Fullerodendrons: Synthesis, electrochemistry and reduction in the electrospray source for mass spectrometry analysis

Article abstract of DOI:10.1039/b003345f

The synthesis of fullerene-functionalized dendritic branches (fullerodendrons) containing C₆₀ spheres at each branching unit has been carried out by a convergent approach using successive esterification and deprotection steps. The tert-butyl pr

Full text of DOI:10.1039/b003345f

View Online / Journal Homepage / Table of Contents for this issue
Fullerodendrons: synthesis, electrochemistry and reduction in the
electrospray source for mass spectrometry analysis
Delphine Felder,a Helene Nierengarten,b Jean-Paul Gisselbrecht,c Corinne Boudon,c
Emmanuelle Leize,b Jean-Francois Nicoud,a Maurice Gross,*c Alain Van Dorsselaer*b and
Jean-Francois Nierengarten*a
a Institut de Physique et Chimie des Materiaux de Strasbourg, Groupe des Materiaux Organiques,
Universite L ouis Pasteur and CNRS (UMR 7504), 23 rue du L oess, 67037, Strasbourg, France.
E-mail: niereng=ipcms.u-strasbg.fr
b L aboratoire de Spectrometrie de Masse Bio-Organique, Universite L ouis Pasteur and CNRS
(UMR 7509), 1 rue Blaise Pascal, 67000, Strasbourg, France.
E-mail: vandors=chimie.u-strasbg.fr
c L aboratoire dÏElectrochimie et de Chimie Physique du Corps Solide, Universite L ouis Pasteur
and CNRS (UMR 7512), 4 rue Blaise Pascal, 67008, Strasbourg, France.
E-mail: gross=chimie.u-strasbg.fr
Received (in Strasbourg, France) 25th April 2000, Accepted 29th May 2000
Published on the Web 18th July 2000
The synthesis of fullerene-functionalized dendritic branches (fullerodendrons) containing C spheres at each
60
branching unit has been carried out by a convergent approach using successive esteriÐcation and deprotection
steps. The tert-butyl protected fullerodendrons containing one, three or seven methanofullerene subunits can be
characterized by ESMS owing to their reduction in the electrospray source. The MS analysis of the reduced species
also conÐrmed that all the methanofullerene subunits in the fullerodendrons of highest generation behave as
independent redox centers, as shown by their electrochemical behavior.
The recent developments in the functionalization of fullerenes
allow the preparation of covalent fullerene derivatives with
increasing complexity.1 Since X-ray suitable crystals of suffi-
cient quality are often difficult to obtain with fullerene deriv-
atives, mass spectrometry (MS) and NMR spectroscopy
appear to be the most important tools for their structural
analysis. As far as MS is concerned, several ionization tech-
niques such as electron impact (EI),2 matrix-assisted laser
desorption/ionization (MALDI),3 or fast-atom bombardment
(FAB)4 have been used to characterize functionalized ful-
lerenes. Unfortunately, these techniques are not always well
induce ionization for MS analysis.10 As a matter of fact,
radical cations (positive mode) or radical anions (negative
mode) can be generated during the ES process owing to the
ability of the ES source to behave like an electrolysis cell.11
In this paper, we report in detail the synthesis of fullerene-
functionalized dendritic branches (fullerodendrons) containing
a C sphere at each branching unit12 and show that these
60
compounds can be characterized by ESMS on account of
their reduction in the electrospray source.
Results and discussion
Synthesis
adapted for C derivatives of high molecular weights. In
60
e†ect, with these methods, the MS analysis leads to fragmen-
tations and the molecular ions are not observed. This is due to
the fact that too much energy is deposited in the evaporation/
ionization process and/or that the matrices used are not well
adapted. Despite the problems and difficulties that may arise
with the increasing size of such molecules, encouraging per-
spectives are o†ered by the use of electrospray mass spectrom-
etry (ESMS)5 for their characterization. Indeed, under
carefully controlled experimental conditions, ESMS has the
ability to desolvate, without fragmentation, ions pre-existing
in solution. A wide variety of large biomolecules6 and coordi-
nation complexes,7 where the charge is respectively conferred
by protonation (deprotonation) and successive loss of counter-
ions, have been successfully characterized by ESMS. Unfor-
tunately, fullerene derivatives are generally uncharged in
solutions and therefore not suitable for ESMS analysis.
However, several strategies of ionization have been developed
to analyze uncharged compounds by ESMS, using ESMS-
active tags8 or reducing agents in solution.9 In the same way,
but without prior chemical or electrochemical treatment, we
The preparation of the fullerodendrons with a C group at
60
each branching unit was carried out by
a
convergent
approach,13 using successive esteriÐcation and deprotection
steps. The preparation of the key building block 1 is depicted
in Scheme 1. This diol containing one tert-butyl ester function
is the branching unit for the construction of the ful-
lerodendrons.
The mono-protection of 1,6-hexanediol was carried out by
treatment with Ag O and p-methoxybenzyl chloride (PMBCl)
2
according to the conditions reported by Bouzide and Sauve.14
Treatment of the resulting mono-protected derivative 2 with
CBr and PPh in dry THF at room temperature a†orded
4
3
bromide 3 in 79% yield. Reaction of 3 with 3,5-dihydroxy-
benzyl alcohol in DMF at 80 ¡C in the presence of K CO
2
3
yielded 4 in 52% yield. Subsequent reaction with 2,2-dimethyl-
1,3-dioxane-4,6-dione (MeldrumÏs acid)15 at 120 ¡C gave the
mono-ester 5 of malonic acid in 99% yield. N,N@-Dicyclo-
hexylcarbodiimide (DCC) mediated esteriÐcation of 5 with
tert-butyl 2-hydroxyacetate16 in CH Cl yielded malonate 6
in 91% yield. The functionalization of C is based on the
Bingel reaction.17 Nucleophilic addition of a stabilized a-
2
2
have already described the characterization of C and other
60
60
neutral species by ESMS, using their redox properties to
DOI: 10.1039/b003345f
New J. Chem., 2000, 24, 687È695
687
This journal is ( The Royal Society of Chemistry and the Centre National de la Recherche ScientiÐque 2000

View Online
Scheme 1 Preparation of methanofullerene 1 (5% overall yield from 1,6-hexanediol).
halocarbanion to the C core, followed by intramolecular
60
nucleophilic substitution, leads to clean cyclopropanation of
for the two alcohol functions in 7 was the key to this synthe-
sis. The deprotection conditions must not be acidic to preserve
the tert-butyl ester function and may not be basic to preserve
the other ester functions. Furthermore, the decomposition of
fullerene derivatives under reaction conditions using
Ñuoride19 prevents the use of silyl protecting groups. The
PMB protecting groups in 7 could be removed under neutral
C
. The a-halomalonate derivative was prepared in situ from
60
the reaction of the malonate with iodine.18 Treatment of C
60
with 6, iodine and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU)
in toluene at room temperature a†orded methanofullerene 7
in 30% yield. The choice of the appropriate protecting group
688
New J. Chem., 2000, 24, 687È695

View Online
the tert-butyl ester group with CF CO H21 gave carboxylic
conditions by treatment with 2,3-dichloro-5,6-dicyanobenzo-
quinone (DDQ) in CH Cl containing a small amount of
water20 at room temperature. All the ester functions remained
unchanged and key building block 1 was thus obtained in
good yield (84%).
