Synthesis of trans-1, trans-2, trans-3, and trans-4 bisadducts of C 60 by regio-and stereoselective tether-directed remote functionalization

Article abstract of DOI:10.1002/chem.200401253

The double Bingel reaction of fullerene C₆₀, with bismalonates attached to a Troeger base derived tether afforded trans-1, trans-2, trans-3, and trans-4 bisadducts with excellent regioselectivity. In particular, enantiomerically pure bisadducts

Full text of DOI:10.1002/chem.200401253

Synthesis of trans-1, trans-2, trans-3, and trans-4 Bisadducts of C60 by Regio-
and Stereoselective Tether-Directed Remote Functionalization
Sergey Sergeyev,[a] Michael Schꢀr,[a] Paul Seiler,[a] Olena Lukoyanova,[b]
Luis Echegoyen,[b] and FranÅois Diederich*[a]
Abstract: The double Bingel reaction
of fullerene C60 with bismalonates at-
tached to a Trçger base derived tether
afforded trans-1, trans-2, trans-3, and
trans-4 bisadducts with excellent regio-
selectivity. In particular, enantiomeri-
cally pure bisadducts with inherently
chiral trans-2 or trans-3 addition pat-
terns were prepared starting from
enantiomerically pure bismalonates.
The absolute configuration of the
trans-2 and trans-3 bisadducts was es-
tablished from their CD spectra. The
excellent diastereoselectivity in the
double additions to give the trans-2 bis-
adducts is particularly remarkable
given the large distance between the
two reacting bonds in opposite hemi-
spheres of the fullerene that is spanned
by the tether. Now, all inherently chiral
double addition patterns are readily
available by tether-directed functionali-
zation using appropriate chiral, non-
racemic spacers.
Keywords: CD spectra · chiral aux-
iliaries · cyclic voltammetry · cyclo-
addition · fullerene · regioselectivity
Introduction
versatile and powerful synthetic methodology has become
the method of choice for selective multiple additions to full-
erenes.[4]
Regio- and, in the event, stereoselective multiple functional-
ization of fullerenes is a key issue to be addressed to pre-
pare pure adducts with well-defined addition patterns on a
reasonable scale and without tedious purification. However,
stepwise multiple additions suffer from very low regioselec-
tivity. Thus, the second addition of diethyl malonate to a
monoadduct of C60 gives a mixture of seven out of eight the-
oretically possible regioisomers.[1] Also, some interesting ad-
dition patterns are hardly available by simple, consecutive
additions due to the intrinsic reactivity of fullerene deriva-
tives.[2] In the search for a rational approach to the regiose-
lective formation of multiadducts of C60 and other fuller-
enes, Diederich and co-workers introduced the tether-direct-
ed remote functionalization in 1994.[3] Since that time, this
An interesting aspect of cis-3, trans-3, and trans-2 addition
patterns of C60 is their inherent chirality, that is, even addi-
tion of two identical addends without chirality elements of
their own gives a chiral molecule.[5] Several syntheses of op-
tically active cis-3 bisadducts of C60 using bismalonates at-
tached to optically pure threitol or 2,3-butanediol tethers
have been published.[6] However, the asymmetric synthesis
of C2-symmetrical trans-2 or trans-3 bisadducts, with the ad-
dends located in opposite hemispheres of C60, remained un-
known until recently.[7] The main challenge consisted in find-
ing a large but conformationally constrained chiral tether.
Very recently, we reported in a preliminary communication
the first example of a regio- and stereoselective synthesis of
trans-2 bisadducts of C60 using chiral tethers with the struc-
tural motif of the Trçger base.[8]
Trçger base (1) is a chiral amine with two bridgehead ni-
trogen atoms as stereogenic centers.[9] Rigidity, C2 symmetry,
and a folded geometry with nearly perpendicular planes of
two aromatic rings made derivatives of the Trçger base very
attractive for applications in supramolecular chemistry and
molecular recognition.[10] Here, we report the regio- and
stereoselective synthesis of biscyclopropanated derivatives
of C60 with inherently chiral trans-2 and trans-3 addition pat-
terns starting from bismalonates connected by the core of
the Trçger base. In addition, we describe the high-yielding,
[a] Dr. S. Sergeyev, M. Schꢀr, P. Seiler, Prof. Dr. F. Diederich
Laboratorium fꢁr Organische Chemie, ETH-Hçnggerberg
HCI, 8093 Zꢁrich (Switzerland)
Fax : (+41)1-632-1109
E-mail: diederich@org.chem.ethz.ch
[b] O. Lukoyanova, Prof. Dr. L. Echegoyen
Department of Chemistry, Clemson University
SC 29634 Clemson (USA)
Supporting information for this article is available on the WWW
under http://www.chemeurj.org/ or from the author.
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DOI: 10.1002/chem.200401253
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FULL PAPER
lem by performing the condensation of 4-iodoaniline (4)
and other halogeno-substituted anilines in trifluoroacetic
acid (TFA), using paraformaldehyde as a source of CH2O.[12]
Probably, the concentration of electrophilic, protonated
formaldehyde and, therefore, the rate of key steps of the
condensation to give a derivative of the Trçger base is in-
creased in TFA compared to the frequently applied protocol
that uses formalin and aqueous HCl in ethanol.[12b] It was
also demonstrated later that strict temperature control is ex-
tremely important, particularly when the reaction scale ex-
ceeds 1 mmol.[13] We have further optimized the published
procedure by changing, first of all, the order of addition of
the reagents. When a mixture of 4 and paraformaldehyde
was added to TFA at ꢁ158C (the melting point of TFA),
the corresponding diiodo derivative of the Trçger base,
(ꢀ)-5, was isolated in well reproducible 56–62% yield on a
20 to 100 mmol scale (Scheme 1). Furthermore, we conclud-
ed that long reaction times are less practical as they lead to
formation of unidentified side products, whereas the con-
densation to give derivatives of the Trçger base is completed
within 24 h. We also applied the optimized protocol to pre-
pare the previously unknown diiodide (ꢀ)-7 from 5-iodo-2-
methylaniline (6). In agreement with previous literature ac-
counts, an additional electron-donating methyl group in the
ortho position with respect to the nitrogen atom increases
the reactivity of the aniline and the yield of the Trçger base
derivative.[11a] Additionally, the ortho-methyl group is impor-
tant to block the attack of the electrophile at this position
and prevent the unwanted formation of other regioisomers.
The availability of halo derivatives of the Trçger base pro-
vides the opportunity to use the great variety of reactions
regioselective synthesis of trans-4 and trans-1 bisadducts of
60 by the same approach.
C
Results and Discussion
Synthesis of racemic bisadducts of C60: The synthesis of the
new fullerene bisadducts is outlined in Scheme 1 and
Scheme 2. We have chosen malonate (ꢀ)-2 as a first candi-
date to be tested in the tether-directed remote functionaliza-
tion. It should be mentioned that the intermediate diol
(ꢀ)-3 cannot be prepared by direct condensation of the cor-
responding aromatic amine with formaldehyde or a synthet-
ic equivalent thereof, the most practical route to analogues
of the Trçger base, due to acid-catalyzed formation of poly-
meric products.[11] It was also accepted until recently, that
electron-withdrawing substituents in any position of the ani-
line ring are not allowable for the successful condensation
to give derivatives of the Trçger base.[11] Fortunately, Wꢀrn-
mark and co-workers recently found a solution to this prob-
Scheme 1. Synthesis of bisadducts (ꢀ)-9, (ꢀ)-10, and (ꢀ)-14. a) (H2CO)n, CF3COOH, 08C, 24 h; b) nBuLi, THF, ꢁ788C, 10 min, then DMF, THF,
ꢁ788C ! RT, 30 min; c) LiAlH4, THF, RT 1 h; d) EtOOCCH2COCl, DMAP, THF, 08C, 16 h; e) C60, I2, DBU, toluene, 08C, 1 h. DMAP = 4-(dimethyl-
amino)pyridine, DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene, DMF = dimethylformamide.
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F. Diederich et al.
with organometallics or transition-metal catalysts for further
transformations. Thus, iodine–lithium exchange in (ꢀ)-5,
followed by the reaction of the dilithiated intermediate with
DMF afforded the corresponding dialdehyde (ꢀ)-8, which
was reduced (LiAlH4) to diol (ꢀ)-3 and then transformed
into bismalonate (ꢀ)-2 by the action of EtO2CCH2COCl in
the presence of DMAP. A modified Bingel reaction[14] of
(ꢀ)-2 with C60 afforded the trans-2 bisadduct (ꢀ)-9 as a
major product (27%). In addition, a minor amount (5%) of
the regioisomeric bisadduct (ꢀ)-10 with equatorial (e) addi-
tion pattern was obtained. Both regioisomers were isolated
by simple flash chromatography on SiO2. Diiodide (ꢀ)-7
was converted by the same approach via dialdehyde (ꢀ)-11
and diol (ꢀ)-12 into bismalonate (ꢀ)-13 (see Supporting In-
formation for the X-ray crystal structure of (ꢀ)-13). The
Bingel reaction of the latter with C60 afforded exclusively
the trans-4 configured bisadduct (ꢀ)-14.
and NMR spectroscopy. The absorption spectra of malonate
bisadducts of C60 in the region between 400 and 800 nm are
mainly determined by the structure of the fullerene chromo-
phore and nearly independent of the structure of addends.
Therefore, they can be used as “fingerprints” for the identi-
fication of addition patterns (see Supporting Informa-
tion).[7b,c] For all synthesized derivatives (ꢀ)-9, (ꢀ)-10,
(ꢀ)-14, and (ꢀ)-19, the absorption spectra were almost
identical to those reported for the corresponding bis(diethyl
malonate) adducts C62(COOEt)4.[16] The 1H and 13C NMR
spectra perfectly reflect the C2 symmetry of (ꢀ)-9 and
(ꢀ)-19, and the C1 symmetry of (ꢀ)-10 and (ꢀ)-14.
