Imidazole, pyrimidine and diazepine containing heteroaryl-substituted heterocyclic salts as efficient ligand precursors for Mizoroki-Heck coupling reaction: Synthesis, structural characterization and catalytic activities

Article abstract of DOI:10.1007/s13738-014-0449-z

The nine new heteroaryl-substituted imidazolidinium (1a-c), pyrimidinium (2a-c) and diazepinium (3a-c) salts as N-heterocyclic carbene (NHC) precursors were synthesized in good yields and entirely characterized using elemental analyses and conventional sp

Full text of DOI:10.1007/s13738-014-0449-z

J IRAN CHEM SOC
DOI 10.1007/s13738-014-0449-z
ORIGINAL PAPER
Imidazole, pyrimidine and diazepine containing heteroaryl-
substituted heterocyclic salts as efficient ligand precursors
for Mizoroki–Heck coupling reaction: synthesis, structural
characterization and catalytic activities
Yetkin G o¨ k
Muhammad Nawaz Tahir
•
Senem Akkoc¸
•
Mehmet Akkurt
•
Received: 6 January 2014 / Accepted: 5 March 2014
Iranian Chemical Society 2014
ꢀ
Abstract The nine new heteroaryl-substituted imidazo-
lidinium (1a–c), pyrimidinium (2a–c) and diazepinium
Keywords Imidazolidinium salt ꢀ Pyrimidinium salt ꢀ
Diazepinium salt ꢀ Mizoroki–Heck coupling reaction ꢀ
Catalyst ꢀ X-ray diffraction
(
3a–c) salts as N-heterocyclic carbene (NHC) precursors
were synthesized in good yields and entirely characterized
using elemental analyses and conventional spectroscopic
methods. In situ formed complexes from heterocyclic salts
t
1–3), Pd(OAc) and in the presence of KOBu as a base
Introduction
(
2
were tested as catalysts for the Mizoroki–Heck coupling
reaction in an aqueous media and very high yields were
achieved. 1,3-Di(5-methylthiophen-2-ylmethyl)pyrimidini-
um hexafluorophosphate salt (2b) was structurally charac-
terized by single-crystal X-ray diffraction. In the 2b
Transition metal-catalyzed carbon–carbon coupling reac-
tions are very powerful tools in numerous organic trans-
formations. In modern organic synthesis, the Mizoroki–
Heck reaction, which consists of the coupling of an
alkene with a halo compound, has become a corner stone
[1]. This significance reaction has become a subject of
major interest at industrial level and its applications in the
laboratory [2, 3]. In recent years, sterically hampered
carbene ligands, NHCs and electron rich alkyl phosphines
have received increasing interest [4–10]. Diverse NHC
ligands have been prepared in short time and some of
them, for a variety of palladium-catalyzed transforma-
tions, have been used successfully [11–15]. However,
industrial applications of Mizoroki–Heck reactions are
rare, chiefly due to the following two problems [16, 17]:
Firstly, palladium is costly and pollution of the product by
palladium has to be firmly controlled. Secondly, many
phosphine ligands are even more expensive and they are
not appropriate to work with as they are subject to P–C
bond degradation at elevated temperature, are poisonous
and air sensitive [18].
?
-
compound (C H N S ) [PF ] , the terminal thiophene
1
6
21
2
2
6
rings are twisted with a dihedral angle of 72.8(3)ꢁ. In the
pyrimidine ring, the three successive C atoms between the
N atoms are disordered over two positions [occupancy ratio
0
.753(12):0.247(12)]. In the crystal, neighboring molecules
are linked by C–H…F hydrogen bonds, running along the
b axis.
