A lutidine-bridged bis-perimidinium salt: Synthesis and application as a precursor in palladium-catalyzed cross-coupling reactions

Article abstract of DOI:10.1002/adsc.200800768

A novel lutidine-bridged bis-perimidini-um dibromide 3 was synthesized in quantitative yield from cheap commercial starting materials. The bisylidene prepared therefrom in situ upon deproto-nation is a potent precatalyst in palladium-catalyzed Heck and Suzuki cross-coupling reactions under aerobic conditions, and is efficient even with a ppm scale catalyst loading. Its stronger o-donor character is held to be responsible for its superior catalytic performance compared with imidazole- and benz-imidazole-based analogues bearing the same skeleton precursors.

Full text of DOI:10.1002/adsc.200800768

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DOI: 10.1002/adsc.200800768
A Lutidine-Bridged Bis-Perimidinium Salt: Synthesis and
Application as a Precursor in Palladium-Catalyzed
Cross-Coupling Reactions
Tao Tu,a,* Jagadeesh Malineni,a Xiaoling Bao,a and Karl Heinz Dçtza,*
a
Kekulꢀ-Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, 53121, Bonn,
Germany
Fax : (+49)-228-73-5813; e-mail: doetz@uni-bonn.de or tao.tu@uni-bonn.de
Received: December 11, 2008; Revised: March 23, 2009; Published online: May 5, 2009
Dedicated to Prof. Armin de Meijere on the occasion of his 70th birthday.
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/adsc.200800768.
Abstract: A novel lutidine-bridged bis-perimidini-
um dibromide 3 was synthesized in quantitative
yield from cheap commercial starting materials. The
bisylidene prepared therefrom in situ upon deproto-
nation is a potent precatalyst in palladium-catalyzed
Heck and Suzuki cross-coupling reactions under
aerobic conditions, and is efficient even with a ppm
scale catalyst loading. Its stronger s-donor character
is held to be responsible for its superior catalytic
performance compared with imidazole- and benz-
salts.[4a,d] Therefore, we started to exploit the potential
of perimidine-based NHCs in transition metal-cata-
lyzed transformations, an approach which has been
paid less attention to so far.[4b,c]
Due to their robustness, activity and variability,
pincer-type ligands and their metal complexes attract
increasing interest in catalysis, the development of
molecular devices and soft matter.[5] As widely uti-
lized pincer skeletons, lutidine/pyridine-bridged
NHCs and their metal complexes proved to efficiently
À
À
A
catalyze C C and C N bond formation as well as
olefin metathesis.[5b–d,6] Recently, we reported that bis-
imidazol-2-ylidene palladium pincer complexes and
their benzo analogues efficiently gelate a wide variety
of organic solvents and ionic liquids.[7] We disclosed
ton precursors.
Keywords: carbenes; Heck reaction; palladium;
perimidinium salts; Suzuki coupling
N-Heterocyclic carbenes (NHCs) are known as strong
s-donor and weak p-acceptor ligands, and as such
their metal complexes are widely applied in catalysis
and material sciences.[1] They increasingly compete
successfully with phosphines in terms of compatibility
with aerobic conditions, thermostability and environ-
mental friendliness.[2] In this respect, ylidenes derived
from five-membered heterocycles such as imidazoli-
um (1) and benzimidazolium salts (2), have been de-
veloped as typical skeletons of stable NHCs, and have
been successfully applied as ligands in transition
metal-catalyzed reactions (Scheme 1).[1–3] Ylidenes de-
rived from perimidinium salts (3) provide arene-fused
six-membered heterocycles and, thus, represent a
novel type of NHC framework which results in a
stronger s-donor ability in comparison with N-hetero-
Scheme 1. Lutidine-bridged imidazole-, benzimidazole- and
cyclic carbenes derived from (benz)imidazolium perimidine-based NHC precursors 1–3.
Adv. Synth. Catal. 2009, 351, 1029 – 1034
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Tao Tu et al.
