March 2005
In situ Preparation of Palladium
305
In conclusion, five 1,3-dialkylbenzimidazolium salts
1a-e) have been prepared and characterized. We have
demonstrated that simple method for Suzuki cross-cou-
pling reaction is presented which employs a catalyst
Compound 1c was prepared in the same way as 1a from 1-(2-
methoxyethylbenzimidazole (1.78 g, 11.12 mmol) and isopropyl
chloride (1.02 mL, 11.16 mmol) to give white crystals of 1c, 2.12
(
-1 1
g (75), mp 96-98 °C; IR, ν(CN): 1562 cm ; H NMR (CDCl ): δ
3
1
.85 (d, J6.6, 6H, CH(CH ) ); 3.19 (s, 3H, CH ); 3.82 (t, J3.2,
3 2 3
formed in situ from Pd(OAc) , the readily accessibly and
2
2H, CH CH ); 4.79 (t, J3.2, 2H, CH CH ); 5.09 (sept, J6.6, 6H,
2 2 2 2
fully air stable benzimidazolium salts. The new ligand
family allows highly efficient coupling reactions of elec-
tron rich as well as electron poor aryl chlorides with
phenylboronic acid under mild conditions.
Detailed investigations, focusing on imidazolin-2-yli-
dene and benzimidazolin-2-ylidene substituent effects,
functional group tolerance and catalytic activity in this and
other coupling reactions are ongoing.
13
CH(CH ) ); 7.49-7.74 (m, 4H, Ar-H); 10.11 (s, 1H, 2-CH).
C
3
2
NMR (CDCl ): δ 18.2 (CH(CH ) ); 30.5 (CH(CH ) ); 47.9
3
3 2
3 2
(CH ); 59.3, 70.5 (CH CH ); 113.9, 114.0, 127.1, 129.7, 131.8
3
2
2
(Ar-C); 142.8 (2-CH).
Anal. Calcd. For C H N OCl: C, 61.29, H, 7.46, N, 11.00.
13 19 2
Found C, 61.42, H, 7.49, N, 11.04.
Synthesis of 1-(2-Phenylethyl)-3-(2-methoxyethyl)benzimida-
zolium Bromide (1d).
Compound 1d was prepared in the same way as 1a from 1-(2
methoxyethyl)benzimidazole (0.8 g, 4.54 mmol) and 2-phenyl-
ethyl bromide (0.62 mL, 4.58 mmol) ) to give white crystals of
EXPERIMENTAL
-1 1
1
d, 1.12 g (86 %), mp 90-92 °C; IR, ν(CN): 1564 cm ; H NMR
All reactions were carried out under argon and standard high
vacuum-line techniques. Solvents were analytical grade and dis-
(
CDCl ): δ 3.21 (s, 3H, CH ); 3.82 (m, 2H, PhCH CH ); 4.00 (t,
3
3
2
2
J3.2, 2H, CH CH O); 4.72 (m, 4H, CH CH O, CH CH Ph);
2
2
2
2
2
2
tilled under nitrogen from sodium benzophenone (Et O, diox-
2
13
6
.73-7.64 (m, 9H, Ar-H); 9.34 (s, 1H, 2-CH); C NMR (CDCl3):
1
13
ane). H NMR and C NMR spectra were recorded using a
δ 48.3 (CH ); 36.1, 49.5, 59.3, 70.5 (CH CH ); 114.1, 114.1,
3
2
2
1
Bruker AC300P FT spectrometer operating at 300.13 MHz ( H),
5.47 MHz ( C). Chemical shifts (δ) are given in ppm relative
to TMS, coupling constants (J) in Hz. FT-IR spectra were
recorded on a Mattson 1000 spectrophotometer, wave numbers in
cm . Elemental analyses were performed by TUBITAK
Ankara, Turkey) Microlab.
1
27, 129.6, 129.7, 131.2, 32.1, 135, 135.4 (Ar-C); 143.6 (2-CH).
Anal. Calcd. For C H N OBr: C, 59.83, H, 5.81, N, 7.75.
13
7
1
8 21 2
Found C, 60.04, H, 5.84, N, 7.78.
-
1
Synthesis of 1,3-Di(2-phenylethyl)benzimidazolium Bromide
(1e).
