Bis(pyrimidine)-based palladium catalysts: Synthesis, X-ray structure and applications in Heck-, Suzuki-, Sonogashira-Hagihara couplings and amination reactions

Article abstract of DOI:10.1016/S0022-328X(01)01083-X

The synthesis of N,N-bis(pyrimid-2-yl)amine (1), N-acetyl-N,N-bis(pyrimid-2-yl)amide (2), N-norborn-2-ene-5-ylbis(pyrimid-2-yl)carbamide (4) is described. The Pd-complex N-acetyl-N,N-bis(pyrimid-2-yl)amine palladium dichloride (3) has been prepared from compound 2 and its X-ray structure has been determined. A polymer supported catalytic system (6) was prepared via ring-opening metathesis copolymerization of 4 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene (HDMN-6) and subsequent loading with PdCl₂. Both the homogeneous and heterogeneous catalysts 3 and 6 were active in Heck-, Suzuki-, Sonogashira-Hagihara-type couplings and amination reactions using aryl iodides, bromides and chlorides.

Full text of DOI:10.1016/S0022-328X(01)01083-X

Journal of Organometallic Chemistry 634 (2001) 39–46
www.elsevier.com/locate/jorganchem
Bis(pyrimidine)-based palladium catalysts: synthesis, X-ray
structure and applications in Heck–, Suzuki–,
Sonogashira–Hagihara couplings and amination reactions
Michael R. Buchmeiser a,*, Thomas Schareina b, Rhett Kempe b,*, Klaus Wurst c
a Institut fu¨r Analytische Chemie und Radiochemie, Uni6ersita¨t Innsbruck, Innrain 52 a, A-6020 Innsbruck, Austria
b Institut fu¨r Organische Katalyseforschung an der Uni6ersita¨t Rostock e.V., Buchbinderstraße 5-6, D-18055 Rostock, Germany
c Institut fu¨r Allgemeine, Anorganische und Theoretische Chemie Uni6ersita¨t Innsbruck, Innrain 52 a, A-6020 Innsbruck, Austria
Received 18 April 2001; accepted 10 June 2001
Abstract
The synthesis of N,N-bis(pyrimid-2-yl)amine (1), N-acetyl-N,N-bis(pyrimid-2-yl)amide (2), N-norborn-2-ene-5-ylbis(pyrimid-2-
yl)carbamide (4) is described. The Pd-complex N-acetyl-N,N-bis(pyrimid-2-yl)amine palladium dichloride (3) has been prepared
from compound 2 and its X-ray structure has been determined. A polymer supported catalytic system (6) was prepared via
ring-opening metathesis copolymerization of 4 with 1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanonaphthalene (HDMN-6)
and subsequent loading with PdCl2. Both the homogeneous and heterogeneous catalysts 3 and 6 were active in Heck–, Suzuki–,
Sonogashira–Hagihara-type couplings and amination reactions using aryl iodides, bromides and chlorides. © 2001 Elsevier
Science B.V. All rights reserved.
Keywords: Aminations reactions; Palladium catalysts; Coupling; ROMP; Heterogeneous catalysis
actions of the methyl groups with either the palladium
chloride or the carbonyl moiety, we moved to similar
electron-rich, yet unsubstituted systems. In this contri-
bution, we report on the synthesis, the properties and
use of monomeric and polymer-supported bis(pyrim-
idyl)-based palladium complexes.
1. Introduction
Palladium-mediated reactions including polymeriza-
tions, CꢀC coupling reactions, aminations and hy-
drophosphorylations have attracted significant interest
during the last years [1–8]. In course of our search for
non-phosphorous-based ligands, we already reported
on the use of bidentate N,N-based analogues. So far,
these systems have been based on (substituted) N,N-
dipyridylcarbamides [9,10]. They are completely air-sta-
ble, show high activities in various coupling reactions of
aryl iodides and bromides and may—with some restric-
tions—also be used for CꢀC coupling reactions of aryl
chlorides [11]. In order to obtain even more stable and
active systems we already investigated homologous
methyl-substituted and benzo-anelated derivatives [11].