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Scheme 2. Synthesis of lutidine-bridged bis-perimidinium dibromide 3.
their high catalytic activities in homogeneous (such as
Heck and Suzuki coupling reactions with a ppm scale
catalyst loading)[8] and heterogeneous (Michael addi-
tion in the gel state)[7b] transformations, and also re-
ported on bis-benzimidazolium salts – precursors of
the pincer ligands – as efficient gelators for organic,
especially alcoholic, solvents and catalysts for phase-
Scheme 3. Cross-coupling of halobenzenes and n-butyl acry-
late catalyzed by bis-perimidinium dibromide 3/Pd(OAc)2
[catalyst prepared in situ from equimolar amounts of 3 and
Pd(OAc)2].
transfer alkylations.[9] In an extension of this work, we
incorporated the perimidine ring, a stronger s-donor
with an increased p-size in comparison to the (benz)-
ACHTUNGTRENNUNG
AHCTUNGTRENNUNG
ACHTUNGTRENNUNGimidazole heterocycles, into pincer-type NHCs in
order to explore their potential in catalysis and soft
materials. We now report on a novel lutidine-bridged
bis-perimidinium salt which is easily accessible from um complex intermediate formed in situ tolerates
cheap commercial starting materials, and on its role higher temperatures and the presence of air and mois-
as a precatalyst in palladium-catalyzed Heck and ture.
Suzuki cross-coupling reactions.
If the reaction time is extended to 42 h under these
Lutidine-bridged bis-perimidinum dibromide 3 is standard conditions, the catalyst loading can be dra-
accessible as a bright yellow solid in almost quantita- matically reduced to 2 ppm resulting in only moder-
tive yield by N-alkylation of N-butylperimidine 4 with ately decreased yields of n-butyl cinnamate 5a (82%
2,6-bis(bromomethyl)pyridine in
a
sealed tube for iodobenzene and 71% for bromobenzene; Table 1,
(Scheme 2). N-Butylperimidine 4 was obtained in entries 1 and 2). In order to investigate the scope of
86% isolated yield by dropwise addition of n-butyl the protocol and, in particular, the electronic and
bromide to a solution of perimidine – deprotonated steric implications of the substrates, we tested a varie-
by oil-free NaH in THF at room temperature – and ty of iodoarenes under our 2 ppm catalyst loading
subsequent warming of the mixture to reflux.[10]
standard conditions (Table 1). For monosubstituted
Within our programme aiming at the development iodoarenes, the catalyst tolerates additional substitu-
of NHCs and Fischer carbenes towards application in ents with different electronic and steric properties
catalysis and soft material sciences,[7–9,11] we addressed and allowed for moderate to good isolated yields of
the role of a strong s-donor in a six-membered het- biphenyl derivatives 5b–i (Table 1, entries 3–11).
erocycle on the catalytic activity and tested bis-peri- Compared with their meta-isomer the coupling of
midinium salt 3 in palladium-catalyzed Heck and ortho- and para-iodotoluenes resulted in higher con-
Suzuki cross-coupling reactions. To simplify the cata- versions and yields (88% and 92% versus 74%) and
lytic protocol we aimed at an in situ formation of the in turnover numbers (TON) up to 4.62ꢂ105 (Table 1,
catalyst[4d,6d] and used bis-perimidinium dibromide 3 entries 3–5); a lower yield and TON were again ob-
in the presence of equimolar amounts of PdACTHNUTRGNEUNG
(OAc)2. served with para-bromotoluene (77%, 3.85ꢂ105;
The Heck coupling of aromatic halides and n-butyl Table 1, entry 6). Donor-substitution increases the
acrylate was chosen as a model reaction. A 2 mol% yield and TON of the ß-aryl acrylate as shown for
catalyst loading [equimolar amounts of 3 and Pd- para-iodoanisole (4.51ꢂ105, Table 1, entry 7). Moder-
ACHTUNGTRENNUNG(OAc)2] in 1-methyl-2-piperidone (NMP) at 1408C ate yields and TONs result from acceptor and sterical-
using K2CO3 as a base gave the best results for iodo- ly more demanding substitution patterns (Table 1, en-
benzene (98% after 60 min) (Scheme 3). A slightly tries 8–12). 1-Iodo-3,5-dimethylbenzene still afforded
lower yield was observed for bromobenzene (93% a 62% yield (Table 1, entry 12), whereas no coupling
after 90 min). Identical results were obtained under product at all, even at extended reaction times, was