Y. G o¨ k
Department of Chemistry, Faculty of Science, Erciyes
University, Kayseri, Turkey
e-mail: yetkin.gok@inonu.edu.tr
S. Akko c¸ (&)
Department of Chemistry, Faculty of Science and Arts, In o¨ n u¨
University, Malatya, Turkey
e-mail: senemakkoc@erciyes.edu.tr
Recently, the advantages brought to fine chemistry by
means of the easy substitution of a phosphine ligand by a
nucleophilic heterocyclic diaminocarbene, such as imi-
dazolidine and benzimidazolidine ligands, have brought
important advancements in catalytic activity. Illustrative
instances are found in Mizoroki–Heck coupling reactions
[19–21], cyclopropanation [22], hydrogenation [23, 24],
M. Akkurt
Department of Physics, Faculty of Science, Erciyes University,
Kayseri, Turkey
M. N. Tahir
Department of Physics, Sargodha University, Sargodha, Pakistan
123

J IRAN CHEM SOC
R
R
R
E
E
E
NH2
NH2
N
N
NH
NH
N
NaBH4
CH(OEt)
3
PF -
n(H C)
+ 2 HOC
R
(H
C)
(H C)
(H C)
2
2
n
2
n
2
n
6
E
CH OH
NH PF6
3
4
N
A
B
E
R
E
n=0, 1a-c
n=1, 2a-c
n=2, 3a-c
E
R
R
C
D
E
CH3
CH3
CH
3
CH3
O
PF6-
O
S
N
O
S
N
CH3
CH3
CH3
N
N
N
N
N
N
N
N
N
N
N
PF6-
S
-
PF -
-
PF
PF
PF -
6
6
6
6
N
N
O
CH
3
S
N
CH3
CH
3
CH3
CH3
1
a
1b
1c
2a
2b
2c
CH3
CH
3
O
S
N
CH3
CH3
N
N
N
N
PF6-
PF6-
PF -
6
N
N
O
S
N
CH3
CH3
3
a
3b
3
c
Scheme 1 Synthesis of heteroaryl-substituted imidazolidinium (1a–c), pyrimidinium (2a–c) and diazepinium (3a–c) salts
ruthenium catalysts for the formation of furans [25],
methathesis [26], hydrosilylation [27] and rhodium cata-
lysts for arylation [28]. A number of significant roles in
homogeneous catalysis, such as controlling activity and
providing a stabilizing effect as well as selectivity by
altering electronic and steric parameters, are provided by
the ancillary ligand coordinated to the metal center. In
tuning the catalytic activity, the position, number and
nature of the substituents on the N atom(s) and/or NHC
ring play a crucial role.
Results and discussion
Characterization of the heteroaryl-substituted
heterocyclic salts, 1–3
1,3-Dialkylimidazolidinium (1a–c), 1,3-dialkylpyrimidini-
um (2a–c) and 1,3-dialkyldiazepinium (3a–c) salts are
NHC precursors. The synthesis of salts containing furan,
thiophene and pyrrol moieties was achieved by the reaction
0
0
of N,N -dialkylethane-1,2-diamine, N,N -dialkylpropane-
0
Herein, to find efficient palladium catalysts we prepared
a series of new heterocyclic salts (1–3) containing furan,
thiophene and pyrrol moieties (Scheme 1). The crystal
structure of 1,3-di(5-methylthiophen-2-ylmethyl)imidazo-
lidinium hexafluorophosphate salt (1b) is reported here.
We also reported the use of in situ formed catalytic system
1,3-diamine and N,N -dialkylbutane-1,4-diamine with
ammonium hexafluorophosphate in triethyl orthoformate
for 1–3, respectively (Scheme 1). The resulting imidazo-
lidinium, pyrimidinium and diazepinium salts were
obtained in very good yields of 75–95 %. The structures of
1
salts 1–3 were determined by spectroscopic methods ( H
1
3
consisting of Pd(OAc) as palladium source, 1–3 as car-
2
t
bene precursors and KOBu as a base for the coupling of
NMR, C NMR and FT-IR) and elemental analyses. Also,
1,3-di(5-methylthiophen-2-ylmethyl)pyrimidinium hexa-
fluorophosphate salt (2b) was structurally characterized by
styrene with different aryl bromides in aqueous media.
New heteroaryl-substituted imidazolidin-2-ylidene, pyrim-
idin-2-ylidene and diazepin-2-ylidene palladium(II) sys-
tems exhibited quite high catalytic activity.
1
single-crystal X-ray diffraction method. The H NMR
spectra of the heterocyclic salts containing furan, thiophene
and pyrrol moieties further supported the assigned
1
23

J IRAN CHEM SOC
m(C=N) value because of the p-electron delocalization in
the heterocyclic ring.
