Synthesis of [60]fullerene-glycopyranosylaminopyrimidin-4-one conjugates

Article abstract of DOI:10.1016/j.tet.2008.02.057

The synthesis of several C₆₀ derivatives containing a 6-(β-d-glycopyranosylamino)pyrimidin-4-one unit and a C₆₀-uridine conjugate is described. The fullerene derivatives bearing a 4-(β-d-glycopyranosylamino)pyrimidin-4-one moiety were synthesised by 1,3-dipolar cycloaddition reactions of C₆₀ with azomethine ylides generated in situ from the corresponding 5-formylpyrimidin-4-one derivatives and N-methylglycine. The synthesis of the C₆₀-uridine conjugate involved the selective protection of the 2′- and 3′-hydroxyl groups of uridine, esterification, cyclopropanation of C₆₀ and, finally, the deprotection of the hydroxyl groups. One of the fullerene-glycopyranosylaminopyrimidin-4-one conjugates was characterised by single-crystal X-ray crystallography. Differentiation between pairs of diastereoisomers, for several fullerene derivatives, was achieved through the study of their gas-phase fragmentations.

Full text of DOI:10.1016/j.tet.2008.02.057

Available online at www.sciencedirect.com
Tetrahedron 64 (2008) 4427e4437
www.elsevier.com/locate/tet
Synthesis of [60]fullereneeglycopyranosylaminopyrimidin-4-one
conjugates
a
a
a
a,
Carina I.C. Jord ~a o , Andreia S.F. Farinha , Roger F. Enes , Augusto C. Tom e´ *,
a
a
a
a
Artur M.S. Silva , Jos e´ A.S. Cavaleiro , Catarina I.V. Ramos , M.G. Santana-Marques ,
b
c
c
Filipe A. Almeida Paz , Jos e´ M. de la Torre Ramirez , Maria D.L. de la Torre ,
c,
Manuel Nogueras *
a
Departamento de Qu ´ı mica, Universidade de Aveiro, 3810-193 Aveiro, Portugal
b
Departamento de Qu ´ı mica, CICECO, Universidade de Aveiro, 3810-193 Aveiro, Portugal
c
Departamento de Qu ´ı mica, Inorg a´ nica y Org a´ nica, Facultad de Ciencias Experimentales, Universidad de Ja e´ n, 23071 Ja e´ n, Spain
Received 7 January 2008; received in revised form 12 February 2008; accepted 16 February 2008
Available online 21 February 2008
Abstract
The synthesis of several C60 derivatives containing a 6-(b-D-glycopyranosylamino)pyrimidin-4-one unit and a C60euridine conjugate is
described. The fullerene derivatives bearing a 4-(b-D-glycopyranosylamino)pyrimidin-4-one moiety were synthesised by 1,3-dipolar cycloaddi-
tion reactions of C60 with azomethine ylides generated in situ from the corresponding 5-formylpyrimidin-4-one derivatives and N-methylglycine.
0
0
The synthesis of the C60euridine conjugate involved the selective protection of the 2 - and 3 -hydroxyl groups of uridine, esterification, cyclo-
propanation of C60 and, finally, the deprotection of the hydroxyl groups. One of the fullereneeglycopyranosylaminopyrimidin-4-one conjugates
was characterised by single-crystal X-ray crystallography. Differentiation between pairs of diastereoisomers, for several fullerene derivatives,
was achieved through the study of their gas-phase fragmentations.
Ó 2008 Elsevier Ltd. All rights reserved.
Keywords: Fullerene derivatives; Nucleosides; X-ray crystallography; Mass spectrometry
4
potential biological activity, we decided to prepare a series of
1
. Introduction
fulleropyrrolidineeglycopyranosylaminopyrimidin-4-one con-
jugates and a C euridine conjugate. 6-(b-D-Glycopyranosyl-
amino)pyrimidin-4-ones, such as compounds 1e6, are potential
Since the beginning of the large-scale production of C60 in
990, a wide variety of C60 derivatives have been synthesised.
60
1
1
5
biologically active compounds. They can be considered as
Many of them exhibit interesting electronic properties or bio-
logical activities. These compounds have potential biomedical
application such as HIV-1 protease inhibitors, neuroprotective
agents, photosensitisers for photodynamic therapy, X-ray and
nucleoside analogues where the anomeric carbon of the carbo-
hydrate is bonded to the 6-amino group and not to a pyrimidine
nitrogen atom.
2
MRI contrast agents, etc. The search for new biologically active
Reports on the synthesis of C enucleoside conjugates are
6
0
3
fullerene derivatives is still a rewarding challenge. Following
our interest in the synthesis of fullerene derivatives with
6,7
scarce but two examples have been published recently. In
0
one case, nitrogen-bridged [60]fullerenee3 -deoxythymidine
0
0
conjugates were prepared from the reaction of 3 -azido-3 -de-
6
oxythymidine (AZT) with C . Other studies involved the
6
0
synthesis of a C eguanosine conjugate, which was used to
0
build porphyrinefullerene and phthalocyanineefullerene
dyads assembled through WatsoneCrick hydrogen bonds.
6
*
Corresponding authors. Tel.: þ351 234 370 712; fax: þ351 234 370 084.
E-mail addresses: actome@ua.pt (A.C. Tom e´ ), mmontiel@ujaen.es
M. Nogueras).
7
a
7b
(
0040-4020/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2008.02.057

4428
C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
In this study, we took advantage of the presence of a formyl
Table 1
Yields of the fulleropyrrolidine derivatives 7e12 and the monoisotopic masses
group in the glycopyranosylaminopyrimidin-4-one derivatives
to generate azomethine ylides, which were trapped with C60
yielding the corresponding fulleropyrrolidine derivatives.
