Synthesis of oxazolidinofullerenes/thiazolidinofullerenes: Novel reaction of [60]fullerene with isocyanates/isothiocyanates promoted by ferric perchlorate

Article abstract of DOI:10.1039/c4ra10199e

The facile one-step reaction of [60]fullerene with isocyanates/isothiocyanates in the presence of ferric perchlorate generates a series of oxazolidinofullerenes/thiazolidinofullerenes, which are difficult to prepare by common methods. The direct dissolution approach plays an important role in the efficient synthesis of oxazolidinofullerenes/thiazolidinofullerenes. A possible reaction mechanism for the product formation is proposed. This journal is

Full text of DOI:10.1039/c4ra10199e

View Article Online
View Journal
RSC Advances
This article can be cited before page numbers have been issued, to do this please use: F. Li, L. Liu, Y. Zhu,
X. Zhang, L. Chen, X. Liang, J. Shi and J. Wu, RSC Adv., 2014, DOI: 10.1039/C4RA10199E.
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Accepted Manuscripts are published online shortly after
acceptance, before technical editing, formatting and proof reading.
Using this free service, authors can make their results available
to the community, in citable form, before we publish the edited
article. This Accepted Manuscript will be replaced by the edited,
formatted and paginated article as soon as this is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes
to the text and/or graphics, which may alter content. The journal’s
standard Terms & Conditions and the Ethical guidelines still
apply. In no event shall the Royal Society of Chemistry be held
responsible for any errors or omissions in this Accepted Manuscript
or any consequences arising from the use of any information it
contains.
www.rsc.org/advances

Page 1 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
Graphical content:
Synthesis of oxazolidinofullerenes/thiazolidinofullerenes: Novel reaction
[60]fullerene with isocyanates/isothiocyanates promoted by ferric
perchlorate
Fa-Bao Li, Ye-Fei Zhu, Xiao-Feng Zhang, Ji-Long Shi, Jun Wu, Liu Chen, Xiao-Xue
Liang and Li Liu
The facile one-step reaction of [60]fullerene with isocyanates/isothiocyanates in the
presence
of
ferric
perchlorate
generates
a
series
of
oxazolidinofullerenes/thiazolidinofullerenes, which will be difficult to prepare by
common methods. The direct dissolution approach plays an important role in the efficient
synthesis of oxazolidinofullerenes/thiazolidinofullerenes. A possible reaction mechanism
for the product formation is proposed.
R1
R1
N
O
N
C O
O
7 examples
up to 39% yield
xH2O
Fe(ClO4)3
R2
R2
N
S
N
C S
O
8 examples
up to 66% yield

RSC Advances
Page 2 of 45
View Article Online
DOI: 10.1039/C4RA10199E
Synthesis of oxazolidinofullerenes/thiazolidinofullerenes: Novel
reaction [60]fullerene with isocyanates/isothiocyanates promoted by
ferric perchlorate†
Fa-Bao Li,*a Ye-Fei Zhu,a Xiao-Feng Zhang,a Ji-Long Shi,a Jun Wu,a Liu Chena
Xiao-Xue Lianga and Li Liu*a
aHubei Collaborative Innovation Center for Advanced Organic Chemical Materials,
Ministry of Education Key Laboratory for the Synthesis and Application of Organic
Functional Molecules, and School of Chemistry and Chemical Engineering, Hubei
University, Wuhan 430062, P. R. China. Eꢀmail: lfb0615@gmail.com and
liulihubei@gmail.com
†
Electronic supplementary information (ESI) available: NMR spectra of products
2aꢀg, 3, and 5aꢀh, UVꢀvis spectra of 2b and 5f as well as HRMS of 2a and 5a. See
DOI: XXXX
The facile oneꢀstep reaction of [60]fullerene with isocyanates/isothiocyanates in the
presence
of
ferric
perchlorate
generates
a
series
of
oxazolidinofullerenes/thiazolidinofullerenes, which will be difficult to prepare by
common methods. The direct dissolution approach plays an important role in the
efficient synthesis of oxazolidinofullerenes/thiazolidinofullerenes. A possible reaction
mechanism for the product formation is proposed.
Introduction
Since the availability of fullerenes in a macroscopic amount, many chemical reactions
1

Page 3 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
for the functionalization of fullerenes have been explored and numerous fascinating
fullerene derivatives with widely structural diversities have been prepared.1 Radical
reactions2 are one of the first investigated fullerene reactions and are still important
methodologies to functionalize fullerenes.3 Recently, radical reactions of fullerenes
promoted by transition metal salts2,4 such as Mn(OAc)3,5 Fe(ClO4)3,6 FeCl3,7
TBADT[(n–Bu4N)4W10O32],8 Cu(OAc)2,5d,9 Pb(OAc)4,5g,10 CoCl2dppe,11 and
12
Ag2CO3 have attracted extensive attention and have exhibited remarkable
advantages over the traditional peroxideꢀ or lightꢀinitiated processes. Through which,
a large number of novel monoꢀaddition fullerene derivatives have been synthesized.
For instance, the reactions of C60 with nitriles,6a aldehydes/ketones,6b malonate
esters,6c arylboronic acids,6d acid chlorides,6e and βꢀketo esters6f in the presence of
Fe(ClO4)3 afforded the C60ꢀfused oxazoles, C60ꢀfused 1,3ꢀdioxolanes, C60ꢀfused
disubstituted lactones, fullerenyl boronic esters, 1,2ꢀfullerenols, and C60ꢀfused
hemiketal and dihydrofuran, respectively.
Although a large variety of fullerene derivatives have been prepared over the past
two decades, oxazolidinofullerenes/thiazolidinofullerenes are still relatively scarce
until now. Banks13a and Luh13b almost at the same time reported the synthesis of the
first oxazolidinofullerene by chemical transformation of an aziridinofullerene product
from cycloaddition of [60]fullerene (C60) with N3CO2Et. Minakata and coꢀworkers
described the preparation of another four oxazolidinofullerenes by a ringꢀexpansion
reaction of aziridinofullerenes with CO2 catalyzed by PCy3.13c Wang’s group recently
realized the synthesis of seven oxazolidinofullerenes by the FeCl3ꢀcatalyzed reaction
2

RSC Advances
Page 4 of 45
View Article Online
DOI: 10.1039/C4RA10199E
of C60 with tertꢀbutyl Nꢀsubstituted carbamates.7f Among the reported
oxazolidinofullerene derivatives, only those from Wang’s group were prepared
directly from C60. However, the oneꢀstep methodology of Wang’s group mainly
afforded alkylꢀsubstituted oxazolidinofullerenes. As for thiazolidinofullerenes, only
Gan’s group described the synthesis of a few thiazolidinofullerenes through the
reaction of aryl isothiocyanates with fullerene epoxides containing four
tertꢀbutylperoxo groups in the presence of a Lewis acid.14 It should be noted that the
reported methodology for the preparation of thiazolidinofullerenes by Gan et al.
required a multiꢀstep procedure starting from C60 and gave only thiazolidinofullerenes
with
multiple
addends.14
On
the
other
hand,
oxazolidinofullerenes/thiazolidinofullerenes may have promising applications in life
science because oxazolidinones/thiazolidinones have exhibited a wide range of
biological activities.15 Oxazolidinofullerenes/thiazolidinofullerenes are also valuable
precursors for further functionalizations.13a,14 Therefore, it is still demanding to
develop
new
protocol
directly
from
C60
to
obtain
oxazolidinofullerenes/thiazolidinofullerenes, especially the rare arylꢀsubstituted
oxazolidinofullerenes as well as the unreported monoꢀaddition thiazolidinofullerenes,
in a straightforward and efficient way with a broad substrate scope.
In efforts to extend the Fe(ClO4)3ꢀmediated radical reactions of C60, herein we
describe the oneꢀstep reaction of C60 with isocyanates/isothiocyanates promoted by
Fe(ClO4)3 to afford a series of scarce arylꢀsubstituted oxazolidinofullerenes and
monoꢀaddition thiazolidinofullerenes.
3