Single crystal and molecular structure
A single crystal of the heteroaryl-substituted salt 2b, which
is suitable for X-ray diffraction, was obtained by slow
diffusion of dichloromethane into diethylether solutions at
ambient temperature. There is not appear lattice held
organic solvent molecules such as dichloromethane and
diethylether in the unit cells of the determined structure in
2b. The molecular view of compound 2b is represented in
Figs. 1 and 2.
The terminal thiophene rings (S1/C1–C4 and S2/C12–
C15) of the title compound make a dihedral angle of
Fig. 1 The molecular structure of the 2b compound with 30 %
probability displacement ellipsoids for non-H atoms. Only the major
disorder component is shown
72.8(3)ꢁ with each other. In the pyrimidine ring, the three
successive C7-C8-C9 atoms between the N1 and N2
atoms are disordered over two positions with the occu-
pancies of [0.753(12) and 0.247(12)]. The N1/N2/C7A-
C9A/C10 ring of the major component adopts an enve-
lope conformation [Puckering parameters [29] are
˚
Q = 0.415(11) A, h = 54.0(12)ꢁ and / = 118.8(16)ꢁ].
T
The other ring with the minor component is puckered
˚
with the puckering parameters of Q = 0.36(3) A,
T
h = 60(5)ꢁ and / = 227(5)ꢁ. All bond lengths and
angles are normal [30].
Mizoroki–Heck coupling reaction
It has been observed that the palladium-catalyzed coupling
of aryl bromides with styrene carries on under various
conditions. A wide range of bases (K CO , Cs CO and
2
3
2
3
t
KOBu ) and solvents (DMF, H O and dioxane), as well as
2
catalysts, in situ formed from Pd(OAc) and carbene pre-
2
cursors 1–3, has been employed with varying degrees of
success according to the substrates. A series of experiments
have been performed with styrene and 4-bromoacetophe-
Fig. 2 The crystal packing and hydrogen bonding of the 2b
compound along the b axis. H atoms not involved in hydrogen
bonding and the minor disordered component are omitted for clarity
none as model compounds to find optimum conditions. As
t
a base, KOBu was the best choice in DMF/H O systems.
2
In addition, the reactions were performed in air. After
determining the optimized coupling reaction conditions,
the efficiencies of the salts and reach of the reaction were
evaluated by investigating the coupling of various p-
substituted aryl bromides with styrene. The results are
given in Table 1.
structures; the resonances for C(2)-H were observed as
sharp singlets at 8.00, 8.67, 8.01, 7.96, 8.75, 8.51, 7.80,
7
.90 and 7.62 ppm, respectively, for the heterocyclic salts
1
–3. C NMR chemical shifts were consistent with the
3
1
proposed structure; the imino carbon atom appeared as a
1
typical singlet in the H-decoupled mode at 156.7, 157.4,
Quite active catalytic processes that are both stable
towards moisture and oxidant variations and easy to handle
are still being sought today. It is environmentally and
economically advantageous to use water as solvent for
chemical reactions, because it is nonflammable, economi-
cal, abundant, nonpoisonous and easily separable from
organic compounds [31]. Therefore, we used water toge-
ther with DMF as solvent in our study. Also, a number of
1
55.8, 154.0, 153.1, 152.4, 157.7, 157.1 and 156.6 ppm,
respectively, for 1–3. The NMR values are similar to those
found for 1,3-dialkylheterocyclic salts. The heterocyclic
salts (1–3) showed FT-IR absorption at 1,561.17, 1,525.26,
1
,504.49, 1,504.60, 1,561.53, 1,550.04, 1,563.31, 1,574.01
-
and 1,585.99 cm , respectively, which are assigned to
1
m(C=N). These values are slightly lower than the normal
123

J IRAN CHEM SOC
Table 1 The Mizoroki–Heck coupling reaction of styrene with various aryl bromides
t
KOBu , LHX, Pd(OAc)2
+
R
Br
80 C, 1 h
°
R
a, b, c
