An easy entry into Schiff base molecules bearing a pendant primary alcohol function for hydrogen bonding

Article abstract of DOI:10.1055/s-2004-834943

A series of mono-oxidized pyridine, bipyridine, terpyridine and pyridine/pyridazine frameworks were prepared using MnO₂ as oxidant. Corresponding Schiff bases were prepared with aromatic or aliphatic amines carrying various functions such as pa

Full text of DOI:10.1055/s-2004-834943

PAPER
223
An Easy Entry into Schiff Base Molecules Bearing a Pendant Primary Alcohol
Function for Hydrogen Bonding
S
R
chif
f
Base Mole
a
cules
B
eari
y
ng a Pendan
m
t
Primary Alcohol
F
o
unction nd Ziessel,* Patrick Nguyen
Laboratoire de Chimie Moléculaire, Associé au CNRS, Ecole de Chimie, Polymères, Matériaux de Strasbourg (ECPM), 25 rue Becquerel,
7087 Strasbourg, Cedex 02, France
6
Fax +33(3)90242689; E-mail: ziessel@chimie.u-strasbg.fr
Received 27 July 2004; revised 22 September 2004
Abstract: A series of mono-oxidized pyridine, bipyridine, terpyri-
dine and pyridine/pyridazine frameworks were prepared using
N
MnO as oxidant. Corresponding Schiff bases were prepared with
N
N
Ar or R
2
aromatic or aliphatic amines carrying various functions such as par-
affin chains, terminal acrylates and a second nitrogen atom. Various
flexible tethers have been used for the ditopic ligands synthesis.
These ligands formed dinuclear helicates for the shorter chains. The
dinuclear copper(I) complex prepared from the CH –CH bridge is
aggregated in the solid state by a hydrogen bonded network of the
residual primary alcohol groups. For the longer spacers the ditopic
ligand wraps around a single copper(I) centre forming a mononucle-
ar complex. A significant merit of this work is that it allows the
preparation of ligands and complexes retaining the hydroxymethyl
function, which are likely to help to stabilize multidimensional net-
works in the solid state.
N
N
Ar or R
Ar or R
A
B
2
2
Ar or R
N
N
N
N
N
N
N
N
Ar or R
R or Ar
Ar or R
C
D
Key words: oligopyridines, Schiff bases, helicates, primary alco-
Figure 1 Binding behavior of imino-pyridine ligands
hols, hydrogen bonds
8
9
panation, homologation of aromatic aldehydes, and eth-
The development of the so-called Schiff base compounds ylene polymerization.10–12
has attracted a lot of interest in the fields of coordination
In the domain of material science, the main advantage in
the use of Schiff base ligands relates to the availability of
a free imino site that can be functionalized with a wide va-
riety of appendages, such as paraffin tails, highly polar-
ized molecular units or fragments bearing specific
physical properties. Along these lines we discovered that
assembling non-mesomorphic but lipid-like ligands bear-
ing in close proximity to the central core of two imino
1
,2
chemistry and material sciences. Metal complexes de-
rived from such useful derivatives are known to form a
large variety of molecular architectures, ranging from
macrocyclic helicates to infinite coordination polymers.3
In particular, 2-iminopyridine, 2,6-diiminopyridine and
,4
6
,6¢-diimino-2,2¢-bipyridine, readily formed via revers-
ible reaction between an achiral or chiral amine and ap-
propriate aldehydes, are attractive building blocks for
assembling intricate supramolecular species and highly
functions around d-block transition metals promotes the
13–15
formation of a liquid-crystalline state.
One of the key
5
,6
stable metallo-helicates. The presence of a lone pair on
the nitrogen atom of the imino group enables the coordi-
nation of numerous metal cations, especially when the
imine function is located at the ortho position of the het-
element of this approach lies in the helix rigidity and po-
larizability to counterbalance the flexibility and non-po-
larizability imported by the paraffin chains. It becomes
clear from the few examples we have in hand, that the use
of segmented ligands carrying hybrid function such as py-
ridines/imines certainly facilitate the interlocking of rigid
conformations. The ready availability of these Schiff-
based ligands, the simplicity of the purification proce-
dures, the mildness of the reaction conditions, and the
high yields allow the preparation of multigram scale ma-
terials.
7
erocycle such as pyridine. These ligands can display spe-
cific binding behavior towards metal cations, some are
reminiscent of 2,2¢-bipyridine as in A, 2,2¢:6¢,2¢¢-terpyri-
dine as in B and 2,6,2¢,6¢-quaterpyridine as in C
(
Figure 1). Notice that in this last case the ligand can
adopt a bridging mode of coordination of type D. Recent-
ly, various molecules found interesting applications as
ligands in various homogeneous catalytic reactions such
as hydrosilation, Mukaiyama aldolization and cyclopro-
Furthermore, the engineering of ligands carrying addi-
tional organizing vectors such as potential hydrogen bond
donors or p-p stacking facilities will promote the organi-
zation of matter in the liquid-crystalline or solid-phase.
The present work is motivated by such a concept targeting
the preparation of ligands retaining a hydroxymethyl
function on one side of the molecule. The easy way to
SYNTHESIS 2005, No. 2, pp 0223–0232
x
x
.
x
x
.2
0
0
5
Advanced online publication: 08.12.2004
DOI: 10.1055/s-2004-834943; Art ID: Z14804SS
Georg Thieme Verlag Stuttgart · New York
©

2
24
R. Ziessel, P. Nguyen
PAPER
generate such molecules would be to find a selective 25259296) in a stoichiometric ratio with 2,6-dihydroxy-
mono-oxidation of dihydroxymethyl oligopyridinic plat- methylpyridine was weakly active and solely provided the
forms.
mono-oxidized derivative 1, in CHCl at 60 °C. Other
3
sources such as MnO from Merck (No. 805958) was very
2
Indeed, the selective oxidation of a single primary alcohol
in 2,6-hydroxymethylpyridine is feasible but remains dif-
ficult and feasible only under harsh conditions. Typical
active and provided solely the di-oxidized compounds.
After some experimentation, we were pleased to find that
we could isolate compound 1 in 70% using a large excess
literature procedures utilize SeO (0.5 equiv) under re-
2
1
6
of MnO from Prolabo and extend the protocol to a family
2
fluxing pyridine. This is a major problem due to the tox-
icity, cost, product purity and low isolated yields. In our
hands, this was a significant issue that could not be over-
come by manipulating the experimental conditions. We
desired conditions that would be practical, inexpensive,
environmentally friendly, amenable to large-scale synthe-
sis and allow for substrate generality.
of oligopyridine derivatives as depicted in Scheme 1.
Chloroform gave the best yields probably due to a correct
mismatch between the solubility of products, the kinetic
of the reaction and the selectivity. In all cases the forma-
tion of the bis-aldehydes is inefficient (<5%) and the un-
reacted compounds could be easily recovered. Similar
trends were found for bipyridine, terpyridine and pyri-
dine/pyridazine derivatives (Scheme 1), opening an ave-
nue for the synthesis of sophisticated ligands.
