Synthesis of new phosphorylated fullerene C60 derivatives soluble in polar solvents

Article abstract of DOI:10.1007/s11172-014-0607-6

A directed synthesis of new phosphorylated methanofullerenes containing acetonide fragments was accomplished for the first time, their chemical structure was confirmed by a combination of spectroscopic methods. Removal of the acetonide protection produced new phosphorrylated diol methanofullerenes, their structure and properties were studied. The diol methanofullerenes are well soluble in polar solvents, including a mixture of DMSO-water (1: 9).

Full text of DOI:10.1007/s11172-014-0607-6

Russian Chemical Bulletin, International Edition, Vol. 63, No. 6, pp. 1386—1389, June, 2014
1386
Synthesis of new phosphorylated fullerene C60 derivatives soluble
in polar solvents*
V. P. Gubskaya, G. M. Fazleeva, A. A. Gil´mutdinova, Sh. K. Latypov, D. R. Sharafutdinova,
I. A. Nuretdinov, and O. G. Sinyashin
A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan Scientific Center of the Russian Academy of Sciences,
8 ul. Akad. Arbuzova, 420088 Kazan, Russian Federation.
Fax: +7 (843 2) 75 2253. Eꢀmail: in@ iopc.ru
A directed synthesis of new phosphorylated methanofullerenes containing acetonide fragꢀ
ments was accomplished for the first time, their chemical structure was confirmed by a combiꢀ
nation of spectroscopic methods. Removal of the acetonide protection produced new phosphoꢀ
rylated diol methanofullerenes, their structure and properties were studied. The diol methanoꢀ
fullerenes are well soluble in polar solvents, including a mixture of DMSO—water (1 : 9).
Key words: phosphorylated methanofullerenes, acetonide protection, methods of NMR 2D
homoꢀ and heterocorrelation.
Development of new efficient approaches to the funcꢀ
tionalization of fullerenes with different organic comꢀ
pounds is an important direction in chemistry of fullerenes.
Such approaches should provide high yields of the target
products and ready addition of required functional groups
to the external surface of the carbon cage. The major efforts
of chemists are directed on the preparation of various waꢀ
terꢀsoluble fullerene derivatives. By now, a number of
fullerene C60 derivatives were synthesized which possess
satisfactory solubility in polar solvents and confirm that
fullerenes exhibit a wide range of noticeable biological
activity, including antiviral (toward various strains of inꢀ
fluenza virus) and photodynamic activity (on treatment of
human cancer diseases).1—6
For the preparation of waterꢀsoluble fullerene C60 derivꢀ
atives, it is necessary to introduce hydroxy groups in the
molecule. It is known that hydroxy groups can be protected
by acetonide (isopropylidene) protection, which afterwards
can be removed under mild conditions. Functionalization of
fullerene molecule with two or more acetonide groups with
subsequent removal of the protection and formation of polyꢀ
ols can lead to compounds soluble in polar and aqueous media.
The purpose of the present studies is the synthesis of
new phosphorylated fullerene derivatives soluble in polar
solvents, including water.
enesulfonic acid led to acetonide derivatives 1 and 2, having
spectral characteristics that agree with the literature data.7
Compounds 1 and 2 were converted to phosphorylated
derivatives containing acetonide fragments. The reaction
of 1 with chloroacetyl chloride in the presence of triethylꢀ
amine in benzene gave the corresponding chloroacetate 3,
the reaction of which with triisopropyl phosphite led to
phosphone acetate 4 (Scheme 1). New methanofullerene 5
was synthesized by the reaction of 4 with fullerene C60
(the Bingel—Hirsch reaction).8—9 According to the same
scheme, the corresponding phosphone acetate 7 was obꢀ
tained from acetonide 2 through 4ꢀchloroacetoxymethylꢀ
2,2ꢀdimethylꢀ1,3ꢀdioxolane (6), the reaction of which with
fullerene C60 gave phosphorylated methanofullerene 8
(Scheme 2).
The structures of compounds were confirmed by specꢀ
troscopic data, their composition by mass spectroscopy
MALDIꢀTOF. The mass spectra of compounds 5 and 8
exhibit peaks of molecular ions [M]+ with m/z 1098.40
and 1056.7, respectively, that confirms the composition of
the molecules under study.