Entry
R
LHX
Yield (%)
1
2
3
4
5
6
7
8
9
COCH
COCH
COCH
COCH
COCH
COCH
COCH
COCH
COCH
CHO
3
3
3
3
3
3
3
3
3
1a
1b
1c
2a
2b
2c
3a
3b
3c
1a
1b
1c
2a
2b
2c
3a
3b
3c
1a
1b
1c
2a
2b
2c
3a
3b
3c
1a
1b
1c
2a
2b
2c
3a
3b
3c
1a
1b
1c
2a
2b
2c
3a
3b
96
89
89
76
81
81
95
78
95
99
99
96
99
95
98
99
94
98
64
73
89
87
84
98
92
84
99
97
95
79
61
97
94
97
98
99
94
75
87
95
93
92
92
92
1
1
1
1
1
1
1
1
1
1
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
4
4
4
4
4
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
CHO
CHO
CHO
CHO
CHO
CHO
CHO
CHO
OCH
OCH
OCH
OCH
OCH
OCH
OCH
OCH
OCH
3
3
3
3
3
3
3
3
3
CH
CH
CH
CH
CH
CH
CH
CH
CH
H
3
3
3
3
3
3
3
3
3
H
H
H
H
H
H
H
1
23

J IRAN CHEM SOC
Table 1 continued
a, b, c
Entry
R
H
LHX
Yield (%)
98
4
5
3c
a
t
Reaction conditions: aryl bromide (1.0 mmol), styrene (1.5 mmol), Pd(OAc)
3 mL)-DMF(3 mL), temperature 80 ꢁC, 1 h
2
2
(1.0 mmol %), KOBu (2.0 mmol), 1–3 (2.0 mmol %), H O
(
b
Purity of compounds is checked by GC and NMR spectroscopy
c
Yields are based on aryl bromide
reports show that water has been used as solvent in palla-
dium-mediated Mizoroki–Heck reactions [4, 5, 32, 33].
As the control experiment showed, the Mizoroki–Heck
coupling reaction in the absence of 1–3 did not occur.
Under the optimized reaction conditions, a diversity of aryl
bromides bearing electron-withdrawing or electron-donat-
ing groups reacted with styrene, affording the coupled
products in good to excellent yields. As expected, electron-
deficient bromides for the conversions proved to be bene-
ficial. According to these results, the in situ formed com-
plexes from imidazolidinium, pyrimidinium and
˚
Table 2 Hydrogen-bond parameters (A, ꢁ) for C16
H
21 2
N S
2
ꢀF
6
P (2b)
D–H
H…A
D…A
D–H…A
i
C8A–H8A2…F6
C10–H10…F4
0.97
0.93
2.41
2.36
3.264 (8)
3.224 (7)
146
155
ii
Symmetry codes: (i) 1 - x, 1 - y, 1 - z; (ii) 1 - x, -y, 1 - z
were measured in open capillary tubes with an Electro-
thermal 9200 melting point apparatus. Elemental analyses
were preformed by the TUBITAK Microlab.
diazepinium with Pd(OAc) were tested as catalysts for
2
Mizoroki–Heck coupling reactions in H O-DMF mixture.
2
General procedure for the preparation of the heteroaryl-
substituted heterocyclic salts, 1–3
The influence of the heteroaryl substituents on N atoms
was investigated under the same conditions in this coupling
reaction. All salts (1–3) exhibited very good catalytic
activities.
To a solution of diamine A (15 mmol) in toluene (20 mL),
heteroaryl-2-carbaldehyde B (29 mmol) was added slowly
at ice bath temperature and the resulting mixture was
stirred at 0 ꢁC for 18 h. Then, the solvent was removed in
vacuo. The formed Schiff bases C as crude products were
crystallized from diethylether/hexane (1:2) at room tem-
perature. To a solution of schiff bases C (24 mmol) in
In the crystal structure, C–H…F hydrogen bonds con-
nect the neighboring molecules along the b axis. In addi-
tion, p–p and C–H…p interactions are not observed. The
selected bond lengths and angles are given in Table 2.
H atoms bound to C atoms were positioned geometri-
cally and refined using a riding model, with C–
methyl alcohol (40 mL), NaBH (48 mmol) was added
4
˚
H = 0.93–0.97 A and U (H) = 1.2 or 1.5U (C). In the
iso
eq
slowly at room temperature and the resulting mixture was
stirred for 24 h. Then, the solvent was removed in vacuo,
and the obtained heteroaryl-substituted diamines D as
product were crystallized from a mixture of dichlor-
omethane/diethylether (1:1). Ammonium hexafluorophos-
phate (NH PF ) (1.0 mmol) was added to a solution of
pyrimidine ring, the three successive C atoms between the
N atoms are disordered over two sites, with approximate
occupancies of 0.753(12) and 0.247(12).
