Synthesis of 1,3-dialkylperhydrobenzimidazolinium salts and their catalytic properties in heck reactions

Article abstract of DOI:10.3987/COM-13-12678

Novel eight 1,3-dialkylperhydrobenzimidazolinium chloride salts 3a-h were prepared as precursors of N-heterocyclic carbenes by reacting N,N'-dialkylcyclohexanediamine, triethyl orthoformate and ammonium chloride. The salts were characterized spectroscopic

Full text of DOI:10.3987/COM-13-12678

HETEROCYCLES, Vol. 87, No. 4, 2013
897
HETEROCYCLES, Vol. 87, No. 4, 2013, pp. 897 - 908. © 2013 The Japan Institute of Heterocyclic Chemistry
Received, 6th February, 2013, Accepted, 27th February, 2013, Published online, 13th March, 2013
DOI: 10.3987/COM-13-12678
SYNTHESIS OF 1,3-DIALKYLPERHYDROBENZIMIDAZOLINIUM
SALTS AND THEIR CATALYTIC PROPERTIES IN HECK REACTIONS
Murat Yiğit,a,* Gülin Bayam,a Beyhan Yiğit,a and İsmail Özdemirb
a Department of Chemistry, Faculty of Science and Art, Adıyaman University,
02040 Adıyaman, Turkey
b Department of Chemistry, Faculty of Science and Art, Inönü University, 44260
Malatya, Turkey
Corresponding author; e-mail: myigit@adiyaman.edu.tr
Abstract - Novel eight 1,3-dialkylperhydrobenzimidazolinium chloride salts 3a-h
were prepared as precursors of N-heterocyclic carbenes by reacting
N,N’-dialkylcyclohexanediamine, triethyl orthoformate and ammonium chloride.
The salts were characterized spectroscopically and the complexes formed in situ
from Pd(OAc)2 and 3 have been tested as catalysts in homogenous Heck coupling
reactions.
The Palladium-catalyzed Mizoroki-Heck cross-coupling reaction of an olefin with aryl halides under
basic conditions is one of the highly efficient tools for the carbon–carbon bond formation in organic
synthesis.1-3 Phosphines generally have been used as ligands for the palladium-catalyzed Heck and Suzuki
coupling reactions. However, the phosphine ligands are expensive, toxic and sensitive to air and the
moisture.4-7 The strong electron donating property of N-heterocyclic carbene ligands leads to metal
complexes with high stability against heat, air and moisture. These properties of N-heterocyclic carbene
ligands make them alternatives to tertiary phosphines used in different transition metal-catalyzed
reactions such as C-C and C-N arylation, olefin metathesis, hydrogenation, hydrosilylation and
CO-ethylene co-polymerization reactions.8-19 Apart from phosphine and N-heterocyclic carbene ligands,
Schiff bases, amines, oxazolines, pyridines, hydroxyquinolines, hydrazones, tetrazoles, N-phenylurea
have been used as ligands in Heck and Suzuki coupling reactions.20-27 Use of ligand free palladium salts
for Heck reactions has been reported.28 However, ligandless catalysts such as palladium acetate are not

