Reactivity of fullerene epoxide: Preparation of fullerene-fused thiirane, tetrahydrothiazolidin-2-one, and 1,3-dioxolane

Article abstract of DOI:10.1021/jo7023587

(Chemical Equation Presented) The epoxide moiety in the fullerene-mixed peroxide C₆₀(O)(OO^tBu)₄ 1 reacts readily with aryl isocyanates ArNCS (Ar = Ph, Naph) to form both the thiirane derivative C₆₀(S)(OO^t

Full text of DOI:10.1021/jo7023587

Reactivity of Fullerene Epoxide: Preparation of Fullerene-Fused
Thiirane, Tetrahydrothiazolidin-2-one, and 1,3-Dioxolane
Xiaobing Yang,†,§ Shaohua Huang,† Zhenshan Jia,† Zuo Xiao,† Zhongping Jiang,†
Qianyan Zhang,† Liangbing Gan,*,†,‡ Bo Zheng,† Gu Yuan,† and Shiwei Zhang*,†
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Bioorganic Chemistry and
Molecular Engineering of the Ministry of Education, College of Chemistry and Molecular Engineering,
Peking UniVersity, Beijing 100871, China, State Key Laboratory of Organometallic Chemistry, Shanghai
Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China,
and Beijing Institute of Pharmaceutical Chemistry, P.O. Box 925 (West Building), 100083, China
gan@pku.edu.cn; zhangsw@pku.edu.cn
ReceiVed NoVember 1, 2007
The epoxide moiety in the fullerene-mixed peroxide C60(O)(OOtBu)4 1 reacts readily with aryl isocyanates
ArNCS (Ar ) Ph, Naph) to form both the thiirane derivative C60(S)(OOtBu)4 and fullerene-fused
tetrahydrothiazolidin-2-one. The reaction of 1 with trimethylsilyl isothiocyanate TMSNCS yields the
isothiocyanate derivative C60(NCS)(OH)(OOtBu)4, the isothiocyanate and hydroxyl moieties of which
could be converted to a fullerene-fused tetrahydrothiazolidin-2-one ring with alumina quantitatively.
Treating 1 with BF3·Et2O yields the fullerene-fused [1,3,2]-dioxoborolane derivative C60(O2BOH)(OOt-
Bu)4. In the presence of aldehyde or acetone, BF3·Et2O catalyzes the conversion of epoxide to fullerene-
fused 1,3-dioxolane derivatives. The products are characterized by spectroscopic data. Two of the
compounds are also characterized by single-crystal X-ray analysis.
Introduction
detected by mass spectra.1 Isomerically pure bis- and tris-adducts
have been characterized.1d,h,i Several groups have theoretically
investigated the structure of fullerene epoxides.2
Compared to the extensive study on the preparation and
structure of fullerene epoxides, little is known about their further
Fullerene epoxide is one of the first fullerene derivatives. A
number of methods have been reported for their synthesis in
the early days of fullerene chemistry.1 Diederich et al. isolated
C70O from a fullerene mixture generated by resistive heating
of graphite.1a Photooxidation of C60 in oxygenated benzene
solution afforded C60(O) as the sole isolable product.1b Dim-
ethyldioxirane also reacts with C60 to form C60(O) together with
1,3-dioxolane derivatives.1c,d Other methods such as methyltri-
oxorhenium-hydrogen peroxide,1e ozonolysis,1f chemically gen-
erated singlet oxygen,1g and m-chloroperbenzoic acid1h have also
been reported to oxidize fullerenes into fullerene epoxides. The
last method is the most frequently used method because of its
relative high yields. Various multiadducts C60(O)n have been
(1) (a) Diederich, F.; Ettl, R.; Rubin, Y.; Whetten, R. L.; Beck, R.;
Alvarez, M.; Anz, S.; Sensharma, D.; Wudl, F.; Khemani, K. C.; Koch, A.
Science 1991, 252, 548. (b) Creegan, K. M.; Robbins, J. L.; Robbins, W.
K.; Millar, J. M.; Sherwood, R. D.; Tindall, P. J.; Cox, D. M.; Smith, A.
B., III; McCanley, J. P., Jr.; Jones, D. R.; Gallagher, R. T. J. Am. Chem.
Soc. 1992, 114, 1103. (c) Elemes, Y.; Silverman, S. K.; Sheu, C.; Kao, M.;
Foote, C. S.; Alvarez, M. M.; Whetten, R. L. Angew. Chem., Int. Ed. Engl.
1992, 31, 351. (d) Fusco, C.; Seraglia, R.; Curci, R.; Lucchini, V. J. Org.
Chem. 1999, 64, 8363. (e) Murray, R. W.; Iyanar, K. Tetrahedron Lett.
1997, 38, 335. (f) Heymann, D.; Bachilo, S. M.; Weisman, R. B.; Catalo,
F.; Fokkens, R. H.; Nibbering, N. M. M.; Vis, R. D.; Chibante, L. P. F. J.
Am. Chem. Soc. 2000, 122, 11473. (g) Hamano, T.; Okuda, K.; Mashino,
T.; Hirobe, M. J. Chem. Soc., Chem. Commun. 1995, 1537. (h) Tajima, Y.;
Takeuchi, K. J. Org. Chem. 2002, 67, 1696. (i) Balch, A. L.; Costa, D. A.;
Noll, B. C.; Olmstead, M. M. J. Am. Chem. Soc. 1995, 117, 8926. (j) Balch,
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* Author to whom correspondence should be addressed. Fax: 86-10-
62751708.
† Peking University.
‡ Chinese Academy of Sciences.
§ Beijing Institute of Pharmaceutical Chemistry.
10.1021/jo7023587 CCC: $40.75 © 2008 American Chemical Society
Published on Web 03/13/2008
2518
J. Org. Chem. 2008, 73, 2518-2526

Fullerene Epoxide
SCHEME 1. Preparation of Thiirane 3 and
Tetrahydrothiazolidin-2-one 4
functionalization. A major problem hindering the chemistry of
fullerene epoxide is the time-consuming HPLC separation of
the mixture of epoxides C60(O)n resulting from the nonselective
epoxidation reactions. In addition, slow degradation of the
fullerene epoxides adds more difficulty for their functionaliza-
tion. Nevertheless, Tajima et al. succeeded in converting C60-
(O) into 1,3-dioxolane derivatives.3 The same group also
reported the Lewis acid-assisted nucleophilic substitution of C60-
(O) to form 1,4-bisadduct (para-addition).4 Heating a mixture
of C60O1-3 and C60 under various conditions produces both
C
120O and C120O2.5
We have reported the reaction between tert-butylperoxo
radicals and C60 to give the epoxide-containing derivative 1.6
Presence of the tert-butylperoxo groups results in high solubility
and easy purification by flash chromatography. Further study
indicates that compound 1 also shows good chemoselectivity
under mild conditions. The epoxide moiety could be converted
to vicinal diol and halohydrins in good yields by Lewis acids.7
The tert-butylperoxo groups remain unchanged in these reac-
tions, and greatly facilitate product purification and characteriza-
tion. Here we report the transformation of the epoxide moiety
into thiirane and various five-membered heterocyclic derivatives.
Results and Discussion
Reactions of Aryl Isothiocyanates with 1. Sulfur-containing
fullerene derivatives have attracted much attention due to their
interesting photophysical properties.8 Various sulfur-containing
fullerene derivatives have been prepared.9,10 The simplest sulfur-
containing fullerene derivative is the thiirane derivative C60S,
analogous to the well-known fullerene epoxide C60O. It has been
the subject of theoretical calculations,11 which suggested that a
[6,6]-closed structure might be stable relative to dissociation to
C
60 and atomic sulfur or to 2C60 and S2. Heymann et al. observed
C60S- and C60S+ ions in the gas phase by analyzing mixtures
of C60 and elemental sulfur by LDI-TOF.12 But attempted
syntheses were not successful. In an effort to prepare the
fullerene thiirane derivatives, we first tried the reaction between
1 and isothiocyanates.