Since these systems generally suffered from steric inter-
2. Results and discussion
2.1. Synthesis of bis(pyrimid-2-yl)amine (1)
Palladium catalyzed aryl-X activation (X=I, Br or
Cl) reactions are an efficient tool for the synthesis of bi-
and triaryl amines via CꢀN-bond formation [12,13]. In
analogy to 2-X-pyridines [11], 2-X-pyrimidine was used.
X can be Cl since the systems are activated, but the
formation of catalyst deactivating palladium pyrimidine
complexes has to be avoided. In order to prevent this,
the palladium catalyst has to be stabilized by chelating
bisphosphine ligands [12]. Reaction of 2-aminopyrim-
idine with one equivalent of 2-chloropyrimidine and
* Corresponding authors. Tel.: +43-512-5075184; fax: +43-512-
507-2677 (M.R.B.); Tel.: +43-381-4669369; fax: +43-381-4669369
(R.K.).
E-mail addresses: michael.r.buchmeiser@uibk.ac.at (M.R. Buch-
meiser), rhett.kempe@ifok.uni-rostock.de (R. Kempe).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01083-X

40
M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
Scheme 1. Synthesis of compounds 1–4.
1.15 equivalents of sodium-tert-butylate in the presence
of 0.65 mol% bis-diphenylphosphinopropane and 0.32
mol% Pd2dba3 in toluene at 80 °C yields 1 overnight.
Workup is a bit tedious because of the low solubility of
the bis(pyrimid-2-yl)amine in standard solvents, but by
extraction and recrystallization from water, followed by
drying, the product was obtained in reasonable yields.
sis of the support, the polymerization of 4 was initiated
by Mo(N-2,6-i-Pr2)(CHCMe2Ph)(OCMe(CF3)2)2. Sub-
sequent cross-linking with 1,4,4a,5,8,8a-hexahydro-
1,4,5,8-exo-endo-dimethanonaphthalene
(DMN-H6)
results in the formation of the ligand containing sup-
port (Scheme 2). The entire setup results in the forma-
tion of irregularly shaped particles with an average size
of 20–40 mm. This size guarantees the convenient re-
moval of the catalyst at the end of the reaction by
means of filtration. Due to the living character of the
polymerization, a quantitative incorporation of 4 into
the subsequently formed support is guaranteed. As
already described earlier for similar systems [14], this
allows the synthesis of tailor-made supports in terms of
catalyst loading simply by stoichiometry of the reac-
tants. The reaction sequence itself results in the forma-
tion of a highly cross-linked matrix with the linear,
ligand carrying polymer chains attached to its surface.
2.2. Synthesis of monomeric palladium complex 3
Compound 2 was prepared according to a previously
published procedure [11] from 1 and acetyl chloride.
The synthesis of the palladium (II) complex 3 was
accomplished by reaction of a methanolic solution of
compound 2 with an aqueous solution of H2PdCl4,
freshly prepared from PdCl2 and HCl (Scheme 1). The
resulting palladium compound is only soluble in highly
polar organic solvents such as DMSO or DMF. In
order to obtain information on structural features of
this compound, complex 3 was characterized by X-ray
analysis. Complex 3 crystallizes in the monoclinic space
group P21/c and shows the expected almost perfect
square planar conformation around the palladium cen-
ter (Fig. 1). The angle formed by the two pyrimidines
was found to be 56.1(1)°, thus being similar to the one
found in the related dipyrid-2-yl-analogue (54.8(1)°)
[10]. Analogous similarities are found in the angle
defined by C2ꢀN1ꢀC2% (117.3(2) vs. 116.5(3)°). A de-
tailed summary of the relevant structural data is given
in Tables 1 and 2.
2.3. Synthesis of polymer supported Pd-catalysts and
their use in coupling reactions
2.3.1. Synthesis of support
Compound 4 was prepared in an analogous way as
described for compound 2 (Scheme 1). For the synthe-
Fig. 1. Structure of compound 3.