In theory, the described tether-directed double addition to
C60 can give various diastereoisomers with respect to the rel-
ative orientation of the ethoxycarbonyl residues at the two
methano-bridge atoms.[17] There are three (in–in, in–out, and
out–out) potential isomers for trans-2 and trans-4 adducts;
trans-1 addition can yield two (out–out and in–out) diaster-
eoisomers, and four diastereoisomers exist for the e pattern.
However, all bisadducts (ꢀ)-9, (ꢀ)-10, (ꢀ)-14, and (ꢀ)-19
were isolated as single racemates, and the out-out configura-
tion (as depicted in Scheme 1 and 2) was assigned for all
compounds.
The configuration of trans-1 bisaduct (ꢀ)-19 was also con-
firmed by X-ray crystal structure analysis (Figure 1). Sur-
prisingly, only one, namely the (R,R)-configured enantiomer
crystallized out of a solution of (ꢀ)-19 in a mixture of
CH2Cl2 and CHCl3. The absolute configuration was clearly
established by X-ray analysis, that is, by determining the ab-
solute structure parameter. Thus we observed a relatively
rare example of spontaneous resolution of a racemic mix-
ture. To the best of our knowledge, this is the first example
We were also interested in testing a larger tether derived
from a naphthalene analogue of the Trçger base. Diol (ꢀ)-
17 (Scheme 2) was prepared by direct condensation[11] of
amino alcohol 16 (synthesized by reduction of the commer-
cially available amino acid 15) with formaldehyde in HCl
and then converted to bismalonate (ꢀ)-18. Subsequent
Bingel reaction of (ꢀ)-18 with C60 afforded exclusively
trans-1 bisadduct (ꢀ)-19 in remarkable 58% yield. It should
be noted that trans-1 biscyclopropanated adducts of C60
have been prepared previously with the aid of crown ether-
derived tethers which require relatively tedious synthesis,[15]
while preparation of diol (ꢀ)-17 is very simple and high-
yielding.
The addition patterns of bisadducts (ꢀ)-9, (ꢀ)-10, (ꢀ)-
14, and (ꢀ)-19 were unequivocally established using UV/Vis
Scheme 2. Synthesis of bisadducts (ꢀ)-19, (ꢀ)-23a, and (ꢀ)-23b. a) LiAlH4, THF, reflux, 2 h; b) H2CO/H2O, HCl, EtOH, RT, 24 h; c) EtOOCCH2COCl,
DMAP, THF or DMF, 08C, 16 h; d) C60, I2, DBU, toluene, 08C, 1 h; e) 4-(Ethoxycarbonyl)phenylboronic acid, [Pd(PPh3)4], K2CO3, toluene/EtOH/H2O,
reflux, 1.5 h.
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Bisadducts of C60
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only the ordered solvent mole-
cules are considered here).
Each fullerene molecule makes
a short O···C contact of 3.09 ꢃ
to a neighboring molecule of
solvent. In addition, each full-
erene is involved in 29 inter-
molecular contacts (3.12 to
3.50 ꢃ) to neighbouring fuller-
enes. The shortest intermolecu-
lar contact between a naphthyl
unit and the C60 sphere of
3.12 ꢃ is indicated in Figure 2
as a dashed line.
To prepare bisadducts with
the trans-3 addition pattern,
we explored biphenyl deriva-
tives of the Trçger base, since
they offer the opportunity for
fine-tuning both geometry and
extension of the tether by plac-
ing reactive groups in various
positions of the terminal
phenyl rings. Suzuki cross-cou-
pling is the most powerful and
most frequently used synthetic
Figure 1. Crystal structure of trans-1 bisadduct (R,R)-19. Molecules of CH2Cl2 are omitted for clarity. Atomic
displacement parameters obtained at 238 K are drawn at the 30% probability level.
for a chiral fullerene. In this connection it should be men-
tioned that crystallization of this compound is difficult and
time-consuming. For the present analysis, only one suitable
crystal was available and thus we cannot exclude that crys-
tals of the (S,S)-enantiomer and the racemic compound can
be obtained.
The symmetry of the fullerene bisadduct (R,R)-19 is ap-
proximately C2. With respect to the free C60 skeleton (with a
mean diameter of ca. 7.07 ꢃ), the bridgehead atoms C1, C2,
C55, C60 of the cyclopropane rings protrude out by about
0.13 ꢃ, as observed, for example, in a hexakisadduct of
C60.[18] Semiempirical calculations[19] of malonate (R,R)-18
gave a distance of 12.86 ꢃ between the two methylene
groups attached to the naphthyl moieties of the modified
Trçger base tether. The calculated value deviates only slight-
ly from the observed corresponding distance of 12.80 ꢃ be-
tween C65 and C91. This result indicates very small strain in
the spacer which probably accounts for the observed high
yield of the double Bingel cycloaddition. The planar naph-
thyl subunits C66–C75 and C81–C90 are in close contact
route to biaryls.[20] Reaction of diiodide (ꢀ)-5 with 4-(ethox-
ycarbonyl)phenylboronic acid in the presence of [Pd(PPh3)4]
afforded diester (ꢀ)-20 in 81% yield. Subsequent reduction
with LiAlH4 gave diol (ꢀ)-21, which was converted to bis-
malonate (ꢀ)-22 by the same method as described above
(see Supporting Information for the X-ray crystal structure
of (ꢀ)-22). Bingel reaction of bismalonate (ꢀ)-22 with C60
afforded two diastereoisomeric bisadducts (ꢀ)-23a and
(ꢀ)-23b in a 5.4:1 ratio which demonstrate identical absorp-
tion spectra and have, therefore, the same addition pattern,
ꢁ
with the C60 skeleton. The [6,5] bond C5 C19 is nearly on
top of the six-membered ring C66–C71, making four short
intramolecular contacts between 3.22 and 3.33 ꢃ. On the
other side, there are also four short contacts between the
[6,5] bond C37–C53 and the six-membered ring C83–C90,
with distances between 3.26 and 3.37 ꢃ.
The crystal packing based on its calculated density
(1.625 gcmꢁ3), as well as on the analysis of intermolecular
contacts is quite compact, as expected. The overall arrange-
ment of a hexagonal close-packed layer, with solvent mole-
cules sitting in the cavities, is shown in Figure 2 (note that
Figure 2. Crystal packing of (R,R)-19. Only ordered molecules of CH2Cl2
are shown for clarity. The shortest intermolecular contact between the
naphthyl unit of a spacer and a C60 sphere (3.12 ꢃ) is shown as a dashed
line.
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F. Diederich et al.
1
identified as trans-3. The H NMR spectra of (ꢀ)-23a and
trum (Figure 3) with those of previously reported optically
pure trans-2 derivatives of C60.[7] Accordingly, double addi-
tion of (R,R)-2 gave exclusively (R,R,f,sC)-9.
(ꢀ)-23b clearly indicated C1-symmetry for both products. In
addition, in the 13C NMR spectra of the major product, (ꢀ)-
23a, 75 of expected 76 signals in the C(sp2)-region were ob-
served, thus undoubtedly confirming C1 symmetry.
The formation of three (in–in, in–out, and out–out) iso-
mers is theoretically possible also for the trans-3 bisadduct
of C60.[17] However, both in–in and out–out adducts should
have C2 symmetry due to the matching of the C2 symmetry
of the Trçger base unit with the same symmetry of the
trans-3 addition pattern, and have to be excluded on the
basis of the NMR data. Therefore, both isolated bisadducts,
(ꢀ)-23a and (ꢀ)-23b must have the in–out trans-3 configu-
ration. Accordingly, they are diastereoisomeric pairs of
enantiomers with (S,S,f,sA)/(R,R,f,sC) and (S,S,f,sC)/(R,R,f,sA)
configurations (Scheme 2).[21] Absolute configurations of
23a/23b were established later with the aid of enantiomeri-
cally pure 22 (see below).
Figure 3. CD spectra of (S,S,f,sA)-9 (solid line) and (R,R,f,sC)-9 (dashed
line) in CHCl3.
Enantiomerically pure bismalonates and bisadducts of C60:
Since the trans-2 and trans-3 addition patterns are inherently
chiral, it was particularly attractive to prepare the corre-
sponding bisadducts using nonracemic 2 and 22. It was
known since the work of Prelog and Wieland[9c] that the res-
olution of the Trçger base via diastereoisomeric salts with
optically active acids is generally not feasible due to rela-
tively rapid racemization in the acidic media. Consequently,
in a pioneering approach, the authors developed the first
resolution of the Trçger base by chromatography on a chiral
stationary phase (CSP) consisting of a specially prepared
lactose.[9c] We succeeded in separating the enantiomers of
bismalonate 2 on a Chiralcel OJ HPLC column with a
tris(4-methylbenzoyl)cellulose derivative as CSP. In the case
of 22, separation of enantiomers was achieved on the (S,S)-
Whelk O1 stationary phase with a covalently bound chiral
selector derived from a 3,4-disubstituted 1,2,3,4-tetrahydro-
phenanthrene.
The high asymmetric induction in the double addition of
(S,S)-2 and (R,R)-2 to C60 is remarkable given the very large
distance between the two reacting fullerene bonds that is
spanned by the tether. It was rationalized by using semiem-
pirical PM3 calculations of the optimized geometries and
heats of formation of the potential diastereoisomeric bisad-
ducts.[19] Bisadduct (S,S,f,sA)-9 was calculated to be dramati-
cally more favorable (DDH=29.4 kcalmolꢁ1) than its theo-
retically possible diastereoisomer (S,S,f,sC)-9 (Figure 4). The
The absolute configuration of (+)-2 was assigned as (S,S)
based on the close similarity of its CD spectrum with that of
(+)-(S,S)-1 (see Supporting Information). The absolute con-
figuration of the latter was undoubtedly determined previ-
ously from the X-ray structure of the salt with (ꢁ)-1,1’-bi-
naphthalene-2,2’-diyl hydrogen phosphate.[22] Similarly, we
assigned the absolute configurations of (ꢁ)-22 and (+)-22 as
(R,R) and (S,S), respectively, based on the sign of the
Cotton effect for the longest-wavelength absorption band in
their CD-spectra (see Supporting Information). However,
this assignment should be treated with some caution, since
the structure of the chromophore in 22 is somewhat differ-
ent from that in 1 or 2.