The use of other metal reagents or catalysts has also been
developed to address this issue and manganese dioxide
has proved to be a valuable oxidizing agent for many
functional groups.1
7–19
It is likely that the difference of activity between the dif-
However, we noticed that 2,6-di-
ferent MnO suppliers is due the different nature of the
2
hydroxymethylpyridine was doubly oxidized to the dial-
2
0
crystalline phase and surface area. By mean of X-ray pow-
der diffraction it was possible to determined the nature of
dehyde in acceptable yield. Also, the hydroxymethyl
substituted aromatic heterocyles, including pyridines,
furans, and thiophenes are oxidized smoothly to the corre-
the MnO phase, likely to be a Pyrolusite phase for the
2
Prolabo sample and Akhtenskite for the MnO purchased
2
sponding aldehydes by 4-acetylamino-2,2,6,6-tetrameth-
from Merck.24 Also significant is the weak surface area
found by the Brunaüer–Emmett–Teller technique (BET),
ylpiperidine-1-oxoammonium perchlorate as reagent.21
Alternatively, 6-formyl-2-methylpyridine could be gener-
2
2
2
2
for the Prolabo sample (3.8 m /g) and 46.7 m /g for the
Merck sample. Furthermore, the morphology of both sam-
ples is different and it is concluded that the larger crystal
and lower surface area present in the Prolabo sample favor
a weaker activity resulting in the mono-oxidized sample.
The more dispersed Merck sample is highly active and
provide exclusively doubly oxidized derivatives.
ated by heterogeneous oxidation, whereas 6-formyl-6¢-
methyl-2,2¢-bipyridine and 6-formyl-5¢-methyl-2,2¢-bipy-
ridine could be prepared by a mono-oxidation of a single
methyl substituent by selenium dioxide in refluxing diox-
2
3
ane.
We found that depending of the source of commercially
available manganese dioxide, the selective mono-oxida-
tion of oligopyridine carrying dihydroxymethyl functions
could be achieved in appreciable yields. In particular, the
use of MnO2 from Rhône-Poulenc (Prolabo No.
One of the objectives of this study was to develop a con-
cise and practical synthesis of Schiff-based molecules and
their analogues to facilitate further evaluation in coordina-
tion chemistry and material sciences. The remaining hy-
H
OH
MnO2
O
N
N
n = 1, 2, 3
n
n
OH
OH
H
H
H
O
N
H
O
O
H
N
N
N
O
O
N
N
N
N
N
N
N
OH
HO
N
1, 70%
4
, 66%
OH
OH
2, 80%
OH
5
, 77%
3
, 54%
Scheme 1
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

PAPER
Schiff Base Molecules Bearing a Pendant Primary Alcohol Function
225
droxy groups will act as organizing vectors in the solid After some experimentation, we were pleased to find that
state in order to stabilize three-dimensional structures via these condensations can effectively been performed un-
hydrogen bonds (vide infra). This has led us to devise a der mild conditions and in fair yields. To avoid the trans-
flexible synthetic strategy, which employs the model esterification by-product with the free methyl alcohol
compound p-methoxyaniline as a template (Scheme 2). function and to achieve a better yield in the imine forma-
The condensations are straightforward when realized un- tion, we turned our attention to the use of trace amounts of
der stoichiometric conditions, in hot ethanol, in the pres- p-toluenesulfonic acid instead of acetic acid. Despite its
ence of trace amounts of acetic acid. The desired imino obvious advantages and potential utility, p-TsOH enabled
derivatives were recovered pure by filtration at room tem- the formation of the acrylate derivatives only in modest to
perature.
good yields (Figure 2).
2
5
In analogy to our previous work, and also stimulated by Encouraged by the successful preparation of the imino de-
our involvement in a program devoted to the engineering rivatives, we moved to the more ambitious goal of ex-
of mesomorphic nanostructures, 2-formyl-6-hydroxy- panding the methodology to the use of aliphatic diamino
methylpyridine was condensed with aniline derivative compounds in order to produce ditopic ligands for copper
bearing in the para position an additional phenyl ester di- complexation. Ligands 14 and 15 were successfully pre-
pole and carrying in its periphery three paraffin chains. In pared in almost quantitative yields, by condensation of
one case, one of these alkyl chain is substituted by an two equivalents of 2-formyl-6-hydroxymethylpyridine or
acrylate function, a potential module for controlled poly- 2-formyl-6-hydroxymethyl-2,2¢-bipyridine with ethyl-
merization reactions (Figure 2). Photo- or radical-initiated enediamine in the presence of trace amounts of acetic acid
polymerization reactions have already been applied to (Scheme 3).
generate stable anisotropic networks from reactive rod
In addition, in order to test the potential of the pyridine-
like liquid crystals in the nematic, cholesteric or smectic
based diimino ligands to bridge two cations or to wrap
phases. In this processes, monomers with reactive end
around a single metal we have increase the size of the
groups such as acrylates could be macroscopically aligned
spanning diamine from n = 2 to n = 5 (Scheme 4). Here
and polymerized in order to freeze the molecular organi-
also the condensation is straightforward in the presence of
trace amounts of acetic acid, but we noticed a progressive
2
6,27
zation in a rigid material.
OMe
H
H
O
N
N
N
n = 1, 2, 3
n
n
OH
OH
OMe
OMe
H
H
N
N
N
N
6, 96%
7, 75%
N
OH
HO
OMe
OMe
H
H
N
N
N
N
N
N
9, 86%
8, 82%
N
N
N
OH
OH
Scheme 2
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

2
26
R. Ziessel, P. Nguyen
PAPER
OC12H25
H
H
H
OC12H25
O
N
N
m
O
N
N
N
H
OC12H25
m = 3, 4, 5
O
N
OH
OH
HO
N
10, 84%
OC12H25
OC12H25
OH
H
H
N
N
O
O
H
OC12H24O
O
N
N
N
OH
HO
N
1
6, 70%
11, 51%
OH
HO
OC12H25
OC12H25
H
N
N
N
O
OC12H25
N
H
H
N
17, 63%
H
H
O
OH
N
N
N
N
N
12, 88%
OC12H25
N
OC12H25
OH
HO
1
8, 50%
HO
O
Scheme 4
OC12H24O
O
H
O
N
react
under
stoichiometric
conditions
with
N
2
8
[
Cu(CH CN) ](BF ) salts under anaerobic conditions.
3 4 4
13, 51%
Immediately after mixing the ligand with the metal salt, a
deep-red color characteristic of Cu-imino derivatives de-
velops in the solution. This coloration is indicative of a
N
HO
Figure 2 Pyridine or bipyridine Schiff bases 10–13
29
Cu(I) cation surrounded by four nitrogen donor atoms.
FT-IR studies in solution and the solid state of the result-
–1
ing complex show a 21 cm shift of the imino stretching
vibration, confirming that no free imino function is
present at 1650 cm–1 (C=N). Furthermore, the H NMR
spectrum of the isolated Cu-complex 19, reveals the pres-
ence of an AB system (exo-H: 4.57 ppm, J = 15.3 Hz;
endo-H: 3.77 ppm, J = 15.3 Hz), while in the free ligand a
singlet is found at 4.89 ppm. This prochirality of the meth-
ylene protons is consistent with rigidification of the imi-
nopyridine fragments due to the coordination to the metal
centre, but is not a tool to determine the helical nature of
HO
N
n
1
H
H
N
O
N
N
N
H
n = 1, 2
n
n
OH
OH
HO
OH
N
H
N
30
N
the resulting complex. ES-MS reveals the presence of an
N
H
N
+
intense molecular peak at 809.2 [M – BF ] and 361.1
N
H
N
4
N
2+
[
M – 2BF4] typical of a binuclear species (Figure 3). A
N
H
1
4, 87%
X-ray crystal structure unambiguously confirmed the for-
mation of a binuclear metallohelicate with the two cop-
per(I) centers being separated by 3.902 Å. The ligands
wraps around the two metal centers to give a double strand
helicate complex (Figure 4). The bond lengths and angles
around the copper cation are in good agreement with the
OH
N
1
5, 91%
HO
Scheme 3
29
values found in similar copper complexes. As expected,
the crystal structure is stabilized by hydrogen bond inter-
actions involving the four alcohol functions forming a
decrease of the isolated yields on increasing the number of
carbon atoms (Scheme 4).