Results and Discussion
UV spectra of methanofullerenes 5 and 8 exhibit abꢀ
sorption maxima at 256, 328, 429, 490, and 696 nm. The
peak with low intensity at 429 nm is characteristic of all
the [6,6]ꢀclosed adducts of fullerene C60.
The reaction of hexaneꢀ1,2,6ꢀtriol and propaneꢀ1,2,3ꢀ
triol in refluxing acetone with a catalytic amount of pꢀtoluꢀ
The structures of fullerene C60 derivatives 5 and 8 were
confirmed by NMR 1Dꢀ and 2Dꢀcorrelation methods.
* Dedicated to Academician of the Russian Academy of Sciences
O. N. Chupakhin on the occasion of his 80th birthday.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1386—1389, June, 2014.
1066ꢀ5285/14/6306ꢀ1386 © 2014 Springer Science+Business Media, Inc.

New phosphorylated methanofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 6, June, 2014
1387
Scheme 1
1
The lines in the H and 13C NMR spectra of these comꢀ
Scheme 2
pounds were assigned based on the 1H—1H COSY, 1H—13C
HSQC, and 1H—31P HMBC experiments, which alꢀ
lowed us to establish the addend structure beginning from
the methyl group of the acetonide fragment and the
P(O)(PriO)2 group to the carbon atom C(61). The presꢀ
ence of the bond between these fragments is also inferred
1
from the presence of the correlation in the 2D H—31P
HMBC spectrum between the proton of the ester group
(OCH2) and the phosphorus atom, as well as the presence
of the direct spinꢀspin coupling constant 1JCP = 165.2 Hz
between the atom C(61) and the phosphorus atom (Fig. 1).
Analysis of the 13C NMR spectra allowed us to draw a final
conclusion on the structure of methanofullerenes 5 and 8.
Besides signals of the addend, the 13C NMR spectra of
compounds 5 and 8 exhibit resonances in the region charꢀ
acteristic of the sp2ꢀhybridized carbon atoms of fulꢀ
lerene ( 136—148) and the sp3ꢀhybridized carbon atoms
C(1)/C(6) ( = 70.8, 3JCP = 3.2 Hz). The presence of the
spinꢀspin coupling constants between the phosphorus atom
with the carbon atoms C(1)/C(6) of the fullerene sphere,
as well as the chemical shift values indicate the cycloaddiꢀ
tion at the 6ꢀ6ꢀclosed bond of the fullerene sphere.
Fig. 1. 1H NMR spectra in CDCl3 and principal heteronuclear
HMBC correlations (shown with solid (1H—13C) and dashed
(1H—31P) arrows) for compound 5.
Acetonide protection in compounds 5 and 8 was easily
removed upon treatment with hydrochloric acid (Scheme 3).

1388
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 6, June, 2014
Gubskaya et al.
MALDI mass spectra were recorded on an ULTRAFLEX
III TOF/TOF mass spectrometer (Bruker Daltonik GmbH, Breꢀ
men, Germany) in the linear mode. pꢀNitroaniline was used as
a matrix. Mass spectra, besides the protonated molecular ions
[MH]+, often exhibited the [MNa]+ and [MK]+ ions.
The yields of diol methanofullerenes 9 and 10 were virtuꢀ
ally quantitative (93 and 90%, respectively).
Scheme 3
4ꢀ(2,2ꢀDimethylꢀ1,3ꢀdioxolanꢀ4ꢀyl)butanol (1). A solution of
hexaneꢀ1,2,6ꢀtriol (22.2 g, 0.17 mol) with a catalytic amount of
pꢀtoluenesulfonic acid in distilled acetone (100 mL) was refluxed
for 7 h. Then, the reaction mixture was cool and allowed to stand
for 12 h over the freshly calcined potash. After filtration, the
reaction mixture was concentrated in vacuo, using a waterꢀjet
pump. The residue was distilled at 109—110 C (1 Torr) to obꢀ
tain compound 1 (19.5 g, 67.7%). IR (neat), /cm–1: 514, 647,
739, 791, 856, 893, 1058, 1157, 1216, 1248, 1325, 1370, 1435,
1
1457, 3424. H NMR, : 1.35 (s, 3 H, Me); 1.40 (s, 3 H, Me);
1.50—1.65 (m, 6 H, CH2); 3.51 (t, 1 H, CH, J = 7.3 Hz), 3.65
(q, 2 H, OCH2, J =6.4 Hz), 4.02—4.09 (m, 2 H, CH2).
