Use of tetrahydropyrimidinium salts for highly efficient palladium-catalyzed cross-coupling reactions of aryl bromides and chlorides

Article abstract of DOI:10.1016/j.tet.2005.06.064

New, sterically demanding 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (2) as NHC precursors have been synthesized and characterized. These salts, in combination with palladium acetate, provided active catalysts for the cross-coupling of aryl chloride

Full text of DOI:10.1016/j.tet.2005.06.064

Tetrahedron 61 (2005) 9791–9798
Use of tetrahydropyrimidinium salts for highly efficient
palladium-catalyzed cross-coupling reactions of aryl bromides
and chlorides
a,
a
Ismail Ozdemir, Serpil Demir and Bekir C¸ etinkaya
b
¨
*
a
¨ ¨
Department of Chemistry, Inonu Universityt, 44280 Malatya, Turkey
bDepartment of Chemistry, Ege University, 35100 Bornova-Izmir, Turkey
Received 4 March 2005; revised 6 May 2005; accepted 10 June 2005
Available online 9 August 2005
Abstract—New, sterically demanding 1,3-dialkyl-3,4,5,6-tetrahydropyrimidinium salts (2) as NHC precursors have been synthesized and
characterized. These salts, in combination with palladium acetate, provided active catalysts for the cross-coupling of aryl chlorides and bromides
undermildconditions.ThecatalyticsystemwasappliedtotheHeck, Suzukiand benzaldehyde (Kumada)couplingreactions. Catalystactivity was
found to be influenced by the presence of a methoxy group on the ring of the p-position of benzyl substituent of the ligand precursor.
q 2005 Elsevier Ltd. All rights reserved.
1. Introduction
Research in this area was principally driven by the
employment of these complexes as potential catalysts.
Many catalytic applications of NHC complexes have been
described.7–9 Palladium-catalyzed cross-coupling reactions
are particularly attractive because of their versatility in the
formation of C–C and C–X bonds (XZO, S, N etc.).10–13
The main advantages of these coupling processes stems
from the readily availability of starting materials and the
broad tolerance of palladium catalysts to various functional
groups. Pd-catalyzed cross-coupling reactions are generally
thought to proceed through three distinctive steps:14 (i) an
aryl halide reacts with Pd(0) through oxidative addition to
give an electrophilic Pd(II) species. (ii) A transmetallation
reaction then occurs with an appropriate nucleophile to
yield a Pd(II) complex, containing the two moieties to be
coupled. (iii) Reductive elimination of the product, which
regenerates the active Pd(0) species.
Transition metal complexes incorporating 1,3-diorganyl N-
heterocyclic carbene (NHC) ligands, such as imidazol-2-
ylidene (AZCH]CH), imidazolidin-2-ylidene (AZ
CH2CH2) and benzimidazol-2-ylidene (AZC6H4-o) have
attracted a great interest in recent years.1–6 They are often
synthesized by reaction of an azolinium salt (LHX) with a
basic salt such as Pd(OAc)2, to give M(NHC)Lm.
The ancillary ligand (NHC) coordinated to the metal center
has a number of important roles in homogeneous catalysis
such as providing a stabilizing effect and governing the
activity and selectivity through alteration of the steric and
electronic parameters. The number, nature and position of
the substituents on the nitrogen atom(s) and/or NHC ring
have been found to play a crucial role in tuning the catalytic
activity. Whilst modifications to the five-membered ring of
the ligand aryl substituent have been described, relatively
little attention has been paid to the effect of the ring size.15
For the present study, we selected 3,4,5,6-tetrahydopyr-
imidin-2-ylidene precursors (2). This choice was guided by
several considerations. An important characteristic of the
carbene ligands in active complexes is their strong-electron
Keywords: N-Heterocyclic carbene; Suzuki coupling.
*
Corresponding author. Tel.: C90 4223410010; fax: C90 4223410037;
e-mail: iozdemir@inonu.edu.tr
0040–4020/$ - see front matter q 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2005.06.064

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9792
donating effect, primarily a s-effect. We have previously
reported the use of a in situ formed imidazolidin-2-
ylidenepalladium(II) system, which exhibits high activity
in various coupling reactions of aryl bromides and aryl
chlorides.16 In order to obtain a more stable, efficient and
active system, we have also investigated benzo-annelated
derivatives.17 Due to their six-membered ring geometry,
tetrahydopyrimidine-2-ylidenes are stronger s-donating
ligands in comparison to their five-membered relatives.15
50 8C led to the best conversion within 5 h. We initially
evaluated the catalytic activity of Pd(OAc)2/2a for the
coupling of bromobenzene with styrene (Table 1, entry 1).
Control experiments indicate that the coupling reaction did
not occur in the absence of 2a. Under these reaction
conditions a wide range of aryl bromides bearing electron-
donating or electron-withdrawing groups react with styrene
affording the coupled products in excellent yields. As
expected, electron-deficient bromides coupled well under
the conditions. Enhancement in activity, although less
significant, is further observed employing 4-bromobenzal-
dehyde instead of 4-bromoacetophenone (entries 16–20 and
21–25, respectively).
2. Results and discussion
2.1. Synthesis and characterization of the salts, 2
The synthesis of the tetrahydropyrimidinium chlorides was
achieved via two synthetic routes (Scheme 1). The
alkylation of 1-alkyltetrahydropyrimidine derivatives18
with alkyl chlorides produced symmetrical or unsymme-
trical 1,3-dialkylpyrimidinium salts (Route A). On the other
hand, reaction of N,N0-dialkylpropan-1,3-diamine with
triethyl orthoformate and ammonium chloride yielded the
symmetrical tetrahydropyrimidinium salt (Route B)
(Scheme 1).
A systematic study on the substituent effect in the
tetrahydropyrimidinium salts 2 indicated that the introduc-
tion of a methoxy group to the p-position of the benzyl
substituent on the N-atoms notably increased the reaction
rate and the yield of the coupled product. The catalytic
activity of the salts used fall in the order of cObOdOaOe.