In order to test the coordination abilities of such ligands tight multidimensional H-bonded network. Two different
towards transition metal and to generate simple metal in- hydrogen bonds interlink the dimeric structure along the
duced self-organized structures, ligand 14 was allowed to axis c; d = 2.874(9) Å and d = 2.944(11) Å (Figure 5). Re-
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

PAPER
Schiff Base Molecules Bearing a Pendant Primary Alcohol Function
227
2
+
OH
OH
N
N
Cu
2
BF4-
N
N
N
N
Cu
N
HO
HO
N
1
9, 70%
2
+
OMe
HO
+
H
N
BF4-
N
H
N
N
N
2 ClO4-
Cu
N
Cu
N
N
N
N
HO
HO
OH
2
0, 68%
MeO
2
1, 78%
Figure 3 Various copper complexes 19–21: top, double strand heli-
cate; bottom, mononuclear species
cently, similar polymeric arrays self-assembled by hydro-
3
1
gen bond aggregation have been evidenced.
At this stage, it was interesting to test the pyridine based
ligands 16, 17 and 18 in the formation of copper(I) com-
plexes. Interestingly, we found that ligand 17 bearing a
flexible 1,4-diiminobutane tether does not form the dou-
ble stranded helicate but rather give rise to a stable and
deep-red mono-nuclear complex 20 in which a single
ligand 17 wraps around a single copper(I) cation. ES-MS
Figure 5 Interlinked hydrogen bonded network running along the c
axis. (a) ball and stick view of the network. (b) CPK view.
reveals the presence of an intense molecular peak at 389.2
+
[
M – BF ] and the absence of a peak at higher mass typ-
4
Finally, in order to test the coordination abilities of a po-
tential tridentate ligand we mixed together two equiva-
lents of the tritopic ligand 7 with one equivalent of
Cu(H O) ·ClO . The instantaneous formation of the com-
ical of a dicationic species. The proton NMR of complex
0 reveals the presence of a single complex but does not
2
give the stoichiometry of the formed complex. Surprising-
ly, with ligands bearing a 1,2-diiminopropane or 1,5-diim-
inopentane spacer, mixtures of complexes were observed
2
6
4
plex was followed by observation of a deep-red color. As
expected for a copper(II) species in an octahedral environ-
ment, the resulting complex is paramagnetic and the FT-
1
under the standard conditions of reaction. Based on H
NMR and ES-MS data, it can be stated that in the case of
ligand 16 both mononuclear and binuclear are simulta-
neously formed, whereas, in the case of ligand 18 a mix-
ture of the mononuclear and polymeric complexes was
formed. Attempts to grow single crystals or to properly
separate these complexes remain elusive.
–1
IR reveal a 25 cm decrease of the C=N stretching vibra-
tion, a value typical for a strong interaction with the metal
+
center. FAB analysis is in keeping with a two ligand/one
copper stoichiometry with intense molecular peaks at
+
2+
8
00.2 [M – ClO ] , 350.6 [M – 2 ClO ] . A schematic
4
4
2
+
Figure 4 (a) ORTEP drawing of the [Cu (14) ] helicate 19 showing the 30% probability thermal ellipsoids. The hydrogen atoms are drawn
2
2
as small spheres of arbitrary radii. (b) CPK view of the binuclear complex. The counter anions were deleted for the sake of clarity.
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

2
28
R. Ziessel, P. Nguyen
PAPER
representation of the copper(II) complex is given in Anal. Calcd for C
Figure 3.
H
NO
(137.14): C, 61.31; H, 5.14; N, 10.21.
7
7
2
Found: C, 61.17; H, 4.87; N, 10.04.
In summary, we have described the preparation of mono-
formyl/monohydroxymethylpyridine based molecules. 6,6-Di(hydroxymethyl)-2,2¢-bipyridine (0.100 g, 0.463 mmol) was
Condensation with adequate primary amine or aniline de- oxidized with MnO
rivatives allows the facile formation of multitopic ligands
bearing a controlled number of donor atoms and methyl-
ene units in the spacer. When additional ester functions FT-IR (KBr): 3437s (OH), 2923s, 2863m, 1619m (C=O), 1384,
6
-Formyl-6¢-hydroxymethyl-2,2¢-bipyridine (2)
(2.65 g, 30 mmol) in CHCl (100 mL) for 3
2
3
days. After purification by chromatography (silica gel, pretreated
with Et N), 0.079 g of a white solid (80%) was obtained.
3
–
1
1
179, 1083 cm .
are present on the anilines, the use of p-TsOH versus ace-
tic acid is preferred in order to avoid transesterification of
the compounds. Some of these ligands formed stable
mono- and dinuclear complexes with Cu(I) salts. A cop-
per helicate was characterized by an X-ray diffraction
study. The tuning of the complex stoichiometry is feasible
by varying the flexibility and length of the bridging car-
1
H NMR (200 MHz, CDCl , 25 °C): d = 10.15 (s, 1 H), 8.67 (dd, 1
3
3
4
3
H, J = 7.5 Hz, J = 1.8 Hz), 8.50 (d, 1 H, J = 7.5 Hz), 8.00 (m, 2
3
3
H), 7.88 (t, 1 H, J = 7.5 Hz), 7.32 (d, 1 H, J = 7.5 Hz), 4.86 (s, 2
H), 3.62 (br s, 1 H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 193.6, 158.5, 152.4,
3
1
38.0, 137.8, 125.0, 121.5, 121.1, 120.0, 64.0.
+
+
bon chain. This approach has considerable potential ben- FAB -MS (m-NBA): m/z = 215.2 [M + H] .
efits in terms of simplifying the covalent synthesis. Some Anal. Calcd for C H N O (214.22): C, 67.28; H, 4.71; N, 13.08.
1
2
10
2
2
of these new ligands carry suitable acrylate fragments for Found: C, 66.96; H, 4.53; N, 12.78.
polymerization reactions, which makes these compounds
5
5
-Formyl-5¢-hydroxymethyl-2,2¢-bipyridine (3)
,5¢-Di(hydroxymethyl)-2,2¢-bipyridine (0.300 g, 1.39 mmol) was
an attractive and available template for material science.
We are currently exploring how to integrate further su-
pramolecular interactions to design even more sophisti-
cated templates based on multiple recognition events in
which hydrogen bonding and p-p stacking interactions are
privileged.
oxidized with MnO (7.95 g, 90 mmol) in CHCl (100 mL) for 2
days. After purification by chromatography (silica gel, pretreated
with Et N), 0.160 g of a white solid (54%) was obtained.
2
3
3
FT-IR (KBr): 3437s (OH), 2923s, 2863m, 1619m (C=O), 1384,
1
–1
179, 1083 cm .
