New pyrrolidine and pyrroline derivatives of fullerenes: From the synthesis to the use in light-converting systems

Article abstract of DOI:10.1007/s11172-008-0126-4

The results of the authors' studies on the [2+3] cycloaddition of azomethine and nitrile ylides generated from picolylamine and benzylamine derivatives to fullerenes are systematized and new experimental data are considered. Catalysts and microwave radiation promoting the formation of ylides and their addition to fullerenes were successfully used for the first time. A large series of new pyrrolidine and pyrroline derivatives of fullerenes C ₆₀ and C₇₀ were synthesized and characterized. The proposed procedures afford the reaction products in yields twice as high (80-85%) as those attained by the classical Prato reaction. The reactions proceed with virtually complete regio- (in the case of C₇₀) and stereoselectivity to afford only cis-2',5'-disubstituted and trans-1',2',5'trisubstituted pyrrolidinofullerenes. Pyridyl-substituted pyrrolidinofullerenes react with metalloporphyrins and phthalocyanines to form self-ordered coordination complexes. The latter are analogs of natural photosynthetic antenna systems due to photoinduced charge separation that occurs in these complexes upon exposure to light.

Full text of DOI:10.1007/s11172-008-0126-4

Russian Chemical Bulletin, International Edition, Vol. 57, No. 5, pp. 887—912, May, 2008
887
New pyrrolidine and pyrroline derivatives of fullerenes:
from the synthesis to the use in lightꢀconverting systems
P. A. Troshin,a A. S. Peregudov,b S. I. Troyanov,c and R. N. Lyubovskayaa
aInstitute of Problems of Chemical Physics, Russian Academy of Sciences,
1 prosp. Akad. Semenova, 142432 Chernogolovka, Moscow Region, Russian Federation.
Fax: +7 (496) 522 1852. Eꢀmail: troshin@cat.icp.ac.ru
bA. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
28 ul. Vavilova, 119991 Moscow, Russian Federation.
Fax: +7 (499) 135 6549. Eꢀmail: asp@ineos.ac.ru
cDepartment of Chemistry, M. V. Lomonosov Moscow State University,
1 Leninskie Gory, 119991 Moscow, Russian Federation.
Eꢀmail: stroyano@thermo.chem.msu.ru
The results of the authors’ studies on the [2+3] cycloaddition of azomethine and nitrile
ylides generated from picolylamine and benzylamine derivatives to fullerenes are systematized
and new experimental data are considered. Catalysts and microwave radiation promoting the
formation of ylides and their addition to fullerenes were successfully used for the first time.
A large series of new pyrrolidine and pyrroline derivatives of fullerenes C60 and C70 were
synthesized and characterized. The proposed procedures afford the reaction products in yields
twice as high (80—85%) as those attained by the classical Prato reaction. The reactions proceed
with virtually complete regioꢀ (in the case of C70) and stereoselectivity to afford only cisꢀ2´,5´ꢀ
disubstituted and transꢀ1´,2´,5´ꢀtrisubstituted pyrrolidinofullerenes. Pyridylꢀsubstituted
pyrrolidinofullerenes react with metalloporphyrins and phthalocyanines to form selfꢀordered
coordination complexes. The latter are analogs of natural photosynthetic antenna systems due
to photoinduced charge separation that occurs in these complexes upon exposure to light.
Key words: fullerenes, azomethine ylides, nitrile ylides, 1,3ꢀdipoles, [2+3] cycloaddition,
light conversion, photoinduced charge separation, solar cells.
applied investigations into fullerenes and their derivatives
sharply increased.
Introduction
There are the following two main areas of applied
studies on fullerenes: organic electronics and biomediꢀ
cine. Waterꢀsoluble fullerene derivatives are of interest
for biomedical purposes (see, for example, Refs 3—5).
Some [60]fullerene compounds have found use in photoꢀ
dynamic therapy of malignant tumors,6 other derivatives
proved to be rather efficient bacteriostatic and fungicide
agents,7 and some other derivatives act as antioxidants,
which can find use for the fight against neurodegenerative
processes that cause, in particular, Parkinson’s and
Alzheimer’s diseases.8,9 Fullerene derivatives inhibit variꢀ
ous enzymes, in particular, HIVꢀ1 protease responsible
for the penetration of HIV into cells.10 Hence, fullerene
compounds can be used as the basis for the design of new
AIDS medicines.
The character of the fullerene chemistry becomes more
applied every year. This is associated with the fact that
dozens of unusual reactions were found and various
fullerene derivatives were synthesized during 15 years of
extensive research in this field.1 Data on the reactivities of
fullerenes have been systematized.1,2 These publications
outlined the principal characteristic features that account
for the nature of the majority of chemical transformations
that seem to be exotic as compared to analogous reactions
in the classical organic chemistry. Presently, the fullerene
chemistry is in many respects understandable and preꢀ
dictable, which has somewhat damped interest of researchꢀ
ers in this field. Thus the number of publications on the
fullerene chemistry in 2006 was at least five times smaller
than in 1996,* whereas the number of publications on
For organic electronics, it is essential that fullerene
C60 and many its organic derivatives have good electronꢀ
transport properties. Unmodified fullerene C60 is the best
organic nꢀtype semiconductor, where the electron mobilꢀ
* The results of the literature search using the ISI Web of Sciꢀ
ence in the format “fullerene* OR C60* OR C70*.”
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 873—898, May, 2008.
1066ꢀ5285/08/5705ꢀ0887 © 2008 Springer Science+Business Media, Inc.

888
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
ity is as high as 10 cm2 V–1
s
.
–1 11 Due to these characterisꢀ
volumes of solvents and heating over a long period of time
(10—20 h) and often afford mixtures of products that are
difficult to separate. Extensive expenditure of materials
and energy necessary for the synthesis of organic fullerene
derivatives evidently leads to their high price due to which
these products do not find use in practice. So far, one
organic fullerene derivative, viz., (3ꢀmethoxycarbonylꢀ
propyl)phenylmethano[60]fullerene (PCBM), which is
used for the preparation of organic solar cells, is the most
available. In spite of the fact that the manufacturing techꢀ
nology of this compound has been developed in detail,
the price of this compound is 200 Euro per gram, which is
10 times higher than the price of the starting fullerene.20
In the present study, we systematically investigated
the [2+3] cycloaddition reactions of azomethine ylides
with fullerenes with the aim of developing a simple, conꢀ
venient, and efficient method for the synthesis of organic
fullerene derivatives on a macroscale.
tics, fullerene and its derivatives can be used for the
construction of fieldꢀeffect transistors and integrated
schemes.12,13 In some cases, such transistors were demonꢀ
strated to operate stably in air without additional encapꢀ
sulation.14 In organic lightꢀemitting diodes, fullerene C60
is used as an electronꢀtransport layer or a dopant for holeꢀ
transport layers. The use of fullerenes makes it possible to
reduce the switchꢀon voltage of lightꢀemitting devices, as
well as to enhance the brightness characteristics and the
lifetime.15,16 Organic derivatives of fullerenes are very
important materials for modern organic solar cells having
a light conversion efficiency of 5—6%.17,18
Noncovalently bound systems constructed from fullerene
derivatives and metalloporphyrins can be considered as
models of photosynthetic reaction centers. A series of
such dyads and triads have been studied in recent years.
The efficient photoinduced charge separation is observed
in donor—fullerene systems exposed to light. The lifeꢀ
times of the states reach milliseconds, which is several
orders of magnitude longer than those in other analogous
systems without the involvement of fullerene.19
1. General data on the conventional Prato reaction
The [2+3] cycloaddition of azomethine ylides generꢀ
ated from αꢀamino acids or their derivatives to fullerenes
is referred to as the Prato reaction. In the classical version
of the reaction, amino acids and carbonyl compounds are
used as the reagents. These reactions are accompanied by
decaboxylation and dehydration giving rise to azomethine
ylides; it is these species that add to the double bonds of
the fullerene cage (Scheme 1, reaction A).
The prospects of the practical use of organic fullerene
derivatives calls for the development of manufacturing
technologies. Most of the reactions described in the litꢀ
erature give good results only in syntheses with milligram
amounts of fullerenes, whereas scaling to gram amounts
leads to a sharp decrease in the yield of the products.
Moreover, typical syntheses with fullerenes require large
Scheme 1

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
889
Scheme 2
Hence, this reaction was also referred to as the sarcosine
Prato method (see Scheme 1, reaction C).26
In all versions of the Prato reaction presented in
Scheme 1, the substituents R1—R5 do not stabilize usually
the positive and negative charges in transient azomethine
ylides. Hence, these ylides are very reactive, which results
in a large number of byꢀproducts, and the yields of the
target products are at most 25—40%.26,27 An additional
problem is that the starting amino acids are insoluble in
the reaction medium (only nonpolar organic solvents
where fullerene is soluble are used) due to which the
reaction is heterogeneous.
An enhancement of the efficiency of the Prato reacꢀ
tion necessitates the use of less polar compounds instead
of amino acids insoluble in nonpolar solvents, e.g., amino
acid esters and amides. However, in this case the generaꢀ
tion of azomethine ylides would follow the mechanisms
different, in principle, from that shown in Scheme 1 (reꢀ
action A). NꢀSubstituted amino acid derivatives afford
ylides via iminium hydroxides, which eliminate water on
heating to form azomethine ylides (Scheme 3, reaction
A). NꢀUnsubstituted amino acid esters and amides give
ylides upon thermallyꢀinduced tautomerization of the
intermediate imine (see Scheme 3, reaction B).28 In both
cases, all the steps leading to azomethine ylides are comꢀ
pletely reversible, and the negative charge in the ylides is
stabilized by the electronꢀwithdrawing group —COXR.
Since amino acid esters and imines are readily soluble
in nonpolar organic solvents, their reactions with fullerene
and aldehydes proceed in homogeneous media. Due to
this fact, the products can be obtained in higher yields
(45—80%) as compared to the syntheses involving amino
acids (25—40%). However, in spite of higher yields
of the reactions products, only a few syntheses with
Nꢀsubstituted amino acid esters25—27 and Nꢀunsubstituted
glycine esters and amides29 were documented.
Boc = —C(=O)OBut
The Prato reaction allows, in principle, the simultaꢀ
neous introduction of five substituents into the pyrrolidine
ring fused to fullerene (see Scheme 1). However, such
reactions have not been documented. Several reactions in
which the addition to the fullerene cage affords the
pyrrolidine ring containing three or four substituents
(albeit, in very low yield) have been described.21,22 This is
attributed to the fact that steric hindrance caused by
substituents in ylides prevents approach of the latter to
the fullerene cage.
The fact that these approaches have found little use is
apparently attributed to the possible formation of a mixꢀ
ture of isomers containing substituents in the cis and trans
positions of the pyrrolidine ring. This is why formaldeꢀ
hyde (paraformaldehyde) was used as the carbonyl comꢀ
ponent in the known reactions with Nꢀsubstituted amino
acid esters (generally, with sarcosine esters) (see Scheme 3,
reaction A). Paraformaldehyde is poorly soluble in
organic solvents, so this reaction is also heterogeneous.
We showed that in some cases 1´,2´,5´ꢀtrisubstituted
pyrrolidinofullerenes can be obtained from Nꢀsubstituted
glycine esters with high stereoselectivity to give product 2
as the trans isomer (Scheme 4).
The known syntheses of pyrrolidinofullerenes
from imines derived from glycine, glycylglycine, and
aminomethylphosphonic acid esters29 are presented
in Scheme 5. In all cases, mixtures of stereoisomers
containing mainly the cis adduct were obtained.29 This
stereochemical result of the reaction is attributed to the
2,5ꢀDisubstituted pyrrolidinofullerenes can be syntheꢀ
sized from natural amino acids by the Prato reaction in
moderate yields. With rare exceptions, the reactions
afford mixtures of cis and trans isomers of the adducts (see
Scheme 1, reaction B).23,24 In particular, this is confirmed
by our synthesis of pyrrolidinofullerene 1 containing
phenyl and Bоcꢀprotected (Boc = —C(=O)OBut) aminoꢀ
butyl groups at positions 2´ and 5´ starting from NεꢀBocꢀ
DLꢀlysine (Scheme 2). The reaction afforded a 4 : 1 mixꢀ
ture of the cis and trans isomers. After deprotection, comꢀ
pound 1 can be used for introduction of the fullerene
label into peptides.
The scope of the reaction for the synthesis of 2,5ꢀdiꢀ
substituted pyrrolidinofullerenes is limited also by the fact
that the starting αꢀamino acids (other than natural amino
acids) are not easily accessible. The Prato reaction is perꢀ
formed primarily with Nꢀsubstituted glycine derivatives.25
NꢀMethylglycine (sarcosine) is the most readily accesꢀ
sible reagent and it is most often used in the Prato reaction.