aerobic conditions indicating that the pincer palladi- observed for the strong acceptor analogue 1-iodo-3,5-
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A Lutidine-Bridged Bis-Perimidinium Salt: Synthesis and Application
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Table 1. Heck cross-coupling reactions of haloarenes with n-butyl acrylate catalyzed by lutidine-bridged N-heterocyclic di-
bromides 1–3 and Pd
(OAc)2.[a]
AHCTUNGTRENNUNG
Entry
ArX
Salt
Product
Yield (%)[b]
TON
1
2
3
4
5
6
7
8
Iodobenzene
Bromobenzene
2-Iodotoluene
3-Iodotoluene
4-Iodotoluene
4-Bromotoluene
4-Iodoanisole
4-Iodoacetophenone
1-Iodo-2-(trifluoromethyl)benzene
1-Iodo-4-(trifluoromethyl)benzene
1-Iodonaphthalene
1-Iodo-3,5-dimethylbenzene
4-Iodotoluene
3
3
3
3
3
3
3
3
3
3
3
3
2
1
5a
5a
5b
5c
5d
5d
5e
5f
5g
5h
5i
82
71
88
74
92
77
90
69
71
73
73
62
69
46
4.10ꢂ105
3.55ꢂ105
4.41ꢂ105
3.71ꢂ105
4.62ꢂ105
3.85ꢂ105
4.51ꢂ105
3.45ꢂ105
3.57ꢂ105
3.63ꢂ105
3.66ꢂ105
3.08ꢂ105
3.44ꢂ105
2.30ꢂ105
9
10
11
12
13
14
5j
5d
5d
4-Iodotoluene
[a]
Reaction conditions: 2 mmol haloarene, 2.4 mmol n-butyl acrylate and 3 mmolK2CO3 in 3 mL NMP at 1408C for 42 h
with 2 ppm catalyst [prepared in situ from equimolar amounts of lutidine-bridged N-heterocyclic dibromide and
PdACHTUNGTRENNUNG
[b]
bis(trifluoromethyl)benzene indicating a pronounced thermal stability of the catalyst we synthesized the
stereoelectronic effect. bis-perimidinylidene pincer palladium complex under
A comparison between the lutidine-bridged bis-per- the conditions applied in the catalytic reactions but in
imidinium dibromide 3 and its imidazole and benzimi- the absence of any substrate (for details, see Support-
dazole analogues (1 and 2, R=n-Bu and X=Br) sug- ing Information).
gests that their catalytic performance increases with
The bis-perimidinium salt 3 is equally effective in
the s-donor ability of the NHC ligand present in the Suzuki coupling reactions and allows for remarkably
active palladium catalyst. Under the standard condi- low catalyst loading (Table 2). Under similar condi-
tions of 2 ppm catalyst loading applied to the coupling tions as applied for the Heck cross-coupling, but with
of para-iodotoluenes with n-butyl acrylate, the less ef- a catalyst loading reduced to 0.2 mol%, bromoben-
ficient benzimidazolium (2) and imidazolium (1) ana- zene reacted with phenylboronic acid to give biphenyl
logues afford reduced yields of 69 and 46%, respec- 6a in a 95% yield after 6 h (Table 2, entry 1); reducing
tively (Table 1, entries 13 and 14). Major amounts of the catalyst concentration by another order of magni-
starting materials were recovered in the both cases, tude still resulted in an 82% yield (Table 2, entry 2).
strictly contrasting the full conversion observed with A study of the amount of catalyst required for a syn-
bis-perimidinium dibromide 3 as precatalyst (Table 1, thetically useful protocol was carried out for a selec-
entry 5). These results underline the role of s-dona- tion of donor- and acceptor-substituted iodoarenes.
tion of the NHC ligand in palladium catalysis.
In order to characterize the nature of the catalytic time is demonstrated for iodobenzene (Table 2, en-
species generated from Pd(OAc)2 and salt 3 in situ we tries 3–5). With a catalyst loading of 0.02 mol%, 92%
The balance of catalyst concentration and reaction
AHCTUNGTRENNUNG
performed the mercury test which has been reported of biphenyl 6a was isolated after warming a NMP so-
to allow a discrimination between molecular and lution at 1408C for 5 h (Table 2, entry 3). To secure a
nanoparticle/colloidal catalysis.[12–15] A set of reactions similar high yield the amount of catalyst can be even
using iodobenzene, butyl acrylate, 1 mol% catalyst in reduced to 5 ppm if the reaction is allowed to proceed
the presence of excess mercury (with respect to the for 48 h. A further reduction of the catalyst loading to
palladium source) added after 0, 15, 30 and 45 min 2 ppm resulted in a 63% yield of 6a after 36 h and a
was run at 1408C in NMP and monitored by TLC and TON of 3.15ꢂ105 while a considerable amount of
GC-MS. In all four cases a full conversion to butyl starting material was recovered (Table 1, entry 4).
