Preparation of a highly alkyl-substituted dicatechol ligand and its dinuclear titanium(IV) complex

Article abstract of DOI:10.1055/s-2001-18448

The highly alkyl-substituted dicatechol derivative 10-H₄ is prepared with a triphenyl phosphite activated amide bond formation and a trifluoroacetic acid promoted dioxolane cleavage as the crucial steps in the reaction sequence. Compound 10-H

Full text of DOI:10.1055/s-2001-18448

2234
PAPER
Preparation of a Highly Alkyl-Substituted Dicatechol Ligand and its Dinuclear
Titanium(IV) Complex
H
ighly Alkyl Substitut
a
ed Dicatech
r
ol Ligan
k
d
us Albrecht,* Matthias Schneider
Institut für Organische Chemie, Universität Karlsruhe, Richard-Willstätter-Allee, 76131 Karlsruhe, Germany
E-mail: albrecht@ochhades.chemie.uni-karlsruhe.de
Received 31 July 2001; revised 31 August 2001
Abstract: The highly alkyl-substituted dicatechol derivative 10-H4
is prepared with a triphenyl phosphite activated amide bond forma-
tion and a trifluoroacetic acid promoted dioxolane cleavage as the
crucial steps in the reaction sequence. Compound 10-H4 forms an
triple-stranded helicate-type titanium(IV) complex K4[(10)3Ti2]
with a polar central dinuclear complex unit and a nonpolar periph-
ery.
Key words: amides, complexes, helical structures, ligands, su-
pramolecular chemistry
Triple-stranded helicates or meso-helicates are formed in
metal-directed self-assembly processes by simple mixing
of linear oligodonor ligands with appropriate metal
ions.1,2 For example, dinuclear helicate-type complexes
can be formed from a series of dicatechol derivatives with
different spacers and metals like Fe(III), Al(III), Ga(III),
Ti(IV), or V(IV).2,3 The obtained coordination com-
pounds possess a cylindrical shape and a relatively high
negative charge (Figure 1a). The polar character of those
species makes them highly soluble in solvents like water,
methanol, acetone, or DMSO.
The attachment of non-polar side chains in the periphery
of the ligand should lead to triple-stranded complexes
with a charged, polar cylindrical core which is embedded
in a non-polar shell (Figure, b). Upon crystallization, the
molecules should be able to staple in columns with attrac-
Figure Schematic representation of the metal directed self-assem-
tive intermolecular interactions between polar and be-
tween non-polar parts of the helicate-type complexes.
bly of a triple-stranded helicate (a) and of a highly alkyl-substituted
helicate which possesses the potential to form columns in the solid
state (b).
Ziessel and coworkers described the synthesis of a highly
alkyl-substituted bis(iminopyridine) ligand which forms a
double-stranded helicate with copper(I) ions. The com-
plex shows two phase transitions at 25 °C and 181 °C due
to the formation of a columnar mesophase.4
As nonpolar substituent we choose the 1,2,3-tris(hexade-
cyloxy)phenyl moiety, which should be attached to the
ligand unit by amide coupling. The trisalkoxy-substituted
aniline derivative 4 is prepared in analogy to a literature
procedure starting from 1,2,3-trihydroxybenzene (1).6 In
the first step, three hexadecyl chains are introduced by
Williamson ether synthesis and the aryl ether 2 is isolated
in 86%. Nitration of 2 with concentrated nitric acid on sil-
ica gel affords derivative 3 in 86% yield which is reduced
with hydrogen in the presence of Adams catalyst (PtO2) to
obtain the desired aniline derivative 4 in 71% (Scheme 1).
We already described the preparation of a tetra(decyl)-
substituted ethylene-bridged di(8-hydroxyquinoline)
ligand, which due to its substitution pattern forms a
“spherical” helicate with gallium(III) ions in the presence
of alkali metal cations.5 Herein we describe the prepara-
tion of a dicatechol derivative and the formation of its ti-
tanium(IV) complex. Due to the position of the attached
alkyl chains, the coordination compound should possess a
shape as depicted in the Figure, b.