Page 5 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
Results and discussion
In our previous study, we found that the direct dissolution6aꢀc,6e,6f of Fe(ClO4)3 played
a crucial role for the efficient synthesis of fullerene derivatives. Similarly, we
explored the Fe(ClO4)3ꢀpromoted reaction of C60 with various isocyanates by adopting
the direct dissolution method, i.e., Fe(ClO4)3 was first dissolved in a chosen
isocyanate, and then the dichlorobenzene (ODCB) solution of C60 was added. Much to
our satisfaction, we found that the Fe(ClO4)3ꢀmediated reaction of C60 with
isocyanates 1aꢀg, that is, phenyl isocyanate (1a), 4ꢀtolyl isocyanate (1b),
3ꢀtolyl isocyanate (1c), 4ꢀmethoxyphenyl isocyanate (1d), 3,5ꢀdimethylphenyl
isocyanate (1e), 4ꢀchlorophenyl isocyanate (1f), and 3,4ꢀdichlorophenyl isocyanate
(1g), afforded oxazolidinofullerenes 2aꢀg.
Initially, the reaction of C60 with phenyl isocyanate (1a) in the presence of
Fe(ClO4)3 was chosen to screen the reaction conditions. The details are listed in Table
1. As can be seen from Table 1, the reaction of C60, Fe(ClO4)3, and 1a in a molar ratio
o
of 1:2:20 gave oxazolidinofullerene 2a in 26% of isolated yield at 100 C (entry 1,
Table 1). Decreasing the reaction temperature to 80 oC drastically reduced the isolated
yield of oxazolidinofullerene 2a even by extending the reaction time to 22 h (entry 2,
o
Table 1). Increasing the reaction temperature to 120 C did not improve the yield of
product 2a (entry 3, Table 1). No benefit to the yield of oxazolidinofullerene 2a could
be achieved by variation of the amount of phenyl isocyanate (entries 4ꢀ5, Table 1).
Slight lower yield was obtained by increasing or decreasing the amount of Fe(ClO4)3
(entries 6 and 7 vs entry 1, Table 1). The dissolution of Fe(ClO4)3 in acetonitrile rather
4

RSC Advances
Page 6 of 45
View Article Online
DOI: 10.1039/C4RA10199E
than in 1a lowered the product yield and gave some unknown highly polar byproducts
(entry 8, Table 1). Therefore, the reagent molar ratio of C60/Fe(ClO4)3/1a as 1:2:20
o
and the reaction temperature as 100 C together with the direct dissolution method
were chosen as the optimized reaction conditions. These optimized reaction
conditions could be extended to other isocyanates.
Table 1 Optimization of reaction conditions for the Fe(ClO4)3ꢀmediated reaction of
C60 with phenyl isocyanate 1aa
Fe(ClO4)3
N
O
O
N
C O
,
ODCB, N2
1a
2a
molar
ratiob
temp.
(oC)
100
80
time
(h)
10
22
10
12
11
entry
yield of 2ac
1
2
1:2:20
1:2:20
1:2:20
1:2:10
1:2:30
1:1:20
1:3:20
1:2:20
26% (84%)
2% (67%)
19% (68%)
7% (64%)
21% (54%)
23% (92%)
19% (40%)
14% (32%)
3
120
100
100
100
100
100
4
5
6
12
11
7
8d
13
a All reactions were performed under protection of nitrogen by
the dissolution of Fe(ClO4)3·xH2O in 1a (direct dissolution
b
method) unless otherwise indicated. Molar ratio refers to
C60/Fe(ClO4)3·xH2O/1a. c Isolated yield; those in parentheses
were based on consumed C60. d After the mixture of C60 with
1a was dissolved in oꢀdichlorobenzene (6 mL), 2 mL of
acetonitrile solution of Fe(ClO4)3·xH2O was added at the
reaction temperature.
The reaction times and yields for the Fe(ClO4)3ꢀmediated reaction of C60 with
5

Page 7 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
isocyanates 1aꢀg under the optimized conditions are summarized in Table 2.
Table 2 Reaction times and yields for the reaction of C60 with isocyanates 1a-g in the
a
presence of Fe(ClO4)3
R
Fe(ClO4)3
N
O
O
R
N C O
,
ODCB, N2
1
2
isocyanate 1
time (h)
10
yield of 2b
N
C O
26% (84%)
39% (78%)
30% (91%)
20% (65%)
1a
CH3
N C O
14
24
1b
N
C O
1c
H3C
24c
CH3O
N
C O
1d
H3C
N
C O
24
23% (82%)
1e
H3C
Cl
N
C
C
O
10
5
18% (82%)
9% (41%)
1f
Cl
Cl
N
O
1g
a Unless otherwise indicated, all reactions were performed at
100 oC under nitrogen atmosphere, molar ratio of
b
C60/Fe(ClO4)3·xH2O/1 = 1:2:20. Isolated yield; those in
parentheses were based on consumed C60. c Molar ratio of
C60/Fe(ClO4)3·xH2O/1d = 1:3:20.
As can be seen from Table 2, all of the examined isocyanates 1aꢀg bearing either
electronꢀdonating groups or electronꢀwithdrawing groups could be successfully
utilized to prepare oxazolidinofullerenes 2aꢀg in 9ꢀ39% yields (41ꢀ91% based on
consumed C60), comparable to the previously reported data for most monoadducts. In
the case of 4ꢀmethoxyphenyl isocyanate (1d), increasing the amount of Fe(ClO4)3 to 3
6

RSC Advances
Page 8 of 45
View Article Online
DOI: 10.1039/C4RA10199E
equiv together with prolonging the reaction time to 24 h could provide an acceptable
yield (20%) of oxazolidinofullerene 2d. As for 3,4ꢀdichlorophenyl isocyanate (1g),
some unknown byproducts besides the desired oxazolidinofullerene 2g were produced
for a long reaction time probably attributed to the higher reactivity of 1g owing to the
existence of two electronꢀwithdrawing chloro groups, and thus shorter reaction time
such as 5 h was chosen although the oxazolidinofullerene 2g was obtained only in 9%
yield.
We also investigated the reaction of C60 with 4ꢀnitrophenyl isocyanate (1h) bearing
the stronger electronꢀwithdrawing NO2 group in the presence of Fe(ClO4)3 by the
dissolution of Fe(ClO4)3 in 1h (direct dissolution method), and found that
aziridinofullerene 3 was unexpectedly obtained as the major product in 7% of isolated
yield under standard experimental conditions for 25 h (Scheme 1). The yield of
aziridinofullerene 3 could be increased to 19% (Scheme 1) when the reaction was
conducted by the dissolution of Fe(ClO4)3 in acetonitrile under air conditions for 40 h.
To our disappointment, no anticipated oxazolidinofullerene was isolated from the
above reaction. Very recently, Yang and coꢀworkers have reported the anhydrous
CuCl2ꢀmediated reaction of C60 with 4ꢀnitroaniline under air conditions to afford
aziridinofullerene 3.16 We thus conjectured that the formation of aziridinofullerene 3
should proceed via the Fe(ClO4)3ꢀmediated reaction of C60 with 4ꢀnitroaniline
generated in situ by the addition of H2O in our system to 4ꢀnitrophenyl isocyanate (1h)
accompanied with the elimination of CO2. Controlled experiments indicated that the
reaction of C60, Fe(ClO4)3, and 4ꢀnitroaniline by the dissolution of Fe(ClO4)3 in
7