(2) (a) Raghavachari, K. Chem. Phys. Lett. 1992, 195, 221. (b) Batirev,
I. G.; Lee, K. H.; Lee, W. R.; Lee, H. M.; Leiro, J. A. Chem. Phys. Lett.
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Isothiocyanates are common sulfurating reagents in classical
organic chemistry.13 They react with epoxides to form sulfur
heterocycles under various conditions. The epoxide moiety of
1 readily reacts with aryl isothiocyanate PhNCS in the presence
of TMSOTf to give the epoxide-opened derivative 2 in good
yields (Scheme 1). The reaction and all the purification
procedure were carried out in the dark to avoid photoinduced
decomposition. Other Lewis acids such as BF3 were also tested
but gave lower yields due to formation of other products.
Compound 2 is stable for several hours. The 13C NMR spectra
of both 2a and 2b were quite complex, indicating the presence
of at least two compounds. Possible structures of 2 are shown
in Scheme 1. Upon storage in the dark for several days at r.t.,
(5) (a) Smith, A. B., III; Tokuyama, H.; Strongin, R. M.; Furst, G. T.;
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Zhang, S. W.; Lu, M. J.; Pan, J. Q.; Xu, L. J. Org. Chem. 2004, 69 2442.
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S. W.; Chen, Z. F.; Thiel, W.; Schleyer, P. von R.; Zhang, X.; Hu, X. Q.;
Chen, B. C.; Gan. L. B. Chem. Eur. J. 2005, 11, 5449. (b) Hu, X. Q.;
Jiang, Z. P.; Jia, Z. S.; Huang, S. H.; Yang, X. B.; Li, Y. L.; Gan, L. B.;
Zhang, S. W.; Zhu, D. B. Chem. Eur. J. 2007, 13, 1129. (c) Jia, Z. S.;
Zhang, X.; Zhang, G. H.; Huang, S. H.; Fang, H.; Hu, X. Q.; Li, Y. L.;
Gan, L. B.; Zhang, S. W.; Zhu, D. B. Chem. Asian J. 2007, 2, 290.
(8) Mart´ın, N.; Sa´nchez, L.; Illescas, B.; Pe´rez, I. Chem. ReV. 1998, 98,
2527 and references therein.
(9) (a) Eguchi, S.; Ohno, M.; Kojima, S.; Koide, N.; Yashiro, A.;
Shirakawa, Y.; Ishida, H. Fullerene Sci. Technol. 1996, 4, 303. (b)
Yamazaki, T.; Murata, Y.; Komatsu, K.; Furukawa, K.; Morita, M.;
Maruyama, N.; Yamao, T.; Fujita, S. Org. Lett. 2004, 6, 4865. (c)
Roubelakis, M. M.; Vougioukalakis, G. C.; Orfanopoulos, M. J. Org. Chem.
2007, 72, 6526. (d) Sa´nchez, L.; Herranz, M. AÄ .; Mart´ın, N. J. Mater. Chem.
2005, 15, 1409. (e) Wang, G. W.; Li, J. X.; Li, Y. J.; Liu, Y. C. J. Org.
Chem. 2006, 71, 680. (f) Ioannou, E.; Hirsch, A.; Elemes, Y. Tetrahedron
2007, 63, 7070.
(10) (a) Takaguchi, Y.; Katayose, Y.; Yanagimoto, Y.; Motoyoshiya,
J.; Aoyama, H.; Wakahara, T.; Maeda, Y.; Akasaka, T. Chem. Lett. 2003,
32, 1124. (b) Ohno, M.; Kojima, S.; Shirakawa, Y.; Eguchi, S. Tetrahedron
Lett. 1995, 36, 6899. (c) Ohno, M.; Kojima, S.; Eguchi, S. J. Chem. Soc.,
Chem. Commun. 1995, 565. (d) Duczek, W.; Tittelbach, F.; Costisella, B.;
Niclas, H. J. Tetrahedron 1996, 52, 8733. (e) Bartoszek, M.; Duczek, W.;
Tittelbach, F.; Niclas, H.-J. Synth. Met. 1996, 77, 93. (f) Giesa, S.; Gross,
J. H.; Hull, W. E.; Lebedkin, S.; Gromov, A.; Gleiter, R.; Kra¨tschmer, W.
Chem. Commun. 1999, 465. (g) Murata, Y.; Murata, M.; Komatsu, K. Chem.
Eur. J. 2003, 9, 1600.
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X. Z. J. Phys. Chem. A 2002, 106, 9284.
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3047, and references therein.
J. Org. Chem, Vol. 73, No. 7, 2008 2519

Yang et al.
TABLE 1. Preparation of Compound 3 and 4 under Different
Conditionsa
SCHEME 3. Formation of Bis-epoxides
entry
Ar
Ph
Ph
Ph
Naph
Naph
conditions
3 (%)
4 (%)
1
2
5
3
4
A
B
C
A
B
80
13
trace
74
23
8
59
79
15
53
a Notes: Reaction conditions: A, compound 2 in CH2Cl2, hν, r.t.; B,
compound 2 stored as powder r.t. in the dark; C, The CH2Cl2/toluene
solution of compound 2a from chromatography without further evaporation
was refluxed in the dark. For A and B, the yields were based on 2; for C,
the yield was based on 1.
SCHEME 2. Preparation of Isothiocyanate 5 and Related
Reactions
SCHEME 4. From Epoxide to Acetal and Borate
it gradually changed into compounds 3 and 4. Exposure of the
phenyl derivative 2 to visible light gave the thiirane derivative
3 as the major product, whereas refluxing its CH2Cl2/toluene
solution in the dark gave 4a as the major product (entries 1-3
in Table 1). Isolation of 2 is necessary to convert it to 3 or 4
efficiently. Heating or irradiating the reaction mixture of 1 and
isothiocyanates led to a complicated mixture of products.
Reaction of Trimethylsilyl Isothiocyanate with 1. Under
similar conditions to the above aryl isothiocyanate reactions,
treatment of 1 with TMSNCS led to different results (Scheme
2). After TLC indicated that most of the starting material 1 was
consumed, the resulting solution was transferred on to silica
gel column. The solution quickly changed from red-orange to
black upon contact with silica gel. The isothiocyanate adduct 5
was eventually eluted out as a red-orange band. In an effort to
avoid the effect of silica gel, the reaction solution was treated
with neutral alumina column. The thiozolidinone derivative 6
was obtained. Treating the thiocyanate 5 with neutral alumina
gave compound 6 in quantitative yield. As expected, treating 6
with benzoyl chloride yielded acylated product 7.
trap for active species resulting from the cleavage of the tert-
butylperoxo groups.
Acetalization of Epoxy Rings with Aldehydes and Acetone.
The epoxy moiety in the present compounds can be readily
converted to 1,3-dioxolane derivatives by treatment with alde-
hyde or acetone in the presence of Lewis acid. The reaction
was faster in dichloromethane than that in benzene. Aromatic
aldehydes with an electron-donating group gave a higher yield
than those with an electron-withdrawing group. Yield of the
aliphatic aldehyde CH3CHO is similar to the aromatic aldehydes
with an electron-donating group at around 51%. The [1,3,2]-
dioxoborolane derivative 11 was formed as a byproduct due to
presence of water. In the absence of aldehyde, excess BF3
etherate reacted with 1 to give the derivative 11 as the major
product (Scheme 4).
Under similar conditions, both the epoxy moieties in com-
pounds 8 and 9 could be acetalized by acetone to form
compound 12 and 13, respectively (Scheme 5). The bisepoxide
and the corresponding bis-1,3-dioxolane derivatives have similar
Rf values on silica gel. To facilitate purification, the reaction
was stopped after all the starting material was consumed. There
Thermolysis of the Thiazolidinone Derivatives. The thia-
zolidinone ring in compound 4 is very stable at r.t. There is
hardly any decomposition after storing the solid for a few weeks.