(
Compound 1e was prepared in the same way as 1a from 1-(2-
Synthesis of 1,3-Di(2-methoxyethyl)benzimidazolium Chloride
1a).
phenylethyl)benzimidazole (3.3 g, 15.00 mmol) and 2-
phenylethyl bromide (2.03 mL, 15.00 mmol) to give white crys-
(
To a solution of 1-(2-methoxyethyl)benzimidazole (2 g, 11.36
mmol) in DMF (1 mL) 2-methoxyethyl chloride (1.03 mL, 11.42
mmol) was added and the resulting solution was stirred for 1 h at
-1 1
tals of 1e, 5 g (82 %), mp 164-166 °C; IR, ν(CN): 1565 cm ; H
NMR (CDCl ): δ 2.74 (t, J 7.1, 4H, PhCH CH ); 4.23 (t, J 7.1,
3
2
2
4
H, PhCH CH ); 6.58-7.43 (m, 9H, Ar-H); 9.89 (s, 1H, 2-CH);
2
2
room temperature and heated for 5 h at 80 °C. Then, Et O (10
13
2
C NMR (CDCl ): δ 35.2, 49.1 (PhCH CH ); 113.4, 127.4,
3 2 2
mL) was added the reaction mixture. A white solid precipitated in
this period. The precipitate was then crystallised from
1
29.2, 129.3, 131.2, 136.4 (Ar-C); 143.0 (2-CH).
Anal. Calcd. For C H N Br; C, 67.81, H, 5.65, N, 6.88.
2
3 23 2
EtOH/Et O (1:2). 2.80 g (91 %), mp 134-135°C; IR, ν(CN): 1564
2
Found C,68.05, H, 5.63, N, 6.90.
-1 1
cm ; H NMR (CDCl ): δ 3.27 (s, 6H, CH ); 3.87 (t, J1.2, 4H,
3
3
General Procedure for the Suzuki Type Coupling Reactions.
CH CH ); 4.80 (t, J1.2, 4H, CH CH ); 7.53-7.84 (m, 4H, Ar-H);
2
2
2
2
1
3
1
1.01 (s, 1H, 2-CH); C NMR (CDCl ): δ 48.0 (CH ); 59.3, 70.5
Pd(OAc) (1.5 %mmol), 1,3-dialkylbenzimidazolium salt, 1a-
3
3
2
(
CH CH ); 114.0, 114.1, 127.2, 132.1 (Ar-C); 143.60 (2-CH).
e, (3 % mmol), aryl chloride (1.0 mmol), phenylboronic acid (1.2
mmol), t-BuOK (2 mmol) dioxane (3 mL) were added in a small
Schlenk tube under argon and the mixture was heated at 60 °C for
2
2
Anal. Calcd. For C H N O Cl: C, 57.67, H, 7.02, N, 10.35.
1
3 19 2 2
Found C, 57.52, H, 7.00, N, 10.31.
2
h. At the conclusion of the reaction, the mixture was cooled,
Synthesis of 1-(2-Methoxyethyl)-3-diphenylmethylbenzimida-
zolium Chloride (1b).
diluted with Et O, filtered through a pad of silicagel with copious
2
washings, concentrated and purified by flash chromatography on
silicagel. Purity of compounds is checked by NMR and yields are
based on arylchloride.
Compound 1b was prepared in the same way as 1a from 1-(2-
methoxyethyl)benzimidazole (2 g, 11.36 mmol) and diphenyl-
methyl chloride (2.03 mL, 11.39 mmol) to give white crystals of
Acknowledgements.
-1 1
1
b, 3 g (70 %), mp 254-255 °C; IR, ν(CN): 1550 cm ; H NMR
(
(
CDCl ): δ 3.19 (s, 3H, CH ); 3.80 (t, J4.2, 2H, CH CH ); 4.89
We thank to Technological and Scientific Research Council of
Turkey TÜBITAK [TÜBITAK TBAG-2474 (104T085) and
TÜBITAK COST D17] and the Inönü University Research Fund
for financial support of this work.
3
3
2
2
t, 2H, CH CH ); 7.12-7.49 (m, 14H, Ar-H); 10.59 (s, 1H, 2-
2
2
13
CH); C NMR (CDCl ): δ 48.3 (CH ); 59.2, 70.5 (CH CH );
1
3
3
2
2
14.7, 114.9, 127.3, 127.4, 128.7, 129.6, 129. 129.7, 131.2 (Ar-
C); 132.8, 135.7, (CH(C H ) ); 135.8 (2-CH).
6
5 2
Anal. Calcd. For C H N Ocl: C, 72.91, H, 6.07, N, 7.39.
Found C, 72.68, H, 6.08, N, 7.42.
2
3 23 2
REFERENCES AND NOTES
Synthesis of 1-(2-Methoxyethyl)-3-isopropylbenzimidazolium
*
Correspondence to: Ismail Özdemir, Inönü University,
Chloride (1c).
Faculty Science and Arts, Chemistry Deparment, 44069 Malatya,