Fullerene derivative 8 substituted with two long alkyl
chains (solubilizing groups) and a carboxylic function was
used as a peripheral subunit for the constructions of the den-
drons. Its preparation is depicted in Scheme 2.
3
2
acid 8 in 97% yield.
2
2
EsteriÐcation of acid 8 with diol 1 under conditions using
DCC, 1-hydroxybenzotriazole (BtOH) and DMAP a†orded
the tert-butyl-protected fullerodendron 13 in 70% yield
(Scheme 3). Selective hydrolysis of the tert-butyl ester under
acidic conditions a†orded acid 14 in 98% yield. Subsequent
reaction of 14 with the branching unit 1 in the presence of
DCC, BtOH and DMAP a†orded fullerodendron 15 (Scheme
4), which after treatment with CF CO H gave 16. The 1H and
Alcohol 9 was obtained in 90% yield by alkylation of 3,5-
dihydroxybenzyl alcohol with 1-bromooctane in DMF at
70 ¡C with K CO as base. Subsequent treatment with
3
2
13C NMR, MS, IR, UV/Vis and elemental analysis data were
consistent with the proposed molecular structures assigned to
the fullerodendrons of each generation.
2
3
MeldrumÏs acid at 120 ¡C a†orded the corresponding malonic
mono-ester 10 in 99% yield. Reaction of acid 10 with tert-
butyl 2-hydroxyacetate under esteriÐcation conditions using
DCC and 4-dimethylaminopyridine (DMAP) led to malonic
Electrochemistry
ester 11 in 93% yield. Treatment of C with 11 in the pres-
60
ence of iodine and DBU under Bingel conditions a†orded
The electrochemical properties of fullerodendrons 12, 13 and
15 have been investigated by cyclic voltammetry (CV) and by
methanofullerene 12 in 44% yield. Subsequent hydrolysis of
Scheme 2 Preparation of methanofullerene 8 (35% overall yield from 3,5-dihydroxybenzyl alcohol).
New J. Chem., 2000, 24, 687È695
689

View Online
Scheme 3 Preparation of fullerodendron 14.
steady state voltammetry (SSV) on a rotating disk electrode.
at [2.08 V vs. Fc/Fc` actually corresponds to the reduction
All experiments have been performed at room temperature in
of an electrogenerated species.24
CH Cl ] 0.1 M Bu NPF . The cyclic voltammograms of 12,
Methanofullerene 12 essentially retains the cathodic electro-
chemical pattern of the parent fullerene but the reduction
potentials are shifted to more negative values when compared
2
2
4
6
13, and 15 are shown in Fig. 1 and Table 1 summarizes the
redox potentials of the three compounds along those of C
.
60
Compound 12 shows the characteristic behavior previously
reported for methanofullerenes.22,23 By CV, up to three one-
electron reduction steps are seen [Fig. 1(a)] and no oxidation
could be observed at potentials below ]1 V vs. Fc/Fc`.
Whereas the Ðrst reduction is perfectly reversible, the second
reduction step shows the characteristics of an E.C. mechanism
at sweep rates lower than 1 V s~1 and is followed by a chemi-
cal reaction24 giving rise to the small amplitude signals seen in
Fig. 1(a). By SSV, a fourth well-resolved reduction step could
be seen. The Ðrst three reduction potentials determined by
SSV are similar to those obtained by CV. The additional wave
to those of C (Table 1). This is the classical behavior of most
60
fullerene derivatives, whose cyclic voltammograms are typi-
cally characterized by small shifts to more negative values as
the saturation of a double bond on the C surfaces causes a
60
partial loss of ““conjugationÏÏ.22,23
The electrochemical behavior of fullerodendron 13 in both
CV (Fig. 1) and SSV (Fig. 2) appears to be similar to that of
compound 12. The reduction potentials are also quite similar
(Table 1). This seems to indicate that the three meth-
anofullerene units in 13 behave as independent redox centers.
It should be noted that the wave amplitudes are only 2.4 times
Table 1 Electrochemical data on the reduction of C and fullerodendrons 12, 13 and 15 determined by CV and SSV on a glassy carbon
60
working electrode in CH Cl ] 0.1 M Bu NPF at room temperature
2
2
4
6
CVa
SSVb
E
E
E
E
E
E
E
1
2
3
1
2
3
4
C
c
[0.98(59)
[1.03(85)
[1.05(90)
[1.06(80)
[1.37(61)
[1.41(80)
[1.41(80)
[1.41(80)
[1.83(60)
[1.84(110)
[1.85(120)
[1.85(100)
60
12
13
15
[1.04(60)
[1.06(70)
[1.07(65)
[1.42(70)
[1.42(60)
%e
[1.90(70)
[1.90(80)
%e
[2.08d
[2.08d
%e
a Values for (E ] E )/2 in V vs. Fc/Fc` and *E in mV (in parentheses) at a scan rate of 0.1 V s~1. b Values in V vs. Fc/Fc` and slope in mV
pa
pc
pc
per log unit (in parentheses). c From ref. 22(a). d Small amplitude wave corresponding to an electrogenerated species obtained after the third
reduction step. e Badly resolved, spread out wave.
690
New J. Chem., 2000, 24, 687È695

View Online
Scheme 4 Preparation of fullerodendron 16.
larger for 13 than for 12 at the same analytical concentration
despite 13 containing three reducible methanofullerene units.
This is mainly due to the large di†erence in di†usion coeffi-
cients. The limiting current at a rotating disk electrodes is
given by the Levich equation:24 I \ 0.62 É nFACD2@3 l~1@6
d
u1@2 where n is the number of electrons exchanged, F the
Faraday constant, A the electrode area in cm2, C the analyti-
cal concentration in mol L~1, D the di†usion coefficient in
cm2 s~1, l the cinematic viscosity in cm2 s~1, and u the rota-
tion speed in rad s~1. The limiting current ratio I /I (where
d2 d1
I
stands for 13 and I for 12) reduces to: I /I \
d2
2
d1
d2 d1
(n /n ) É (D /D )2@3.
1
2
1
In this equation, the di†usion coefficient is given by the
StokesÈEinstein equation and can be reduced to D \ csts.(d/
M)1@3 where d is the density of the electroactive species and M
its molecular weight.25 Under these conditions, assuming
similar
d values, the expected current ratio becomes:
I
/I \ (n /n ) É (M /M )1@3 and is equal to 2.25. Within
d2 d1
2
1
1
2
Fig. 1 Cyclic voltammetry of fullerodendrons (a) 12, (b) 13 and (c) 15
on a glassy carbon electrode at v \ 0.1 V s~1 in CH Cl ] 0.1 M
Fig. 2 SSV of (a) 12 and (b) 13 recorded at the same concentration
(0.39 mmol L~1) in CH Cl ] 0.1 M Bu NPF on a glassy carbon
2
2
2
2
4
6
Bu NPF in the presence of ferrocene used as internal reference.
rotating electrode (u \ 209 rad s~1).
