesis
1. Introduction
palladium-catalyzed addition of diaryl disulfides and diselenides to
terminal alkynes, and hydrostannylation of
a-heteroalkynes and
The development of environmentally friendly synthetic proce-
dures has become a major concern throughout the chemical
industry due to continuing depletion of natural resources and
growing environmental awareness [1e4]. One of the prime concerns
of industry and academia is the search for replacements to delete-
rious molecular solvents used on a large scale, especially those
which are volatile and difficult to contain. Room temperature ionic
liquids, especially those based upon the 1,3-dialkylimidazolium
cation, have attracted growing interest in the last few years [5e9].
Their negligible vapor pressure, ease of handling and potential for
recycling, circumvent many of the problems associated with volatile
organic solvents. Furthermore, their high compatibility with tran-
sition metal catalysts and limited miscibility with common solvents,
enables easy product and catalyst separation with the retention of
the stabilized catalyst in the ionic phase [10]. These and related ionic
liquids have been successfully used as the media in many organic
reactions, which include hydrogenations [11], alkene dimerizations
[12], FriedeleCrafts reactions [13,14], DielseAlder reactions [15e17],
Heck reactions [18e20], Bechmann condensations [21,22], Suzuki
reactions [23e27], BayliseHillman reactions [28,29], Stille reactions
[30] and Sonogashira reactions [31]. Very recently, we have reported
alkynyl esters in room temperature ionic liquids [32,33].
Hydrozirconation is one of the most promising organometallic
technique used in organic synthesis due to some attractive features,
such as the high regioselectivity and stereoselectivity observed with
alkynes [34e37]. These organozirconium intermediates can partici-
pate in cross-coupling reactions [38e40], conjugate and nucleophilic
additions [41,42], and undergo carbonylation [43e45] and haloge-
nation [46e48]. The hydrozirconation reaction of alkynes generally
proceeds at room temperature using THF or CH2Cl2 as the solvent,
however, theTHFor CH2Cl2 iseasily volatile andtoxic. Inaddition, the
cross-coupling reactions of the corresponding alkenylzirconium
complexes obtained by hydrozirconation of alkynes with organic
halides at room temperature are catalyzed by homogeneous palla-
dium or nickel complexes which cannot be recovered and reused.
These disadvantages have so far precluded its practical applications.
In this paper, we describe the first example of hydrozirconation of
alkynes in room temperature ionic liquids. It has been found
that hydrozirconation of terminal alkynes in 1-butyl-3-methyl-
imidazolium hexafluorophosphate ([bmim][PF6]) at 30 ꢀC can
proceed smoothly to afford highly regio- and stereoselectively
(E)-vinylzirconium complexes, which underwent a cross-coupling
reaction with aryl halides in the presence of Pd(PPh3)4 to give (E)-
1,2-disubstituted ethenes in good to high yields. The developed
methodology has important advantages deserving special note.
* Corresponding author. Tel./fax: þ86 791 8120388.
E-mail address: caimzhong@163.com (M.-Z. Cai).
0022-328X/$ e see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2011.04.002

2686
B. Huang et al. / Journal of Organometallic Chemistry 696 (2011) 2685e2688
2. Experimental
2.2.6. (E)-1-(4-Chlorophenyl)-1-octene, 3f [52]
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.62-7.59 (m, 2H),
2.1. General remarks
7.10-7.08 (m, 2H), 6.33 (d, J ¼ 16.0 Hz, 1H), 6.22 (dt, J ¼ 16.0, 6.8 Hz,
1H), 2.24-2.17 (m, 2H), 1.49-1.42 (m, 2H), 1.38-1.25 (m, 6H), 0.91 (t,
All chemicals were of reagent grade and used as purchased. All
products were characterized by comparison of their spectra and
physical data with authentic samples. IR spectra were determined
on a PerkineElmer 683 instrument. 1H NMR spectra were recorded
on a Bruker AC-P400 (400 MHz) spectrometer with TMS as an
internal standard in CDCl3 as solvent. 13C NMR spectra were
recorded on a Bruker AC-P400 (100 MHz) spectrometer in CDCl3 as
solvent. Microanalyses were measured using a Yanaco MT-3 CHN
microelemental analyzer. Melting points are uncorrected.