Figure 4. Energy-minimized structures of (S,S,f,sA)-9 (left) and (S,S,f,sC)-9
(right). Ethyl esters have been substituted by methyl esters for clarity.
calculated stereoselectivity is in perfect agreement with the
experimental finding, assuming that the thermodynamic sta-
bility of the bisadducts is reflected in the transition state of
the second cyclopropanation step that leads to macrocycliza-
tion and determines the absolute configuration of the addi-
tion pattern.[6a]
Double Bingel addition of enantiomerically pure (S,S)-2
and (R,R)-2 to C60 afforded two enantiomeric adducts
(S,S,f,sA)-9 (for NMR spectra, see Supporting Information)
and (R,R,f,sC)-9, respectively, with perfect diastereoselectivi-
ty.[21] Double addition of (S,S)-2 to C60 resulted in the forma-
tion of the bisadduct with a (f,sA)-configured fullerene
moiety, which was established by comparison of its CD spec-
As described above, double Bingel addition of racemic
bismalonate (ꢀ)-22 leads to two diastereoisomeric pairs of
enantiomers (ꢀ)-23a/(ꢀ)-23b. We repeated this addition
with enantiomerically pure bismalonates (S,S)-22 and (R,R)-
22, isolated all four diastereoisomers (S,S,f,sA)-23a, (S,S,f,sC)-
23a, (R,R,f,sA)-23b, and (R,R,f,sC)-23b, and assigned their
absolute configuration from their CD spectra (Figure 5). As
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Bisadducts of C60
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relative and absolute configuration. Definitely, these results
should also be treated with some caution, as the energy dif-
ference between two diastereoisomers is very small. Howev-
er, the results of the calculation are in good agreement with
the experimentally found moderate diastereoselectivity (d.r.
85:15) in favor of the (f,sA) addition pattern in the case of
the (S,S)-configured bismalonate.
The very high yield obtained in the synthesis of trans-1 bi-
sadduct (ꢀ)-19, together with the X-ray crystallographic
analysis (Figure 1), suggested the possibility of a special in-
tramolecular interaction between the naphthalene moieties
of the tether and the fullerene core, not present in other
conjugates, which could contribute to the stereoselectivity of
the Bingel macrocyclization reaction. To probe this further,
electrochemical experiments were performed with the trans-
1, trans-2, and trans-4 bisadducts (ꢀ)-19, (ꢀ)-9, and (ꢀ)-14,
using cyclic voltammetry (CV), Osteryoung square wave
voltammetry (OSWV), and controlled potential electrolysis
(CPE).
Figure 5. CD spectra of (R,R,f,sC)-23a (black), (R,R,f,sA)-23a (red),
(S,S,f,sA)-23b (gray), (S,S,f,sC)-23b (blue), and (R,R)-22 (green) in CHCl3.
expected, enantiomeric pairs of bisadducts (S,S,f,sA)-23a/
(R,R,f,sC)-23b or (S,S,f,sC)-23a/(R,R,f,sA)-23b display oppo-
site Cotton effects over the entire spectral range. On the
other hand, diastereoisomeric pairs (S,S,f,sA)-23a/(S,S,f,sC)-
23a or (R,R,f,sA)-23b/(R,R,f,sC)-23b show some deviation
from mirror image in the range 270–340 nm due to the own
Cotton effect of the Trçger base unit, which has the same
configuration in each pair of diastereoisomers while configu-
rations of fullerene chromophores are opposite. Subtraction
of the spectrum of (S,S)-22 from the spectra of (S,S,f,sA)-23a
and (S,S,f,sC)-23a gave “pure” CD spectra of the oppositely
configured fullerene chromophores (Figure 6). They are
The CVs of the three compounds are presented in
Figure 7, and the potential scale is referenced to internal fer-
Figure 7. CV of a) 0.2 mm (ꢀ)-19, b) 0.2 mm trans-2 (ꢀ)-9, and c) 0.2 mm
(ꢀ)-14 in CH2Cl2, 0.1m Bu4NPF6, scan rate 100 mVsꢁ1, room tempera-
ture.
rocene, shown at 0 V. In all three cases, the first reduction
process is chemically and electrochemically reversible (see
Table 1). However, on the CV time scale, the second reduc-
tion process for the trans-2 and trans-4 bisadducts (ꢀ)-9 and
(ꢀ)-14 is chemically irreversible, as evidenced by the ap-
pearance of decreased anodic currents on the return scan,
and the appearance of extra anodic waves. This is the ex-
pected result, since malonate adducts are known to be un-
stable at the second reduction process, a transformation we
discovered and called retro-Bingel or retro-cyclopropana-
tion reaction.[23] Interestingly, trans-1 adduct (ꢀ)-19 exhibits
perfectly reversible behavior for the first two reduction
processes, on the CV time scale. This indicates higher stabil-
ity of this malonate adduct relative to the others, at least
under electron-reducing conditions, possibly the result of
the naphthalene–fullerene interaction. However, the first re-
duction potential of trans-1 bisadduct (ꢀ)-19 is identical to
Figure 6. CD spectra of (f,sC) (solid line) and (f,sA) (dashed line) config-
ured fullerene chromophores with trans-3 addition pattern, obtained by
subtraction of the CD spectrum of (R,R)-22 from the spectra of
(R,R,f,sC)-23a and (R,R,f,sA)-23a, respectively.
merely identical to the previously published CD spectra of
enantiomerically pure trans-3 bis(diethyl malonate) adducts
C62(COOEt)4,[7] thus allowing assignment of the absolute
configuration of the fullerene chromophore. The major
product from addition of (S,S)-22 to C60 has (S,S,f,sA), and
the minor one (S,S,f,sA) configuration. According to calcula-
tions of optimized geometries and heats of formation,[19]
(S,S,f,sA)-23a is indeed by 0.9 kcalmolꢁ1 more favorable than
(S,S,f,sC)-23a, thus supporting the correct assignment of the
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F. Diederich et al.
Table 1. Electrochemical potentials (V) and DEpp (mV, in parentheses) versus Fc/Fc+, scan rate 100 mVsꢁ1
.
tion patterns of C60 are readi-
ly available by this versatile
methodology. This result
from extensive research ef-
forts is not only of fundamen-
tal but also of technological
interest since enantiomeri-
cally pure fullerene deriva-
tives are becoming promising
[a]
C60
trans-1 ((ꢀ)-
trans-2 ((ꢀ)- trans-4 ((ꢀ)-
trans-1
(24)[c]
trans-1 ((ꢀ)-
25)[c]
trans-2 ((ꢀ)-
26)[c]
19)[b]
9)[b]
14)[b]
E 11=2 ꢁ0.98 (65) ꢁ1.17 (69)
E 21=2 ꢁ1.37 (67) ꢁ1.57(66)
ꢁ1.11(65)
ꢁ1.17(70)
ꢁ0. 94(77) ꢁ1.04(70)
ꢁ1.02(79)
ꢁ1.52[d]
ꢁ1.61[d]
ꢁ1.36[d]
ꢁ1.51[d]
ꢁ1.48[d]
[a] In CH3CN/toluene, taken from reference [24]. [b] In CH2Cl2 in the presence of 0.1m Bu4NPF6. [c] In CH3CN/
CH2Cl2 in the presence of 0.1m Bu4NPF6, taken from reference [15a]. [d] Only cathodic potential is given.
that of (ꢀ)-14, while (ꢀ)-9 is easier to reduce by 60 mV.
The origin of these differences is not clear at the present
time. Due to the irreversible nature of the second reduction
process for (ꢀ)-9 and (ꢀ)-14, it is not possible to report
E 21=2 values, but based on the peak potentials observed,
trans-1 and trans-4 bisadducts (ꢀ)-19 and (ꢀ)-14 seem to
have comparable values for the second reduction potential,
while trans-2 compound (ꢀ)-9 is again easier to reduce to
its corresponding dianion. The first reduction potentials E 11=2
are all more negative than that of the non-tethered trans-1
reference bisadduct 24 (Table 1).[15a] It thus appears as if the
tethers in all cases, including those on the dibenzo[18]crown
derivative analogues (ꢀ)-25 and (ꢀ)-26 (Figure 8), result in
cathodic shifts for the first reduction potential, expected if
they all exhibit some intramolecular donor–acceptor interac-
tions.
building blocks for supramolecular applications.[25] To the
best of our knowledge, there are no other examples of asym-
metric syntheses using the structural motif of the Trçger
base as a chiral auxiliary. In addition, we describe the use of
derivatives of the Trçger base in the regio- and diastereose-
lective (with respect to in–out isomerism) tether-directed
remote functionalization to give trans-4 and trans-1 bisad-
ducts of C60 in remarkably high yields. Spontaneous resolu-
tion of the trans-1 derivative afforded the enantiomer in
which the fullerene sphere is bridged by an (R,R)-config-
ured Trçger base tether as shown by X-ray crystallography:
it is the first such example in the field of fullerene chirality.
We are now applying the novel tethers to the regio- and
stereoselective multiple functionalization of higher fuller-
enes, a nearly unexplored field.[26]
To further probe the stability of these compounds upon
electron reductions, CPEs were performed for (ꢀ)-9,
(ꢀ)-14, and (ꢀ)-19 (see Supporting Information for details).
While CV showed that the trans-1 bisadduct (ꢀ)-19 is kinet-
ically much more stable than (ꢀ)-9 and (ꢀ)-14, even after
two-electron reduction, CPE resulted in the decomposition
of all adducts back to the parent C60. Thus on the CV time
scale (seconds), trans-1 bisadduct (ꢀ)-19 is more stable than
the others when reduced, but all three bisadducts are unsta-
ble on the CPE time scale (minutes).