4
6
New J. Chem., 2000, 24, 687È695
691

View Online
experimental errors (due to uncertainty in the concentration),
this theoretical value is in good agreement with the observed
current ratio of 2.4 ^ 0.2, which means that each step in 13
involves three electrons.
In addition, wave analysis by plotting E vs. log I/(I [ I)
d
where I is the current, I the limiting current and E the
d
applied potential, gave straight lines for both 12 and 13.
Taking into account the fact that the slopes of the waves are
similar, the present results prove that the three meth-
anofullerene units in 13 behave e†ectively as independent
redox centers.26
By CV, fullerodendron 15 behaves like the above depicted
species [Fig. 1(c)]. By SSV, only one clearly deÐned reduction
step could be observed, the further reductions being less well
deÐned and the wave spreading out along the potential axis.
However, the slope of the Ðrst reduction wave as well as the
observed amplitude are characteristic of a simultaneous
reduction of the seven independent methanofullerene redox
centers in 15. Since a hepta-anionic species is generated after
the Ðrst reduction step, the poor resolution of the further
waves could be due to the poor solubility of this highly
charged species in CH Cl .
Fig. 3 ES mass spectrum of 12 recorded in the negative mode; the
inset shows the isotopic pattern of the anion at m/z \ 1283.2.
certainly due to the presence of residual quantities of water in
the solvent. Indeed, when a more concentrated solution of 13
is analyzed by ESMS under the same conditions, a more
intense peak at m/z \ 1226.3 is observed, showing the corre-
lation between the quantity of residual water in the solvent
and the presence of protonated species.
The ES mass spectrum obtained with 15 also showed three
peaks (Fig. 4): the expected radical hepta-anion at m/
z \ 1209.6 (calculated m/z \ 1209.55), the mono-protonated
compound at m/z \ 1411.1 and the di-protonated compound
at m/z \ 1693.1.
2
2
Mass spectrometry
Whereas the FAB-MS spectrum of methanofullerene 12
showed the expected molecular ion peak, no characteristic
peaks could be observed for the fullerodendrons of higher gen-
erations 13 and 15. In fact, due to condensation reactions
resulting probably from fullerene-fullerene interactions under
the high energy of the FAB gun or due to fullerene aggre-
gation in the matrix, the FAB-MS analysis yields only frag-
mentations. Furthermore, the molecular mass of compound
15 (8466.85 Da) is quite high for FAB analysis. Finally, no
protonation or deprotonation sites are available in 12, 13 and
15, which usually prevents FAB analysis. We have already
Other experiments using pre-ionized compounds have also
been carried out by ESMS. Indeed, the reduced species are
relatively stable and can be generated by a classical electro-
chemical reaction. The studied anions were generated by
intensiostatic reduction using tetra(n-butyl)ammonium hexa-
Ñuorophosphate (TBA-PF ) at 10~2 M as supporting electro-
6
lyte and analyzed by ESMS. Unfortunately, it was not
possible to obtain a very informative spectrum; the presence
of salts disturbs spray formation and a dramatic loss of inten-
sity is observed.
described the characterization of C by ESMS, using a new
60
Conclusion
approach based on its redox properties.10 Radical anions
(negative mode) can be generated during the ES process,
owing to the ability of the ES source to behave like an electro-
lysis cell.11 In the present case, from the electrochemical data
compounds 12, 13 and 15 appear to be good candidates for
this ESMS characterization method. The compound under
study (12, 13 or 15) was dissolved in anhydrous CH Cl and
The synthesis of fullerene-functionalized dendritic branches
containing C
spheres at each branching unit has been
60
carried out by a convergent approach using successive ester-
2
2
stirred at room temperature for 5 min. Direct analysis of this
solution yielded no observable ions. Therefore, the solution
was then carefully degassed under nitrogen in order to remove
oxygen from the sample. Indeed, in the case of reduction reac-
tions, oxygen may be reduced before the analyte, thus prevent-
ing the reduction, and therefore the detection with ESMS, of
the studied fullerene derivative. The degassed solution was
directly analyzed by ESMS in the negative mode (reduction
mode) and spectra with intense ion peaks were observed.
The ES mass spectrum obtained with 12 is depicted in Fig.
3 and shows one singly charged peak at m/z \ 1283.2
(calculated m/z \ 1283.41), corresponding to the expected
radical anion or in other words to the mono-reduced com-
pound. The isotopic pattern of this ion corresponds to the
theoretical one and conÐrms the charge state of the peak.
The ES mass spectrum obtained in the negative mode with
fullerodendron 13 shows three peaks (Fig. 4): the expected
peak at m/z \ 1226.3, corresponding to the radical tri-anion
(calculated m/z \ 1225.95), and two other peaks at m/
z \ 1839.7 and 3680.2. Since the three fullerenes behave as
independent redox centers, only the radical tri-anion was
expected. However, partial protonation of the generated tri-
anion occured, giving rise to the two other peaks correspond-
ing to the mono-protonated (m/z \ 1839.7) and to the
di-protonated (m/z \ 3680.2) species of the radical tri-anion.
These protonations are conÐrmed by the m/z values and are
Fig. 4 ES mass spectra of 13 (top) and 15 (bottom).
692
New J. Chem., 2000, 24, 687È695

View Online
mmol) and PMBCl (14.57 g, 156.61 mmol) in CH Cl (250
iÐcation and deprotection steps. The tert-butyl-protected ful-
lerodendrons containing one, three or seven methanofullerene
subunits have been characterized by ESMS, exploiting their
reduction in the electrospray source. The MS analysis of the
reduced species also conÐrmed that all the methanofullerene
subunits in the fullerodendrons of highest generation behave
as independent redox centers, as suggested by their electro-
chemical behavior. This new ionization strategy of uncharged
fullerene derivatives appears to be very efficient and o†ers new
perspectives in the characterization of complex molecular
architectures larger than 10 kDa.
2
2
mL) at room temperature. After 4 h, the reaction mixture was
Ðltered and evaporated to dryness. Column chromatography
(SiO , CH Cl È2% MeOH) yielded 2 (11.82 g, 58%). Color-
2
2 2
less oil; 1H-NMR (CDCl , 200 MHz): d \ 1.36È1.60 (m, 8H),
3
3.43 (t, J \ 6 Hz, 2H), 3.61 (t, J \ 6 Hz, 2H), 3.80 (s, 3H), 4.42
(s, 2H), 6.88 (d, J \ 8 Hz, 2H), 7.27 (d, J \ 8 Hz, 2H);
13C-NMR (CDCl , 50 MHz): d \ 25.32, 25.68, 29.34, 32.27,
3
54.94, 62.09, 69.75, 72.18, 113.42, 129.02, 130.23, 158.77.