þ
of the corresponding [MþH] ions
1
2
þ
Compound
X
R
R
Yield Diastereoisomers [MþH]
(
%)
ratio (a/b)
ions (Da)
1
2
3
4
5
6
7
S
Me
Me
H
H
38
24
2:3
4:5
5:6
2:3
2:3
3:2
1205
1189
1261
1277
1263
1191
2
. Results and discussion
8
O
O
S
9
Me CH
Me CH
2
2
2
OAc 25
OAc 31
OAc 35
27
2
.1. Fulleropyrrolidineeglycopyranosylaminopyrimidin-4-
10
11
12
S
H
H
CH
H
one conjugates
S
Compounds 7e12 were obtained in one step from 1,3-dipolar
cycloaddition reactions of C60 with azomethine ylides Y, which
were generated in situ by the reaction of the 5-formylpyrimidin-
Table 2
Selected H NMR spectroscopic data for the fulleropyrrolidine derivatives
7e12
1
5
a
4
-one derivatives 1e6 with N-methylglycine in refluxing tol-
8
uene (Scheme 1). Fullerene derivatives 7e12 were obtained
in moderate yields as mixtures of two diastereoisomers, which
were separated by column chromatography on silica gel. The di-
astereoisomers, which differ in the configuration of the pyrroli-
Compound N(1)eMe H-2
H-5a (J/Hz) H-5b (J/Hz) NH (J/Hz)
7
7
a
2.79
2.69
2.78
2.68
2.75
2.69
2.77
2.70
2.77
2.70
2.86
2.91
5.53 4.25 (9.7)
5.60 4.19 (9.5)
5.51 4.24 (9.5)
5.58 4.19 (9.5)
5.51 4.24 (9.6)
5.59 4.19 (9.5)
5.53 4.25 (9.7)
5.61 4.20 (9.6)
5.52 4.26 (9.6)
5.59 4.46 (9.6)
5.57 4.19 (9.6)
5.59 4.32 (9.7)
4.99 (9.7)
4.97 (9.5)
4.99 (9.5)
4.24 (9.5)
4.99 (9.6)
4.98 (9.5)
5.00 (9.7)
4.99 (9.6)
4.99 (9.6)
4.98 (9.6)
4.97 (9.6)
4.91 (9.7)
9.15 (10.5)
9.41 (9.2)
9.14 (10.4)
9.38 (9.2)
9.19 (10.4)
9.55 (9.5)
9.21 (10.3)
9.58 (9.2)
9.36 (10.8)
9.71 (9.3)
9.55 (8.9)
9.81 (9.8)
b
8a
8
9
9
1
1
b
dine carbon C-2, were identified as a (higher R on silica) and
f
b (lower R ). Typically the main isomer is the one with lower
f
a
b
R value on silica, except for compound 12 (Table 1). Each dia-
f
0a
0b
1
13
stereoisomer was characterised by H and C NMR and MS,
and the structure of 10awas unequivocallydetermined bymeans
of single-crystal X-ray diffraction studies.
11a
1
1
1
1b
2a
2b
2
.1.1. NMR studies
1
The H NMR spectra of the conjugates 7e12 show the
typical resonance of the N(1)eMe protons as singlets at
d 2.68e2.79 ppm; compound 12b is an exception because
the resonance of those protons appears at d 2.91 ppm (Table
2.1.2. MS studies
The molecular mass of compounds 7e12 was initially deter-
mined by Liquid Secondary Ion Mass Spectrometry in an EBEQ
þ
2
a singlet at d 5.51e5.61 ppm while the resonances of the
). The resonance corresponding to proton H-2 appears as
mass spectrometer. All spectra showed the [MþH] ions and
a fragment of m/z 720 corresponding to the intact fullerene moi-
ety. However, in order to differentiate between each pair of
diastereoisomers, as high collision energy conditions are
9
two diastereotopic protons H-5 appear as doublets at
d 4.19e4.46 (H-5a) and 4.91e5.00 ppm (H-5b), with a cou-
pling constant of 9.5e9.7 Hz. Surprisingly, in the spectrum
of diastereoisomer 8b the resonance corresponding to H-5b
appears at a much higher field (d 4.24 ppm) than that observed
1
0
usually insensitive to stereochemical differences, instruments
with low energy collision regimes (Q-Tof and Ion Trap) and
another ionisation technique (electrospray) were used. Using
the latter instruments, the spectra obtained for all compounds
0
for other compounds. The resonance of the 6 -NH proton ap-
pears as a doublet at d 9.14e9.81 ppm with a coupling con-
stant in the range of 8.9e10.8 Hz.
þ
show predominantly the protonated molecules [MþH] .
þ
The [MþH] ions were selected and subjected to low en-
1
Inthe CNMRspectra ofthe conjugates7e12, theresonance
3
ergy collisions in the same experimental conditions, both
with the Q-Tof and with the Ion Trap instruments. For each
compound, two diagnostic fragment ions are obtained: the
ion formed by elimination of acetic acid from the glycosidic
0
0
of the C-1 carbon of the sugar moiety appears at d 79.3e
3
8
C-4 appear, respectively, at d 75.8e76.3 and d 76.2e77.6 ppm.
0.6 ppm while the resonances of the C -sp carbons C-3 and
60
O
O
O
R1
CHO
NH
R1
H
R1
3 4
* 2
5
C + CH
2
4'
N
N
5'
' 6'
N
Me
N
3'
N
2
'
1
Me
NH
MeX
N
MeNHCH CO H
toluene, reflux
C60
MeX
N
2
2
MeX
N
2
2
NH
1''
R
2
R
R
O
O
OAc
O
OAc
OAc
7-12
OAc
OAc
OAc
OAc
-6
OAc
OAc
Y
1
Scheme 1.

C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
4429
þ
moiety, [(MþH)ꢀAcOH] , and the ion with m/z 776 formed
is usually involved. In the present case, the relative abundances
of the two diagnostic ions allow a rapid and easy differentiation
of the diastereoisomers as it can be seen in Figure 1 for the
pair 10a and 10b.
by loss of a neutral fragment through heterolytic cleavage
0
of the C-2eC-5 carbon bond (Scheme 2). Under these
conditions, the intact fullerene moiety is not observed in
almost all spectra and, when present, its relative abundance
is low.