890
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Scheme 3
X = O, NH
from both sides by the bulky phenyl and electronꢀwithꢀ
drawing (Z) groups. This hinders the approach of the
reagent to the fullerene cage. On the contrary, azomethine
ylide having the syn conformation can efficiently react
with double bonds of the fullerene cage to form cis
isomers of 2´,5´ꢀdisubstituted pyrrolidinofullerenes
(Scheme 6, R = H).29
Scheme 4
Scheme 6
fact that the reaction centers in the anti conformation
(resulting in the formation of the trans isomer of the
product) of intermediate azomethine ylide are shielded
R = H, Me, Bn, CH2C6H4OHꢀ4
Scheme 5
The first aim of the present study was to examine the
possibilities of the synthesis of 2´,2´,5´ꢀtrisubstituted
pyrrolidinofullerenes from available natural αꢀamino acid
esters.
2. Synthesis of pyrrolidinofullerenes
starting from derivatives of natural
αꢀamino acids as reactants
Amino acid derivatives of fullerenes possess specific
biological properties and can find use in medicine.30,31
Hence, we made an attempt to synthesize new pyrroliꢀ
dinofullerenes containing fragments of natural αꢀamino
acid methyl esters, viz., Lꢀalanine, Lꢀphenylalanine, and
Lꢀtyrosine methyl esters.32
Z
Yield (%)
trans
cis : trans
cis
COOMe
P(O)(OEt)2
C(O)NHCH2COOEt
40
58
45
21
20
12
2 : 1
3 : 1
4 : 1
The reactions of C60 with imines derived from αꢀamino
acids afford 1,1,3ꢀtrisubstituted azomethine ylides as

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
891
intermediates, whose addition to the fullerene cage is
sterically hindered. Regardless of the conformation of
trisubstituted azomethine ylide, one group (R or COOMe)
hinders the approach of the reactant to the fullerene cage
(see Scheme 6, R ≠ H).
Most of the known imines 3a—r, which were prepared
from Lꢀalanine, Lꢀphenylalanine, and Lꢀtyrosine esters,
do not react with fullerene upon prolonged reflux (10—12
h, 180 °C) in 1,2ꢀdichlorobenzene (1,2ꢀDCB).32 The only
exception are pyridineꢀ2ꢀcarbaldimines 3a—c. Under the
aboveꢀmentioned conditions, the latter compounds react
with fullerene to form the corresponding trisubstituted
pyrrolidinofullerenes 4a—c, the isomers containing the
pyridyl group in the trans position with respect to the ester
group in the pyrrolidine ring (Scheme 7) being the major
products.
hydrogen bonding in the intermediate azomethine ylides
is the most reasonable rationale for higher reactivity of
substrates containing 2ꢀpyridyl groups. The possible staꢀ
bilization of azomethine ylides by hydrogen bonding has
been discussed earlier.28 Apparently, the hydrogen bondꢀ
ing leads to a decrease in the
energy of the transition state in
both the ylide tautomerization
step and the [2+3] cycloaddition
to the fullerene cage.
The reaction of C60 with 2ꢀpy—CH=NCH(R)COOMe
(the reaction time was 15—20 min) was accompanied by a
rather low conversion of the reactants (40—50%), which
was not increased under reflux over a longer period
of time. The yields of the target products (based on the
consumed C60) are in the range of 20—60% and are subꢀ
stantially lower than those in the analogous reactions of
fullerene with 1,3ꢀdisubstituted ylides (see Scheme 5).29
It is of note that all reactions afford cisꢀ2´,5´ꢀbisꢀ
(2ꢀpyridyl)pyrrolidino[3´,4´:1,2][60]fullerene (5) as a
byꢀproduct in rather high yield (15—45%). The isolation
of this compound confirms the existence of equilibrium
between isomeric imines 3 and 6 (Scheme 8). The presꢀ
ence of a catalytic amount of water enables hydrolysis of
the imine yielding a carbonyl compound and an amine.
The coupling of the carbonyl and the amine components
in the system gives rise to new imines 7 and 8 (see
Scheme 8). Compounds 7a—c cannot react with fullerene
due to steric hindrance (tautomerization of imine should
afford 1,1,3,3ꢀtetrasubstituted azomethine ylides), whereas
compound 8 readily reacts with C60 to form pyrrolidinoꢀ
fullerene 5 via intermediate 1,3ꢀdisubstituted ylide. This
reaction pathway can dominate over the desired addition
of imines 3a—c because imine 8 is less sterically hindered
and, consequently, more reactive with respect to fullerene.
R1—CH=N—CH(R2)COOMe
3a—r
3
R1
R2
3
R1
R2
a
b
c
d
e
f
g
h
i
2ꢀpy
2ꢀpy
2ꢀpy
3ꢀpy
4ꢀpy
Me
CH2Ph
4ꢀHOC6H4
Me
j
k
l
m
n
o
p
q
r
4ꢀpy
Ph
4ꢀO2NC6H4
4ꢀMe2NC6H4
3ꢀpy
CH2Ph
CH2Ph
CH2Ph
CH2Ph
Me
Me
Me
Me
CH2C6H4OHꢀ4
CH2C6H4OHꢀ4
CH2C6H4OHꢀ4
Ph
4ꢀpy
Ph
4ꢀO2NC6H4
4ꢀMe2NC6H4
3ꢀpy
4ꢀO2NC6H4 CH2C6H4OHꢀ4
4ꢀMe2NC6H4 CH2C6H4OHꢀ4
CH2Ph
Isomeric imines 3d,e, 3i,j, and 3n,o containing 3ꢀ and
4ꢀpyridyl groups proved to be inactive in the reactions
with fullerene C60. This indicates that the substantially
higher reactivity of 2ꢀpy—CH=NCH(R)COOMe cannot
be accounted for by the electronꢀwithdrawing effect (the
mesomeric or inductive effect) or the basic properties
of the 2ꢀpyridyl group. The intramolecular N—H...N
Scheme 7
1,2ꢀDCB
3, 4
R
Yield (%)
cisꢀ4
transꢀ4
5
a
b
c
Me
CH2Ph
CH2C6H4OHꢀ4
36
27
20
27
0
1
15
35
45

892
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Scheme 8
Thus, we have studied for the first time the [2+3]
cycloaddition reactions of imines derived from αꢀamino
acid esters with fullerene.
The formation of pyrrolidinofullerene 5 provides
evidence that picolylamineꢀbased imines of type 6 react
with fullerenes. The only indication of the possible genꢀ
eration of azomethine ylides from imines based on
2ꢀpicolylamine in reactions with classical dipolarophiles
was found in the literature.35 We have examined in detail
the possibility of using various picolylamine derivatives as
reactants for the functionalization of fullerene C60.
3. Synthesis of pyrrolidinofullerenes from C60
using picolylamines for the generation
of azomethine ylides
3.1. 2ꢀPicolylamine and Nꢀsubstituted
2ꢀpicolylamines as reactants
Use of unsubstituted 2ꢀpicolylamine for the generation
of azomethine ylides. Earlier35 it has been found that imiꢀ
nes prepared from 2ꢀpicolylamine and aldehydes undergo
tautomerization to azomethine ylides, which are readily
involved in [2+3] cycloaddition reactions with various
dipolarophiles. The mechanism of transformation of imiꢀ
nes into azomethine ylides is presented in Scheme 3 (reꢀ
action B). We showed36 that a wide range of imines based
on 2ꢀpicolylamine can be used for the functionalization
of [60]fullerene. This method was used for the synthesis
of pyrrolidinofullerenes 5 and 9—11 in 55—70% yields
(Scheme 9).37 Analogously, pyrrolidinofullerene 14 conꢀ
R = Me (a), CH2Ph (b), CH2C6H4OHꢀ4 (c)
Scheme 9
The reaction of C60 with alanine ester 3a gives an
almost equimolar mixture of cis and trans isomers of
pyrrolidinofullerene 4a, which was chromatographically
separated from byꢀproduct 5, unconsumed fullerene, and
small amounts of polyaddition products. Isomers 4a could
not be separated by chromatography even with the use of
various eluents and stationary phases (silica gel, neutral
and basic alumina). By contrast, the formation of prodꢀ
ucts 4b,c proceeded highly stereoselectively, and almost
pure trans isomers of the reaction products were isolated.
The compositions and structures of pyrrolidinoꢀ
fullerenes 4a—c and 5 were established by elemental analyꢀ
sis, electrospray mass spectrometry, IR and UVꢀvis
spectroscopy, and 1H and 13C NMR spectroscopy.
1,2ꢀDCB, 2—10 min
1
Based on the interpretation of the H NMR spectra,
the conclusions can be drawn about the spatial arrangeꢀ
ment of the substituents in the pyrrolidine ring. The sigꢀ
nals for the methine protons of the pyrrolidine ring conꢀ
taining cis electronꢀwithdrawing groups are observed at
higher field than the signals for the protons of the correꢀ
sponding trans isomers.29,33,34
Comꢀ
pound
R
Yield
(%)
Comꢀ
pound
R
Yield
(%)
5
9
10
2ꢀpy
Ph
3ꢀpy
65
72
55
11
12
13
4ꢀpy
2ꢀpy
Ph
68
4—5
∼3.5

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
893
Scheme 10
N(5)
N(6)
N(7)
1,2ꢀDCB, 2—10 min
Fig. 1. Molecular structure of pyrrolidinofullerene 5.36
The reaction of C60 with 2ꢀpicolylamine and pyridineꢀ
2ꢀcarbaldehyde affords also a small amount (~4—5%) of
transꢀ2´,5´ꢀbis(2ꢀpyridyl)pyrrolidino[3´,4´:1,2][60]fulꢀ
lerene (12). The yield of minor transꢀ2´ꢀpyridylꢀ5´ꢀphenylꢀ
pyrrolidino[3´,4´:1,2][60]fullerene (13) is ~3.5%. Even
trace amounts of the corresponding trans isomer were not
detected in the synthesis of compound 14.
taining the imidazolinophenyl substituent was synthesized
by Goldshleger et al.38 and by our research group (Scheme 10).*
The synthesis is very simple to perform. Solutions of
fullerene C60, 2ꢀpicolylamine, and excess aldehyde in 1,2ꢀ
DCB were refluxed for 2—10 min. These reactions can be
carried out both in air and in an inert atmosphere. In both
cases, the compositions and yields of the products are
identical within experimental error. As a rule, the converꢀ
sion of fullerene under these conditions is 70—90%, and
it is not increased when the reaction mixture is refluxed
over a longer period of time. In some cases, the conversion
of fullerene and the yields of the products can be someꢀ
what increased with the use of the corresponding imine
instead of a mixture of 2ꢀpicolylamine and an aldehyde.
The target reaction products were isolated by column
chromatography on silica gel.
The 1H NMR spectrum of compound 12 substantially
differs from the spectrum of the isomeric pyrrolidinoꢀ
fullerene 5 (Fig. 2). As mentioned above, the signal for the
x
a
#
*
9.0 8.5 8.0 7.5 7.0
6.5 6.0 5.5
δ
The 1H and 13C NMR spectra of pyrrolidinofullerenes
5 and 9—11 show that these compounds are individual
diastereomers containing substituents at positions 2´ and 5´
of the pyrrolidine ring in the cis or trans configuration.
The cis configuration of the pyridyl groups in compound
5 was established based on Xꢀray diffraction data for the
1 : 1 complex of 5 with zinc mesoꢀtetraphenylporphyrinate
(ZnTPP) (Fig. 1).36 The coordination mode of the elecꢀ
tronꢀdonor and ꢀacceptor components in this complex
will be discussed below.
b
*
9.0 8.5 8.0 7.5 7.0
6.5 6.0 5.5
δ
* The spectroscopic data reported38 for compound 14 are subꢀ
stantially different from those obtained in the present study. In
our case, the positions of the signals in the H NMR spectrum
and their assignment were confirmed by the twoꢀdimensional
NOESY spectrum (see the Experimental section).
Fig. 2. 1H NMR spectra of compounds 5 (a) and 12 (b). The
signals for the methine protons of the pyrrolidine ring are
denoted by the symbol *; the signals for the solvents (CHCl3 and
toluene) as admixtures, by the symbols # and x, respectively.
1

894
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
methine protons of the pyrrolidine ring in the trans isoꢀ
mer is observed at a lower field than that of the cis isomer.
Similar differences have been observed earlier34 for the cis
and trans isomers of 2´,5´ꢀbis(2ꢀmethoxycarbonyl)pyrroliꢀ
dinofullerene.
Analogous differences are observed in the spectra of
unsymmetrical 2´,5´ꢀdisubstituted pyrrolidinofullerenes.
Thus the signals for the methine protons of the cis isomer 9
are present at higher field than those of the trans isomer 13.
We additionally confirmed the stereochemistry of unsymꢀ
metrical 2´,5´ꢀdisubstituted pyrrolidinofullerenes using the
nuclear Overhauser effect (NOE), which has been observed
for the methine protons of compound 14.
Thus, the reactions of azomethine ylides generated
from 2ꢀpicolylamineꢀbased imines with [60]fullerene afꢀ
ford almost exclusively cisꢀ2´,5´ꢀdisubstituted pyrrolidinoꢀ
fullerenes. This selectivity is record for [2+3] cycloaddition
reactions with fullerenes.
Similar highly stereoselective [2+3] cycloaddition reꢀ
actions of azomethine ylides to nonfullerene dipolaroꢀ
philes were documented.28 It was hypothesized that ylides
containing the 2ꢀpyridyl or carbonyl group are stabilized
in the syn conformation by intramolecular hydrogen bonding.28
When using fullerene as a dipolarophile, yet another factor
should be taken into account. This is the steric hindrance
to the approach of azomethine ylides to the fullerene
cage. Ylides in the Sꢀshaped anti conformation contain
one bulky substituent on each side; the steric repulsion
between these substituents results in that they are no more
coplanar with the nitrogen atom (Scheme 11).29 The groups
deviating from the plane of ylide (the RHC+—N—CH–py
triangle) prevents the ylide from approaching the fullerene
cage. However, both substituents can be coplanar in synꢀylides,
which can easily attack the fullerene cage in this conforꢀ
mation (see Scheme 11).
This suggestion was confirmed by semiempirical quanꢀ
tum chemical calculations (the AM1 model), which were
performed for two conformations of the azomethine ylide
generated from pyridineꢀ2ꢀcarbaldehyde and 2ꢀpicolylamine.
Actually, the optimized syn conformation is planar and is
32 kJ mol–1 more stable than the structure of antiꢀylide in
which one pyridyl group deviates from the plane of the
ylide (Fig. 3).
Fig. 3. Conformation of azomethine ylide generated from pyriꢀ
dineꢀ2ꢀcarbaldehyde and 2ꢀpicolylamine based on semiempirical
quantum chemical calculations (AM1 model).
The steric control in the step of addition of ylides to
the fullerene cage is indirectly confirmed by the fact that
fullerene C60 either does not react with 2ꢀpicolylamine
and ketones (for example, with heptadecyl methyl keꢀ
tone) upon prolonged heating (18 h) in 1,2ꢀDCB or gives
the expected cycloadducts in very low yields (products
with acetone are formed in 5—10% yields). The converꢀ
sion of fullerene in these reactions is generally rather low
(25—40%), and the reactions afford numerous unidentiꢀ
fied products in yields of at most 1%.
NꢀSubstituted derivatives of 2ꢀpicolylamine as precurꢀ
sors of azomethine ylides. With the aim of extending the
synthetic potential of the aboveꢀdescribed method, the
possibility of generation of azomethine ylides from monoꢀ
Nꢀsubstituted 2ꢀpicolylamines and aldehydes was examꢀ
ined. Examples of such reactions are unknown. However,
these reactions would be expected to proceed via iminium
hydroxides followed by elimination of a water molecule
(Scheme 12) by analogy with the mechanism considered
above for Nꢀsubstituted amino acid esters (see Scheme 3,
reaction A).
Actually, upon refluxing of C60, Nꢀsubstituted 2ꢀpicolylꢀ
amine, and aldehyde in a molar ratio of 1 : 1.1 : 1.3 in 1,2ꢀDCB
for 2—10 min, a high degree of conversion of the reacꢀ
tants (85—95%) is achieved, and the corresponding
pyrrolidinofullerenes are obtained in 55—80% yields
(Scheme 13).
Scheme 12
Scheme 11