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HETEROCYCLES, Vol. 87, No. 4, 2013
good catalysts for the Heck reactions of unactivated aryl chlorides. Recently, Gibson et al and Jones et al
showed that palladium complexes with chiral ligands are well suited as catalysts for the asymmetric Heck
reactions.29,30 Saturated imidazolinium salts as precursors for N-heterocyclic carbenes are generally
prepared by alkylation of dihydroimidazole and by cyclization reactions of a secondary bisamine with
triethyl orthoformate in the presence of ammonium salt or N,N’-dialkyl-1,2-diaminoethane dihydro-
halides with triethyl orthoformate.31-33 The imidazolinium and benzimidazolium salts are an effective
ligand precursor for the coupling of unactivated, activated and deactivated chlorides. In situ prepared
catalysts from these salts and palladium acetate gave effective catalysts for Suzuki coupling of aryl
chlorides and Heck coupling of aryl bromides in aqueous DMF at 80 °C. Both class N-heterocyclic
carbene precursor appeared to give similar activities.34-37
We recently reported the synthesis of N-heterocyclic carbene derivative ligands and their palladium(II)
carbene complexes and investigated for catalytic activity in Heck and Suzuki reactions.38-43 In this
article we wish to report the synthesis of new 1,3-dialkylperhydrobenzimidazolinium chloride salts 3a-h
(scheme 1), and their application to Heck cross-coupling with aryl halides.
The synthesis of 1,3-dialkylperhydrobenzimidazolinium salts is shown in Scheme 1. The Schiff bases 1
were prepared by the condensation of 1,2-diaminocyclohexane with aromatic aldehydes in ethanol.
Reduction of these Schiff bases with sodium borohydride in methanol gave the
N,N’-dialkylcyclohexane-1,2-diamines 2. The symmetrical 1,3-dialkylperhydrobenzimidazolinium salts 3
were easily synthesized in high yields from the N,N’-dialkylcyclohexane-1,2-diamines, triethyl
ortoformate and ammonium chloride. After purification, the 1,3-dialkylperhydrobenzimidazolinium salts
3a-h were isolated as colorless solids except for 3h in good yields (78-89%). The salts are soluble in the
common polar solvents and are air- and moisture stable both in the solid state and in solution. The
structures of 1,3-dialkylperhydrobenzimidazolinium salts were determined by their spectroscopic data and
elemental analyses (see Experimental section). The 13C- NMR spectra of 3a-h show only sharp high field
signals [162.35 (3a), 162.57 (3b), 162.44 (3c), 162.02 (3d), 162.18 (3e), 162.28 (3f), 162.11 (3g), 161.55
ppm (3h)] for the imino carbon and for a benzylic carbon [67.40 (3a), 68.28 (3b), 67.82 (3c), 66.08 (3d),
66.75 (3e), 66.74 (3f), 66.70 (3g), 68.93 ppm (3h)]. The 1H-NMR spectra of the
perhydrobenzimidazolinium salts further supported the assigned structures. The resonances of the C(2)-H
were observed as sharp singlets at  = 10.56, 9.89, 10.37, 10.74, 10.82, 8.63, 10.81, 9.36 ppm for 3a-h,
respectively. While the benzylic protons for 3c appeared as a singlet at 4.90 ppm, others appeared as a
doublet in the range 4.62-5.84 ppm. The IR data for perhydrobenzimidazolinium 3a-h salts clearly
indicate the presence of the –C=N– group with a (C=N) vibration at 1512-1619 cm-1. These NMR and IR
values were similar to those reproted for other 1,3-dialkylperhydrobenzimidazolinium and
1,3-dialkylimidazolinium salts.38,44

HETEROCYCLES, Vol. 87, No. 4, 2013
899
Ar
Ar
Ar
N
+)
N
NH
NH
NH2
NH2
N CH Ar
N CH Ar
Ar-CHO
Cl-
+
Ar
3 a-h
1
2
N
N
N
N
+) Cl-
N
+) Cl-
N
+) Cl-
N
+) Cl-
N
3a
3b
3c
3d
OMe
OMe
OMe
OEt
MeO
OMe
OMe
N
N
N
N
+) Cl-
+) Cl-
N
+) Cl-
N
+) Cl-
N
N
OMe
OMe
OEt
MeO
OMe
OMe
OMe
3e
3f
3g
3h
Scheme 1. Synthesis of 1,3-dialkylperhydrobenzimidazolinium salts
Pd-Catalyzed Heck reaction between aryl halides and alkenes is very useful methods to prepare styrene
derivatives, which are important chemicals for many applications. A variety of parameters such as base,
solvent, time, temperature, ligands and nature of the catalyst can influence the reactivity of Heck coupling
reactions. The published results showed that N-heterocyclic carbenes were efficient ligands for the
Pd-catalyzed Heck coupling reactions. The choice of bases and solvents are usually important in
achieving an efficient cross coupling reaction. For optimal reaction conditions, the Pd(OAc)2-catalyzed