The protected precursor of the dicatechol ligand unit 8 is
synthesized following the route which we recently devel-
oped for the preparation of ether-linked dicatechol ligands
and which is outlined in Scheme 2. Thus, gallic acid me-
thyl ester 5 is protected by reaction with diphenyldichlo-
Synthesis 2001, No. 15, 12 11 2001. Article Identifier:
1437-210X,E;2001,0,15,2234,2238,ftx,en;Z09201SS.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0039-7881

PAPER
Highly Alkyl Substituted Dicatechol Ligand
2235
The cleavage of benzophenone ketals (like in 9) is usually
performed by mild acid hydrolysis or by hydrogenolytic
cleavage.11 However, in the case of 9 we were not able to
remove the diphenylmethyl group neither by refluxing the
compound in acetic acid nor by hydrogenation in the pres-
ence of palladium on charcoal or platinum dioxide. The
latter reaction did not proceed even at elevated pressure
(50 bar). However, refluxing the diketal 9 in trifluoroace-
tic acid (TFA) overnight resulted in the liberation of the
desired ligand 10-H4 (Scheme 3). The compound is puri-
fied by column chromatography (silica gel, methanol–
dichloromethane) and is obtained as a beige waxy solid in
61% yield.
Scheme 1
When we took the 1H NMR spectrum of 10-H4 in CDCl3,
we were surprised to observe only broad undefined sig-
nals. This was attributed to an aggregation of the mole-
cules which possess highly polar and two highly nonpolar
moieties. However, addition of a few drops of methanol-
d4 effected the break up of the aggregates and a defined
NMR spectrum could be obtained, which showed the sig-
nals of the aromatic protons of 10-H4 at = 6.93 (br s, 2
H), 6.86 (br s, 2 H), 6.79 (s, 4 H), the signals of the spacer
at = 4.07 (4 H) and 2.11 (br, 2 H) and the resonances of
the hexadecyl substituents at = 3.76 (t, J = 6.7 Hz, 8 H),
3.73 (t, J = 6.7 Hz, 4 H), 1.57 (m, 12 H), 1.26 (m, 12 H),
1.06 (br, 144 H), 0.68 (t, J = 6.7 Hz, 18 H).
romethane (92%) and the resulting derivative 6 is
submitted to a Williamson ether synthesis with 1,3-di-
iodopropane (61%).7 The esters of 7 are hydrolyzed by re-
action with KOH in ethanol–dioxane and the diacid 8 is
obtained in 66% yield (Scheme 2).
Ligand 10-H4 forms a triple-stranded dinuclear titani-
um(IV) complex K4[(10)3Ti2] with titanium(IV) ions on
stirring with titanoyl bis-acetylacetonate in the presence
of potassium carbonate in methanol overnight
(Scheme 4). The dinuclear complex K4[(10)3Ti2] precipi-
tates out and is characterized by elemental analysis and
NMR spectroscopy. Related dinuclear complexes without
alkyl substituents have been described earlier.7
K4[(10)3Ti2] is insoluble in methanol, but due to the alkyl
substituents readily dissolves in chloroform. However,
1
again only broad signals are observed in the H NMR
spectrum in CDCl3 and again the spectrum gets resolved
by adding a few drops of methanol-d4. The resonances of
the aromatic protons are observed at = 6.84 and 6.78 as
broad signals, the spacer protons are found at = 3.62
(overlapped with the water peak) and 1.96 and the signals
of the alkyl units are observed at = 3.83 (24 H, OCH2),
3.79 (12 H, OCH2), 1.68 (24 H), 1.62 (12 H), 1.33 (42 H),
1.14 (432 H), 0.76 (54 H, CH3). The compound exhibits
the typical orange brown color12 of a titanium(IV) triscat-
echolate complex ( max = 222, 228, 305 nm).
