Synthesis of triscatechol derivatives - Building blocks with an idealized C3-symmetry for metallo-supramolecular chemistry

Article abstract of DOI:10.1055/s-2004-829159

A series of triscatechols with an idealized axis of C₃-symmetry were synthesized. Hereby amide, imine or direct bonds are introduced as linkage between the catechol units and various C₃-symmetric backbones.

Full text of DOI:10.1055/s-2004-829159

PAPER
1977
Synthesis of Triscatechol Derivatives – Building Blocks with an Idealized
C -Symmetry for Metallo-Supramolecular Chemistry
3
a
a
b
T
M
riscatechol
D
erivativ
a
a
Institut für Organische Chemie, RWTH-Aachen, Professor-Pirlet-Straße 1, 52074 Aachen, Germany
Fax +49(241)8092385; E-mail: markus.albrecht@oc.rwth-aachen.de
b
Organisch-Chemisches Institut, Universität Münster, Corrensstraße 44, 48149 Münster, Germany
Received 11 March 2004; revised 26 April 2004
Abstract: A series of triscatechols with an idealized axis of C3-
symmetry were synthesized. Hereby amide, imine or direct bonds
are introduced as linkage between the catechol units and various C3-
symmetric backbones.
Key words: Pd-coupling, amide, imine, catechol, ligand
Metallo-supramolecular chemistry is a still growing field
of research in which structural as well as functional as-
1
pects play an important role. In order to perform system-
atic studies, it is essential to have simple and versatile
entries to prepare appropriate ligands which can be intro-
duced into metal-directed self-assembly processes.2
Just recently, we described the formation of a huge su-
pramolecular tetrahedron 1 (Figure 1) which is assembled
from four rigid planar triscatecholate ligands 2 and four ti-
tanium(IV) ions in the presence of potassium, sodium or
lithium cations. Due to its size, the tetrahedron is able to
encapsulate guests in its interior and exchange of the guest
1
OH
OH
OH
OH
OH
N
OH
N
N
N
N
3
species can be investigated.
3
N
In addition, we found that the flexible ligand 3 as well is
able to form a related tetrahedron if no influences are ac-
HO
HO
4
tive which favor the formation of other structures. The
OH
N
N
conformation at the imine unit plays a crucial role in the
control of the assembly of different supramolecular aggre-
HO
HO
2
5
gates.
OH
In metal complexes catechol imines usually prefer the
Figure 1 Part of the X-ray structure of 1 and the triscatechol ligands
conformation A with the lone pair at nitrogen directing 2 and 3
away from the negatively charged catecholate oxygen at-
oms. However, this repulsion can be compensated by
echol amides between OH and the amide carbonyl oxygen
atom E. In aryl catechols there is no significant confor-
mational difference between the coordinated ligand C and
the uncoordinated one F (Figure 2).
5
binding with metal ions (A¢). A similar conformational
6
situation as in A¢ is observed for catecholate amides B
with a hydrogen bond connecting the nitrogen and oxygen
atom. Due to the preferred conformations, A adopts a
more open (‘bigger’) structure as A¢ or B does. The geom-
etry of an aryl catechol C can be described as ‘somewhere
in between’ (Figure 2).
6
In this paper we describe the preparation of a series of
triscatechol ligands, which in their idealized form possess
7
an axis of C -symmetry. Hereby catechol imines are pre-
3
pared by imine formation (e.g. following a Sonogashira
coupling reaction), catechol amides are obtained by sim-
ple condensation, and aryl catechol derivatives are formed
by Suzuki coupling.
In the free ligands, the situation is different. In the imine,
hydrogen bonding (or partial hydrogen transfer) occurs
between the internal hydroxyl group and the imine nitro-
5
gen D. Similar hydrogen bonding is observed in the cat-
Catechol Amides
SYNTHESIS 2004, No. 12, pp 1977–1982
x
x.
x
x
.