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HETEROCYCLES, Vol. 87, No. 4, 2013
cross coupling of bromobenzene with styrene was employed as the model reaction using ligand 3a at 80
C; Cs2CO3, K2CO3, K3PO4 and t-BuOK were tested as the base. We chose K2CO3 as a base and
DMF-water as a solvent that the most commonly used in the Heck reaction. Under these reaction
conditions, the coupling reactions of aryl bromides and styrene were carried out in DMF/H2O (3:3 mL)
with 1 mol% Pd(OAc)2, 2 mol% 3 and 2 equiv. K2CO3 for 2 h at 80 C. Reaction of
p-bromoacetophenone, p-bromotoluene, p-bromobenzaldehyde, p-bromoanisol and bromobenzene with
styrene gave a high yield using this catalytic system. Control experiments showed that palladium acetate
in the absence of 1,3-dialkylperhydrobenzimidazolinium salts was inactive under these conditions for
Heck reaction. However, the activated (electron-poor) and deactivated (electron-rich) aryl chlorides do
not react under these reaction conditions, and yields are typically <5%. The results are summarized in
Table 1.
Table 1. The Heck coupling reaction of aryl bromides with styrene
Pd(OAc)2 , salt
Br
R
+
R
DMF/H2O , K2CO3
Entry
1
Aryl bromide
Product
Catalyst Yielda,b,c (%)
3a
3b
3c
3d
3e
3f
93
95
98
97
98
99
98
97
80
84
86
85
87
88
86
85
2
3
O
4
O
C
Br
C
Me
Me
5
6
7
3g
3h
3a
3b
3c
3d
3e
3f
8
9
10
11
12
13
14
15
16
Br
Me
Me
3g
3h

HETEROCYCLES, Vol. 87, No. 4, 2013
901
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
3a
3b
3c
3d
3e
3f
92
94
97
95
96
98
93
95
81
88
89
85
87
89
84
86
94
92
96
95
94
97
93
95
Br
CHO
CHO
3g
3h
3a
3b
3c
3d
3e
3f
Br
OMe
OMe
3g
3h
3a
3b
3c
3d
3e
3f
Br
3g
3h
a Reaction conditions: 1.0 mmol of R-C6H4Br-p, 1.5 mmol of styrene, 2.0 mmol K2CO3, 1.0 mmol Pd(OAc)2, 2.0
b
c
mol% 3a-h. Purity of compounds is checked by NMR and isolated yields are based on aryl bromide. All
reactions were monitered by GC.
Of the five different aryl bromides, aryl bromides bearing electron-withdrawing groups react with styrene
affording the coupled products in excellent yields (Table 1, entries 6, 14, 22, 30 and 38). We observed
that the perhydrobenzimidazolinium salts bearing methyl groups (3b, 3c), tert-butyl group (3d) and
methoxy groups (3e, 3f, 3g) were the most effective of the salts than nonsubstituted counterparts (3a) for
the Heck reactions. It can be show these salts are an effective ligand precursor for the coupling of

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HETEROCYCLES, Vol. 87, No. 4, 2013
unactivated, activated and deactivated aryl bromides with styrene. These results are in agreement with
other reports.34,38
In summary, eight 1,3-dialkylperhydrobenzimidazolinium chloride salts 3a-h were prepared by reacting
N,N’-dialkylcyclohexanediamine, triethyl orthoformate and ammonium chloride, and their catalytic
activities in the Heck coupling reactions were investigated. This catalytic system provides good
conditions for the coupling of aryl bromides without additives such as tetrabutylammonium bromide in
air. All in situ prepared palladium complexes demonstrated good catalytic activity in Heck coupling
reactions. Particularly, the 3f catalyst system is seen to be the most effective in the Heck reactions of aryl
bromides with styrene.
EXPERIMENTAL
All reactions for the preparation of 1,3-dialkylperhydrobenzimidazolinium salts 3a-h were carried out
under argon using standard Schlenk-type flasks. Heck coupling reactions were carried out in air.
1,2-Diaminocyclohexane (mixture of cis and trans), aldehydes and other reagents were purchased from
1
13
Aldrich Chemical Co. (Turkey). All H- and C-NMR were recorded in CDCI3 using a Bruker AC300P
FT spectrometer operating at 300.13 MHz (1H) or 75.47 MHz (13C). Chemical shifts () are given in ppm
relative to TMS, coupling constants (J) in hertz. FT-IR spectra were recorded as KBr pellets in the range
400-4000 cm-1 on a Mattson 1000 spectrophotometer (wavenumbers, cm-1). GC were measured by
GC-FID on a Agilent 6890N gas chromatograph equipped with an HP-5 column of 30 m length, 0.32 mm
diameter and 0.25 m film thickness. Melting points were measured in open capillary tubes with an
Electrothermal-9200 melting point apparatus and uncorrected. Elemental analyses were performed at
Inönü University research center.
General synthesis of Schiff bases
A solution of the aldehydes (10 mmol) and 1,2-diaminocyclohexane (5 mmol) in EtOH (30 mL) was
heated under reflux 3 h, then volatiles were removed in vacuum to dryness. The crude product was
crystallized from toluene / hexane.
General synthesis of diamines
Sodium borohydride (15 mmol) was added portionwise over 30 min to a solution of diimine (10 mmol) in
MeOH (30 mL) at room temperature and reaction mixture was stirred for 12 h and then heated under
reflux for 1 h. Upon cooling to room temperature, the mixture was treated with 1 N HCl, and organic
phase was extracted with CH2Cl2 (3 x 30 mL). After drying over MgSO4 and evaporation, The crude
product was crystallized from toluene/hexane.