Scheme 2
The formation of the protected ligand 9 by coupling of the
aniline derivative 4 (2 equiv) with the diacid 8 and the fi-
nal deprotection step to obtain 10-H4 both turned out to be
surprisingly difficult.
For the amide coupling of 8 and 4, the diacid 8 had to be
activated first. The use of classical peptide coupling
agents like N-hydroxysuccinimide/dicyclohexylcarbo-
diimide8 or hydroxybenzotriazole9 failed, as well as the
preparation of the corresponding acid chloride followed
by addition of the aniline derivative 4. Finally we were
able to achieve the amide coupling by activation of the di-
acid 8 with triphenyl phosphite10 followed by reaction
with 4 in 28% yield. The protected ligand 9 is obtained as
a white solid after column chromatography.
In this paper we have presented the synthesis of an ether-
linked dicatechol ligand 10-H4 which bears highly alkyl-
substituted side chains. An amide coupling to attach the
side-chains and the deprotection of the ligand precursor
turned out to be unexpectedly difficult. This is addressed
to “solubility problems” of the corresponding alkyl-sub-
stituted derivatives with an internal polar group. Howev-
er, these problems were solved by using triphenyl
phosphite as an activator for the amide coupling and pure
trifluoroacetic acid for the cleavage of the benzophenone
ketals. The ligand 10-H4 forms a dinuclear titanium(IV)
Synthesis 2001, No. 15, 2234–2238 ISSN 0039-7881 © Thieme Stuttgart · New York

2236
M. Albrecht, M. Schneider
PAPER
Scheme 3
Scheme 4
1H NMR and 13C NMR spectra were recorded on a Bruker DRX 500
spectrometer using DEPT techniques for the assignment of the mul-
tiplicity of carbon atoms. FT-IR spectra were recorded by diffuse
reflection (KBr) on a Bruker IFS spectrometer. UV-Vis spectra
were recorded on a Perkin Elmer Lambda 2 spectrometer. Mass
spectra (EI, 70 eV) were taken on a Finnigan MAT 90 mass spec-
trometer. Elemental analyses were obtained with a Heraeus CHN-
O-Rapid analyzer. Solvents were purified by standard methods.
Melting points: Büchi B-540 (uncorrected). Air sensitive com-
pounds were prepared and handled under Ar using Schlenk tech-
niques. Compound 7 was prepared as described earlier.7
complex K4[(10)3Ti2] with an internal polar complex unit
and nonpolar side groups. Unfortunately we were not able
to observe mesophases. The complex does not melt below
300 °C. This might be due to hydrogen bonding of the
amide groups which might stabilize the solid state pack-
ing. We are now working on the synthesis of related
ligands with multiple hydrocarbon chains directly at-
tached to the ligand units.
Synthesis 2001, No. 15, 2234–2238 ISSN 0039-7881 © Thieme Stuttgart · New York

PAPER
Highly Alkyl Substituted Dicatechol Ligand
2237
3,4,5-Tris(hexadecyloxy)benzene (2)
IR (KBr): 3413, 3335, 3206, 2918, 2850, 1597, 1505, 1467, 1395,
1241, 1115, 814, 721 cm–1.
1,2,3-Trihydroxybenzene (1; 1.00 g, 7.94 mmol), K2CO3 (5.24 g,
37.7 mmol) and 1-bromo hexadecane (8.00 g, 26.2 mmol) were dis-
solved in DMF (50 mL). The mixture was stirred at 80 °C for 6 h
and then additional 1-bromohexadecane (2.70 g, 8.74 mmol) was
added. After heating overnight and cooling to r.t., the mixture was
poured onto ice. The precipitate was isolated by filtration and re-
crystallized from acetone; yield: 5.4 g (86%); white solid, mp
70 °C.