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
895
Scheme 13
#
a
1,2ꢀDCB, 2—10 min
#
#
9
8
7
6
5
4
δ
b
Compound
R1
R2
Yield (%)
15
16
17
18
19
20
2ꢀpy
2ꢀpy
Ph
3ꢀpy
3ꢀpy
3ꢀpy
2ꢀpy
4ꢀpy
2ꢀpy
4ꢀpy
3ꢀpy
2ꢀpy
80
55
60
70
65
75
21
3ꢀpy
55
The formation of only one diastereomer of the product in
the reaction under study is evidenced by the NMR spectra of
the monoadducts isolated from the reaction mixture. The hinꢀ
dered rotation of the substituents at the N atom of the
pyrrolidine ring is confirmed by the fact that the 1H NMR
spectra show a pair of doublets corresponding to the methylꢀ
ene group (Fig. 4).39
The chemical shifts of the methine protons in the
1H NMR spectra of pyrrolidinofullerenes 15—21 and the NOE
analysis provide evidence that compounds 15—21 are trans
isomers.
150
130
110
90
70
50
δ
Fig. 4. H (a) and 13C (b) NMR spectra of pyrrolidinofullerene
20. The signals for solvents (benzene and toluene) as admixtures
are denoted by the symbol #.
1
The molecular structure of pyrrolidinofullerene 20 was
established by the Xꢀray diffraction study of the adduct
of this compound with carbon disulfide. The projection of
molecule 20 obtained from the Xꢀray diffraction data
(Fig. 5) unambiguously shows that two 2ꢀpyridyl groups
are in the trans positions with respect to the pyrrolidine
ring. The similarity of the NMR spectra of compounds
15—21 suggests that all trisubstituted pyrrolidinofullerenes
under study are trans isomers.
The exclusive formation of transꢀcycloadducts 15—21
is a distinguishing feature of the reactions of ylides based
on Nꢀsubstituted 2ꢀpicolylamines. On the contrary, the
aboveꢀdescribed reactions of fullerene with ylides preꢀ
pared from unsubstituted 2ꢀpicolylamine and aldehydes
afford cisꢀ2´,5´ꢀdisubstituted pyrrolidinofullerenes 5 and
9—11 as the major products. This opposite diastereoꢀ
selectivity of the [2+3] cycloaddition of 1,1,3ꢀtrisubstiꢀ
tuted and 1,3ꢀdisubstituted azomethine ylides is attributed
Fig. 5. Molecular structure of compound 20 in the crystal solvate
20•0.93CS2.

896
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Fig. 6. Conformations of azomethine ylide generated from pyridineꢀ2ꢀcarbaldehyde and bis(2ꢀpicolyl)amine based on semiempirical
quantum chemical calculations (AM1 model).
to the presence of a bulky substituent bound to the nitroꢀ
gen atom. For example, azomethine ylide prepared from
pyridineꢀ2ꢀcarbaldehyde and bis(2ꢀpicolyl)amine exists
in three conformations, viz., Wꢀ, Uꢀ, and Sꢀshaped conꢀ
formations. The reaction of fullerene with Sꢀylide would
be expected to give the product containing substituents at
positions 2´ and 5´ of the pyrrolidine ring in the trans
configuration, whereas ylides having the W or U conforꢀ
mation give cisꢀadducts. The geometry of all three conꢀ
formations was optimized (Fig. 6) and the heats of their
formation were estimated by semiempirical quantum
chemical calculations (AM1). The Sꢀshaped conformer
was demonstrated to be more stable than the Wꢀ and
Uꢀshaped conformers by 8 and 29 kJ mol–1, respectively,
which is consistent with the experimental results.
with the involvement of the pyridyl nitrogen atom is imꢀ
possible. It should be emphasized that this stabilization
plays an important role in the formation of azomethine
ylides from 2ꢀ and 4ꢀpicolylamine derivatives (Scheme 14).
Scheme 14
The above data show that the use of Nꢀsubstituted
2ꢀpicolylamines for the generation of azomethine ylides
can be considered as an efficient method for the synthesis
of 1´,2´,5´ꢀtrisubstituted pyrrolidinofullerenes.
3.2. Use of 3ꢀpicolylamine and Nꢀsubstituted
3ꢀpicolylamines as reactants
However, we found that the reaction can be initiated
by DBU or AcOH as the catalyst. Pyrrolidinofullerene 22
was obtained in 35% yield within 1—2 h (Scheme 15) in
the presence of ~0.15 equiv. of DBU. The use of a larger
amount of the catalyst leads to a decrease in the yield of
the product due apparently to the side reaction of C60 with
DBU giving rise to an insoluble complex.40 Other bases
(Et3N, Bu3N, and Py) proved to be inefficient. The
exception is DABCO (1,4ꢀdiazabicyclo[2.2.2]octane),
which initiates the reaction but to a much lesser extent
than DBU.
First attempts to use 3ꢀpicolylamine instead of 2ꢀpicolylꢀ
amine in [2+3] cycloaddition reactions to fullerene have
failed. The reaction of equimolar amounts of 3ꢀpicolylꢀ
amine, pyridineꢀ3ꢀcarbaldehyde, and [60]fullerene in 1,2ꢀDCB
under reflux for 8 h did not give even trace amounts of the
reaction product. The inertness of 3ꢀpicolylamineꢀbased
imines is associated with the fact that mesomeric stabiliꢀ
zation of the carbanionic center in the corresponding ylide

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
897
Scheme 15
oven) for 15—25 min with 1,2ꢀDCB and 1,2,4ꢀtrichloroꢀ
benzene as the solvents afforded pyrrolidinofullerene 22
in 70—75% yields.41
8 h
As far as we know, the aboveꢀdescribed reactions are
the first examples of the catalyzed [2+3] cycloaddition to
fullerene. The possibility of generation of azomethine
ylides by tautomerization of 3ꢀpicolylamineꢀbased imiꢀ
nes, as well as the initiation effect of organic bases in
these reactions, have not hitherto been described in orꢀ
ganic chemistry.
DBU, 1—2 h
AcOH, 3—6 h
1,2ꢀDCB,
PrCOOH, 3—6 h
The acidꢀ and baseꢀcatalyzed tautomerization of
3ꢀpicolylamineꢀbased imines to azomethine ylides can be
described by the following mechanism. The DBU molꢀ
ecule deprotonates the methylene group of the imine (genꢀ
erated in situ), and DBU•H+ delivers a proton to the
nitrogen atom to give a 1,3ꢀdipolar ion. The reaction in
the presence of acetic acid should proceed according to
the reverse mechanism. Initially, the imine is protonated
by AcOH and then the AcO– anion abstracts H+ from the
CH2 group of the protonated imine (Scheme 16).
PrCOOH, microwave
radiation, 15—25 min
1
The H and 13C NMR spectra of fullerene 22 show
that this compound is the individual cis isomer.
The stereoselectivity of [2+3] cycloaddition remains
unchanged in the reactions of imines derived from 2ꢀ and
3ꢀpicolylamines. The formation of the intramolecular
NH...NPy hydrogen bond is unlikely for azomethine ylides
containing only 3ꢀpyridyl groups (as in the synthesis of
compound 22). Hence, the high diastereoselectivity in
the reactions with the use of 2ꢀpicolylamineꢀbased imines
is unlikely to be attributed to the intramolecular hydrogen
bonding. Apparently, only the steric discrimination beꢀ
tween the syn and anti conformations of azomethine ylides
in the step of [2+3] cycloaddition to the fullerene cage
determines the stereochemical outcome.
Acetic acid appeared to be a very efficient catalyst in
spite of the fact that it should be used in larger amounts
than DBU (8 equiv.) and the reaction time is longer (3—6 h).
The yield of the target product 22 is twice as high as in the
DBUꢀcatalyzed reaction (see Scheme 15).
The reaction with the use of butyric acid as the cataꢀ
lyst afforded the product in even higher yield (80%). Howꢀ
ever, the reaction time was also ~6 h. The reaction under
microwaveꢀinduced heating (in a domestic microwave
Scheme 16

898
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Scheme 18
The reaction of bis(3ꢀpicolyl)amine and pyridineꢀ3ꢀ
carbaldehyde with C60 in the presence of acid catalysts
(AcOH or PrCOOH) affords transꢀ1´,2´,5´ꢀtrisubstituted
pyrrolidinofullerene 23 in high yield (Scheme 17). As in
the case of unsubstituted 3ꢀpicolylamine, the reaction
proceeds only in the presence of a catalyst.
Scheme 17
Comꢀ
R
Yield (%)
pound
i
ii
iii
RCOOH (8 equiv.), 9 h
24
25
4ꢀpy
3ꢀpy
35
25
30
—
70
—
C60, 1,2ꢀDCB, ∆
Reagents and conditions: i. C60, 1,2ꢀDCB, ∆, 2—10 min.
ii. C60, PhCl, ∆, 0.15 equiv. DBU, 2—10 min. iii. C60, PhCl,
∆, 8 equiv. AcOH, 3—6 h.
products 24 and 25 in relatively low yields with moderate
conversion of fullerene (Scheme 18). An increase in the reacꢀ
tion time to 6 h does not increase the yield of the products.
Pyrrolidinofullerene 24 was not formed upon heating
of the reactants under reflux in chlorobenzene for 3 h.
This fact is attributed to the lower boiling point of the
solvent (~130 °C). However, the reaction is completed in
10—20 min in the presence of DBU (the conversion of
C60 is ~70% and it is not increased upon heating over a
longer period of time). Acetic acid has a less pronounced
effect on the reaction rate (8 equiv. of acetic acid are
necessary for the completion of the reaction in 3—6 h);
however, the use of acetic acid leads to a substantial inꢀ
crease in the yield of the product.
R = Me, Pr
3.3. Use of 4ꢀpicolylamine
and Nꢀsubstituted 4ꢀpicolylamines
as reactants
NꢀSubstituted 4ꢀpicolylamines can also be used as subꢀ
strates for the generation of azomethine ylides. For example,
the uncatalyzed reaction of (3ꢀpicolyl)(4ꢀpicolyl)ꢀamine and
pyridineꢀ4ꢀcarbaldehyde with C60 in 1,2ꢀDCB afforded
an inseparable mixture of transꢀpyrrolidinoꢀfullerene 26
and isomeric pyrrolidinofullerene 27 in a ratio of 4 : 1
The reactivity of imines derived from 4ꢀpicolylamine
in the [2+3] cycloaddition to fullerene C60 appeared to be
lower than that of 2ꢀpicolylamineꢀbased imines, but it is
substantially higher than that of imines derived from
3ꢀpicolylamine. The reaction of equimolar amounts of
4ꢀpicolylamine, an aldehyde, and C60 in 1,2ꢀDCB under
reflux for 10—30 min in the absence of a catalyst leads to
1
(Scheme 19), as evidenced by the H NMR spectrum of
the product.
Scheme 19
C60, 1,2ꢀDCB, ∆

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
899
Scheme 20
The selective formation of compounds 26 and 18—21
in the reactions with unsymmetrical dipicolylamines inꢀ
dicates that the 2ꢀ and 4ꢀpyridyl groups have a stronger
stabilizing effect on the carbanionic center of the resultꢀ
ing azomethine ylide than the 3ꢀpyridyl group. This corꢀ
responds to the mesomeric stabilization of picolyl carꢀ
banions with the involvement of the 2ꢀ and 4ꢀpyridyl
groups but not of the 3ꢀpyridyl fragment (see Scheme 14).
4. Picolylamines as reactants
for functionalization of fullerene C70
The reactivity of fullerene C70 has been much less
studied than that of fullerene C60 because of both the low
availability of C70 and low selectivity of many reactions of
this compound. The carbon cage of [70]fullerene has a
lower symmetry than C60, due to which several isomeric
products can be formed upon scission of one double bond.
For example, the [2+3] cycloaddition of azomethine ylides
to the cage of fullerene C70 affords three isomers A—C;42
the number of the major products decreases to two
(A and B) in the reaction under microwave radiation
(Scheme 20).43
Scheme 20 shows the reaction giving rise to pyrroliꢀ
dinofullerenes unsubstituted at positions 2´ and 5´ of the
pyrrolidine ring, which excludes the formation of stereroꢀ
isomers. The synthesis of 2´,5´ꢀdisubstituted pyrrolidine
derivatives of C70 has not been described in the literature.
However, this reaction would be expected to give nine
isomeric products provided the addition also proceeds at
three most labile double bonds in the fullerene C70 cage.
Some adducts would exist as two enantiomers.
We were the first to examine the possibility of syntheꢀ
sizing diꢀ and trisubstituted pyrrolidine derivatives of
fullerene C70 in reactions with azomethine ylides generꢀ
ated from picolylamine derivatives.44 It was found that
the use of the latter provides high selectivity of the addiꢀ
tion. Thus all reactions afford one major cycloaddition
product. For example, the reactions of imines derived
from 2ꢀ and 3ꢀpicolylamines gave pyrrolidinofullerenes
28 and 29, respectively (Scheme 21), containing ~5—8%
of other isomeric adducts.
Apparently, the reactions of C70 with Nꢀsubstituted
picolylamines and aldehydes are even more regioꢀ and
(C1 symmetry)
(C1 symmetry)
(C1 symmetry)
(Cs symmetry)
(Cs symmetry)
(C1 symmetry)
(C1 symmetry)
(C1 symmetry)
(C1 symmetry)