HETEROCYCLES, Vol. 87, No. 4, 2013
903
Synthesis of 1,3-dibenzylperhydrobenzimidazolinium chloride (3a).
Chiral form of 3a was reported by Smith et al.45 A mixture of N,N’-dibenzyl-1,2-cyclohexanediamine
(1.82 g, 6.2 mmol), NH4Cl (0.33 g, 6.2 mmol) and triethyl orthoformate (10 mL) was heated for 12 h at
110 C. Upon cooling to room temperature, colorless crystals of 3a were obtained. The crystals were
filtered, washed with diethyl ether (3 x 15 mL) and dried under vacuum. The crude product was
1
recrystallized from EtOH/Et2O. Yield: 1.70 g, 81%, mp 155 C. IR (cm-1) : 1606 (NCN), H NMR
(CDCl3) : 10.56 (s, 1H, C-2H); 1.05-1.27 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.69-1.95 (m, 4H,
NCHCH2CH2CH2CH2CHN); 3.19-3.21 (m, 2H, NCHCH2CH2CH2CH2CHN); 4.77 and 5.48 (d, 4H, J =
11.1 Hz, CH2C6H5); 7.25-7.36 (m, 10H, CH2C6H5). 13C-NMR (CDCl3) : 162.35 (C-2); 23.77
(NCHCH2CH2CH2CH2CHN); 27.74 (NCHCH2CH2CH2CH2CHN); 51.22 (NCHCH2CH2CH2CH2CHN);
67.40 (CH2C6H5); 128.71, 128.98, 129.38, 133.48 (CH2C6H5). Anal. Calcd for C21H25N2Cl: C, 74.00; H,
7.34; N, 8.22. Found: C, 74.12; H, 7.39; N, 8.27.
Synthesis of 1,3-bis(2-methylbenzyl)perhydrobenzimidazolinium chloride (3b).
This compound was prepared in same way as 3a from N,N’-bis(2-methylbenzyl)-1,2-cyclohexanediamine
(2.12 g, 6.54 mmol), NH4Cl (0.35 g, 6.54 mmol) and triethyl orthoformate (10 mL) to give colorless
crystals of 3b. Yield: 2.15 g, 89%, mp 128 C. IR(cm-1) : 1600 (NCN), 1H NMR (CDCl3)  : 9.89 (s, 1H,
C-2H); 1.11-1.33 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.68-1.93 (m, 4H, NCHCH2CH2CH2CH2CHN);
3.35-3.38 (m, 2H, NCHCH2CH2CH2CH2CHN); 2.30 (s, 6H, CH2C6H5CH3-2); 4.89 and 4.97 (d, 4H, J =
11.7 Hz, CH2C6H4CH3-2); 7.11-7.26 (m, 8H, CH2C6H4CH3-2). 13C-NMR (CDCl3) : 162.57 (C-2); 23.83
(NCHCH2CH2CH2CH2CHN); 27.95 (NCHCH2CH2CH2CH2CHN); 49.53 (NCHCH2CH2CH2CH2CHN);
19.67 (CH2C6H4CH3-2); 68.27 (CH2C6H4CH3-2), 126.73, 129.02, 129.38, 131.26, 131.49, 136.82
(CH2C6H4CH3-2). Anal. Calcd for C23H29N2Cl: C, 74.89; H, 7.86; N, 7.59. Found: C, 74.96; H, 7.81; N,
7.63.
Synthesis of 1,3-bis(2,4-dimethylbenzyl)perhydrobenzimidazolinium chloride (3c).
This
compound
was
prepared
in
same
way
as
3a
from
N,N’-bis(2,4-dimethylbenzyl)-1,2-cyclohexanediamine (1.84 g, 5.23 mmol), NH4Cl (0.28 g, 5.23 mmol)
and triethyl orthoformate (10 mL) to give colorless crystals of 3c. Yield: 1.78 g, 86%, mp 157 C. IR
(cm-1) : 1619 (NCN), 1H NMR (CDCl3) : 10.37 (s, 1H, C-2H); 1.19-1.34 (m, 4H,
NCHCH2CH2CH2CH2CHN); 1.73-2.02 (m, 4H, NCHCH2CH2CH2CH2CHN); 3.25-3.28 (m, 2H,
NCHCH2CH2CH2CH2CHN); 2.28 and 2.31 (s, 12H, CH2C6H3(CH3)2-2,4); 4.90 (s, 4H,
13
CH2C6H3(CH3)2-2,4); 6.99-7.28 (m, 6H, CH2C6H3(CH3)2-2,4). C-NMR (CDCl3) : 162.44 (C-2); 23.63