4
6
Experimental section
heteroaryl-substituted diamine D (1.0 mmol) in CH(OEt)3
5 mL) and the reaction mixture was heated for 12 h at
(
Materials and methods
80 ꢁC. A solid was precipitated. Then, the precipitated
heteroaryl-substituted heterocyclic salts E were crystal-
lized from ethyl alcohol/diethyl ether (1:2) at room
temperature.
All reactions for the preparation of heterocyclic salts (1–3)
containing furan, thiophene and pyrrol moieties were car-
ried out under argon in flame-dried glassware using stan-
dard Schlenk type flasks. Test reactions for the catalytic
activities of catalysts in the Mizoroki–Heck coupling
1,3-Di(5-methylfurfuryl)imidazolidinium
hexafluorophosphate, 1a
1
13
reaction were carried out in air. H and C NMR spectra
-
1
were recorded using a Bruker AC300P FT spectrometer
Yield: 76 %; m.p.: 30–31 ꢁC; IR: t(C=N): 1,561.17 cm
1
.
1
13
operating at 300.13 MHz ( H) and 75.47 MHz ( C).
Chemical shifts (d) were given in ppm relative to tetra-
methylsilane, coupling constant (J) in Hz. Melting points
H NMR (300.13 MHz, CDCl ), d 2.26 (s, 6 H, CH ); 3.89
3
3
(s, 4 H, NCH CH N); 4.57 (s, 4 H, NCH C H OCH );
3
2
2
2
4
2
5.89, 6.61 (d, 4 H, J 2.9 Hz, J 3.0 Hz, NCH C H OCH );
2
4
2
3
123

J IRAN CHEM SOC
1
3
8
.00 (s, 1 H, 2-CH). C NMR (75.47 MHz, CDCl ), d 13.5
NCH C H SCH ); 6.76–7.01 (m, 4 H, thiophene-H); 8.75
3
3
2
4
2
1
3
(
CH ); 44.7 (NCH CH N); 48.3 (NCH C H OCH ); 106.7,
2
(s, 1 H, 2-CH). C NMR (75.47 MHz, DMSO), d 15.5
(NCH CH CH N); 18.8 (CH ); 40.1 (NCH CH CH N);
3
2
2
2
4
3
1
12.4, 143.9 and 153.9 (NCH C H OCH ); 156.7 (2-CH).
2 4 2 3
2
2
2
3
2
2
2
Anal. Calcd. for C H N O PF : C, 44.56; H, 4.74; N,
6
52.9 (NCH -thiophene); 106.1, 129.3, 134.1 and 141.6
2
1
5
19
2
2
6
.93. Found: C, 44.48; H, 4.79; N, 6.95 %.
(thiophene-C); 153.1 (2-CH). Anal. Calcd. for C H N
6 21 2-
1
S PF : C, 42.66; H, 4.70; N, 6.22. Found: C, 42.77; H,
2 6
1
,3-Di(5-methylthiophen-2-ylmethyl)imidazolidinium
4.60; N, 6.26 %.
hexafluorophosphate, 1b
1
,3-Di(N-methylpyrrol-2-ylmethyl)pyrimidinium
Yield: 83 %; m.p.: 159–160 ꢁC; IR: t(C=N):
-
1 1
hexafluorophosphate, 2c
1
,525.26 cm . H NMR (300.13 MHz, DMSO), d 2.44 (s,
H, CH ); 3.78 (s, 4 H, NCH CH N); 4.79 (s,4 H,
6
3
2
2
Yield: 86 %; m.p.: 120–121 ꢁC; IR: t(C=N):
NCH C H SCH ); 6.75–6.99 (m, 4 H, thiophene-H); 8.67
2
4
2
3
-
1 1
1
3
1
,550.04 cm . H NMR (300.13 MHz, CDCl ), d 1.91 (p,
(
s, 1 H, 2-CH). C NMR (75.47 MHz, DMSO), d 15.5
CH ); 45.9 (NCH CH N); 48.0 (NCH C H SCH ); 126.1,
3
2
H, J 5.1 Hz, NCH CH CH N); 3.56 (s, 6 H, CH ); 3.21
2
(
2
2
3
3
2
2
2
4
2
3
(t, 4 H, J 6.0 Hz, NCH CH CH N); 4.66 (s, 4 H, CH C
2 2 2 2 4-
1
29.5, 133.4 and 141.6 (thiophene-C); 157.4 (2-CH). Anal.