For the diastereoisomers 7ae12a, the most abundant frag-
ment ions are formed by losses of AcOH, whereas for the dia-
stereoisomers 7be12b, the formation of the ion with m/z 776
competes favourably with acetic acid loss. To our knowledge,
this is the first case where diastereoisomers of fullerene deriva-
2
tives are differentiated by MS of their protonated molecules.
The increased relative abundance of the m/z 776 ion for the
diastereoisomers 7be12b, when compared with their 7ae
O
H
R1
N
N
Me
N
12a counterparts, may be due to a less favourable configura-
Me
MeX
N
tion of the former due to the bulky leaving neutral group being
closer to the fullerene cage.
2
NH
m/z 776
R
O
OAc
OAc
-12
[
M+H]+
OAc
7
2.1.3. Single-crystal X-ray crystallographic studies
Scheme 2.
To the best of our knowledge, and according to a search in the
Cambridge Structural Database (CSD, Version 5.28dAugust
1
6,17
Differentiation of diastereoisomers by collision induced
fragmentation in mass spectrometry is not very common and
it usually relies on the formation of adducts, complexes or
2007),
compound 10a is the first C derivativewith a nucleo-
60
side-type unit. Moreover, only a couple of related nucleoside
crystal structures are available in the literature, namely those
described by Ferguson et al. for 6-methyl-5-methoxy-3-
(2,3,4,6-tetra-O-acetyl-b-D-glucopyranos-1-yl)-3H-1,2,3-tri-
1
1,12
derivatised species, either in situ
1
or prior to the introduction
and, when applied directly to
3,14
in the mass spectrometer
n
15
18
protonated molecules, multiple stage mass analysis MS (n>2)
azolo[4,5-d]pyrimidin-7(6H)-one and 2-methylthio-5-nitroso-
2
þ
Figure 1. Product ion spectra (MS ) of the [MþH] ions of diastereoisomers 10a and 10b.

4430
C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
˚
˚
˚
ꢁ
6
4
-N-(2,3,4-tri-O-acetyl-b-D-xylopyranosyl)aminopyrimidin-
ring are: Q¼0.619 A, q ¼0.089 A, q ¼0.613 A, 4 ¼6.7 and
2
3
2
1
9
ꢁ
(3H)-one.
Compound 10a crystallises in the orthorhombic non-centro-
symmetric and chiral P2 2 2 space group, in a similar way as
q¼8.3 . These findings further support the presence of a slightly
distorted chair conformation for the substituted glycopyranosyl
ring since, on the one hand, the puckering amplitude q is signif-
1
1 1
3
described for the couple nucleoside units available in the litera-
1
icantly higher than q and, on the other, the total puckering am-
plitude Q is only slightly lower than the calculated for the ideal
2
8,19
ture.
The asymmetric unit is composed of a single molecule
˚
cyclohexane chair (0.63 A based on an ideal CeC interatomic
˚
distance of 1.54 A). Interestingly, the magnitude of the distor-
tion in 10a reflects the crystal packing arrangement of individ-
ual molecular units (see below), imposing significant strain in
the glycopyranosyl ring, which is ultimately described by
of 10a plus an undetermined number of solvent molecules,
which were found to be composed of partially occupied chloro-
form and toluene. Indeed, even though difference Fourier maps
allowed to partially unveil the location of these crystallisation
chemical moieties, full structural refinement was found to be
rather unstable and their corresponding contribution to the elec-
tron density was ultimately removed in order to reach the sensi-
ble structural model reported here (see details in the appropriate
section). Figure 2 depicts a view of the molecular unit of 10a,
with all non-hydrogen atoms being represented as thermal ellip-
soids (50% of probability). The b configuration of the anomeric
carbon atom of the substituted glucopyranosyl ring was known
ꢁ
a value of q (8.3 ) greater than the one for the ideal cyclohexane
20
ꢁ
chair conformation (calculated as ca. 5 ). The pyrimidine ring
is, as expected, almost planar with the six defining atoms being
˚
in average 0.013 A displaced from the plane of the ring. The
substituent methyl and methylthio groups are approximately
co-planar with the pyrimidine ring, exhibiting dihedral angles
ꢁ
of about 1.9 and 5.7 , respectively.
a priori, and in the crystal structure of 10a this ring significantly
4
Following the assumptions from the synthesis, the C60 deriv-
atives 10 were obtained as a mixture of two diastereoisomers
(see Scheme 1) with carbon 2 exhibiting distinct configurations.
The crystal structural determination of compound 10a clearly
supports the presence of configuration R for this chirality centre.
approaches the near-ideal C chair conformation with all the
1
carbonyl groups of the acetyl substituents being cis with respect
to the adjacent CeH groups, either of the six-membered ring or
of the eCH e substituent (Fig. 2). The puckering parameters
2
2
calculated after Cremer and Pople for this six-membered
0
19
As also pointed out by Cobo et al., in 10a the bridging
eNHe moiety of the glucopyranosylaminopyrimidin-4-one
˚
unit establishes a rather strong [d(D/A) of 2.733(3) A] and
ꢁ
reasonably directional [:(DHA) of 140(2) ] intramolecular
NeH/N hydrogen-bonding interaction with the eNMee moi-
ety belonging to the C2/C5 ring bound to C60 (not shown).
However, in the particular structure of 10a, it is also of consider-
able importance to emphasise that the eNHe moiety is further
involved in a secondary, but weaker, hydrogen-bonding interac-
tion with a neighbouring substituent acetyl group of the gluco-
˚
pyranosyl ring: NeH/O with d(D/A) of 3.054(3) A and
ꢁ
:
(DHA) of 119(2) . These two interactions can also be de-
2
1
scribed as S(5) and S(6), respectively, graph set motifs. It is
thus feasible to assume that if the eNHe group was not directly
involved in bifurcated hydrogen bonds, the former interaction
could be significantly more linear and, consequently, stronger.