Upon heating at 110 °C in chlorobenzene, two O-O bonds in
the tert-butylperoxo addends were cleaved to form the diep-
oxides 8 and 9 (Scheme 3). Yields of 8 and 9 were almost the
same for both the phenyl and the naphthenyl derivatives. To
avoid formation of uncharacterizable products, 2 equiv of C60
was added in the solution. The added C60 probably acted as a
2520 J. Org. Chem., Vol. 73, No. 7, 2008

Fullerene Epoxide
SCHEME 5. Formation of Bisacetals
the C60 with a dihedral angle at 87.5°. The longest bond on the
fullerene cage is 1.562 Å at the thiazolidinone fullerene-fusion
bond. The double bonds on the central pentagon are the shortest
among all the fullerene double bonds on the cage at 1.326 and
1.343 Å. The single bond on the central pentagon is 1.460 Å,
which is well within the range of other single bonds on the
fullerene cage. This indicates that the conjugation effect of the
1,4-diene on the central pentagon is negligible.
The structure of 10d shows the dioxolane ring as an envelope
conformation, in which the two oxygen atoms and the two
fullerene carbons are planar. The phenyl ring is at the equatorial
position of the envelope and perpendicular to the envelope plane
with a dihedral angle of 86.0°. The longest bond on the fullerene
cage of 10d is the dioxolane fullerene-fusion bond at 1.576 Å,
which is close to the above thiazolidinone fusion bond in 4a.
Double bonds on the central pentagon are 1.325 and 1.351 Å.
Spectroscopic Data and Structure Assignment. In light of
the above X-ray analysis result, structures of other compounds
were derived from their spectroscopic data. ESI-MS spectra in
the positive mode gave molecular ion signals M + NH4+ or M
+ H+ as the base peak for all the compounds except 8 and 9,
the base peak of which appeared in the negative mode as M +
CH3O-. A mixture of methanol and CDCl3 or CHCl3 was used
in measuring the ESI-MS spectra. The epoxide moiety may be
opened through addition of methanol under the negative-mode
conditions.
Compounds 3, 4a, 5, 6, 7, 8a, 8b, 10f, 11, and 12 are Cs
symmetric. Their 1H and 13C NMR spectra showed the expected
Cs pattern. In their 13C NMR spectra there were 28 signals (a
few of which were overlapped) in the region for sp2 fullerene
carbon atoms and four C (sp3) fullerene signals. Chemical shifts
of the thiirane derivative 3 are almost identical to those of the
corresponding oxirane 1. The two sp3 fullerene carbons con-
necting the four tert-butyl groups appear at 84.0, 81.3 ppm and
84.8, 81.0 ppm, respectively, for compound 3 and the oxirane
1. The only difference is at the three-membered ring. The
thiirane fullerene carbons appear at 52.9, 57.0 ppm, whereas
the oxirane fullerene carbons appear at 75.9, 71.4 ppm.
was no monoacetalization intermediate detected under these
conditions. We have previously reported the reaction of 1 with
CF3COOH to give ortho-ester type 1,3-dioxolane derivative.6b
Treating 8a with CF3COOH gave a mixture of several isomers
1
as indicated by H NMR and ESI-MS.
Several methods have been reported in the literature for the
preparation of fullerene-fused 1,3-dioxolane derivatives. The
above reactions are analogous to the method by Tajima et al.3
who reported mono- and bis-1,3-dioxolane fullerene derivatives
by addition of aldehyde to C60(O) and regioisomerically pure
fullerene diepoxide C60(O)2. Several other methods can also
produce 1,3-dioxolane fullerene derivatives: the formal [2 +
3] cycloaddition of dimethyldioxirane to C60,1c the reaction of
benzyl alcohol with C60 in the presence of air,14 and the addition
of CF3COOI15 or (CF3CO)2OO16 to C60.
Single-Crystal X-ray Structure of 4a and 10d. Various
methods were tried to grow suitable crystals for X-ray diffraction
analysis. Slow evaporation of compound 4a in a mixture of CS2
and ethanol yielded crystals as layered sheets, which contained
some CS2 molecules in the crystals, but the solvent molecules
escaped from the crystals very quickly preventing X-ray
diffraction data collection. To modify the crystallization process,
the crystals were then redissolved in CS2, and some acetonitrile,
CH2Cl2, and ethanol were added. Slow evaporation gave
rectangle crystals. The X-ray diffraction analysis showed the
crystals were twinned and could not be solved. Recrystallization
of the same sample in a mixture of CS2, ethanol, acetonitrile,
and hexafluorobenzene at 5 °C eventually gave suitable crystals
for X-ray analysis. Crystals of 10d were also obtained from a
mixture of CS2, hexane, ethanol, acetonitrile, CH2Cl2, and
hexafluorobenzene at 5 °C.
The relative location of the OH and SCN groups in compound
5 was confirmed by HMBC spectrum. The OH group showed
correlation with the unique central pentagon carbon signal at
155.3 ppm. This is similar to the analogous Cs symmetric
compound C60 (OH)Cl(OOtBu)4, which was characterized by
single-crystal X-ray analysis, and its HMBC spectrum also
showed correlation to the unique central pentagon carbon signal
at 157.3 ppm. But the NMR data could not differentiate between
the two possible isomers for 5, i.e. the thiocyanate with the sulfur
atom attached to the C60 as depicted in Scheme 2 and the
isothiocyanate with the nitrogen atom attached to C60. The
thiocyanate 5 was chosen because the IR spectrum did not show
an intense stretching band in the range from 1500 to 2600 cm-1
which is expected for the RNCS derivative.
,
Crystal structures of 4a (Figure 1) show that the sulfur atom
is attached to the central pentagon, while the nitrogen atom is
located outside. The phenyl ring is perpendicular to the
thiazolidinone ring with a dihedral angle at 85.4°, and the
thiazolidinone ring is perpendicular to the central pentagon on
Compound 6 and its benzyl derivative 7 showed NMR spectra
similar to that of the analogous compound 4a. Since the relative
location of the nitrogen and the sulfur atoms in 4a was
characterized by single-crystal X-ray analysis as discussed
above, it is reasonable to assume that compounds 6 and 7 have
the same addition pattern.
Structure assignments for the C1 symmetric compounds are
less conclusive. The ESI-MS and NMR spectra clearly revealed
what groups are attached on the C60 cage, but the data could
not assign their relative locations unambiguously. Structures of
(14) Wang, G. W.; Shu, L. H.; Wu, S. H.; Wu, H. M.; Lao, X. F. J.
Chem. Soc., Chem. Commun. 1995, 1071.
(15) Troshin, P. A.; Peregudov, A. S.; Lyubovskaya, R. N. Tetrahedron
Lett. 2006, 47, 2969.
(16) Yoshida, M.; Morinaga, Y.; Iyoda, M.; Kikuchi, K.; Ikemoto, I.;
Achiba, Y. Tetrahedron Lett. 1993, 34, 7629.
J. Org. Chem, Vol. 73, No. 7, 2008 2521

Yang et al.
FIGURE 1. Single-crystal X-ray structures of compounds 4a (left) and 10d (right). For clarity, hydrogen atoms on the methyl and phenyl groups
were not shown. Grey, carbon; red, oxygen; blue, nitrogen; green, hydrogen; yellow, sulfur.
SCHEME 6. Proposed Pathway for the Formation of Compounds 3, 4, and 5
the naphthenyl derivatives 4b and 8c were derived by com-
parison to its phenyl Cs symmetric analogues 4a and 8b. The
naphthenyl group is probably too bulky and cannot rotate freely,
thus leading to the C1 symmetric NMR spectra. The bisepoxide
derivatives 9 are isomers of the corresponding bisepoxides 8.