Experimental Section
General methods: All chemicals and solvents were obtained from com-
mercial sources (Fluka, Aldrich, Merck) and used without further purifi-
cation unless stated otherwise. Technical grade solvents were distilled
before use. THF was distilled over sodium/benzophenone. DMF was
stored over flame-dried molecular sieves (4 ꢃ). Reactions were carried
out under dry N2 or Ar. TLC: precoated SiO2 plates Alugram UV254 (Ma-
cherey-Nagel). Column chromatography: Kieselgel 60 (Fluka, particle
size 0.040–0.063 mm). HPLC: Merck-Hitachi L-6250 Intelligent Pump, L-
4000 A UV-detector, and D-2500 Chromato-Integrator. FT-IR spectra:
1
Perkin Elmer Spectrum BX Spectrometer. NMR: 300 MHz H NMR and
75 MHz 13C NMR spectra were recorded on a Varian Gemini 300 spec-
trometer; 500 MHz 1H NMR and 125 MHz 13C NMR spectra were mea-
sured on a Bruker AMX 500 spectrometer; chemical shifts (d) are given
in ppm relative to TMS; coupling constants (J) are given in Hz; solvent
signals were used as internal references. EI-MS (70 eV): Micromass
Auto-Spec Ultima mass spectrometer; ESI-MS (solvent CH2Cl2/CH3OH)
and MALDI-MS (2-[(2E)-3-(4-tert-butylphenyl)-2-methylprop-2-enylide-
ne]malononitrile (DCTB) matrix): Ion Spec 4.7 Ultima mass spectrome-
ter. UV-visible spectra: Varian CARY 500 spectrophotometer. Circular
Conclusion
In this paper, we report the first diastereoselective synthesis
of enantiomeric bisadducts of C60 with the inherently chiral
trans-2 and trans-3 addition patterns by tether-directed
remote functionalization using novel Trçger base derivatives
as optically active spacers. Now, all inherently chiral bisaddi-
Figure 8. Reference compounds for electrochemical studies: non-tethered trans-1 bisadduct 24 and trans-1 and trans-2 bisadducts (ꢀ)-25 and (ꢀ)-26 with
crown ether spacers.
2290
ꢂ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 2284 – 2294

Bisadducts of C60
FULL PAPER
dichroism (CD) spectra: Jasco J 715 spectropolarimeter. Optical rota-
tions: Perkin-Elmer 241 polarimeter, [a]D values are given in
10ꢁ1 degcm2 gꢁ1. Melting points: Bꢁchi B-540 instrument in open capilla-
ries.
OCH2); 4.17 (s, 2H; NCH2N), 4.02 ppm (d, J=16.8 Hz, 2H; endo-
CH2N); 13C NMR (75 MHz, CDCl3/CD3OD): d=146.05, 137.02, 127.10,
126.17, 125.36, 124.57, 66.54, 63.85, 58.48 ppm; FT-IR (neat): n˜ =3410,
3150, 2920, 2872, 1612, 1576, 1492, 1205, 1008, 841, 831 cmꢁ1; HR-
MALDI-MS: m/z: calcd for C17H19N2O2 ([MH]+): 283.1447; found:
283.1437.
(ꢀ)-2,8-Diiodo-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine
((ꢀ)-
5):[12b] A mixture of 4 (6.59 g, 30 mmol) and paraformaldehyde (1.81 g,
60 mmol) was added in portions under vigorous stirring to TFA (50 mL)
at ꢁ158C. The resulting mixture was allowed to reach room temperature
and stirred for 40 h, then slowly added to a stirred mixture of ice and an
excess of concentrated aqueous NH3. Extraction with CH2Cl2 (3ꢄ
100 mL), drying of the organic layer over MgSO4, and removal of the sol-
vent in vacuo gave a crude product which was purified by flash chroma-
tography (AcOEt/CH2Cl2 1:10) to give (ꢀ)-5 (3.98 g, 56%). Rf (AcOEt/
(ꢀ)-(4,10-Dimethyl-7-hydroxymethyl-6H,12H-5,11-methanodibenzo[b,f]
[1,5]diazocin-1-yl)methanol ((ꢀ)-12): Prepared as described for (ꢀ)-3
from (ꢀ)-11 (367 mg, 1.2 mmol). Yield 338 mg (91%); m.p. 222–2238C;
1H NMR (300 MHz, CDCl3/CD3OD): d=6.99 (d, J=8.2 Hz, 2H; Ar-H),
6.85 (d, J=8.2 Hz, 2H; Ar-H), 4.50 (d, J=17.5 Hz, 2H; exo-CH2N), 4.37
(s, 4H; OCH2), 4.16 (s, 2H; NCH2N), 4.11 (d, J=17.5 Hz, 2H; endo-
CH2N), 2.61 (br. s, 2H; OH), 2.38 ppm (s, 6H; CH3); 13C NMR (75 MHz,
CDCl3/CD3OD): d=145.94, 135.19, 132.45, 128.67, 126.21, 123.30, 66.33,
61.98, 52.47, 17.29 ppm; FT-IR (neat): n=3550–3260 (OH), 2863, 1579,
1446, 1407, 1217, 977, 942, 817 cmꢁ1; HR-MALDI-MS: m/z: calcd for
C19H23N2O2 ([MH]+): 311.1760; found: 311.1754.
1
CH2Cl2 1:10)=0.26 ; m.p. 178.5–1808C; H NMR (300 MHz, CDCl3): d=
7.45 (dd, J=8.4, J=1.9 Hz, 2H; Ar-H), 7.23 (d, J=1.9 Hz, 2H; Ar-H),
6.87 (d, J=8.4 Hz, 2H; Ar-H), 4.62 (d, J=16.8 Hz, 2H; exo-CH2N), 4.24
(s, 2H; NCH2N), 4.08 ppm (d, J=16.8 Hz, 2H; endo-CH2N); 13C NMR
(75 MHz, CDCl3): d=147.47, 136.34, 135.63, 130.07, 126.93, 87.60, 66.54,
58.16 ppm; ESI-MS: 475 (100, [MH]+), 497 (9, [M+Na]+).
(6-Aminonaphthyl)methanol (16): Acid 15 (1.87 g, 10 mmol) was added
in portions to a suspension of LiAlH4 (1.14 g, 30 mmol) in dry THF
(50 mL) at 08C. After the addition was completed, the mixture was stir-
red for 1 h at room temperature and then heated to reflux for 2 h. The
mixture was allowed to reach room temperature and carefully quenched
by slow addition of water. The inorganic precipitate was filtered and the
filtrate dried over MgSO4 and concentrated to give 16 (1.61 g, 93%) as a
slightly brownish solid which was used without further purification; m.p.
(ꢀ)-1,7-Diiodo-4,10-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]di-
azocine ((ꢀ)-7): Prepared as described for (ꢀ)-5 from
6 (4.46 g,
19.1 mmol). Yield 3.72 g (77%); Rf =0.67 (CH2Cl2); m.p. 208.5–210.08C;
1H NMR (300 MHz, CDCl3): d=7.44 (d, J=8.1 Hz, 2H; Ar-H), 6.81 (d,
J=7.8 Hz, 2H; Ar-H), 4.25 (d, J=17.1 Hz, 2H; exo-CH2N), 4.20 (s, 2H;
NCH2N), 3.84 (d, J=17.1 Hz, 2H; endo-CH2N), 2.42 ppm (s, 6H; CH3);
13C NMR (75 MHz, CDCl3): d=147.71, 134.32, 133.63, 130.66, 129.84,
95.33, 66.91, 61.24, 17.20 ppm; FT-IR (neat): n˜ =2937, 2879, 1571, 1446,
1426, 1389, 1211, 1118, 963, 939, 798 cmꢁ1; HR-ESI-MS: m/z: calcd for
C17H17I2N2 ([MH]+): 502.9481; found: 502.9468.
1
166–1688C (decomp); H NMR (300 MHz, (CD3)2SO): 7.53–7.57 (m, 2H;
Ar-H), 7.46 (d, J=8.4 Hz, 1H; Ar-H), 7.25 (dd, J=8.4, 1.6 Hz, 1H; Ar-
H), 6.92 (dd, J=8.7, 2.2 Hz, 1H; Ar-H), 6.81 (d, J=2.2 Hz, 1H; Ar-H),
5.30 (s, 2H; CH2), 5.15 (br. s, 1H; OH), 4.53 ppm (s, 2H; NH2);
13C NMR (75 MHz, (CD3)2SO): d=146.11, 134.67, 133.93, 128.17, 125.91,
125.40, 124.28, 124.55, 118.25, 105.83, 63.21 ppm; FT-IR (neat): n˜ =3370
(NH2), 3195 (OH), 2923, 2863, 1630, 1607, 1508, 1483, 1178, 1011, 882,
821 cmꢁ1; HR-EI-MS: m/z: calcd for C11H11NO ([M]+): 173.0841; found:
173.0835.
(ꢀ)-6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine-2,8-dicarbaldehyde
((ꢀ)-8):[12a] A solution of (ꢀ)-5 (474 mg, 1.0 mmol) in dry THF (5 mL)
was treated dropwise with a 1.6m solution of nBuLi in hexane (1.6 mL,
2.5 mmol) at ꢁ808C. The mixture was stirred for 5 min at ꢁ788C, then
dry DMF (0.2 mL, 2.6 mmol) was added. The mixture was allowed to
reach room temperature, then water (10 mL) was added. Extraction with
CH2Cl2 (3ꢄ25 mL), drying of the organic layer over MgSO4 and removal
of the solvent in vacuo gave a crude product which was purified by flash
chromatography (AcOEt/CH2Cl2 1:3) to give (ꢀ)-8 (253 mg, 91%). Rf =
0.39 (AcOEt/CH2Cl2 1:3); m.p. 161–1628C; 1H NMR (300 MHz, CDCl3):
d=9.83 (s, 2H; CHO), 7.69 (dd, J=8.4, J=1.5 Hz, 2H; Ar-H), 7.47 (d,
J=1.5 Hz, 2H; Ar-H), 7.27 (d, J=8.4 Hz, 2H; Ar-H), 4.81 (d, J=
16.8 Hz, 2H; exo-CH2N), 4.29–4.36 ppm (m, 4H; NCH2N, endo-CH2N);
13C NMR (75 MHz, CDCl3): d=190.76, 153.80, 132.41, 128.99, 128.90,
128.00, 125.50, 66.49, 58.65 ppm; ESI-MS: 279 ([MH]+).