cinnamate and an isolated yield of 98% identical with Since running the reactions in NMP to 1408C for 48 h
that known for the reaction without mercury was ob- in the presence of 5 ppm catalyst turned out to be the
served suggesting a molecular catalytically active spe- overall optimum conditions they were applied to a
cies containing the CNC ligand similar to that previ- comparative study demonstrating the scope of the
ously reported by Crabtree.[15] To demonstrate the protocol and influences of electronic and steric prop-
Adv. Synth. Catal. 2009, 351, 1029 – 1034
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Table 2. Suzuki-coupling of haloarenes with phenyl boronic acid catalyzed by lutidine-bridged dibromides 1–3 and
Pd
(OAc)2.[a]
ACHTUNGTRENNUNG
Entry
ArX
Salt
Catalyst [mol%]
Time [h]
Product
Yield[c] [%]
TON
1
2
3
4
5
6
7
8
Bromobenzene
Bromobenzene
Iodobenzene
Iodobenzene
Iodobenzene
2-Iodotoluene
3-Iodotoluene
4-Iodotoluene
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
2
1
0.2
0.02
0.02
6
6
5
6a
6a
6a
6a
6a
6b
6c
6d
6e
6f
6g
6h
6i
95
82
92
63
475
4120
4600
0.0002
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
0.0005
36
48
48
48
48
48
48
48
48
48
48
48
48
48
48
3.15ꢂ105
1.83ꢂ105
1.79ꢂ105
1.48ꢂ105
1.87ꢂ105
1.77ꢂ105
1.43ꢂ105
1.64ꢂ105
1.66ꢂ105
1.53ꢂ105
1.45ꢂ105
1.34ꢂ105
1.22ꢂ105
1.41ꢂ105
9.72ꢂ104
91 (81[d])
89
74
93
89
71
82
83
76
73
67
61
70
49
9
4-Iodoanisole
10
11
12
13
14
15
16
17
18
4-Iodoacetophenone
1-Iodo-4-(trifluoromethyl)benzene
1-Iodo-2-(trifluoromethyl)benzene
1-Fluoro-2-iodobenzene
1-Iodonaphthalene
2-Iodopyridine
1-Iodo-3,5-dimethylbenzene
4-Iodotoluene
4-Iodotoluene
6j
6k
6l
6d
6d
[a]
Reaction conditions: 2 mmol haloarene, 2.2 mmol phenyl boronic acid and 2.4 mmolK2CO3 in 3 mL NMP at 1408C.
Catalyst prepared in situ from equimolar amounts of 1–3 and PdACTHNUTRGNEUNG(OAc)2.
Isolated yield.
Reaction for 36 h.
[b]
[c]
[d]
erties of the substrates. As observed for the Heck re- trend observed for the Heck reaction that the effi-
actions (vide supra) ortho- and para-iodotoluenes are ciency of the precatalyst increases with the s-donor
more reactive (yields of 89 and 93% for 6b and 6d, re- ability of the respective NHC ligand formed in the
spectively) than their meta-isomer 6c (74%, Table 2, presence of base and attached to palladium in the
entries 6–8). The examples outlined in Table 2, en- active catalyst.
tries 9–14, are characterized by moderate to good
In conclusion, lutidine-bridged bis-perimidinium
yields (71–89%) and indicate that no obvious elec- bromide 3 which is accessible from cheap commercial
tronic or steric effects are operative allowing for a starting materials in a nearly quantitative reaction is
rather broad monosubstitution pattern of the biaryl an efficient precatalyst in combination with palladium
target molecules. The coupling reactions of 2-iodopyr- acetate for Heck and Suzuki cross-coupling reactions
idine (67% of 6k, Table 2, entry 15) and disubstituted under aerobic conditions. This protocol is character-
iodoarenes such as 1-iodo-3,5-dimethylbenzene (61% ized by good yields even with very low catalyst load-
of 6l, Table 2, entry 16) turned out to be less efficient. ings down to the ppm scale. It is compatible with a
As observed for the Heck reaction its electron-poor broad selection of functional groups in the haloarene
fluoro analogue, 1-iodo-3,5-bis(trifluoromethyl)ben- varying in their electronic and steric properties. In
zene, was totally unreactive under our standard condi- comparison with bis-imidazolium and bis-benzimida-
tions, and the starting materials were completely re- zolium dibromide congeners the deprotonation of bis-
covered.