1H NMR (CDCl3): = 6.90 (t, J = 8.3 Hz, 1 H), 6.53 (d, J = 8.3 Hz,
2 H), 3.96 (t, J = 6.5 Hz, 4 H), 3.94 (t, J = 6.7 Hz, 2 H), 1.83 (m, 6
H), 1.50 (m, 6 H), 1.25 (m, 72 H), 0.88 (t, J = 6.7 Hz, 9 H).
13C NMR (CDCl3): = 153.5 (C), 138.5 (C), 123.1 (CH), 106.8
(CH), 73.4 (CH2), 69.1 (CH2), 64.0 (CH2), 51.3 (CH2), 34.1 (CH2),
32.9 (CH2), 32.0 (CH2), 29.8 (CH2), 29.7 (CH2), 29.5 (CH2), 29.4
(CH2), 29.2 (CH2), 28.8 (CH2), 28.2 (CH2), 26.3 (CH2), 26.2 (CH2),
25.8 (CH2), 22.8 (CH2), 22.7 (CH2), 14.2 (CH3).
UV-Vis (MeOH): max = 191, 209, 270 nm.
MS (EI, 70 eV): m/z = 814 ([M]+, 100%).
HRMS (EI, 70 eV): m/z calcd for C54H103O3N: 813.7938. Found:
813.7985.
Anal. Calcd for C54H103O3N: C, 79.64; H, 12.75; N, 1.72. Found: C,
79.61; H, 12.21; N, 1.82.
7-{3-[(6-Carboxy-2,2-diphenyl-1,3-benzodioxol-4-yl)oxy]-
propoxy}-2,2-diphenyl-1,3-benzodioxole-5-carboxylic Acid (8)
KOH (2.55 g, 45.4mmol) was added to a solution of 77 (2.94 g, 4.00
mmol) in dioxane (70 mL) and EtOH (70 mL). The mixture was re-
fluxed for 2.5 h and the solvent was removed in vacuum. The resi-
due was dissolved in H2O and the pH was adjusted to 8 by adding
concd HCl. The resulting precipitate was isolated and washed with
H2O; yield: 2.83 g (quant.); white solid.
1H NMR (DMSO-d6): = 7.50 (m, 8 H), 7.39 (m, 12 H), 7.30 (d,
J = 1.4 Hz, 2 H), 7.20 (d, J = 1.4 Hz, 2 H), 4.33 (t, J = 6.3 Hz, 4 H),
2.20 (m, 2 H).
IR (KBr): 3370, 2916, 2849, 1604, 1471, 1296, 1259, 1224, 1119,
1106, 717 cm–1.
UV-Vis (CHCl3): max = 227, 369 nm.
MS (EI, 70 eV): m/z = 799 ([M]+, 100%).
13C NMR (DMSO-d6): = 166.5 (C), 147.6 (C), 141.9 (C), 139.1
(C), 129.5 (CH), 128.6 (CH), 125.8 (CH), 125.1 (C), 118.3 (C),
112.4 (CH), 103.8 (CH), 66.5 (CH2), 30.7 (CH2).
Anal. Calcd for C54H102O3 0.5CH2Cl2: C, 77.76; H, 12.88. Found:
C, 77.76; H, 11.88.
IR (KBr): 3436, 3064, 1684, 1630, 1507, 1436, 1325, 1273, 1208,
1118, 1044, 1019, 775, 762, 701 cm–1.
3,4,5-Tris(hexadecyloxy)nitrobenzene (3)
To a suspension of silica gel (2 g) in CH2Cl2 (20 mL) were added
first concd HNO3 (20 mL) and then a solution of tris(hexadecy-
loxy)benzene (2; 4.00 g, 5.01 mmol) in CH2Cl2 (30 mL). The mix-
ture was stirred for 15 min and the silica gel was removed by
filtration. The organic phase was washed with H2O and the product
was precipitated by addition of MeOH; yield: 3.64 g (86%); white
solid; mp 70 °C.
UV-Vis (MeOH): max = 270 nm.
Anal. Calcd for C43H32O10: C, 72.87; H, 4.45. Found: C, 72.27; H,
4.67.