Assuming that the locations of the thiazolidinone and the two
tert-butylperoxo groups are the same as those in 4, there is no
other reasonable alternative structure for these bisepoxides. The
characteristic CdO stretching bands for the carbonyl group in
compounds 4, 8, and 9 range from 1960 to 1963 cm-1, indicating
there is no significant change in the locations of the addends.
The 1,3-dioxolane derivatives 10a to 10e showed similar NMR
patterns. Their structure should be the same as the X-ray
structure of 10d.
Mechanism Consideration. Scheme 6 shows possible path-
ways for the formation of the thiirane 3 and thiazolidinone 4.
The first step is the TMSOTf-mediated epoxide opening to give
the fullerene carbocation intermediate A. The opening is
regioselective because the other alternative X is antiaromatic
with the cation on the central cyclopentadiene pentagon.
Addition of ArNCS to cation A would form either intermediate
B or intermediate E, depending on whether N or S attacks the
cation. Loss of TMS group from B then forms the neutral
product C. Homolysis of the fullerene C-O bond forms the
relatively stable cyclopentadienyl radical intermediate D. This
is different from the Lewis acid-induced heterolytic cleavage
in the first step, where the same fullerene C-O heterolysis gave
an antiaromatic intermediate X. Recoupling of the radicals in
D with the sulfur atom finally results in the thiazolidinone 4.
The fullerene C-O bond in the intermediate F can also be
cleaved homolytically to form G in a process similar to the
formation of D. Loss of ArNCO from G forms the thiirane 3.
Table 1 shows that photolysis favored the formation of 3, and
thermal reaction in the dark favored the formation of 4. The
present mechanism cannot explain this phenomenon clearly.
Perhaps photolysis is a more efficient method than thermolysis
for the homolytic bond cleavage just like in many other organic
reactions. Two homolysis steps (F to G and G to 3) are involved
for the formation of 3, whereas only one homolysis step (C to
D) is required for the formation of 4. The phenomenon also
implies that intermediates F and C are interconvertible under
photolysis or thermolysis, the mechanism of which is probably
2522 J. Org. Chem., Vol. 73, No. 7, 2008

Fullerene Epoxide
SCHEME 7. Related Conversions in Classical Organic
Chemistry
employed in this study, the four tert-butyl peroxo groups in the
present compounds remain unchanged. Further work is in
progress to investigate the chemistry of the fullerene-mixed
peroxides in detail and to explore their applications in controlled
cage-opening reactions.
Experimental Section
All the reagents were used as received. Benzene and dichlo-
romethane used for reactions was distilled from potassium under
nitrogen; other solvents were used as received. Reactions were
carried out under lab light in air at r.t. except where indicated.
Chromatographic purifications were carried out with 200-300 mesh
silica gel. Compounds not shown below are included in the
Supporting Information. The NMR spectra were recorded at 298
K. ESI-MS spectra were recorded with CHCl3/CH3OH or CDCl3/
CH3OH as the solvent. (+) ESI-MS indicates positive mode and
(-) ESI-MS indicates negative mode.
Caution: A large amount of peroxide is involved in some of
the reactions; care must be taken to avoid possible explosion.
Preparation of Intermediates 2. To a stirred solution of the
compound 1 (132 mg, 0.12 mmol) and PhNCS (0.283 mL, 2.40
mmol) in dichloromethane (20 mL) at 30 °C was added TMSOTf
(26 µL, 0.12 mmol) in a single portion with the flask wrapped by
aluminum foil. The resulting mixture was stirred for 1 h at 30 °C,
and the reaction was quenched by adding 10 drops of 2 M HCl.
The organic layer was separated, dried with Na2SO4, filtered, and
concentrated under reduced pressure. The residue was chromato-
graphed on silica gel column eluting with toluene. The first band
was trace amount unreacted 1. The second band was 2a. The eluted
solution of 2a was evaporated and dried under atmosphere at r.t.
with the bottle wrapped with aluminum foil. Yield: 115 mg, 78%.
Compound 2b was prepared by the same procedure as 2a except
that PhNCS was replaced by 1-naphthyl isothiocyanate. Yield:
78%, 73 mg from 80 mg of compound 1.
analogous to the Dimroth rearrangement such as the second
reaction in Scheme 7.
In the case of TMSNCS reaction with 1, the thiocyanate
derivative 5 was isolated because TMS is a better leaving group
than the aryl group. The alumina-induced conversion of
compound 5 to 6 probably goes through the isomerization of 5
to the isothiocyanate intermediate H, which then forms the
oxazolidine-2-thione intermediate I. The process is similar to
the formation of 4 from intermediate B.
Transformations, analogous to the above mechanisms, have
been reported in classical organic chemistry.17 For example, a
similar intermediate was proposed in the widely accepted
mechanism for the well-established conversion of epoxide to
episulfide using ammonium thiocyanate (Scheme 7 (1)).17 The
conversion of oxazolidine-2-thione to thiazolidin-2-one is also
known in classical organic chemistry (Scheme 7 (2)).17 Such
Dimroth rearrangements usually involve ionic intermediates.
Radical intermediates D and G were proposed for the present
fullerene reactions (Scheme 6) instead of ionic species. The
cyclopentadienyl radical in the center of D and G should be
more stable than the corresponding antiaromatic cation. The
structure with a negative charge on the center pentagon of D
and G is also unlikely since this would require a positive charge
on the other group with more electronegative heteroatoms such
as oxygen.
Note: These compounds were unstable under light. Light should
be avoided throughout the experimental procedure. Its spectra
should be measured immediately.
Preparation of Compounds 3 and 4. Method A: Compound
2a (112 mg, 0.091 mmol) was dissolved in dichloromethane (12
mL). The solution was then transferred into a Dewar container,
the inside-surface of which can reflect light just like a mirror. Two
household luminescent light bulbs (12 W, commercial household
light bulb) were placed above the container. The solution was
illuminated for 90 min, the reaction was stopped and the resulting
solution was evaporated in the dark. The residue was dissolved in
4 mL benzene and chromatographed on a silica gel column eluting
with benzene. The first red band was the major product 3. Yield:
78 mg, 80%. The second red band was trace amount of 2a. After
these two bands were eluted, the solvent was changed to CH2Cl2.
The third band was compound 4a (9 mg, 8%). When the substrate
2a was changed to compound 2b, 3 and 4b were prepared by the
same procedure. Yield: 3, 74%, 40 mg from 62 mg of 2b; 4b,
15%, 9 mg from 62 mg of 2b.
Method B: The solid sample of compound 2b (85 mg, 0.067
mmol) was used just after the solution was evaporated and dried
at room temperature. The flask was wrapped with aluminum foil
and stored at r.t. for 4 days in the dark. Then the resulting solid
sample was directly chromatographed on a silica gel column eluting
with toluene. The first red band was the product 3. Yield: 17 mg,
23%. The second red band was trace amount of unreacted 2b. After
these two bands were eluted, the solvent was changed to CH2Cl2.
The third band was compound 4b (47 mg, 53%). When the substrate
2b was changed to compound 2a, 3 and 4a were prepared by the
same procedure. Yield: 3, 13%, 4 mg from 32 mg of 2a; 4a, 59%,
19 mg from 32 mg of 2a.
Conclusion
The present results show that fullerene epoxide opens into
the fullerene cation intermediate easily in the presence of a
Lewis acid such as BF3·Et2O and TMSOTf. Sulfur and oxygen
nucleophiles add to the fullerene cation to form stable sulfur-
and oxygen-bonded fullerene derivatives, respectively. Rear-
rangement processes of the fullerene-fused heterocycles exhibit
similar mechanisms with those observed for analogous organic
compounds. Fullerene epoxide has been converted into fullerene
thiirane, which exists as the 6,6-closed structure in agreement
with theoretically calculated results.11 Under the conditions
(17) (a) Sakai, S.; Niimi, H.; Kobayashi, Y.; Ishii, Y. Bull. Chem. Soc.