H NCH ); 5.98–6.82 (m, 6 H, pyrrol-H); 8.51 (s, 1 H,
3
Calcd. for C H N S PF : C, 41.28; H, 4.39; N, 6.42.
6
3
1
1
5
19
2
2
3
2
-CH). C NMR (75.47 MHz, CDCl ), d 18.6 (NCH
Found: C, 41.36; H, 4.28; N, 6.39 %.
3
2-
CH CH N); 33.9 (CH ); 42.3 (NCH CH CH N); 49.9
2
2
3
2
2
2
(
CH C H NCH ); 107.2, 111.4, 124.2 and 124.9 (pyrrol-
2 4 3 3
1
,3-Di(N-methylpyrrol-2-ylmethyl)imidazolidinium
C); 152.4 (2-CH). Anal. Calcd. for C H N PF : C, 46.16;
16 23
hexafluorophosphate, 1c
4
6
H, 5.57; N, 13.46. Found: C, 46.25; H, 5.49; N, 13.47 %.
Yield: 80 %; m.p.: 103–104 ꢁC; IR: t(C=N):
-
1 1
1
,547.70 cm . H NMR (300.13 MHz, CDCl ), d 3.62 (s,
3
1
,3-Di(5-methylfurfuryl)diazepinium
6
H, CH ); 3.80 (s, 4 H, NCH CH N); 4.66 (s, 4 H, CH
2-
3
2
2
hexafluorophosphate, 3a
C H NCH ); 6.07–6.68 (m, 6 H, pyrrol-H); 8.01 (s, 1 H,
4
3
3
1
3
2
-CH). C NMR (75.47 MHz, CDCl ), d 33.7 (CH ); 43.7
3
3
Yield: 79 %; m.p.: 110–111 ꢁC; IR: t(C=N):
(
NCH CH N); 47.7 (NCH C H NCH ); 107.6, 111.8,
3
-1 1
2
2
2
4
3
1
4
3
,562.31 cm . H NMR (300.13 MHz, CDCl ), d 1.96 (p,
3
1
22.2 and 124.9 (pyrrol-C); 155.8 (2-CH). Anal. Calcd. for
H, J 2.8 Hz, NCH CH CH CH N); 2.29 (s, 6 H, CH );
3
2
2
2
2
C H N PF : C, 44.78; H, 5.26; N, 13.93. Found: C,
1
5
21
4
6
.71 (t, 4 H, J 5.7 Hz, NCH CH CH CH N); 4.56 (s, 4 H,
2
2
2
2
4
4.66; H, 5.35; N, 13.91 %.
NCH Furan); 5.97 and 6.42 (d, 4 H, J 2.2 Hz and J 3.1 Hz,
2
1
furan-H); 7.80 (s, 1 H, 2-CH). C NMR (75.47 MHz,
3
1
,3-Di(5-methylfurfuryl)pyrimidinium
CDCl ), d 13.6 (NCH CH CH CH N); 24.3 (CH ); 49.5
3
2
2
2
2
3
hexafluorophosphate, 2a
(NCH CH CH CH N); 54.0 (NCH Furan); 106.9, 112.6,
2 2 2 2 2
1
44.7 and 153.9 (furan-C); 157.7 (2-CH). Anal. Calcd. for
Yield: 85 %; m.p.: 170–171 ꢁC; IR: t(C=N):
C H N O PF : C, 47.23; H, 5.36; N, 6.48. Found: C,
6
-
1 1
17 23
2
2
1
,561.53 cm . H NMR (300.13 MHz, CDCl ), d 2.09 (p,
3
47.31; H, 5.33; N, 6.48 %.
2
H, J 5.9 Hz, NCH CH CH N); 2.29 (s, 6 H, CH ); 3.39
2
2
2
3
(
t, 4 H, J 5.9 Hz, NCH CH CH N); 4.57 (s, 4 H, NCH -
2 2 2 2
furan); 5.96–6.42 (m, 4 H, furan-H); 7.96 (s, 1 H, 2-CH).