Page 9 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
o
acetonitrile under air conditions at 150 C for 22 h produced aziridinofullerene 3 in
14% yield (Scheme 1). It should be noted that controlled experiments were also
o
conducted at 100 C. Nevertheless, only a trace amount of aziridinofullerene 3 was
observed even by prolonging the reaction time to 40 h. The difficulty in preparing
aziridinofullerene 3 by the Fe(ClO4)3ꢀmediated reaction of C60 with 4ꢀnitroaniline was
probably attributed to the existence of higher amount of H2O in the reaction system.
In addition, other isocyanates such as tertꢀbutyl isocyanate, cyclohexyl isocyanate,
methylene diphenyl diisocyanate (MDI), and hexamethylene diisocyanate (HDI) have
also be treated with C60 and Fe(ClO4)3 under similar reaction conditions.
Unfortunately, the desired oxazolidinofullerenes could not be successfully isolated.
Fe(ClO4)3
N
NO2
O2N
N C O
ODCB, 100 o
C
1h
7%
3
N2, Fe(ClO4)3 dissolved in 1h
19%
air, Fe(ClO4)3 dissolved in CH3CN
14%
Fe(ClO4)3
NH2
O2N
ODCB, 150 o
C
air, Fe(ClO4)3 dissolved in CH3CN
Scheme 1 Fe(ClO4)3ꢀmediated reaction of C60 with 4ꢀnitrophenyl isocyanate 1h and
4ꢀnitroaniline affording aziridinofullerene 3.
The structures of oxazolidinofullerenes 2aꢀg were fully characterized by HR MS,
1H NMR, 13C NMR, FTꢀIR, and UVꢀvis spectra. All of highꢀresolution mass spectra
of these oxazolidinofullerene products gave the correct molecular ion peaks. Their 1H
NMR spectra displayed the expected chemical shifts as well as the splitting patterns
for all protons. In their 13C NMR spectra, the peak for the C=O carbon appeared at
152.12ꢀ154.51 ppm, and the two sp3ꢀcarbons of the C60 skeleton were located at
8

RSC Advances
Page 10 of 45
View Article Online
DOI: 10.1039/C4RA10199E
91.47ꢀ93.20 ppm and 78.72ꢀ80.17 ppm, close to those of the reported
oxazolidinofullerenes in the previous literature.7f,13 No more than 28 peaks including
some overlapped ones for the 58 sp2ꢀcarbons of the C60 moiety were observed in the
range of 136ꢀ149 ppm, consistent with the Cs symmetry of their molecular structures.
The IR spectra of 2aꢀg showed absorptions at 1768ꢀ1772 cmꢀ1 due to the C=O group.
Their UVꢀvis spectra exhibited a peak at 417ꢀ420 nm, which is a diagnostic
absorption for the 1,2ꢀadduct of C60, to which the oxygen atom is directly
attached.5fꢀh,6c Aziridinofullerene 3 is a known compound and its structure was
confirmed by comparison of its spectral data with those reported previously.16
To expand the scope of the reaction, the substrates were extended from isocyanates
to isothiocyanates. Phenyl isothiocyanate (4a), 4ꢀfluorophenyl isothiocyanate (4b),
4ꢀchlorophenyl
isothiocyanate
(4c), 4ꢀbromophenyl
isothiocyanate
(4d), 4ꢀ(trifluoromethyl)phenyl isothiocyanate (4e), 4ꢀnitrophenyl isothiocyanate (4f),
3ꢀtolyl isothiocyanate (4g), and 4ꢀmethoxyphenyl isothiocyanate (4h) were chosen to
react with C60 in the presence of Fe(ClO4)3 by the direct dissolution method, and were
found to generate thiazolidinofullerenes 5aꢀh.
The reaction conditions were also screened by choosing the reaction of C60 with
phenyl isothiocyanate (4a) promoted by Fe(ClO4)3. The details are listed in Table 3.
As can be seen from Table 3, the reaction of C60 with 50 equiv of phenyl
isothiocyanate in the presence of 5 equiv of Fe(ClO4)3 afforded thiazolidinofullerene
5a in 18% of isolated yield at 100 °C for 18 h (entry 1, Table 3). Decreasing the
reaction temperature to 80 oC or increasing the reaction temperature to 120 oC had no
9

Page 11 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
benefit to the isolated yield of product 5a (entries 2 and 3, Table 3). The variation of
the amount of phenyl isothiocyanate and Fe(ClO4)3 did not improve the isolated yield
of thiazolidinofullerene 5a (entries 4ꢀ7, Table 3). The dissolution of Fe(ClO4)3 in
acetonitrile rather than in 4a obviously reduced the isolated yield of
thiazolidinofullerene 5a even by extending the reaction time to 24 h (entry 8, Table 3).
Accordingly, the best molar ratio of C60:Fe(ClO4)3·xH2O:4a was 1:5:50, and the
reaction temperature was 100 °C. These optimized reaction conditions could also be
extended to other isothiocyanates.
Table 3 Optimization of reaction conditions for the Fe(ClO4)3ꢀmediated reaction of
C60 with phenyl isothiocyanate 4aa
Fe(ClO4)3
N
S
O
N
C S
, ODCB, N2
4a
5a
molar
ratiob
temp.
time
(h)
18
24
2
entry
yield of 5ac
(oC)
100
80
1
2
1:5:50
1:5:50
1:5:50
1:5:30
18% (33%)
7% (88%)
16% (34%)
12% (27%)
18% (28%)
9% (47%)
18% (23%)
5% (11%)
3
120
100
100
100
100
100
4
6
5
1:5:100
1:3:50
1:7:50
1:5:50
7
6
24
5
7
8d
24
a All reactions were performed under nitrogen conditions by
the dissolution of Fe(ClO4)3·xH2O in 4a (direct dissolution
b
method) unless otherwise indicated. Molar ratio refers to
C60/Fe(ClO4)3·xH2O/4a. c Isolated yield; those in parentheses
were based on consumed C60. d After the mixture of C60 with
4a was dissolved in oꢀdichlorobenzene (6 mL), 2 mL of
acetonitrile solution of Fe(ClO4)3·xH2O was added at the
reaction temperature.
10