900
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Scheme 21
a
9
8
7
6
5
4
δ
b
160
140
120
100
80
60
δ
Reagents and conditions: i. C70, 1,2ꢀDCB, 180 °C, 10 min.
ii. C70, 1,2ꢀDCB, 8 equiv. PrCOOH, 180 °C, 8 h.
1
Fig. 7. H (a) and 13C (b) NMR spectra of compound 30.
stereoselective. Scheme 22 shows an example of these
reactions giving rise to pyrrolidinofullerene 30 as the only
product. High purity of pyrrolidinofullerene 30 was conꢀ
firmed by NMR spectra (Fig. 7). Such a high selectivity is
unusual for fullerene C70, and these reactions have not
been documented earlier.
(ROESY and NOESY) as was described above for comꢀ
pound 14. The spectra show cross peaks confirming the
existence of interactions between two methine protons of
the pyrrolidine ring.
At the same time, the absence of these peaks in the
NOESY spectrum of compound 30 confirms the trans
configuration of the substituents in this compound. It should
be noted that structurally similar pyrrolidinofullerene 20
prepared from C60 also exists as the trans isomer (this was
unambiguously established by Xꢀray diffraction).
The cis configuration of the substituents in compounds
28 and 29 was confirmed by 2D NMR spectroscopy
Scheme 22
The bond in the carbon cage of C70 to which the
addend is bound has remained an open question. Accordꢀ
ing to NMR data, all compounds are unsymmetrical (C1
point group), due to which the structures of Csꢀsymmetric
9,10ꢀadducts can be excluded from consideration. When
choosing between the structures of unsymmetrical 8,25ꢀ
and 11,12ꢀadducts, preference should be given to the
former compounds because it is known that the 8,25 bond
is the most reactive site in the C70 cage. This conclusion
was confirmed by data from absorption spectroscopy.45—47
The absorption spectrum of compound 30 is completely
identical to the spectra of 8,25ꢀC70H2 (see Ref. 45) and
other 8,25ꢀdihydro[70]fullerenes46 and differs from the
spectra of other isomers of C70R2.
Thus, the [2+3] cycloaddition of 1,3ꢀdisubstituted
azomethine ylides to C70 affords cis isomers of 2´,5´ꢀdiꢀ
Reagents and conditions: i. C70, 1,2ꢀDCB, 180 °C, 5 min.

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
901
substituted pyrrolidinofullerenes. By contrast, the reacꢀ
tions of 1,2,3ꢀtrisubstituted ylides give trans adducts.
Hence, the stereoselectivity of [2+3] cycloaddition to
fullerene C70 is completely analogous to that of the correꢀ
sponding aboveꢀdescribed reactions of [60]fullerene. The
very high selectivity of this method opens new approach
to the functionalization of [70]fullerene.
The composition of the products was confirmed by
MALDIꢀTOF mass spectrometry. The spectra of comꢀ
pounds 32a and 33a are very similar and contain peaks at
m/z 720 (C60+), 914 ([32a – H]+ and [33a + H]+), and
1002 ([32a – H + C3H8COO]+ and [33a + C3H8COOH]+).
1
The H and 13C NMR spectra of pyrrolidinofullerene
32a showed that this compound is the individual Csꢀsymꢀ
metric diastereomer containing Ph groups in the cis conꢀ
figuration. The high stereoselectivity of [2+3] cycloaddiꢀ
tion corresponds to the aboveꢀdescribed reactions giving
2,5ꢀdisubstituted pyrrolidinofullerenes from picolylamine
imines. The synthesis of pyrrolidinofullerene 32a from
31a is the first example of generation of azomethine ylides
by tautomerization of imines containing no stabilizing
electronꢀwithdrawing groups.
5. Synthesis of pyrrolidinoꢀ and pyrrolinofullerenes
from benzylamineꢀbased imines
Above, we have described the successful catalytic
tautomerization of imines derived from 3ꢀpicolylamine
into azomethine ylides in [2+3] cycloaddition to fullerene
C60. Mesomeric stabilization of these ylides with the inꢀ
volvement of the pyridyl nitrogen atom (see Scheme 14)
is absent, and only the electronꢀdeficient pyridyl group
has an inductive effect. In the further study, we examined
the possibility of generation of ylides from imines conꢀ
taining no electronꢀwithdrawing groups that stabilize the
carbanionic center, as in benzylamineꢀbased imine 31a
(Scheme 23).48
1
The H and 13C NMR spectroscopic data for comꢀ
pound 33a are consistent with the literature data49 for
pyrrolinofullerene 33a, which has been prepared by the
photochemical addition of the corresponding diphenylꢀ
azirine to C60.
The formation of pyrrolinofullerene 33a in the reacꢀ
tion of fullerene C60 with imine 31a in the presence of
butyric acid as the catalyst was unexpected. Apparently,
the reaction is accompanied by dehydrogenation of the
starting imine 31a to the corresponding nitrile ylide, which
reacts with fullerene to form pyrrolinofullerene as the
addition product (Scheme 24). The oxidative dehydrogeꢀ
nation has been observed earlier50 in the reactions of C60
with secondary amines. In spite of the fact that these
reactions were carried out under argon or nitrogen, the
inert gas contained trace amounts of oxygen, which
enabled the oxidative addition of amines to fullerene.
The reaction of imine 31a, C60, and butyric acid
(8 equiv.) in 1,2ꢀDCB under reflux in an argon atmoꢀ
sphere for 10—15 h leads to pyrrolidinofullerene 32a and
pyrrolinofullerene 33a with ~50% conversion of fullerene.
Scheme 23
Scheme 24
R = H (a), NMe2 (b)
Reagents and conditions: i. C60, 1,2ꢀDCB, 180 °C, PrCOOH
(8 equiv.), 10—15 h, argon, hν. ii. C60, 1,2ꢀDCB, 180 °C,
PrCOOH (8 equiv.), 10—15 h, air, hν.

902
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Apparently, the reaction of imine 31a with C60 under
argon was also accompanied by partial oxidation of the
imine to the nitrile ylide by oxygen impurities present in
the system. To verify this hypothesis, we performed the
reaction of imine 31a with C60 in air under reflux in 1,2ꢀDCB.
The reaction mixture was additionally irradiated using a
60 W incandescent lamp to increase the amount of singlet
oxygen, which is formed in the presence of fullerene as
the sensitizer. This reaction afforded pyrrolinofullerene
33a as the only product (see Scheme 23).
The known methods for the synthesis of pyrrolinoꢀ
fullerenes involve the photochemical addition of monoꢀ
or disubstituted azirines,49,51 the catalytic reactions with
certain isocyanates,52 the thermal addition of activated
imidodithioates accompanied by elimination of one thiol
residue,53 the oxidative addition of imines generated from
benzophenone and glycine esters,54 and the reactions of
fullerene with imidoyl halides.55 All these methods have
certain drawbacks because either the starting compounds
are difficult to prepare or the reactions have a limited
synthetic application. Hence, the in situ oxidation of
readily available benzylamineꢀbased imines to nitrile ylides
can be used as a convenient method for the synthesis of
pyrrolinofullerenes. To confirm this suggestion, we carꢀ
ried out the reactions of [60]fullerene with imines 31b
(see Scheme 23) and 31c (Scheme 25).
The oxidative addition of imine 31b to C60 proceeds
smoothly and affords the expected pyrrolinofullerene 33b
as the only product in 35% yield (see Scheme 23). Howꢀ
ever, the analogous reaction of fullerene with imine 31c
gave unexpected results. Thus the conversion of fullerene
was only 35% even after reflux for 20 h. 4ꢀNitrobenzalꢀ
dehyde, pyrrolinofullerene 33a, and a 4 : 1 mixture of
pyrrolinofullerene 33c´ and pyrrolidinofullerene 32c were
isolated from the mixture of the reaction products. It
should be noted that the expected pyrrolinofullerene 33c
was not detected among the reaction products.
1
The H and 13C NMR spectra of a mixture of comꢀ
pounds 33c´ and 32c measured at 400 and 100 MHz,
respectively, are similar to those published in the literaꢀ
ture55 for openꢀcage pyrrolinofullerene 33c″. However,
the 13C NMR spectrum (150 MHz) showed signals for all
three sp3ꢀhybridized C atoms expected for structure 33c´
(δ 84—89) and a set of four signals for the sp3ꢀhybridized
C atoms of compound 32c (δ 74—78). The presence of 60
intense signals (in addition to weak resonances belonging
to 32c) in the field characteristic of sp2ꢀhybridized C atoms
confirmed the C1 symmetry group of pyrrolinofullerene 33c´.
Scheme 25
Reagents and conditions: C60, 1,2ꢀDCB, 180 °C, PrCOOH (8 equiv.), 10—15 h, air.
Note. The yields of the products are based on consumed fullerene.

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
903
Therefore, in spite of the similarity of the initial specꢀ
troscopic data and the data published in the literature for
openꢀcage pyrrolinofullerene 33c″, the structure of the
newly synthesized compound corresponds to pyrrolinoꢀ
fullerene 33c´. Apparently, pyrrolinofullerene 33c´ has
been synthesized in the earlier study55 as well; however,
structure 33c″ has been erroneously assigned to the reacꢀ
tion product because of the low quality of the 13C NMR
spectrum. Earlier,48 we have also misinterpreted the specꢀ
troscopic data for a mixture of compounds 33c´ and 32c.
We assigned the structure of pyrrolinofullerene 33c″´ conꢀ
taining two nitrophenyl group to the reaction product
because some signals in the 1H NMR spectrum were acciꢀ
dentally identical. More recently, an independent deꢀ
tailed study56 of the reaction of fullerene with Nꢀbenzylꢀ
4ꢀnitrobenzimidoyl chloride showed that the reaction
afforded only two compounds 33c and 33c´, whereas
openꢀcage pyrrolinofullerene 33c″ was not produced at
all. The results of the study56 prompted us to analyze the
spectra of a mixture of compounds 33c´ and 32c in more
detail, which allowed us to reliably establish the structures
of the reaction products.
cenes, porphyrins, phthalocyanines, tetrathiafulvalenes,
etc.) were described in the literature.57 Among these comꢀ
pounds, selfꢀorganizing supramolecular ensembles based
on fullerene and porphyrin derivatives are of most interest
because their properties are similar to those of natural
photosynthetic antennae. Several fullerene derivatives
containing pyridyl or imidazole groups, which readily form
complexes with zinc and ruthenium porphyrinates, were
characterized. The solution properties of coordinatively
bonded systems formed by fullerene derivatives containꢀ
ing chelating groups and various metalꢀcontaining elecꢀ
tronꢀdonating molecules were studied in detail (see, for
example, Refs 19, 58, and 59). The association constants
of the components were determined. The photoinduced
electronꢀtransfer efficiencies and the lifetimes of the
chargeꢀseparated states were estimated. It is noteworthy
that in some cases the lifetimes of the chargeꢀseparated states
are hundreds of microseconds or even several milliseconds.
In earlier studies,19,60,61 it has been demonstrated that
the reactions of ZnTPP with ligands 34—38 are virtually
equally efficient. However, the reaction with 2´ꢀ(2ꢀpyridyl)ꢀ
pyrrolidinofullerene 39 does not proceed due to strong
steric shielding of the pyridyl nitrogen atom. The comꢀ
plex formation through coordination of metalloporphyrins
at the pyrrolidine nitrogen atom in compounds 40 and 41
was not observed.60 This is attributed to the electronꢀ
withdrawing effect of the fullerene cage resulting in a
substantial shift of the electron density from the pyrrolidine
nitrogen atom toward the π system of the fullerene cage.
This substantially decreases the basicity and the complexꢀ
ation ability of the pyrrolidine nitrogen atom in the aboveꢀ
mentioned fullerene derivatives compared to unsubstituted
pyrrolidine.61
The above data show that the acidꢀcatalyzed reactions
of C60 with benzylamineꢀbased imines can be used with
advantage for the synthesis of disubstituted pyrrolinoꢀ
fullerenes. Moreover, these reactions can potentially be
applied to other dipolarophiles, which provides new
approaches to the synthesis of various molecules containꢀ
ing pyrrolidine or pyrroline rings.
6. Coordinatively bonded systems
based on pyridylꢀsubstituted pyrrolidinoꢀ
fullerenes, metalloporphyrins,
We convincingly demonstrated that pyrrolidinofullerene
5 forms complexes with metalloporphyrins with the inꢀ
volvement of the pyrrolidine nitrogen atom.36 The strucꢀ
ture of the complex with ZnTPP was established by Xꢀray
diffraction (Fig. 8). The zinc atom of metalloporphyrin
forms a coordination bond with the pyrrolidine nitrogen
and metallated phthalocyanines
6.1. Complexes with metalloporphyrins
Numerous and various covalently bound and coordiꢀ
nation dyads of fullerenes with various donors (metalloꢀ