In summary, the mutual spatial arrangement between the gluco-
pyranosyl and pyrimidine rings, which ultimately subtend an
ꢁ
approximate dihedral angle of about 54 between the average
planes containing the rings, is such that, on one hand, it maxi-
mises the two aforementioned hydrogen-bonding interactions
and, on the other hand, it minimises the steric repulsion between
all functional groups composing the molecular unit of 10a.
Individual molecules of 10a close pack in the solid state
along the [100] crystallographic direction, forming infinite
tapes following the symmetry of the 2 screw axes (Fig. 3a).
1
Noteworthy is the fact that while the C60 moieties point out-
wards, the glucopyranosylaminopyrimidin-4-one units consti-
tute the main core of these tapes, with a significant number
of weak CeH/(N,O) hydrogen-bonding interactions estab-
lishing the physical links between neighbouring moieties.
These supramolecular tapes are distributed in the crystal
structure of compound 10a in a typical herringbone fashion
(Fig. 3c), most certainly mediated by a significant number of
Figure 2. Molecular unit of the crystal structure of compound 10a. Non-hydro-
gen atoms are represented as thermal ellipsoids drawn at the 50% probability
level and hydrogen atoms as small spheres with arbitrary radii.

C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
4431
Figure 3. (a) and (b) Parallel distribution of individual molecular units of 10a, leading to the formation of a supramolecular tape assembled by a series of weak but
cooperative CeH/(N,O) hydrogen-bonding interactions (green dashed lines) involving adjacent glucopyranosylaminopyrimidin-4-one units. (c) Crystal packing
viewed in perspective along the [100] crystallographic direction.
weak interactions involving the solvent molecules of crystalli-
sation (which could not be located), plus CeH/p contacts.
For further details on crystal solution and refinement see
Section 4.3 below.
to the low yield of this reaction. Deprotection of the hydroxyl
groups in dyad 16 with trifluoroacetic acid afforded dyad 17 in
excellent yield (96%).
1
13
Compounds 14e17 were characterised by H and C NMR
and MS. The NMR spectra of these compounds confirm their
structures and the mass spectra show the expected molecular
2
.2. Fullereneeuridine conjugates
1
ions. In the H NMR spectra of compounds 14e17, the reso-
nances of protons H-5 and H-6 appear as doublets at
The synthesis of the fullereneeuridine conjugates 16 and
0
1
7 involved, as the first step, the protection of the 2 - and
0
d 5.63e5.78 ppm, with a coupling constant of 8.0e8.4 Hz.
0
3
and using p-toluenesulfonic acid (PTSA) as the catalyst
-hydroxyl groups of uridine (13) by reaction with acetone
The resonance corresponding to H-1 appears as a doublet at
d 5.67e5.82 ppm with a coupling constant of 2.0e2.3 Hz (for
compound 17, a higher coupling constant (5.7 Hz) is observed).
0
0
22
(
7
Scheme 3). 2 ,3 -O-Isopropylideneuridine (14), obtained in
4% yield, was then reacted with methyl 3-chloro-3-oxopro-
panoate to afford malonate 15 in 77% yield. This malonate
1
3
In the C NMR spectra of compounds 14e16, the resonances of
C-5 and C-6 appear at d 102.4e102.9 and 142.2e142.5 ppm,
0
was covalently linked to C , following a modification of
6
respectively. The resonance of carbon C-1 appears typically
at d 94.62e95.48 ppm.
0
2
3
Bingel’s procedure, to yield the conjugate 16. This com-
pound was purified by flash chromatography (silica gel) using
toluene as the eluent and crystallised from chloroform/metha-
nol yielding a black solid (17% yield). The yields of the cyclo-
propanation reactions of fullerene with malonates are typically
low but, in this particular case, the reactivity of uridine deriv-
3. Conclusions
Fullerene derivatives bearing a 4-(b-D-glycopyranosyl-
amino)pyrimidin-4-one moiety can be easily synthesised
from the corresponding 5-formylpyrimidin-4-one derivatives,
2
4
atives with iodine and nucleophiles may also be contributing

4432
C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
O
N
O
O
N
HN
HN
HN
O
O
O
O
N
O
O
acetone,
PTSA
O
O
O
O
O
MeO
NEt , CH Cl
2
Cl
HO
HO
MeO
O
74%
3
7
2
7%
HO
OH
O
O
O
13
14
15
I , C
2
60
1
7%
toluene
O
O
N
4
HN
5
6
HN
2
1
N
O
O
O
O
O
O
5
'
'O
O
4
1'
' 2'
MeO
O
MeO
O
3
TFA/H O
2
HO
OH
(9/1)
O
O
9
6%
17
16
Scheme 3.
C60 and N-methylglycine. These reactions afford mixtures of
two diastereoisomers, which can be separated by column chro-
matography. The study of the gas-phase fragmentations of
these diastereoisomers allows their differentiation. Single-
crystal X-ray crystallography of one of the fullereneeglyco-
pyranosylaminopyrimidin-4-one conjugates (10a) shows that
individual molecules close pack in the solid state forming
infinite tapes. The main core of these tapes is constituted by
the glycopyranosylaminopyrimidin-4-one units while the C60
moieties point outwards. These supramolecular tapes are dis-
tributed in the crystal structure of the compound in a typical
herringbone fashion. The first C euridine conjugate was
massspectrawereacquiredwithtwodifferent instruments:aMi-
cromass Q-Tof 2 (Micromass, Manchester, UK) and a Finnigan
LXQ ion trap (Thermo Finnigan, San Jose, CA, USA). Electro-
spray mass spectra were obtained from methanol/1% formic
acid solutions. For the Q-Tof 2, source and desolvation temper-
atures were 80 and 150 C, respectively, and capillary voltage
was 3000 V. The spectra were acquired at cone voltages of
35 V. Nebulisation and collision gases were N and Ar, respec-
2
ꢁ
2
þ
tively. MS spectra were acquired by selecting the [MþH] ions
with the quadrupole and using the hexapole as collision cell
(between 40 and 80 eV). Ion trap experimental parameters for
ꢁ
the ESI were: capillary temperature and voltage 350 C and
1 V, respectively, tube lens voltage 40 V and nitrogen sheath
2
gas 30 psi. MS spectra were acquired by selecting and exciting
6
0
prepared in five steps from commercial uridine.