1
H NMR (200 MHz,CDCl , 25 °C) : d = 10.17 (s, 1 H), 9.12 (d, 1
3
4
4
3
6
2
,6¢-Di(hydroxymethyl)-2,2¢-bipyridine,
5,5¢-dihydroxymethyl-
H, J = 2 Hz), 8.71 (d, 1 H, J = 2 Hz), 8.61 (d, 1 H, J = 8.0 Hz),
8.52 (d, 1 H, J = 8.0 Hz), 8.31 (dd, 1 H, J = 8.0 Hz, J = 2.0 Hz),
7.91 (d, 1 H, J = 8.0 Hz), 4.86 (s, 2 H).
3
3
4
,2¢-bipyridine, 6,6¢-dihydroxymethyl-2,2¢:6¢,2¢¢-terpyridine, 3,6-
3
2
3
di-(6-hydroxymethyl-2-pyridyl)-pyridazine, 4-{[3,4,5-tri(dodeca-
decyloxy)benzoyloxy]}aniline,
3
3
4-{[3,4-di(dodecadecyloxy)-5-
13
C NMR (50.3 MHz, CDCl , 25 °C): d = 190.6, 160.4, 154.1,
3
4
3
(11¢-methylacrylatedodecadecyloxy)]benzoyloxy}aniline,
[Cu(CH CN) ](BF ) were prepared and purified according to the
1
51.7, 148.2, 137.2, 136.9, 135.8, 122.1, 122.1, 121.3, 62.5.
28
3
4
4
+
+
FAB -MS (m-NBA): m/z = 215.1 [M + H] .
literature procedure. 2,6-Di(hydroxymethyl)pyridine, p-anisidine,
ethylene diamine, 1,2-diaminopropane, 1,4-diaminobutane, 1,5-di-
Anal. Calcd for C H N O (214.22): C, 67.28; H, 4.71; N, 13.08.
Found: C, 67.00; H, 4.62; N, 12.86.
1
2
10
2
2
aminopentane, and Cu(ClO ) ·6H O are commercially available.
4
2
2
Monocarbaldehydes 1–5 (Scheme 1); General Procedure
In a round-bottomed flask equipped with a condenser, the dihy-
droxymethyl substrate was dissolved in the given amount of CHCl3
6
6
-Formyl-6¢¢-hydroxymethyl-2,2¢:6¢,2¢¢-terpyridine (4)
,6¢-Dihydroxymethyl-2,2¢:6¢,2¢¢-terpyridine (0.500 g, 1.70 mmol)
was oxidized with MnO (9.72 g, 110 mmol) in CHCl (100 mL) for
2 days. After purification by chromatography (silica gel, pretreated
2
3
and MnO was added as a solid. The mixture vigorously stirred un-
2
der reflux for several days until most of the starting material was
consumed. After cooling to r.t., the suspension was filtered over
Celite with a glass frit. The mono-oxidized products were purified
by flash chromatography over silica gel using a mixture of solvents,
gradient CH Cl –MeOH (0 to 5%) as eluent. In some cases the silica
with Et N), 0.338 g of a white solid (66%) was obtained.
3
FT-IR (KBr): 3437s (OH), 2923s, 2863m, 1619m (C=O), 1384,
–
1
1
179, 1083 cm .
1
H NMR (200 MHz, CDCl , 25 °C): d = 10.11 (s, 1 H), 8.65 (d, 1
2
2
3
3
3
gel support was pre-treated with Et N. Most of the target molecules
H, J = 8.0 Hz), 8.51 (d, 2 H, J = 8.0 Hz), 7.97 (m, 3 H), 7.88 (t, 2
H, J = 8.0 Hz), 7.32 (d, 1 H, J = 8.0 Hz,), 4.86 (s, 2 H).
3
3
3
were directly obtained pure. In some cases, recrystallization from a
mixture of CH Cl and hexane was required.
2
2
13
C NMR (50.3 MHz, CDCl , 25 °C): d = 192.4, 160.7, 158.2,
3
1
1
54.5, 151.7, 150.5, 150.2, 137.9, 136.8, 124.1, 122.9, 121.8, 120.4,
20.2, 119.8, 119.3, 64.3.
2
2
-Formyl-6-hydroxymethylpyridine (1)
,6-Di(hydroxymethyl)pyridine (2.00 g, 14.37 mmol) was oxidized
+
+
FAB -MS (m-NBA): m/z = 292.1 [M + H] .
with MnO (81.00 g, 0.93 mol) in CHCl (200 mL) for 4 days. After
2
3
purification, a white solid (1.35 g, 70%) was obtained.
Anal. Calcd for C H N O (291.30): C, 70.09; H, 4.50; N, 14.42.
1
7
13
3
2
Found: C, 69.73; H, 4.26; N, 14.19.
FT-IR (KBr): 3437s (OH), 2920s, 2851m, 1619m (C=O), 1384,
–
1
1
333, 1259, 1113, 1037 cm .
3
(
3
-(6¢-Formylpyridyl)-6-(6¢-hydroxymethylpyridyl)pyridazine
5)
,6-Di(6-hydroxymethyl-2-pyridyl)pyridazine (0.300 g, 1.02
mmol) was oxidized with MnO (7.50 g, 86.27 mmol) in CHCl
1
H NMR (200 MHz, CDCl , 25 °C): d = 10.09 (s, 1 H), 7.89 (d, 2
3
3
3
H, J = 4.3 Hz), 7.52 (t, 1 H, J = 4.3 Hz), 4.88 (br s, 2 H), 3.59 (br
s, 1 H).
2
3
1
3
1
C{ H} NMR (50.3 MHz, CDCl , 25 °C): d = 193.0, 160.2, 152.3,
(200 mL) for 3 days. The oxidized monoproduct was purified by
chromatography (silica gel, pretreated with Et N), affording 0.230
3
1
38.2, 125.0, 121.3, 64.2.
3
+
+
mg (77%) of a white solid.
FAB -MS (m-NBA): m/z = 138.2 [M + H] .
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

PAPER
Schiff Base Molecules Bearing a Pendant Primary Alcohol Function
229
1
FT-IR (KBr): 3438s (OH), 2923s, 2857m, 1619m (C=O), 1432,
H NMR (200 MHz, CDCl , 25 °C): d = 8.75 (s, 1 H), 8.68 (d, 1 H,
3
3
–1
3
3
1
384, 1149, 1083 cm .
J = 8.0 Hz), 8.55 (d, 2 H, J = 8.0 Hz), 7.96 (m, 3 H), 7.86 (t, 2 H,
3
3
1
J = 8.0 Hz), 7.38 (d, 1 H, J = 8.0 Hz), 7.34 (d, AB system, J = 7.9
H NMR (200 MHz, CDCl , 25 °C): d = 10.20 (s, 1 H), 8.81 (m, 4
3
3
3
Hz, 2 H), 6.99 (d, AB system, J = 7.9 Hz, 2 H), 4.87 (s, 2 H), 3.86
s, 3 H).
H), 8.02 (m, 3 H), 7.40 (d, 1 H, J = 8.0 Hz), 4.90 (s, 2 H).
(
13
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 193.6, 160.4, 146.6,
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 162.9, 159.6, 158.6,
3
1
40.8, 138.4, 138.1, 125.7, 125.5, 121.8, 120.5, 64.2.