3
1,3-Di(5-methylthiophen-2-ylmethyl)diazepinium
hexafluorophosphate, 3b
1
C NMR (75.47 MHz, CDCl ), d 13.4 (NCH CH CH N);
3
2
2
2
1
1
8.6 (CH ); 42.5 (NCH CH CH N); 51.5 (NCH -furan);
3 2 2 2 2
06.9, 112.8, 144.1 and 152.5 (furan-C); 154.0 (2-CH).
Yield: 75 %; m.p.: 132–133 ꢁC; IR: t(C=N):
-
1 1
Anal. Calcd. for C H N O PF : C, 45.94; H, 5.06; N,
2
1,674.01 cm . H NMR (300.13 MHz, CDCl ), d 1.93 (p,
1
6
21
2
6
3
6
.70. Found: C, 45.87; H, 5.13; N, 6.71 %.
4 H, NCH CH CH CH N); 2.45 (s, 6 H, CH ); 3.69 (t, 4 H,
2
2
2
2
3
J 5.7 Hz, NCH CH CH CH N); 4.73 (s, 4 H, NCH -thio-
2
2
2
2
2
1
,3-Di(5-methylthiophen-2-ylmethyl)pyrimidinium
phene); 6.63–6.95 (m, 4 H, thiophene-H); 7.90 (s, 1 H,
3
1
hexafluorophosphate, 2b
2-CH). C NMR (75.47 MHz, CDCl ), d 15.5 (NCH
3
2-
CH CH CH N); 24.5 (CH ); 49.1 (NCH CH CH CH N);
2
2
2
2
3
2
2
2
Yield: 78 %; m.p.: 182–183 ꢁC; IR: t(C=N):
56.3 (NCH -thiophene); 125.7, 129.5, 132.7 and 142.4
2
-
1 1
1
,504.49 cm . H NMR (300.13 MHz, DMSO), d 1.88 (p,
H, J 5.4 Hz, NCH CH CH N); 2.44 (s, 6 H, CH ); 3.26
(thiophene-C); 157.1 (2-CH). Anal. Calcd. for C H N
7 23 2-
1
2
S PF : C, 43.96; H, 4.99; N, 6.03. Found: C, 44.05; H,
2
2
2
2
3
6
(
t, 4 H, J 5.6 Hz, NCH CH CH N); 4.78 (s, 4 H,
2
4.89; N, 6.06 %.
2
2
1
23

J IRAN CHEM SOC
Table 3 Crystal data collection
and refinement for
˚
V = 1,024.69 (8) A
3
C
16
H
21
N
2
S
2
ꢀF
= 450.46
Triclinic, P - 1
6
P
M
r
Z = 2
C
16 21 2
H N S
2
ꢀF
6
P (2b)
-3
D
x
= 1.460 Mg m
˚
a = 9.3159 (4) A
Mo Ka radiation
˚
b = 10.9300 (5) A
Cell parameters from 285 reflections
˚
c = 11.2445 (5) A
h = 3.2–21.4ꢁ
l = 0.39 mm
T = 296 (2) K
-
1
a = 63.522 (2)ꢁ
b = 89.012 (2)ꢁ
c = 89.691 (2)ꢁ
Bruker Kappa APEXII CCD diffractometer
Prism, light yellow
2,892 reflections with I [ 2r (I)
x scan
R
int = 0.021
Absorption correction: multi-scan (based on
symmetry-related measurements)
hmax = 25.3ꢁ
Tmin = 0.889, Tmax = 0.913
h = -11 ? 10
1
3,992 measured reflections
k = -13 ? 12
3
,655 independent reflections
2
l = -13 ? 13
Refinement on F
2
R[F [ 2r(F )] = 0.068
H atoms constrained to parent site
2
Calculated weights w = 1/
2
2
2
[
r (F ) ? (0.134P) ? 0.7188P] where
o
2
2
o c
P = (F ? F )/3
2
wR(F ) = 0.227
(D/r)max \ 0.0001
-1
˚
S = 1.06
Dqmax = 0.94 e A
-
1
˚
3
2
,655 reflections
74 parameters
Dqmin = -0.42 e A
Extinction correction: none
1
,3-Di(N-methylpyrrol-2-ylmethyl)diazepinium
X-ray crystallographic studies
hexafluorophosphate, 3c
A suitable crystal of 2b for X-ray diffraction was obtained
by slow diffusion of dichloromethane into diethylether
solutions at room temperature. Data collection: APEX2
[34]; cell refinement: SAINT [34]; data reduction: SAINT
[29]. Program(s) used to solve structure: SHELXS97 [35].