M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
41
Table 1
Selected X-ray data for 3
ligand-containing polymer chains. This extensive sorp-
tion capacity for Pd leads to the favorable situation,
were comparably high Pd loadings may be achieved
with a comparably low amount of ligand. Despite the
two different binding sites in this support, no leaching
of Pd was observed during any type of coupling reac-
tion. In all cases, the reduced (presumably Pd(0)) spe-
cies remains virtually quantitatively attached to the
support at the end of the reaction.
3
Molecular formula
Formula weight
Temperature (K)
Crystal system
Space group
C
392.52
223(2)
Monoclinic
P21/c
1208.71
1423.69
744.49
90
90.158(2)
90
1.28113(7)
4
2.035
1.863
10H9C12N5OPd
,
a (A)
,
b (A)
,
c (A)
2.3.2. Heck couplings (entries 1–9, Table 3)
h (°)
i (°)
Heck couplings were carried out with compounds 3
and 6 between aryl iodides, bromides as well as chlo-
rides and styrene and ethyl acrylate, respectively. A
summary of the results is given in Table 3. All three
systems were found to be highly active in the vinylation
of aryl iodides and bromides. Generally speaking reac-
tions carried out in DMAc using NBu3 as this base
turned out to be the best system for this type of
couplings, resulting in almost quantitative yields (91–
96%) and high TONs (up to 11 000). As for the parent
dipyridylamide-based catalyst [10], no significant differ-
ences between the homogeneous system 3 and the het-
erogeneous analogue 6 were observed. Therefore, we
carried out all further coupling reactions with the het-
erogeneous catalyst 6.
Tetrabutylammonium bromide (TBAB) is known to
promote Pd-mediated couplings [15] and may addition-
ally be used as a non-aqueous ionic solvent [16–18].
Consequently, its influence on the reactivity was investi-
gated. In contrast to aryliodides, the successful coupling
of arylchlorides requires the presence of a stabilizing
ligand. Thus, such couplings may be used as a probe
for the effectiveness of a coupling system. Chloroben-
zene does not react under standard conditions. Never-
theless, as observed for dipyridylamide-based systems,
coupling of activated chloroarenes may successfully be
accomplished in the presence of TBAB. While these
coupling results are quite similar to those obtained
previously with dipyridyl-based ligands [10], one differ-
ence was found in the reactions kinetics. Thus, pyrim-
idyl-based ligands exceed the dipyridylamide-based
analogues in terms of turn-over frequency. A compari-
son of these two systems is shown in Fig. 3. As may be
deduced therefrom, coupling reactions between bro-
mobenzene and styrene catalyzed by 6 proceed at about
the same rate as the reaction between the even more
reactive iodobenzene and styrene catalyzed by the par-
ent dipyridylamide system. Obviously, the enhanced
electron density in pyrimidyl-based systems accelerates
these reactions. This strongly indicates that the concept
of electron rich N-based ligands, which should mimic
the phosphine analogues in terms of basicity and elec-
tron density, gives access to more reactive coupling
systems. Such systems are superior to alkyl-substituted
k (°)
V (nm3)
Z
Dcalc (mg m−3
)
Absorption coefficient (mm−1
Color, habit
)
Yellow prism
2035
1.068
R1=0.022,
wR2=0.051
Reflections with I\2|(I)
Goodness-of-fit on F2
R indices [I\2|(I)])
Table 2
,
Selected bond lengths (A) and angles (°) for 3
Bond lengths
Pd(1)ꢀN(2)
Pd(1)ꢀN(4)
Pd(1)ꢀCl(1)
Pd(1)ꢀCl(2)
203.1(2)
204.8(2)
227.76(7)
228.17(7)
Bond angles
N(2)ꢀPd(1)ꢀN(4)
N(2)ꢀPd(1)ꢀCl(1)
N(4)ꢀPd(1)ꢀCl(1)
N(2)ꢀPd(1)ꢀCl(2)
N(4)ꢀPd(1)ꢀCl(2)
Cl(1)ꢀPd(1)ꢀCl(2)
C(3)ꢀN(2)ꢀPd(1)
C(4)ꢀN(2)ꢀPd(1)
C(7)ꢀN(4)ꢀPd(1)
C(8)ꢀN(4)ꢀPd(1)
87.13(8)
91.13(6)
176.24(6)
174.30(6)
91.65(6)
90.40(3)
121.5(2)
121.0(2)
120.7(2)
122.3(2)
Subsequent reaction of this support with H2PdCl4 gives
the desired heterogeneous Pd catalysts. One significant
difference to the parent dipyridylamide-based system
needs to be addressed. Thus, the Pd-content of the
Pd-loaded support as determined by ICP-OES was
found to be roughly twice as much as the bis(pyrim-
idine) content of the unloaded support as determined
by elemental analysis would let expect. Apparently,
complexation of the Pd-units does not only occur as
observed in 3 but also between the repetitive units and
polymer chains, respectively, as illustrated in Fig. 2.