J ¼ 7.0 Hz, 3H) ppm. IR (film):
n
¼ 2957, 2927, 1707, 1594, 1490, 1091,
964, 809 cmꢁ1
.
2.2.7. (E)-1-Phenyl-3-methoxypropene, 3g [53]
Colorless oil. 1H NMR (400 MHz, CDCl3):
6.61 (d, J ¼ 16.0 Hz, 1H), 6.28 (dt, J ¼ 16.0, 6.0 Hz, 1H), 4.09 (d,
J ¼ 6.0 Hz, 2H), 3.39 (s, 3H) ppm. IR (film): ¼ 2926, 2821, 1658,
1599, 1449, 1191, 1121, 1029, 967, 743 cmꢁ1
d
¼ 7.40-7.22 (m, 5H),
n
.
2.2.8. (E)-1-(4-Chlorophenyl)-3-methoxypropene, 3h[54]
Colorless oil. 1H NMR (400 MHz, CDCl3):
¼ 7.33-7.25 (m, 4H),
6.56 (d, J ¼ 16.0 Hz, 1H), 6.25 (dt, J ¼ 16.0, 6.0 Hz, 1H), 4.08 (d,
J ¼ 6.0 Hz, 2H), 3.39 (s, 3H) ppm. IR (film): ¼ 2925, 2823, 1683,
1593, 1491, 1191, 1090, 1012, 968, 846, 796 cmꢁ1
2.2. General procedure for the hydrozirconation/cross-coupling
tandem reaction of terminal alkynes with aryl halides in [bmim]
[PF6]
d
n
.
In a 20 mL two-necked round-bottom flask, equipped with
a magnetic stirrer bar, was placed 2 mL of [bmim][PF6]. The flask
was then degassed under reduced pressure at room temperature
for 1 h, and argon gas was then introduced. To the ionic liquid were
added terminal alkyne (1 mmol) and Cp2Zr(H)Cl (1.1 mmol), and
the resulting mixture was stirred at 30 ꢀC for 1 h. Then aryl halide
(1 mmol) and Pd(PPh3)4 (0.05 mmol) were added and the mixture
was stirred at 60e80 ꢀC for 12 h. Product was extracted from the
reaction mixture by the addition of light petroleum ether (8 mL),
followed by decanting off a petroleum ether solution of the prod-
ucts. This was repeated two additional times. After evaporation, the
residue was purified by flash chromatography on silica gel using
light petroleum ether as the eluent.
2.2.9. (E)-1-(4-Methylphenyl)-2-phenylethene, 3i
White solid. 118e119 ꢀC (lit [55]. m.p. 120 ꢀC). 1H NMR
(400 MHz, CDCl3):
7.35 (t, J ¼ 7.6 Hz, 2H), 7.28-7.22 (m, 1H), 7.16 (d, J ¼ 8.4 Hz, 2H), 7.07
(d, J ¼ 2.4 Hz, 2H), 2.36 (s, 3H) ppm. IR (KBr): ¼ 3024, 2918, 1643,
1595, 1511, 1448, 970, 809, 690 cmꢁ1
d
¼ 7.50 (d, J ¼ 7.2 Hz, 2H), 7.41 (d, J ¼ 8.0 Hz, 2H),
n
.
2.2.10. (E)-1,2-Diphenylethene, 3j
White solid. 124 ꢀC (lit [56]. m.p. 124 ꢀC). 1H NMR (400 MHz,
CDCl3):
¼ 7.53-7.51 (m, 4H), 7.38-7.33 (m, 4H), 7.28-7.23 (m, 2H),
7.11 (s, 2H) ppm. IR (KBr):
¼ 3019, 1597, 1576, 1495, 1451, 962, 765,
692 cmꢁ1
d
n
.