The ether functionality in 2e does not contribute with any
great effect as seen with the arylation of benzaldehyde
derivatives (see Section 2.4). These results indicated that the
catalytic system generated in situ from tetrahydropyrimidi-
nium salts and Pd(OAc)2 have an activity, which is superior
Elemental analysis and 1H and 13C NMR spectra confirmed
the formation of 2 (see Section 4). An important feature of
the ligand precursors (2) is their facile preparation. While
these studies were in progress, other workers have addressed
the synthesis and catalytic properties of 1,3-dimesitylte-
trahydropyrimidine-2-ylidene complexes of palladium.19,20
Contrary to the claims made by Buchmeister and co-
workers,19a and unlike other silver NHC complexes, it has
been reported that the chlorodimesityltetrahydrpyrimidin-2-
ylidenesilver does not transfer the carbene ligand to
Pd(NCCH3)2Cl2 to afford Pd(NHC)2Cl2.20
Table 1. Pd-catalyzed Heck coupling
Entry
LHCl
R
Yield (%)a–c
1
2
3
4
5
6
7
8
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
H
H
H
H
80
88
89
85
78
88
87
88
90
80
84
90
92
83
80
90
88
92
85
84
91
94
96
87
85
2.2. The Heck reaction
The Heck alkenylation reaction21 is useful approach to the
preparation of disubstituted olefins. The rate of coupling is
dependent on a variety of parameters such as temperature,
solvent, base and catalyst loading. Generally, Heck
reactions conducted with tertiary phosphine22 or NHC9,23
complexes require high temperatures (higher than 120 8C)
and polar solvents. For the choice of base, we chose to use
Cs2CO3, K2CO3, and K3PO4. Finally, use of 1.5% mol
Pd(OAc)2, 3% mol 2, 2 equiv Cs2CO3 in DMF/H2O (1:1) at
H
OCH3
OCH3
OCH3
OCH3
OCH3
CH3
CH3
CH3
CH3
CH3
COCH3
COCH3
COCH3
COCH3
COCH3
CHO
CHO
CHO
CHO
CHO
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
a Reaction conditions: 1.0 mmol of R-C6H4X-p, 1.5 mmol of styrene,
2 mmol Cs2CO3, 1.50 mmol% Pd(OAc)2, 3.0 mmol% 2, water (3 mL)-
DMF (3 mL).
b The purity of the products were confirmed by NMR and yields are based
on aryl bromide.
c 50 8C, 5 h.
Scheme 1. Synthesis of ligand precursors.

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9793
or comparable to the imidazolinium/Pd(OAc)2 system.16
However, chloroarenes do not react under standard
conditions; yields of !5% were recorded.
The scope of the reaction with respect to the aryl chloride
component was also investigated. It can be seen that 2c is an
effective ligand precursor for the coupling of unactivated,
activated and deactivated chlorides (entries 1–25). With
chlorobenzene, 4-chloroanisole, 4-chloroacetophenone and
4-chlorobenzaldehyde, a similar activity sequence was
observed: cObOdOaOe.
2.3. The Suzuki coupling
Suzuki cross-coupling represents a powerful method for
carbon–carbon bond formation.24 Recently, the reaction of
aryl chlorides catalyzed by palladium/tertiary phosphine22
and palladium/NHC25–28 systems have been extensively
studied due to the economically attractive nature of the
starting materials and the production of the less toxic salt
by-products, for example, NaCl as opposed to NaBr. Here,
various tetrahydropyrimidinium salts (2a–e) were compared
as ligand precursors under the same reaction conditions. To
survey the parameters for Suzuki coupling, we chose to
examine Cs2CO3, K2CO3, and K3PO4 as base and DMF/
H2O (1:1) and dioxane as the solvent mixture. We found
that the reactions performed in DMF/H2O (1:1) with
Cs2CO3 or K2CO3 at 50 8C appeared to be best. We
initiated our investigation with coupling of chlorobenzene
and phenylboronic acid, in the presence of Pd(OAc)2/2.
Table 2 summarizes the results obtained in the presence of
2a–e (Table 2, entries 1–5).
In summary, we have demonstrated that in situ generated
tetrahydropyrimidin-2-ylidene complexes of palladium are
effective catalyst systems for Suzuki cross-coupling,
surpassing the catalytic activity observed with the corre-
sponding imidazolidin-2-ylidene palladium complexes.
2.4. Arylation of benzaldehyde derivatives
Another interesting cross-coupling process (Miura reaction)
is palladium-catalyzed o-arylation(s) of benzaldehyde
derivatives with aryl halides providing 2- or 2,6-diarylbenz-
aldehydes.29 Using similar reaction conditions, we investi-
gated the arylation of benzaldehyde derivatives using in situ
generated palladium complexes of tetrahydropyrimidine-2-
ylidene derived from 2. The results are summarized in
Table 3.
Here, 2e is one of the best ligand precursors for the reaction
of aryl chlorides. The use of cesium carbonate as the base in
dioxane produced good to excellent yields of the correspond-
ing products. The selectivity for mono- or di-arylation can be
shifted to some extent by judicious choice of halide X, that is,
for XZCl, only the monoarylated product is seen; whereas
for XZBr; the 2,6-diarylated product is formed predomi-
nantly when the aldehyde/aryl bromide ratio is 1:2.
Table 2. Pd-catalyzed Suzuki coupling
Entry
LHCl
R
Yield (%)a–d
1
2
3
4
5
6
7
8
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
H
H
H
H
93
89
93
85
81
88
90
92
87
72
87
91
94
85
83
96
96
98
94
91
94
94
95
90
84
3. Conclusions
We have shown that amongst the various saturated NHC
precursors, tetrahydopyrimidinium salts (2) are excellent
ligand precursors for the direct functionalization of aryl
halides, in particular, aryl chlorides. The Heck, Suzuki and a
variant of the Miura reaction of aryl bromides and chlorides
have been investigated in the presence of a Pd(OAc)2/2
catalyst system. The cross-coupling results obtained using
the Pd(OAc)2/2 mixture do not necessarily indicate a
palladium carbene complex as the active catalyst species.
Good to excellent yields of the desired products were
obtained for the benchmark reactions in this study. In
general, the 2c catalyst system appears to be more efficient
for the Heck reactions of aryl bromides; the activity is lower
for the coupling of aryl chlorides. On the other hand, the
catalyst 2e work well in a version of Miura coupling of aryl
chlorides.
H
OCH3
OCH3
OCH3
OCH3
OCH3
CH3
CH3
CH3
CH3
CH3
COCH3
COCH3
COCH3
COCH3
COCH3
CHO
CHO
CHO
CHO
CHO
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Clearly, 1,3-dialkyltetrahydropyrimidin-2-ylidene palla-
dium complexes are superior when compared to the
corresponding 1,3-dialkylimidazolidin-2-ylidene palladium
complexes. Once again, we observed that the in situ formed
Pd–NHC catalysts, which consist of mixtures of palladium
and ligands, gave better yields in the coupling reactions
compared to the isolated carbene palladium(II) complexes.
a Reactions conditions: 1.0 mmol of R-C6H4Cl-p, 1.2 mmol of phenyl-
boronic acid, 2 mmol K2CO3, 1.5 mmol% Pd(OAc)2, 3 mmol% 2, water
(3 mL)–DMF (3 mL).
b The purity of the products was confirmed by NMR and yields are based on
aryl chloride.
c All reactions were monitored by GC.
d 50 8C, 2 h.