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HETEROCYCLES, Vol. 87, No. 4, 2013
(NCHCH2CH2CH2CH2CHN); 27.78 (NCHCH2CH2CH2CH2CHN); 49.14 (NCHCH2CH2CH2CH2CHN);
19.48 and 21.05 (CH2C6H3(CH3)2-2,4); 67.82 (CH2C6H3(CH3)2-2,4); 127.21, 127.89, 129.29, 131.92,
136.45, 139.79 (CH2C6H3(CH3)2-2,4). Anal. Calcd for C25H33N2Cl: C, 75.66; H, 8.32; N, 7.06. Found: C,
75.61; H, 8.37; N, 7.12.
Synthesis of 1,3-bis(4-tert-butylbenzyl)perhydrobenzimidazolinium chloride (3d).
This compound was prepared in same way as 3a from N,N’-bis(4-tert-butylbenzyl)-1,2-
cyclohexanediamine (2.36 g, 5.79 mmol), NH4Cl (0.31 g, 5.79 mmol) and triethyl orthoformate (10 mL)
1
to give colorless crystals of 3d. Yield: 2.12 g, 81%, mp 245 C. IR (cm-1) : 1512 (NCN), H-NMR
(CDCl3) : 10.74 (s, 1H, 2-CH); 1.18-1.23 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.78-2.10 (m, 4H,
NCHCH2CH2CH2CH2CHN); 3.15-3.21 (m, 2H, NCHCH2CH2CH2CH2CHN); 1.27 (s, 18H,
CH2C6H4C(CH3)3-p); 4.66 and 5.02 (d, 4H, J = 15.0 Hz, CH2C6H4C(CH3)3-p); 7.32 and 7.36 (m, 8H, J =
8.3 Hz, and J = 8.5 Hz, CH2C6H4C(CH3)3-p). 13C-NMR (CDCl3) : 162.02 (2-CH); 23.58
(NCHCH2CH2CH2CH2CHN); 27.37 (NCHCH2CH2CH2CH2CHN); 50.45 (NCHCH2CH2CH2CH2CHN);
31.22 (CH2C6H4C(CH3)3-p); 34.61 (CH2C6H4C(CH3)3-p); 66.83 (CH2C6H4C(CH3)3-p); 126.10, 128.23,
129.96, 151.87 (CH2C6H4C(OCH3)3-p). Anal. Calcd for C29H41N2Cl: C, 76.90; H, 9.06; N, 6.19. Found: C,
76.24; H, 9.27; N, 6.02.
Synthesis of 1,3-bis(3,4-dimethoxybenzyl)perhydrobenzimidazolinium chloride (3e).
This compound was prepared in same way as 3a from N,N’-bis(3,4-dimethoxybenzyl)-1,2-cyclohexane-
diamine (3.11 g, 7.48 mmol), NH4Cl (0.40 g, 7.48 mmol) and triethyl orthoformate (10 mL) to give
1
colorless crystals of 3e. Yield: 2.92 g, 85%, mp 103 C. IR (cm-1) : 1588 (NCN), H-NMR (CDCl3) :
10.82 (s, 1H, 2-CH); 1.17-1.23 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.74-2.12 (m, 4H,
NCHCH2CH2CH2CH2CHN); 3.09-3.17 (m, 2H, NCHCH2CH2CH2CH2CHN); 3.84 and 3.92 (s, 12H,
CH2C6H3(OCH3)2-2,4); 4.63 and 4.95 (d, 4H, J = 14.6 Hz, CH2C6H3(OCH3)2-2,4); 6.77-6.88 (m, 4H,
13
CH2C6H3(OCH3)2-2,4) and 7.17 (s, 2H, CH2C6H3(OCH3)2-2,4). C-NMR (CDCl3) : 162.18 (2-CH);
23.62
(NCHCH2CH2CH2CH2CHN);
27.51
(NCHCH2CH2CH2CH2CHN);
50.74
(NCHCH2CH2CH2CH2CHN); 55.87 and 56.62 (CH2C6H3(OCH3)2-2,4); 66.75 (CH2C6H3(OCH3)2-2,4);
111.05, 111.87, 121.08, 125.53, 149.40, 149.68 (CH2C6H3(OCH3)2-2,4). Anal. Calcd for C25H33N2O4Cl:
C, 65.14; H, 7.16; N, 6.08. Found: C, 65.26; H, 7.34; N, 6.28.
Synthesis of 1,3-bis(2,4,6-trimethoxybenzyl)perhydrobenzimidazolinium chloride (3f).
This compound was prepared in same way as 3a from N,N’-bis(2,4,6-trimethoxybenzyl)-1,2-