(2,2ꢀDimethylꢀ1,3ꢀdioxolanꢀ4ꢀyl)methanol (2). Compound 2
was obtained similarly to 1. The residue was distilled at 54—55 C
(1 Torr), resulting in compound 2 (12.4 g, 38.8%). IR (neat),
/cm–1: 516, 567, 653, 792, 844, 970, 1052, 1074, 1119, 1157,
1
1214, 1256, 1372, 1457, 3458. H NMR, : 1.33 (s, 3 H, Me);
1.40 (s, 3 H, Me); 2.46 (br.s, 1 H, OH); 3.57—3.75 (m, 3 H,
CH2, 1 H, OCH2); 3.99 (t, 1 H, OCH2, J = 7.3 Hz); 4.19 (q, 1 H,
CH, J = 6.4 Hz).
4ꢀ(2,2ꢀDimethylꢀ1,3ꢀdioxolanꢀ4ꢀyl)butyl chloroacetate (3).
Chloroacetyl chloride (5.5 g, 0.048 mol) was added dropwise to
a solution of 4ꢀ(2,2ꢀdimethylꢀ1,3ꢀdioxolanꢀ4ꢀyl)ꢀ1ꢀbutanol
(7.8 g, 0.048 mol) and triethylamine (4.9 g, 0.048 mol) in anꢀ
hydrous benzene (50 mL) at 5 C in the flow of argon and conꢀ
tinuous stirring. After 12 h, a precipitate of Et3N•HCl was filꢀ
tered off, the filtrate was concentrated. The fractional distillaꢀ
tion in vacuo gave the pure product 3 (7.6 g, 66%), b.p. 100—104
(0.1 Torr), nD20 = 1.4560. IR (neat), /cm–1: 471, 518, 698, 739,
786, 858, 1059, 1187, 1255, 1311, 1377, 1416, 1511, 1461, 1648,
1749 (C=O), 2869, 2938. 1H NMR, : 1.31 (s, 3 H, Me); 1.37 (s, 3 H,
Me); 1.49—1.70 (m, 6 H, CH2); 3.40 (t, 2 H, CH2, J = 7 Hz);
3.98—4.05 (m, 3 H, CH, OCH2); 4.10 (t, 2 H, CH2, J = 6.6 Hz).
Found (%): C, 52.59; H, 7.58; Cl, 14.32. C11H19O4Cl. Calculatꢀ
ed (%): C, 52.70; H, 7.64; Cl, 14.14.
Diisopropyl 4ꢀ[(2,2ꢀdimethylꢀ1,3ꢀdioxolanꢀ4ꢀyl)butoxycarbꢀ
onyl]methylphosphonate (4). Chloroacetate 3 (5 g, 0.02 mol) was
added to triisopropyl phosphite (4.15 g, 0.02 mol) at 100—110 C.
The reaction mixture was heated to 150 C for 0.5 h. The organic
layer was decanted. The filtrate was concentrated in vacuo of
a waterꢀjet pump. The product 4 was isolated by column chroꢀ
matography on silica gel (eluent: hexane—ethyl acetate (5 : 1))
as a dense light oil with Rf = 0.59, the yield was 5.2 g (68.4%).
MS: [MH]+ 381.19; [MNa]+ 402.79; [MK]+ 419.38 C17H33PO7
Calculated: M = 380.42. IR (neat), /cm–1: 514, 552, 579, 609,
638, 671, 705, 738, 789, 812, 854, 995, 1057, 1096, 1156, 1184,
1206, 1232, 1266, 1369, 1427, 1454, 1538, 1639, 1742, 2327.