2
0
0
4
Advanced online publication: 27.07.2004
DOI: 10.1055/s-2004-829159; Art ID: Z04604SS
Georg Thieme Verlag Stuttgart · New York
A triscatechol amide 4 with an axis of C -symmetry was
described by Raymond et al. and a corresponding tetranu-
3
©

1
978
M. Albrecht et al.
PAPER
O
O
O
O
O
O
HO
HO
M
M
M
M
O
O
H
M'
O
NH
N
N
O
N
O
OH
A
A'
B
C
OH
HN
N
H
OH
OH
O
O
O
O
H
H
4
OH
O
H
OH
H
N
HN
O
F
D
E
N
NH2
Figure 2 Preferred conformations at a catecholate imine, catechola-
te amide, or catecholate aryl complex
MeO
O
OMe
HBTU,
3
6
i
EtN(Pr)2
78 %
MeO
OMe
N
NH
+
3
O
3
clear tetrahedral metal complex was obtained by self-as-
sembly. However, ligand 4 is rather small which leads to
a metal complex with a cavity, which is too small for the
OH
OH
8
7
OH
O
8
encapsulation of guest species. Therefore, we prepared
the larger derivative 5 by condensation of tris(4-ami-
nophenyl)amine (6) with three equivalents of 2,3-
dimethoxybenzoic acid (7) by activation with HBTU [O-
HN
BBr3
5 %
(
1-benzotriazolyl)-N,N,N¢,N¢-tetramethyluronium hexa-
9
9
N
NH
O
fluorophosphate] and ethyldiisopropylamine. The ob-
tained protected compound 8 is reacted with BBr to yield
3
1
0
O
HO
OH
the unprotected ligand 5 in 95% (Scheme 1). Ligand 5
HO
HO
NH
and its precursor 8 are characterized by standard methods.
5
Catechol Imines
Scheme 1 Raymond’s triscatechol amide 4 and preparation of the
related compound 5
The preparation of compound 3 from tris(2-aminoeth-
yl)amine and 2,3-dihydroxybenzaldehyde (10) was al-
1
1
ready described by Vigato et al. The catechol imine 2
analogously is formed by simple condensation of tris(4-
aminophenyl)amine with three equivalents of 2,3-dihy-
droxybenzaldehyde (10) in methanol. The product precip-
itates and can be isolated by filtration. Thus, the
H2N
NH2
Br
Br
Lit.
62 % (Lit.: 66 %)
3
9
Br
triscatechol imine 2 is obtained in 85% yield.
The triscatechol imine 11 is obtained starting from 1,3,5-
tribromobenzene. In a Sonagishira coupling reaction,
which was published recently, three equivalents of 4-alky-
nylaniline are attached to the 1,3,5-benzene platform in
OH
NH2
HO
HO
6
2% yield in the presence of bis(triphenylphosphane)pal-
1
2
OH
N
N
ladium dichloride and copper(I) iodide. The thus ob-
tained triamine 9 is reacted with the aldehyde 10 in
methanol, as was described for the preparation of 2 and 3,
and the ligand 11 is obtained in 86% as an orange solid
O
OH
OH
(
Scheme 2). Compound 11 represents a large and rigid
3
1
0
triscatechol imine ligand, which is even bigger than ligand
2
.
11
methanol
6 %
8
N
OH
OH
Scheme 2 Preparation of the triscatechol imine 11
Synthesis 2004, No. 12, 1977–1982 © Thieme Stuttgart · New York

PAPER
Triscatechol Derivatives
1979
The hydrogen-bonding interactions, which are shown in tallization from methanol, we obtained the ligand precur-
1
Figure 2, D and E, are reflected in the H NMR chemical sors in 71% (15) or 88% (16) yield, respectively.
shifts of 5, 2, 3, or 11 in DMSO-d . The signal of the OH
6
The methyl ether groups of compounds 15 and 16 are
groups in 3-position is shifted to low field due to hydrogen
bonding to the neighboring OH-group in 2-position. The
resonances appear at d = 9.90 (5), 9.17 (2), 8.80 (3) and
10
cleaved by reaction with BBr in dichloromethane.
3
Hereby, the smaller triscatechol 17 is isolated in 97%
yield, while the bigger derivative 18 is obtained in 98%
9
.29 (11). Additionally, very strong hydrogen bonding oc-
(
Scheme 3).
curs between OH in 2-position and either the imine nitro-
gen or the carbonyl oxygen, resulting in shifts d = 11.80
(
5), 13.30 (2), 13.71 (3) and 12.93 (11). The pronounced
low field shift of the signal in case of the imines compared
to the amides represents a partial proton transfer from hy-
5
,13
droxide to the imine nitrogen,
which is observed in
many salicyl imine derivatives (vide infra).