The deep orange color of the supports as well as a
comparably reduced softness of the support further
indicate some cross-linking between the surface bound,

42
M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
Scheme 2. Synthesis of resin 6.
dipyrid-2-ylamines, since these suffer from unfavorable
steric interactions between the alkyl groups and the
carbonyl and chlorine moieties, respectively, thus re-
sulting in distorted and consequently unstable catalysts
[11].
2.3.5. Sonogashira–Hagihara couplings (entries 21–25,
Table 5)
The heterogeneous system 6 is highly active in alkyne
coupling reactions, in particular if aryl iodides are used.
Virtually quantitative yields are obtained without the
presence of additional Cu (I). The use of the less active
aryl bromides results in satisfactory yields of up to 85%
even with Pd amounts as low as 0.006 mol%. Again, the
reaction of aryl chlorides may be accelerated effectively
by TBAB to give yields similar to those obtained with
aryl bromides. Unfortunately, we were not able to
perform any alkyne couplings with N-containing sub-
2.3.3. Suzuki-couplings (entries 10–14, Table 4)
Suzuki couplings [4,19–21] represent an interesting
yet still comparably expensive alternative to Heck cou-
plings. With the present system (6), reaction of aryl
boronic acids with iodoarenes in THF proceeds
smoothly with yields \80%. Coupling reactions with
bromoarenes require comparably high amounts of Pd
(up to 0.2 mol%) in order to obtain acceptable yields.
Chloroarenes basically do not react under standard
conditions (refluxing THF), yields are less than 5%. In
light of recent results published on the Suzuki coupling
of even deactivated aryl chlorides [22], the use of the
present system for this type of CꢀC coupling reaction
definitely appears less attractive.
strates,
e.g.
between
iodobenzene
and
2-
ethynylpyridine.
3. Experimental
3.1. Instrumentation
NMR data were obtained in the indicated solvent at
25 °C on a Bruker Spectrospin 300 and on a Bruker
AM400, respectively, and are listed in parts per million
downfield from tetramethylsilane for proton and car-
bon. Coupling constants are listed in Hertz. IR spectra
were recorded on a Nicolet 510 FT-IR. Titrations were
performed using a 686 Titroprocessor (Metrohm,
Switzerland). Eluents were degassed with He 5.0. Ele-
2.3.4. Aminations and h-arylations (entries 15–20
Table 4) [23]
The combination of strong, sterically non-hindered
bases and activated alkenes such as ethyl acrylate al-
lows to run a-aminations in comparably high yields (up
to 90%). Weaker bases such as ammonia result in the
formation of the corresponding mono and dialkylated
species in acceptable yields (60%). Interestingly, even
non-activated chloroarenes may be converted into the
corresponding N-aryl derivatives with comparably high
TONs (up to 4400) and yields (up to 80%). Addition-
ally, no transcomplexation is observed even with
strong amines, thus underlining the high stability of the
bispyrimidyl complexes. Finally, the catalytic system
also provides access to a-arylations, yet yields are too
low (B45%) to be of any significant synthetic value.
Fig. 2. ‘Fully’ Pd-loaded support 6.