1H NMR, : 1.33 (s, 3 H, Me); 1.38 (s, 3 H, Me); 1.53 (s, 3 H, Me);
1.54 (s, 3 H, Me); 1.58 (s, 2 H, CH2); 1.59 (s, 2 H, CH2); 1.84
(m, 2 H, CH2); 3.48 (t, 1 H, CH2, J = 7.2 Hz), 4.02 (m, 1 H,
CH, 1 H, CH2); 4.45 (t, 2 H, OCH2, J = 6.6 Hz); 5.1—5.14
(m, 2 H, OCH). 31P NMR, : 17.69.
The studies of solubility of obtained compounds 9 and
10 in polar solvents, including water, showed that they are
well soluble in methyl and ethyl alcohols, chloroform,
DMSO, as well as in the mixture DMSO—water (1 : 9),
but are insoluble in water with different pH values (5—9).
Experimental
HPLC analysis was carried out on an Agilent Technologies
1200 Series chromatograph with a UV detector, using a column
with a C18 reversed phase (Partisilꢀ5 ODSꢀ3), eluent toluene/
CH3CN (1 : 1, v/v). Organic solvents were dried and distilled.
Fullerene C60 (99.9% purity) used in the work was produced in
the FullereneꢀCenter, Nizhny Novgorod. All chemical manipuꢀ
lations were carried out under dry argon.
UV spectra were recorded on a Specord Mꢀ40 spectrophotoꢀ
meter in dichloromethane, IR spectra were recorded on a Brukꢀ
erꢀVector 22 Fourierꢀtransform spectrometer (KBr pellets).
NMR spectra were recorded on a Bruker Avanceꢀ600 spectroꢀ
meter (600 MHz (1H) and 150.926 MHz (13C)) at 30 C in
CDCl3, using residual signal of CHCl3 ( 7.26) and the signal
61ꢀDi(isopropoxyphosphorylꢀ61ꢀ[4ꢀ(2,2ꢀdimethylꢀ1,3ꢀdiꢀ
oxolanꢀ4ꢀylbutyl)oxycarbonyl]methano[60]fullerene (5). The reꢀ
agents CBr4 (0.208 g, 0.63 mmol), phosphonate 4 (0.24 g,
0.63 mmol), and DBU (0.095 g, 0.63 mmol) were sequentially
added to a solution of fullerene C60 (0.3 g, 0.45 mmol) in toluene
H
of CDCl3 (C 77.0) as internal references. The structures of comꢀ
pounds were established based on the 1Dꢀ and 2Dꢀcorrelation
NMR experiments (DEPT, 1H—1H COSY, 1H—13C HSQC,
1H—13C HMBC, and 1H—31P HMBC).

New phosphorylated methanofullerenes
Russ.Chem.Bull., Int.Ed., Vol. 63, No. 6, June, 2014
1389
(200 mL) with stirring under argon at room temperature. After
12 h, the reaction mixture was washed with water (2×20 mL) and
concentrated. Column chromatography on SiO2 was used to isoꢀ
late the unreacted fullerene C60, (0.101 g) (eluent toluene—hexꢀ
ane, 1 : 1) and compound 5 (0.0998 g) (eluent toluene—acetoniꢀ
trile, 40 : 1) in 32.9% yield calculated on the reacted fullerene.
UV (CH2Cl2), max/min: 327, 430, 492, 696. MS: [M]+ 1098.40.
C77H31O7P. Calculated: M = 1099.06. IR (KBr), /cm–1: 526, 572,
653, 707, 731, 758, 800, 853, 889, 986, 1037, 1098, 1177, 1224, 1264,
1372, 1426, 1453, 1537, 1644, 1733, 2860, 2927, 2975, 3442.