C
9.11.
H
O (238.3): calcd C 70.56, H 9.30; found C 70.15, H
14 22
3
Compound 3. PPh (1.91 g, 5.77 mmol) was added to a
3
Experimental
stirred solution of 2 (1.1 g, 4.61 mmol) and CBr (1.91 g, 5.77
4
mmol) in dry THF (20 mL) at room temperature. After 30
min, the reaction mixture was poured into water. The aqueous
Materials and methods
layer was extracted with CH Cl (3 ] ). The combined
2
2
Reagents and solvents were purchased as reagent grade and
used without further puriÐcation. tert-Butyl 2-hydroxyacetate
was prepared according to the literature.16 All reactions were
performed in standard glassware under an inert Ar atmo-
sphere. Evaporation and concentration was carried out at
water aspirator pressure and drying in vacuo at 10~2 torr.
Column chromatography: silica gel 60 (230È400 mesh, 0.040È
0.063 mm) was purchased from E. Merck. Thin layer chroma-
tography (TLC) was performed on glass sheets coated with
organic layers were dried (MgSO ), Ðltered and evaporated to
4
yield 3 (1.1 g, 79%), which was used without further puriÐ-
cation. Colorless oil; 1H-NMR (CDCl , 200 MHz): d \ 1.38
3
(m, 4H), 1.62 (m, 2H), 1.86 (m, 2H), 3.41 (t, J \ 7 Hz, 2H), 3.45
(t, J \ 6.5 Hz, 2H), 3.81 (s, 3H), 4.43 (s, 2H), 6.89 (d, J \ 8 Hz,
2H), 7.24 (d, J \ 8 Hz, 2H); 13C-NMR (CDCl , 50 MHz):
3
d \ 25.32, 27.88, 29.47, 32.65, 33.81, 55.16, 69.78, 72.44, 113.64,
129.12, 130.58, 159.01. C
7.03; found C 55.86, H 7.02.
H
O Br (301.23): calcd C 55.82, H
14 21
2
silica gel 60 F
purchased from E. Merck, visualization by
254
UV light. UV/Vis spectra were measured on a Hitachi U-3000
spectrophotometer. IR spectra were measured on an ATI
Mattson Genesis Series FTIR instrument. NMR spectra were
recorded on a Bruker AC 200 (200 MHz) or a Bruker AM 400
(400 MHz) with solvent peaks as reference. Elemental analyses
were performed by the analytical service at the Institut
Charles Sadron, Strasbourg.
Compound 4. A mixture of 3 (6.3 g, 20.91 mmol), 3,5-dihy-
droxybenzyl alcohol (1.37 g, 9.96 mmol), and K CO (5.78 g,
2
3
41.82 mmol) in DMF (150 mL) was stirred for 20 h at 80 ¡C.
After cooling, the resulting mixture was Ðltered and evapo-
rated to dryness. The brown residue was taken up in Et O.
2
The organic layer was washed with a saturated aqueous NaCl
solution (2 ] ), dried (MgSO ), Ðltered and evaporated.
4
Column chromatography (SiO , CH Cl ÈAcOEt 8 : 2)
2
2 2
yielded 4 (3.00 g, 52%). Colorless oil; 1H-NMR (CDCl , 200
Electrochemistry. The electrochemical studies were carried
3
MHz): d \ 1.45È1.78 (m, 16H), 3.47 (t, J \ 6 Hz, 4H), 3.80 (s,
out in CH Cl (Fluka, spectroscopic grade used without
2
2
6H), 3.95 (t, J \ 6 Hz, 4H), 4.42 (s, 4H), 4.60 (s, 2H), 6.37 (t,
J \ 2 Hz, 1H), 6.50 (d, J \ 2 Hz, 2H), 6.90 (d, J \ 8 Hz, 4H),
further puriÐcation) containing 0.1 M Bu NPF (Merck, elec-
4
6
trochemical grade) as supporting electrolyte. A classical three-
electrode cell was connected to an Autolab (Eco Chemie B.V.
Utrecht, Holland) computerized electrochemical device. The
working electrode was a glassy carbon disk (3 mm in
diameter), the auxiliary electrode a platinum wire and the ref-
erence electrode an aqueous Ag/AgCl reference electrode. All
potentials are given vs. Fc/Fc` used as internal standard.
7.27 (d, J \ 8 Hz, 4H); 13C-NMR (CDCl , 50 MHz):
3
d \ 25.72, 25.80, 29.03, 29.49, 55.04, 64.93, 67.66, 69.81, 72.32,
100.20, 104.76, 113.54, 129.06, 130.29, 143.29, 158.90, 160.21;
IR (CH Cl ): l \ 3599 cm~1 (OH). C
H
O É 0.5 H O
2
2
35 48
7
2
(589.77). calcd C 71.28, H 8.37; found C 71.55, H 8.33.
Compound 5. A mixture of 4 (3.00 g, 5.16 mmol) and
MeldrumÏs acid (0.75 g, 5.16 mmol) was heated at 110È120 ¡C
for 3 h. After cooling, drying (10~2 torr, 24 h) provided 5 (3.40
g, 99%), which was used without further puriÐcation. Pale
Electrospray mass spectrometry. Samples for ESMS were
prepared by dissolving the compound under study in anhy-
drous CH Cl at a concentration of 10~4 M. After stirring at
2
2
yellow oil; 1H-NMR (CDCl , 200 MHz): d \ 1.44È1.80 (m,
room temperature for 5 min, the solution was intensively
degassed under nitrogen to remove oxygen from the sample.
The degassed solution was then directly analyzed by ESMS.
Negative ES mass spectra were obtained on a Quattro II
(Micromass, Altrincham, UK) ES triple quadrupole mass
spectrometer. The ES source was heated to 45 ¡C. The sam-
3
16H), 3.47 (t, J \ 6 Hz, 4H), 3.48 (s, 2H), 3.80 (s, 6H), 3.93 (t,
J \ 6 Hz, 4H), 4.46 (s, 4H), 5.14 (s, 2H), 6.40 (t, J \ 2 Hz, 1H),
6.48 (d, J \ 2 Hz, 2H), 6.87 (d, J \ 8 Hz, 4H), 7.26 (d, J \ 8
Hz, 4H); 13C-NMR (CDCl , 50 MHz): d \ 25.71, 25.76,
3
28.96, 29.38, 40.83, 55.10, 67.12, 67.80, 69.77, 72.28, 101.18,
106.14, 113.83, 129.24, 130.23, 137.10, 159.00, 160.27, 166.53,
169.40.
pling cone voltage (V ) was at 100 V; at this voltage no frag-
c
mentation processes were detected and reproducible spectra
were obtained. Sample solutions were introduced into the
mass spectrometer source with a syringe pump (Harvard type
55 1111: Harvard Apparatus Inc., South Nattick, MA, USA)
with a Ñow rate of 4 ll min~1. Calibration was performed
using protonated horse myoglobin. Scanning was performed
in the MCA (multi channel analyzer) mode and several scans
were summed to obtain the Ðnal spectrum.