M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
43
Table 3
Summary of Heck-type couplings
a
c
ArꢀX
H2CꢁCHR
Product
Catalyst
Yield (%)
TON×103
1
2
3
4
5
6
7
8
9
9
Bromobenzene
4-Bromobenzonitrile
Styrene
Styrene
Styrene
Ethylacrylate
Ethylacrylate
Styrene
Styrene
Styrene
Stilbene
3
6
3
3
3
3
3
3
6
3
96
98
98
98
65
0
30
0
70
63
8.6
2.3a
7.3
7.3
6.6
0
1.0
0
10.8
4.2
4-Cyanostilbene
4-Fluorostilbene
4-Fluorocinnamate
4-Methoxycinnamate
Stilbene
4-Bromo-1-fluorobenzene
4-Bromo-1-fluorobenzene
4-Methoxybromobenzene
Chlorobenzene
Chlorobenzene/TBAB
4-Chloroacetophenone
4-Chloroacetophenone/TBAB
4-Chloroacetophenone/TBAB
Stilbene
4-Acetylstilbene
4-Acetylstilbene
4-Acetyistilbene
Styrene
Styrene
Reactions were carried out in DMAc/N-Bu3N at T=150 °C. TBAB, tetrabutylammonium bromide.
a Isolated yields. The amount of Pd added was in the range of 0.006–0.03 mol%.
mental analyses were carried out at the Institute of
Physical Chemistry, University of Vienna. Further in-
strumentation for ICP-OES experiments and for the
determination of the specific surface area (|) by means
of GPC, is described elsewhere [9].
in vacuum for a short time. The raw material is contin-
uously extracted with boiling water (e.g. in a soxhlet)
for some hours; most of the material dissolves, until
only black or brown solids remain. Upon cooling,
colorless to yellow needles precipitate from the extrac-
tion solution. Recrystallization from water can be re-
peated. These crystals contain 2 mol of water, which
can be removed by drying in a vacuum desiccator over
KOH for 24 h. Yield: 1.34 g (39% of theory) of fine,
colorless needles.1H (dmso-d6,): l 10.03 (s, 1H, NH);
3.2. Reagents and standards
Synthesis of the ligands and polymerizations were
performed under an argon atmosphere by standard
Schlenk techniques or in an Ar-mediated dry-box
(Braun, Germany) unless stated otherwise. Reagent
grade diethyl ether, pentane, tetrahydrofurane and tolu-
ene were distilled from sodium benzophenone ketyl
under argon. Reagent grade dichloromethane, 1,2-di-
chioroethane were distilled from CaH under argon.
Other solvents and reagents were used as purchased.
N,N-Dimethylformamide (DMF) was dried over
molecular sieves. Deionized water was used throughout.
endo-Norborn-2-ene-5-carboxylic acid chloride [9],
1,4,4a,5,8,8a-hexahydro-1,4,5,8-exo-endo-dimethanon-
aphthalene (DMN-H6), the initiators, Mo(N-2,6-(i-Pr2-
C6H3)(CHCMe2Ph)(OCMe(CF3)2)2) [24], were prepared
according to literature procedures and checked for pu-
rity by means of NMR.
8.57 (d, 4H, Hmeta); 7.03 (t, 2H, Hpara)
13C (dmso-d6): l
159.2; 158.4; 115.4. Elemental Anal. Calc. for C8H7N5
(Mw=173.17 g mol−1): C, 55.48; H, 4.07; N, 40.44.
Found: C, 55.79; H, 4.01; N, 40.53%.