(ꢀ)-(11-Hydroxymethyl-8H,16H-7,15-methanodinaphtho[2,1-b][2’,1’-f]
[1,5]-diazocin-3-yl)methanol ((ꢀ)-17):
A suspension of 16 (865 mg,
5.0 mmol) in EtOH (10 mL) was treated at 08C first with formaldehyde
solution (37% in water; 2.5 mL, ca. 30 mmol) and then with concentrated
HCl solution (32% in water, 2.0 mL). After stirring at room temperature
for 2 h, the mixture turned to clear yellow solution, then a white solid
precipitated slowly. After 16 h, water (30 mL) was added and the pH ad-
justed to 14 with conc. aqueous NH3. The formed precipitate was filtered,
washed excessively with H2O, then with CH2Cl2, and dried in vacuo to
give (ꢀ)-17 (736 mg, 77%) which was used without further purification.
M.p.: decomposes above 2908C; 1H NMR (300 MHz, (CD3)2SO): 7.63–
7.72 (m, 6H; Ar-H), 7.42 (d, J=8.6 Hz, 2H; Ar-H), 7.35 (d, J=8.7 Hz,
2H; Ar-H), 5.26 (t, J=5.6 Hz, 2H; OH), 4.94 (d, J=16.8 Hz, 2H; exo-
CH2N), 4.69 (d, J=16.8 Hz, 2H; endo-CH2N), 4.58 (d, J=5.6 Hz, 4H;
CH2OH), 4.42 ppm (s, 2H; NCH2N); 13C NMR (75 MHz, (CD3)2SO): d=
144.80, 138.57, 129.89, 129.76, 126.92, 125.45, 124.79, 124.54, 121.14,
121.03, 66.01, 62.69, 55.15 ppm; FT-IR (neat): n˜ =3360–3180 (OH), 2909,
2847, 1597, 1471, 1389, 1210, 1017, 935, 896, 821 cmꢁ1; ESI-MS: 383
([MH]+); HR-MALDI-MS: m/z: calcd for C25H23N2O2 ([MH]+):
383.1760; found: 383.1759.
(ꢀ)-4,10-Dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine-1,7-
dicarbaldehyde ((ꢀ)-11): Prepared as described for (ꢀ)-8 from (ꢀ)-7
(502 g, 1.0 mmol) with the following amendment: 50 mL THF was used
due to limited solubility of (ꢀ)-7 at low temperature. Yield 241 mg
(79%); Rf =0.26 (AcOEt/CH2Cl2 1:20); m.p. 240–2428C (decomp);
1H NMR (300 MHz, CDCl3): d=9.90 (s, 2H; CHO), 7.40 (d, J=8.1 Hz,
2H; Ar-H), 7.27 (d, J=8.1 Hz, 2H; Ar-H), 4.82 (d, J=18.0 Hz, 2H; exo-
CH2N), 4.59 (d, J=18.0 Hz, 2H; endo-CH2N), 4.27 (s, 2H; NCH2N),
2.54 ppm (s, 6H; CH3); 13C NMR (75 MHz, CDCl3): d=192.94, 147.20,
140.63, 131.47 (2 overlapped signals), 130.06, 129.09, 65.62, 54.47,
18.39 ppm; FT-IR (neat): n˜ =2894, 2729, 1678 (C=O), 1568, 1426, 1218,
1100, 950, 935, 820, 751 cmꢁ1; ESI-MS: m/z: 307 (55, MH+), 279 (100,
[MHꢁCO]+). HR-MALDI-MS: m/z: calcd for C19H19N2O2 ([MH]+):
307.1447; found: 307.1445.
(ꢀ)-Diethyl 4,4’-(6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine-2,8-
diyl)dibenzoate ((ꢀ)-20): A suspension of 4-(ethoxycarbonyl)phenylbor-
onic acid (1.076 g, 5.55 mmol) in ethanol (8 mL) and a solution of K2CO3
(3.317 g, 24.00 mmol) in H2O (4 mL) were added to a solution of (ꢀ)-3
(948 mg, 2.00 mmol) and [Pd(PPh3)4] (231 mg, 0.20 mmol) in toluene
(40 mL). The resulting mixture was heated to reflux for 1.5 h under Ar,
then cooled to room temperature and partitioned between CH2Cl2
(100 mL) and H2O (50 mL). The organic layer was separated, washed
with H2O (2ꢄ50 mL), dried over MgSO4, and concentrated in vacuo.
Flash chromatography (AcOEt/CH2Cl2 1:10–1:5) afforded (ꢀ)-20
(835 mg, 81%) as colorless solid. Rf (AcOEt/CH2Cl2 1:5)=0.24; m.p.
209–2118C; 1H NMR (300 MHz, CDCl3): d=8.05 (d, J=8.7 Hz, 4H; Ar-
H), 7.54 (d, J=8.7 Hz, 4H; Ar-H), 7.44 (dd, J=8.4 Hz, 2.2, 2H; Ar-H),
7.25 (d, J=8.4 Hz, 2H; Ar-H), 7.19 (d, J=1.9 Hz; 2H; Ar-H), 4.81 (d,
(ꢀ)-(8-Hydroxymethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocin-
2-yl)-methanol ((ꢀ)-3): A solution of (ꢀ)-8 (556 g, 2.0 mmol) in dry
THF (20 mL) was slowly added to a suspension of LiAlH4 (114 mg,
3.0 mmol) in dry THF (20 mL). The mixture was stirred for 2 h at room
temperature, then quenched by slow addition of water. The inorganic
precipitate was filtered and the filtrate dried over MgSO4 and concentrat-
ed to give (ꢀ)-3 (524 mg, 93%) which was used without further purifica-
tion. M.p. 194.5–196.58C; 1H NMR (300 MHz, CDCl3/CD3OD): d=7.02
(dd, J=8.4 Hz, 1.9, 2H; Ar-H), 6.97 (d, J=8.4 Hz, 2H; Ar-H), 6.76 (d,
J=1.9 Hz, 2H; Ar-H), 4.52 (d, J=16.8 Hz, 2H; exo-CH2N), 4.35 (s, 4H;
Chem. Eur. J. 2005, 11, 2284 – 2294
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ꢂ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
2291

F. Diederich et al.
2H, J=16.5 Hz, 2H; exo-NCH2), 4.39 (s, 2H; NCH2N)), 4.38 (q, J=
7.2 Hz, 4H; CH3CH2), 4.31 (d, J=16.8, 2H; endo-NCH2), 1.40 ppm (t,
J=7.2 Hz, 6H; CH3CH2); 13C NMR (75 MHz, CDCl3): d=166.33, 148.10,
144.76, 135.72, 129.94, 128.87, 128.18, 126.51, 126.32, 125.70, 125.51, 67.00,
61.00, 58.90, 14.51 ppm; FT-IR (neat): n˜ =2956, 2898, 1705 (C=O), 1606,
CH3CH2), 3.42 (s, 4H; COCH2), 1.24 ppm (t, J=7.2 Hz, 6H; CH3);
13C NMR (75 MHz, CDCl3): d=166.33, 166.27, 147.55, 140.73, 136.32,
133.90, 128.71, 128.09, 126.91, 126.15, 125.44, 66.96, 61.65, 58.85, 41.72,
14.18 ppm; FT-IR (neat): n˜ =2963, 2925, 1723 (C=O), 1612, 1485, 1191,
1149, 1024, 826, 816 cmꢁ1; ESI-MS: 663 (100, [MH]+), 685 (39, [M+Na]+);
HR-ESI-MS: m/z: calcd for C39H39N2O8 ([MH]+): 663.2706; found:
663.2702.
1267, 1180, 1102, 962, 942, 747 cmꢁ1
; HR-ESI-MS: m/z: calcd for
C33H30N2NaO4 ([M+Na]+): 541.2103; found: 541.2098.
(ꢀ)-[6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine-2,8-diylbis(4,1-
(R,R)-22 and (S,S)-22 were isolated by preparative HPLC on a Regis
(S,S)-Whelk-O1 column (250ꢄ10 mm, eluent hexane/AcOEt/EtOH
83:5:12, flow rate 7 minꢁ1, detection at 290 nm). (R,R)-22: [a]D =ꢁ434
(c=0.80, chloroform); (S,S)-22: [a]D =+456 (c=0.76, chloroform).
phenylene)]dimethanol ((ꢀ)-21):
A
solution of (ꢀ)-20 (835 mg,
1.6 mmol) in THF (20 mL) was added dropwise to a suspension of
LiAlH4 (190 mg, 5.0 mmol) in THF (10 mL). The mixture was heated to
reflux for 2 h under Ar, then cooled to 08C and carefully quenched by
slow addition of water. The inorganic precipitate was filtered and the fil-
trate dried over MgSO4 and evaporated in vacuo to give (ꢀ)-21 (700 mg,
100%) which was used without further purification. M.p. 243.5–2458C.
1H NMR (300 MHz, (CD3)2SO): d=7.50 (d, J=8.4 Hz, 4H; Ar-H), 7.42
(dd, J=8.4 Hz, 2.2, 2H; Ar-H), 7.33 (d, J=8.4 Hz, 4H; Ar-H), 7.25 (d,
J=1.9 Hz, 2H; Ar-H), 7.19 (d, J=8.4 Hz, 2H; Ar-H), 5.17 (t, J=5.8 Hz,
2H; OH), 4.70 (d, J=16.8 Hz, 2H; exo-NCH2), 4.49 (d, J=5.9 Hz, 4H;
CH2O), 4.28 (s, 2H; NCH2N), 4.23 ppm (d, J=17.1 Hz, 2H; endo-
NCH2); 13C NMR (75 MHz, (CD3)2SO): d=147.28, 141.06, 138.03, 135.07,
128.33, 126.76, 125.79, 125.10, 125.03, 124.69, 66.22, 62.55, 58.24 ppm; FT-
IR (neat): n˜ =3250 (OH), 2950, 2899, 2848, 1611, 1479, 1320, 964, 941,
841, 764 cmꢁ1; ESI-MS: m/z (%): 435 (100) ([MH]+), 457 (12) ([M+Na]+);
HR-ESI-MS: m/z: calcd for C29H27N2O2 ([MH]+): 435.2073; found:
435.2061.