Compound 6. DCC (1.05 g, 5.10 mmol) and DMAP (0.10 g,
0.85 mmol) were added to 5 (3.40 g, 5.10 mmol) and tert-butyl
2-hydroxyacetate (0.56 g, 4.25 mmol) in CH Cl (50 mL) at
2
2
0 ¡C. The mixture was allowed to slowly warm to room tem-
perature (1 h) and, after stirring for 24 h, Ðltered and evapo-
rated. Column chromatography (SiO , CH Cl ) yielded 6
2
2
2
(3.03 g, 91%). Colorless oil; 1H-NMR (CDCl , 200 MHz):
3
d \ 1.33 (s, 9H), 1.33È1.78 (m, 14H), 3.43 (t, J \ 6 Hz, 4H),
Syntheses
3.51 (s, 2H), 3.80 (s, 6H), 3.93 (t, J \ 6 Hz, 4H), 4.41 (s, 4H),
4.55 (s, 2H), 5.10 (s, 2H), 6.36 (t, J \ 2 Hz, 1H), 6.46 (d, J \ 2
Hz, 2H), 6.90 (d, J \ 8 Hz, 4H), 7.27 (d, J \ 8 Hz, 4H);
Compound 2. Freshly prepared Ag O (29.4 g, 126.92 mmol)
2
was added to a stirred solution of 1,6-hexanediol (10 g, 84.61
13C-NMR (CDCl , 50 MHz): d \ 25.77, 25.86, 27.84, 29.05,
3
New J. Chem., 2000, 24, 687È695
693

View Online
106.42, 136.87, 160.42, 166.49, 171.22; IR (CH Cl ): l \ 1747
29.56, 40.86, 55.10, 61.73, 67.16, 67.77, 69.85, 72.38, 82.54,
100.99, 106.29, 113.58, 129.08, 130.55, 137.06, 158.95, 160.26,
165.66, 166.04; IR (CH Cl ): l \ 1748 cm~1 (C2O).
2
2
cm~1 (C2O).
2
2
Compound 11. DCC (4.58 g, 22.19 mmol) and DMAP (450
mg, 3.69 mmol) were added to tert-butyl 2-hydroxyacetate
(2.44 g, 18.49 mmol) and 10 (10 g, 22.19 mmol) in CH Cl (150
Compound 7. DBU (0.084 mL, 0.582 mmol) was added at
room temperature to a solution of 6 (0.2 g, 0.254 mmol), C
60
(0.168 g, 0.232 mmol), and I (0.074 g, 0.291 mmol) in toluene
2
2 2
mL) at 0 ¡C. The mixture was allowed to slowly warm to
room temperature (1 h) and, after stirring for 24 h, Ðltered and
evaporated. Column chromatography (SiO , CH Cl ) yielded
(200 mL), and the mixture was stirred for 6 h. Filtration
through a short plug of silica (CH Cl ) followed by column
2
2
2
2 2
chromatography (SiO , CH Cl È1% AcOEt) yielded 7 (106
11 (9.77 g, 93%). Colorless oil; 1H-NMR (CDCl , 200 MHz):
2
2
2
3
mg, 30%). Dark red glassy product; 1H-NMR (CDCl , 200
d \ 0.89 (t, J \ 6 Hz, 6H), 1.35 (m, 20H), 1.49 (s, 9H), 1.77 (m,
3
MHz): d \ 1.23È1.78 (m, 16H), 1.53 (s, 9H), 3.43 (t, J \ 6 Hz,
4H), 3.53 (s, 2H), 3.91 (t, J \ 6 Hz, 4H), 4.55 (s, 2H), 5.10 (s,
2H), 6.41 (t, J \ 2 Hz, 1H), 6.46 (d, J \ 2 Hz, 2H); 13C-NMR
4H), 3.80 (s, 6H), 3.88 (t, J \ 6 Hz, 4H), 4.42 (s, 4H), 4.82 (s,
2H), 5.47 (s, 2H), 6.38 (t, J \ 2 Hz, 1H), 6.60 (d, J \ 2 Hz, 2H),
6.87 (d, J \ 8 Hz, 4H), 7.27 (d, J \ 8 Hz, 4H); 13C-NMR
(CDCl , 50 MHz): d \ 13.99, 22.54, 25.93, 27.83, 29.12, 29.23,
3
31.70, 40.87, 61.71, 67.14, 67.90, 82.49, 101.00, 106.26, 137.09,
(CDCl , 50 MHz): d \ 26.02, 28.09, 29.23, 29.72, 51.80, 55.26,
160.31, 165.66, 166.02; IR (CH Cl ): l \ 1748 cm~1 (C2O).
3
2 2
63.11, 67.96, 69.13, 70.00, 71.25, 72.53, 83.09, 101.65, 107.37,
C
9.40.
H
O (564.8): calcd C 68.06, H 9.28; found C 68.27, H
32 52
8
113.73, 129.21, 130.68, 136.61, 138.21, 139.88, 140.85, 141.85,
142.16, 142.97, 143.80, 144.45, 144.62, 144.91, 145.19, 159.05,
160.37, 163.07, 165.35; IR (CH Cl ): l \ 1747 cm~1 (C2O);
Compound 12. DBU (0.310 mL, 2.08 mmol) was added at
room temperature to a solution of 11 (516 mg, 0.915 mmol),
2
2
UV/Vis (CH Cl ): j
(e) \ 258 (108 000), 326 (33 200), 425
2
2
max
(2150), 482 (1210), 686 nm (140). C
(1542.1): calcd C 81.39, H 3.86; found C 81.30, H 3.95.