RSC Advances
Page 12 of 45
View Article Online
DOI: 10.1039/C4RA10199E
The reaction times and yields for the Fe(ClO4)3ꢀmediated reaction of C60 with
isothiocyanates 4aꢀh under the optimized conditions are summarized in Table 4.
Table 4 Reaction times and yields for the reaction of C60 with isothiocyanates 4a-h in
a
the presence of Fe(ClO4)3
R
Fe(ClO4)3
N
S
O
R
N C S
, ODCB, N2
4
5
isocyanate 1
time (h)
18
yield of 2b
N
C S
18% (33%)
4a
F
N
C
S
4
1
25% (81%)
66% (96%)
59% (82%)
4b
Cl
N
C
S
4c
Br
N
C
S
0.5
4d
CF3
N C S
2
26% (62%)
15% (19%)
4e
Ο2Ν
N
C
S
0.5c
4f
N
C S
4
18% (58%)
11% (19%)
4g
H3C
CH3O
N
C
S
14
4h
a
Unless otherwise indicated, all reactions were
o
performed at 100 C under nitrogen atmosphere, molar
ratio of C60/Fe(ClO4)3·xH2O/4 = 1:5:50. b Isolated yield;
c
those in parentheses were based on consumed C60.
Molar ratio of C60/Fe(ClO4)3·xH2O/4f = 1:2:20 and the
reaction temperature = 150 oC.
As can be seen from Table 4, aromatic isothiocyanates bearing either
11

Page 13 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
electronꢀwithdrawing or electronꢀdonating groups (4aꢀh) could be successfully
employed to prepare thiazolidinofullerenes in 11ꢀ66% yields (19ꢀ96% based on
consumed C60). For the synthesis of thiazolidinofullerene 5f, higher reaction
temperature was required for the melting of 5f and subsequent dissolution of
Fe(ClO4)3, and thus resulted in the generation of some unknown byproducts even by
decreasing the molar ratio of C60:Fe(ClO4)3·xH2O:4f to 1:2:20. As for
4ꢀmethoxyphenyl isothiocyanate (4h), an unknown byproduct was produced
accompanied with the formation of thiazolidinofullerene 5h, and accordingly gave the
lower product yield. It should be noted the reaction of aliphatic isothiocyanates such
as benzyl isothiocyanate and butyl isothiocyanate under the same conditions was also
investigated, and found that only less than 5% yield of thiazolidinofullerenes were
obtained.
The identities of thiazolidinofullerenes 5aꢀh were unambiguously established by
1
HR MS, H NMR, 13C NMR, FTꢀIR, and UVꢀvis spectra. Comparing the spectra of
5aꢀh with those of 2aꢀg, we found that the peak at 152.12ꢀ154.51 ppm for the C=O
carbon in the 13C NMR spectra of 2aꢀg were shifted downfield to 165.72ꢀ168.87 ppm
in those of 5aꢀh, and the peaks at 91.47ꢀ93.20 ppm and 78.72ꢀ80.17 ppm for the two
sp3ꢀcarbons of the C60 skeleton were shifted upfield to 82.62ꢀ84.17 ppm and
65.38ꢀ67.07 ppm in those of 5aꢀh; the absorptions at 1768ꢀ1772 cmꢀ1 for the carbonyl
group in the IR spectra of 2aꢀg moved to 1678ꢀ1689 cmꢀ1 in those of 5aꢀh. The
change of the above data agrees well with reported data in the literature.7f,13,14
In our previous study, we have found that C60O could be formed via the reaction of
12

RSC Advances
Page 14 of 45
View Article Online
DOI: 10.1039/C4RA10199E
5d
C60 with metal oxidants such as Mn(OAc)3 under air conditions. To avoid the
formation of C60O, the reaction of C60 with various organic compounds promoted by
6
metal oxidants such as Fe(ClO4)3 has been manipulated under nitrogen atmosphere in
our subsequent study. Therefore, the reaction pathway for the formation of
oxazolidinofullerenes/thiazolidinofullerenes 2/5 by the Fe(ClO4)3ꢀmediated reaction
of C60O with isocyanates/isothiocyanates may be excluded under nitrogen atmosphere
although the study on the reaction of epoxides with isocyanates/isothiocyanates
promoted by different
species to result in the
generation of
oxazolidinones/thiazolidinoes has been reported by different groups.14,17 To further
confirm the plausibility of the aboveꢀmentioned conclusion, controlled experiments
were also conducted via the reaction of C60 with 3,5ꢀdimethylphenyl isocyanate (1e)
and 4ꢀfluorophenyl isothiocyanate (4b) promoted by Fe(ClO4)3 under air conditions
(Scheme 2). Experimental results showed that oxazolidinofullerene 2e was isolated
only in 16% yield when the reaction of C60 with 3,5ꢀdimethylphenyl isocyanate (1e)
was carried out at 100 oC for 24 h, which are obviously lower than that obtained under
o
nitrogen conditions at 100 C for 24 h (23%, Table 2). As for 4ꢀfluorophenyl
isothiocyanate (4b), the reaction under air conditions produced 12% yield of
o
thiazolidinofullerene 5b at 100 C for 4 h, which are also obviously lower than that
obtained under nitrogen conditions at 100 oC for 4 h (25%, Table 4).
13

Page 15 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
H3C
CH3
H3C
H3C
Fe(ClO4)3
air, ODCB
100 oC, 24 h
N
O
O
N
C O
1e
2e
16%
F
Fe(ClO4)3
N
O
S
F
N C S
air, ODCB
100 oC, 4 h
12%
4b
5b
Scheme 2 Fe(ClO4)3ꢀmediated reaction of C60 with 3,5ꢀdimethylphenyl isocyanate 1e
and 4ꢀfluorophenyl isothiocyanate 4b under air conditions.
On the basis of the previously suggested mechanisms for the reactions of C60 with
nitriles,6a aldehydes/ketones,6b arylboronic acids,6d and acid chlorides6e in the
presence of Fe(ClO4)3 together with the reported results from the reactions18 of
isocyanates with active hydrogen compounds such as H2O to selectively afford
carbonyl derivatives, we propose
a
possible formation mechanism for
oxazolidinofullerenes/thiazolidinofullerenes 2/5 from the reaction of C60 with
isocyanates/isothiocyanates 1/4 promoted by Fe(ClO4)3 (Scheme 3, path a). A chosen
isocyanate or isothiocyanate reacts with the hydrated water in Fe(ClO4)3·xH2O or
traces of water in the system to produce Fe(III)ꢀcomplex 6 accompanied with the
elimination of HClO4, and then isomerization to form the more stable Fe(III)ꢀcomplex
7. The observed reddening of the mixtures of isocyanates/isothiocyanates and
Fe(ClO4)3·xH2O hints the formation of complexes between Fe(ClO4)3·xH2O and
isocyanates/isothiocyanates.19 Homolytical addition of 7 to C60 produces fullerenyl
radical 8 with an elimination of Fe(ClO4)2, followed by coordination with another
14