We were able to obtain crystals of compound 3 which
were suitable for an X-ray structure analysis (Figure 3). In
the solid state 3 adopts a bowl shaped arrangement with
the triethylamine moiety defining the curvature of the
bowl and the three catechol imines forming the wall. One
of the three catechol imine units adopts a form as repre-
sented by structure D. Here the distances within the
N···H–O system are 1.09 Å (H–O) and 1.54 Å (N···H).
The other two catechols show a structure, which can be
described as the keto enamine D¢. Proton transfer between
OH and =N occurs, leading to short N–H distances of 0.90
and 0.92 Å, while the distances between O and H are long
with 1.84 and 1.78 Å, respectively. Proton transfer in the
phenol imine/keto enamine system is well known and
leads to thermo- as well as photochromic behavior of such
5
,11,13
compounds.
Scheme 3 Preparation of the triscatechol aryl derivatives 17 and 18
In conclusion, we have presented the preparation of three
different types of triscatechol ligands with catechol
amide, imine, or aryl connectivity. The derivatives pos-
sess an axis of C -symmetry and they should be appropri-
3
ate building blocks for the metal-directed self-assembly of
supramolecular tetrahedra.
Figure 3 Solid-state structure of 3 and two different forms of the ca-
techol imine units as observed in the solid state
The different compounds possess edges of different
lengths of the idealized triangular structure (which is rep-
resented by the distance between two hydrogen atoms in
Catechol Aryl Derivatives
4
-position of two catechol moieties). Models of the
Catechol aryl derivatives are prepared by Suzuki coupling
reaction of 2,3-dimethoxyphenylboronic acid (12) with
the tribromoaryl derivatives 13 and 14 in the presence of
ligands show that this size varies from 11 to 27 Å
1
4
(
Figure 4).
1
5
Pd(PPh ) and Na CO in toluene–ethanol. After recrys-
3
4
2
3
Synthesis 2004, No. 12, 1977–1982 © Thieme Stuttgart · New York

1
980
M. Albrecht et al.
PAPER
H NMR (DMSO-d , 400 MHz): d = 11.80 (br, 3 H), 10.33 (s, 3 H),
1
H
6
9
.90 (br, 3 H), 7.64 (d, J = 8.8 Hz, 6 H), 7.45 (dd, J = 8.0, 1.4 Hz, 3
OH
H), 7.05 (d, J = 8.8 Hz, 6 H), 6.98 (dd, J = 8.0, 1.4 Hz, 3 H), 6.77 (t,
J = 8.0 Hz, 3 H).
X
X =
OH
5
2
3
20.4 Å
20.1 Å
~17.2 Å
13
C NMR (DMSO-d , 100 MHz): d = 168.0 (C), 149.0 (C), 146.6
OH
6
(
C), 144.0 (C), 134.4 (C), 133.4 (C), 124.1 (CH), 123.1 (CH), 119.4
HO
11 27.4 Å
7 11.8 Å
8 19.3 Å
1
1
(CH), 118.8 (CH), 117.2 (CH).
HO
H
+
MS (EI): m/z = 698 ([M ]).
OH
Anal. Calcd for C H N O : C, 67.04; H, 4.33; N, 8.02. Found: C,
3
9
30
4
9
Figure 4 Length of the edges of the triangular triscatechols
66.88; H, 4.21; N, 8.38.
Triscatechol Imines 2 and 3; General Procedure
The triamine (ca. 0.5 mmol, 1 equiv) and dihydroxybenzaldehyde
While we already could show that 2 and 3 form molecular
tetrahedra, coordination studies with the other ligands are
1
0 (3 equiv) were dissolved in MeOH (20 mL). The color of the so-
currently performed in our laboratories. The formation of lution turned to orange and after a short period of time, the triimine
tetrahedra of varying size should enable a fine tuning of started to precipitate. After standing overnight, the product was iso-
lated by filtration, washed with cold MeOH and dried in vacuum.
the interaction with different guest species.