HETEROCYCLES, Vol. 87, No. 4, 2013
905
cyclohexanediamine (2.22 g, 4.67 mmol), NH4Cl (0.25 g, 4.67 mmol) and triethyl orthoformate (10 mL)
1
to give colorless crystals of 3f. Yield: 1.89 g, 78%, mp 214-216 C. IR (cm-1) : 1591 (NCN), H NMR
(CDCl3) : 8.63 (s, 1H, C-2H); 1.16-1.43 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.80-2.28 (m, 4H,
NCHCH2CH2CH2CH2CHN); 2.82-3.03 (m, 2H, NCHCH2CH2CH2CH2CHN); 3.78 and 3.79 (s, 18H,
CH2C6H2(OCH3)2-2,4,6); 4.42 and 4.45 (d, 4H, J = 14.4 Hz, CH2C6H2(OCH3)2-2,4,6); 6.08 (s, 4H,
13
CH2C6H2(OCH3)2-2,4,6). C-NMR (CDCl3) : 162.28 (C-2); 22.35 (NCHCH2CH2CH2CH2CHN); 27.33
(NCHCH2CH2CH2CH2CHN);
39.30
(NCHCH2CH2CH2CH2CHN);
55.90
and
55.95
(CH2C6H2(OCH3)2-2,4,6); 66.74 (CH2C6H2(OCH3)2-2,4,6); 90.58, 101.67, 159.61, 161.86
(CH2C6H2(OCH3)2-2,4,6). Anal. Calcd for C27H37N2O6Cl: C, 62.24; H, 7.10; N, 5.34. Found: C, 62.30; H,
7.19; N, 5.41.
Synthesis of 1,3-bis(4-ethoxy-3-methoxybenzyl)perhydrobenzimidazolinium chloride (3g).
This compound was prepared in same way as 3a from N,N’-bis(4-ethoxy-3-methoxybenzyl)-1,2-
cyclohexanediamine (2.49 g, 5.61 mmol), NH4Cl (0.30 g, 5.61 mmol) and triethyl orthoformate (10 mL)
1
to give colorless crystals of 3g. Yield: 2.25 g, 82%, mp 85-86 C. H-NMR (CDCl3) : 10.81 (s, 1H,
2-CH); 1.09-1.23 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.72-2.12 (m, 4H, NCHCH2CH2CH2CH2CHN);
3.08-3.20 (m, 2H, NCHCH2CH2CH2CH2CHN); 3.92 (s, 6H, CH2C6H3(OCH3)-3); 1.44 (t, 6H, J = 6.9 Hz
CH2C6H3(OCH2CH3)-p); 4.06 (q, 4H, J = 6.9 Hz, CH2C6H3(OCH2CH3)-p); 4.62 and 4.96 (d, 4H, J = 14.7
Hz, CH2C6H3(OCH3)-3); 6.77-6.86 and 7.12-7.15 (m, 6H, CH2C6H3(OCH3)-3). 13C-NMR (CDCl3) :
162.11 (2-CH); 23.62 (NCHCH2CH2CH2CH2CHN); 27.51 (NCHCH2CH2CH2CH2CHN); 50.76
(NCHCH2CH2CH2CH2CHN); 56.64 (CH2C6H3(OCH3)-3); 64.30 (CH2C6H3(OCH2CH3)-p); 14.73
(CH2C6H3(OCH2CH3)-p); 66.70 (CH2C6H3(OCH3)-3); 112.10, 112.37, 121.07, 125.36, 148.75, 149.91
(CH2C6H3(OCH3)-3). Anal. Calcd for C27H37N2O4Cl: C, 66.32; H, 7.57; N, 5.73. Found: C, 66.45; H,
7.68; N, 5.61.
Synthesis of 1,3-bis(9-anthracenylmethyl)perhydrobenzimidazolinium chloride (3h).
This compound was prepared in same way as 3a from N,N’-bis(9-anhtracenylmethyl)-1,2-
cyclohexanediamine (3.52 g, 7.10 mmol), NH4Cl (0.38 g, 7.10 mmol) and triethyl orthoformate (10 mL)
1
to give orange crystals of 3h. Yield: 3.22 g, 84%, mp 223-225 C. IR (cm-1) : 1612 (NCN), H NMR
(CDCl3) : 9.36 (s, 1H, C-2 H); 0.85-1.14 (m, 4H, NCHCH2CH2CH2CH2CHN); 1.44-1.71 (m, 4H,
NCHCH2CH2CH2CH2CHN); 3.41-3.43 (m, 2H, NCHCH2CH2CH2CH2CHN); 5.76 and 5.84 (d, 4H, J =
11.4 Hz, CH2An); 7.41 and 7.50 (t, 8H, J = 6.3 Hz, AnH) (An: anthracene); 7.89 and 8.21 (d, 8H, J = 6.0
Hz, J = 6.6 Hz, AnH); 8.37 (s, 2H, AnH). 13C-NMR (CDCl3) : 161.51 (C-2); 23.75