7-{3-[(2,2-Diphenyl-6-{[3,4,5-tris(hexadecyloxyanilino]-car-
bonyl}-1,3-benzodioxol-4-yl)oxy]propoxy}-2,2-diphenyl-N-
[3,4,5-tris(hexadecyloxy)phenyl]-1,3-benzodioxole-5-carboxylic
Acid (9)
1H NMR (CDCl3): = 7.47 (s, 2 H), 4.05 (m, 6 H), 1.84 (m, 4 H),
1.75 (m, 2 H), 1.48 (m, 6 H), 1.26 (br, 72 H), 0.88 (t, J = 6.9 Hz, 9
To a solution of 3,4,5-tris(hexadecyloxy)aniline (4; 452 mg, 0.56
mmol) and 8 (197 mg, 0.28 mmol) in pyridine (20 mL) was added
triphenyl phosphite (146 L, 0.56 mmol). After refluxing for 48 h,
the mixture was allowed to cool to r.t. and the crude product was
precipitated by the addition of EtOH. Purification was done by
chromatography (silica gel, CH2Cl2); yield: 175 mg (28%); white
solid; mp 91 °C.
1H NMR (CDCl3): = 7.61 (s, 2 H), 7.55 (m, 8 H), 7.33 (m, 12 H),
7.14 (d, J = 1.5 Hz, 2 H), 7.00 (d, J = 1.5 Hz, 2 H), 6.84 (s, 4 H),
4.39 (t, J = 6.0 Hz, 4 H), 3.91 (t, J = 6.5 Hz, 8 H), 3.90 (t, J = 6.6
Hz, 4 H), 2.28 (quin, J = 6.0 Hz, 2 H), 1.75 (m, 12 H), 1.44 (m, 12
H), 1.27 (m, 144 H), 0.88 (t, J = 7.0 Hz, 18 H).
13C NMR (CDCl3): = 164.8 (C), 153.2 (C), 148.8 (C), 142.6 (C),
139.5 (C), 138.4 (C), 135.0 (C), 133.5 (C), 129.5 (C), 129.4 (C),
128.3 (C), 126.3 (CH), 118.5 (C), 110. 0 (CH), 101.2 (CH), 99.1
(CH), 73.5 (CH2), 69.1 (CH2), 66.4 (CH2), 60.4 (CH2), 32.0 (CH2),
30.4 (CH2), 29.8 (CH2), 29.7 (CH2), 29.5 (CH2), 29.4 (CH2), 26.2
(CH2), 26.1 (CH2), 22.7 (CH2), 14.1 (CH3).
H).
13C NMR (CDCl3): = 152.7 (C), 143.8 (C), 143.2 (C), 102.2 (CH),
73.8 (CH2), 69.5 (CH2), 32.0 (CH2), 30.3 (CH2), 29.7 (CH2), 29.6
(CH2), 29.5 (CH2), 29.4 (CH2), 29.1 (CH2), 26.0 (CH2), 22.7 (CH2),
14.1 (CH3).
IR (KBr): 3433, 2955, 2917, 2849, 1512, 1469, 1346, 1123, 720
cm–1.
UV-Vis (CHCl3): max = 227, 333 nm.
MS (EI, 70 eV): m/z = 844 ([M]+, 82 %).
HRMS (EI, 70 eV): m/z Calcd for C54H101O5N: 843.7680. Found:
843.7642.
Anal. Calcd for C54H101O5N 0.5H2O: C, 76.00; H, 12.05; N: 1.64.
Found: C, 75.85; H, 11.64; N, 1.63.
3,4,5-Tris(hexadecyloxy)aniline (4)
A solution of 3 (1.03 g, 1.23 mmol) in CH2Cl2 (150 mL) was stirred
with PtO2 H2O (150 mg) under an atmosphere of H2. The reaction
was followed by TLC (CH2Cl2). After 36 h, the catalyst was filtered,
the solvent was removed in vacuum and the crude product was pu-
rified by recrystallization from acetone; yield: 711 mg (71%); white
solid; mp 54 °C.