RSC Advances
Page 16 of 45
View Article Online
DOI: 10.1039/C4RA10199E
molecule of Fe(ClO4)3·xH2O to generate Fe(III)ꢀcomplex 9, which undergoes
intramolecular cyclization with the loss of Fe(II) species to afford
a
oxazolidinofullerenes/thiazolidinofullerenes 2/5. It should be noted that the formation
of Fe(III)ꢀcomplex 10 by the reaction of H2O with carbon–nitrogen double bond of
isocyanate in the presence of Fe(ClO4)3 is also possible (Scheme 3, path b), and then
addition of 10 to C60 produces fullerenyl radical 11, which undergoes coordination
with another molecule of Fe(ClO4)3·xH2O to afford Fe(III)ꢀcomplex 12, followed by
intramolecular cyclization to give oxazolidinofullerenes 2. As for isothiocyanates, the
reaction pathway by addition of H2O to carbon–nitrogen double bond of
isothiocyanate could not afford the corresponding thiazolidinofullerenes 5, and was
thus excluded. The exact reason for the exclusive addition of H2O to carbon–sulphur
double bond of isothiocyanate to afford thiazolidinofullerenes 5 is not quite clear now.
Additionally, an oxidative reaction pathway for the formation of
oxazolidinofullerenes/thiazolidinofullerenes should also be mentioned, that is,
fullerenyl radicals 8 and 11 with the aid of Fe(ClO4)3·xH2O could be oxidized to the
corresponding fullerenyl cations, followed by cyclization with the loss of H+ to give
the 2/5.
15

Page 17 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
H
R
XFe(III) C60
XFe(III)
OH
Path a
isomerization
N
R
N
Fe(ClO4)2
HClO4
X = O, S
O
6
7
X
R
O
X
O Fe(ClO4)3
Fe(ClO4)2
N
N
HClO4
H
Fe(III)
R
9
8
Fe(ClO4)3
H2O
R
N
C
X
R
1/4
R
N
O
O
Fe(ClO4)2
N
O
X
Fe(III)
12
Fe(ClO4)3 HClO4
2/5
R
Fe(III)
O
C60
Fe(ClO4)2
N
O
Path b
N
OH
HClO4
X = O
OH
R
10
11
Scheme
3
Proposed
possible
formation
mechanism
for
oxazolidinofullerenes/thiazolidinofullerenes 2/5.
Conclusion
We have synthesized a series of oxazolidinofullerenes/thiazolidinofullerenes via the
Fe(ClO4)3ꢀmediated reaction of C60 with isocyanates/isothiocyanates. The current
oneꢀstep approach to the preparation of oxazolidinofullerenes/thiazolidinofullerenes
was obviously more straightforward and practical than the previously reported
protocols.13,14 The direct dissolution of isocyanates/isothiocyanates and Fe(ClO4)3
proved
to
be
crucial
for
the
efficient
synthesis
of
oxazolidinofullerenes/thiazolidinofullerenes. A plausible reaction mechanism for the
formation of oxazolidinofullerenes/thiazolidinofullerenes is suggested.
Experimental section
16

RSC Advances
Page 18 of 45
View Article Online
DOI: 10.1039/C4RA10199E
General procedure for the Fe(ClO4)3-mediated reaction of C60 with isocyanates
1a-g
A mixture of isocyanate 1a (1b-g, 1.0 mmol) and Fe(ClO4)3·xH2O (0.10 mmol, 0.15
mmol in the case of 1d) was added to a 50ꢀmL threeꢀneck flask equipped with a reflux
condenser, nitrogen inlet and outlet, and a magnetic stirrer. The mixture was heated in
o
an oil bath preset at 100 C for 10 min to allow ferric perchlorate to dissolve in the
liquid isocyanate. Then to the flask was added the oꢀdichlorobenzene (6 mL) solution
of C60 (36.0 mg, 0.05 mmol). The resulting solution was heated with vigorous stirring
in the oil bath at the same temperature under nitrogen atmosphere. The reaction was
carefully monitored by thinꢀlayer chromatography (TLC) and stopped at the
designated time. The resulting solution was directly separated on a silica gel column
with carbon disulfide/toluene as the eluent. Oxazolidinofullerene 2a (2b-g) was
obtained along with unreacted C60.
Fe(ClO4)3-mediated reaction of C60 with phenyl isocyanate 1a by the dissolution
of Fe(ClO4)3 in 1a under different conditions
Fe(ClO4)3·xH2O (0.05ꢀ0.15 mmol) and 1a (0.5ꢀ1.5 mmol) was added to a 50ꢀmL
threeꢀneck flask, which was equipped with a reflux condenser, nitrogen inlet and
outlet, and a magnetic stirrer. The mixture was heated in an oil bath preset at desired
temperature (80ꢀ120 oC) for 10 min to allow Fe(ClO4)3·xH2O to dissolve in liquid 1a.
Then to the flask was added oꢀdichlorobenzene (6 mL) solution of C60 (36.0 mg, 0.05
mmol). The reaction mixture was vigorously stirred in the oil bath preset at the same
17

Page 19 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
temperature under nitrogen atmosphere. The reaction was monitored by TLC and
stopped at the designated time (10ꢀ22 h). The resulting solution was directly separated
on a silica gel column with carbon disulfide/toluene as the eluent to give unreacted
C60 and oxazolidinofullerene 2a.
Fe(ClO4)3-mediated reaction of C60 with phenyl isocyanate 1a by the dissolution
of Fe(ClO4)3 in acetonitrile
A mixture of C60 (36.0 mg, 0.05 mmol) and 1a (108 ꢁL, 1.0 mmol) was dissolved in
oꢀdichlorobenzene (6 mL), and then the resulting solution was deoxygenated by a
nitrogen stream for 10 min. After Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol, dissolved in
2 mL of acetonitrile) was added, the reaction mixture was vigorously stirred at 100 oC
under nitrogen atmosphere for 13 h. The resulting solution was directly separated on a
silica gel column with carbon disulfide/toluene as the eluent to give first unreacted
C60 (20.0 mg, 56%) and then oxazolidinofullerene 2a (6.0 mg, 14%).
Synthesis of oxazolidinofullerene 2a
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1a
(108 ꢁL, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 10 h afforded first
unreacted C60 (24.9 mg, 69%) and then 2a (11.2 mg, 26%) as amorphous black solid.
mp > 300 oC; 1H NMR (600 MHz, CS2/DMSOꢀd6) δ 7.80 (d, J = 7.4 Hz, 2H), 7.55 (t,
J = 7.5 Hz, 2H), 7.48 (t, J = 7.1 Hz, 1H); 13C NMR (125 MHz, CS2/DMSOꢀd6) (all 2C
unless indicated) δ 152.19 (1C, C=O ), 147.32 (1C), 147.11 (1C), 145.48 (4C), 145.43,
18