Program(s) used to refine structure: SHELXL97 [35].
Molecular graphics: ORTEP-3 for Windows [36] and
PLATON [37]. Software used to prepare material for
publication: WinGX [38] and PLATON [37]. The data
collection, details of the X-ray structure determination and
refinement for 2b are given in Table 3.
-
1
Yield: 80 %; m.p.: 92–93 ꢁC; IR: t(C=N): 1,585.99 cm
.
1
H NMR (300.13 MHz, CDCl ), d 1.94 (p, 4 H, J 5.5 Hz,
NCH CH CH CH N); 3.55 (s, 6 H, CH ); 3.67 (t, 4 H,
2
3
2
2
2
3
J 5.4 Hz, NCH CH CH CH N); 4.61 (s, 4 H, CH C H
2 4 3-
2
2
2
2
NCH ); 6.06–6.67 (m, 6 H, pyrrol-H); 7.62 (s, 1 H, 2-CH).
3
1
3
C NMR (75.47 MHz, CDCl ), d 24.5 (NCH CH CH
CH N); 33.8 (CH ); 48.6 (NCH CH CH CH N); 52.7
2
3
2
2
2-
3
2
2
2
2
(
CH C H NCH ); 107.7, 112.4, 122.9 and 125.2 (Pyrrol-
2 4 3 3
C); 156.6 (2-CH). Anal. Calcd. for C H N PF : C, 47.44;
1
7
25
4
6
H, 5.86; N, 13.02. Found: C, 47.51; H, 5.79; N, 13.00 %.
General procedure for the Mizoroki–Heck coupling
reaction
Conclusions
Heterocyclic salts 1–3 (2.0 mmol), Pd(OAc) (1.0 mmol),
2
In this work, newly designed heteroaryl-substituted het-
erocyclic salts were successfully synthesized and fully
characterized. Also, using single-crystal X-ray diffraction,
we determined the structures in the solid state of compound
2b. An easy to handle, highly effective and environmen-
tally benign process was developed for palladium-mediated
Mizoroki–Heck coupling reactions. In addition, the newly
synthesized nine salts were successfully used in this cou-
pling reaction. A significant influence of the reaction
t
aryl bromide (1.0 mmol), styrene (1.5 mmol), KOBu
(
2.0 mmol), H O (3 mL) and DMF (3 mL) were added to a
2
small Schlenk tube and the mixture was heated to 80 ꢁC for
h. After the reaction was completed, the mixture was
1
extracted with ethylacetate, and purified by flash chroma-
tography on silica gel. The purity of the compounds was
checked by NMR and GC. Yields are based on aryl
bromide.
123

J IRAN CHEM SOC
temperature and time was observed on the catalytic activity
of the synthesized salts. The best results were obtained for
the salt 3c while all of the salts were found to be catalyt-
ically active.
15. D. Munz, C. Allolio, K. D o¨ ring, A. Poethig, T. Doert, H. Lang
et al., Inorg. Chim. Acta 392, 204 (2012)
1
1
6. V. Farina, Adv. Synth. Catal. 346, 1553 (2004)
¨
˙
7. I. Ozdemir, N. G u¨ rb u¨ z, Y. G o¨ k, B. C¸ etinkaya, Heteroatom Chem.
19, 82 (2008)
1
8. W.A. Herrmann, B. Cornils, W.A. Herrmann, Applied homoge-
neous catalysis with organometallic compounds (Wiley-VCH,
Weinheim, 1996)
Acknowledgments This work was financially supported by In o¨ n u¨
University Research Fund (I.U.B.A.P. 2011/130).
The authors acknowledge the provision of funds for the purchase of
a diffractometer and encouragement by Dr Muhammad Akram
Chaudhary, Vice Chancellor, University of Sargodha, Pakistan.
Supplementary data
CCDC 927101 contains the supplementary crystallographic data
for this paper. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (?44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
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