1H NMR (CDCl3): = 6.03 (s, 2 H), 3.91 (t, J = 6.5 Hz, 4 H), 3.85
(t, J = 6,6 Hz, 2 H), 1.77 (m, 4 H), 1.71 (m, 2 H), 1.45 (m, 6 H), 1.26
(br, 72 H), 0.88 (t, J = 6.9 Hz, 9 H).
IR (KBr): 3305, 2919, 2851, 1604, 1504, 1468, 1433, 1326, 1209,
1119, 1046, 1021, 722, 699 cm–1.
UV-Vis (CHCl3): max = 222, 227, 296 nm.
Anal. Calcd for C151H234O14N2: C, 78.85; H, 10.18; N, 1.22. Found:
C, 78.53; H, 10.02; N, 1.02.
3-[3-(2,3-Dihydroxy-5-{[3,4,5-tris(hexadecyloxy)anilino]-car-
bonyl}phenoxy)propoxy]-4,5-dihydroxyy-N-[3,4,5-tris(hexa-
decyloxy)phenyl]benzamide (10-H4)
Compound 9 (175 mg, 0.08 mmol) was refluxed overnight in triflu-
oroacetic acid (20 mL). The solvent was removed in vacuum and the
13C NMR (CDCl3): = 153.8 (C), 139.5 (C), 132.3 (C), 95.6 (CH),
73.6 (CH2), 69.1 (CH2), 31.9 (CH2), 30.3 (CH2), 29.7 (CH2), 29.4
(CH2), 26.2 (CH2), 26.1 (CH2),. 22.7 (CH2), 14.1 (CH3).
Synthesis 2001, No. 15, 2234–2238 ISSN 0039-7881 © Thieme Stuttgart · New York

2238
M. Albrecht, M. Schneider
PAPER
residue was purified by chromatography (silica gel, MeOH–
CH2Cl2); yield: 96 mg (61%); beige waxy solid.
1H NMR (CDCl3–CD3OD): = 6.93 (br s, 2 H), 6.86 (br s, 2 H),
6.79 (s, 4 H), 4.07 (4 H, hidden under the signal of H2O), 3.76 (t,
J = 6.7 Hz, 8 H), 3.73 (t, J = 6.7 Hz, 4 H), 2.11 (br, 2 H), 1.57 (m,
12 H), 1.26 (m, 12 H), 1.06 (br, 144 H), 0.68 (t, J = 6.7 Hz, 18 H).
Acknowledgement
This work was supported by the Fonds der Chemischen Industrie
and the Deutsche Forschungsgemeinschaft.
References
13C NMR (CDCl3–MeOH): = 167.1 (C), 153.3 (C), 147.2 (C),
145.0 (C), 138.0 (C), 134.7 (C), 134.6 (C), 125.7 (C), 108.7 (CH),
104.9 (CH), 100.0 (CH), 74.0 (CH2), 69.3 (CH2), 66.5 (CH2), 32.2
(CH2), 30.5 (CH2), 30.0 (CH2), 29.9 (CH2), 29.7 (CH2), 29.7 (CH2),
29.6 (CH2), 29.3 (CH2), 26.4 (CH2), 26.1 (CH2), 23.8 (CH2), 22.9
(CH2), 14.2 (CH3).
(1) (a) Lehn, J.-M. Chem. Biol. (Introductory Issue) 1994, xviii.
(b) Piguet, C.; Bernardinelli, G.; Hopfgartner, G. Chem. Rev.
1997, 97, 2005. (c) Piguet, C. J. Inclusion Phenom.,
Macrocyclic Chem. 1999, 34, 361. (d) Albrecht, M. Chem.–
Eur. J. 2000, 6, 3485. (e) Williams, A. F. Chimia 2000, 54,
585.