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9794
Table 3. Arylation of benzaldehyde derivatives
Entry
Ar–X
Aldehyde
Product
LHCl
Time (h)
Yielda–d (%)
1
2
3
4
5
6
7
8
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3CO)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
5
5
5
5
5
5
89
92
86
96
93
90
87
93
84
89
95
87
91
93
97
90
92
89
95
97
76
79
83
78
84
83
77
82
86
85
90
89
82
86
92
88
88
91
95
98
79
70
74
74
81
90
85
80
83
92
2-(p-Acetylphenyl)-3,4,5-
(trimethoxy)benzal-
dehyde
3,4,5-Trimethoxy benzaldehyde
3,4,5-Trimethoxy benzaldehyde
p-Methoxy benzaldehyde
p-Methoxy benzaldehyde
Benzaldehyde
24
20
24
24
20
24
24
24
24
10
10
10
10
10
24
24
24
24
24
10
10
10
10
10
15
24
24
24
15
5
2-(p-Methoxyphenyl)-3,4,
5-(trimethoxy)benzal-
dehyde
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
2-(p-Methoxyphenyl)-4-
methoxybenzaldehyde
2-(p-Acetylphenyl)-4-
methoxybenzaldehyde
2-(p-Methoxyphenyl)
benzaldehyde
2-(p-Acetylphenyl)-4-
tert-butylbenzaldehyde
p-(tert-Butyl) benzaldehyde
p-(tert-Butyl) benzaldehyde
p-Dimethylaminobenzaldehyde
p-Dimethylaminobenzaldehyde
p-Methoxy benzaldehyde
2-(p-Methoxyphenyl)-4-
tert-butylbenzaldehyde
5
5
5
5
2-(p-Acetylphenyl)-4-
dimethylamino benzal-
dehyde
28
28
28
36
36
12
12
12
12
12
2-(p-Methoxyphenyl)-4-
dimethylamino benzal-
dehyde
2,6-Bis(p-methoxyphe-
nyl)-4-methoxybenzalde-
hyde

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9795
Table 3 (continued)
Entry
Ar–X
Aldehyde
Product
LHCl
Time (h)
Yielda–d (%)
51
52
53
54
55
56
57
58
59
60
61
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
4-(CH3O)–C6H4–
2a
2b
2c
2d
2e
2a
2b
2c
2d
2e
2e
12
12
12
12
12
12
12
12
12
12
12
86
80
89
85
91
83
85
87
82
88
91
2,6-Bis(p-methoxyphe-
nyl)-4-dimethylamino
benzaldehyde
p-Dimethylami-nobenzaldehyde
2,6-Bis(p-methoxyphe-
nyl)-4-tert-butylbenzalde-
hyde
p-(tert-Butyl) benzaldehyde
2,5-Bis(p-methoxyphe-
nyl) terephtalaldehyde
Terephtalaldehyde
a For entries 46–61, aryl bromides (2 equiv) were used as aryl halide. In all other cases aryl chlorides were used.
b Reactions conditions: 1.0 mmol of R–C6H4Cl-p, 1.0 mmol of aldehyde, 2 mmol Cs2CO3, 1.0 mmol% Pd(OAc)2, 2 mmol% 1,3-dialkyl pyrimidinium salt 2,
dioxane (3 mL), 80 8C.
c The purity of the products was confirmed by NMR and yields are based on aldehyde.
d All reactions were monitored by TLC.
4. Experimental
C24H33N2Cl: C, 74.87; H, 8.64; N, 7.27. Found: C, 74.83; H,
8.66; N, 7.30.
4.1. General
4.1.2. Preparation of 1,3-bis(2,4,6-trimethoxybenzyl)-3,
4,5,6-tetrahydropyrimidinium chloride (2b). Compound
2b was prepared in the same way as 2a from N,N0-bis(2,4,6-
trimethoxybenzyl)propane (4.34 g, 10 mmol), NH4Cl
(0.53 g, 10 mmol) in triethyl orthoformate (50 mL) to give
All reactions for the preparation of 1,3-dialkylpyrimidinium
salts were carried out under argon using standard Schlenk
flasks. Test reactions for the catalytic activity of palladium
catalysts in the Suzuki and Heck cross-coupling reactions
were carried out in the presence of air. All reagents were
purchased from Aldrich Chemical Co. The solvents, Et2O
over Na, DMF over BaO, EtOH over Mg were distilled prior
white crystals of 2b 4.27 g (89%). Mp 233–234 8C, n(CN)
Z
1682 cmK1. H NMR (300.13 MHz, CDCl3) d 7.82 (s, 1H,
NCHN), 6.03 (s, 4H, CH2C6H2(OCH3)3-2,4,6), 4.46 (s, 4H,
CH2C6H2(OCH3)3-2,4,6), 3.69 and 3.75 (s, 18H, CH2C6-
H2(OCH3)3-2,4,6), 3.32 (t, JZ5.6 Hz, 4H, NCH2CH2CH2-
N), 1.96 (quint, JZ5.2 Hz, 2H, NCH2CH2CH2N). 13C NMR
(75.47 MHz, CDCl3) d 162.7 (NCHN), 90.8, 101.7, 151.8
and 159.9 (CH2C6H2(OCH3)3-2,4,6), 58.1 (CH2C6H2
(OCH3)3-2,4,6), 55.7 and 56.1 (CH2C6H2(OCH3)3-2,4,6),
43.3 (NCH2CH2CH2N), 19.4 (NCH2CH2CH2N). Anal.
Calcd for C24H33N2O6Cl: C, 59.93; H, 6.91; N, 5.82.
Found: C, 59.89; H, 6.94; N, 5.80.
1
1
to use. All H and 13C NMR spectra were performed in
1
CDCl3. H and 13C NMR spectra were recorded using a
Bruker AC300P FT spectrometer operating at 300.13 MHz
(1H), 75.47 MHz (13C). Chemical shifts (d) 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 cmK1. Melting points were measured in open
capillary tubes with an Electrothermal-9200 melting point
apparatus and uncorrected. Elemental analyses were
performed by TUBITAK (Ankara, Turkey) Microlab.