1
1
58.5, 158.0, 157.7, 155.7, 153.4, 143.6, 139.8, 138.9, 138.6, 126.5,
26.3, 124.5, 124.1, 123.5, 123.0, 121.8, 120.5, 64.4, 55.8.
+
+
FAB -MS (m-NBA): m/z = 293.2 [M + H] .
Anal. Calcd for C H N O (292.29): C, 65.75; H, 4.14; N, 19.17.
Found: C, 65.46; H, 3.94; N, 18.96.
+
+
16
12
4
2
FAB -MS (m-NBA): m/z = 397.2 [M + H] .
Anal. Calcd for C H N O (396.16): C, 72.71; H, 5.08; N, 14.13.
2
4
20
4
2
Found: C, 72.54; H, 5.00; N, 13.95.
Schiff Bases 6–9 (Scheme 2); General Procedure
In a round-bottomed flask equipped with a condenser, the monocar-
baldehyde derivative was dissolved in a minimum volume of EtOH,
and a stoichiometric amount of p-anisidine was added. After stirring
for 5 min at r.t., AcOH (one drop) was added and the mixture was
heated overnight at 80 °C. During the cooling process, a volumi-
nous precipitate appeared. After 1 h at –30 °C, the solid was collect-
ed by filtration using a glass frit and washed with a minimum
3
-[6-(4-Iminomethoxybenzene)-2-pyridyl]-6-[6-hydroxymeth-
yl-2-pyridyl)]pyridazine (9)
Reaction of 3-(6¢-formylpyridyl)-6-(6¢-hydroxymethylpyridyl)py-
ridazine (0.100 g, 0.342 mmol) with p-methoxyaniline (0.120 g,
0
.410 mmol) in EtOH (40 mL) containing AcOH (one drop) afford-
ed 0.117 g (86%) of 9.
amount of cold EtOH and Et O. In all cases the recovered pale yel-
low solids were analytically pure.
FT-IR (KBr): 3438s (OH), 2983m, 2956m, 1619m (C=N), 1503s,
1421s, 1382s, 1265s, 1092s, 896s cm .
2
–
1
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.74 (m, 5 H), 8.33 (d, 1 H,
3
2
-Hydroxymethyl-6-(4-iminomethoxybenzene)pyridine (6)
3
3
J = 7.9 Hz), 8.01 (m, 2 H), 7.40 (d, 1 H, J = 7.9 Hz), 7.39 (d, AB
Reaction of 2-hydroxymethyl-6-formylpyridine (0.100 g, 0.729
mmol) with p-methoxyaniline (0.0987 g, 0.802 mmol) in EtOH (20
mL) containing AcOH (one drop) afforded 0.177 mg (96%) of 6.
3
3
system, J = 7.9 Hz, 2 H), 6.98 (d, AB system, J = 7.9 Hz, 2 H),
4
.89 (s, 2 H), 3.86 (s, 3 H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 160.1, 158.1, 157.9,
3
FT-IR (KBr): 3437s (OH), 2918m, 2850m, 1619m (C=N), 1596s,
1
1
54.8, 153.1, 152.2, 137.9, 137.9, 125.1, 124.9, 122.9, 122.6, 122.3,
21.6, 120.3, 114.5, 64.2, 55.5.
–
1
1
448s, 1384s, 1112s, 791s cm .
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.72 (s, 1 H), 7.93 (m, 2 H),
+
+
3
FAB -MS (m-NBA): m/z = 398.2 [M + H] .
3
3
7
6
.56 (t, 1 H, J = 4.5 Hz), 7.32 (d, AB system, J = 7.9 Hz, 2 H),
3
Anal. Calcd for C H N O (397.44): C, 69.51; H, 4.82; N, 17.62.
Found: C, 69.32; H, 4.56; N, 17.41.
.96 (d, AB system, J = 7.9 Hz, 2 H), 4.89 (s, 2 H), 3.84 (s, 3 H).
23 19
5
2
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 160.8, 158.6, 154.7,
3
1
52.5, 152.3, 138.4, 125.4, 124.7, 120.9, 120.6, 64.3, 55.7.
Schiff Bases 10–13 (Figure 2); General Procedure
+
+
FAB -MS (m-NBA): m/z = 243.2 [M + H] .
In a round-bottomed flask equipped with a condenser, the monocar-
boxyaldehyde derivative was dissolved in a minimum volume of
EtOH, and stoichiometric amount of 4-[3,4,5-tri(dodecadecyl-
oxy)benzoyloxy]aniline or 4-{[3,4-di(dodecadecyloxy)-5-(11¢-me-
thylacrylatedodecadecyloxy)]benzoyloxy}aniline was added. After
stirring for a few min at r.t., one crystal of p-TsOH (ca. 1 mg) was
added and the solution was heated overnight at 80 °C. During the
heating process a voluminous precipitate appeared. After 1 h at
Anal. Calcd for C H N O (242.27): C, 69.41; H, 5.82; N, 11.56.
Found: C, 69.21; H, 5.64; N, 11.19.
14
14
2
2
6
-Hydroxymethyl-6¢-(4-iminomethoxybenzene)-2,2¢-
bipyridine (7)
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.100 g,
0
(
.467 mmol) with p-methoxyaniline (0.164 g, 0.560 mmol) in EtOH
25 mL) containing AcOH (one drop) afforded 0.112 g (75%) of 7.
–
30 °C, the solid was collected by filtration using a glass frit and
washed with a minimum amount of cold EtOH and Et O. In all cas-
es the recovered pale yellow solids were analytically pure.
2
FT-IR (KBr): 3437s (OH), 2918m, 2850m, 1619m (C=N), 1596s,
1
–
1
448s, 1384s, 1112s, 791s cm .
1
Ligand 10
H NMR (200 MHz, CDCl , 25 °C): d = 8.73 (s, 1 H), 8.46 (t, 2 H,
3
3
3
Reaction of 2-formyl-6-hydroxymethylpyridine (0.100 g, 0.729
J = 7.5 Hz), 8.25 (d, 1 H, J = 7.5 Hz), 7.94 (m, 1 H), 7.89 (m, 1 H),
3
mmol)
with
4-[3,4,5-tri(dodecadecyloxy)benzoyloxy]aniline
7
.36 (m, 1 H), 7.28 (d, AB system, J = 7.9 Hz, 2 H), 6.97 (d, AB
3
(0.558 mg, 0.729 mmol) in EtOH (30 mL) in the presence of p-
TsOH (one crystal) afforded 0.542 g (84%) of 10.
system, J = 7.9 Hz, 2 H), 4.87 (s, 2 H), 3.86 (s, 3 H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 162.6, 158.4, 158.9,
3
FT-IR (KBr): 3437s (OH), 2918m, 2850m, 1619m (C=N), 1596s,
1
1
58.2, 153.4, 145.6, 139.8, 138.9, 126.8, 124.7, 123.5, 123.0, 121.8,
20.5, 64.6, 55.9.
–
1
1
448s, 1384s, 1112s, 791s cm .
1
+
+
H NMR (200 MHz, CDCl , 25 °C): d = 8.64 (s, 1 H), 8.14 (d, 2 H,
J = 7.5 Hz), 7.84 (t, 1 H, J = 7.5 Hz), 7.32 (m, 6 H), 4.85 (s, 2 H),
FAB -MS (m-NBA): m/z = 320.2 [M + H] .
3
3
3
Anal. Calcd for C H N O (319.37): C, 71.46; H, 5.37; N, 13.16.