H
O
É 0.5CH Cl
C
(600 mg, 0.832 mmol), and I (264 mg, 1.04 mmol) in
104 58 12
2
2
60
2
toluene (600 mL), and the mixture was stirred for 6 h. Fil-
tration through a short plug of silica (toluene) followed by
Compound 1. DDQ (220 mg, 0.968 mmol) was added to a
solution of 7 (660 mg, 0.44 mmol) in 18 : 1 CH Cl ÈH O (50
column chromatography (SiO , toluene) yielded 12 (470 mg,
2
44%). Dark red glassy product; 1H-NMR (CDCl , 200
3
2
2
2
mL) and the mixture was stirred for 1 h. The resulting CH Cl
MHz): d \ 0.89 (t, J \ 6 Hz, 6H), 1.28 (m, 20H), 1.54 (s, 9H),
2
2
solution was washed with an aqueous NaHCO solution, then
1.74 (m, 4H), 3.90 (t, J \ 6 Hz, 4H), 4.84 (s, 2H), 5.48 (s, 2H),
6.40 (t, J \ 2 Hz, 1H), 6.62 (d, J \ 2 Hz, 2H); 13C-NMR
3
with a saturated aqueous NaCl solution, dried (MgSO ), Ðl-
4
tered and evaporated. Column chromatography (SiO ,
2
(CDCl , 50 MHz): d \ 14.12, 22.67, 26.09, 28.07, 29.25, 29.38,
3
CH Cl È2% MeOH) yielded 1 (462 mg, 84%). Dark red glassy
29.66, 31.80, 51.80, 63.08, 68.09, 69.12, 71.25, 83.06, 101.64,
2
2
product; 1H-NMR (CDCl , 200 MHz): d \ 1.40È1.77 (m,
107.34, 136.58, 138.22, 139.84, 140.84, 141.79, 141.88, 142.15,
142.85, 142.94, 143.77, 143.83, 144.42, 144.46, 144.61, 144.85,
144.92, 145.20, 160.40, 162.92, 163.05, 165.32; IR (CH Cl ):
3
16H), 1.58 (s, 9H), 3.68 (t, J \ 6 Hz, 4H), 3.90 (t, J \ 6 Hz,
4H), 4.85 (s, 2H), 5.50 (s, 2H), 6.40 (t, J \ 2 Hz, 1H), 6.62 (d,
2
2
J \ 2 Hz, 2H); 13C-NMR (CDCl , 50 MHz): d \ 25.48,
l \ 1748 cm~1 (C2O); UV/Vis (CH Cl ):
j
(e) \ 258
3
2
2
max
25.86, 28.00, 29.12, 32.57, 51.30, 62.72, 63.03, 67.84, 69.01,
(107 000), 326 (35 300), 425 (2320), 482 (1310), 688 nm (170);
71.15, 83.05, 101.57, 107.25, 136.56, 138.15, 139.77, 140.72,
140.80, 141.69, 141.79, 142.07, 142.75, 142.90, 143.67, 143.74,
144.35, 144.53, 144.76, 144.85, 145.09, 160.24, 162.82, 162.96,
165.31; IR (CH Cl ): l \ 3600 (OH), 1748 cm~1 (C2O);
ESMS: see Fig. 3. C
found C 86.56, H 3.83.
H
O (1283.4): calcd C 86.10, H 3.93;
92 50
8
Compound 8. A mixture of 12 (2.00 g, 1.56 mmol) and
2
2
UV/Vis (CH Cl ): j
(e) \ 257 (136 000), 326 (40 600), 425
CF CO H (25 mL) in CH Cl (100 mL) was stirred at room
2
2
max
3
2
2 2
(2850), 482 (1540), 686 nm (200). C
H
O
(1259.3): calcd C
temperature for 1 h. The reaction mixture was then washed
88 42 10
83.93, H 3.36; found C 83.55, H 3.46.
with water (until pH was near neutrality), dried (MgSO ), Ðl-
4
tered and evaporated to yield 8 (1.86 g, 97%). Dark red glassy
Compound 9. A mixture of K CO (41.5 g, 300 mmol), 3,5-
product; 1H-NMR (CDCl , 200 MHz): d \ 0.88 (t, J \ 6 Hz,
2
3
3
dihydroxybenzyl alcohol (10 g, 71.36 mmol) and 1-
bromooctane (35.6 g, 142.78 mmol) in DMF (150 mL) was
heated at 70 ¡C for 41 h, then cooled to room temperature.
After Ðltration through celite (CH Cl ) and evaporation, the
6H), 1.28 (m, 20H), 1.75 (m, 4H), 3.90 (t, J \ 6 Hz, 4H), 5.01 (s,
2H), 5.45 (s, 2H), 6.41 (t, J \ 2 Hz, 1H), 6.60 (d, J \ 2 Hz, 2H);
IR (CH Cl ): l \ 1748 cm~1 (C2O); UV/Vis (CH Cl ): j
2
2
2
2
max
(e) \ 258 (115 200), 325 (35 600), 425 (3260), 488 (1855), 687 nm
2
2
residue was taken up in Et O. The organic layer was washed
(180). C
86.09, H 3.71.
H
O (1227.3): calcd C 86.12, H 3.45; found C
2
88 42
8
with
a
saturated aqueous NaCl solution (2 ] ), dried
(MgSO ), Ðltered and evaporated. Column chromatography
4
(SiO , CH Cl Èhexane 1 : 1) yielded 9 (23.48 g, 90%). Color-
Compound 13. DCC (143 mg, 0.694 mmol) and DMAP
(13.58 mg, 0.111 mmol) were added to 8 (852 mg, 0.694 mmol),
1 (350 mg, 0.277 mmol), and HOBt (catalytic amount) in
CH Cl (150 mL) at 0 ¡C. The mixture was allowed to slowly
2
2 2
less oil; 1H-NMR (CDCl , 200 MHz): d \ 0.89 (t, J \ 6.5 Hz,
3
6H), 1.30 (m, 20H), 1.73 (m, 4H), 3.93 (t, J \ 6.5 Hz, 4H), 4.60
(br s, 2H), 6.38 (t, J \ 2 Hz, 1H), 6.49 (d, J \ 2 Hz, 2H);
2
2
13C-NMR (CDCl , 50 MHz): d \ 14.05, 22.61, 26.00, 29.22,
warm to room temperature (1 h) and, after stirring for 24 h,
3
29.31, 31.77, 65.28, 67.99, 110.45, 104.96, 143.19, 160.43; IR
Ðltered and evaporated. Column chromatography (SiO ,
2
(CH Cl ): l \ 3604 cm~1 (OH). C
H
O
(364.6): calcd C
CH Cl ) yielded 13 (720 mg, 70%). Dark red glassy product;
2
2
23 40
3
2 2
75.78, H 11.06; found C 75.72, H 11.20.
1H-NMR (CDCl , 200 MHz): d \ 0.88 (t, J \ 6 Hz, 12H),
3
1.20È1.43 (m, 52H), 1.53 (s, 9H), 1.77 (m, 12H), 3.86 (t, J \ 6
Compound 10. A mixture of 9 (11 g, 30.16 mmol) and
MeldrumÏs acid (4.35 g, 30.16 mmol) was heated at 110È120 ¡C
for 3 h. After cooling, drying (10~2 torr, 24 h) provided 10
(13.55 g, 99%), which was used without further puriÐcation.