4.1.3. Preparation of 1,3-bis(3,4,5-trimethoxybenzyl)-3,
4,5,6-tetrahydropyrimidinium chloride (2c). Compound
2c was prepared in the same way as 2a from N,N0-bis(3,4,5-
trimethoxybenzyl)propane (4.34 g, 10 mmol), NH4Cl
(0.53 g, 10 mmol) in triethyl orthoformate (50 mL) to give
4.1.1. Preparation of 1,3-bis(2,4,6-trimethylbenzyl)-3,4,
5,6-tetrahydropyrimidinium chloride (2a). A mixture of
N,N0-bis(2,4,6-trimethylbenzyl)propane (3.38 g, 10.0 mmol),
NH4Cl (0.53 g, 10.0 mmol) in triethyl orthoformate (50 mL)
was heated in a distillation apparatus until the distillation of
ethanol ceased. The temperature of the reaction mixture
reached 110 8C. Upon cooling to rt, a colorless solid
precipitated, which was collected by filtration, and dried in
vacuum. The crude product was recrystallized from absolute
ethanol to give colorless needles, and the solid was washed
with diethyl ether (2!10 mL), dried under vacuum, and
white crystals of 2c 4.51 g (94%). Mp 266–267 8C, n(CN)
Z
1701 cmK1. 1H NMR (300.13 MHz, CDCl3) d 10.43 (s, 1H,
NCHN), 6.72 (s, 4H, CH2C6H2(OCH3)3-3,4,5), 4.75 (s, 4H,
CH2C6H2(OCH3)3-3,4,5), 3.76 and 3.81 (s, 18H, CH2C6-
H2(OCH3)3-3,4,5), 3.21 (t, JZ5.2 Hz, 4H, NCH2CH2CH2N),
1.93 (quint, JZ5.2 Hz, 2H, NCH2CH2CH2N). 13C NMR
(75.47 MHz, CDCl3) d 154.7 (NCHN), 106.6, 129.0, 138.7
and 153.9 (CH2C6H2(OCH3)3-3,4,5), 61.0 (CH2C6H2
(OCH3)3-3,4,5), 56.8 and 59.0 (CH2C6H2(OCH3)3-3,4,5),
42.0 (NCH2CH2CH2N), 19.3 (NCH2CH2CH2N). Anal.
Calcd for C24H33N2O6Cl: C, 59.93; H, 6.91; N, 5.82.
Found: C, 59.95; H, 6.90; N, 5.84.
the yield was 3.77 g (98%). Mp 288–289 8C, n(CN)
Z
1
1688 cmK1. H NMR (300.13 MHz, CDCl3) d 8.56 (s, 1H,
NCHN), 6.73 (s, 4H, CH2C6H2(CH3)3-2,4,6), 4.74 (s, 4H,
CH2C6H2(CH3)3-2,4,6), 3.36 (t, JZ5.7 Hz, 4H, NCH2CH2-
CH2N), 2.16 and 2.20 (s, 18H, CH2C6H2(CH3)3-2,4,6), 2.01
(quint, JZ5.3 Hz, 2H, NCH2CH2CH2N). 13C NMR
(75.47 MHz, CDCl3) d 151.9 (NCHN), 125.3, 130.0, 137.9
and 138.9 (CH2C6H2(CH3)3-2,4,6), 52.1 (CH2C6H2(CH3)3-
2,4,6), 42.6 (NCH2CH2CH2N), 19.8 and 20.9 (CH2C6H2
(CH3)3-2,4,6), 19.1 (NCH2CH2CH2N). Anal. Calcd for
4.1.4. Preparation of 1-(2,4,6-trimethylbenzyl)-3-cyclo-
hexyl-(3,4,5,6-tetrahydropyrimidinium chloride (2d). To
a solution of 1-cyclohexyl(3,4,5,6-tetrahydropyrimidine)
(1.66 g, 10 mmol) in DMF (10 mL) was added slowly
2,4,6-trimethylbenzyl chloride (1.68 g, 10.1 mmol) at 25 8C

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9796
and the resulting mixture was stirred at rt for 5 h. Diethyl
ether (15 mL) was added to obtain a white crystalline solid,
which wasfiltered off. The solid waswashedwithdiethyl ether
(3!15 mL), dried under vacuum, and the yield was 3.07 g
ether, then concentrated in vacuo and purified by flash
chromatography on silica gel. The purity of the compounds
was confirmed by NMR spectroscopy and yields are based
the on aryl halide.
(92%). Mp 210–211 8C. n(CN)Z1682 cmK1 1H NMR
.
(300.13 MHz, CDCl3) d 9.50 (s, 1H, NCHN), 6.60 (s, 4H,
CH2C6H2(CH3)3-2,4,6), 4.81 (s, 4H, CH2C6H2(CH3)3-2,4,6),
3.50 (quint, JZ8.2 Hz, 1H, NCH(CH2)4CH2), 3.19 and 2.87
(t, JZ5.6 Hz, 4H, NCH2CH2CH2N), 2.01 and 2.07 (s, 9H,
CH2C6H2(CH3)3-2,4,6), 1.39 (m, 10H, NCH(CH2)4CH2),
1.79 (quint, JZ5.3 Hz, 2H, NCH2CH2CH2N). 13C NMR
(75.47 MHz, CDCl3) d 153.0 (NCHN), 125.6, 129.7, 137.9
and 138.5 (CH2C6H2(CH3)3-2,4,6), 64.0 (CH2C6H2(CH3)3-
2,4,6), 51.9 (NCH(CH2)4CH2), 40.2 and 41.2 (NCH2CH2-
CH2N), 24.5, 24.9 and 30.8 (NCH(CH2)4CH2), 20.2 and
20.8 (CH2C6H2(CH3)3-2,4,6), 19.2 (NCH2CH2CH2N).
Anal. Calcd for C20H31N2Cl: C, 71.72; H, 9.33; N, 8.36.
Found: C, 71.71; H, 9.35; N, 8.40.
4.4. General procedure for the arylation of benzaldehyde
reaction
A dried Schlenk flask equipped with a magnetic stirring bar
was charged with the aldehyde (1.0 mmol), aryl chloride
(1.0 mmol), Pd(OAc)2 (0.01 mmol), 1,3-dialkyl(3,4,5,6-
tetrahydropyrimidinium)chloride, 2 (0.02 mmol), Cs2CO3
(2.0 mmol) and dioxane (3 mL). After stirring at 80 8C for
5–24 h, the mixture was cooled to rt and then quenched by
addition of aqueous 1 N HCl and extracted with diethyl
ether. The organic layer was dried over MgSO4, filtered,
then concentrated in vacuo and purified by column
chromatography on silica gel eluting with ethyl acetate/
hexane (1:5). Analysis of the reaction product was carried
out by NMR spectroscopy and GC–MS.
4.1.5. Preparation of 1-methoxyethyl-3-(2,4,6-trimethyl-
benzyl)-3,4,5,6-tetrahydropyrimidinium chloride (2e).
Compound 2e was prepared in the same way as 2d from
1-methoxyethyl(3,4,5,6-tetrahydropyrimidine) (1.42 g,
10 mmol) and 2,4,6-trimethylbenzyl chloride (1.68 g,
10.1 mmol) to give white crystals of 2e 2.69 g (87%). Mp
4.4.1. 2-(p-Acetylphenyl)-3,4,5-(trimethoxy)benzal-
dehyde. Colourless oil, n(C]O)Z1708 cmK1 1H NMR
.