N,N¢,N¢¢-Tri(2,3-dihydroxybenzylidene)-4,4¢,4¢¢-triaminotriphe-
1H and 13C NMR spectra were recorded on a Varian Inova 400 spec-
trometer. FT-IR spectra were recorded by diffuse reflection (KBr)
or neat on a Bruker IFS spectrometer. Mass spectra (EI, 70 eV;
FAB) were taken on a Finnigan MAT 95 or 212 mass spectrometer.
Elemental analyses were obtained with a Heraeus CHN-O-Rapid
analyzer. Melting points: Büchi B-540 (uncorrected). The com-
nylamine (2)
Yield: 343 mg (85%); red solid; mp 220 °C (dec.); R = 0.34
f
(CH Cl –MeOH, 20:1).
2
2
IR (KBr): 3416, 1619, 1504, 1462, 1366, 1322, 1273, 1208, 1028,
–
1
8
71, 836, 781, 734, 558 cm .
1H NMR (DMSO-d
, 400 MHz): d = 13.30 (br, 3 H), 9.17 (br, 3 H),
8.94 (s, 3 H), 7.45 (d, J = 8.8 Hz, 6 H), 7.16 (d, J = 8.8, 6 H), 7.09
dd, J = 7.8, 1.4 Hz, 3 H), 6.94 (dd, J = 7.8, 1.4 Hz, 3 H), 6.79 (t,
J = 7.8 Hz, 3 H).
pounds 6,16 9, and 12 were prepared as described in the litera-
12
14
6
ture.
(
N,N¢,N¢¢-(Nitrilotri-4,1-phenylene)tris(2,3-dimethoxybenz-
amide) (8)
+
MS (EI): m/z = 650 ([M ]).
2
,3-Dimethoxybenzoic acid (7; 188 mg, 1.03 mmol), HBTU (470
Anal. Calcd for C H N O ·0.5H O: C, 71.01; H, 4.74; N, 8.49.
mg, 1.24 mmol) and ethyldiisopropylamine (147 mg, 1.14 mmol)
were dissolved in MeCN (25 mL). Tris(4-aminophenyl)amine (6;
39 30
4
6
2
Found: C, 70.77; H, 4.93; N, 8.56.
1
00 mg, 0.34 mmol) was added after 20 min. The mixture was
N,N¢,N¢¢-Tri(2,3-dihydroxybenzylidene)-2,2¢,2¢¢-triaminotrieth-
stirred at r.t. for 2 d and the solvent was removed in vacuo. The res-
idue was dissolved in EtOAc and the organic phase was dried
1
1
ylamine (3)
Yield: 442 mg (85%); yellow solid.
(
(
MgSO ) and the solvent was removed in vacuum to obtain 210 mg
78%) of 8 as a green solid; mp 192 °C (dec.).
4
1
H NMR (DMSO-d , 400 MHz): d = 13.71 (br, 3 H), 8.80 (br, 3 H),
6
8
.24 (s, 3 H), 6.79 (dd, J = 7.7, 1.9 Hz, 3 H), 6.50 (t, J = 7.7 Hz, 3
IR (KBr): 3319, 2936, 1666, 1596, 1581, 1505, 1473, 1423, 1314,
1
–
1
H), 6.46 (dd, J = 7.7, 1.9 Hz, 3 H), 3.61 (t, J = 5.8 Hz, 6 H), 2.87 (t,
J = 5.8 Hz, 6 H).
MS (EI): m/z = 506 ([M]+).
267, 1059, 989, 838, 751, 517 cm .
1
H NMR (DMSO-d , 400 MHz): d = 10.22 (s, 3 H), 7.65 (d, J = 8.8
6
Hz, 6 H), 7.20 (dd, J = 8.2, 2.2 Hz, 3 H), 7.17 (t, J = 8.2 Hz, 3 H),
7
.10 (dd, J = 8.2, 2.2 Hz, 3 H), 6.99 (d, J = 8.8 Hz, 6 H), 3.86 (s, 9
Anal. Calcd for C H N O : C, 64.02; H, 5.97; N, 11.06. Found: C,
63.89; H, 5.87; N, 10.77.
2
7
30
4
6
H), 3.81 (s, 9 H).