2.2.1. (E)-1-(4-Methoxyphenyl)-1-hexene, 3a[49]
2.2.11. (E)-1-(4-Chlorophenyl)-2-phenylethene, 3k
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.27 (d, J ¼ 8.4 Hz,
White solid. 127e128 ꢀC (lit [57]. m.p. 129 ꢀC). 1H NMR
2H), 6.83 (d, J ¼ 8.4 Hz, 2H), 6.32 (d, J ¼ 16.0 Hz, 1H), 6.09 (dt,
(400 MHz, CDCl3):
7.38-7.27 (m, 5H), 7.07 (d, J ¼ 2.8 Hz, 2H) ppm. IR (KBr):
1643, 1588, 1494, 1448, 1090, 966, 817, 691 cmꢁ1
d
¼ 7.50 (d, J ¼ 7.2 Hz, 2H), 7.44 (d, J ¼ 8.8 Hz, 2H),
J ¼ 16.0, 7.2 Hz, 1H), 3.80 (s, 3H), 2.22-2.16 (m, 2H), 1.46-1.34 (m,
n
¼ 3019,
4H), 0.93 (t, J ¼ 7.4 Hz, 3H) ppm. IR (film):
n
¼ 2957, 2929,1608,1511,
.
1248, 1174, 1038, 965, 804 cmꢁ1
.
2.2.12. (E)-1-(4-Methoxyphenyl)-2-phenylethene, 3l
White solid. 134e135 ꢀC (lit [58]. m.p. 136 ꢀC). 1H NMR
(400 MHz, CDCl3):
2.2.2. (E)-1-(4-Chlorophenyl)-1-hexene, 3b [49]
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.59 (d, J ¼ 8.4 Hz,
d
¼ 7.49 (d, J ¼ 7.6 Hz, 2H), 7.45 (d, J ¼ 8.4 Hz, 2H),
2H), 7.07 (d, J ¼ 8.4 Hz, 2H), 6.31 (d, J ¼ 16.0 Hz, 1H), 6.20 (dt,
J ¼ 16.0, 7.2 Hz, 1H), 2.21-2.17 (m, 2H), 1.45-1.34 (m, 4H), 0.92 (t,
7.34 (t, J ¼ 7.6 Hz, 2H), 7.23 (t, J ¼ 7.6 Hz,1H), 7.07 (d, J ¼ 16.4 Hz,1H),
6.97 (d, J ¼ 16.4 Hz, 1H), 6.90 (d, J ¼ 8.8 Hz, 2H), 3.83 (s, 3H) ppm. IR
J ¼ 7.2 Hz, 3H) ppm. IR (film):
n
¼ 2957, 2927, 1650, 1593, 1470, 1091,
(KBr):
n
¼ 3050, 1603, 1500, 1252, 1170, 968, 820, 750 cmꢁ1
.
1005, 966, 809 cmꢁ1
.
2.2.13. (E)-1-(4-Chlorophenyl)-4-methoxy-1-butene, 3m
Colorless oil. 1H NMR (400 MHz, CDCl3):
2.2.3. (E)-1-(4-Methoxyphenyl)-1-octene, 3c [50]
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.11-7.06 (m, 2H),
d
¼ 7.28-7.25 (m, 2H),
6.23 (d, J ¼ 16.0 Hz, 1H), 6.04 (dt, J ¼ 16.0, 7.2 Hz, 1H), 3.33 (t,
6.85-6.82 (m, 2H), 6.32 (d, J ¼ 16.0 Hz, 1H), 6.08 (dt, J ¼ 16.0, 7.0 Hz,
J ¼ 6.8 Hz, 2H), 3.19 (s, 3H), 2.33-2.28 (m, 2H) ppm. 13C NMR
1H), 3.80 (s, 3H), 2.21-2.15 (m, 2H), 1.47-1.42 (m, 2H), 1.36-1.23 (m,
(100 MHz, CDCl3):
d
¼ 135.97, 132.54, 130.38, 128.57, 127.80, 127.24,
6H), 0.89 (t, J ¼ 6.8 Hz, 3H) ppm. IR (film):
n
¼ 2957, 2925, 1608,
72.07, 58.72, 33.40 ppm. IR (film):
n
¼ 3028, 2926, 1652, 1594, 1491,
1511, 1250, 1174, 1039, 964, 805 cmꢁ1
.