(ꢀ)-1,1’-Diethyl 3,3’-(4,10-Dimethyl-6H,12H-5,11-Methanodibenzo[b,f]
[1,5]diazocine-1,7-diyl)dimethylene Dimalonate ((ꢀ)-13): Prepared as
described for (ꢀ)-2 from (ꢀ)-12 (310 mg, 1.0 mmol). Viscous colorless
oil, which crystallized very slowly upon standing; yield 288 mg (54%);
m.p. 92–93.58C; Rf (AcOEt/CH2Cl2 1:5)=0.32; 1H NMR (300 MHz,
CDCl3): d=7.08 (d, J=7.8 Hz, 2H; Ar-H), 7.00 (d, J=7.8 Hz, 2H; Ar-
H), 5.01 (s, 4H; OCH2Ar), 4.57 (d, J=17.1 Hz, 2H; exo-CH2N), 4.28 (s,
2H; NCH2N), 4.16 (qd, J=7.2, 2.0 Hz; 4H; CH2CH3), 4.06 (d, J=
17.1 Hz, 2H; endo-CH2N), 3.36 (s, 4H; CH2CO), 2.42 (s, 6H; CH3),
1.23 ppm (t, J=7.2 Hz, 6H; CH2CH3); 13C NMR (75 MHz, CDCl3): d=
166.17, 166.09, 146.40, 133.99, 129.52, 128.85, 127.03, 125.13, 66.35, 64.47,
61.61, 52.58, 41.56, 17.45, 14.11 ppm; FT-IR (neat): n˜ =2946, 2899, 1744
(C=O), 1728 (C=O), 1580, 1330, 1142, 1094, 1023, 977, 810, 747 cmꢁ1
;
HR-ESI-MS: m/z: calcd for C29H34N2O8Na ([M+Na]+): 561.2213; found:
561.2213.
(ꢀ)-1,1’-Diethyl 3,3’-(6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine-
2,8-diyl)dimethylene Dimalonate ((ꢀ)-2): A solution of (ꢀ)-3 (282 mg,
1.0 mmol) and DMAP (488 mg, 4.0 mmol) in dry THF (50 mL) was treat-
ed at 08C with EtOOCCH2COCl (0.50 mL; 4.0 mmol). The mixture was
stirred at room temperature for 16 h, then the solvent was removed in
vacuo. Column chromatography of the residue afforded (ꢀ)-2 (267 mg,
52%). Viscous colorless oil. Rf (AcOEt/CH2Cl2 1 : 2)=0.26; 1H NMR
(300 MHz, CDCl3): d=7.15 (dd, J=8.1 Hz, 1.9, 2H; Ar-H), 7.11 (d, J=
8.1 Hz, 2H; Ar-H), 6.90 (d, J=1.9 Hz, 2H; Ar-H), 5.03 (s, 4H; OCH2),
4.68 (d, J=16.8 Hz, 2H; exo-CH2N), 4.28 (s, 2H; NCH2N), 4.10–4.17 (m,
6H; endo-CH2N, CH2CH3), 3.36 (s, 4H; CH2CO), 1.20 ppm (t, J=7.2 Hz,
6H; CH2CH3); 13C NMR (75 MHz, CDCl3): d=166.23, 166.19, 148.11,
130.76, 127.77, 127.64, 127.17, 125.18, 66.89, 66.72, 61.55, 58.57, 41.61,
14.09 ppm; FT-IR (neat): n˜ =2980, 2945, 2900, 1742 sh, 1724 (C=O), 1616,
1493, 1326, 1263, 1204, 1143, 1029, 834 cmꢁ1; HR-ESI-MS: m/z: calcd for
C27H30N2O8Na ([M+Na]+): 533.1900; found: 533.1901.
out,out-3’,3’’-Diethyl
[1,5]diazocine-2,8-diyldimethylene)
pa[1,9:49,59](C60-Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate
out,out-3’,3’’-Diethyl (S,S)-3’,3’’-(6H,12H-5,11-Methanodibenzo[b,f]
(S,S)-3’,3’’-(6H,12H-5,11-Methanodibenzo[b,f]
(f,sA)-3’H,3’’H-Dicyclopro-
and
[1,5]diazocine-2,8-diyldimethylene) 3’H,3’’H-Dicyclopropa[1,9:16,17](C60-
Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate ((S,S,f,sA)-9 and (S,S)-10): A
well-degassed solution of (S,S)-2 (44 mg, 0.086 mmol) and C60 (54 mg,
0.075 mmol) in toluene (100 mL) was treated at 08C with a solution of I2
(48 mg, 0.19 mmol) in toluene (5 mL) and then with DBU (0.07 mL,
0.45 mmol). The resulting mixture was stirred for 1 h at 08C, then filtered
and applied on a SiO2 column. Elution with CH2Cl2/AcOEt 5:1 afforded
(S,S,f,sA)-9 (25 mg, 27%), then (S,S)-10 (5 mg, 6%). Analogously,
(R,R,f,sC)-9 (25%), and (R,R)-10 (6%) were prepared starting from
(R,R)-8.
(S,S,f,sA)-9: UV/Vis (CHCl3): lmax(e)=405 (sh, 4950), 432 (4000), 488
(2000), 636 (550), 701 nm (400); 1H NMR (300 MHz, CDCl3): d=7.28
(m, overlap with CHCl3, 2H, Ar-H), 6.99 (d, J=8.1, 2H; Ar-H), 6.94 (s,
2H; Ar-H), 5.87 (d, J=11.5 Hz, 2H; OCH2Ar), 4.96 (d, J=11.5 Hz, 2H;
OCH2Ar), 4.70 (q, J=7.2 Hz, 4H; CH2CH3), 4.59 (d, J=17.1 Hz, 2H;
NCH2Ar), 3.91 (s, 2H; NCH2N), 3.85 (d, J=17.1 Hz, 2H; NCH2Ar),
1.62 ppm (t, J=7.2 Hz, 6H; CH2CH3); 13C NMR (75 MHz, CDCl3): d=
164.04, 163.48, 149.65, 146.88, 146.87, 146.20, 145.98, 145.30, 145.23,
144.91, 144.85, 144.67, 144.59, 144.32, 144.00, 143.74, 143.40, 143.30,
143.14, 142.78, 142.16, 142.12, 142.04, 141.98, 141.88, 141.63, 141.31,
140.78, 139.75, 136.07, 135.24, 130.35, 129.33, 128.93, 127.95, 125.61, 70.89,
70.79, 67.84, 65.33, 63.76, 56.17, 49.06, 14.54 ppm; FT-IR (neat): n˜ =2975,
(R,R)-2 and (S,S)-2 were isolated by preparative HPLC on a Daicel Chir-
alcel OJ column (250ꢄ20 mm, eluent ethanol, flow rate 15 mLminꢁ1, de-
tection at 254 nm). (R,R)-2: [a]D =ꢁ195 (c=0.25, chloroform); (S,S)-2:
[a]D =+203 (c=0.48, chloroform).
(ꢀ)-1,1’-Diethyl
3,3’-(8H,16H-7,15-Methanodinaphtho[2,1-b][2ꢁ,1ꢁ-f]
[1,5]diazocin-3,11-diyl)dimethylene Dimalonate ((ꢀ)-18): Prepared as
described for (ꢀ)-2 from (ꢀ)-17 (382 mg, 1.0 mmol). Viscous colorless
oil. Yield 123 mg (20%); Rf (AcOEt/CH2Cl2 1:5)=0.20; 1H NMR
(300 MHz, CDCl3): d=7.64–7.71 (m, 6H; Ar-H), 7.42 (dd, J=8.6 Hz, 1.7,
2H; Ar-H), 7.35 (d, J=9.0 Hz, 2H; Ar-H), 5.27 (s, 4H; 2 OCH2Ar), 5.00
(d, J=16.8 Hz; 2H; exo-NCH2), 4.73 (d, J=16.8 Hz; 2H; endo-NCH2),
4.50 (s, 2H; NCH2N), 4.17 (q, J=7.2 Hz, 4H; CH2CH3), 3.40 (s, 4H;
COCH2), 1.22 ppm (t, J=7.2 Hz, 6H; CH3); 13C NMR (75 MHz, CDCl3):
d=166.26, 145.69, 131.48, 131.02, 130.44, 128.20, 127.83, 126.48, 121.64,
121.09, 67.17, 66.72, 61.58, 55.66, 41.65, 14.14 ppm; FT-IR (neat): n˜ =
2980, 2899, 1741 sh, 1725 (C=O), 1599, 1474, 1327, 1264, 1144, 1027, 819,
2878, 1739 (C=O), 1607, 1490, 1222, 1106, 1055, 942, 828, 734, 702 cmꢁ1
;
HR-MALDI-MS: m/z: calcd for C87H26N2O8 ([M]+): 1226.1689; found
1226.1696.