3.4. N-Acetyl-bis(pyrimid-2-yl)amide (2)
Compound 1 (250 mg, 1.4 mmol) was dissolved in a
mixture of 0.15 ml of acetic anhydride and 0.15 ml of
acetylchloride. The reaction mixture was refluxed for 12
h. The volatiles were removed in vacuo and 2 was
3.3. Bis(pyrimid-2-yl)amine (1)
2-Aminopyrimidine (1.90 g, 20 mmol) ), 2.29 g (20
mmol) 2-chloropyrimidine, 54 mg (1.3×10−4 mol) bis-
diphenylphoshinopropane, 60 mg (6.5×10−4 mol)
dipalladium-trisbenzylideneacetone, 2.23 g (23.2 mmol)
sodium-tert-butylate and 20 ml toluene are combined in
a Schlenk vessel under Argon. The mixture, which
colorizes yellow and warms already while mixing the
compounds, is kept at 80 °C for 16 h. After cooling, 20
ml water are added and a yellowish solid is collected by
filtration over a sintered glass filter. The solid is washed
twice with toluene and once with n-pentane, then dried
Fig. 3. Comparison of reaction rates (expressed in turn overs). (A)
Bis(pyrimidyl)-catalyzed Heck reaction of styrene with C6H5Br; (B)
parent dipyridylamide-catalyzed Heck reaction of styrene with C6H5I.

44
M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
Table 4
Summary of Suzuki couplings, aminations and a-arylations
a
c
ArꢀX
Product
Catalyst Yield (%)
TON×103
ArꢀB(OH)2, Arꢁ
10 4-MeC6H4-
11 4-MeOC6H4-
12 4-MeC6H4-
13 4-MeOC6H4-
14 4-MeC6H4-
Iodobenzene
Bromobenzene
Bromobenzene
4-Bromoanisole 4,4%-Bis(methoxy)biphenyl
Chlorobenzene
4-Methylbiphenyl
4-Methoxybiphenyl
4-Methylybiphenyl
6
6
6
6
6
83
35
74
32
B5
6.5
2.9
0.7
2.6
0.46
4-Methylybiphenyl
Amine
15 Piperidine
16 Piperidine
17 Diethylamine
18 Ammonia (30%) Ethylacrylate
19 Morpholine
Chlorobenzene
Chiorobenzene
Ethylacrylate
N-Phenylpipendine b
6
6
6
6
6
24
80
79
4.4
1.4
10
7
11.5
N-Phenylpipefldine b
b-(N,N-Diethylamino)-ethylpropionate
(b-Amino)E/N,N-bis-(1-ethoxy-carbonyleth-2-yl)amine
b-(N-Morpholino)ethylpropionate
60 (1:2 mixture)
90
Ethylacrylate
CH-acidic compound
20 CH2(CO2Et)2
Bromobenzene
PhCH(CO2Et)2
6
43
13.4
Reactions were carried out in THF at T=65 °C, reaction time=6 h. T=NBu+4 Br−
a Isolated yields.
b Reaction was carried out in dioxane at 100 °C. The amount of Pd added was 0.005–0.2 mol-%, base=Cs2CO.
.
Table 5
Summary of Sonogashira–Hagihara couplings
a
c
RꢀCCH
ArꢀX
Product
Catalyst
Yield
TON×103
21
22
23
24
25
PhꢀCCH
PhꢀCCH
PhꢀCCH/TBAB
Tris(2-propyl)silylethyne
Tris(2-propyl)silylethyne
Iodobenzene
Diphenylacetylene
Diphenylacetylene
Diphenylacetylene
Diethynylbenzene
Diethynylbenzene
6
6
6
6
6
98
68
65
85
50
22.3
15.5
14.8
12.4
7.3
Bromobenzene
Chlorobenzene
Dibromobenzene
Dichlorobenzene
Reactions were carried out in THF at T=65 °C. Reaction time=72 h. The amount of Pd added was in the range of 0.007–0.004 mol%,
base=Bu3N.
a Isolated yields.
purified by column chromatography (silica G 60, 220–
400 mesh, THF). Yield: 217 mg (70%). IR (KBr): 1705
(CꢁO), 1686, 1563 (Ar), 1391, 1374 (CH3), 1310, 1038,
(CO), 161.3, 158.8, 121.8, 118.9, 25.3 (CH3). For X-ray
data refer to Tables 1 and 2.
1
3.6. N,N,-Bis(pyrimid-2-yl) (4)
814, 697, 608, 594. H-NMR (dmso-d6) l 8.58 (d, 4H,
J=3.0), 7.14 (t, 2H, J=3.0), 2.52 (s, 3H). 13C-NMR
(dmso-d6) l 172.3 (CꢁO), 160.5 (Cipso), 158.6, 118.4,
25.8 (CH3).