1119, 1093, 967, 806 cmꢁ1. Anal. Calcd. for C11H13OCl: C, 67.16; H,
6.66. Found: C, 66.89; H, 6.81.
2.2.4. (E)-1-Phenyl-1-octene, 3d [50]
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.36-7.16 (m, 5H),
2.2.14. (E)-1-(4-Methoxyphenyl)-2-cyclopropylethene, 3n[59]
6.37 (d, J ¼ 16.0 Hz, 1H), 6.22 (dt, J ¼ 16.0, 6.8 Hz, 1H), 2.23-2.17 (m,
White solid. 47e48 ꢀC 1H NMR (400 MHz, CDCl3):
d
¼ 7.23 (d,
2H), 1.48-1.42 (m, 2H), 1.38-1.25 (m, 6H), 0.89 (t, J ¼ 6.8 Hz, 3H)
J ¼ 8.8 Hz, 2H), 6.82 (d, J ¼ 8.8 Hz, 2H), 6.42 (d, J ¼ 15.6 Hz, 1H), 5.59
(dd, J ¼ 15.6, 8.8 Hz, 1H), 3.79 (s, 3H), 1.57-1.51 (m, 1H), 0.82-0.77
ppm. IR (film):
n
¼ 2956, 2926, 1707, 1598, 1449, 962, 742, 692 cmꢁ1
.
(m, 2H), 0.50-0.46 (m, 2H) ppm. IR (KBr):
n
¼ 2955, 1642, 1607, 1567,
2.2.5. (E)-1-(4-Methylphenyl)-1-octene, 3e [51]
Colorless oil. 1H NMR (400 MHz, CDCl3):
1512, 1163, 1074, 955, 861 cmꢁ1
.
d
¼ 7.23 (d, J ¼ 7.6 Hz,
2H), 7.09 (d, J ¼ 7.6 Hz, 2H), 6.34 (d, J ¼ 16.0 Hz, 1H), 6.15 (dt,
J ¼ 16.0, 7.2 Hz, 1H), 2.31 (s, 3H), 2.21-2.15 (m, 2H), 1.47-1.41 (m,
2H), 1.38-1.24 (m, 6H), 0.89 (t, J ¼ 7.2 Hz, 3H) ppm. IR (film):
2.2.15. (E)-1-(2-thienyl)-2-cyclopropylethene, 3o
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.04 (d, J ¼ 5.2 Hz,
1H), 6.93-6.90 (m, 1H), 6.82 (d, J ¼ 3.6 Hz, 1H), 6.59 (d, J ¼ 15.6 Hz,
n
¼ 2957, 2925, 1603, 1597, 1448, 963, 807 cmꢁ1
.
1H), 5.59 (dd, J ¼ 15.6, 9.2 Hz, 1H), 1.57-1.48 (m, 1H), 0.83-0.78 (m,

B. Huang et al. / Journal of Organometallic Chemistry 696 (2011) 2685e2688
2687
2H), 0.51-0.48 (m, 2H) ppm. 13C NMR (100 MHz, CDCl3):
d
¼ 143.07,
R
H
H
R
H
H
Cp2Zr(H)Cl
ArX, 5mol%Pd(PPh
)
3 4
R
134.85, 127.27, 123.69, 122.65, 120.78, 14.41, 7.32 ppm. IR (film):
[Bmim][PF6], 60-80 o
C
Ar
[Bmim][PF6]
30 oC, 1h
ZrCp2Cl
n
¼ 3081, 3005, 2925, 1644, 1428, 1207, 1043, 949, 692 cmꢁ1. Anal.
3
2
1
Calcd. for C9H10S: C, 71.95; H, 6.71. Found: C, 71.67; H, 6.82.
Scheme 1.
2.2.16. (E)-3,3-Dimethyl-1-(4-cyanophenyl)-1-butene, 3p
White solid. 50e51 ꢀC 1H NMR (400 MHz, CDCl3):
d
¼ 7.58 (d,
The hydrozirconation/palladium-catalyzed cross-coupling tand-
J ¼ 8.0 Hz, 2H), 7.43 (d, J ¼ 8.4 Hz, 2H), 6.40 (d, J ¼ 16.0 Hz, 1H), 6.30
(d, J ¼ 16.0 Hz, 1H), 1.13 (s, 9H) ppm. 13C NMR (100 MHz, CDCl3):
em reaction of a variety of terminal alkynes with Cp2Zr(H)Cl and
various aryl halides was investigated (Scheme 1), and the experi-
mental results are summarized in Table 2. As shown in Table 2,
hydrozirconation reactions of a variety of terminal alkynes with
Cp2Zr(H)Cl in [bmim][PF6] at 30 ꢀC proceeded smoothly to give
highly regio- and stereoselectively the corresponding (E)-vinyl-
zirconium complexes intermediates 2, which can not be isolated
due to being sensitive to moisture and underwent directly a cross-
coupling reaction with various aryl iodides in the presence of 5 mol
% of Pd(PPh3)4 to afford stereoselectively (E)-1,2-disubstituted
ethenes in high yields. Strongly electron-donating and electron-
withdrawing groups on aryl iodides were well tolerated.