1
3
C NMR (DMSO-d , 100 MHz): d = 164.8 (C), 152.9 (C), 146.3
6
X-ray Structural Analysis of 3
Formula: C H N O , M = 506.55, red crystal 0.30 × 0.20 × 0.15
(
(
C), 143.5 (C), 134.5 (C), 131.8 (C), 124.6 (CH), 124.1 (CH), 121.3
CH), 120.6 (CH), 115.1 (CH), 61.6 (CH ), 56.6 (CH ).
27 30
4
6
3
3
mm, a = 10.553(1), b = 12.018(1), c = 20.042(1) Å, b = 90.70(1),
+
MS (EI): m/z = 782 ([M ]).
3
–3
–1
V = 2541.7(3) Å , r = 1.324 g cm , m = 0.95 cm , no absorption
calc
Anal. Calcd for C H N O ·2H O: C, 66.00; H, 5.66; N, 6.84.
correction (0.972 £ T £ 0.986), Z = 4, monoclinic, space group
4
5
42
4
9
2
Found: C, 66.18; H, 5.67; N, 7.51.
P2 /n (No. 14), l = 0.71073 Å, T = 198 K, w and j scans, 9833 re-
1
–1
flections collected (±h, ±k, ±l), [(sin q)/l] = 0.66 Å , 6047 indepen-
dent (Rint = 0.032) and 3659 observed reflections [I ≥ 2 s(I)], 352
refined parameters, R1 = 0.055, wR2 = 0.111, max. residual elec-
N,N¢,N¢¢-(Nitrilotri-4,1-phenylene)tris(2,3-dihydroxybenz-
amide) (5)
The protected ligand 8 (250 mg, 0.32 mmol) was dissolved in
CH Cl (20 mL) and cooled in an ice bath. BBr (0.5 ml, 4.80 mmol)
was added and the mixture was warmed up to r.t. After 24 h, MeOH
was added, and the solvent was removed in vacuum. The residue
was dissolved in EtOAc and washed with H O. After drying
–
3
tron density 0.19 (–0.16) e Å , hydrogens at nitrogen and oxygen
atoms from difference Fourier calculations and refined free, others
calculated and refined as riding atoms.
2
2
3
Data set was collected with Nonius KappaCCD diffractometer,
equipped with a rotating anode generator Nonius FR591. Programs
used: data collection COLLECT (Nonius B.V., 1998), data reduc-
2
(
MgSO ), the solvent was removed again to obtain 212 mg (95%)
of 5 as a brown solid; mp 195 °C (dec.); R = 0.31 (CH Cl –MeOH,
4
17
18
f
2
2
tion Denzo-SMN, structure solution SHELXS-97, structure re-
finement SHELXL-97 (G.M. Sheldrick, Universität Göttingen,
1997), graphics SCHAKAL (E. Keller, Universität Freiburg,
2
0:1).
IR (KBr): 1644, 1600, 1530, 1505, 1460, 1320, 1268, 1231, 831,
–1
19
7
39, 520 cm .
1997).
Synthesis 2004, No. 12, 1977–1982 © Thieme Stuttgart · New York

PAPER
Triscatechol Derivatives
1981
N,N¢,N¢¢-Tri(2,3-dihydroxybenzylidene)-4,4¢,4¢¢-(1,3,5-benzene-
triyltri-2,1-ethynediyl)trisbenzeneamine (11)
(10 equiv) with cooling in an ice bath. After overnight at r.t., the
mixture was quenched with MeOH, evacuated in vacuum and the
Yield: 160 mg (86%); orange solid; mp 187 °C (dec.); R = 0.19
residue was dissolved in EtOAc. After washing with H O, the or-
f
2
(
CH Cl –MeOH, 15:1).
ganic phase was dried (MgSO ) and the solvent was removed in
2
2
4
vacuum.
IR (KBr): 3437, 1620, 1574, 1503, 1460, 1365, 1272, 1207, 1070,
–
1
1
029, 873, 837, 780, 732, 568 cm .
1
,3,5-Tris(2,3-dihydroxyphenyl)benzene (17)
1
H NMR (DMSO-d , 400 MHz): d = 12.93 (br, 3 H), 9.29 (br, 3 H),
6
Yield: 144 mg (97%); yellow solid; mp 178 °C (dec.); R = 0.35
f
8
.98 (s, 3 H), 7.81 (s, 3 H), 7.71 (d, J = 8.5 Hz, 6 H), 7.52 (d, J = 8.5
(
CH Cl –MeOH, 20:1).