904
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
N(3) N(2)
N(2)
N(1)
N(3)
Zn
N(1)
N(4)
N(4)
Zn
N(5)
N(5)
N(6)
N(7)
N(6)
N(7)
Fig. 8. Projections of the molecule of complex 5•ZnTPP.36
Scheme 26
atom of compound 5. The average Zn—N(porphyrin) disꢀ
tance is 2.09(1) Å, whereas the Zn—N(pyrrolidine ring)
coordination bond is substantially longer (2.29(1) Å). Due
to the axial coordination, the zinc atom deviates from the
plane passing through four nitrogen atoms of the porphyꢀ
rin ring by 0.34 Å.
More recently, the reaction of pyrrolidinofullerene 5
with ZnTPP was studied in solution (cyclohexane), and
the complexation constant was estimated by absorption
and fluorescence spectroscopy.62 The formation of the 1 : 1
complex of compound 14 with ZnTPP was established,
and the photophysical properties of this complex in soluꢀ
tion were studied (Scheme 26).63
The investigation of the photophysical properties of
the coordination complexes of pyrrolidinofullerenes 5 and
14 with ZnTPP in solution confirmed the photoinduced
charge separation in these systems. The absorption of a
light quantum gives rise to excitons of the electronꢀdonor
porphyrin or the electronꢀacceptor pyrrolidinofullerene
followed by the electron transfer and the formation of the
ionꢀradical pair [A•–]•[D•+] (see Scheme 26). The simiꢀ
lar photoinduced charge separation is observed in the
photosynthesis in natural systems, viz., chloroplasts, and,
consequently, coordination complexes of pyrrolidinoꢀ
fullerenes with ZnTPP are similar to natural photosynꢀ
thetic antennae.58
6.2. Complexes with zinc phthalocyanine
We examined the complexation of pyrrolidinofulꢀ
lerenes with zinc phthalocyanine (ZnPc) in solution and

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
905
thin films.64—66 In particular,
we compared the characterisꢀ
tics of pyrrolidinofullerene 23
I
a
1.0
containing three chelating
pyridyl groups with those of
methanofullerene PCBM,
which contains no chelating
groups and which cannot
form complexes with zinc
phthalocyanine.
0.8
0.6
0.4
0.2
Unsubstituted zinc phthalocyanine is insoluble in
dichloromethane but is notably soluble in concentrated
solutions of compound 23 in CH2Cl2, as evidenced by the
absorption spectra presented in Fig. 9. The absorption
band Q of ZnPc in the 23—CH2Cl2 system is completely
identical in the shape and position to the maximum in the
spectrum of a solution of ZnPc in pyridine where ZnPc—
pyridine complexes are known to be formed.
It was also shown that pyrrolidinofullerene 23 more
efficiently induces luminescence quenching of ZnPc in
toluene compared to PCBM. The luminescence quenchꢀ
ing is associated with the fast electron transfer from the
excited ZnPc molecule to a fullerene compound giving
rise to a chargeꢀseparated ionꢀradical pair. In the Stern—
Volmer plot, the luminescence quenching of ZnPc upon
the addition of PCBM is described by a straight line with
650
700
750
λ/nm
I
b
0.8
0.6
0.4
0.2
the Stern—Volmer constant (KSV) of 38•103 dm3 mol–1
,
which corresponds to the diffusion mechanism of interacꢀ
tions between donor and acceptor molecules (Fig. 10).
Pyrrolidinofullerene 23 is characterized by a positive deꢀ
viation from the straight line. This suggests the presence
of supramolecular interactions between 23 and ZnPc. This
650
700
750
λ/nm
I0/I
c
A
A (rel. units)
1´
4
0.10
0.05
2
1
1
3
2
1
2´
500 600
λ/nm
2
0
10
20
30
C•10–6/mol L–1
3
Fig. 10. Luminescence quenching of ZnPc upon the addition of
PCBM (a) or compound 23 (b) (the increase in the concentraꢀ
tion of PCBM and 23 is indicated by the arrow) and a compariꢀ
son of the luminescence quenching efficiency for ZnPc upon
the addition of PCBM (1) and compound 23 (2) (experimental
data are represented by points and the results of calculations are
indicated by the straight line, KSV = 38•103 dm3 mol–1) in the
Stern—Volmer plot (c) (see Ref. 65); C is the fullerene concenꢀ
tration.
600
650
700
750 λ/nm
Fig. 9. Absorption spectra of ZnPc in pyridine (/20) (1) and
saturated solutions of ZnPc in the 23—CH2Cl2 system (absorpꢀ
tion of 23 was subtracted) (2) and the PCBM—CH2Cl2 system
(absorption of PCBM was subtracted) (3). The spectra of soluꢀ
tions of ZnPc in 23—CH2Cl2 (1´) and PCBM—CH2Cl2 (2´)
without subtraction of absorption of the fullerene compound64
are shown in the inset.

906
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Scheme 27
at 690—694 nm, which resembles the absorption specꢀ
trum of phthalocyanine in pyridine or the 23—CH2Cl2
system (see Fig. 9). Upon deposition of PCBM onto the
surface of a ZnPc film, the spectral pattern remains virtuꢀ
ally unchanged (see Fig. 11). This suggests the absence of
coordination interactions between the components.
fact also confirms that compound 23 forms a complex
with ZnPc in solution (Scheme 27). As can be seen from
Scheme 27, this pyrrolidinofullerene can form two differꢀ
ent 1 : 1 complexes and one 1 : 2 complex.65
The formation of complexes of compound 23 with
ZnPc in thin films was demonstrated by absorption specꢀ
troscopy.66
The absorption spectrum of films of the starting ZnPc
shows a broad band with two maxima at 630 and 712 nm
(Fig. 11), whereas the spectrum of this compound in pyriꢀ
dine has one dominant narrow intense absorption band
at 674 nm (Q band, see Fig. 9). The deposition of
pyrrolidinofullerene 23 on the surface of a ZnPc film
results in a substantial change in the spectral pattern.
Thus the spectrum shows a narrow band with a maximum
7. Use of pyridylꢀsubstituted pyrrolidinoꢀ
fullerenes as electronꢀwithdrawing
materials for solar cells
The highly efficient photoinduced charge separation
in complexes of pyrrolidinofullerenes with zinc phthaloꢀ
cyanine is an important prerequisite for their use as mateꢀ
rials for organic solar cells. We demonstrated64—66 that

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
907
A (rel. units)
by vacuum deposition (this results in a higher cost price of
such cells).67
0.6
Photovoltaic cells are characterized by the following
parameters: the shortꢀcircuit current (Isc), the openꢀcirꢀ
cuit voltage (Uoc), the fill factor (FF), and the conversion
efficiency (η). These parameters for PCBM/ZnPcꢀbased
cells (see Fig. 12, curve 1) and 23/ZnPcꢀbased cells (see
Fig. 12, curve 2) are given below.
0.4
4
0.2
Isc/mA cm–2 Uoc/mV
FF
η (%)
3
Cell
PCBM/ZnPc
23/ZnPc
2.2
4.9
450
620
0.54
0.48
0.5
1.5
0
2
1
400
500
600
700
800 λ/nm
Pyrrolidinofullerenes containing pyridyl groups proved
to be also of prime importance for the preparation of
multicomponent solar cells, viz., a new type of photovolꢀ
taic cells in which two electronꢀdonor and two electronꢀ
acceptor materials are combined.66 The structure of such
cells is schematically presented in Fig. 13. The photoactive
part of the photovoltaic cell consists of the following two
layers: zinc phthalocyanine (the lower layer) and a blend
of fullerene compounds and a polyconjugated polymer
(the upper layer). The advantage of these cells is that they
can convert light throughout the visible region (350—850
nm). This is confirmed by the spectral dependences of the
quantum yield of light conversion (see Fig. 13). It can be
seen that the photocurrent in cells in which only PCBM
is used as the electronꢀacceptor material is generated priꢀ
marily in the shortꢀwavelength region of the spectrum
(350—550 nm). The addition of a small amount of
pyrrolidinofullerene 23 (4%) to PCBM increases sharply
the efficiency of photocurrent generation in the longꢀ
wavelength region of the spectrum (550—850 nm). This
effect is associated with the formation of coordinatively
bonded ZnPc—23 complexes at the interface between the
layers.
Fig. 11. Absorption spectra of films of PCBM and pyrrolidinoꢀ
fullerene 23 (1), pure ZnPc (2), and ZnPc with deposited layers
of compound 23 (3) and PCBM (4).
pyrrolidinofullerenes can be used with advantage as elecꢀ
tronꢀacceptor components in bilayer photovoltaic cells
whose schematic construction is presented in Fig. 12.
Substrates having an indium—tin oxideꢀbased (ITOꢀ
based) conducting layer and a deposited layer of the
PEDOT:PSS hole conductor are used as one of the elecꢀ
trodes. A zinc phthalocyanine layer is sputtered in vacuo
onto the electrode, and then a fullerene compound
(PCBM or 23) is deposited from solution. In the final
step, an aluminum cathode is deposited by thermal evapoꢀ
ration in vacuo.
The efficiency of light conversion by solar cells based
on the 23—ZnPc combination is several times higher than
that by cells based on the PCBM—ZnPc system (see Fig.
12). The efficiency of light conversion (1.5%) by bilayer
23—ZnPc cells (compound 23 is deposited from soluꢀ
tion) is close to the record values for cells based on unꢀ
modified C60 and ZnPc, which were completely prepared
i/mA cm–2
a
b
1
2
25
20
15
10
5
6
5
4
3
2
0
–5
1
–0.2
0
0.2
0.4 0.6 0.8
1.0 U/V
Fig. 12. a. Architecture of a bilayer photovoltaic cell: 1, a substrate; 2, an indium—tin oxideꢀbased (ITOꢀbased) conducting layer; 3, a
deposited layer of the hole conductor PEDOT:PSS; 4, a ZnPc layer; 5, the fullerene compound (PCBM or 23); 6, an aluminum
cathode. b. Voltammetric curves for the gadgets based on PCBM/ZnPc (1) and 23/ZnPc (2).

908
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
Q (%)
25
a
b
2
6
20
15
10
5
5
1
4
3
2
0
1
400
500
600
700
λ/nm
Fig. 13. a. Structure of a multicomponent photovoltaic cell: 1, a substrate; 2, an indium—tin oxideꢀbased (ITOꢀbased) conducting
layer; 3, a deposited layer of the hole conductor PEDOT:PSS; 4, a ZnPc layer; 5, a blend of the fullerene compounds (PCBM + 23)
and a polyconjugated polymer; 6, an aluminum cathode. b. Spectroscopic dependences of the quantum yield of light conversion (Q)
for multicomponent cells based on PCBM (1) and the PCBM—23 mixture (2).66
(CH2); 71.86; 76.03; 76.30; 77.99; 78.43; 128.06; 128.14; 128.27;
128.32; 128.55; 134.62; 134.83; 135.63; 135.83; 136.44; 136.92;
137.37; 139.42; 139.56; 139.84; 140.03; 141.41; 141.54; 141.75;
141.84; 141.88; 141.90; 141.95; 142.05; 142.08; 142.19; 142.38;
142.46; 142.52; 142.56; 142.88; 143.05; 144.15; 144.20; 144.44;
144.48; 145.01; 145.11; 145.15; 145.22; 145.27; 145.29; 145.36;
145.54; 145.72; 145.74; 145.89; 145.92; 146.00; 146.03; 146.06;
146.09; 146.18; 146.57; 146.62; 146.96; 146.99; 153.32; 153.38;
153.63; 153.69; 154.82.
transꢀ2´ꢀBenzyloxycarbonylꢀ1´ꢀ[4ꢀ(tertꢀbutoxycarbonylꢀ
amino)butyl]ꢀ5´ꢀphenylpyrrolidino[3´,4´:1,9](C60ꢀIh)ꢀ
[5,6]fullerene (2). Fullerene C60 (200 mg, 0.28 mmol) was disꢀ
solved in chlorobenzene (100 mL) under argon. Benzaldehyde
(40 mg, 0.38 mmol) and Nꢀ[2ꢀ(NꢀBocꢀamino)ethyl]glycine benꢀ
zyl ester (431 mg, 1.4 mmol) were added to the solution. The
reaction mixture was refluxed for 6 h, the solvent was removed
on a rotary evaporator, and a solution of the residue in a 1 : 1
toluene—hexane mixture was chromatographed on silica gel
(40—100 µ). The target product was eluted with toluene. The
yield was 170 mg (55%), an amorphous paleꢀbrown powder,
m.p. >250 °C (with decomp.). 1H NMR (400 MHz, CDCl3), δ:
1.57 (s, 9 H, Me3C); 3.16, 3.35, 3.60, and 3.78 (all m, 1 H each,
CH2); 5.02 (s, 1 H, NHCO); 5.40 and 5.51 (both d, 1 H each,
CH2Ph); 6.01 (s, 1 H, CHCOOBn); 6.57 (s, 1 H, CHPh); 7.37
The quantum yields of light conversion in multicomꢀ
ponent cells are low (~2.2%); however, further optimizaꢀ
tion would be expected to considerably improve this
parameter.
8. Experimental
We report the improved procedures for the synthesis of
pyrrolidine and pyrroline derivatives of fullerenes that have not
been described in detail in the cited publications. The spectroꢀ
scopic data for compounds 1, 2, 13, 19—21, 32a,c, 33a,b, and
33c´ are presented for the first time. For compounds 14—18, the
refined spectroscopic data are reported; these data are someꢀ
what different from those published earlier.37
The NMR spectra were recorded on Bruker AMXꢀ400 (400
MHz), Bruker Reflex III, and Bruker Avance 600 (600 MHz)
spectrometers in CDCl3 (1H), a 10 : 1 CS2—cyclohexaneꢀd12
mixture (13C), and a 10 : 1 CS2—acetoneꢀd6 mixture with the
use of signals of the residual protons of the solvent or Me4Si as
the internal standard.
cisꢀ5´ꢀ[4ꢀ(tertꢀButoxycarbonylamino)butyl]ꢀ2´ꢀphenylꢀ
pyrrolidino[3´,4´:1,9](C60ꢀIh)[5,6]fullerene (1). Fullerene C60
(200 mg, 0.28 mmol) was dissolved in chlorobenzene (100 mL)
under argon. Then benzaldehyde (40 mg, 0.38 mmol) and a
mixture of isomers of Bocꢀprotected lysine (350 mg, 1.4 mmol),
which was prepared according to a standard procedure,68 were
added. The reaction mixture was heated at 120 °C for 6 h,
cooled to ambient temperature, and filtered. The filtrate was
concentrated on a rotary evaporator. The residue was dissolved
in toluene and chromatographed on a 15×1 cm column (silica
gel 40—100 µ). The target product was eluted with 0.6% methaꢀ
nol in toluene. The yield was 70 mg (25%), an amorphous paleꢀ
brown powder, m.p. >250 °C (with decomp.). 1H NMR (400 MHz,
CDCl3), δ: 1.52 (s, 9 H, Me3C); 1.86 (m, 4 H, 2 CH2); 2.39 and
2.79 (both m, 1 H each, CH2—CH—N); 2.89 (dd, 1 H, CHN,
J = 10.5 Hz, J = 2.5 Hz); 3.32 (t, 2 H, CH2NHCO, J = 5.3 Hz);
4.71 (br.s, 1 H, NHCO); 5.88 (s, 1 H, NCHPh); 7.41 (t, 1 H,
CHAr, J = 7.1 Hz); 7.48 (t, 2 H, CHAr, J = 7.5 Hz); 7.86 (d, 2 H,
CHAr, J = 7.1 Hz). 13C NMR (100 MHz, CS2—acetoneꢀd6), δ:
23.23 (CH2); 25.87 (CH2); 28.34 ((CH3)3C); 33.28 (CH2); 40.33
(m, 3 H, CHAr); 7.49 (m, 5 H, CHAr); 7.83 (d, 2 H, CHAr
,
J = 6.6 Hz). 13C NMR (100 MHz, CS2—acetoneꢀd6), δ: 28.32
((CH3)3C); 39.00 (CH2); 47.94 (CH2); 66.74 (CH2Ph); 70.63;
72.75; 75.19; 77.35 ((CH3)3CO); 78.30; 127.35; 128.43; 128.58;
128.88; 129.37; 129.46; 135.14; 135.89; 136.13; 136.25; 136.88;
137.51; 139.28; 139.46; 139.88; 139.91; 141.42; 141.49; 141.53;
141.62; 141.73; 141.82; 141.89; 141.92; 141.96; 141.99; 142.36;
142.42; 142.53; 142.78; 142.97; 144.16; 144.27; 144.43; 144.49;
144.91; 144.98; 145.07; 145.10; 145.27; 145.37; 145.45; 145.66;
145.76; 145.90; 145.93; 146.01; 146.06; 146.14; 146.20; 146.32;
146.51; 147.11; 147.23; 150.45; 153.22; 153.62; 154.79; 155.47;
169.87; 154.82; 169.16 (C=O).
Synthesis of pyridylꢀsubstituted pyrrolidinofullerenes from
2ꢀ and 4ꢀpicolylamine derivatives (general procedure). Fullerene
C60 (200 mg, 0.28 mmol) was dissolved with stirring in 1,2ꢀDCB
(20 mL) in air for 2 h. A solution of picolylamine or Nꢀsubstituted
picolylamine (1.2 equiv.) in 1,2ꢀDCB (5 mL) was added to the