IR (KBr): 3371, 2920, 2851, 1602, 1506, 1468, 1424, 1344, 1227,
1118, 721 cm–1.
(2) Albrecht, M. Chem. Soc. Rev. 1998, 27, 281.
(3) (a) Albrecht, M.; Kotila, S. Angew. Chem., Int. Ed. Engl.
1995, 34, 2134. (b) Enemark, E. J.; Stack, T. D. P. Angew.
Chem., Int. Ed. Engl. 1995, 34, 996. (c) Kersting, B.;
Meyer, M.; Powers, R. E.; Raymond, K. N. J. Am. Chem.
Soc. 1996, 118, 7221. (d) Sun, X.; Darren, W. J.; Caulder,
D.; Powers, R. E.; Raymond, K. N.; Wong, E. N. Angew.
Chem., Int. Ed. 1999, 38, 1303.
(4) El-ghayouy, A.; Douce, L.; Skoulios, A.; Ziessel, R. Angew.
Chem. Int. Ed. 1998, 37, 2205.
(5) Albrecht, M.; Blau, O.; Zauner, J. Eur. J. Org. Chem. 1999,
3165.
UV (CHCl3): max = 227, 299 nm.
Anal. Calcd for C125H218N2O14 CH2Cl2: C, 73.53; H, 10.77; N, 1.36.
Found: C, 73.73; H, 10.41; N, 1.66.
K4[(10)3Ti2]; A Dinuclear Titanium(IV) Complex of 10-H4
A 0.11 M aq K2CO3 solution (100 L) was added to a mixture of the
ligand 10-H4 (31.5 mg, 0.016 mmol) and titanoyl bis-acetylaceto-
nate (2.8 mg, 0.011 mmol) in MeOH (20 mL). The red mixture was
stirred overnight and the precipitated product was filtered and dried
in vacuum; yield: 34 mg (53%); orange-brown solid; mp >300 °C.
1H NMR (CDCl3–CD3OD): = 6.87 (br, 12 H), 6.84 (br, 12 H),
3.83 (m, 24 H), 3.79 (m, 12 H), 3.62 (12 H, hidden under the signal
of H2O), 1.91 (br, 6 H),1.68 (m, 24 H), 1.62 (m, 12 H), 1.33 (br, 42
H), 1.14 (br, 432 H), 0.76 (t, J = 6.9 Hz, 54 H).
(6) Percec, V.; Ahn, C.; Bera, T. K.; Ungar, G.; Yeardly, D. J. P.
Chem. Eur. J. 1999, 5, 1070.
(7) Albrecht, M.; Schneider, M. J. Prakt. Chem. 1999, 341, 657.
(8) Bergeron, R. J.; Kline, S. J.; Stolowich, N. J.; McGovern, K.
A.; Burton, P. S. J. Org. Chem. 1981, 46, 4524.
(9) Brettreich, M.; Hirsch, A. Synlett 1998, 1396.
(10) Kraft, A.; Osterod, F. J. Chem. Soc., Perkin Trans. 1 1998,
1019.
IR (KBr): 3408, 2922, 2852, 1602, 1504, 1487, 1468, 1429, 1339,
1113 cm–1.
UV-Vis (CHCl3): max = 222, 228, 305 nm.
(11) (a) Jurd, L. J. Am. Chem. Soc. 1959, 81, 4606. (b) Haslam,
E.; Haworth, R. D.; Mills, S. D.; Rogers, R. J.; Armitage, R.;
Searle, T. J. Chem. Soc. 1961, 1836.
(12) Albrecht, M.; Schneider, M.; Röttele, H. Chem. Ber. 1997,
130, 615.
Anal. Calcd for C375H642N6O42 10H2O: C, 71.05; H, 10.52; N, 1.33.
Found: C, 71.01; H, 10.52; N, 1.33.
Synthesis 2001, No. 15, 2234–2238 ISSN 0039-7881 © Thieme Stuttgart · New York