(300.13 MHz, CDCl3) d 9.80 (s, 1H, 2-C6H4(p-COCH3)
C6H(OCH3)3-3,4,5CHO), 7.85 and 7.48 (d, JZ2.5 Hz, 4H,
2-C6H4(p-COCH3)C6H(OCH3)3-3,4,5CHO), 7.06 (s, 1H,
2-C6H4(p-COCH3)C6H(OCH3)3-3,4,5CHO), 3.89 and 3.88
(s, 9H, 2-C6H4(p-COCH3)C6H(OCH3)3-3,4,5CHO), 2.54 (s,
3H, 2-C6H4(p-COCH3)C6H(OCH3)3-3,4,5CHO). 13C NMR
118–119 8C, n(CN)Z1688 cmK1 1H NMR (300.13 MHz,
.
CDCl3) d 9.26 (s, 1H, NCHN), 6.80 (s, 4H, CH2C6H2
(CH3)3-2,4,6), 4.84 (s, 4H, CH2C6H2(CH3)3-2,4,6), 3.26 (s,
3H, CH2CH2OCH3), 3.77 (t, JZ4.5 Hz, 2H, CH2CH2-
OCH3), 3.49 (t, JZ4.7 Hz, 2H, CH2CH2OCH3), 3.12 and
3.36 (t, JZ5.7 Hz, 4H, NCH2CH2CH2N), 2.19 and 2.25 (s,
9H, CH2C6H2(CH3)3-2,4,6), 2.00 (quint, JZ5.6 Hz, 2H,
NCH2CH2CH2N). 13C NMR (75.47 MHz, CDCl3) d 153.9
(NCHN), 125.2, 129.7, 138.0 and 138.9 (CH2C6H2(CH3)3-
2,4,6), 69.1 (CH2C6H2(CH3)3-2,4,6), 58.8 (CH2CH2OCH3),
54.2 (CH2CH2OCH3), 52.2 (CH2CH2OCH3), 43.9 and 41.3
(NCH2CH2CH2N), 19.8 and 20.8 (CH2C6H2(CH3)3-2,4,6),
19.0 (NCH2CH2CH2N). Anal. Calcd for C17H27N2OCl: C,
65.68; H, 8.75; N, 9.01. Found: C, 65.65; H, 8.73; N, 9.00.
(75.47 MHz, CDCl3)
d
188.9 (2-C6H4(p-COCH3)
C6H(OCH3)3-3,4,5CHO), 108.2, 121.4, 126.7, 127.2, 127.9,
128.7, 130.1, 132.3, 136.7 and 154.5 (2-C6H4(p-COCH3)
C6H(OCH3)3-3,4,5CHO),
C6H(OCH3)3-3,4,5CHO), 54.1 and 54.6 (2-C6H4(p-COCH3)
C6H(OCH3)3-3,4,5CHO), 24.8 (2-C6H4(p-COCH3)
194.2
(2-C6H4(p-COCH3)
C6H(OCH3)3-3,4,5CHO). Anal. Calcd for C18H18O5: C,
68.78; H, 5.77. Found: C, 68.75; H, 5.80.
4.4.2. 2-(p-Methoxyphenyl)-3,4,5-(trimethoxy)benzal-
dehyde. Colourless crystals. Mp 65–66 8C, n(C]O)
Z
1
4.2. General procedure for the Heck coupling reaction
1716 cmK1. H NMR (300.13 MHz, CDCl3) d 9.85 (s, 1H,
2-C6H4(p-OCH3)C6H(OCH3)3-3,4,5CHO), 7.21 and 6.79
(d, JZ4.7 Hz, 4H, 2-C6H4(p-OCH3)C6H(OCH3)3-3,4,
5CHO), 7.11 (s, 1H, 2-C6H4(p-OCH3)C6H(OCH3)3-3,4,
5CHO), 3.91 and 3.92 (s, 9H, 2-C6H4(p-OCH3)
C6H(OCH3)3-3,4,5CHO), 3.76 (s, 3H, 2-C6H4(p-OCH3)
C6H(OCH3)3-3,4,5CHO). 13C NMR (75.47 MHz, CDCl3) d
189.2 (2-C6H4(p-OCH3)C6H(OCH3)3-3,4,5CHO), 113.7,
123.8, 124.5, 125.1, 127.6, 128.2, 129.0, 130.3, 132.7 and
156.8 (2-C6H4(p-OCH3)C6H(OCH3)3-3,4,5CHO), 54.3
and 54.8 (2-C6H4(p-OCH3)C6H(OCH3)3-3,4,5CHO), 53.7
(2-C6H4(p-OCH3)C6H(OCH3)3-3,4,5CHO). Anal. Calcd for
C17H18O5: C, 67.54; H, 6.00. Found: C, 67.51; H, 6.04.
Pd(OAc)2 (1.0 mmol%), 1,3-dialkyl(3,4,5,6-tetrahydropyri-
midinium) chloride, 2 (2 mmol%), aryl chloride (1.0 mmol),
styrene (1.5 mmol), C2CO3 (2 mmol) and water (3 mL)/
DMF (3 mL) were added to a small Schlenk tube and the
mixture heated to 50 8C for 5 h. At the conclusion of the
reaction, the mixture was cooled, extracted with ethyl
acetate/hexane (1:5), filtered through a pad of silica gel with
copious washings ether, the filtrate concentrated in vacuo to
afford a solid, which was purified by flash chromatography
on silica gel. The purity of the compounds was confirmed by
NMR spectroscopy and yields are based on the aryl halide.
4.3. General procedure for Suzuki coupling
4.4.3. 2-(p-Methoxyphenyl)-4-methoxybenzaldehyde.
1
Colourless oil, n(C]O)Z1708 cmK1. H NMR (300.13 MHz,
Pd(OAc)2 (1.5 mmol%), 1,3-dialkyl(3,4,5,6-tetrahydropyri-
midinium) chloride, 2 (3 mmol%), aryl chloride (1.0 mmol),
phenylboronic acid (1.2 mmol), K2CO3 (2 mmol) and water
(3 mL)/DMF (3 mL) were added to a small Schlenk tube
and the mixture heated to 50 8C for 2 h. At the conclusion of
the reaction, the mixture was cooled, extracted with Et2O,
filtered through a pad of silica gel with copious washings
CDCl3) d 9.88 (s, 1H, 2-C6H4(p-OCH3)C6H3(p-OCH3)CHO),
7.66 and 7.38 (d, JZ4.9 Hz, 4H, 2-C6H4(p-OCH3)C6H3(p-
OCH3)CHO), 6.81 (m, 3H, 2-C6H4(p-OCH3)C6H3(p-OCH3)
CHO), 3.88 (s, 3H, 2-C6H4(p-OCH3)C6H3(p-OCH3)CHO),
3.77 (s, 3H, 2-C6H4(p-OCH3)C6H3(p-OCH3)3CHO). 13C
NMR (75.47 MHz, CDCl3) d 188.7 (2-C6H4(p-OCH3)
C6H3(p-OCH3)CHO), 110.8, 111.2, 112.9, 113.8, 124.1,

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9797
126.2, 130.0, 131.1, 153.1 and 157.2 (2-C6H4(p-OCH3)
C6H3(p-OCH3)CHO), 54.2 (2-C6H4(p-OCH3)C6H3(p-
OCH3)CHO), 53.8 (2-C6H4(p-OCH3)C6H3(p-OCH3)CHO).