þ
4
. Experimental
the [MþH] ions by standard isolation and excitation
procedures.
4
.1. General remarks
4
.3. Single-crystal X-ray crystallographic studies
1
H NMR spectra were recorded on a Bruker Avance 300
1
3
spectrometer at 300.13 MHz. C NMR spectra were recorded
on Bruker Avance 300 or Bruker Avance 500 spectrometer at
5.47 or 125.77 MHz, respectively. Chemical shifts (d) are
A suitable single crystal of compound 10a was mounted on
a Hampton Research CryoLoop using FOMBLIN Y perfluoro-
polyether vacuum oil (LVAC 25/6) purchased from Aldrich,
2
5
7
quoted in parts per million relativeto TMS and the coupling con-
stants (J) are expressed in hertz (Hz). Melting points were
measuredonaReichertThermovarapparatusfittedwithamicro-
scope and are uncorrected.
with the help of a Stemi 2000 stereomicroscope equipped
with Carl Zeiss lenses. Data were collected at 100(2) K on
a Bruker X8 Kappa APEX II charge-coupled device (CCD)
area-detector diffractometer (Cu Ka graphite-monochromated
˚
radiation, l¼1.54178 A) controlled by the APEX2 software
2
6
package, and equipped with an Oxford Cryosystems Series
4
.2. Mass spectrometric studies
700 cryostream monitored remotely using the software interface
Cryopad. Images were processed using the software package
2
7
LSIMS mass spectra were obtained with a VG Autospec Q
VG Analytical, Manchester, UK) instrument, equipped with
a caesium ion gun (2 mA at 20 kV). The accelerating voltage
was 8 kV. m-Nitrobenzyl alcohol was used as matrix. ESI
2
8
(
SAINTþ, and data were corrected for absorption by the multi-
2
9
scan semi-empirical method implemented in SADABS. The
structure was solved using the direct methods implemented in

C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
Table 3
4433
3
0
SHELXS-97, which ultimately allowed the immediate loca-
tion of the majority of the heaviest atoms, including those
belonging to the C60 moiety. The remaining non-hydrogen
atoms were directly located from difference Fourier maps calcu-
lated from successive full-matrix least squares refinement
Crystal and SQUEEZE structural refinement data for fulleropyrrolidine
derivative 10a
Formula
83 32 4 10
C H N O S
Crystal system
Space group
Orthorhombic
2
31
1 1 1
P2 2 2
cycles on F using SHELXL-97. All non-hydrogen atoms
were successfully refined using anisotropic displacement pa-
rameters. Friedel pairs (a total of 6590) have not been merged
and were counted as independent data during the refinement
stages.
˚
a/A
12.5427(4)
14.1930(5)
˚
b/A
˚
c/A
Volume/A˚
33.3711(10)
5940.7(3)
3
Z
4
1.428
0.129
ꢀ
3
D /g cm
m(Mo Ka)/mm
c
Even though the vast majority of the hydrogen atoms at-
tached to carbon were markedly visible in difference Fourier
maps, they have been instead located at their idealised positions
ꢀ
1
Crystal size/mm
Crystal type
q Range
0.45ꢂ0.45ꢂ0.40
Black blocks
3.52e29.13
31
using appropriate HFIX instructions in SHELXL-97: 13 and
2
1
3 for the tertiary and secondary carbon atoms, respectively;
37 for the terminal methyl groups. In the case of the NeH moi-
Index ranges
Reflections collected
ꢀ15ꢃhꢃ15, ꢀ19ꢃkꢃ19, ꢀ45ꢃlꢃ45
102,789
Independent reflections
Completeness to q¼29.13
14,844 (Rint¼0.0609)
94.2%
ety, the hydrogen atom was instead added at the position of the
observable Q peak, with the corresponding NeH distance being
˚
restrained to 0.95(1) A in order to ensure a chemically reason-
able geometry for this moiety. All these hydrogen atoms were
included in the final structural model in subsequent refinement
cycles in riding-motion approximation with isotropic thermal
displacement parameters (U ) fixed at 1.2 or 1.5 (only for
iso
the eCH and eNH moieties) times U of the carbon (or nitro-
gen) atom to which they are attached.
ꢁ
a,b
Final R indices [I>2s(I)]
R1¼0.0546, wR2¼0.1163
R1¼0.0806, wR2¼0.1250
m¼0.0640, n¼0
a,b
Final R indices (all data)
c
Weighting scheme
Largest diff.
ꢀ3
˚
0.441 and ꢀ0.231 e A
peak and hole
P
P
a
R1 ¼
wR2 ¼
jjF0j ꢀ jFcjj= jF0j.
qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi
P
P
b
c
2
2
2
2
2
½wðF0 ꢀ FcÞ ꢄ= ½wðF0Þ ꢄ.
3
eq
2
2
0
2
2
0
2
c
w ¼ 1=½s ðF Þ þ ðmPÞ þ nPꢄ where P ¼ ðF ꢀ 2F Þ=3.