Hz, 4H), 3.90 (t, J \ 6, 8H), 4.22 (t, J \ 6 Hz, 4H), 4.84 (s, 2H),
4.94 (s, 4H), 5.46 (s, 6H), 6.33 (t, J \ 2 Hz, 1H), 6.40 (t, J \ 2
Hz, 2H), 6.57 (d, J \ 2 Hz, 2H), 6.60 (d, J \ 2 Hz, 4H);
13C-NMR (CDCl , 50 MHz): d \ 14.14, 22.65, 25.56, 25.82,
3
Pale yellow oil; 1H-NMR (CDCl , 200 MHz): d \ 0.89 (t,
26.09, 28.05, 28.46, 29.10, 29.25, 29.37, 31.77, 51.22, 51.23,
3
J \ 6 Hz, 6H), 1.30 (m, 20H), 1.76 (m, 4H), 3.50 (s, 2H), 3.91 (t,
62.57, 63.05, 65.71, 67.73, 68.05, 69.02, 71.12, 71.18, 83.02,
101.54, 107.15, 107.28, 136.52, 136.65, 138.12, 138.39, 139.73,
139.84, 140.83, 141.72, 141.82, 142.10, 142.75, 142.81, 142.91,
143.68, 143.76, 144.32, 144.40, 144.55, 144.79, 144.88, 145.10,
J \ 6 Hz, 4H), 5.14 (s, 2H), 6.42 (t, J \ 2 Hz, 1H), 6.48 (d,
J \ 2 Hz, 2H); 13C-NMR (CDCl , 50 MHz): d \ 14.05,
3
22.61, 25.99, 29.18, 29.31, 31.77, 40.73, 67.52, 68.05, 101.25,
694
New J. Chem., 2000, 24, 687È695

View Online
thank the TMR-Project EU Nr. ERBFMRXCT980226 on
Nanometer Size Metallic Complexes for Ðnancial support of
the ESMS work. H.N. thanks the Laboratoire P. Fabre for
Ðnancial support. We are grateful to J.-D. Sauer for NMR
measurements and to L. Oswald for technical help.
145.23, 160.24, 160.38, 162.89, 165.28, 166.40; UV/Vis
(CH Cl ): j (e) \ 258 (340 000), 327 (107 700), 425 (9500),
2
2
max
482 (4500), nm 689 (570); ESMS: see Fig. 4. C
H
O
264 122 24
(3677.9): calcd C 86.22, H 3.34; found C 86.07, H 3.36.
Compound 14. A mixture of 13 (680 mg, 0.184 mmol) and
CF CO H (25 mL) in CH Cl (100 mL) was stirred at room
3
2
2 2
temperature for 1 h. The reaction mixture was then washed
References
with water (until pH was near neutrality), dried (MgSO ), Ðl-
4
1
A. Hirsch, T he Chemistry of the Fullerenes, Thieme, Stuttgart,
1994; F. Diederich, L. Isaacs and D. Philp, Chem. Soc. Rev., 1994,
23, 243; F. Diederich and C. Thilgen, Science, 1996, 271, 317; H.
Imahori and Y. Sakata, Adv. Mater., 1997, 9, 537; Y. Rubin,
Chem. Eur. J., 1997, 3, 1009; F. Diederich, Pure Appl. Chem.,
1997, 69, 395; M. Prato and M. Maggini, Acc. Chem. Res., 1998,
31, 519; T. Chuard and R. Deschenaux, Chimia, 1998, 52, 547; N.
Martin, L. Sanchez, B. Illescas and I. Perez, Chem. Rev., 1998, 98,
2527; A. L. Balch and M. M. Olmstead, Chem. Rev., 1998, 98,
2123; H. Imahori and Y. Sakata, Eur. J. Org. Chem., 1999, 2445;
F. Diederich and R. Kessinger, Acc. Chem. Res., 1999, 32, 537; F.
Diederich and M. GomezÈLopez, Chem. Soc. Rev., 1999, 28, 263;
J. L. Segura and N. Mart•n, Chem. Soc. Rev., 2000, 29, 13.
S. K. Srivastava, G. Jong, S. Leifer and W. Saunders, Rapid
Commun. Mass Spectrom., 1993, 7, 610.
D. C. Brune, Rapid Commun. Mass Spectrom., 1999, 13, 384.
C. G. Juo, L. L. Shiu, C. K.-F. Shen, T. Y. Luh and G. R. Her,
Rapid Commun. Mass Spectrom., 1995, 9, 604.
J. B. Fenn, M. Mann, C. K. Meng, S. F. Wong and C. M. White-
house, Science, 1989, 246, 64.
H. Rogniaux, A. Van Dorsselaer, P. Barth, J.-F. Biellmann, J.
Barbanton, M. van Zandt, B. Chevrier, E. Howard, A. Mitschler,
N. Potier, L. Urzhumtseva, D. Moras and A. Podjarny, J. Am.
Soc. Mass Spectrom., 1999, 10, 635.
(a) E. Leize, A. Van Dorsselaer, R. Kramer and J.-M. Lehn, J.
Chem. Soc., Chem. Commun., 1993, 990; (b) K. C. Russel, E. Leize,
A. Van Dorsselaer and J.-M. Lehn, Angew. Chem., Int. Ed. Engl.,
1994, 34, 209; (c) G. Hopgartner, C. Piguet, J. D. Henion and A.
F. Williams, Helv. Chim. Acta, 1993, 76, 1759.
S. R. Wilson and Y. Wu, J. Am. Soc. Mass Spectrom., 1993, 4,
596.
(a) S. Fujimaki, I. Kudaka, T. Sato, K. Hiraoka, H. Shinohara, Y.
Saito and K. Nojima, Rapid Commun. Mass Spectrom., 1993, 7,
1077; (b) G. Khairallah and J. B. Peel, Int. J. Mass Spectrom.,
2000, 194, 115.
tered and evaporated to yield 14 (660 mg, 98%). Dark red
glassy product; 1H-NMR (CDCl , 200 MHz): d \ 0.88 (t,
3
J \ 6 Hz, 12H), 1.27È1.43 (m, 52H), 1.70 (m, 12H), 3.87 (t,
J \ 6 Hz, 4H), 3.89 (t, J \ 6 Hz, 8H), 4.24 (t, J \ 6 Hz, 4H),
4.95 (s, 4H), 4.98 (s, 2H), 5.43 (s, 2H), 5.46 (s, 4H), 6.35 (t, J \ 2
Hz, 1H), 6.40 (t, J \ 2 Hz, 2H), 6.59 (d, J \ 2 Hz, 2H), 6.61 (d,
J \ 2 Hz, 4H); 13C-NMR (CDCl , 50 MHz): d \ 14.15,
3
22.67, 25.51, 25.80, 26.11, 28.44, 29.09, 29.25, 29.37, 29.58,
31.80, 51.10, 51.18, 62.09, 62.62, 65.79, 67.78, 68.08, 69.05,
71.09, 101.56, 107.17, 136.52, 136.65, 138.40, 138.50, 139.74,
140.80, 141.72, 141.81, 142.10, 142.81, 142.92, 143.76, 144.39,
144.55, 144.79, 144.89, 145.11, 160.27, 160.37, 162.77, 162.88,
162.97, 166.65; IR (CH Cl ): l \ 1748 cm~1 (C2O); UV/Vis
2
3
4
2
2
(CH Cl ): j
(e) \ 258 (276 000), 326 (90 700), 425 (8880),
2
2
max
480 (4000) 686 nm (530); ESMS (negative mode): m/
z \ 1207.4 ([M3~]), 1810.8 ([M3~ ] H`]).