Anal. Calcd for C15H14O3: C, 74.36; H, 5.82. Found: C,
74.40; H, 5.80.
54.4 (2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO). Anal.
Calcd for C18H20O2: C, 80.56; H, 7.51. Found: C, 80.53;
H, 7.55.
4.4.8. 2-(p-Acetylphenyl)-4-dimethylaminobenzalde-
hyde. Yellow crystals. Mp 59–60 8C, n(C]O)Z1689 cmK1
.
4.4.4. 2-(p-Acetylphenyl)-4-methoxybenzaldehyde. Col-
1H NMR (300.13 MHz, CDCl3) d 9.69 (s, 1H, 2-C6H4(p-
COCH3)C6H3(p-(CH3)2N)CHO), 7.84 and 7.68 (d, JZ
2.4 Hz, 4H, 2-C6H4(p-COCH3)C6H3(p-(CH3)2N)CHO),
6.89 (m, 3H, 2-C6H4(p-COCH3)C6H3(p-(CH3)2N)CHO),
2.54 (s, 3H, 2-C6H4(p-COCH3)C6H3(p-(CH3)2N)CHO),
3.02 (s, 6H, 2-C6H4(p-COCH3)C6H3(p-(CH3)2N)CHO).
13C NMR (75.47 MHz, CDCl3) d 189.2 (2-C6H4(p-
COCH3)C6H3(p-(CH3)2N)CHO), 109.9, 124.1, 127.8, 127.9,
128.6, 129.8, 130.8, 134.4, 138.5 and 153.3 (2-C6H4(p-
COCH3)C6H3(p-(CH3)2N)CHO), 195.7 (2-C6H4(p-COCH3)
C6H3(p-(CH3)2N)CHO), 38.9 (2-C6H4(p-COCH3)C6H3(p-
(CH3)2N)CHO), 25.4 (2-C6H4(p-COCH3)C6H3(p-(CH3)2N)
CHO). Anal. Calcd for C17H17NO2: C, 76.38; H, 6.41; N,
5.24. Found: C, 76.40; H, 6.44; N, 5.20.
ourless needles. Mp 53–54 8C, n(C]O)Z1689 cmK1 1H
.
NMR (300.13 MHz, CDCl3) d 9.78 (s, 1H, 2-C6H4(p-
COCH3)C6H3(p-OCH3)CHO), 7.87 and 7.62 (d, JZ2.5 Hz,
4H, 2-C6H4(p-COCH3)C6H3(p-OCH3)CHO), 7.82 (m, 3H,
2-C6H4(p-COCH3)C6H3(p-OCH3)CHO), 3.85(s, 3H, 2-C6H4(p-
COCH3)C6H3(p-OCH3)CHO), 2.55 (s, 3H, 2-C6H4(p-COCH3)
C6H3(p-OCH3)3CHO). 13C NMR (75.47 MHz, CDCl3) d 188.7
(2-C6H4(p-COCH3)C6H3(p-OCH3)CHO), 110.1, 123.8, 126.8,
127.4, 128.5, 130.1, 134.8, 138.1 and 155.0 (2-C6H4(p-COCH3)
C6H3(p-OCH3)CHO), 194.3 (2-C6H4(p-COCH3)C6H3(p-OCH3)
CHO), 54.4 (2-C6H4(p-COCH3)C6H3(p-OCH3)CHO), 24.9
(2-C6H4(p-COCH3)C6H3(p-OCH3)CHO). Anal. Calcd for
C16H14O3: C, 75.57; H, 5.55. Found: C, 75.60; H, 5.58.
4.4.5. 2-(p-Methoxyphenyl)benzaldehyde. Colourless oil,
.
4.4.9. 2-(p-Methoxyphenyl)-4-dimethylaminobenzalde-
n(C]O)Z1688 cmK1
1H NMR (300.13 MHz, CDCl3) d
hyde. Colourless needles. Mp 67–68 8C, n(C]O)Z
1
10.03 (s, 1H, 2-C6H4(p-OCH3)C6H4CHO), 7.24 and 6.83 (d,
JZ4.8 Hz, 4H, 2-C6H4(p-OCH3)C6H4CHO), 7.55 (m, 4H,
2-C6H4(p-OCH3)C6H4CHO), 3.78 (s, 3H, 2-C6H4(p-OCH3)
C6H4CHO). 13C NMR (75.47 MHz, CDCl3) d 192.5 (2-
C6H4(p-OCH3)C6H4CHO), 114.8, 125.2, 125.9, 126.0,
127.8, 128.3, 129.7, 130.1, 134.2 and 156.8 (2-C6H4(p-
OCH3)C6H4CHO), 53.4 (2-C6H4(p-OCH3)C6H4CHO).
Anal. Calcd for C14H12O2: C, 79.22; H, 5.70. Found: C,
79.25; H, 5.68.
1716 cmK1. H NMR (300.13 MHz, CDCl3) d 9.72 (s, 1H,
2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO), 7.71 and 7.34 (d,
JZ4.8 Hz, 4H, 2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO),
6.74 (m, 3H, 2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO),
3.74 (s, 3H, 2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO), 3.04
(s, 6H, 2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO). 13C NMR
(75.47 MHz, CDCl3) d 189.2 (2-C6H4(p-OCH3)C6H3(p-
(CH3)2N)CHO), 110.3, 111.7, 113.6, 114.7, 124.4, 126.6,
130.9, 131.2, 153.2 and 157.6 (2-C6H4(p-OCH3)C6H3(p-
(CH3)2N)CHO), 39.1 (2-C6H4(p-OCH3)C6H3(p-(CH3)2N)
CHO), 54.4 (2-C6H4(p-OCH3)C6H3(p-(CH3)2N)CHO).
Anal. Calcd for C16H17NO2: C, 75.27; H, 6.71; N, 5.49.
Found: C, 75.25; H, 6.68; N, 5.50.