perimidinium dibromide generates an NHC ligand
The phenylation of iodotoluene was chosen as a with increased s-donor ability improving the efficien-
model reaction for a comparative study of the luti- cy of the palladium catalyst formed in situ in the
dine-bridged salts 1–3 as precatalysts for the Suzuki series of bis-imidazolium, bis-benzimidazolium and
reaction. The yields obtained for the resulting 4-phe- bis-perimidinium dibromide precatalysts. These re-
nyltoluene 6d increased from 49% to 70% and 93% sults render the perimidine skeleton a promising
in the series of bis-imidazolium (1), bis-benzimidazoli- target for further development and optimization of
um (2) and bis-perimidinium dibromide (3), respec- transition metal based catalysts.
tively (Table 2, entries 17, 18 and 8) confirming the
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A Lutidine-Bridged Bis-Perimidinium Salt: Synthesis and Application
COMMUNICATIONS
room temperature. The work-up of the reaction was per-
formed as described above for the Heck reaction.
Experimental Section
General Remarks
Supporting Information
Commercial reagents and solvents were used without fur-
ther purification. All reactions were carried under the air
Detailed synthetic procedures and spectroscopic data for the
bis-perimidinylidene palladium complex are given in the
Supporting Information.
unless otherwise noted. H and 13C NMR spectra were re-
1
corded on Bruker 400 DRX/300 DPX spectrometers. ESI
mass spectra were recorded on a Bruker Daltonics Announ-
ces Autoflex ESI mass spectrometer. GC-MS analyses were
obtained from a HP 5890 Series II. Lutidine-bridged bis-imi-
dazolium dibromide 1 and its bis-benzimidazolium analogue
2 (R=n-Bu and X=Br) were synthesized according to liter-
ature procedures.[6d,16]
Acknowledgements
We thank the referees for suggesting the mercury test. T.T.
thanks the Alexander-von-Humboldt-Foundation for a re-
search fellowship. J. M. thanks the Konrad-Adenauer-Foun-
dation for a PhD grant. Financial support from the DFG
(SFB 624 “Templates”) is gratefully acknowledged.
Synthesis of Lutidine-Bridged Bis-perimidinium
Dibromide 3
A mixture of 2,6-dibromolutidine (265 mg, 1 mmol) and N-
butylperimidine[10] (500 mg, 2.2 mmol) was heated to 1658C
under stirring in a sealed tube for 24 h. Then the mixture
was cooled to room temperature, the residue was dissolved
in CHCl3 and reprecipitated upon addition of cold Et2O to
give NMR-pure bis-perimidinium dibromide 3 as a bright
yellow powder in almost quantitative yield. 1H NMR
(DMSO-d6, 400 MHz, 298 K): d=8.44 (s, 2H), 7.21 (t, J=
7.8 Hz, 1H), 6.91 (d, J=7.8 Hz, 2H), 6.62–6.69 (m, 4H),
6.47 (d, J=8.3 Hz, 2H), 6.13–6.18 (m, 4H), 5.72 (d, J=
7.5 Hz, 2H), 4.52 (s, 4H), 2.97 (t, J=7.5 Hz, 4H), 0.83–0.92
(m, 4H), 0.61 (sextet, J=7.5 Hz, 4H), 0.12 (t, J=7.3 Hz,
6H); 13C NMR (DMSO-d6, 75 MHz): d=153.63, 152.18,
138.73, 134.05, 133.40, 132.23, 131.87, 130.87, 129.54, 128.31,
127.52, 124.03, 123.36, 122.49, 120.58, 108.15, 108.06, 54.70,
50.95, 27.91, 19.00, 13.55; MS (ESI): m/z=634.3 [MÀBr]+,
588.3, 329.2, 276.7 [MÀ2Br]2+, 224.1; HR-MS (ESI): m/z=
632.2383, calcd. for [MÀBr]+: 632.2383; anal. calcd. for
C37H39Br2N5·2H2O: C 59.29, H 5.78, N 9.34; found: C 59.04,
H 5.71, N 9.25.