Found: C, 71.19; H, 5.11; N, 13.00.
19
17
3
2
4
.03 (m, 6 H), 1.83 (m, 60 H), 0.84 (m, 9 H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 167.2, 163.4, 158.7,
3
1
1
2
1
55.9, 152.3, 145.6, 145.4, 140.2, 139.3, 126.4, 124.9, 123.1, 122.9,
21.4, 119.7, 73.2, 72.8, 69.5, 64.6, 31.7, 30.4, 30.0, 29.6, 29.5,
9.3, 29.2, 29.1, 28.5, 26.1, 25.9, 25.6, 25.4, 24.7, 22.6, 18.2, 18.0,
4.0.
6
-Hydroxymethyl-6¢¢-(4-iminomethoxybenzene)-2,2¢:6¢,2¢¢-
terpyridine (8)
Reaction of 6-hydroxymethyl-6¢¢-formyl-2,2¢:6¢,2¢¢-terpyridine
(0.100 g, 0.332 mmol) with p-methoxyaniline (0.117 g, 0.398
mmol) in EtOH (30 mL) containing AcOH (one drop) afforded
.108 g (82%) of 8.
+
+
FAB -MS (m-NBA): m/z (%) = 885.2 (100, [M + H] ), 763.2 (30).
0
Anal. Calcd for C H N O (885.31): C, 75.97; H, 10.02; N, 3.16.
Found: C, 75.65; H, 9.81; N, 2.90.
5
6
88
2
6
FT-IR (KBr): 3437s (OH), 2918m, 2850m, 1619m (C=N), 1596s,
1
–
1
448s, 1384s, 1112s, 791s cm .
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

2
30
R. Ziessel, P. Nguyen
PAPER
+
+
Ligand 11
FAB -MS (m-NBA): m/z (%) = 1046.2 (100, [M + H] ), 847.2 (10).
Reaction of 2-hydroxymethyl-6-formylpyridine (0.100 g, 0.729
mmol) with 4-{[3,4-di(dodecadecyloxy)-5-(11¢-methylacrylate-
dodecadecyloxy)]benzoyloxy}aniline (0.621 g, 0.729 mmol) in
EtOH (30 mL) in the presencd of p-TsOH (one crystal), afforded
Anal. Calcd for C H N O (1046.47): C, 74.60; H, 9.15; N, 4.02.
Found: C, 74.27; H; 9.01; N, 3.87.
6
5
95
3
8
Schiff Bases 14–18 (Schemes 3 and 4); General Procedure
In a round-bottomed flask equipped with a condenser, the monocar-
baldehyde derivative was dissolved in a minimum volume of EtOH,
and half an equivalent of ethylenediamine was added. After stirring
for a few min at r.t., AcOH (one drop) was added and the solution
was heated overnight at 80 °C. After cooling to r.t., the solvent was
removed by rotary evaporation and the crude solid was triturated
with a minimum amount of cold EtOH, filtered and washed with
0
.360 g (51%) of 11.
FT-IR (KBr): 3437s (OH), 2918m, 2850m, 1619m (C=N), 1596s,
–
1
1
448s, 1384s, 1112s, 791s cm .
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.65 (s, 1 H), 8.17 (d, 2 H,
3
3
3
J = 7.5 Hz), 7.90 (t, 1 H, J = 7.5 Hz), 7.38 (s, 2 H), 6.97 (d, AB
3
3
system, J = 7.9 Hz, 2 H), 6.71 (d, AB system, J = 7.9 Hz, 2 H),
6
6
.09 (m, 1 H), 5.54 (m, 1 H), 4.85 (s, 2 H), 4.13 (m, 2 H), 4.03 (m,
H), 1.93 (s, 3 H), 1.65 (m, 60 H), 0.88 (m, 6 H).
Et O. The resulting yellowish solids were analytically pure.
2
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 167.3, 163.5, 158.7,
3
Bis(6-hydroxymethyl-2-iminopyridine)ethylenediamine (14)
Reaction of 2-formyl-6-hydroxymethylpyridine (0.400 g, 2.9
mmol) with ethylenediamine (0.096 g, 1.6 mmol) in EtOH (10 mL)
containing AcOH (one drop) afforded 0.376 g (87%) of 14.
1
1
2
1
8
55.9, 152.3, 145.6, 145.4, 140.2, 139.3, 126.4, 125.1, 124.3, 122.0,
15.6, 108.5, 73.3, 69.0, 65.3, 64.6, 31.7, 30.7, 30.6, 30.2, 29.6,
9.5, 29.4, 29.3, 29.1, 28.5, 26.0, 25.9, 25.6, 25.5, 24.7, 22.6, 18.2,
8.1, 14.1. FAB -MS (m-NBA): m/z (%) = 969.1 (100, [M + H] ),
47.2 (20).
+
+
FT-IR (KBr): 3220s (OH), 2904m, 2844m, 1650m (C=N), 1593s,
–
1
1
459s, 1027s, 999s, 970s, 789s cm .
Anal. Calcd for C H N O (969.41): C, 74.34; H, 9.57; N, 2.89.
Found: C, 74.02; H, 9.34; N, 2.49.
60
92
2
8
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.41 (s, 2 H), 7.90 (d, 2 H,
3
3
3
3
J = 7.7 Hz), 7.74 (dd, 2 H, J = 7.7 Hz), 7.28 (d, 2 H, J = 7.7 Hz),
4
.89 (s, 4 H), 4.07 (s, 4 H).
Ligand 12
1
3
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.100 g,
C NMR (50.3 MHz, CDCl , 25 °C): d = 161.9, 158.8, 157.4,
3
0
.467 mmol) with 4-[3,4,5-tri(dodecadecyloxy)benzoyloxy]aniline
138.8, 123.9, 123.6, 64.5, 54.7.
(
(
0.358 g, 0.467 mmol) in EtOH (25 mL) in the presence of p-TsOH
one crystal) afforded 0.396 g (88%) of 12.
+
+
FAB -MS (m-NBA): m/z = 299.1 [M + H] .
Anal. Calcd for C H N O (298.35): C, 64.41; H, 6.08; N, 18.78.
Found: C, 64.12; H, 5.86; N, 18.44.
1
6
18
4
2
FT-IR (KBr): 3220s (OH), 2904m, (CH), 2844m (CH), 1650m
–
1
(
1
3
C=N), 1593s, 1459s, 1027s, 999s, 970s, 789s cm .
H NMR (200 MHz, CDCl , 25 °C): d = 8.73 (s, 1 H), 8.52 (d, 1 H,
J = 8.0 Hz), 8.46 (d, 1 H, J = 8.0 Hz), 8.27 (d, 1 H, J = 8.0 Hz),
Bis(6-hydroxymethyl-6¢-imino-2,2-bipyridine)ethylenediamine
(15)
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.200 g,
0.934 mmol) with ethylenediamine (0.028 g, 0.467 mmol) in EtOH
(20 mL) in the presence of AcOH (one drop) afforded 0.385 g
(91%) of 15.