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(NCHCH2CH2CH2CH2CHN); 27.94 (NCHCH2CH2CH2CH2CHN); 44.16 (NCHCH2CH2CH2CH2CHN);
68.93 (CH2An); 122.72, 123.36, 123.76, 125.50, 125.90, 127.95, 129.32, 129.49, 129.56, 130.02, 130.90,
131.31, 132.35, 135.41 (AnC). Anal. Calcd for C37H33N2Cl: C, 82.14; H, 6.10; N, 5.18. Found: C, 82.21;
H, 6.19; N, 5.25.
General procedure for the Heck coupling reactions
Pd(OAc)2 (1.0 mmol%), the appropriate 1,3-dialkylperhydrobenzimidazolinium salt 3a-h (2 mmol%),
aryl bromide (1.0 mmol), styrene (1.5 mmol), K2CO3 (2 mmol), water (3 mL) and DMF (3 mL) were
◦
added to a small Schlenk tube and the mixture was heated at 80 C for 2 h. At the conclusion of the
reaction, the mixture was cooled, extracted with EtOAc–hexane (1 :5), filtered through a pad of silica gel
with copious washing, concentrated and purified by flash chromatography on silica gel. All reactions
were monitored by GC. The purity of the compounds was checked by NMR and yields are based on aryl
bromide.
ACKNOWLEDGEMENTS
We thank the Adıyaman University Research Fund (FEFBAP 2009-8, FEFYL 2010-0001) for financial
support of this work.
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