1H NMR (CDCl3), : 1.39 (s, 3 H, Me); 1.44 (s, 3 H, Me);
1.58—1.60 (d, 3 H, Me); 1.64—1.66 (d, 3 H, Me), 1.91 (t, 2 H, CH2,
J = 6.8 Hz); 3.53 (t, 2 H, CH2, J = 6.7 Hz); 4.04—4.10 (m, 3 H,
CH—CH2); 4.51 (t, 2 H, OCH2, J = 6.4 Hz); 5.16—5.21 (m, 2 H,
OCH). 31P NMR, : 9.08. 13C NMR, : 22.41, 25.75, 27.01,
28.63, 33.20, 50.06 (J = 165.2 Hz), 67.14, 69.41, 70.63, 73.88,
108.73, 136.88, 140.80, 141.10, 141.82, 142.01, 142.19, 142.22,
142.65, 142.94, 143.06, 143.18, 143.80, 143.94, 144.54, 144.61,
144.69, 144.80, 144.95, 145.09, 145.23, 145.39, 164.23 (C=O).
(2,2ꢀDimethylꢀ1,3ꢀdioxolanꢀ4ꢀylmethyl) chloroacetate (6).
The product 6 was obtained similarly to compound 3, the yield was
1058.47. C74H27O7P. Calculated: M = 1058.15. IR (KBr), /cm–1
:
525, 575, 752, 996, 1096, 1177, 1228 (P=O), 1374, 1426, 1538,
1652, 1734 (C=O), 2078, 2187, 2272, 2860, 2926, 2974, 3413
(OH). 1H NMR, : 1.46—1.52 (dd,, 12 H, Me); 1.72—1.73 (br.d,
4 H, CH2); 3.22 (t, 1 H, CH, J = 6.3 Hz); 3.33 (br.s, 2 H, CH2);
4.41 (t, 2 H, CH2, J = 6.1 Hz); 5.00—5.06 (m, 4 H, OCH2).
31P NMR, : 8.66. 13C NMR, : 22.15, 24.09, 24.26, 28.76,
33.32, 50.17, 51.25, 66.38, 67.58, 71.43, 74.14, 74.18, 79.59,
136.82, 140.71, 140.88, 141.09, 141.43, 142.01, 142.09, 142.65,
142.89, 143.08, 143.76, 143.91, 144.48, 144.52, 144.67, 144.77,
145.03, 145.18, 145.28, 145.53, 148.15, 163.98 (C=O).
61ꢀDi(isopropoxy)phosphorylꢀ61ꢀ[(2,3ꢀdihydroxypropoxy)ꢀ
carbonyl]methano[60]fullerene (10). Compound 10 was obtained
similarly to compound 9 in 90% yield. MS (MALDI): [MH]+
1016.94. C71H21O7P. Calculated: M = 1016.91. IR (KBr),
/cm–1: 526, 576, 755, 896, 1000, 1096, 1177, 1228 (P=O), 1243,
1264, 1316, 1427, 1540, 1636, 1738 (C=O), 2328, 2974, 3421
(OH). 1H NMR, : 1.56, 1.65 (both d, 6 H each, Me); 3.22—3.33
(br.m, 2 H, CH2); 4.29 (br.s, 1 H, CH); 4.61 (m, 2 H, OCH2);
5.13—5.20 (br.m, 2 H, OCH). 31P NMR, : 11.25. 13C NMR,
: 24.09, 49.57, 63.01, 68.38, 69.58, 71.43, 75.18, 79.59, 138.82,
140.71, 140.88, 141.09, 141.43, 142.01, 142.09, 142.65, 142.89,
143.08, 143.76, 143.91, 144.01, 144.48, 144.52, 144.67, 144.77,
145.03, 145.18, 145.28, 145.53, 148.15, 164.98 (C=O).
62.7%, nD20 = 1.4520, b.p. 87—90 (0.1 Torr). IR (KBr), /cm–1
:
472, 517, 597, 792, 843, 925, 1053, 1157, 1215, 1255, 1316,
1377, 1416, 1457, 1512, 1649, 1751, 2934, 2988. 1H NMR,
: 1.38 (s, 3 H, Me); 1.45 (s, 3 H, Me); 3.76—3.80 (m, 2 H, CH2);
4.09—4.13 (m, 2 H, OCH2); 4.19—4.37 (m, 3 H, CH—CH2).
Found (%): C, 46.19; H, 6.18; Cl, 17.01. C8H13O4Cl. Calculatꢀ
ed (%): C, 46.05; H, 6.28; Cl, 16.99.