During crystal refinement using the original integrated and
scaled dataset, it was clearly visible from difference Fourier
maps that individual molecules of 10a close pack in the solid
state with a number of highly disordered solvent molecules, in
particular an undetermined number of chloroform and toluene
molecules. Attempts to model these solvent chemical moieties
using a battery of crystallographic constraints proved to be
unfruitful. Indeed, the significant smeared-out electron density
arising from the extensive structural disorder associated with
these moieties created instability during refinement, with corre-
sponding very large R factors: R1¼0.1433 and wR2¼0.3966.
12 Union Road, Cambridge CB2 2EZ, UK. Fax: þ44 1223
336033; E-mail: deposit@ccdc.cam.ac.uk.
4.4. Synthesis of the fulleropyrrolidine derivatives 7e12:
general procedure
A solution of C60 (100 mg, 0.14 mmol), N-methylglycine
5
a
(18 mg,
0.20 mmol)
and
5-formylpyrimidin-4-one
(0.068 mmol) in toluene (100 mL) was heated at reflux under
N2 for 10 h. A new portion of N-methylglycine (9 mg,
0.10 mmol) was added to the reaction mixture and it was re-
fluxed for 10 h more. This last procedure was repeated twice.
The reaction mixture was concentrated and purified by col-
umn chromatography using a gradient of toluene to toluene/
ethyl acetate (8:2) as the eluent. The first fraction was the un-
changed C60 and the second and third fractions were the two
diastereoisomeric cycloadducts. Some unchanged 5-formyl-
pyrimidin-4-ones were also recovered.
3
2
The original dataset was then treated using the SQUEEZE
3
3,34
subroutines provided with the software package PLATON
in order to eliminate the contribution of the molecules present
in the solvent-accessible area to the overall electron density.
3
˚
PLATON estimated that the unit cell contains ca. 1025 A of po-
tential solvent-accessible area (ca. 17% of the total volume), dis-
tributed mainly across two large (but symmetry-related) cavities
1
centred at(00.934 3/4)andat(½0.240 ⁄ ), andcontainingatotal
4
of ca. 220 electrons. The resulting solvent-free reflection file
produced by PLATON was used for subsequent refinement by
4.5. Characterisation of the fulleropyrrolidinee
glycopyranosylaminopyrimidin-4-one conjugates
2
full-matrix least squares on F using SHELXL-97, which ulti-
31
mately allowed a much more reliable and stable convergence.
3
5,36
The Flack parameter was refined to 0.04(8),
thus supporting
4.5.1. Compound 7a
1
ꢁ
the assumption of the presence of an enantiopure compound.
Information concerning crystallographic data collection and
structural refinement details using the SQUEEZE (solvent-free)
data is summarised in Table 3. Crystallographic data (excluding
structural factors) for the structure reported in this paper have
been deposited with the Cambridge Crystallographic Data Cen-
tre as supplementary publication no. CCDC-641402. Copies of
the data can be obtained free of charge on application to CCDC,
Mp >300 C. H NMR (300.13 MHz, CHCl ): d¼1.98, 2.03,
3
2.08 (3s, 3ꢂ3H, 3ꢂAcO), 2.58 (s, 3H, SCH ), 2.79 (s, 3H,
3
N(1)eCH ), 3.38 (t, J¼10.8 Hz, 1H, H-sugar), 3.44 (s, 3H,
3
0
N(3 )eCH ), 4.16e4.21 (m, 1H, H-sugar), 4.25 (d, J¼9.7 Hz,
3
1H, H-5), 4.99 (d, J¼9.7 Hz, 1H, H-5), 5.10e5.14 (m, 1H,
H-sugar), 5.27e5.38 (m, 2H, H-sugar), 5.53 (s, 1H, H-2), 5.70
C
1
3
(t, J¼8.9 Hz, 1H, H-sugar), 9.15 (d, J¼10.5 Hz, 1H, NH).
NMR (75.47 MHz, CDCl ): d¼15.0 (CH ), 20.7, 20.8, 21.5
3
3

4434
C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
0
0
(
6
(
1
1
1
7
3ꢂCH C]O), 30.4 (N(3 )eCH ), 40.1 (N(1)eCH ), 64.2,
(3ꢂCH C]O), 27.8 (N(3 )eCH ), 39.7 (N(1)eCH ), 55.3
3
3
3
3
3
3
3
9.0, 69.2, 69.5, 70.9, 73.7, 75.8, 76.2 (2ꢂC -sp ), 80.6
(OCH ), 64.1, 69.2, 69.3, 69.4, 70.9, 73.1, 75.2, 76.1, 77.6
3
6
0
0
0
0
3
00
0
C-1 ), 92.9 (C-5 ), 105.3, 137.2, 139.7, 141.5, 141.9, 142.0,
(2ꢂC -sp ), 80.1 (C-1 ), 89.2 (C-5 ), 134.8, 136.1, 136.3,
6
0
42.2, 142.3, 142.6, 142.9, 144.3, 145.1, 145.3, 145.5, 145.7,
46.1, 146.2, 146.6, 147.1, 153.2, 153.4, 155.2, 157.9, 162.0,
69.9, 170.3 (3ꢂCH C¼O). MS (LSIMS) m/z 1205 [MþH] ,
137.9, 139.3, 139.96, 140.00, 141.3, 141.6, 141.7, 142.0,
142.05, 142.07, 142.2, 142.25, 142.29, 142.3, 142.36, 142.44,
142.6, 143.1, 144.3, 144.4, 144.5, 144.6, 145.0, 145.18,
145.22, 145.25, 145.27, 145.3, 145.4, 145.7, 145.88, 145.90,
þ
3
ꢅ
þ
20 [C ] .
6
0
145.98, 146.0, 146.1, 146.3, 146.5, 147.1, 147.2, 147.3, 152.0,
153.4, 155.2, 155.9, 157.0, 158.4, 163.5, 169.78, 169.82,
4
.5.2. Compound 7b
ꢁ
1
þ
Mp >300 C. H NMR (300.13 MHz, CHCl ): d¼2.01,
170.3 (3ꢂCH C]O). MS (LSIMS) m/z 1189 [MþH] , 720
3
3
ꢅ
[C ] .