5
6
Compound 15. DCC (11.4 mg, 0.055 mmol) and DMAP (1
mg) were added to 14 (200 mg, 0.055 mmol), 1 (27.8 mg,
2.20.10~2 mmol) and HOBt (catalytic amount) in CH Cl (50
2
2
mL) at 0 ¡C. The mixture was allowed to slowly warm to
room temperature (1 h) and, after stirring for 24 h, Ðltered and
evaporated. Column chromatography (SiO , CHCl ) yielded
7
2
3
15 (70 mg, 37%). Dark red glassy product; 1H-NMR (CDCl ,
3
400 MHz): d \ 0.88 (t, J \ 6 Hz, 24H), 1.20È1.46 (m, 116H),
8
9
1.54 (s, 9H), 1.56È1.79 (m, 28H), 3.85 (t, J \ 6 Hz, 4H), 3.86 (t,
J \ 6 Hz, 8H), 3.91 (t, J \ 6 Hz, 16H), 4.23 (t, J \ 6 Hz, 4H),
4.24 (t, J \ 6 Hz, 8H), 4.85 (s, 2H), 4.94 (s, 12H), 5.45 (s, 2H),
5.47 (s, 12H), 6.33 (t, J \ 2 Hz, 1H), 6.35 (t, J \ 2 Hz, 2H),
6.42 (t, J \ 2 Hz, 4H), 6.56 (d, J \ 2 Hz, 4H), 6.58 (d, J \ 2
10 A. Dupont, J.-P. Gisselbrecht, E. Leize, L. Wagner and A. Van
Dorsselaer, T etrahedron L ett., 1994, 33, 6083.
Hz, 2H), 6.61 (d, J \ 2 Hz, 8H); 13C-NMR (CDCl , 50
3
MHz): d \ 14.16, 22.68, 25.59, 25.87, 26.12, 28.10, 28.50, 29.26,
11 A. T. Blades, M. G. Ikonomou and P. Kebarle, Anal. Chem.,
1991, 63, 2109.
29.28, 29.40, 29.66, 31.80, 51.24, 51.50, 62.63, 65.74, 67.78,
68.09, 69.05, 71.15, 83.06, 101.56, 107.18, 136.56, 136.66, 138.12,
138.42, 138.43, 139.76, 139.77, 140.81, 140.82, 141.72, 141.84,
142.13, 142.83, 142.85, 142.94, 143.79, 144.71, 144.43, 144.57,
144.82, 144.91, 145.13, 160.30, 160.41, 162.89, 166.43; UV/Vis
12 J.-F. Nierengarten, D. Felder and J.-F. Nicoud, T etrahedron
L ett., 2000, 41, 41.
13 C. Hawker and J. M. J. Frechet, J. Chem. Soc., Chem. Commun.,
1990, 1010; G. R. Newkome, C. N. MooreÐeld and F. Vogtle,
Dendritic Molecules: Concepts, Synthesis, Perspectives, VCH,
Weinheim, 1996.
(CH Cl ): j
(e) \ 258 (550 000), 326 (190 000), 425 (19 600),
2
2
max
690 nm (2000); ESMS: see Fig. 4. C
H
O
É 3 CHCl
14 A. Bouzide and G. Sauve, T etrahedron L ett., 1997, 38, 5945.
608 266 56
(8824.9): calcd C 83.16, H 3.07; found C 83.09, H 3.18.
3
15 B.-C. Chen, Heterocycles, 1991, 32, 529.
16 J. Jurayj and M. Cushman, T etrahedron, 1992, 48, 8601.
17 C. Bingel, Chem. Ber., 1993, 126, 1957.
Compound 16. A mixture of 15 (25 mg, 2.96 ] 10~3 mmol)
18 (a) J.-F. Nierengarten, V. Gramlich, F. Cardulo and F. Diederich,
Angew. Chem., Int. Ed. Engl., 1996, 35, 2101; (b) X. Camps and A.
Hirsch, J. Chem. Soc., Perkin T rans. 1, 1997, 1595.
19 J.-F. Nierengarten, A. Herrmann, R. R. Tykwinski, M.
Ruttimann, F. Diederich, C. Boudon, J.-P. Gisselbrecht and M.
Gross, Helv. Chim. Acta, 1997, 80, 293.
and CF CO H (10 mL) in CH Cl (50 mL) was stirred at
3
2
2 2
room temperature for 3 h. The reaction mixture was then
washed with water (until pH was near neutrality), dried
(MgSO ), Ðltered and evaporated to yield 16 (20 mg, 80%).
4
Dark red glassy product; 1H-NMR (CDCl , 200 MHz):
3
d \ 0.88 (t, J \ 6 Hz, 24H), 1.26 (m, 116H), 1.74 (m, 28H), 3.92
(m, 28H), 4.22 (m, 12H), 4.94 (br s, 14H), 5.46 (br s, 14H), 6.33
20 P. J. Kocienski, Protecting Groups, Thieme, Stuttgart, 1994, pp.
52È54.
21 J.-F. Nierengarten and J.-F. Nicoud, T etrahedron L ett., 1997, 38,
(m, 3H), 6.40 (t, J \ 2 Hz, 4H), 6.55 (m, 6H), 6.60 (d, J \ 2 Hz,
7737.
8H); 13C-NMR (CDCl , 50 MHz): d \ 14.18, 22.70, 25.60,
22 (a) C. Boudon, J.-P. Gisselbrecht, M. Gross, L. Isaacs, H. L.
Anderson, R. Faust and F. Diederich, Helv. Chim. Acta, 1995, 78,
1334; (b) M. Keshavarz, B. Knight, R. C. Haddon and F. Wudl,
T etrahedron, 1996, 52, 5149; (c) D. Armspach, E. C. Constable, F.
Diederich, C. E. Housecroft and J.-F. Nierengarten, Chem. Eur.
J., 1998, 4, 723.
23 L. Echegoyen and L. E. Echegoyen, Acc. Chem. Res., 1998, 31,
593.
24 A. J. Bard and L. R. Faulkner, Electrochemical Methods: Funda-
mentals and Applications, Wiley, New York, 1980.
25 A. J. Fry, Synthetic Electrochemistry, Harper, New York, 1972.
26 F. Ammar and J. M. Saveant, J. Electroanal. Chem., 1973, 47,
215.
3
25.88, 26.15, 28.51, 29.30, 29.42, 29.89, 31.83, 51.80, 62.66,
65.82, 67.83, 68.12, 69.10, 71.15, 101.60, 107.22, 136.59, 136.60,
138.44, 138.46, 139.81, 140.85, 141.76, 141.88, 142.16, 142.95,
142.96, 142.97, 143.82, 144.45, 144.60, 144.85, 144.94, 145.15,
160.33, 160.43, 162.96, 162.98, 166.54, 166.56, 166.59; IR
(CH Cl ): l \ 1748 cm~1 (C2O); UV/Vis (CH Cl ): j
2
2
2
2
max
(e) \ 259 (546 000), 326 (187 700), 425 (23 830), 684 (1900) nm.
Acknowledgements
This work was supported by the CNRS. HN, EL and AVD
New J. Chem., 2000, 24, 687È695
695