4.4.6. 2-(p-Acetylphenyl)-4-tert-butylbenzaldehyde. Col-
1
ourless oil, n(C]O)Z1708 cmK1. H NMR (300.13 MHz,
CDCl3) d 9.88 (s, 1H, 2-C6H4(p-COCH3)C6H3(p-C(CH3)3)
CHO), 7.74 and 7.46 (d, JZ2.4 Hz, 4H, 2-C6H4(p-COCH3)
C6H3(p-C(CH3)3)CHO), 7.29 (m, 3H, 2-C6H4(p-COCH3)
C6H3(p-C(CH3)3)CHO), 2.48 (s, 3H, 2-C6H4(p-COCH3)
C6H3(p-C(CH3)3)CHO), 1.21 (s, 9H, 2-C6H4(p-COCH3)
C6H3(p-C(CH3)3)CHO). 13C NMR (75.47 MHz, CDCl3) d
190.3 (2-C6H4(p-COCH3)C6H3(p-C(CH3)3)CHO), 108.7,
123.5, 126.9, 127.4, 128.2, 129.4, 131.7, 133.8, 137.2 and
154.7 (2-C6H4(p-COCH3)C6H3(p-C(CH3)3)CHO), 193.7 (2-
C6H4(p-COCH3)C6H3(p-C(CH3)3)CHO), 33.7 (2-C6H4(p-
COCH3)C6H3(p-C(CH3)3)CHO), 30.8 (2-C6H4(p-COCH3)
C6H3(p-C(CH3)3)CHO), 24.8 (2-C6H4(p-COCH3)C6H3(p-
C(CH3)3)CHO). Anal. Calcd for C19H20O2: C, 81.40; H,
7.19. Found: C, 81.36; H, 7.20.
4.4.10. 2,6-Bis(p-methoxyphenyl)-4-methoxybenzalde-
hyde. Colourless solid. Mp 91–92 8C, n(C]O)Z1697 cmK1
.
1H NMR (300.13 MHz, CDCl3) d 9.87 (s, 1H, 2,6-C6H4(p-
OCH3)C6H2(p-OCH3)CHO), 7.34and6.75(d, JZ2.4 Hz, 8H,
2,6-C6H4(p-OCH3)C6H2(p-OCH3)CHO), 7.83 (s, 2H, 2,6-
C6H4(p-OCH3)C6H2(p-OCH3)CHO), 3.75 (s, 3H, 2,6-
C6H4(p-OCH3)C6H2(p-OCH3)CHO), 3.86 (s, 6H, 2,6-
C6H4(p-OCH3)C6H2(p-OCH3)3CHO). 13C NMR (75.47 MHz,
CDCl3) d 189.7 (2,6-C6H4(p-OCH3)C6H2(p-OCH3)CHO),
113.3, 114.7, 126.6, 128.9, 130.9, 131.2, 157.7 and 163.6 (2,
6-C6H4(p-OCH3)C6H2(p-OCH3)CHO), 54.3 (2,6-C6H4(p-
OCH3)C6H2(p-OCH3)CHO), 54.5 (2,6-C6H4(p-OCH3)
C6H2(p-OCH3)CHO). Anal. Calcd for C22H20O4: C,
75.84; H, 5.79. Found: C, 75.86; H, 5.82.
4.4.7. 2-(p-Methoxyphenyl)-4-tert-butylbenzaldehyde.
Pale yellow needles. Mp 74–75 8C, n(C]O)Z1722 cmK1
.
1H NMR (300.13 MHz, CDCl3) d 9.98 (s, 1H, 2-C6H4(p-
OCH3)C6H3(p-C(CH3)3)CHO), 7.82 and 7.55 (d, JZ
8.8 Hz, 4H, 2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO), 7.11
(m, 3H, 2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO), 3.77 (s,
3H, 2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO), 1.36 (s, 9H,
2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO). 13C NMR
(75.47 MHz, CDCl3) d 191.0 (2-C6H4(p-OCH3)C6H3(p-
C(CH3)3)CHO), 114.2, 124.4, 124.9, 125.5, 128.3, 128.7,
129.1, 130.4, 133.1 and 157.4 (2-C6H4(p-OCH3)C6H3(p-
C(CH3)3)CHO), 34.3 (2-C6H4(p-OCH3)C6H3(p-C(CH3)3)
CHO), 30.1 (2-C6H4(p-OCH3)C6H3(p-C(CH3)3)CHO),
4.4.11. 2,6-Bis(p-methoxyphenyl)-4-dimethylaminoben-
zaldehyde. Pale yellow solid. Mp 108–109 8C, n(C]O)
Z
1
1708 cmK1. H NMR (300.13 MHz, CDCl3) d 9.75 (s, 1H,
2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)CHO), 7.37 and 6.76
(d, JZ2.4 Hz, 8H, 2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)
CHO), 7.63 (s, 2H, 2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)
CHO), 3.77 (s, 6H, 2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)
CHO), 3.08 (s, 6H, 2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)
CHO). 13C NMR (75.47 MHz, CDCl3) d 190.2 (2,6-C6H4(p-
OCH3)C6H2(p-(CH3)2N)CHO), 112.7, 114.8, 125.9, 126.4,
128.7, 130.9, 132.5 and 157.6 (2,6-C6H4(p-OCH3)C6H2

¨
I. Ozdemir et al. / Tetrahedron 61 (2005) 9791–9798
9798
G. J. P.; Gibson, V. C.; White, A. J. P.; Williams, D. J.; White,
A. H.; Skelton, B. W. J. Organomet. Chem. 2001, 617–618,
546.
(p-(CH3)2N)CHO), 39.3 (2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)
CHO), 54.7 (2,6-C6H4(p-OCH3)C6H2(p-(CH3)2N)CHO).
Anal. Calcd for C23H23NO3: C, 76.43; H, 6.41; N, 3.88.
Found: C, 76.45; H, 6.43; N, 3.84.
6. Crudden, C. M.; Allen, D. P. Coord. Chem. Rev. 2004, 248,
2247.
4.4.12. 2,6-Bis(p-methoxyphenyl)-4-tert-butylbenzalde-
7. Herrmann, W. A. Angew. Chem., Int. Ed. 2002, 41, 1290.
8. Perry, M. C.; Burgess, K. Tetrahedron: Asymmetry 2003, 14,
951.
hyde. Colourless solid. Mp 86–87 8C, n(C]O)Z1702 cmK1
.
1H NMR (300.13 MHz, CDCl3) d 9.98 (s, 1H, 2,6-C6H4(p-
OCH3)C6H2(p-C(CH3)3)CHO), 7.38 and 6.77 (d, JZ
2.4 Hz, 8H, 2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO),
7.54 (s, 2H, 2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO),
3.84 (s, 6H, 2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO),
1.36 (s, 9H, 2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO).
13C NMR (75.47 MHz, CDCl3) d 192.3 (2,6-C6H4(p-
OCH3)C6H2(p-C(CH3)3)CHO), 113.1, 115.9, 125.7, 126.2,
129.9, 130.3, 132.4 and 158.9 (2,6-C6H4(p-OCH3)C6H2(p-
C(CH3)3)CHO), 35.5 (2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)
CHO), 31.3 (2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO),
55.6 (2,6-C6H4(p-OCH3)C6H2(p-C(CH3)3)CHO). Anal.