RSC Advances
Page 20 of 45
View Article Online
DOI: 10.1039/C4RA10199E
145.21 (6C), 144.30, 144.14, 144.11 (4C), 143.96, 143.63, 143.53, 143.47, 143.41,
141.79, 141.72 (4C), 141.36, 141.27, 141.03, 140.98, 140.79, 140.51, 138.92, 138.59,
136.57, 136.24, 134.61 (1C, aryl C), 128.89 (aryl C), 128.66 (aryl C), 128.14 (1C,
aryl C), 91.51 (1C, sp3ꢀC of C60), 78.72 (1C, sp3ꢀC of C60); FTꢀIR ν/cmꢀ1 (KBr) 1771,
1506, 1451, 1430, 1361, 1343, 1227, 1172, 1153, 1087, 1071, 1060, 1016, 954, 857,
832, 738, 689, 546, 525; UVꢀvis (CHCl3) λmax/nm 257, 318, 417; HRMS
(MALDIꢀTOFꢀMS with 4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix) m/z calcd for
C67H5NO2 [M+] 855.0320, found 855.0308.
Synthesis of oxazolidinofullerene 2b
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1b
(135 ꢁL, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 14 h afforded first
unreacted C60 (18.1 mg, 50%) and then 2b (17.1 mg, 39%) as amorphous black solid.
mp > 300 oC; 1H NMR (600 MHz, CS2/CDCl3) δ 7.63 (d, J = 7.8 Hz, 2H), 7.32 (d, J =
7.8 Hz, 2H), 2.42 (s, 3H); 13C NMR (125 MHz, CS2/DMSOꢀd6) (all 2C unless
indicated) δ 152.31 (1C, C=O ), 147.41 (1C), 147.19 (1C), 145.56 (4C), 145.51,
145.30 (4C), 145.27, 144.39, 144.30, 144.23, 144.19, 144.12, 143.71, 143.70, 143.58,
143.51, 141.88, 141.82, 141.80, 141.45, 141.35, 141.11, 141.09, 140.88, 140.61,
139.00, 138.67, 138.18 (1C, aryl C), 136.65, 136.27, 132.07 (1C, aryl C), 129.42 (aryl
C), 128.87 (aryl C), 91.47 (1C, sp3ꢀC of C60), 78.90 (1C, sp3ꢀC of C60), 20.64 (1C);
FTꢀIR ν/cmꢀ1 (KBr) 2916, 2849, 1772, 1512, 1435, 1364, 1352, 1231, 1172, 1155,
1086, 1061, 1014, 954, 864, 809, 793, 742, 546, 526; UVꢀvis (CHCl3) λmax/nm 257,
19

Page 21 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
319, 420; HRMS (MALDIꢀTOFꢀMS with 4ꢀhydroxyꢀαꢀcyanocinnamic acid as the
matrix) m/z calcd for C68H7NO2 [M+] 869.0477, found 869.0472.
Synthesis of oxazolidinofullerene 2c
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1c
(135 ꢁL, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 24 h afforded first
unreacted C60 (24.1 mg, 67%) and then 2c (10.2 mg, 30%) as amorphous black solid.
mp > 300 oC; 1H NMR (600 MHz, CS2/DMSOꢀd6) δ 7.55 (s, 1H), 7.54 (d, J = 7.6 Hz,
1H), 7.37 (t, J = 7.6 Hz, 1H), 7.25 (d, J = 7.4 Hz, 1H), 2.45 (s, 3H); 13C NMR (125
MHz, CS2/DMSOꢀd6) (all 2C unless indicated) δ 152.24 (1C, C=O ), 147.32 (1C),
147.10 (1C), 145.47 (4C), 145.42, 145.21 (4C), 145.19, 144.30, 144.17, 144.14,
144.10, 143.98, 143.62, 143.57, 143.46, 143.41, 141.78, 141.72 (4C), 141.35, 141.26,
141.03, 140.98, 140.78, 140.50, 138.91, 138.67 (1C, aryl C), 138.58, 136.56, 136.18,
134.52 (1C, aryl C), 129.48 (1C, aryl C), 128.97 (1C, aryl C), 128.46 (1C, aryl C),
125.83 (1C, aryl C), 91.47 (1C, sp3ꢀC of C60), 78.73 (1C, sp3ꢀC of C60), 20.60 (1C);
FTꢀIR ν/cmꢀ1 (KBr) 2916, 2848, 1771, 1605, 1488, 1425, 1363, 1350, 1281, 1246,
1188, 1167, 1151, 1086, 1064, 1011, 955, 887, 807, 777, 742, 693, 574, 562, 553, 526;
UVꢀvis (CHCl3) λmax/nm 257, 319, 418; HRMS (MALDIꢀTOFꢀMS with
4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix) m/z calcd for C68H7NO2 [M+]
869.0477, found 869.0476.
Synthesis of oxazolidinofullerene 2d
20

RSC Advances
Page 22 of 45
View Article Online
DOI: 10.1039/C4RA10199E
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1d
(149 mg, 1.0 mmol) and Fe(ClO4)3·xH2O (69.0 mg, 0.15 mmol) for 24 h afforded first
unreacted C60 (24.9 mg, 69%) and then 2d (8.9 mg, 20%) as amorphous black solid.
mp > 300 oC; 1H NMR (500 MHz, CS2/CDCl3) δ 7.66 (d, J = 8.9 Hz, 2H), 7.01 (d, J =
13
8.9 Hz, 2H), 3.83 (s, 3H); C NMR (125 MHz, CS2/CDCl3) (all 2C unless indicated)
δ 160.08 (1C, aryl C), 154.38 (1C, C=O ), 148.37 (1C), 148.16 (1C), 146.55, 146.51,
146.48, 145.26 (4C), 146.24, 145.26, 145.19, 145.15, 144.98, 144.82, 144.64, 144.52,
144.48, 144.40, 142.83, 142.75 (4C), 142.39, 142.29, 142.03, 142.01, 141.82, 141.51,
139.97, 139.70, 137.41, 137.04, 130.96 (aryl C), 127.72 (1C, aryl C), 114.99 (aryl C),
92.65 (1C, sp3ꢀC of C60), 80.17 (1C, sp3ꢀC of C60), 55.19 (1C); FTꢀIR ν/cmꢀ1 (KBr)
2973, 2927, 1769, 1607, 1510, 1459,1435, 1369, 1301, 1252, 1169, 1155, 1087, 1049,
1030, 1012, 954, 864, 828, 742, 628, 547, 526; UVꢀvis (CHCl3) λmax/nm 258, 318,
417; HRMS (MALDIꢀTOFꢀMS with 4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix)
m/z calcd for C68H7NO3 [M+] 885.0426, found 885.0429.
Synthesis of oxazolidinofullerene 2e
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1e
(141 ꢁL, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 24 h afforded first
unreacted C60 (25.9 mg, 72%) and then 2e (10.1 mg, 23%) as amorphous black solid.
o
1
mp > 300 C; H NMR (600 MHz, CS2/CDCl3) δ 7.35(s, 2H), 7.08 (s, 1H), 2.39 (s,
6H); 13C NMR (100 MHz, CS2/CDCl3) (all 2C unless indicated) δ 154.51 (1C, C=O ),
148.37 (1C), 148.17 (1C), 146.54, 146.51, 146.47, 146.26 (4C), 146.24, 145.27,
21