Jpn., 1977, 50, 3271. (b) Baba, A.; Shibata, I.; Kashiwagi, H.; Matsuda, H.
Bull. Chem. Soc. Jpn. 1986, 59, 341. (c) Robiette, R.; Dekoker-Malengreau,
A.; Marchand-Brynaert, J. Heterocycles 2003, 60, 523.
Method C: To a stirred solution of the compound 1 (100 mg,
0.092 mmol) and PhNCS (0.218 mL, 1.84 mmol) in dichlo-
J. Org. Chem, Vol. 73, No. 7, 2008 2523

Yang et al.
romethane (20 mL) at 30 °C was added TMSOTf (17 µL, 0.092
mmol) in a single portion with the flask wrapped by aluminum
foil. The resulting mixture was stirred for 1 h at 30 °C, the reaction
was quenched by adding 3 mL 2M HCl. The organic layer was
separated, dried with Na2SO4, filtered, and directly chromatographed
on a silica gel column eluting with toluene. The major band 2a
was collected in a flask wrapped with aluminum foil. The collected
solution containing 2a was refluxed for around 24 h (until 2a
disappeared as indicated by TLC). The resulting solution was
concentrated under reduced pressure. The residue was purified by
column chromatography on silica gel with benzene as eluent. The
first band was trace amount of 3, the following band was 4a (88
mg, 79%). When the PhNCS was changed to NaphthNCS, the
intermediate 2b was obtained based on the TLC analysis. However
similar procedure (refluxing for 4 days) did not give the desired
product 4b.
149.24; 149.17; 148.85; 148.79; 148.47; 148.43 (1C); 148.36;
148.27; 147.79; 147.67; 147.50; 147.25; 147.13 (3C); 145.66;
144.91 (4C); 144.73; 144.70; 144.20; 144.12; 143.85; 143.57;
143.15; 142.64; 140.85; 137.50; 113.28 (1C); 83.46 (2C-(CH3)3);
82.21 (1C, C-OH); 82.10; 82.05 (2C-(CH3)3); 81.08; 65.66 (C-
S); 26.85 (6CH3), 26.74 (6CH3), assignment was obtained from
HMBC spectrum. FT-IR (microscope): 3462; 2979; 2930; 2150;
1473; 1456; 1387; 1364; 1261; 1244; 1192; 1154; 1101; 1043; 1023;
909; 868; 732. (+) ESI-MS : m/z (rel intens) 1169 (100) [M +
NH4], 1152(86) [M + 1]; (-) ESI-MS : m/z (rel intens) 1150-
(100) [M - 1]; calculated for C77H37O9SN MW ) 1151. HRMS
C77H37O9SNNa (M + Na) calcd 1174.2081, found 1174.2060;
HRMS C77H41O9SN2 (M + NH4) calcd 1169.2527, found 1169.2511.
1
Characterization Data for Compound 6. H NMR (CDCl3,
400 MHz) δ: 7.89 (s, 1H); 1.46 (s, 18H); 1.38 (s, 18H). 13C NMR
(CDCl3, 100 MHz) all signals represent 2C except noted. δ: 170.94
(1C, CdO); 154.43; 150.58; 149.21; 149.14; 148.37; 148.28; 148.26
(1C); 148.15; 147.82; 147.63; 147.21; 147.12; 147.06 (1C); 146.75;
146.45; 145.69; 145.50; 144.98; 144.58; 144.21; 144.19; 143.70;
143.47; 143.20; 143.13; 142.80; 141.47; 138.27; 82.57; 81.98 (2C-
(CH3)3); 81.86 (2C-(CH3)3); 80.87; 68.07 (C-N); 67.05 (C-S);
26.76 (6CH3), 26.66 (6CH3). Assignment was obtained from HMBC
spectrum. FT-IR (microscope): 3392; 3268; 2979; 2930; 2870; 1709
(NHCO); 1676 (NHCO); 1473; 1456; 1387; 1364; 1260; 1243;
1193; 1134; 1104; 1039; 1020; 908; 870; 733. (+) ESI-MS : m/z
(rel intens) 1169 (100) [M + NH4]. HRMS C77H41O9SN2 (M +
NH4) calcd 1169.2527, found 1169.2523.
1
Characterization Data for Compound 3. H NMR (CDCl3,
400 MHz) δ: 1.46 (s, 18H); 1.39 (s, 18H). 13C NMR (CDCl3, 100
MHz) all signals represent 2C except noted. δ: 150.82; 149.30
(4C); 149.26; 148.74; 148.01 (1C); 147.76; 147.65; 147.60; 147.35;
147.27 (4C); 147.10; 147.06; 146.89; 146.83; 146.36; 145.74;
145.60 (1C); 145.12; 144.60; 144.39; 143.94; 143.54; 143.21;
142.78; 142.76; 141.79; 84.02; 81.82 (2C-(CH3)3); 81.63 (2C-
(CH3)3); 81.34; 57.03 (1C, C-S); 52.94 (1C, C-S); 26.79 (6CH3);
26.76 (6CH3). FT-IR (microscope): 2978; 2926; 2853; 1473; 1460;
1387; 1363; 1260; 1242; 1193; 1128; 1107; 1043; 1020; 873; 753.
(+) ESI-MS : m/z (rel intens) 1127 (100) [M + NH4]. HRMS
C76H36SO8Na (M + Na) calcd 1131.2023, found 1131.2076.
Preparation of Compound 7. To a stirred solution of compound
6 (66 mg, 0.057 mmol) and benzoyl chloride (160 µL, 1.15 mmol)
in dry dichloromethane (11 mL) at room temperature was added
anhydrous Na2CO3 (12 mg, 0.114 mmol). The resulting suspension
was refluxed for 4 h, and the reaction mixture solution was directly
chromatographed on silica gel column, eluting with dichloromethane
and petroleum ether (2:1). The first band was trace amount of
unknown compounds and unreacted PhCOCl. The second red band
was the main product 7 (17 mg, 24%). After the two bands were
eluted, the solvent was changed to CH2Cl2 and ethyl acetate (4:1).
The third band was the unreacted compound 6 (33 mg, 50%).
1
Characterization Data for Compound 4a. H NMR (CDCl3,
400 MHz) δ: 7.34-7.30 (m, 3H); 7.24 (d, 2H); 1.462 (s, 18H);
1.458 (s, 18H). 13C NMR (CS2/CDCl3, 100 MHz) all signals
represent 2C except noted. δ: 167.69 (1C); 154.93; 150.29; 148.97;
148.92; 148.08; 148.04 (1C); 147.95; 147.91; 147.70; 147.47;
146.95; 146.92; 146.90 (1C); 146.51; 145.57 (4C); 145.09; 144.57;
144.35; 144.03; 143.86; 143.53; 143.25; 143.00; 142.96; 142.64;
141.47; 138.51; 136.38 (1C, N-C in Ph); 131.27 (2C, Ph); 129.23
(2C, Ph); 129.06 (1C); 82.31; 81.55 (4C-(CH3)3); 80.68; 72.39 (C-
N); 65.15 (C-S); 26.65 (6CH3); 26.62 (6CH3). FT-IR (micro-
scope): 2978; 2932; 1692(CdO); 1593; 1492; 1477; 1454; 1387;
1364; 1334; 1308; 1242; 1193; 1157; 1115; 1103; 1041; 1019; 938;
870; 818; 752; 696; 673. Assignment was obtained from DEPT135
spectrum. (+) ESI-MS : m/z (rel intens) 1228(100) [M + 1], calcd
C83H41NO9S MW ) 1227. HRMS C83H41NO9SNa (M + Na) calcd
1250.2394, found 1250.2400; C83H42NO9S (M + H) calcd 1228.2575,
found 1228.2578.