This work was financially supported by the Russian
Academy of Sciences (Program for Basic Research 24P of
the Presidium of RAS) and the Russian Foundation for
Basic Research (Project No. 12ꢀ03ꢀ97084 rꢀpovolzh´eꢀa), the
Ministry of Education and Science of the Russian Federation
(State Contract Nos 02.451.11.7036 and 02.451.11.7019).
The structures of compounds were studied in the NMR
Department of the Federal Multiꢀuser spectroanalytical
center of physicochemical studies of structure, composiꢀ
tion, and properties of compounds and materials (FMUC
SAC) and Federal Multiꢀuser center of physicochemical
studies of compounds and materials (FMUC PCS).
Diisopropyl (2,2ꢀdimethylꢀ1,3ꢀdioxolanꢀ4ꢀylmethoxycarbonꢀ
ylmethyl)phosphonate (7). Compound 7 (a dense light oil), Rf = 0.52
was obtained from chloroacetate 6 under the same condition as
compound 4, the yield was 59.7% (1.7 g). IR (neat), /cm–1
:
514, 613, 720, 765, 838, 889, 938, 989, 989, 1055, 1104, 1143,
1179, 1216, 1261, 1375, 1456, 1742, 2936, 2982. 1H NMR, :
1.37, 1.46, 1.54, 1.58 (all s, 3 H each, CH3); 3.78—3.91 (q, 2 H,
CH2, J = 6.3 Hz); 4.11—4.15 (q, 1 H, CH, J = 5.7 Hz); 4.39—4.53
(m, 2 H, OCH2); 5.11—5.14 (m, 2 H, OCH). 31P NMR, : 17.27.
Found (%): C, 55.21; H, 7.79; P, 9.01. C16H27O6P. Calculated (%):
C, 55.48; H, 7.86; P, 8.94.
61ꢀDi(isopropoxyphosphorylꢀ61ꢀ(2,2ꢀdimethylꢀ1,3ꢀdioxolanꢀ
4ꢀylmethoxycarbonyl)methano[60]fullerene (8). Methanofullerꢀ
ene 8 was obtained under conditions of the Bingel—Hirsch reacꢀ
tion similarly to compound 5 in 38.4% yield (0.107 g) calculated
on the reacted fullerene. MS: [MH]+ 1056.70. C74H25O7P. Calꢀ
culated: M = 1056.13. UV (CH2Cl2), max/nm: 328, 429, 489, 696.
IR (KBr), /cm–1): 529, 577, 647, 749, 838, 997, 1034, 1178,
1252, 1373, 1426, 1452, 1635, 1680, 1741, 2979. 1H NMR,
: 1.37, 1.46, 1.54, 1.58 (all s, 3 H each, Me); 3.78—3.91 (q, 2 H,
CH2, J = 6.8 Hz); 4.11—4.15 (m, 1 H, CH); 4.39—4.53 (m, 2 H,
OCH2); 5.11—5.14 (m, 2 H, OCH). 31P NMR, : 9.51. 13C NMR,
: 24.07, 24.32, 25.41, 26.96, 49.06, 66.73, 67.09, 73.08, 73.98,
74.05, 109.95, 136.88, 140.86, 141.06, 141.86, 142.04, 142.07,
142.19, 142.21, 142.72, 142.99, 143.12, 143.19, 143.84, 144.01,
144.56, 144.63, 144.67, 144.74, 144.93, 144.99, 145.07, 145.14,
145.28, 147.60, 147.64, 147.67, 164.08.
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61ꢀDi(isopropoxy)phosphorylꢀ61ꢀ[(5,6ꢀdihydroxyhexyloxy)ꢀ
carbonyl]methano[60]fullerene (9). Hydrochloric acid (0.001 mL,
0.273 mmol) was added to compound 5 (0.030 g, 0.273 mmol) in
toluene (10 mL). The reaction mixture was allowed to stand in
a dark place for 24 h. The solution in toluene became colorless,
a precipitate was formed in the flask, which was filtered off and
washed with toluene. The yield was 93% (0.027 g). MS: [MH]+
Received March 31, 2014:
in revised form May 6, 2014