þ
2
3
3
.07, 2.18 (3s, 3ꢂ3H, 3ꢂAcO), 2.55 (s, 3H, SCH ), 2.69 (s,
3
60
H, N(1)eCH ), 3.25 (t, J¼9.2 Hz, 1H, H-sugar), 3.45 (s,
3
0
H, N(3 )eCH ), 3.88e3.94 (m, 1H, H-sugar), 4.19 (d,
3
J¼9.5 Hz, 1H, H-5), 4.97 (d, J¼9.5 Hz, 1H, H-5), 4.94e
4.5.5. Compound 9a
ꢁ
1
5
.00 (m, 1H, H-sugar), 5.24 (t, J¼9.2 Hz, 1H, H-sugar), 5.35
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.96,
3
(
5
(
t, J¼9.2 Hz, 1H, H-sugar), 5.52 (t, J¼9.2 Hz, 1H, H-sugar),
2.00, 2.06, 2.12 (4s, 4ꢂ3H, 4ꢂAcO), 2.76 (s, 3H,
1
3
0
.60 (s, 1H, H-2), 9.41 (d, J¼9.2 Hz, 1H, NH). C NMR
N(1)eCH ), 3.35 (s, 3H, N(3 )eCH ), 3.81 (ddd, J¼9.9, 4.4,
3
3
75.47 MHz, CDCl ): d¼14.9 (SCH ), 20.69, 20.73, 20.8
2.0 Hz, 1H, H-sugar), 4.03 (s, 3H, OCH ), 4.19e4.33 (m,
3
3
3
0
(
6
3ꢂCH C]O), 30.3 (N(3 )eCH ), 39.7 (N(1)eCH ), 64.1,
3H, H-5 and 2ꢂH-sugar), 4.99 (d, J¼9.6 Hz, 1H, H-5),
5.21e5.30 (m, 1H, H-sugar), 5.32e5.40 (m, 2H, H-sugar),
5.51 (s, 1H, H-2), 5.70e5.76 (m, 1H, H-sugar), 9.19 (d,
3
3
3
3
9.2, 69.4, 70.8, 73.1, 75.1, 76.0, 76.2 (2ꢂꢂC -sp ), 80.2
6
0
00 0
(
C-1 ), 91.2 (C-5 ), 134.8, 136.0, 136.3, 136.9, 140.0, 140.1,
1
3
1
1
1
1
41.2, 141.6, 142.0, 142.2, 142.28, 142.34, 142.5, 142.45,
42.54, 142.9, 143.1, 144.4, 145.0, 145.3, 145.4, 145.7,
45.9, 146.0, 146.1, 146.3, 146.4, 146.5, 147.0, 147.3,
51.8, 153.3, 155.0, 156.9, 157.3, 162.9, 169.7, 169.8, 170.3
J¼10.4 Hz, 1H, NH).
C NMR (75.47 MHz, CDCl ):
3
0
d¼20.6, 20.7, 20.8, 21.4 (4ꢂCH C]O), 27.9 (N(3 )eCH ),
3
3
0
0
39.8 (N(1)eCH ), 55.4 (OCH ), 62.0 (C-6 ), 68.5, 69.0,
3
3
0
0
69.4 (C-5), 70.7, 73.0 (C-5 ), 74.2, 75.8 (C-2), 76.3
þ
ꢅ
þ
3
00 0
(C -sp ), 80.1 (C-1 ), 91.1 (C-5 ), 134.4, 136.1, 136.7,
60
(
3ꢂCH C]O). MS (LSIMS) m/z 1205 [MþH] , 720 [C ] .
3
60
137.2, 139.4, 139.8, 140.08, 140.13, 141.46, 141.49, 141.7,
4
.5.3. Compound 8a
1
141.9, 142.0, 142.1, 142.2, 142.27, 142.27, 142.30, 142.48,
142.53, 142.6, 142.90, 142.92, 144.36, 144.43, 144.6,
144.94, 145.00, 145.1, 145.3, 145.4, 145.46, 145.54, 145.7,
145.9, 145.96, 145.99, 146.1, 146.2, 146.5, 146.7, 147.18,
147.23, 153.3, 153.4, 155.3, 155.8, 156.2, 158.9, 163.6,
ꢁ
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.97,
3
2
3
.03, 2.07 (3s, 3ꢂ3H, 3ꢂAcO), 2.78 (s, 3H, N(1)eCH ),
3
0
.34 (s, 3H, N(3 )eCH ), 3.38e3.49 (m, 1H, H-sugar), 4.03
3
(
(
5
s, 3H, OCH ), 4.19 (dd, J¼11.4, 5.6 Hz, 1H, H-sugar), 4.24
3
d, J¼9.6 Hz, 1H, H-5), 4.99 (d, J¼9.6 Hz, 1H, H-5), 5.05e
169.5, 169.8, 170.4, 170.6 (4ꢂCH C]O). MS (LSIMS) m/z
3
þ
ꢅ
þ
.14 (m, 1H, H-sugar), 5.27e5.39 (m, 2H, 2ꢂH-sugar), 5.51
1261 [MþH] , 720 [C ] .