References
[1] a) J. Dupont, C. S. Consorti, J. Spencer, Chem. Rev.
2005, 105, 2527; b) M. E. van der Boom, D. Milstein,
Chem. Rev. 2003, 103, 1759; c) M. Albrecht, G. van Ko-
ten, Angew. Chem. 2001, 113, 3866; Angew. Chem. Int.
Ed. 2001, 40, 3750.
[2] a) F. E. Hahn, M. C. Jahnke, Angew. Chem. 2008, 120,
3166; Angew. Chem. Int. Ed. 2008, 47, 3122; b) Recent
developments in the organometallic chemistry of N-het-
erocyclic carbenes, (Ed.: R. H. Crabtree), Coord.
Chem. Rev. 2007, 251, 595–896; c) N-Heterocyclic Car-
benes in Transition Metal Catalysis, (Ed.: F. Glorius),
Top. Organomet. Chem. 2007, 21, 1–218; d) O. Kuehl,
Chem. Soc. Rev. 2007, 36, 592; e) A. J. Boydston, C. W.
Bielawski, Dalton Trans. 2006, 4073; f) F. E. Hahn,
Angew. Chem. 2006, 118, 1374; Angew Chem. Int. Ed.
2006, 45, 1348; g) S. P. Nolan, N-Heterocyclic Carbenes
in Synthesis, Wiley-VCH, Weinheim, 2006.
[3] a) N. Marion, S. P. Nolan, Acc. Chem. Res. 2008, 41,
1440; b) N. Marion, S. P. Nolan, Chem. Soc. Rev. 2008,
37, 1776; c) S. Wuertz, F. Glorius, Acc. Chem. Res.
2008, 41, 1523; d) N. Marion, S. Diez-Gonzalez, S. P.
Nolan, Angew. Chem. 2007, 119, 3046; Angew. Chem.
Int. Ed. 2007, 46, 2988.
General Procedure for the Heck Reactions
To a suspension of K2CO3 (414 mg, 3 mmol.) in 10 mL NMP,
haloarene (2 mmol), n-butyl acrylate (307 mg, 2.4 mmol)
and the catalyst [prepared from equimolar amounts of Pd-
ACHTUNGTRENNUNG(OAc)2 and bis-perimidinium bromide 3 in NMP] were
added. The reaction mixture was heated at 1408C (moni-
tored by GC-MS) and then allowed to cool to room temper-
ature after the reaction was finished. Then the reaction mix-
ture was diluted with water, and the product was extracted
with ether (3ꢂ20 mL). The combined extracts were dried
over MgSO4, the organic phase was concentrated under
vacuum and the crude product was purified by flash column
chromatography (hexane/EtOAc=100/1).
[4] a) P. Bazinet, T.-G. Ong, J. S. OꢃBrien, N. Lavoie, E.
Bell, G. P. A. Yap, I. Korobkov, D. S. Richeson, Orga-
´ ´
nometallics 2007, 26, 2885; b) ꢄ. Alycy, N. Gꢅrbꢅz, B.
˙
C¸ etinkaya, Russ. J. Coord. Chem. 2005. 31, 142; c) I.
ꢄzdemir, B. Alici, N. Gꢅrbꢅz, E. C¸ etinkaya, B. C¸ etin-
kaya, J. Mol. Catal. A: Chem. 2004, 217, 37; d) P. Bazi-
net, G. P. A. Yap, D. S. Richeson, J. Am. Chem. Soc.
2003, 125, 13314.
[5] a) D. Benito-Garagorri, K. Kirchner, Acc. Chem. Res.
2008, 41, 201; b) D. Pugh, A. A. Danopoulos, Coord.
Chem. Rev. 2007, 251, 610; c) E. Peris, R. H. Crabtree,
Coord. Chem. Rev. 2007, 248, 2239; d) P. A. Chase, M.
Lutz, A. L. Spek, G. P. M. van Klink, G. van Koten, J.
Mol. Catal. A: Chem. 2006, 254, 2.