(S,S)-10: UV/Vis (CHCl3): lmax(e)=409 (sh, 2700), 422 (2300), 480 nm
(2670); 1H NMR (300 MHz, CDCl3): d=7.09–7.15 (m, 3H; Ar-H), 6.92
(s, 1H; Ar-H), 6.87(s, 1H; Ar-H), 6.76 (d, 1H; Ar-H), 5.67 (d, J=
11.0 Hz, 1H; OCH2Ar), 5.54 (d, J=13.2 Hz, 1H; OCH2Ar), 5.10 (d, J=
13.2 Hz, 1H; OCH2Ar), 5.01 (d, J=11.0 Hz, 1H; OCH2Ar), 4.40–4.63
(m, 6H, OCH2CH3, NCH2Ar), 4.30 (s, 2H; NCH2N), 4.14 (d, J=17.1 Hz,
1H; NCH2Ar), 3.68 (d, J=17.1 Hz, 1H; NCH2Ar), 1.39–1.46 (m, 6H,
OCH2CH3); 13C NMR (75 MHz, CDCl3): d=163.38, 163.06, 162.99,
162.27, 148.99, 148.42, 147.17, 147.10, 146.99, 146.91, 146.50, 146.29,
146.27, 146.16, 145.87, 145.85, 145.82, 145.47, 145.34, 144.92, 144.91,
144.85, 144.80, 144.69, 144.63, 144.51, 144.47, 144.43, 144.38, 144.31,
144.10, 143.79, 143.76, 143.63, 143.56, 143.54, 143.51, 143.50, 143.50,
143.50, 143.29, 143.15, 142.95, 142.67, 142.28, 142.10, 141.81, 141.73,
732 cmꢁ1
;
HR-MALDI-MS: m/z: calcd for C35H35N2O8 ([MH]+):
611.2393; found: 611.2378.
(ꢀ)-1,1’-Diethyl 3,3’-[6H,12H-5,11-Methanodibenzo[b,f][1,5]diazocine-
2,8-diylbis(4,1-phenylenemethylene)] Dimalonate ((ꢀ)-22): Prepared as
described for (ꢀ)-2 from (ꢀ)-21 (218 mg, 0.50 mmol). Yield 139 mg
(42%); Rf (AcOEt/CH2Cl2 1:2)=0.47; m.p. 123–1258C; 1H NMR
(300 MHz, CDCl3): d=7.48 (d, J=8.4 Hz, 4H; Ar-H), 7.36–7.42 (m, 6H;
Ar-H), 7.23 (d, J=8.4 Hz, 2H; Ar-H), 7.14 (d, J=1.9 Hz, 2H; Ar-H),
5.19 (s, 4H; CH2OAr), 4.80 (d, J=16.5 Hz, 2H; exo-NCH2), 4.38 (s, 2H;
NCH2N), 4.29 (d, J=16.8 Hz, 2H; endo-NCH2), 4.19 (q, J=7.2 Hz, 4H;
2292
ꢂ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 2284 – 2294

Bisadducts of C60
FULL PAPER
141.61, 141.53, 141.52, 141.45, 141.30, 140.64, 138.37, 138.17, 137.89,
137.83, 71.57, 71.28, 71.09, 68.54, 67.67, 66.99, 63.39, 63.34, 59.37, 58.89,
53.16, 51.19, 14.33 ppm; FT-IR (neat): n˜ =2976, 2898, 1738 (C=O), 1614,
1492, 1225, 1205, 1097, 1058, 831, 731, 701 cmꢁ1; HR-MALDI-MS: m/z:
calcd for C87H26N2O8 ([M]+): 1226.1689; found 1226.1672.
2.2 Hz, 1H; Ar-H), 7.24–7.31 (m, overlap with CHCl3, 3H; Ar-H), 7.21
(d, J=1.9 Hz, 1H; Ar-H), 7.14 (d, J=8.4 Hz, 1H; Ar-H), 7.02 (d, J=
8.1 Hz, 1H; Ar-H), 6.90 (d, J=1.9 Hz, 1H; Ar-H), 6.10 (d, J=10.6 Hz,
1H; OCH2Ar), 5.90 (d, J=10.9 Hz, 1H; OCH2Ar), 5.08 (d, J=10.6 Hz,
1H; OCH2Ar), 5.02 (d, J=10.9 Hz, 1H; OCH2Ar), 4.71 (d, J=16.2 Hz,
2H; exo-NCH2), 4.41–4.58 (m, 6H; CH3CH2, NCH2N), 4.16 (d, J=
16.5 Hz, 1H; endo-NCH2), 4.07 (d, J=16.5 Hz, 1H; endo-NCH2), 1.51 (t,
J=7.0 Hz, 3H; CH3CH2), 1.42 ppm (t, J=7.2 Hz, 3H; CH3CH2);
13C NMR (125 MHz, CDCl3): d=163.79, 163.52, 163.39, 162.57, 147.45,
147.38, 147.24, 146.86, 146.81, 146.65, 146.60, 146.52, 146.48, 146.35,
146.23, 145.67, 145.37, 145.34, 145.28, 145.24, 145.07, 144.96, 144.94,
144.86, 144.69, 144.50, 144.40, 144.35, 144.28, 144.23, 144.20, 143.96,
143.77, 143.43, 143.25, 143.24, 143.20, 143.14, 143.09, 142.81, 142.60,
142.59, 142.30, 141.87, 141.85, 141.80, 141.53, 141.36, 141.32, 141.23,
140.68, 140.59, 140.52, 140.24, 140.03, 139.65, 138.94, 137.80, 136.11,
135.41, 135.35, 133.97, 133.79, 132.33, 131.30, 129.04, 129.00, 128.61,
128.51, 128.23, 128.05, 127.36, 126.82, 126.49, 126.29, 126.02, 125.31,
124.80, 124.61, 71.68, 71.56, 71.00, 70.86, 69.36, 68.45, 67.56, 63.49, 63.44,
60.64, 59.86, 51.54, 51.30, 14.29, 14.19 ppm (1 C missing due to signal
overlap); FT-IR (neat): n˜ =2961, 2848, 1742 (C=O), 1607, 1485, 1246,
1227, 1207, 962, 753 cmꢁ1; HR-MALDI-MS: m/z: calcd for C99H34N2O8
([M]+): 1378.2315; found 1378.2295.
(S,S,f,sC)-23b: Retention time (analytical HPLC): 23.6 min; Rf (AcOEt/
CH2Cl2 1:10)=0.20; UV/Vis (CHCl3): lmax(e)=413 (2400), 423 (1950),
491 (1700), 620 nm (420); 1H NMR (300 MHz, CDCl3): d=7.58 (d, J=
8.5 Hz, 2H; Ar-H), 7.02–7.47 (m, overlap with CHCl3, 11H; Ar-H), 6.87
(d, J=1.9 Hz, 1H; Ar-H), 5.80 (d, J=11.0 Hz, 1H; OCH2Ar), 5.70 (d,
J=11.0 Hz, 1H; OCH2Ar), 5.45 (d, J=10.7 Hz, 1H; OCH2Ar), 5.07 (d,
J=11.0 Hz, 1H; OCH2Ar), 4.68 (d, J=16.8 Hz, 2H; exo-NCH2), 4.43–
4.58 (m, 6H; CH3CH2, NCH2N), 4.13 (d, J=16.5 Hz, 1H; endo-NCH2),
3.94 (d, J=16.5 Hz, 1H; endo-NCH2), 1.49 (t, J=7.1 Hz, 3H; CH3CH2),
1.43 ppm (t, J=7.1 Hz, 3H; CH3CH2); FT-IR (neat): n˜ =2921, 2850, 1741
(C=O), 1610, 1485, 1226, 1207, 1174, 1103, 962, 771, 753 cmꢁ1; HR-
MALDI-MS: m/z: calcd for C99H34N2O8 ([M]+): 1378.2315; found
1378.2329.
out,out-3’,3’’-Diethyl (ꢀ)-3’,3’’-(4,10-Dimethyl-6H,12H-5,11-methanodi-
benzo[b,f][1,5]diazocine-1,7-diyldimethylene)
3’H,3’’H-Dicyclopro-
pa[1,9:32,33](C60-Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate
((ꢀ)-14):
Prepared as described for (S,S,f,sA)-9 from (ꢀ)-13 (129 mg, 0.24 mmol).
Yield 95 mg (38%); UV/Vis (CHCl3): lmax(e)=416 (2900), 472 (2100),
628 (470), 692 nm (310); 1H NMR (300 MHz, CDCl3): d=6.96 (d, J=
7.8 Hz, 1H; Ar-H), 6.84–6.89 (m, 2H; Ar-H), 6.74 (d, J=7.6 Hz, 1H; Ar-
H), 5.70 (d, J=11.5 Hz, 1H; OCH2Ar), 5.42 (d, J=11.8 Hz, 1H;
OCH2Ar), 5.26 (d, J=11.8 Hz, 1H; OCH2Ar), 4.88–4.97 (m, 2H;
NCH2Ar, OCH2Ar), 4.51–4.70 (m, 6H; CH2CH3, NCH2Ar), 4.24 (d, J=
16.5 Hz, 1H; NCH2Ar), 4.14 (s, 2H; NCH2N), 2.48 (s, 3H; CH3-Ar), 2.26
(s, 3H; CH3-Ar), 1.51 ppm (t, J=7.1 Hz, 6H; CH2CH3); 13C NMR
(75 MHz, CDCl3): d=163.52, 163.33, 163.17, 163.00, 147.91, 146.85,
146.78, 146.06, 145.93, 145.88, 145.78, 145.64, 145.35, 145.31, 145.24,
145.09, 145.06, 144.93, 144.88, 144.82, 144.76, 144.71, 144.50, 144.32,
143.95, 143.91, 143.83, 143.78, 143.77, 143.14, 142.99, 142.91, 142.81,
142.75, 142.58, 142.56, 142.41, 141.99, 141.86, 141.85, 141.64, 141.58,
141.50, 141.18, 141.11, 141.03, 140.97, 140.73, 140.61, 140.13, 139.45,
139.19, 138.92, 138.42, 138.15, 134.32, 134.27, 133.96, 133.30, 129.04,
129.00, 128.94, 128.83, 127.46, 126.71, 125.84, 125.25, 70.94, 70.75, 70.53,
70.22, 66.41, 63.64, 63.40, 62.17, 52.68, 52.25, 50.21, 49.23, 17.60, 17.51,
14.54 ppm; FT-IR (neat): n˜ =2956, 2889, 1732 (C=O), 1442, 1365, 1223,
1093, 1060, 805 cmꢁ1; HR-MALDI-MS: m/z: calcd for C89H30N2O8 ([M]+):
1254.2002; found 1254.1986.
out,out-3’,3’’-Diethyl (ꢀ)-3’,3’’-(8H,16H-7,15-methanodinaphtho[2,1-b]
[2ꢁ,1ꢁ-f][1,5]diazocin-3,11-diyldimethylene)
3’H,3’’H-Dicyclopropa-
[1,9:52,60](C60-Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate ((ꢀ)-19): Pre-
pared as described for (S,S,f,sA)-9 from (ꢀ)-18 (121 mg, 0.20 mmol) with
the following amendment: acylation was performed in DMF (5 mL).