3
3
3
3
3
7
.99 (d, 1 H, J = 8.0 Hz), 7.92 (d, 1 H, J = 8.0 Hz), 7.85 (d, 1 H,
3
3
J = 8.0 Hz), 7.40 (m, 4 H), 7.29 (d, 2 H, J = 8.0 Hz), 4.86 (br s, 2
H), 4.03 (m, 6 H), 3.94 (br s, 1 H), 1.87–1.26 (m, 60 H), 0.87 (m, 9
H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 165.5, 161.5, 158.7,
FT-IR (KBr): 3220s (OH), 2904m, 2844m, 1650m (C=N), 1593s,
1459s, 1027s, 999s, 970s, 789s cm .
3
–
1
1
1
3
56.0, 154.8, 154.6, 153.4, 150.2, 149.0, 143.5, 138.0, 124.2, 123.0,
22.8, 122.6, 122.0, 121.1, 120.3, 109.0, 73.9, 73.5, 32.3, 30.6,
0.1-29.7, 26.5, 26.4, 23.1.
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.52 (s, 2 H), 8.44 (dd, 2
3
3
4
3
H, J = 7.7 Hz, J = 1.8 Hz), 8.36 (d, 2 H, J = 7.7 Hz), 8.06 (dd, 2
H, J = 7.7 Hz, J = 1.8 Hz), 7.84 (m, 4 H), 7.24 (d, 2 H, J = 7.7
+
+
3
4
3
FAB -MS (m-NBA): m/z (%) = 962.2 (100, [M + H] ), 763.2 (15).
Hz), 4.83 (s, 4 H), 4.12 (s, 4 H).
Anal. Calcd for C H N O (962.39): C, 76.13; H, 9.53; N, 4.37.
Found: C, 75.78; H; 9.23; N, 4.03.
61
91
3
6
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 161.9, 158.6, 157.4,
3
1
56.7, 137.9, 137.8, 123.9, 123.2, 118.9, 118.6, 64.5, 54.7.
Ligand 13
+
+
FAB -MS (m-NBA): m/z = 453.2 [M + H] .
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.100 g,
Anal. Calcd for C H N O (452.52): C, 69.01; H, 5.35; N, 18.57.
Found: C, 68.75; H, 5.12; N, 18.19.
0
.467 mmol) with 4-{[3,4-di(dodecadecyloxy)-5-(11¢-methylacryl-
26 24
6
2
atedodecadecyloxy)]benzoyloxy}aniline (0.398 mg, 0.467 mmol)
in EtOH (30 mL) in the presence of p-TsOH (one crystal) afforded
Bis(6-hydroxymethyl-6¢-imino-2,2¢-bipyridine)propylenedi-
amine (16)
0
.239 mg (51%) of 13.
FT-IR (KBr): 3220s (OH), 2904m, 2844m, 1650m (C=N), 1593s,
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.200 g,
–
1
1
459s, 1027s, 999s, 970s, 789s cm .
0
.934 mmol) with 1,3-diaminopropane (0.035 g, 0.467 mmol) in
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.74 (s, 1 H), 8.54 (d, 1 H,
EtOH (20 mL) containing AcOH (one drop) afforded 0.102 g (70%)
of 16.
3
3
3
3
J = 8.0 Hz), 8.43 (d, 1 H, J = 8.0 Hz), 8.25 (d, 1 H, J = 8.0 Hz),
3
3
7
.93 (d, 1 H, J = 8.0 Hz), 7.93 (d, 1 H, J = 8.0 Hz), 7.91 (d, 1 H,
FT-IR (KBr): 3222s (OH), 2906m, 2850m, 1652m (C=N), 1595s,
3
J = 8.0 Hz), 7.80 (m, 4 H), 7.36 (d, 2 H), 6.10 (m, 1 H), 5.54 (m, 1
–1
1
462s, 1029s, 1000s cm .
H), 4.90 (br s, 2 H), 4.15 (m, 2 H), 4.05 (m, 6 H), 3.97 (br s, 1 H),
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.43 (s, 2 H), 7.92 (d, 2 H,
1
.95 (br s, 3 H), 1.90–1.23 (m, 60 H), 0.88 (m, 6 H).
3
3
3
3
J = 7.7 Hz), 7.78 (dd, 2 H, J = 7.7 Hz), 7.31 (d, 2 H, J = 7.7 Hz),
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 166.4, 165.3, 158.7,
3
3
4
.92 (s, 4 H), 3.97 (t, J = 6.9 Hz, 4 H), 2.79 (m, 2 H).
1
1
3
2
56.0, 154.8, 154.6, 153.4, 152.9, 150.2, 144.5, 142.9, 142.7, 136.4,
25.0, 124.2, 122.1, 115.5, 108.4, 73.4, 73.2, 69.1, 65.4, 64.7, 31.8,
0.6, 30.7, 30.2, 29.6, 29.6, 29.5, 29.4, 29.3, 29.2, 28.5, 26.0, 25.9,
5.6, 25.4, 24.7, 22.6, 18.2, 18.0, 14.0.
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 162.3, 158.6, 157.5,
3
1
38.9, 124.0, 123.8, 64.7, 54.7, 36.0.
+
+
FAB -MS (m-NBA): m/z = 313.1 [M + H] .
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

PAPER
Schiff Base Molecules Bearing a Pendant Primary Alcohol Function
231
Anal. Calcd for C H N O (312.37): C, 65.37; H, 6.45; N, 17.94.
diately after mixing at r.t., a deep-red solution was formed charac-
17
20
4
2
Found: C, 65.20; H, 6.26; N, 17.74.
teristic of a fast complexation process. After complete addition, the
solution was stirred for 1 h and Et O was allowed to slowly diffuse
2
Bis(6-hydroxymethyl-6¢-imino-2,2¢-bipyridine)butylenedi-
amine (17)
through the solution. The precipitate was collected and dried under
high vacuum; yield: 68%.
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.200 g,
FT-IR (KBr): 3445s (OH), 2906m, 2855m, 1629m (C=N), 1593s,
0
.934 mmol) with 1,4-diaminobutane (0.041 g, 0.467 mmol) in
–1
1
463s, 1084s, 999s, 973s cm .
EtOH (20 mL) containing AcOH (one drop) afforded 0.096 g (63%)
of 17.
1
H NMR (200 MHz, acetone-d , 25 °C): d = 8.86 (s, 2 H), 8.21 (d,
6
3
3
4
2
2
H, J = 7.7 Hz), 8.00 (dd, 2 H, J = 7.7 Hz, J = 1.8 Hz), 7.72 (d,
FT-IR (KBr): 3218s (OH), 2907m, 2840s, 1652m (C=N), 1595m,
3
H, J = 7.7 Hz), 4.75 (s, 4 H), 4.49 (m, 2 H), 4.21 (m, 2 H), 3.03
–
1
1
462s, 1029s, 1002s cm .
(
m, 4 H).
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.44 (s, 2 H), 7.92 (d, 2 H,
+
+
3
FAB -MS (m-NBA) m/z = 389.2 [M – BF ] .
3
3
3
4
J = 7.8 Hz), 7.75 (dd, 2 H, J = 7.8 Hz), 7.32 (d, 2 H, J = 7.8 Hz),
3
Anal. Calcd for C H BCuF N O ·MeCN (476.74 + 41.05): C,
4
.93 (s, 4 H), 3.99 (t, J = 6.8 Hz, 4 H), 2.81 (m, 4 H).
18 22
4
4
2
4
6.39; H, 4.87; N, 13.53. Found: C, 46.21; H, 4.65; N, 13.34.
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 161.6, 158.9, 157.6,
3
1
38.7, 123.7, 123.9, 64.7, 54.6, 29.7.