[6] a) A. V. Zabula, T. Pape, A. Hepp, F. M. Schappacher,
U. C. Rodewald, R. Poettgen, E. F. Hahn, J. Am.
Chem. Soc. 2008, 130, 5648; b) F. E. Hahn, M. C.
General Procedure for the Suzuki Reactions
To a suspension of K2CO3 (331 mg, 2.4 mmol.) in 3 mL
NMP, haloarene (2 mmol), phenylboronic acid (258 mg,
2.2 mmol) and catalyst [prepared from equimolar amounts
of Pd
N
added. The reaction mixture was heated at 1408C (moni-
tored by GC-MS and TLC) and then allowed to cool to
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Tao Tu et al.
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Jahnke, T. Pape, Organometallics 2007, 26, 150; c) F. E.
Hahn, M. C. Jahnke, T. Pape, Organometallics 2006, 25,
5927; d) F. E. Hahn, M. C. Jahnke, V. Gomez-Benitez,
D. Morales-Morales, T. Pape, Organometallics 2005, 24,
6458.
b) G. Bꢅhler, M. C. Feiters, R. J. M. Nolte, K. H. Dçtz,
Angew. Chem. 2003, 115, 2599; Angew. Chem. Int. Ed.
2003, 42, 2494.
[12] a) N. T. S. Phan, M. Van Der Sluys, C. W. Jones, Adv.
Synth. Catal. 2006, 348, 609; b) K. Q. Yu, W. Sommer,
J. M. Richardson, M. Weck, C. W. Jones, Adv. Synth.
Catal. 2005, 347, 161; c) K. Q. Yu, W. Sommer, M.
Weck, C. W. Jones, J. Catal. 2004, 226, 101; d) W. J.
Sommer, K. Q. Yu, J. S. Sears, Y. Y. Ji, X. L. Zheng,
R. J. Davis, C. D. Sherrill, C. W. Jones, M. Weck, Orga-
nometallics 2005, 24, 4351.
[7] a) T. Tu, X. Bao, W. Assenmacher, H. Peterlik, J. Da-
ACHTUNGTRENNUNGniels, K. H. Dçtz, Chem. Eur. J. 2009, 15, 1853; b) T.
Tu, W. Assenmacher, H. Peterlik, R. Weisbarth, M.
Nieger, K. H. Dçtz, Angew. Chem. 2007, 119, 6486;
Angew. Chem. Int. Ed. 2007, 46, 6368.
[8] T. Tu, J. Malineni, K. H. Dçtz, Adv. Synth. Catal. 2008,
350, 1791.
[13] D. E. Bergbreiter, P. L. Osbum, J. D. Frels, Adv. Synth.
[9] T. Tu, W. Assenmacher, H. Peterlik, G. Schnakenburg,
K. H. Dçtz, Angew. Chem. 2008, 120, 7236; Angew.
Chem. Int. Ed. 2008, 47, 7127.
[10] a) B. Alici, I. ꢄzdemir, K. Karaaslan, E. C¸ etinkaya, B.
C¸ etinkaya, J. Mol. Catal. A: Chem. 2005, 231, 261; b) B.
Alici, T. Hçkelek, E. C¸ etinkaya, B. C¸ etinkaya, Hetero-
at. Chem. 2003, 14, 82.
[11] a) T. Klawonn, A. Gansꢆuer, I. Winkler, T. Lauterbach,
D. Franke, R. J. M. Nolte, M. C. Feiters, H. Bçrner, J.
Hentschel, K. H. Dçtz, Chem. Commun. 2007, 1894;
Catal. 2005, 347, 172.
[14] a) D. Olsson, P. Nilsson, M. El Masnaouy, O. F. Wendt,
Dalton Trans. 2005, 1924; b) P. Nilsson, O. F. Wendt, J.
Organomet. Chem. 2005, 690, 4197; c) M. R. Eberhard,
Org. Lett. 2004, 6, 2125.
[15] a) E. Peris, R. H. Crabtree, Coord. Chem. Rev. 2004,
248, 2239; b) E. Peris, J. A. Loch, J. Mata, R. H. Crab-
tree, Chem. Commun. 2001, 201.
[16] R. S. Simons, P. Custer, C. A. Tessier, W. J. Youngs, Or-
ganometallics 2003, 22, 1979.
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asc.wiley-vch.de
ꢁ 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Adv. Synth. Catal. 2009, 351, 1029 – 1034