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
909
solution of fullerene. Then the corresponding aldehyde (5—10 equiv.)
was added to the reaction mixture. In some cases, a solution of
imine (1.2 equiv.), which was prepared by the reaction of
equimolar amounts of picolylamine and aldehyde in CH2Cl2 in
the presence of anhydrous sodium sulfate,29 was added to
fullerene. The reaction mixture was heated in air or under argon
for 2—10 min (if a 2ꢀpicolylamine derivative was used as the
reactant) or 10—30 min (if the reactant contained no 2ꢀpicolyl
groups). The progress of the reaction was monitored by TLC.
After completion of the reaction, the reaction mixture was cooled
to room temperature, diluted with toluene (100 mL; in the case
of compound 17, the reaction mixture was additionally diluted
with hexane (450 mL)), and chromatographed on a silica gel
column (40—60 µ). Unconsumed fullerene was eluted with toluꢀ
ene (or with a 1 : 2 toluene—hexane mixture in the case of 17);
subsequent elution was carried out with a toluene—methanol
mixture (a toluene—hexane mixture for compound 17). After
chromatography, the solutions of pyrrolidinofullerenes were
concentrated on a rotary evaporator to 3—5 mL, and hexane
(20—30 mL) was added. The precipitates that formed were sepaꢀ
rated by centrifugation, washed three times with hexane, and
dried in air. The spectroscopic data for compounds 9—12, 17,
and 24—27 have been published earlier;37 for compounds 28—30,
see Ref. 44.
139.94; 141.38; 141.44; 141.59; 141.72; 141.85; 141.97; 142.15;
142.26; 142.39; 142.49; 142.83; 142.98; 144.19; 144.30; 144.38;
144.49; 144.86; 144.89; 144.92; 144.96; 145.08; 145.10; 145.18;
145.32; 145.37; 145.42; 145.52; 145.68; 145.70; 145.89; 145.98;
146.01; 146.10; 146.58; 146.61; 147.04; 147.13; 149.09; 149.40;
149.80; 150.07; 152.40; 153.27; 153.57; 156.83; 158.45; 159.90.
Compound 18. 1H NMR (400 MHz, CDCl3), δ: 3.75 and
4.33 (both d, 1 H each, CH2, J = 14.3 Hz); 5.96 (s, 1 H); 7.21 (d,
1 H, CHpy, J = 7.8 Hz); 7.38 (dt, 1 H, CHpy, J = 5.6 Hz, J = 1.8 Hz);
7.40 (s, 1 H); 7.45 (dd, 1 H, CHpy, J = 7.2 Hz, J = 4.1 Hz); 7.73
(t, 1 H, CHpy, J = 8.4 Hz, J = 1.6 Hz); 7.95 (br.s, 1 H, CHpy);
7.97 (d, 2 H, CHpy, J = 7.8 Hz); 8.66 (d, 1 H, CHpy, J = 3.4 Hz);
8.69 (s, 1 H, CHpy); 8.72 (d, 2 H, CHpy, J = 5.0 Hz); 9.06 (d,
1 H, CHpy, J = 4.7 Hz). 13C NMR (100 MHz, CS2—C6D12), δ:
48.44 (CH2); 72.93; 74.57; 74.71; 75.63; 122.51; 123.11; 123.65;
125.13; 125.35; 125.51; 128.00; 128.71; 130.78; 132.51; 132.77;
134.80; 135.17; 135.89; 136.18; 137.26; 137.81; 139.22; 139.28;
139.73; 139.88; 141.25; 141.29; 141.33; 141.50; 141.57; 141.62;
141.68; 141.72; 141.82; 142.01; 142.15; 142.29; 142.38; 142.70;
142.88; 144.05; 144.15; 144.25; 144.35; 144.76; 144.81; 144.88;
144.96; 145.00; 145.23; 145.29; 145.41; 145.60; 145.64; 145.79;
145.86; 145.97; 146.05; 146.12; 146.18; 146.33; 146.47; 147.11;
147.21; 148.89; 149.11; 149.86; 150.01; 150.26; 152.11; 153.13;
153.29; 156.62; 159.91.
Compound 13. 1H NMR (400 MHz, CS2—acetoneꢀd6), δ:
4.34 (br.s, 1 H, NH); 6.44 and 6.97 (both s, 1 H each, CH—
NH); 7.36 (m, 2 H, CHpy, CHPh); 7.46 (t, 2 H, CHPh, J = 8.3
Compound 19. 1H NMR (600 MHz, CS2—acetoneꢀd6), δ:
3.70 and 4.30 (both d, 1 H each, CH2, J = 14.0 Hz); 5.95 (s, 1 H,
CH—N); 7.17 (t, 1 H, CH, J = 7.8 Hz); 7.25 (d, 1 H, CHpy
J = 7.8 Hz); 7.38 (m, 2 H, CHpy); 7.45 (s, 1 H, CH—N); 7.81
(dt, 1 H, CHpy, J = 7.8 Hz, J = 1.8 Hz); 7.99 (d, 1 H, CHpy
,
Hz); 7.56 (d, 1 H, CHpy, J = 7.6 Hz); 7.82 (dt, 1 H, CHpy
,
J = 7.6 Hz, J = 1.6 Hz); 7.95 (d, 2 H, CHPh, J = 7.6 Hz); 8.85
(d, 1 H, CHpy, J = 4.4 Hz).
,
J = 7.3 Hz); 8.31 (br.s, 1 H, CHpy); 8.48 (s, 1 H, CHpy); 8.56
(m, 2 H, CHpy); 9.09 (d, 1 H, CHpy, J = 4.6 Hz); 9.12 (br.s, 1 H,
CHpy). 13C NMR (150 MHz, CS2—acetoneꢀd6), δ: 48.77 (CH2);
73.29; 74.73; 74.87; 75.64; 123.07; 123.65; 125.87; 128.43;
129.15; 133.40; 135.43; 136.74; 137.73; 138.34; 139.63; 140.21;
141.67; 141.70; 141.77; 141.88; 142.03; 142.06; 142.09; 142.16;
142.23; 142.47; 142.53; 142.64; 142.65; 142.69; 142.76; 143.10;
143.25; 144.48; 144.58; 144.68; 144.74; 145.13; 145.20; 145.23;
145.24; 145.38; 145.45; 145.47; 145.61; 145.65; 145.74; 145.90;
145.96; 145.98; 146.02; 146.04; 146.16; 146.19; 146.25; 146.33;
146.39; 146.68; 147.35; 147.43; 149.10; 149.96; 150.00; 150.18;
150.20; 151.16; 152.57; 153.67; 153.89; 157.19; 160.05; 169.16.
Compound 20. 1H NMR (600 MHz, CDCl3), δ: 3.80 and
4.39 (both d, 1 H each, CH2, J = 14.2 Hz); 6.80 (br.s, 2 H,
CH—N); 7.31 (dt, 2 H, CHpy, J = 5.1 Hz, J = 3.2 Hz); 7.45 (dd,
1 H, CH, J = 4.6 Hz, J = 3.2 Hz); 7.72 (br.s, 2 H, CHpy); 7.77
(t, 2 H, CHpy, J = 7.3 Hz); 8.00 (d, 1 H, CHpy, J = 7.3 Hz); 8.66
(d, 1 H, CHpy, J = 4.6 Hz); 8.75 (s, 1 H, CHpy); 8.88 (br.s, 2 H,
CHpy). 13C NMR (150 MHz, CS2—acetoneꢀd6), δ: 48.85 (CH2);
74.28; 76.42; 122.94; 123.57; 124.73; 133.73; 135.53; 136.39;
136.58; 137.41; 139.50; 139.95; 141.56; 141.83; 141.92; 142.09;
142.17; 142.29; 142.55; 142.65; 143.13; 144.58; 144.63; 145.14;
145.16; 145.25; 145.54; 145.67; 145.96; 146.00; 146.05; 146.22;
146.26; 146.56; 147.33; 148.98; 149.91; 150.03; 153.65; 156.01;
159.31.
Compound 14. 1H NMR (400 MHz, CS2—acetoneꢀd6), δ:
4.13 (t, 1 H, NH, J = 7.3 Hz); 6.13 and 6.21 (both d, 1 H each,
CH—NH, J = 7.3 Hz); 7.17 (d, 1 H, CH of imidazole, J = 16.3
Hz); 7.30 (d, 1 H, CH of imidazole, J = 12.8 Hz); 7.33 (dt, 1 H,
CHpy, J = 7.6 Hz, J = 2.5 Hz); 7.54 (d, 2 H, CHAr, J = 8.5 Hz);
7.86 (dt, 1 H, CHpy, J = 7.6 Hz, J = 1.6 Hz); 7.87 (s, 1 H, CH of
imidazole); 8.10 (d, 1 H, CHpy, J = 6.6 Hz); 8.12 (d, 2 H, CHAr
,
J = 8.4 Hz); 8.72 (d, 1 H, CHpy, J = 4.3 Hz) (assignment was
1
confirmed by H—1H NOESY).
Compound 15. 1H NMR (400 MHz, CDCl3), δ: 4.00 and
4.46 (both d, 1 H each, CH2, J = 15.4 Hz); 6.91 (br.s, 2 H,
CH—N); 7.20 (t, 1 H, CHpy, J = 7.5 Hz); 7.28 (t, 2 H, CHpy
,
J = 7.5 Hz); 7.72 (br.s, 4 H, CHpy); 7.90 (t, 1 H, CHpy, J = 7.5 Hz);
8.10 (d, 1 H, CHpy, J = 7.8 Hz); 8.62 (d, 1 H, CHpy, J = 3.7 Hz);
8.85 (d, 2 H, CHpy, J = 4.1 Hz). 13C NMR (100 MHz,
CS2—C6D12), δ: 52.56 (CH2); 74.10; 76.23; 121.80; 122.06;
122.40; 124.65; 125.30; 128.16; 128.86; 130.98; 135.79; 135.99; 136.46;
137.29; 139.26; 139.76; 141.31; 141.60; 141.68; 141.86; 141.94;
142.07; 142.32; 142.42; 142.90; 144.36; 144.40; 144.92; 145.00;
145.30; 145.44; 145.73; 145.77; 145.86; 145.98; 146.03; 146.41;
146.83; 147.08; 149.34; 153.60; 155.89; 158.96; 159.32. ESI MS
(MeOH + HCOOH), m/z (Irel (%)): 1027 [M•H3O]+ (100).
Compound 16. 1H NMR (400 MHz, CDCl3), δ: 3.96 and
4.40 (both d, 1 H each, CH2, J = 15.2 Hz); 6.12 (s, 1 H,
CH—N); 7.31 (m, 2 H, CHpy); 7.43 (s, 1 H, CH—N); 7.70 (t,
1 H, CHpy, J = 7.5 Hz); 7.92 (m, 4 H, CHpy); 8.07 (d, 1 H,
CHpy, J = 7.8 Hz); 8.61 (d, 1 H, CHpy, J = 4.1 Hz); 8.67 (m,
2 H, CHpy); 9.01 (d, 1 H, CHpy, J = 4.1 Hz). 13C NMR
(100 MHz, CS2—C6D12), δ: 52.44 (CH2); 73.31; 74.82; 75.71;
76.20; 121.85; 121.91; 122.48; 123.89; 125.97; 128.11; 130.92;
135.40; 136.00; 136.08; 137.62; 138.17; 139.27; 139.38; 139.83;
Compound 21. 1H NMR (600 MHz, CS2—acetoneꢀd6), δ:
3.62 and 4.30 (both d, 1 H each, CH2, J = 14.0 Hz); 5.86 (s, 1 H,
CH—N); 7.02 (d, 2 H, CHAr, J = 7.2 Hz); 7.09 (d, 1 H, CH of
imidazole, J = 7.2 Hz); 7.13 (d, 1 H, CH of imidazole, J = 6.5
Hz); 7.22 (s, 1 H, CH—N); 7.33 (m, 2 H, CHpy); 7.42 (d, 2 H,
CHAr, J = 7.4 Hz); 7.62 (s, 1 H, CH of imidazole); 7.71 (t, 1 H,
CHpy, J = 7.5 Hz); 7.92 (d, 1 H, CHpy, J = 7.8 Hz); 8.06 (br.s,