2 2
Hz, 6 H), 7.14 (dd, J = 7.9, 1.5 Hz, 3 H), 6.98 (dd, J = 7.9, 1.5 Hz,
IR (KBr): 3518, 1651, 1622, 1587, 1474, 1415, 1354, 1324, 1278,
3
H), 6.82 (t, J = 7.9 Hz, 3 H).
–
1
1
205, 1157, 1103, 1069, 962, 896, 836, 783, 738 cm .
1
3
C NMR (DMSO-d , 100 MHz): d = 164.9 (CH), 149.8 (C), 148.8
6
1
H NMR (DMSO-d , 400 MHz): d = 9.48 (br, 3 H), 8.29 (br, 3 H),
6
(
(
C), 146.1 (C), 133.3 (CH), 124.2 (C), 123.4 (C), 123.1 (CH), 122.4
C), 119.9 (CH), 119.8 (CH), 119.4 (CH), 114.1 (CH), 91.3 (C),
7
.62 (s, 3 H), 6.81 (m, 6 H), 6.72 (t, J = 7.7 Hz, 3H).
1
3
8
8.7 (C).
C NMR (DMSO-d , 100 MHz): d = 146.1 (C), 143.0 (C), 138.2
6
MS (EI): m/z = 783 ([M]+).
(C), 129.2 (C), 128.6 (CH), 121.2 (CH), 119.7 (CH), 114.7 (CH).
MS (EI): m/z = 402 ([M]+).
Anal. Calcd for C H N O : C, 78.15; H, 4.24; N, 5.36. Found: C,
5
1
33
3
6
7
7.72; H, 4.58; N, 5.11.
Anal. Calcd for C H O ·2 H O: C, 65.75; H, 5.06. Found: C,
2
4
18
6
2
6
5.75; H, 4.76.
Protected Triscatechol Aryl Derivatives 15,16; General Proce-
dure
The starting tribromoaryl derivative (ca. 0.7 mmol) and Pd(PPh3)4
5¢¢-(2¢,3¢-Dihydroxy-4-biphenylyl)-2,2¢¢¢¢,5,5¢¢¢¢-tetrahydroxy-
1,1¢:4¢,1¢¢:3¢¢,1¢¢¢:4¢¢¢,1¢¢¢¢-quinquephenyl (18)
(0.1 mmol) were dissolved in toluene (25 mL) under argon. A mix-
Yield: 259 mg (98%); green solid; mp 205 °C (dec.); R = 0.25
f
ture of 2 M aq Na CO (3.5 mL) and 2,3-dimethoxyphenylboronic
(CH Cl –MeOH, 20:1).
2
3
2
2
acid (12; 3.21 equiv) were added in several portions. The yellow so-
lution was refluxed overnight and after cooling to r.t., was washed
with aq Na CO (2 ×). The organic phase was dried (MgSO ) and
IR (KBr): 3438, 1590, 1519, 1469, 1386, 1359, 1328, 1300, 1266,
1
5
1
235, 1209, 1157, 1120, 1069, 1015, 893, 830, 781, 731, 679, 591,
34 cm .
2
3
4
–1
the solvent was removed in vacuum.
H NMR (CD OD, 400 MHz): d = 7.88 (s, 3 H), 7.77 (d, J = 8.4 Hz,
3
6
H), 7.71 (d, J = 8.4 Hz, 6 H), 6.85 (dd, J = 8.0, 1.9 Hz, 3 H), 6.81
1
,3,5-Tris(2,3-dimethoxyphenyl)benzene (15)
(
dd, J = 8.0, 1.9 Hz, 3 H), 6.76 (t, J = 8.0 Hz, 3 H).
Yield: 235 mg (71%); grey solid; mp 188 °C (dec.).
1
3
C NMR (CD OD, 100 MHz): d = 145.3 (C), 142.4 (C), 142.1 (C),
IR (KBr): 3431, 2969, 2935, 1575, 1469, 1408, 1305, 1264, 1227,
3
–
1
139.1 (C), 138.1 (C), 132.4 (C), 129.5 (CH), 126.4 (CH), 124.1
CH), 120.9 (CH), 119.3 (CH), 113.8 (CH).