Hydrozirconation reactions of cyclopropylethyne and bulky
3,3-dimethylbut-1-yne also proceeded smoothly in [bmim][PF6] at
30 ꢀC (entries 16e19). The heteroaryl iodides such as 2-iodothio-
phene could be coupled with (E)-vinylzirconium complexes inter-
mediates 2 to afford the corresponding (E)-1,2- disubstituted ethene
in high yield (entry 17). As expected, the reactivity of aryl bromides
was lower than thatof aryl iodides. The cross-couplingreaction of the
intermediates 2 with aryl bromides in the presence of 5 mol% of
Pd(PPh3)4 was slow at 60 ꢀC, affording the corresponding coupled
products in moderate yields after 12 h (entries 20, 21). However, the
palladium catalyzed cross-coupling reaction of the intermediates 2
with a variety of aryl bromides proceeded smoothly at 80 ꢀC to afford
the corresponding coupled products in good yields after 12 h (entries
22e27). The substituent effects in the aryl iodides appeared to be less
significant than in the aryl bromides and the reactivity of aryl
d
¼ 145.93, 142.66, 132.35, 126.53, 123.44, 119.26, 109.85, 33.78,
29.34 ppm. IR (KBr):
n
¼ 2952, 2227, 1645, 1604, 1364, 1174, 1071,
969, 863, 808 cmꢁ1. Anal. Calcd. for C13H15N: C, 84.28; H, 8.16.
Found: C, 83.97; H, 7.89.
2.2.17. (E)-3,3-Dimethyl-1-(3-trifluoromethylphenyl)-1-butene, 3q
Colorless oil. 1H NMR (400 MHz, CDCl3):
d
¼ 7.60 (s, 1H), 7.52 (d,
J ¼ 8.0 Hz, 1H), 7.46-7.39 (m, 2H), 6.33 (s, 2H), 1.13 (s, 9H) ppm. 13C
NMR (100 MHz, CDCl3):
d
¼ 143.77, 138.83, 130.81 (q), 129.24,
128.86, 125.61, 123.49, 123.27, 122.66, 33.54, 29.45 ppm. IR (film):
n
¼ 2963, 2868, 1649, 1593, 1334, 1165, 1128, 968, 793, 697 cmꢁ1
.
Anal. Calcd. for C13H15F3: C, 68.41; H, 6.62. Found: C, 68.18; H, 6.43.
3. Results and discussion
As a suitable solvent for the hydrozirconation of alkynes, the
moisture stable and readily available 1-butyl-3-methylimidazolium
hexafluorophosphate ([bmim][PF6]) was chosen. Initially, to deter-
mine the optimum cross-coupling reaction conditions, the hydro-
zirconation/transition metal catalyzed cross-coupling tandem
reaction of 1-hexyne with Cp2Zr(H)Cl and 4-iodoanisole was
examined, the results are summarized in Table 1. It was found that
among the transition metal catalysts tested, Pd(PPh3)4 proved to be
the most efficient. For the temperatures evaluated [30, 40, 60, and
80 ꢀC], 60 ꢀC gave the best result. Increasing the amount of palla-
dium catalyst could shorten the cross-coupling reaction time, but
didn’t increase the yield of (E)-1-(4-methoxyphenyl)-1-hexene
(entry 11). The low palladium concentration usually led to a long
period of reaction, which was consistent with our experimental
results (entry 8). Taken together, good result was obtained when the
cross-coupling reaction was carried out with 5 mol % of Pd(PPh3)4 in
[bmim][PF6] at 60 ꢀC (entry 9).