910
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
2 H, CHpy); 8.43 (s, 1 H, CH3ꢀpy); 8.52 (d, 1 H, CHpy, J = 4.4 Hz).
13C NMR (150 MHz, CS2—acetoneꢀd6), δ: 54.79 (CH2); 79.24;
80.97; 81.69; 82.39; 123.13; 127.17; 128.90; 131.79; 134.42;
135.13; 137.22; 139.43; 140.63; 141.14; 141.61; 142.34; 142.58;
143.08; 143.64; 143.76; 144.31; 145.72; 146.18; 146.31; 147.73;
147.76; 147.94; 148.08; 148.12; 148.18; 148.23; 148.46; 148.60;
148.72; 148.74; 148.84; 149.16; 149.34; 149.45; 150.50; 150.59;
150.71; 150.76; 151.17; 151.27; 151.31; 151.40; 151.45; 151.65;
151.68; 151.71; 151.96; 152.02; 152.08; 152.22; 152.29; 152.38;
152.44; 152.83; 153.00; 153.03; 153.12; 153.39; 153.46; 155.06;
155.31; 156.07; 156.18; 156.68; 158.49; 159.78; 160.12; 163.16;
166.29.
Synthesis of pyrrolidinofullerene 20. Fullerene (10.0 g) was
placed into a 2 L flask and dissolved in 1,2ꢀDCB (1.2 L).
2ꢀPicolyl(3ꢀpicolyl)amine (3.3 g, 1.2 equiv.) and pyridineꢀ
3ꢀcarbaldehyde (10 mL) were added. The reaction mixture was
slowly heated with magnetic stirring (30 min) to boiling, reꢀ
fluxed for 5 min, and cooled. Toluene (1.5 L) was added, the
reaction mixture was filtered, and the filtrate was chromatoꢀ
graphed on a 40×5 cm silica gel column (40—60 µ). The product
was eluted with 1.5—2.0% methanol in toluene. The yield was
10.5 g (75%).
Acidꢀcatalyzed synthesis of pyrrolidinofullerenes 22, 23, and
29 (general procedure). In the synthesis of compounds 22 and
29, a solution of the imine (88 mg, 0.45 mmol) prepared from
3ꢀpicolylamine and pyridineꢀ3ꢀcarbaldehyde was added to a soꢀ
lution of fullerene (200 mg of C60 or 235 mg of C70, 0.28 mmol)
in 1,2ꢀDCB (50 mL). In the synthesis of compound 23, a soluꢀ
tion of bis(3ꢀpicolyl)amine (90 mg, 0.45 mmol) in 1,2ꢀDCB
(5 mL) and pyridineꢀ3ꢀcarbaldehyde (0.3 mL) were successively
added. Then acetic or butyric acid (0.2—2.0 mL) was added to
the reaction solution. The reaction mixture was refluxed under
argon for 5—6 h and cooled to ~20 °C. The solvent was removed
on a rotary evaporator. The residue was washed three times with
methanol, dried in air, dissolved in toluene, and chromatoꢀ
graphed on a column. The product was isolated as described
above for the syntheses with 2ꢀ and 4ꢀpicolylamine derivatives.
For the spectroscopic data for compounds 22 and 23, see Ref. 37;
for compound 29, see Ref. 44.
Synthesis of pyrrolidinofullerene 22 using microwave heating.
A solution of butyric acid (2 mL) and the imine (88 mg,
0.45 mmol) prepared from 3ꢀpicolylamine and pyridineꢀ
3ꢀcarbaldehyde in 1,2ꢀDCB or 1,2,4ꢀtrichlorobenzene (2 mL)
was added to a solution of fullerene C60 (200 mg, 0.28 mmol) in
1,2ꢀDCB or 1,2,4ꢀtrichlorobenzene (20 mL). The reaction mixꢀ
ture was placed into a 100ꢀmL Teflon container and heated in a
domestic microwave oven at 600 W until boiling. The boiling of
the solutions in 1,2ꢀDCB and 1,2,4ꢀtrichlorobenzene was obꢀ
served after 6—7 and ~10 min, respectively. Then the mixture
was cooled and again brought to boiling. The progress of the
reaction was monitored by TLC. The reactions were terminated
when the conversion of fullerene reached 80—90%. In the synꢀ
theses in 1,2ꢀDCB, the heating—cooling cycle was repeated
3—4 times. In the syntheses in 1,2,4ꢀtrichlorobenzene, two
heatings were sufficient. Product 22 was isolated according to
the aboveꢀdescribed procedures.
reaction was terminated after 10 h (the conversion of fullerene
reached ~70%). The reaction mixture was cooled and the solꢀ
vent was distilled off on a rotary evaporator. The residue was
washed three times with methanol, dried in air, dissolved in
CCl4 (200—300 mL), and chromatographed on a column.
Pyrrolidinofullerene 32a was eluted with a CCl4—toluene mixture
((2 : 1)→(1 : 1)); pyrrolinofullerene 33a, with a CCl4—toluene
mixture ((1 : 8)→toluene). 1H NMR of compound 32a (400 MHz,
CDCl3), δ: 3.23 (br.s, 1 H, NH); 6.03 (s, 2 H, CH—N); 7.38 (t,
2 H, CHAr, J = 7.5 Hz); 7.47 (t, 4 H, CHAr, J = 7.8 Hz); 8.04 (d,
4 H, CHAr, J = 7.2 Hz). 13C NMR (100 MHz, CS2—acetoneꢀd6),
δ: 75.10 (CH—N, DEPT); 76.32 (C(sp3) of the cage); 128.64;
128.68; 128.86; 136.07; 137.06; 138.14; 139.44; 140.02; 141.54;
141.99; 142.04; 142.09; 142.22; 142.31; 142.60; 142.67; 144.38;
144.68; 145.16; 145.24; 145.27; 145.57; 145.87; 146.12; 146.26;
146.29; 146.94; 147.24; 153.46; 153.72.
Synthesis of pyrrolinofullerene 33a in air. A mixture of imine
31a (50.7 mg, 0.26 mmol), C60 (105 mg, 0.15 mmol), and buꢀ
tyric acid (1.2 mL) in 1,2ꢀDCB (50 mL) was refluxed (a reflux
condenser equipped with a calcium chloride tube) in air for 10 h
under irradiation with a 60 W incandescent lamp. The product
was isolated according to a procedure described above. The
synthesis without irradiation gave pyrrolinofullerene 33a in lower
yield. 1H NMR (400 MHz, CDCl3), δ: 7.23 (s, 1 H, CH—N);
7.39 (t, 1 H, CHAr, J = 7.5 Hz); 7.51 (t, 2 H, CHAr, J = 7.8 Hz);
7.57 (m, 3 H, CHAr); 7.78 (d, 2 H, CHAr, J = 6.9 Hz); 8.26
(two d, 2 H, CHAr, J1 = J2 = 3.7 Hz). 13C NMR (150 MHz,
CS2—acetoneꢀd6), δ: 78.04 (CH—N + C(sp3) of the cage); 88.40
(C=N); 128.39; 128.48; 128.76; 129.11; 129.58; 130.71; 134.02;
134.69; 134.97; 136.39; 136.42; 139.88; 139.92; 140.20; 140.27;
140.64; 141.73; 141.83; 141.91; 141.98; 142.10; 142.14; 142.24;
142.28; 142.36; 142.39; 142.62; 142.73; 142.79; 142.80; 142.85;
143.25; 143.28; 144.11; 144.14; 144.44; 144.52; 145.00; 145.09;
145.12; 145.17; 145.28; 145.41; 145.44; 145.60; 145.70; 145.77;
145.79; 145.86; 145.97; 146.05; 146.40; 146.46; 146.69; 147.01;
147.03; 147.34; 147.88; 148.98; 152.86; 155.41; 170.12.
Synthesis of pyrrolinofullerene 33b. A mixture of imine 31b
(95.2 mg, 0.40 mmol), C60 (210 mg, 0.30 mmol), and butyric
acid (4 mL) in 1,2ꢀDCB (50 mL) was refluxed in air for 12 h
without additional light irradiation (the use of radiation had no
substantial effect on the yield of the product). The product was
isolated according to a procedure described above for pyrroꢀ
linofullerene 33a (elution with toluene). 1H NMR (600 MHz,
CS2—acetoneꢀd6), δ: 3.11 (s, 6 H, NMe2); 6.76 (d, 2 H, CHAr
,
J = 8.7 Hz); 7.10 (s, 1 H, CH—N); 7.34 (t, 1 H, CHPh, J = 6.9 Hz);
7.45 (t, 2 H, CHPh, J = 7.3 Hz); 7.70 (d, 2 H, CHPh, J = 6.9 Hz);
8.32 (d, 2 H, CHAr, J = 8.7 Hz). 13C NMR (150 MHz, CS2—
acetoneꢀd6), δ: 40.07; 78.50; 84.43; 87.97; 111.74; 122.13; 125.46;
125.55; 127.86; 128.26; 128.43; 128.98; 129.23; 129.58; 130.65;
131.53; 133.94; 134.98; 136.26; 139.56; 139.90; 139.93; 140.66;
140.79; 141.64; 141.74; 141.94; 142.06; 142.34; 142.37; 142.39;
142.62; 142.72; 142.78; 142.82; 143.18; 143.26; 144.12; 144.16;
144.48; 144.56; 144.76; 144.89; 145.07; 145.26; 145.35; 145.36;
145.37; 145.49; 145.78; 145.87; 145.92; 146.02; 146.35; 146.38;
147.14; 147.71; 148.83; 149.87; 151.55; 153.37; 155.94; 168.51.
Reaction of C60 with imine 31c. The reagent ratio and the
method of synthesis are those used in the synthesis of compound
33a in air (see above). The reaction mixture was concentrated
on a rotary evaporator. The residue was washed with methanol,
dried in air, and dissolved in CCl4 (400 mL). The resulting
solution was diluted with hexane (200 mL) and filtered. The
Reactions of fullerene with benzylamineꢀbased imines. Synꢀ
thesis of compounds 32a and 33a in an inert atmosphere. Imine
31a (50.7 mg, 0.26 mmol), C60 (105 mg, 0.15 mmol), and buꢀ
tyric acid (1.2 mL) were refluxed in 1,2ꢀDCB (50 mL) under
argon. The progress of the reaction was monitored by TLC. The