Mononuclear Copper(II) Complex 21
+
+
FAB -MS (m-NBA): m/z = 327.1 [M + H] .
An MeCN solution (10 mL) containing Cu(ClO ) ·6H O (0.056 g,
4
2
2
0
.144 mmol) was added dropwise to a CH Cl solution (5 mL) con-
2 2
Anal. Calcd for C H N O (326.39): C, 66.24; H, 6.79; N, 17.17.
Found: C, 66.03; H, 6.53; N, 17.00.
18
22
4
2
taining ligand 7 (0.092 g, 0.288 mmol). After 2 h, Et O was layered
over the previous solution and after a few days the solid formed was
2
collected by filtration over a glass frit affording complex 21; yield:
Bis(6-hydroxymethyl-6¢-imino-2,2¢-bipyridine)pentylenedi-
amine (18)
7
8% (0.101 g).
Reaction of 6-hydroxymethyl-6¢-formyl-2,2¢-bipyridine (0.200 g,
FT-IR (KBr): 3398s (OH), 2974m, 2857m, 1598m (C=N), 1505s,
1466s, 1434s, 1252s, 1085s, 999s, 975s cm .
–
1
0
.934 mmol) with 1,5-diaminopentane (0.048 g, 0.467 mmol) in
EtOH (20 mL) containing AcOH (one drop) afforded 0.079 g (50%)
8.
+
+
FAB -MS (m-NBA): m/z = 800.2 [M – ClO ] , 350.6 [M – 2
4
1
2+
ClO ] .
4
FT-IR (KBr): 3225s (OH), 2906m, 2848m, 1654m (C=N), 1599m,
Anal. Calcd for C H Cl CuN O (901.18): C, 50.65; H, 3.80; N,
–
1
38 34
2
6
8
1
464m, 1024s, 1004m cm .
9
.33. Found: C, 50.57; H, 3.55; N, 9.00.
1
H NMR (200 MHz, CDCl , 25 °C): d = 8.40 (s, 2 H), 7.93 (d, 2 H,
3
3
3
3
J = 7.7 Hz), 7.74 (dd, 2 H, J = 7.7 Hz), 7.29 (d, 2 H, H, J = 7.7
3
References
Hz), 4.90 (s, 4 H), 4.02 (t, J = 6.8 Hz, 4 H), 2.74 (m, 6 H).
1
3
C NMR (50.3 MHz, CDCl , 25 °C): d = 161.7, 158.9, 157.3,
(1) (a) Nelson, S. M. Pure Appl. Chem. 1980, 52, 2461.
(b) Bush, D. H.; Vance, A. L.; Kolchinski, A. G. In
Comprehensive Supramolecular Chemistry, Vol. 9;
Sauvage, J.-P.; Hosseini, M. W., Eds.; Pergamon: Oxford,
1996, 1–42. (c) Vance, A. L.; Alcock, N. W.; Heppert, J. A.;
Busch, D. H. Inorg. Chem. 1998, 37, 6912.
3
1
38.9, 124.2, 123.7, 64.7, 54.8, 32.8, 27.3.
+
+
FAB -MS (m-NBA): m/z = 341.1 [M + H] .
Anal. Calcd for C H N O (340.42): C, 67.04; H, 7.11; N, 16.46.
Found: C, 66.87; H, 6.96; N, 16.33.
19
24
4
2
(
(
2) Ziessel, R. Coord. Chem. Rev. 2001, 216-217, 195.
3) Brooker, S.; Kelly, R. J.; Plieger, P. Chem. Commun. 1998,
Dinuclear Copper(I) Complex 19
Ligand 14 (0.100 g, 0.335 mol) was dissolved in argon-degassed
1079.
CH Cl2 (15 mL) and added dropwise to
a
solution of
2
(4) Bowyer, P. K.; Porter, K. A.; Rae, A. D.; Willis, A. C.; Wild,
[
Cu(CH CN) ](BF ) (0.106 g, 0.338 mol) in MeCN (10 mL). Imme-
3
4
4
S. B. Chem. Commun. 1998, 1153.
5) Hannon, M. J.; Painting, C. L.; Jackson, A.; Hamblin, J.;
diately after mixing at r.t., a deep-red solution formed that is char-
acteristic of a fast complexation process. After complete addition,
the solution was stirred for 1 h and Et O was allowed to slowly dif-
fuse through the solution. The deep-red mono-crystals were collect-
ed and dried under high vacuum; yield: 89%.
(
Errington, W. Chem. Commun. 1997, 1807.
2
(6) Ziessel, R.; Harriman, A.; Suffert, J.; Youinou, M.-T.; De
Cian, A.; Fischer, J. Angew. Chem., Int. Ed. Engl. 1997, 36,
2509.
FT-IR (KBr): 3445s (OH), 2906m, 2855m, 1629m (C=N), 1593s,
(7) Douce, L.; El-ghayoury, A.; Skoulios, A.; Ziessel, R. Chem.
Commun. 1999, 2033.
–
1
1
463s, 1084s, 999s, 973s cm .
(
8) Dias, E. L.; Brookhart, M.; White, P. S. Chem. Commun.
001, 423.
9) Dias, E. L.; Brookhart, M.; White, P. S. J. Am. Chem. Soc.
001, 123, 2442.
1
H NMR (200 MHz, acetone-d , 25 °C): d = 8.82 (s, 2 H), 8.13 (dd,
6
2
3
4
3
2
H, J = 7.7 Hz, J = 1.8 Hz), 7.90 (d, 2 H, J = 7.7 Hz), 7.59 (d, 2
(
3
H, J = 7.7 Hz), 4.71 (s, 4 H), 4.45 (d, AB system, J = 15.3 Hz, 2 H),
2
4
.17 (d, AB system, J = 15.3 Hz, 2 H).
(
(
10) (a) Small, B. L.; Brookhart, M.; Bennett, A. M. A. J. Am.
Chem. Soc. 1998, 120, 4049. (b) Small, B. L.; Brookhart, M.
J. Am. Chem. Soc. 1998, 120, 7143. (c) Britovsek, G. J. P.;
Gibson, V. C.; Kimberley, B. S.; Maddox, P. J.; McTavish,
S. J.; Solan, G. A.; White, A. J. P.; Williams, D. J.; Bruce,
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Chem. Soc. 1999, 121, 8728.
+
+
FAB -MS (m-NBA): m/z (%) = 809.2 [M – BF ] , 361.1 [M –
2
4
2
+
BF ] .
4
Anal. Calcd for C H B Cu F N O (897.38): C, 42.83; H, 4.04; N,
32
36
2
2
8
8
4
1
2.49. Found: C, 42.54; H, 3.89; N, 12.14.
Mononuclear Copper(I) Complex 20
Ligand 17 (0.100 g, 0.306 mol) was dissolved in argon degassed
11) Haddleton, D. M.; Duncalf, D. J.; Kukulj, D.; Heming, A.
M.; Shooter, A. J.; Clark, A. J. J. Mater. Chem. 1998, 8,
CH Cl2 (15 mL) and added dropwise to
a
solution of
2
1525.
[
Cu(CH CN) ](BF ) (0.048 g, 0.153 mol) in MeCN (10 mL). Imme-
3
4
4
Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York

2
32
R. Ziessel, P. Nguyen
PAPER
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Synthesis 2005, No. 2, 223–232 © Thieme Stuttgart · New York