Table 2
Synthesis of (E)-1,2-disubstituted ethenes.a
Entry
R
ArX
Temp (ꢀC)
Product
Yield (%)b
1
2
3
4
5
6
7
8
n-C4H9
n-C4H9
n-C6H13
n-C6H13
n-C6H13
n-C6H13
CH3OCH2
CH3OCH2
Ph
4eCH3OC6H4I
4eClC6H4I
4eCH3OC6H4I
PhI
4eCH3C6H4I
4eClC6H4I
PhI
4eClC6H4I
4eCH3C6H4I
PhI
4eClC6H4I
4eCH3OC6H4I
PhI
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
60
80
80
80
80
80
80
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3i
3l
3m
3n
3o
3p
3q
3b
3d
3b
3a
3g
3h
3i
85
90
86
87
84
89
83
84
89
85
87
84
86
80
83
87
81
85
83
54
48
85
78
79
84
77
83
Table 1
Cross-coupling of (E)-alkenylzirconium complex with 4-iodoanisole under the
various reaction conditions.a
9
n-Bu
H
n-Bu
H
Cp Zr(H)Cl
4-CH OC H I
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
Ph
Ph
Ph
n-Bu
[Bmim][PF ], Catalyst
[Bmim][PF ]
30 C, 1h
H
ZrCp Cl
H
C H OCH -4
4eCH3C6H4
4eCH3OC6H4
CH3OCH2CH2
cyclopropyl
cyclopropyl
teC4H9
teC4H9
n-C4H9
n-C6H13
n-C4H9
n-C4H9
CH3OCH2
CH3OCH2
Ph
PhI
4eClC6H4I
4eCH3OC6H4I
C4H3SI
4eNCC6H4I
3eCF3C6H4I
4eClC6H4Br
PhBr
4eClC6H4Br
4eCH3OC6H4Br
PhBr
4eClC6H4Br
4eCH3C6H4Br
4eClC6H4Br
Entry
Catalyst
Temp. (ꢀC)
Time (h)
Yield (%)b
1
2
3
4
5
6
7
8
Ni(PPh3)4 (2 mol%)
Ni(PPh3)4 (2 mol%)
Ni(PPh3)4 (2 mol%)
Ni(PPh3)4 (5 mol%)
Ni(PPh3)4 (5 mol%)
Pd(PPh3)4 (2 mol%)
Pd(PPh3)4 (2 mol%)
Pd(PPh3)4 (2 mol%)
Pd(PPh3)4 (5 mol%)
Pd(PPh3)4 (5 mol%)
Pd(PPh3)4 (10 mol%)
PdCl2(PPh3)2 (5 mol%)
30
40
60
60
80
30
40
60
60
80
60
60
24
24
24
24
24
24
24
24
12
12
8
0
0
47
54
52
0
0
66
85
81
83
61
9
10
11
12
Ph
3k
14
a
Reactions were performed with terminal alkyne (1 mmol), Cp2Zr(H)Cl
(1.1 mmol) in [bmim][PF6] (2 mL) at 30 ꢀC under argon for 1 h, then with aryl halide
(1 mmol) and Pd(PPh3)4 (0.05 mmol) for 12 h.
a
Reaction was performed with 1-hexyne (1 mmol), Cp2Zr(H)Cl (1.1 mmol) in
[bmim][PF6] (2 mL) at 30 ꢀC under argon for 1 h, then with 4-iodoanisole (1 mmol).
b
b
Isolated yield based on 4-iodoanisole used.
Isolated yield based on the aryl halide used.

2688
B. Huang et al. / Journal of Organometallic Chemistry 696 (2011) 2685e2688
Table 3
Acknowledgment
Ionic liquid and palladium catalyst recyclinga
4-ClC6H4I
5 mol% Pd(PPh3)4
We thank the National Natural Science Foundation of China
(Project No.20862008) and the Natural Science Foundation of
Jiangxi Province (Project No. 2008GQH0034).
n-Bu
n-Bu
H
H
Cp2Zr(H)Cl
n-Bu
[Bmim][PF6]
30 oC, 1h
[Bmim][PF6]
60 oC, 12 h
ZrCp2Cl
H
H
C6H4Cl-4
References
Cycle
Yieldb (%)
Cycle
Yieldb (%)
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