New pyrrolidinoꢀ and pyrrolinofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
911
filtrate was passed through a chromatographic column. Succesꢀ
sive elution with CCl4 and a 9 : 1 CCl4—toluene mixture afforded
a mixture of compounds 33a and 4ꢀnitrobenzaldehyde. Subseꢀ
quent elution with 2 : 1 CCl4—toluene and 1 : 1 CCl4—toluene
mixtures gave a mixture of products 32c and 33c´ (one rather
distinct fraction). 1H NMR of compound 32c (600 MHz, CS2—
acetoneꢀd6), δ: 6.16 (s, 1 H); 7.22 (s, 1 H, CH—N); 7.40 (t, 1 H,
CHPh, J = 8.2 Hz); 7.49 (t, 2 H, CHPh, J = 7.6 Hz); 7.70 (d,
6. P. Mroz, G. P. Tegos, H. Gali, T. Wharton, T. Sarna, M. R.
Hamblin, Photochem. Photobiol. S., 2007, 6, 1139.
7. S. Bosi, T. Da Ros, S. Castellano, E. Bafni, M. Prato, Bioorg.
Med. Chem. Lett., 2000, 10, 1043.
8. J. E. Kim, M. Lee, Biochem. Biophys. Res. Commun., 2003,
303, 576.
9. L. L. Dugan, E. G. Lovett, K. L. Queick, J. Lotharius, T. T.
Lin, K. L. O´Malley, Parkinsonism and Related Disorders,
2001, 7, 243.
10. S. H. Friedman, D. L. DeCamp, R. P. Sijbesma, G. Srdanov,
F. Wudl, G. L. Kenyon, J. Am. Chem. Soc., 1993, 115, 6506.
11. T. B. Singh, N. S. Sariciftci, Ann. Rev. Mater. Res., 2006, 36,
199.
2 H, CHPh, J = 7.6 Hz); 8.38 and 8.51 (both d, 2 H each, CHAr
,
J = 8.8 Hz). 13C NMR of compound 32c (150 MHz, CS2—
acetoneꢀd6), δ: 74.17; 75.61; 77.41; 77.97; signals for the C(sp2)
atoms were not identified among the signals of compound 33c´.
1H NMR of compound 33c´ (600 MHz, CS2—acetoneꢀd6), δ:
7.30 (s, 1 H, CH—N); 7.56 (m, 3 H, CHPh); 7.96 (d, 2 H, CHAr
,
12. B. T. Singh, N. Marjanovic, G. Matt, S. Guenes, N. S.
Sariciftci, A. Montaigne, A. Andreev, H. Sitter, R. Schoediauer,
S. Bauer, Org. Electron., 2005, 6, 105.
13. C. Waldauf, P. Schilinsky, M. Perisutti, J. Hauch, C. J.
Brabec, Adv. Mater., 2003, 15, 2084.
14. T. Antopoulos, F. B. Kooistra, H. J. Wondergem,
D. Kronholm, J. C. Hummelen, D. M. de Leeuw, Adv.
Mater., 2006, 18, 1679.
15. J. W. Lee, J. H. Kwong, Apll. Phys. Lett., 2005, 86, 063514.
16. X. D. Feng, C. J. Huang, V. Lui, R. S. Khangura, Z. H. Lu,
Apll. Phys. Lett., 2005, 86, 143511.
17. M. A. Green, K. Emery, D. L. King, Y. Hishikawa,
W. Warta, Prog. Photovoltaics: Res. Appl., 2006, 14, 455.
18. J. Y. Kim, K. Lee, N. E. Coates, D. Moses, T.ꢀQ. Nguyen,
M. Dante, A. J. Heeger, Science, 2007, 317, 222.
19. M. E. ElꢀKhouly, O. Ito, P. M. Smith, F. D´Souza,
J. Photochem. Photobiol. C, 2004, 5, 79.
20. www.solennebv.com, www.adsdyes.com/fullerenes.html,
http://www.sesres.com/FullerenesPrices.asp.
21. F. Conti, C. Corvaja, M. Maggini, G. Scorrano, P. Ceroni,
F. Paolucci, S. Roffia, Phys. Chem. Chem. Phys., 2001, 3,
3518.
J = 8.8 Hz); 8.26 (d, 2 H, CHPh, J = 9.7 Hz); 8.33 (d, 2 H,
CHAr, J = 8.8 Hz). 13C NMR of compound 33c´ (150 MHz,
CS2—acetoneꢀd6), δ: 84.87; 87.41; 88.62; 124.14; 128.87; 129.07;
129.55; 130.50; 131.02; 134.20; 134.31; 135.19; 136.10; 136.35;
140.06; 140.12; 140.29; 140.75; 141.80; 141.83; 141.85; 142.04;
142.08; 142.13; 142.19; 142.30; 142.32; 142.35; 142.49; 142.81;
142.88; 142.90; 143.18; 143.31; 143.34; 144.12; 144.18; 144.35;
144.48; 145.20; 145.30; 145.38; 145.47; 145.50; 145.60; 145.66;
145.71; 145.94; 146.05; 146.13; 146.15; 146.45; 146.48; 147.03;
147.07; 147.09; 147.12; 147.34; 147.86; 148.35; 151.46; 154.64;
171.69.
Xꢀray diffraction study of the adduct of pyrrolidinofullerene
20 with carbon disulfide. The Xꢀray diffraction data were colꢀ
lected from
a needleꢀlike single crystal of dimensions
0.5×0.04×0.04 mm at 100 K on an IPDS (Stoe) area detector
diffractometer using MoꢀKα radiation. The structure of
C78H16N4•0.93CS2 was solved with the use of the SHELXD
program package and refined with anisotropic displacement paꢀ
rameters for N and S atoms and isotropic displacement paramꢀ
eters for all C atoms based on 9116 reflections; 384 parameters
were refined. The carbon disulfide solvent molecules are in parꢀ
tially occupied sites. Due to very low intensities of reflections,
the R factors were rather high (R1 = 0.182, wR2 = 0.349). The
accuracy of determination of C—C and C—N interatomic disꢀ
tances was 0.01 Å; however, the conformation of the molecule
was established quite reliably.
22. G. Schick, M. Levitus, L. Kvetko, B. A. Johnson,
I. Lamparth, R. Lunkwitz, B. Ma, S. I. Khan, M. A. Garsiaꢀ
Garibay, Y. Rubin, J. Am. Chem. Soc., 1999, 121, 3246.
23. X. Tan, D. Schuster, S. Wilson, Tetrahedron Lett., 1998, 39,
4187.
24. M. E. ElꢀKhouly, S. Gadde, G. R. Deviprasad, M. Fudjutsuka,
O. Ito, F. D´Souza, J. Porphyrins Phthalocyanines, 2003, 7, 1.
25. M. Prato, M. Maggini, Acc. Chem. Res., 1998, 31, 519.
26. M. A. Yurovskaya, I. V. Trushkov, Izv. Akad. Nauk, Ser.
Khim., 2002, 343 [Russ. Chem. Bull., Int. Ed., 2002, 51, 367].
27. M. Prato, M. Maggini, C. Giacometti, G. Scorrano,
G. Sandona, G. Farnia, Tetrahedron, 1996, 52, 5221.
28. O. Tsuge, S. Kanemasa, in Adv. Heterocycl. Chem., Ed. A. R.
Katritzky, Academic Press, San Diego—New York—Berkeꢀ
ley—Boston—London—Sydney—Tokyo—Toronto, 1989, 45.
29. S. H. Wu, W. Q. Sun, D. W. Zhang, L. H. Shu, H. M. Wu,
J. F. Xu, X. F. Lao, J. Chem. Soc., Perkin Trans. 1, 1998, 1733.
30. A. Bianco, T. Da Ros, M. Prato, C. Toniollo, J. Peptide Sci.,
2001, 7, 208.
31. D. Pantarotto, N. Tagmatarchis, A. Bianco, M. Prato, Mini
Rev. Med. Chem., 2004, 4, 805.
32. P. A. Troshin, R. N. Lyubovskaya, Fuller. Nanotub. Carb.
Nanostruct., 2005, 13, 345.
33. S. Zhang, L. Gan, C. Huang, M. Lu, J. Pan, X. He, J. Org.
Chem., 2002, 67, 883.
We thank O. A. Troshina, A. B. Kornev, and E. A. Khakina,
who have participated in certain steps of the present study.
This study was financially supported by the Russian
Foundation for Basic Research (Project No. 07ꢀ03ꢀ01078ꢀa)
and the Federal Agency for Science and Innovations
of the Russian Federation (Contracts 02.513.11.3358,
02.513.11.3209, and 02.513.11.3206).
References
1. A. Hirsch, M. Brettreich, Fullerenes Chemistry and Reacꢀ
tions, Wiley—VCH, London, 2004.
2. A. Hirsch, Top. Curr. Chem., 1999, 199, 1.
3. S. Bosi, T. Da Ross, G. Spalluto, M. Prato, Eur. J. Med.
Chem., 2003, 38, 913.
4. T. Da Ros, M. Prato, Chem. Commun., 1999, 663.
5. N. Tagmatarchis, H. Shinohara, Mini Rev. Med. Chem., 2001,
1, 339.

912
Russ.Chem.Bull., Int.Ed., Vol. 57, No. 5, May, 2008
Troshin et al.
34. L. Gan, D. Zhou, C. Luo, H. Tan, C. Huang, M. Lu, J. Pan,
Y. Wu, J. Org. Chem., 1996, 61, 1954.
53. G. Naxakis, P. Sofou, Y. Elemes, Fuller. Nanotub. Carbon
Nanostruct., 2004, 12, 781.
35. R. Grigg, H. Q. N. Gunaratne, V. Sridharan, S. Thianpatanagul,
M. X. Tute, Tetrahedron Lett., 1983, 24, 4363.
36. P. A. Troshin, S. I. Troyanov, G. N. Boiko, R. N. Lyubovskaya,
A. N. Lapshin, N. F. Goldshleger, Fuller. Nanotub. Carb.
Nanostruct., 2004, 12, 435.
37. P. A. Troshin, A. S. Peregudov, D. Muhlbacher, R. N.
Lyubovskaya, Eur. J. Org. Chem., 2005, 14, 3064.
38. N. F. Gol´dshleger, A. N. Lapshin, E. I. Yudanova, N. M.
Alpatova, E. V. Ovsyannikova, Elektrokhimiya, 2006, 42, 19
[Russ. J. Electrochem., 2006, 42, 16 (Engl. Transl.)].
39. A. Ikeda, C. Fukuhara, M. Kawaguchi, M. Numata,
S. Shinkai, S.ꢀG. Liu, L. Echegoyen, J. Chem. Soc., Perkin
Trans. 2, 2000, 307.
40. A. Skiebe, A. Hirsch, H. Ktos, B. Gotsehy, Chem. Phys.
Lett., 1994, 220, 138.
41. A. B. Kornev, P. A. Troshin, A. S. Peregudov, R. N.
Lyubovskaya, 7th Biennial Int. Workshop “Fullerenes and
Atomic Clusters” (St. Petersburg, June 27—July 1, 2005), Book
of Abstracts, St. Petersburg, 2005, 120.
54. G. E. Ball, G. A. Burley, L. Chaker, B. C. Hawkins, J. R.
Williams, P. A. Keller, S. G. Pyne, J. Org. Chem., 2005, 70,
8572.
55. A. A. Ovcharenko, V. A. Chertkov, A. V. Karchava, M. A.
Yurovskaya, Tetrahedron Lett., 1997, 38, 6933.
56. G.ꢀW. Wang, H.ꢀT. Yang, Tetrahedron Lett., 2007, 48, 4635.
57. N. Martín, L. Sanchez, B. Illescas, I. Perez, Chem. Rev.,
1998, 98, 2527.
58. D. M. Guldi, Chem. Soc. Rev., 2002, 31, 22.
59. M. Meijer, G. P. van Klink, G. van Koten, Coord. Chem.
Rev., 2002, 230, 141.
60. F. D´Souza, G. R. Deviprasad, M. E. Zandler, V. T. Hoang,
A. Klykov, M. VanStipdonk, A. Perera, M. E. ElꢀKhouly,
M. Fujitsuka, O. Ito, J. Phys. Chem. A, 2002, 106, 3243.
61. A. Bagno, S. Claeson, M. Maggini, M. L. Martini, M. Prato,
G. Scorrano, Chem. Eur. J., 2002, 8, 1015.
62. A. N. Lapshin, V. A. Smirnov, R. N. Lyubovskaya, N. F.
Gol´dshleger, Izv. Akad. Nauk, Ser. Khim., 2005, 2265 [Russ.
Chem. Bull., Int. Ed., 2005, 54, 2338].
42. S. R. Wilson, Q. Lu, J. Org. Chem., 1995, 60, 6496.
43. F. Langa, P. de la Cruz, A. de la Hoz, E. Espildora, F. P.
Cossio, B. Lecea, J. Org. Chem., 2000, 65, 2499.
44. P. A. Troshin, A. S. Peregudov, S. M. Peregudova, R. N.
Lyubovskaya, Eur. J. Org. Chem., 2007, 5861.
45. C. C. Henderson, C. M. Rohfing, K. T. Gillen, P. Cahil,
Science, 1994, 264, 397.
46. Z. Wang, M. S. Meier, J. Org. Chem., 2003, 68, 3043.
47. O. A. Troshina, P. A. Troshin, A. S. Peregudov, V. I.
Kozlovskiy, R. N. Lyubovskaya, Eur. J. Org. Chem., 2006,
5243.
63. I. A. Mochalov, A. N. Lapshin, V. A. Nadtochenko, V. A.
Smirnov, N. F. Gol´dshleger, Izv. Akad. Nauk, Ser. Khim.,
2006, 1541 [Russ. Chem. Bull., Int. Ed., 2006, 55, 1598].
64. R. Koeppe, P. A. Troshin, R. N. Lyubovskaya, N. S.
Sariciftci, Appl. Phys. Lett., 2005, 87, 244102.
65. R. Koeppe, P. A. Troshin, A. Fuchsbauer, R. N. Lyubovskaya,
N. S. Sariciftci, Fuller. Nanotub. Carb. Nanostruct., 2006,
14, 441.
66. P. A. Troshin, R. Koeppe, A. S. Peregudov, S. M. Peregudova,
M. Egginger, R. N. Lyubovskaya, N. S. Sariciftci, Chem.
Mater., 2007, 19, 5363.
48. P. A. Troshin, A. B. Kornev, A. S. Peregudov, S. M.
Peregudova, R. N. Lyubovskaya, Mendeleev Commun., 2007,
17, 116.
67. J. Drechsel, B. Mannig, F. Kozlovski, D. Gebeyehu,
A. Werner, M. Koch, K. Leo, M. Pfeiffer, Thin Solid Films,
2004, 451, 515.
49. J. Averburg, E. Albrecht, J. Lauterwein, H. Luftman,
J. Mattey, H. Mohn, W. H. Muller, H.ꢀU. ter Meer, Chem.
Ber., 1994, 127, 787.
68. A. A. Gershkovich, V. K. Kibirev, Khimicheskii sintez peptidov
[Chemical Peptide Synthesis], Naukova dumka, Kiev, 1992,
137 (in Russian).
50. K. D. Kampe, N. Egger, M. Vogel, Angew. Chem., Int. Ed.,
1993, 32, 1174.
51. J. Avenburg, J. Mattey, Tetrahedron, 1996, 52, 5407.
52. Y. Tsunenishi, H. Ishida, K. Itoh, M. Ohno, Synlett, 2000,
1318.
Received January 22, 2008;
in revised form April 14, 2008