Calcd for C25H26O3: C, 80.18; H, 7.00. Found: C, 80.20;
H, 6.97.
9. Peris, E.; Crabtree, R. H. Coord. Chem. Rev. 2004, 248, 2239.
10. Zapf, A.; Beller, M. Chem. Commun. 2005, 431.
11. Bedford, R. B.; Cazin, C. S. J.; Holder, D. Coord. Chem. Rev.
2004, 248, 2283.
12. Lee, H. M.; Lu, C. Y.; Chen, C. Y.; Chen, W. L.; Lin, H. C.;
Chiu, P. L.; Cheng, P. Y. Tetrahedron 2004, 60, 5807.
13. Wang, A.-E.; Xie, J.-H.; Wang, L.-X.; Zhou, Q.-L. Tetra-
hedron 2005, 61, 259.
14. Christmann, U.; Vilar, R. Angew. Chem., Int. Ed. 2005, 44,
366.
¨
15. Herrmann, W. A.; Ofele, K.; Preysing, D.; Herdtweck, E.
J. Organomet. Chem. 2003, 684, 235.
¨
16. (a) Gu¨rbu¨z, N.; Ozdemir, I.; Demir, S.; C¸ etinkaya, B. J. Mol.
¨
Catal. A 2004, 209, 23. (b) Ozdemir, I.; C¸ etinkaya, B.; Demir,
¨
S.; Gu¨rbu¨z, N. Catal. Lett. 2004, 97, 37. (c) Ozdemir, I.;
Demir, S.; Yas¸ar, S.; C¸ etinkaya, B. Appl. Organomet. Chem.
4.4.13. 2,5-Bis(p-methoxyphenyl)terephtalaldehyde. Col-
ourless solid. Mp 121–122 8C, n(C]O)Z1716 cmK1 1H
.
NMR (300.13 MHz, CDCl3) d 10.12 (s, 2H, 2,5-C6H4(p-
OCH3)C6H2(CHO)2), 7.42 and 6.90 (d, JZ8 Hz, 4H, 2,5-
C6H4(p-OCH3)C6H2(CHO)2), 7.35 and 6.75 (d, JZ1.2 Hz,
4H, 2,5-C6H4(p-OCH3)C6H2(CHO)2), 7.98 (s, 2H, 2,5-
C6H4(p-OCH3)C6H2(CHO)2), 3.79 (s, 6H, 2,5-C6H4(p-
OCH3)C6H2(CHO)2). 13C NMR (75.47 MHz, CDCl3) d
189.5 (2,5-C6H4(p-OCH3)C6H2(CHO)2), 95.1, 113.0, 114.6,
126.6, 128.9, 131.1 and 157.6 (2,5-C6H4(p-OCH3)
C6H2(CHO)2), 54.1 (2,5-C6H4(p-OCH3)C6H2(CHO)2).
Anal. Calcd for C22H18O4: C, 76.29; H, 5.24. Found: C,
76.32; H, 5.26.
¨
2005, 19, 55. (d) Gu¨rbu¨z, N.; Ozdemir, I.; Sec¸kin, T.;
C¸ etinkaya, B. J. Inorg. Organomet. Polym. 2004, 14, 149.
¨
17. (a) Ozdemir, I.; Gok, Y.; Gurbuz, N.; Yas¸ar, S.; C¸ etinkaya, E.;
¨
¨
¨
¨
C¸ etinkaya, B. Pol. J. Chem. 2004, 78, 2141. (b) Ozdemir, I.;
¨
¨
Gok, Y.; Gurbuz, N.; C¸ etinkaya, E.; C¸ etinkaya, B. Synth.
¨
¨
Commun. 2004, 34, 4135. (c) Ozdemir, I.; Gok, Y.; Gurbuz,
¨
¨
¨
N.; C¸ etinkaya, E.; C¸ etinkaya, B. Heteroat. Chem. 2004, 15,
¨
419. (d) Ozdemir, I.; Alıcı, B.; Gu¨rbu¨z, N.; C¸ etinkaya, E.;
C¸ etinkaya, B. J. Mol. Catal. A 2004, 217, 37.
18. Alıcı, B.; Cetinkaya, E.; Cetinkaya, B. Heterocycles 1997, 45,
29.
19. (a) Mayr, M.; Wurst, K.; Ongania, K.-H.; Buchmeiser, M. R.
Chem. Eur. J. 2004, 10, 1256. (b) Mayr, M.; Buchmeiser,
M. R. Macromol. Rapid Commun. 2004, 25, 231.
Acknowledgements
¨
20. Herrmann, W. A.; Schneider, S. K.; Ofele, K.; Sakamoto, M.;
We thank the Technological and Scientific Research
¨ ˙
Council of Tu¨rkiye TUBITAK [TUBITAK COST D17
¨
Herdtweck, E. J. Organomet. Chem. 2004, 689, 2441.
21. Farina, V. Adv. Synth. Catal. 2004, 346, 1553.
22. Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 2002, 41, 4176.
23. Loch, J. A.; Albrecht, M.; Peris, E.; Mata, J.; Faller, J. W.;
Crabtree, R. H. Organometallics 2002, 21, 700.
24. Ballie, C.; Xiao, J. Tetrahedron 2004, 60, 4159.
25. Zhang, C.; Huang, J.; Trudell, M. L.; Nolan, S. P. J. Org.
Chem. 1999, 64, 3804.
¨ ¨
and TBAG-2474 (104T085)] and Inonu University
Research Fund (I.U.B.A.P. 2005/42) for financial support
˙ ¨
of this work.
References and notes
26. Grasa, G. A.; Viciu, M. S.; Huang, J.; Zhang, C.; Trudell,
M. L.; Nolan, S. P. Organometallics 2002, 21, 2866.
27. Hillier, A. C.; Grasa, G. A.; Mihai, S.; Viciu, M. S.; Lee,
H. M.; Yang, C.; Nolan, S. P. J. Organomet. Chem. 2002, 653,
69.
¨
1. Herrmann, W. A.; Kocher, C. Angew. Chem., Int. Ed. 1997, 36,
2163.
2. Weskamp, T.; Bohm, V. P. W.; Herrmann, W. A.
J. Organomet. Chem. 2000, 600, 12.
¨
28. Altenhoff, G.; Goddard, R.; Lehmann, C. W.; Glorius, F.
J. Am. Chem. Soc. 2004, 126, 15195.
¨
29. Ozdemir, I.; Gu¨rbu¨z, N.; C¸ etinkaya, B. Tetrahedron Lett.
3. Herrmann, W. A. Adv. Organomet. Chem. 2002, 48, 1.
4. Bourissou, D.; Guerret, O.; Gabbai, F. P.; Bertrand, G. Chem.
Rev. 2000, 100, 39.
2005, 46, 2273.
5. Magill, A. M.; McGuiness, D. S.; Cavell, K. J.; Britovsek,