Page 23 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
145.19, 145.14, 144.95, 144.76, 144.63, 144.52, 144.46, 144.39, 142.82, 142.75 (4C),
142.38, 142.29, 142.04, 142.00, 141.80, 141.48, 139.98, 139.66, 139.57 (aryl C),
137.42, 136.98, 135.01 (1C, aryl C), 131.23 (1C, aryl C), 127.26 (aryl C), 92.86 (1C,
sp3ꢀC of C60), 79.99 (1C, sp3ꢀC of C60), 21.42; FTꢀIR ν/cmꢀ1 (KBr) 2917, 2850, 1771,
1611, 1465, 1435, 1366, 1277, 1230, 1195, 1151, 1088, 1014, 956, 851, 797, 764, 690,
575, 527; UVꢀvis (CHCl3) λmax/nm 258, 318, 418; HRMS (MALDIꢀTOFꢀMS with
4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix) m/z calcd for C69H9NO2 [M+]
883.0633, found 883.0641.
Synthesis of oxazolidinofullerene 2f
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1f
(154 mg, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 10 h afforded first
unreacted C60 (28.1 mg, 78%) and then 2f (8.1 mg, 18%) as amorphous black solid.
mp > 300 oC; 1H NMR (600 MHz, CS2/DMSOꢀd6) δ 7.79 (d, J = 8.5 Hz, 2H), 7.48 (d,
J = 8.5Hz, 2H); 13C NMR (125 MHz, CS2/DMSOꢀd6) (all 2C unless indicated) δ
152.13 (1C, C=O ), 147.33 (1C), 147.11 (1C), 145.48 (4C), 145.43, 145.23 (6C),
144.26, 144.13 (4C), 143.77, 143.73, 143.62, 143.39 (6C), 141.80, 141.73 (4C),
141.35, 141.25, 141.02, 140.91, 140.81, 140.45, 138.92, 138.65, 136.62, 136.43,
134.45 (1C, aryl C), 133.16 (1C, aryl C), 130.29 (aryl C), 128.88 (aryl C), 91.62 (1C,
sp3ꢀC of C60), 78.57 (1C, sp3ꢀC of C60); FTꢀIR ν/cmꢀ1 (KBr) 1768, 1490, 1424, 1363,
1349, 1229, 1175, 1154, 1087, 1061, 1010, 953, 863, 820, 810, 736, 725, 541, 526;
UVꢀvis (CHCl3) λmax/nm 257, 318, 419; HRMS (MALDIꢀTOFꢀMS with
22

RSC Advances
Page 24 of 45
View Article Online
DOI: 10.1039/C4RA10199E
4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix) m/z calcd for C67H4ClNO2 [M+]
888.9931, found 888.9937.
Synthesis of oxazolidinofullerene 2g
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 1g
(188 mg, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 5 h afforded first
unreacted C60 (28.2 mg, 78%) and then 2g (4.1 mg, 9%) as amorphous black solid.
mp > 300 oC; 1H NMR (600 MHz, CS2/DMSOꢀd6) δ 8.07 (s, 1H), 7.78 (d, J = 8.5 Hz,
1H), 7.62 (d, J = 8.5 Hz, 1H); 13C NMR (125 MHz, CS2/CDCl3) (all 2C unless
indicated) δ 153.86 (1C, C=O ), 148.41 (1C), 148.21 (1C), 146.58, 146.53 (4C),
146.38, 146.32 (4C), 145.21 (4C), 145.18, 144.65, 144.35, 144.32, 144.27, 144.05
(4C), 142.89, 142.80 (4C), 142.39, 142.31, 142.03, 141.88 (4C), 141.42, 140.06,
139.82, 137.30, 137.29, 134.72 (1C, aryl C), 134.16 (1C, aryl C), 134.10 (1C, aryl C),
131.47 (1C, aryl C), 131.30 (1C, aryl C), 128.66 (1C, aryl C), 93.20 (1C, sp3ꢀC of
C60), 79.55 (1C, sp3ꢀC of C60); FTꢀIR ν/cmꢀ1 (KBr) 1769, 1587, 1506, 1470, 1435,
1345, 1226, 1177, 1155, 1086, 1011, 954, 866, 765, 562, 541, 526; UVꢀvis (CHCl3)
λ
max/nm 257, 319, 417; HRMS (MALDIꢀTOFꢀMS with 4ꢀhydroxyꢀαꢀcyanocinnamic
acid as the matrix) m/z calcd for C67H3Cl2NO2 [M+] 922.9541, found 922.9539.
Fe(ClO4)3-mediated reaction of C60 with 4-nitrophenyl isocyanate 1h by the
dissolution of Fe(ClO4)3 in 1h under nitrogen conditions
According to the general procedure for the preparation of oxazolidinofullerenes 2a-g,
23

Page 25 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
the reaction of C60 (36.0 mg, 0.05 mmol) with 1h (164 mg, 1.0 mmol) and
Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) for 25 h afforded first unreacted C60 (28.2 mg,
78%) and then aziridinofullerene 316 (3.1 mg, 7%).
Fe(ClO4)3-mediated reaction of C60 with 4-nitrophenyl isocyanate 1h by the
dissolution of Fe(ClO4)3 in acetonitrile under air conditions
A mixture of C60 (36.0 mg, 0.05 mmol) and 1h (164 mg, 1.0 mmol) was dissolved in
oꢀdichlorobenzene (6 mL). After Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol, dissolved in 2
o
mL of acetonitrile) was added, the reaction mixture was vigorously stirred at 100 C
under air conditions for 40 h. The reaction mixture was passed through a silica gel
plug to remove any insoluble material. After the solvent was evaporated in vacuo, the
residue was separated on a silica gel column with carbon disulfide/toluene as the
eluent to give unreacted C60 (28.0 mg, 78%) and then aziridinofullerene 316 (8.1 mg,
19%).
Fe(ClO4)3-mediated reaction of C60 with 4-nitroaniline by the dissolution of
Fe(ClO4)3 in acetonitrile under air conditions
According to the same procedure as for the preparation of aziridinofullerene 3 by
4ꢀnitrophenyl isocyanate 1h under air conditions, the reaction of C60 (36.0 mg, 0.05
mmol) with 4ꢀnitroaniline (138 mg, 1.0 mmol) and Fe(ClO4)3·xH2O (46.0 mg, 0.10
o
mmol) at 150 C for 22 h afforded first unreacted C60 (30.2 mg, 84%) and then
aziridinofullerene 316 (6.0 mg, 14%).
24

RSC Advances
Page 26 of 45
View Article Online
DOI: 10.1039/C4RA10199E
Fe(ClO4)3-mediated reaction of C60 with 3,5-dimethylphenyl isocyanate 1e by the
dissolution of Fe(ClO4)3 in 1e under air conditions
A mixture of 3,5ꢀdimethylphenyl isocyanate 1e (141 ꢁL, 1.0 mmol) and
Fe(ClO4)3·xH2O (46.0 mg, 0.10 mmol) was added to a 50ꢀmL roundꢀbottom flask,
which was heated in an oil bath preset at 100 oC for 10 min to allow ferric perchlorate
to dissolve in the liquid isocyanate. Then to the flask was added the
oꢀdichlorobenzene (6 mL) solution of C60 (36.0 mg, 0.05 mmol). The reaction mixture
was vigorously stirred in the oil bath at the same temperature under air conditions for
24 h. The resulting solution was directly separated on a silica gel column with carbon
disulfide/toluene as the eluent to give unreacted C60 (27.9 mg, 78%) and then
oxazolidinofullerene 2e (7.1 mg, 16%).
General procedure for the Fe(ClO4)3-mediated reaction of C60 with
isothiocyanates 4a-h.
A mixture of isothiocyanate 4a (4b-h, 2.5 mmol, 1.0 mmol in the case of 4f) and
Fe(ClO4)3·xH2O (0.25 mmol, 0.10 mmol in the case of 4f) was added to a 50ꢀmL
threeꢀneck flask equipped with a reflux condenser, nitrogen inlet and outlet, and a
magnetic stirrer. The mixture was heated in an oil bath preset at 100 oC (150 oC in the
case of 4f) for 10 min to allow ferric perchlorate to dissolve in the liquid
isothiocyanate. Then to the flask was added the oꢀdichlorobenzene (6 mL) solution of
C60 (36.0 mg, 0.05 mmol). The resulting solution was heated with vigorous stirring in
25