1
170, 1122, 1085, 1059, 1003, 786, 748, 721 cm .
(
1
H NMR (CDCl , 400 MHz): d = 7.75 (s, 3 H), 7.11 (t, J = 8.0 Hz,
3
MS (EI): m/z = 630 ([M]+).
3
H), 7.06 (dd, J = 8.0, 1.9 Hz, 3 H), 6.93 (dd, J = 8.0, 1.9 Hz, 3 H),
3
.92 (s, 9 H), 3.69 (s, 9 H).
Anal. Calcd for C H O ·2H O: C, 75.66; H, 4.79. Found: C, 75.38;
H, 4.82.
4
2
30
6
2
1
3
C NMR (CDCl , 100 MHz): d = 152.9 (C), 146.5 (C), 137.5 (C),
3
1
35.8 (C), 128.9 (CH), 123.8 (CH), 122.7 (CH), 111.4 (CH), 60.6
(
CH ), 55.9 (CH ).
3 3
Acknowledgment
MS (EI): m/z = 486 ([M]+).
Financial support by the Deutsche Forschungsgemeinschaft (SPP
118) is gratefully acknowledged.
Anal. Calcd for C H O ·H O: C, 71.41; H, 6.39. Found: C, 71.58;
H, 6.35.
30
30
6
2
1
5
1
¢¢-(2¢,3¢-Dimethoxy-4-biphenylyl)-2,2¢¢¢¢,5,5¢¢¢¢-tetramethoxy-
,1¢:4¢,1¢¢:3¢¢,1¢¢¢:4¢¢¢,1¢¢¢¢-quinquephenyl (16)
References
Yield: 430 mg (88%); grey solid; mp 218 °C (dec.).
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IR (KBr): 2934, 2830, 1579, 1514, 1470, 1426, 1388, 1314, 1261,
1
(
2) (a) Saalfrank, R. W.; Bernt, I. Curr. Opin. Solid State Mater.
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–
1
229, 1117, 1086, 1031, 1010, 835, 789, 747 cm .
1
H NMR (CDCl , 400 MHz): d = 7.93 (s, 3 H), 7.80 (d, J = 8.5 Hz,
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3
6
H), 7.70 (d, J = 8.5 Hz, 6 H), 7.15 (t, J = 7.8 Hz, 3 H), 7.04 (dd,
J = 7.8, 1.7 Hz, 3 H), 6.95 (dd, J = 7.8, 1.7 Hz, 3 H), 3.93 (s, 9 H),
3
.66 (s, 9 H).
1
3
(3) Albrecht, M.; Janser, I.; Meyer, S.; Weis, P.; Fröhlich, R.
C NMR (CDCl , 100 MHz): d = 153.0 (C), 146.5 (C), 141.8 (C),
3
Chem. Commun. 2003, 2854.
1
(
39.6 (C), 137.3 (C), 135.3 (C), 129.6 (CH), 126.8 (CH), 124.8
CH), 123.9 (CH), 122.4 (CH), 111.5 (CH), 60.6 (CH ), 55.9 (CH ).
(
(
4) Albrecht, M.; Janser, I.; Runsink, J.; Raabe, G.; Fröhlich, R.
004, submitted for publication.
5) Albrecht, M.; Janser, I.; Kamptmann, S.; Weis, P.;
3 3
2
MS (EI): m/z = 714 ([M]+).
Anal. Calcd for C H O ·H O: C 78.67, H 6.05; found: C 78.18, H
Wibbeling, B.; Fröhlich, R. Dalton Trans. 2004, 37.
48
42
6
2
5
.92.
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Deprotection of the Catechol Aryl Derivatives 15 and 16; Gen-
eral Procedure
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Chem. 1999, 111, 3671.
The ether-protected catechol aryls 15, 16 (1 equiv, ca. 0.4 mmol)
were dissolved in CH Cl (20 mL). To this solution was added BBr
3
2
2
Synthesis 2004, No. 12, 1977–1982 © Thieme Stuttgart · New York

1
982
M. Albrecht et al.
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(
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Synthesis 2004, No. 12, 1977–1982 © Thieme Stuttgart · New York