Crystal system, space group: Monoclinic, P2(1)/c, unit cell
dimensions: a ) 23.477(5) Å, R ) 90°, b ) 13.864(3) Å, â )
111.31(3)°, c ) 19.873(4) Å, γ ) 90°, volume ) 6026(2) Å.3 Final
R indices [I > 2σ(I)], R1 ) 0.0575, wR2 ) 0.1077.
Preparation of Compounds 5 and 6. To a stirred solution of
compound 1 (40 mg, 0.037 mmol) and TMSNCS (160 µL, 1.17
mmol) in dichloromethane (5 mL) at room temperature was added
TMSOTf (16 µL, 0.074 mmol). The resulting mixture was directly
chromatographed on silica gel column after 10 min, eluting with
dichloromethane and ethyl acetate (4:1). Compound 5 was the only
band collected. The eluted solution of the product was evaporated,
washed by methanol several times to remove the TMSOH and other
impurities, and dried under atmosphere at r.t. with the bottle
wrapped with aluminum foil. Yield: 28 mg, 66%.
1
Characterization Data for Compound 7. H NMR (CDCl3,
400 MHz) δ: 8.26-8.24 (m, 2H); 7.59-7.55 (m, 3H); 1.485 (s,
18H); 1.344 (s, 18H). 13C NMR (CDCl3, 100 MHz) all signals
represent 2C except noted. δ: 170.97 (1C, CdO); 162.07 (1C, Cd
O); 154.21; 151.29; 149.21; 149.10; 148.35; 148.30 (1C); 148.26;
148.08; 147.88; 147.62; 147.32; 147.27; 146.94 (1C); 146.85;
146.10; 145.82; 145.55; 145.20; 144.52; 144.45; 143.71; 143.44;
143.41; 143.10; 142.56; 141.75; 138.11; 135.15 (1C, Ph); 131.44
(1C, Ph); 130.79 (1C, Ph); 129.95 (1C, Ph); 129.03 (1C, Ph); 126.69
(1C, Ph); 82.78; 81.95 (2C-(CH3)3); 81.68 (2C-(CH3)3); 80.95; 73.64
(C-N); 57.66 (C-S); 26.85 (6CH3), 26.65 (6CH3). FT-IR (micro-
scope): 2979; 2930; 2869; 1774; 1748; 1698; 1624; 1600; 1473;
1452; 1387; 1364; 1258; 1242; 1194; 1144; 1104; 1092; 1040; 1019;
909; 870; 733; 705. (+) ESI-MS : m/z (rel intens) 1256 (100) [M
+ 1], calcd C84H41O10SN MW ) 1255. HRMS C84H41O10SNNa
(M + Na) calcd 1278.2343, found 1278.2332; C84H41O10SNK (M
+ K) calcd 1294.2083, found 1294.2067.
Preparation of Compounds 8 and 9. To a stirred solution of
compound 4a (72 mg, 0.059 mmol) in chlorobenzene (36 mL) at
room temperature was added C60 (85 mg) under nitrogen atmo-
sphere. The resulting solution was stirred and heated for 16 h in
an oil bath at 110 °C. The resulting solution was chromatographed
on a silica gel column, eluting with toluene. The first purple band
was C60 and other unknown compounds. After the first band was
eluted, the solvent was changed to CH2Cl2. The second red band
was the unreacted 4a (23 mg, 32%). The third band was compound
9b (15 mg, 24%). The fourth band was 8b (14 mg, 22%).
Compounds 9a and 8a were prepared by the same procedure except
the reaction temperature changed to 130 °C. Yield: 9a, 22%, 18
mg from 96 mg of 6; 8a, 17%, 14 mg from 96 mg of 6). Compounds
9c and 8c were also prepared by the same procedure at 130 °C.
Compound 6 was obtained when the above the solution of
reaction mixture was directly chromatographed on 200-300 mesh
neutral Al2O3 gel column instead of silica gel, using the same eluent
(dichloromethane and ethyl acetate in 4:1 ratio). Yield: 87%, 73
mg from 80 mg of compound 1. The silica gel product 5 could
nearly quantitatively be transferred to 6 by chromatography on
neutral Al2O3 column eluting with CH2Cl2/ethyl acetate mixtures.
1
Characterization Data for Compound 5. H NMR (CDCl3,
400 MHz) δ: 5.61 (s, 1H); 1.51 (s, 18H); 1.47 (s, 18H). 13C NMR
(CDCl3, 100 MHz) all signals represent 2C except noted. δ: 155.25;
2524 J. Org. Chem., Vol. 73, No. 7, 2008

Fullerene Epoxide
TABLE 2. Yields and Conditions for the Preparation of Compounds 10 and 11
reactant
Lewis acid
solvent
CH2Cl2
time, h
0.5
product
yield (%)
p-HOC6H4CHO (5 equiv)
BF3‚Et2O (5 equiv)
10a
11
10a
11
10b
11
10b
11
10c
11
10d
11
10e
10f
10f
11
52
trace
30
16
38
29
20
trace
40
25
51
trace
51
59
48
p-HOC6H4CHO (5 equiv)
p-NO2C6H4CHO (5 equiv)
p-NO2C6H4CHO (5 equiv)
m-NO2C6H4CHO (10 equiv)
p-MeOC6H4CHO (5 equiv)
BF3‚Et2O (5 equiv)
BF3‚Et2O (5 equiv)
BF3‚Et2O (5 equiv)
BF3‚Et2O (10 equiv)
BF3‚Et2O (5 equiv)
PhH
5
PhH
3
CH2Cl2
PhH
0.5
2
CH2Cl2
9
acetaldehyde (5 equiv)
acetone (40 equiv)
BF3‚Et2O (5 equiv)
TMSOTf (1.5 equiv)
BF3‚Et2O (5 equiv)
BF3‚Et2O (5 equiv)
CH2Cl2
CH2Cl2
CH2Cl2
PhH
1
2
12
12
trace H2O in solvent
66
Yield: 9c, 19%, 15 mg from 90 mg of 4b; 8c, 23%, 18 mg from
90 mg of 4b.
Characterization Data for Compound 8a. H NMR (CDCl3,
11; Yield: 10e, 51%, 21 mg from 40 mg of 1; Yield: 10f, 59%,
25 mg from 40 mg of 1 (TMSOTf as catalyst); 10f, 48%, 20 mg
from 40 mg of 1 (BF3‚Et2O as catalyst); Yield: 11, 66%, 41 mg
from 60 mg of 1.
1
400 MHz) δ: 8.06 (broad, 1H); 1.41 (s, 18H). 13C NMR (CDCl3,
100 MHz) all signals represent 2C except noted. δ: 169.95 (1C,
CdO); 149.74; 148.63; 148.53; 148.28; 148.19; 148.01 (1C);
147.97; 147.83; 147.37 (1C); 147.34; 146.93; 146.52; 146.33;
146.02; 145.73; 145.49; 145.23; 144.71; 144.64; 144.26; 144.07;
144.03; 143.65; 143.22; 142.77; 139.36; 136.77; 83.13; 82.28 (2C-
(CH3)3); 76.50; 72.65 (C-N); 66.62; 61.36(C-S); 26.68 (6CH3).
FT-IR (microscope): 3392; 3184; 3073; 2979; 2930; 2870; 1709
(NHCO); 1680 (NHCO); 1463; 1420; 1387; 1363; 1262; 1243;
1191; 1160; 1142; 1124; 1080; 1045; 1014; 908; 899; 874; 819;
788; 759; 732. (+) ESI-MS : m/z (rel intens) 1028 (82) [M +
Na]; (-) ESI-MS : m/z (rel intens) 1004 (100) [M - 1]. HRMS
C69H19NO7SNa (M + Na) calcd 1028.0774, found 1028.0795.