Yield 128 mg (58%); UV/Vis (CHCl3): lmax(e)=405 (sh, 4950), 440
(2500), 470 (3700), 575 (sh, 500), 650 nm (sh, 200); 1H NMR (300 MHz,
CDCl3): d=7.93 (s, 2H; Ar-H), 7.56–7.62 (m, 6H, Ar-H), 7.29 (d, J=
8.7 Hz, 2H; Ar-H), 5.89 (d, J=10.9 Hz, 2H; OCH2Ar), 5.70 (d, J=
10.9 Hz, 2H; OCH2Ar), 5.00 (d, J=17.1 Hz, 2H; NCH2Ar), 4.65 (q, J=
7.2 Hz, 4H; OCH2CH3), 4.48 (d, J=17.1 Hz, 2H; NCH2Ar), 4.33 (s, 2H;
NCH2N), 1.58 ppm (t, J=7.2 Hz, 6H; CH3); 13C NMR (75 MHz, CDCl3):
d=164.27, 164.15, 147.24, 145.09, 145.02, 144.93, 144.45, 144.38, 143.88,
143.61, 143.30, 143.09, 143.01, 142.98, 142.83, 142.77, 142.73, 142.57,
142.41, 142.11, 142.09, 142.00, 141.82, 140.90, 140.73, 140.58, 140.56,
140.44, 140.13, 136.34, 135.91, 132.24, 131.91, 131.53, 131.18, 129.25,
128.48, 125.65, 121.76, 121.47, 69.73, 69.65, 69.08, 65.81, 63.65, 54.88,
44.83, 14.46 ppm; FT-IR (neat): n˜ =2920, 2850, 1727 (C=O), 1596, 1470,
X-ray crystal structure analyses: (ꢀ)-13: Crystal data at 220(2) K:
¯
C29H34N2O8, Mr =538.58, triclinic, space group P1 (no. 2), 1calcd
=
1.341 gcmꢁ3
, Z=2, a=8.3728(2), b=12.3137(2), c=13.5893(3) ꢃ, a=
106.060(1), b=97.703(1), g=98.613(1)8, V=1334.29(5) ꢃ3. Bruker-
Nonius CCD diffractometer, MoKa radiation, l=0.7107 ꢃ. A colorless
crystal was obtained by very slow evaporation of a solution of (ꢀ)-13 in
CH2Cl2. The structure was solved by direct methods (SIR97)[27] and re-
fined by full-matrix least-squares analysis (SHELXL-97),[28] using an iso-
tropic extinction correction, and w=1/[s2(Fo2) + (0.1092P)2 + 0.5140P],
where P=(F2o + 2F2c)/3. C29 is disordered over two orientations, only
one orientation is shown (see Supporting Information). All heavy atom
were refined anisotropically, hydrogen atoms isotropically, whereby hy-
drogen positions are based on stereochemical considerations. Final
R(F)=0.060, wR(F2)=0.171 for 385 parameters and 5036 reflections with
I>2s(I) and 3.14<q<27.47o (corresponding R values based on all 5897
reflections are 0.069 and 0.181 respectively).
1362, 1237, 1207, 1165, 1065, 1013, 806, 734 cmꢁ1
(DCTB): m/z: calcd for C95H30O8N2 ([M]+): 1326.2002; found: 1326.1980.
; HR-MALDI-MS
in,out-3’,3’’-Diethyl
(S,S)-3’,3’’-[6H,12H-5,11-Methanodibenzo[b,f]
[1,5]diazocine-2,8-diylbis(4,1-phenylenemethylene)] (f,sA)-3’H,3’’H-Dicy-
clopropa[1,9:34,35](C60-Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate and
(R,R)-19: Crystal data at 238(2) K: C95H30O8N2·2CH2Cl2, orthorhombic,
space group P212121 (no.19), 1calcd =1.625 gcmꢁ3, Z=4, a=10.3913(13),
b=23.387(8), c=25.187(7) ꢃ, V=6121(3) ꢃ3. Nonius CAD4 diffractome-
ter, CuKa radiation, l=1.5418 ꢃ. A black crystal was obtained by very
slow evaporation of a solution of (ꢀ)-19 in a mixture of CH2Cl2 and
CHCl3. It was cut to linear dimensions of about 0.32ꢄ0.25ꢄ0.22 mm and
mounted at low temperature to prevent evaporation of enclosed solvents.
The structure was solved by direct methods (SIR97)[27] and refined by
full-matrix least-squares analysis (SHELXL-97),[28] using an isotropic ex-
tinction correction, and w=1/[s2(Fo2) + (0.1932P)2 + 2.4285P], where
P=(F2o + 2F2c)/3. One of the two CH2Cl2 molecules, included in the crys-
tal packing, is disordered over four orientations. All heavy atoms of
(R,R)-19 were refined anisotropically, hydrogen atoms isotropically,
whereby hydrogen positions are based on stereochemical considerations.
Final R(F)=0.078, wR(F2)=0.209 for 1050 parameters and 4485 reflec-
tions with I>2s(I) and 2.58<q<66.968 (corresponding R values based
on all 5751 reflections are 0.098 and 0.242, respectively).
in,out-3’,3’’-Diethyl
(S,S)-3’,3’’-[6H,12H-5,11-Methanodibenzo[b,f]
[1,5]diazocine-2,8-diylbis(4,1-phenylenemethylene)] (f,sC)-3’H,3’’H-Dicy-
clopropa[1,9:34,35](C60-Ih)[5,6]fullerene-3’,3’,3’’,3’’-tetracarboxylate
((S,S,f,sA)-23a and (S,S,f,sC)-23a): Prepared as described for (S,S,f,sA)-9
from (S,S)-22. Column chromatography (AcOEt/CH2Cl2 1:10) afforded a
mixture of diastereoisomers which were separated by preparative HPLC
on a Regis Bucky Clutcher column (500ꢄ21 mm, eluent toluene/AcOEt
93 : 7, flow rate 15 minꢁ1, detection at 350 nm), to give (S,S,f,sA)-23a
(16.5 mg, 27%) and (S,S,f,sC)-23a (4.5 mg, 5%). Similarly, (R,R,f,sC)-23b
and (R,R,f,sA)-23b were prepared starting from (R,R)-22.
(S,S,f,sA)-23a: Retention time (analytical HPLC: Regis Bucky Clutcher
column, 250ꢄ4.6 mm, eluent toluene/AcOEt 93 : 7, flow rate 1 mLminꢁ1
,
detection at 350 nm): 19.9 min; Rf (AcOEt/CH2Cl2 1:10)=0.20; UV/Vis
(CHCl3): lmax(e)=413 (2480), 423 (2010), 490 (1680), 618 nm (440);
1H NMR (500 MHz, CDCl3): d=7.60 (d, J=8.4 Hz, 2H), 7.53 (d, J=
8.4 Hz, 2H; Ar-H), 7.43 (d, J=8.1 Hz, 2H; Ar-H), 7.37 (dd, J=8.4,
Chem. Eur. J. 2005, 11, 2284 – 2294
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2293

F. Diederich et al.
(ꢀ)-22: Crystal data at 200(2) K: C39H38N2O8, Mr =662.71, monoclinic,
space group C2/c (no.15), 1calcd =1.343 gcmꢁ3, Z=4, a=25.1985(6), b=
5.5400(1), c=23.6427(5) ꢃ, b=96.801(1)8, V=3277.29(12) ꢃ3. Bruker-
Nonius Kappa-CCD diffractometer, MoKa radiation, l=0.7107 ꢃ. A col-
orless crystal (linear dimensions about 0.25ꢄ0.21ꢄ0.15 mm) was ob-
tained by slow diffusion of hexane into solution of (ꢀ)-22 in CH2Cl2. The
structure was solved by direct methods (SIR97)[27] and refined by full-
matrix least-squares analysis (SHELXL-97),[28] using an isotropic extinc-
tion correction, and w=1/[s2(F2o) + (0.0718P)2 + 5.7134P], where P=
(F2o + 2F2c)/3. All heavy atoms of (ꢀ)-22 were refined anisotropically,
hydrogen atoms isotropically, whereby hydrogen positions are based on
stereochemical considerations. Final R(F)=0.061, wR(F2)=0.153 for 240
parameters and 2953 reflections with I>2s(I) and 3.26<q<27.47o (cor-
responding R values based on all 3726 reflections are 0.077 and 0.165, re-
spectively).
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CCDC-257155 ((ꢀ)-13), CCDC-257156 ((R,R)-19), and CCDC-257157
((ꢀ)-22) contain the supplementary crystallographic data for this paper.
These data can be obtained free of charge from The Cambridge Crystal-
lographic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Cyclic voltammetry: Electrochemical measurements were performed at
room temperature in a three-electrode cell containing 0.1m Bu4NPF6) in
CH2Cl2. A mini-glassy carbon electrode (CHI, 1 mm diameter) was used
as the working electrode, platinum wire was used as the counter elec-
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internal standard, and all potentials were measured relative to the Fc/Fc+
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Acknowledgements
We thank Dr. Carlo Thilgen for valuable discussions and for help with
the nomenclature. This work was supported by a grant from the Swiss
National Science Foundation (SNF) and the US National Science Foun-
dation (NSF) CHE-0135786.
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Received: December 6, 2004
Published online: January 26, 2005
2294
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