Norborn-2-ene-5-ylcarboxylic chloride 0.5 ml, 3.2
mmol) was added to a solution of 1 (0.25 g, 1.4 mmol)
in dichloroethane (4 ml). The reaction mixture was
refluxed for 24 h and poured on saturated aq. NaHCO3
solution. Extraction was performed with methylene
chloride. The combined organic layers were dried over
sodium sulfate. After evaporation of the solvent, the
residue was recrystallized from diethyl ether. Yield: 250
3.5. N-Acetyl-bis(pyrimid-2-yl)-
aminopalladium(II)dichloride (3)
Compound 2 (50 mg, 0.23 mmol) was dissolved in
methanol and an aq. solution of H2PdCl4 (prepared
from 50 mg PdCl2 and HCl, pH adjusted with NaOH
to approximately 6) was added. The slightly cloudy
solution was allowed to stand overnight, after which
crystals of 3 suitable for X-ray analysis were filtered off.
Yield: 72 mg (80%). IR (KBr): 1733 (CꢁO), 1590 (Ar),
1
mg (61%). H-NMR (dmso-d6) l 8.68 (d, 4H, J=4.9),
713 (t, 2H, J=4.9), 5.30 (m, 2H), 4.00 (m, 1H,
CHCON), 3.01 (bs, 1H, CH), 2.84 (bs, 1H, CH), 1.81
(m, 1H, CH), 1.56 (m, 2H, 2 CH). 13C-NMR (dmso-d6)
l 177 (CO), 161.1, 158.6, 137.3, 132.7, 118.2, 49.5, 46.0,
45.5, 42.8, 30.3. Elemental Anal. Calc. for C16H15N5O
(Mw=293.328 g mol−1) C, 65.52; H, 5.15; N, 23.88.
Found: C, 65.70; H, 5.22; N, 23.52%.
1
1526, 1438, 1300, 1223 (CO), 826, 818, 809, 660. H-
NMR (dmso-d6) l 8.78 (d, 4H, J=4.9), 7.42 (t, 2H,
J=4.9), 2.45 (s, 3H). 13C-NMR (dmso-d6) l 171.5

M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
45
3.7. Preparation of the resin 6
3.11. X-ray measurement and structure determination
of 3
The preparation and characterization of the resin
(40910 mm, 0.19 mmol bis(pyrimidylamide) was per-
formed under an argon atmosphere by standard
Schlenk techniques according to previously published
procedures [9,11]. Loading with palladium (II) was
achieved by stirring the resin in an aq. solution of
H2PdCl4 (1000 mg ml−1 in 5% HCl, pH adjusted to 5.0
with NaOH) at room temperature (r.t.) for 12 h. The
actual amount of palladium (II) sorbed onto the resin
Compound 3 was measured on a Nonius Kappa
CCD area-detector diffractometer with graphite-
,
monochromatized Mo–Ka radiation (u=0.71073 A)
via a mixture of 2° f and v-scans, placing the CCD
detector 36 mm from the crystal. The raw data were
processed with the program DENZO-SMN [25] to obtain
conventional data. The structure was solved by direct
methods (SHELXS-86) [26] and refined by full matrix
least-squares against F2 (SHELXL-93) [27]. The function
minimized was ꢀ[w(FO2 −F2C)2] with the weight defined
as w−1=[|2(F2O)+(xP)2+yP] and P=(FO2 +2F2C)/3.
All non-hydrogen atoms were refined with anisotropic
displacement parameters. Hydrogen atoms were located
by difference Fourier methods, but in the refinement
they were generated geometrically and refined with
isotropic displacement parameters 1.2 and 1.5 (methyl
group) times higher than Ueq of the attached carbon
atoms. Selected crystallographic data are summarized
in Tables 1 and 2.
as determined by ICP-OES was 0.4 mmol g−1
.