Characterization Data for Compound 10d. 1H NMR (CDCl3,
400 MHz): 7.78 (d, 2H); 7.02 (d, 2H); 6.63 (s, 1H); 3.89 (s, 3H,
Me); 1.45 (s, 27H); 1.41 (s, 9H). 13C NMR (CDCl3, 100 MHz) all
signals represent 1C except noted. δ: 161.23 (1C, Ph); 151.60;
150.66; 149.17; 149.13; 149.09; 149.05; 148.96; 148.69; 148.40;
148.36; 148.23; 148.19; 148.17 (2C); 148.14; 147.82; 147.72;
147.56; 147.48; 147.32; 147.28; 147.22 (2C); 147.17; 146.88;
146.78; 146.65; 146.35; 145.68; 145.61 (2C); 145.54; 145.52;
145.49; 145.39; 145.07; 144.85; 144.51; 144.42; 144.17; 144.15;
144.04; 143.64; 143.60; 143.40; 143.36; 143.26; 143.19; 142.90;
142.71; 141.36; 141.15; 139.41; 138.58; 129.21 (2C, Ph); 127.06
(1C, Ph); 113.84 (2C, Ph); 105.72; 90.14; 84.60; 83.29; 82.95; 81.87
(2C-(CH3)3); 81.56 (1C-(CH3)3); 81.47 (2C, 1C + 1C-(CH3)3);
1
Characterization Data for Compound 9a. H NMR (CDCl3,
t
t
400 MHz) δ: 7.72 (broad, 1H); 1.49 (s, 9H); 1.41 (s, 9H). 13C
NMR (CDCl3, 100 MHz) all signals represent 1C except noted. δ:
169.38 (1C, CdO); 149.88; 149.75; 148.75; 148.61; 148.55; 148.44;
148.35; 148.15; 148.03; 147.98; 147.79; 147.74 (2C); 147.56;
147.45; 147.38; 147.29; 146.88; 146.85; 146.74; 146.60; 146.57
(2C); 146.23; 145.84; 145.76; 145.51; 145.24; 145.02; 144.94;
144.76; 144.61; 144.54 (2C); 144.46; 144.19; 144.05 (2C); 143.99;
143.72 (3C); 143.04; 142.87; 142.61; 142.45; 141.98; 141.93;
141.87; 140.15; 138.58; 137.57; 82.71; 82.36 (1C-(CH3)3); 82.14
(1C-(CH3)3); 81.15; 70.92; 70.57; 69.75; 68.73 (C-N); 68.04; 62.43
(C-S); 26.72 (3CH3); 26.65 (3CH3). FT-IR (microscope): 3387;
3193; 3081; 2979; 2930; 1711 (NHCO); 1682 (NHCO); 1455; 1421;
1387; 1363; 1262; 1244; 1191; 1142; 1093; 1039; 1021; 907; 850;
796; 758; 732. (+) ESI-MS : m/z (rel intens) 1028 (82) [M +
Na]; (-) ESI-MS : m/z (rel intens) 1004 (100) [M - 1]. HRMS
C69H18NO7S (M - 1) calcd 1004.0810, found 1004.0819.
Preparation of Compounds 10 and 11. Compound 1 was
dissolved in dry dichloromethane or benzene. The flask was
wrapped with aluminum foil and stirred at 30 °C. Then aldehyde
or acetone and BF3‚Et2O were added. Progress of the reaction was
monitored by TLC. When the 1 was nearly consumed, 2 mL of 2
M aqueous HCl was added to the mixture. The organic layer was
separated, dried with Na2SO4, and filtered. The solvent was
removed. The residue was chromatographed on a silica gel column
with dichloromethane/petroleum ether (2/1) as eluent to afford the
main product 10. The reaction time and the yield for each individual
nucleophile are listed in Table 2 (all the yields are the isolated
yields). Yield: 10a, 52%, 23 mg from 40 mg of 1; trace 11; Yield:
10a, 30%, 20 mg from 60 mg of 1; 11, 16%, 10 mg from 60 mg
of 1; Yield: 10b, 30%, 17 mg from 40 mg of 1; 11, 29%, 12 mg
from 40 mg of 1; Yield: 10b, 20%, 9 mg from 40 mg of 1; trace
11; Yield: 10c, 40%, 18 mg from 40 mg of 1; 11, 25%, 11 mg
from 40 mg of 1; Yield: 10d, 51%, 23 mg from 40 mg of 1; trace
80.71, 26.82 (3CH3 in Bu); 26.80 (3CH3 in Bu); 26.77 (3CH3 in
tBu); 26.69 (3CH3 in tBu). FT-IR (microscope): 3434; 2979; 2929;
2870; 1617; 1601; 1522; 1454; 1388; 1364; 1267; 1243; 1193; 1167;
1120; 1099; 1047; 1021; 1001; 908; 871; 836; 755; 733. (+) ESI-
MS : m/z (rel intens) 1246 (40, M + NH4), 1251(96, M + Na),
1267 (100, M + K), (-) ESI-MS: 1259 (100, M + MeO),
calculated for C84H44O11 MW ) 1228. HRMS C84H48O11N (M +
NH4) calcd 1246.3222, found 1246.3220; C84H44O11Na (M + Na)
calcd 1251.2776, found 1251.2810; C84H44O11K (M + K) calcd
1267.2515, found 1267.2514.
Crystal system, space group: monoclinic, P2(1)/c, unit cell
dimensions: a ) 23.525(5) Å, R ) 90°, b ) 14.298(3) Å, â )
93.55(3)°, c ) 18.395(4) Å, γ ) 90°, volume ) 6176(2) Å.3 Final
R indices [I > 2σ(I)], R1 ) 0.0731, wR2 ) 0.1278.
CCDC-633218 and CCDC-638148 contain the crystallographic
data for 4a and 10d, respectively. The crystallographic data can be
obtained free of charge via www.ccdc.cam.ac.uk/consts/retrieving-
.html (or from the Cambridge Crystallographic Data Centre, 12
Union Road, Cambridge CB12 1EZ, UK; fax: (+44)1223-366-
033; or e-mail: deposit@ccdc.cam.ac.uk
Characterization Data for Compound 10e. 1H NMR (CDCl3,
400 MHz) δ: 5.91 (q, 1H); 1.79 (d,3H); 1.47 (s, 9H); 1.45 (s, 9H);
1.41 (s, 9H); 1.39 (s, 9H). 13C NMR (CDCl3, 100 MHz) all signals
represent 1C except noted. δ: 151.37; 150.88; 149.20; 149.17;
149.15; 149.12; 149.05; 148.97; 148.70; 148.43; 148.24 (2C);
148.22; 148.17 (2C); 147.75; 147.64; 147.61; 147.58; 147.35;
147.33; 147.25 (2C); 147.20; 146.88; 146.83; 146.44; 146.20;
145.74; 145.60; 145.57 (4C); 145.52; 145.07; 144.83; 144.53;
144.39; 144.33; 144.10; 144.02; 143.63 (2C); 143.47; 143.39;
143.35; 143.19; 142.98; 142.68; 141.49; 141.21; 139.67; 138.34;
103.45 (CH); 90.40; 84.77; 83.22; 82.94; 81.89 (C(CH3)3); 81.83
(C(CH3)3); 81.56 (C(CH3)3); 81.53 (C(CH3)3); 80.72; 80.70; 26.82
(3CH3); 26.77 (9CH3); 18.92. FT-IR (microscope): 2978; 2922;
J. Org. Chem, Vol. 73, No. 7, 2008 2525

Yang et al.
2851; 1461; 1418; 1387; 1364; 1260; 1243; 1194; 1144; 1118; 1100;
1027; 1007; 905; 871; 755; 732. (+) ESI-MS : m/z (rel intens)
1154 (100) [M + NH4]; calculated for C78H40O10 MW ) 1136.
HRMS C78H44O10N (M + NH4) calcd 1154.2960, found 1154.2940.