Page 27 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
the oil bath at the same temperature under nitrogen atmosphere. The reaction was
carefully monitored by thinꢀlayer chromatography (TLC) and stopped at the
designated time. The reaction mixture was passed through a silica gel plug to remove
any insoluble material. After the solvent was evaporated in vacuo, the residue was
separated on a silica gel column with carbon disulfide/toluene as the eluent.
Thiazolidinofullerene 5a (5b-h) was obtained along with unreacted C60.
Fe(ClO4)3-mediated reaction of C60 with phenyl isothiocyanate 4a by the
dissolution of Fe(ClO4)3 in 4a under different conditions.
Fe(ClO4)3·xH2O (0.15ꢀ0.35 mmol) and 1a (1.5ꢀ5.0 mmol) was added to a 50ꢀmL
threeꢀneck flask, which was equipped with a reflux condenser, nitrogen inlet and
outlet, and a magnetic stirrer. The mixture was heated in an oil bath preset at desired
temperature (80ꢀ120 oC) for 10 min to allow Fe(ClO4)3·xH2O to dissolve in liquid 4a.
Then to the flask was added oꢀdichlorobenzene (6 mL) solution of C60 (36.0 mg, 0.05
mmol). The reaction mixture was vigorously stirred in the oil bath preset at the same
temperature under nitrogen atmosphere. The reaction was monitored by TLC and
stopped at the designated time (2ꢀ24 h). The resulting solution was passed through a
silica gel plug to remove any insoluble material. After the solvent was evaporated in
vacuo, the residue was separated on a silica gel column with carbon disulfide/toluene
as the eluent to give unreacted C60 and thiazolidinofullerene 5a.
Fe(ClO4)3-mediated reaction of C60 with phenyl isothiocyanate 4a by the
26

RSC Advances
Page 28 of 45
View Article Online
DOI: 10.1039/C4RA10199E
dissolution of Fe(ClO4)3 in acetonitrile.
A mixture of C60 (36.0 mg, 0.05 mmol) and 4a (296 ꢁL, 2.5 mmol) was dissolved in
oꢀdichlorobenzene (6 mL), and then the resulting solution was deoxygenated by a
nitrogen stream for 10 min. After Fe(ClO4)3·xH2O (115.0 mg, 0.25 mmol, dissolved in
2 mL of acetonitrile) was added, the reaction mixture was vigorously stirred at 100 oC
under nitrogen atmosphere for 24 h. The resulting solution was passed through a silica
gel plug to remove any insoluble material. After the solvent was evaporated in vacuo,
the residue was separated on a silica gel column with carbon disulfide/toluene as the
eluent to give first unreacted C60 (19.2 mg, 53%) and then thiazolidinofullerene 5a
(2.3 mg, 5%).
Synthesis of thiazolidinofullerene 5a.
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 4a
(296 ꢁL, 2.5 mmol) and Fe(ClO4)3·xH2O (115.0 mg, 0.25 mmol) for 18 h afforded
first unreacted C60 (16.1 mg, 45%) and then 5a (8.0 mg, 18%) as amorphous black
solid. mp > 300 oC; 1H NMR (500 MHz, CS2/CDCl3) δ 7.63 (d, J = 7.8 Hz, 2H), 7.50
(t, J = 7.6 Hz, 2H), 7.44 (t, J = 7.4 Hz, 1H); 13C NMR (125 MHz, CS2/CDCl3) (all 2C
unless indicated) δ 167.75 (1C, C=O), 150.81, 148.18 (1C), 147.87 (1C), 146.54,
146.32, 146.27, 146.19, 146.09, 145.70, 145.56, 145.26, 145.17, 144.69, 144.58,
144.38, 144.28, 143.10, 143.02, 142.76, 142.68, 142.27, 142.16, 142.02, 141.95,
141.60, 141.56, 140.37, 139.17, 137.04 (1C, aryl C), 136.03, 134.34, 131.21 (aryl C),
129.64 (aryl C), 129.54 (1C, aryl C), 84.05 (1C, sp3ꢀC of C60), 66.34 (1C, sp3ꢀC of
27

Page 29 of 45
RSC Advances
View Article Online
DOI: 10.1039/C4RA10199E
C60); FTꢀIR ν/cmꢀ1 (KBr) 2918, 2849, 1678, 1487, 1462, 1431, 1313, 1201, 1180,
1154, 1103, 1069, 1051, 882, 842, 814, 743, 690, 548, 524; UVꢀvis (CHCl3) λmax/nm
258, 319, 422; HRMS (MALDIꢀTOFꢀMS with 4ꢀhydroxyꢀαꢀcyanocinnamic acid as
the matrix) m/z calcd for C67H5NOS [M+Na]+ 893.9990, found 893.9990.
Synthesis of thiazolidinofullerene 5b.
According to the general procedure, the reaction of C60 (36.0 mg, 0.05 mmol) with 4b
(308 ꢁL, 2.5 mmol) and Fe(ClO4)3·xH2O (115.0 mg, 0.25 mmol) for 4 h afforded first
unreacted C60 (24.9 mg, 69%) and then 5b (11.1 mg, 25%) as an amorphous black
solid. mp > 300 oC; 1H NMR (500 MHz, CS2/CDCl3) δ 7.63 (dd, J = 8.8, 4.8 Hz, 2H),
7.18 (t, J = 8.4 Hz, 2H); 13C NMR (125 MHz, CS2/CDCl3) (all 2C unless indicated) δ
167.99 (1C, C=O), 162.88 (d, JCꢀF = 251.5 Hz, 1C, aryl C), 150.68, 148.22 (1C),
147.92 (1C), 146.58, 146.37, 146.31, 146.23, 146.16, 145.67, 145.60, 145.31, 145.21,
144.72, 144.31, 144.29, 144.21, 143.07, 143.05, 142.81, 142.72, 142.27, 142.19,
142.03, 141.97, 141.66, 141.54, 140.42, 139.29, 136.14, 134.30, 133.10 (d, JCꢀF = 8.9
Hz, aryl C), 132.89 (d, JCꢀF = 3.4 Hz, 1C, aryl C), 116.80 (d, JCꢀF = 22.8 Hz, aryl C),
83.98 (1C, sp3ꢀC of C60), 66.29 (1C, sp3ꢀC of C60); FTꢀIR ν/cmꢀ1 (KBr) 2918, 2849,
1686, 1596, 1504, 1463, 1434, 1315, 1226, 1199, 1150, 1104, 1090, 1050, 885, 860,
816, 551, 525; UVꢀvis (CHCl3) λmax/nm 257, 319, 421; HRMS (MALDIꢀTOFꢀMS
with 4ꢀhydroxyꢀαꢀcyanocinnamic acid as the matrix) m/z calcd for C67H4FNOS
[M+Na]+ 911.9895, found 911.9884.
28