3.8. Heck-couplings
The educts (1:1 ratio, 1–2 g) were dissolved in 70–
100 ml of solvent (used as purchased), then the base
(1.2 equivalents) and the catalyst were added. Cou-
plings were carried out at T=140 °C in DMAc. Reac-
tion times were 72 h unless stated otherwise. For
work-up, the reaction mixture was poured on water,
acidified with HCl (2 N) and extracted with diethyl
ether (3–5×50 ml). The combined organic phases were
dried over Na2SO4. Finally, the solvent and (where
applicable) the reactants were evaporated in vacuo. The
coupling products were isolated by flash chromatogra-
phy (silica G-60, 4×30 cm, pentane–diethyl ether=
90:10) and repeated crystallization. Purity of the
4. Summary
N-acyl substituted bispyrimidylamines form stable
Pd complexes which may be used as highly active
catalysts in a large variety of CꢀC and CꢀN coupling
reactions. Similar to the parent N-acyldipyridylamines,
bispyrimidylamines may be incorporated into a poly-
meric matrix via ROMP. The pyrimidyl-based systems
exceed the parent system in terms of reactivity and
additionally allow the extensive Pd-loading of the het-
erogeneous support by virtually quantitative complexa-
tion of all pyrimidine nitrogens.
1
corresponding crops was determined by H-NMR.
3.9. Suzuki-couplings, aminations and h-arylations
The educts (1:1 ratio, 1–2 g) were dissolved in 10–20
ml of THF, the base as well as the catalyst were added.
Reactions were carried out in THF at T=65 °C for 72
h. Cs2CO3 (1.5 equivalents) was used for Suzuki cou-
plings and a-arylations, aminations were carried out in
the absence of a base. For work-up, the reaction mix-
ture was poured on water and the aq. phase was
extracted with diethyl ether. After drying over Na2SO4,
the solvent was evaporated. The corresponding prod-
ucts were purified by crystallization from diethyl ether–
pentane.
5. Supplementary material
Further details are available from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK (Fax: +44-1223-336033; e-mail:
deposit@ccdc.cam.ac.uk or www: http://www.ccdc.cam.
ac.uk) on quoting the depository numbers CCDC-
161925, the names of the authors, and the journal
citations.
3.10. Sonogashira–Hagihara couplings
The educts (1:1 ratio, 1–2 g) were dissolved in 10–20
ml of THF (used as purchased), then the base (tri-n-
butylamine, 1.5 equivalents) and the catalyst were
added. Reactions were carried out at T=65 °C for 72
h. For work-up, the reaction mixture was poured on
water and the aq. phase was extracted with diethyl
ether. After drying over Na2SO4, the solvent was evap-
orated. The corresponding products were purified by
crystallization from diethyl ether/pentane.
Acknowledgements
Financial support provided by the FWF Vienna
(grant number P-12963-GEN) is gratefully acknowl-
edged. R.K. thanks the Deutsche Forschungsgemein-
schaft, the Bundesministerium fu¨r Bildung und
Forschung, the Fonds der Chemischen Industrie, the

46
M.R. Buchmeiser et al. / Journal of Organometallic Chemistry 634 (2001) 39–46
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11101.
[11] J. Silberg, T. Schareina, R. Kempe, K. Wurst, M.R. Buchmeiser,
J. Organomet. Chem. 622 (2000) 6.
[12] S. Wagaw, S.L. Buchwald, J. Org. Chem. 61 (1996) 7240.
[13] J.F. Hartwig, Synlett (1996) 329.
[14] M.R. Buchmeiser, N. Atzl, G.K. Bonn, J. Am. Chem. Soc. 119
(1997) 9166.
Max-Planck-Gesellschaft, the Karl-Winnacker-Stiftung,
the Aventis R&D GmbH, Degussa-Hu¨ls AG, the SKW
Trostberg AG, the Gru¨nenthal GmbH, the SynTec
Wolfen GmbH and Organica Wolfen GmbH for finan-
cial support. Special thanks to N. Rainalter for experi-
mental assistance.
[15] G.T. Crisp, M.G. Gebauer, Tetrahedron 52 (1996) 12465.
[16] W.A. Herrmann, V.P.W. Bo¨hm, J. Organomet. Chem. 572
(1999) 141.
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