Characterization Data for Compound 10f. 1H NMR (CDCl3,
400 MHz) δ: 1.94 (s, 2CH3); 1.46 (s, 18H); 1.37 (s, 18H); 13C
NMR (CDCl3, 100 MHz) all signals represent 2C except noted. δ:
151.43; 149.23; 149.12; 149.02; 148.59; 148.17(4C); 148.14;
147.60; 147.26 (5C); 147.21 (1C); 146.89; 146.31; 145.85; 145.58;
145.47; 145.16; 144.90; 144.42; 143.99; 143.55; 143.31; 143.28;
142.65; 141.28; 137.94; 116.02 (1C); 92.08; 86.03; 83.12; 81.89;
81.78 (2C(CH3)3); 81.36 (2C(CH3)3); 80.74; 27.84; 26.85 (6CH3);
26.71 (6CH3). FT-IR (microscope): 2979; 2926; 2853; 1463; 1385;
1363; 1243; 1217; 1194; 1175; 1098; 1061; 1021; 1009; 901; 873;
757 cm-1, (+) ESI-MS : m/z (rel intens) 1168 (100, M + NH4).
HRMS C79H42O10Na (M + Na) calcd 1173.2670, found 1173.2675.
noted. δ: 168.04 (1C, CdO); 148.97; 148.67 (1C); 148.64; 148.61;
148.44; 148.37; 148.09 (4C); 147.87; 147.84; 147.73; 147.71 (1C);
147.44; 145.83; 144.71; 144.67; 144.41; 143.71; 143.64; 143.59;
143.57; 142.78; 141.46; 141.06; 140.71; 139.82; 135.89; 117.25;
93.90; 85.42; 82.06 (1C, C-N); 81.55 (2C-(CH3)3); 81.41; 68.85-
(C-S); 29.41 (2CH3); 28.74 (2CH3); 26.97 (6CH3). FT-IR (mi-
croscope): 3389; 3145; 3064; 2978; 2934; 2868; 1700 (NHCO);
1677 (NHCO); 1455; 1384; 1366; 1262; 1241; 1221; 1191; 1175;
1150; 1120; 1077; 1061; 1034; 1007; 934; 908; 891; 821; 761;
733. (+) ESI-MS : m/z (rel intens) 1145 (100) [M + Na], 1122
(52) [M + 1]; (-) ESI-MS : m/z (rel intens) 1120 (100) [M - H],
1152 (26) [M + CH3O]. HRMS C72H24NO8S (M - CH3COCH3
- 1) calcd 1062.1228, found 1062.1222; C69H18NO7S (M - 2 CH3-
COCH3 - 1) calcd 1004.0810, found 1004.0815.
Characterization Data for Compound 13a. 1H NMR (CDCl3,
400 MHz) δ: 6.99 (broad, 1H); 1.86 (s, 3H); 1.83 (s,3H); 1.50 (s,
3H); 1.43 (s, 3H); 1.42 (s, 9H); 1.38 (s, 9H). 13C NMR (CDCl3,
100 MHz) all signals represent 1C except noted. δ: 169.79 (1C,
CdO); 150.34; 149.95; 149.76; 149.37; 148.66; 148.54 (3C); 148.41
(2C); 148.38; 148.35; 148.33; 148.25 (3C); 148.21; 148.02; 147.90;
147.81; 147.79; 147.72; 147.67 (2C); 147.65; 147.47; 147.06;
146.86; 146.06; 146.02; 145.76; 145.41; 145.33; 144.87; 144.84;
144.82 (2C); 144.77; 144.64; 144.51; 144.45; 144.41; 144.38;
144.09 (2C); 143.88; 143.79 (3C); 143.64; 143.60; 143.42; 143.33;
142.29; 116.16; 116.10; 89.08; 88.85; 82.11 (1C-(CH3)3); 81.89
(1C-(CH3)3); 81.17; 78.07; 67.76; 65.88; 28.26 (CH3); 27.87 (CH3);
26.85 (3CH3); 26.76 (CH3); 26.69 (4CH3). FT-IR (microscope):
3388; 3182; 3070; 2979; 2929; 2868; 1709 (NHCO); 1677 (NHCO);
1454; 1421; 1385; 1365; 1243; 1219; 1192; 1141; 1112; 1080; 1021;
908; 882; 869; 850; 797; 758; 733. (+) ESI-MS : m/z (rel intens)
1086 (100) [M - CH3COCH3 + Na]; (-) ESI-MS: m/z (rel intens)
1062 (100) [M - CH3COCH3 - 1], 1004 (32) [M - 2 CH3COCH3
- 1]; calculated for C75H31NO9S MW ) 1121. HRMS C72H26-
NO8S (M - CH3COCH3 + 1) calcd 1064.1374, found 1064.1359;
C72H25NO8SNa (M -CH3COCH3 + Na) calcd 1086.1193, found
1086.1155.
1
Characterization Data for Compound 11. H NMR (CDCl3,
400 MHz): 4.27 (s, 1H in OH); 1.47 (s, 18H); 1.42 (s, 18H). 13C
NMR (CDCl3, 100 MHz) all signals represent 2C except noted. δ:
151.16; 149.57; 149.13; 149.12; 148.62; 148.34 (3C); 148.16;
148.09; 147.56; 147.30 (3C); 147.26; 146.92; 145.88; 145.63;
145.19; 145.14; 145.04; 144.83; 144.46; 144.20; 143.81; 143.47;
143.23; 142.94; 141.15; 139.47; 89.87; 83.51; 82.37; 82.14 (2C-
(CH3)3); 81.97 (2C-(CH3)3); 80.80; 26.72 (6CH3); 26.70 (6CH3).
FT-IR (microscope): 3453; 2980; 2931; 2871; 1529; 1467; 1387;
1364; 1306; 1262; 1243; 1230; 1193; 1121; 1106; 1092; 1058; 1023;
1006; 979; 896; 871; 755; 728; 695. (-) ESI-MS : m/z (rel intens)
1181 (100) [M - OH + 2 OCH3], (+) ESI-MS : m/z (rel intens)
1168 (100) [M - OH + OCH3+ NH4]. HRMS C76H37O11BNa (M
+ Na) calcd 1159.2326, found 1159.2354.
Preparation of Compounds 12 and 13. To a stirred solution
of compound 8b (28 mg, 0.026 mmol) and acetone (76 µL, 1.04
mmol) in dry dichloromethane (10 mL) at 30 °C was added
TMSOTf (18 µL, 0.104 mmol). The flask was wrapped with
aluminum foil and stirred. The color of the solution slowly changed
from light red to dark red. After being stirred for 30 min, 2 mL of
2 M aqueous HCl was added to the mixture. The organic layer
was separated, dried with Na2SO4, and filtered. The solvent was
removed. The residue was chromatographed on a silica gel column
with dichloromethane as eluent to afford the main product 12b (10
mg, yield: 32%). Compounds 12a, 13a, and 13b were prepared
by the same procedure. Yield: 12a, 67%, 12 mg from 16 mg of
8a; 13a, 45%, 11 mg from 22 mg of 9a; 13b, 45%, 14 mg from 28
mg of 9b.
Acknowledgment. Financial support is provided by NNSFC
(Grants 20632010, 20521202, and 20772004) and the Major
State Basic Research Development Program (2006CB806201).
Supporting Information Available: Characterization data for
compounds not listed in the experimental section, selected NMR,
MS, IR spectra, and crystallographic data for 4a and 10d. The
material is available free of charge via the Internet at http://
pubs.acs.org.
Characterization Data for Compound 12a. 1H NMR (CDCl3,
400 MHz) δ: 7.40 (broad, 1H); 1.99 (s, 6H); 1.98(s, 6H); 1.31 (s,
18H). 13C NMR (CDCl3, 100 MHz) all signals represent 2C except
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2526 J. Org. Chem., Vol. 73, No. 7, 2008