6
0
(
s, 1H, H-2), 5.62e5.69 (m, 1H, H-sugar), 9.14 (d,
1
3
J¼10.4 Hz, 1H, NH). C NMR (125.77 MHz, CDCl ):
3
0
d¼20.7, 20.8, 21.5 (3ꢂCH C]O), 27.9 (N(3 )eCH ), 40.0
4.5.6. Compound 9b
1
3
3
ꢁ
(
N(1)eCH ), 55.4 (OCH ), 64.2, 69.0, 69.2, 69.5, 70.9, 73.7,
3
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.89,
3
3
3
00
0
7
1
1
1
1
1
1
1
5.9, 76.3, 77.6 (2ꢂC -sp ), 80.6 (C-1 ), 91.0 (C-5 ), 134.4,
2.00, 2.05, 2.16 (4s, 4ꢂ3H, 4ꢂAcO), 2.69 (s, 3H,
6
0
0
36.1, 136.7, 137.2, 139.4, 139.8, 140.06, 140.13, 141.45,
41.49, 141.7, 141.9, 142.0, 142.2, 142.3, 142.48, 142.53,
42.56, 142.58, 142.88, 142.92, 144.3, 144.4, 144.9, 144.99,
45.09, 145.2, 145.3, 145.37, 145.40, 145.46, 145.53, 145.7,
45.9, 145.95, 145.99, 146.0, 146.1, 146.2, 146.55, 146.64,
47.3, 153.3, 153.5, 155.3, 155.9, 156.2, 158.9, 163.6,
N(1)eCH ), 3.35 (s, 3H, N(3 )eCH ), 3.70 (ddd, J¼9.9, 4.4,
3
3
0
0
00
1.9 Hz, 1H, H-5 ), 3.82 (dd, J¼12.2, 1.9 Hz, 1H, H-6 ),
4.00 (s, 3H, OCH ), 4.20 (d, J¼9.5 Hz, 1H, H-5), 4.98 (d,
3
J¼9.5 Hz, 1H, H-5), 5.12 (t, J¼9.5 Hz, 1H, H-sugar), 5.31
(t, J¼9.5 Hz, 1H, H-sugar), 5.38 (t, J¼9.5 Hz, 1H, H-sugar),
5.59 (s, H-2, 1H), 5.65 (t, J¼9.5 Hz, 1H, H-sugar), 9.55 (d,
1
3
69.9, 170.0, 170.3 (3ꢂCH C]O). MS (LSIMS) m/z 1189
J¼9.5 Hz, 1H, NH).
C NMR (125.77 MHz, CDCl ):
3
3
þ
ꢅ
þ
0
[
MþH] , 720 [C ] .
d¼20.6, 20.67, 20.70, 20.8 (4ꢂCH C]O), 27.9 (N(3 )e
6
0
3
CH ), 39.8 (N(1)eCH ), 55.3 (OCH ), 62.2, 68.6, 69.1,
3
3
3
3
4
.5.4. Compound 8b
1
69.3, 70.7, 73.1, 73.6, 75.2, 76.2, 76.6 (2ꢂC -sp ), 79.3 (C-
6
0
ꢁ
00
0
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼2.01, 2.07,
1 ), 89.0 (C-5 ), 139.9, 140.05, 140.10, 141.47, 141.52,
141.6, 141.8, 141.96, 142.04, 142.1, 142.2, 142.27, 142.29,
142.4, 142.5, 142.6, 142.8, 142.9, 144.3, 144.4, 144.5,
144.6, 144.9, 145.0, 145.22, 145.24, 145.31, 145.32, 145.4,
145.66, 145.70, 145.9, 145.97, 146.01, 146.15, 146.17,
146.18, 146.45, 146.54, 147.0, 147.2, 147.3, 152.1, 153.3,
155.1, 155.9, 156.8, 158.0, 163.5, 169.4, 169.7, 170.3, 170.7
3
2
.17 (3s, 3ꢂ3H, 3ꢂAcO), 2.68 (s, 3H, N(1)eCH ), 3.28 (t,
3
0
J¼11.0 Hz, 1H, H-sugar), 3.34 (s, 3H, N(3 )eCH ), 3.91 (dd,
3
J¼11.4, 5.7 Hz, 1H, H-sugar), 4.01 (s, 3H, OCH ), 4.19 (d, J¼
3
9
.5 Hz, 1H, H-5), 4.95e5.03 (m, 2H, H-5 and H-sugar), 5.24 (t,
J¼9.2 Hz, 1H, H-sugar), 5.36 (t, J¼9.2 Hz, 1H, H-sugar), 5.49
(
1
t, J¼9.2 Hz, 1H, H-sugar), 5.58 (s, 1H, H-2), 9.38 (d, J¼9.2 Hz,
1
3
þ
ꢅ
þ
H, NH). C NMR (125.77 MHz, CDCl ): d¼20.7, 20.8, 20.9
(4ꢂCH C]O). MS (LSIMS) m/z 1261 [MþH] , 720 [C ] .
3
3
60

C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
4435
4
.5.7. Compound 10a
144.6, 145.02, 145.04, 145.1, 145.20, 145.24, 145.3, 145.45,
145.49, 145.6, 145.9, 146.0, 146.06, 146.11, 146.2, 146.5,
146.78, 146.81, 147.2, 147.3, 152.8, 153.4, 155.5, 155.9,
ꢁ
1
Mp >300 C. H NMR (300.13 Hz, CDCl ): d¼1.98, 2.01,
3
2
3
4
.07, 2.12 (4s, 4ꢂ3H, 4ꢂAcO), 2.58 (s, 3H, SCH ), 2.77 (s,
3
0
H, N(1)eCH ), 3.46 (s, 3H, N(3 )eCH ), 3.78 (ddd, J¼9.8,
160.3, 161.2, 165.3, 169.5, 169.8, 170.3, 170.6 (4ꢂCH C]O).
3
3
3
þ
ꢅ
þ
.7, 2.7 Hz, 1H, H-sugar), 4.18e4.32 (m, 3H, H-5 and 2ꢂ
MS (LSIMS) m/z 1263 [MþH] , 720 [C ] .
6
0
0
0
H-6 ), 5.00 (d, J¼9.7 Hz, 1H, H-5), 5.19e5.26 (m, 1H, H-
sugar), 5.31e5.40 (m, 2H, H-sugar), 5.53 (s, 1H, H-2), 5.73e
5
4.5.10. Compound 11b
1
3
ꢁ
1
.79 (m, 1H, H-sugar), 9.21 (d, J¼10.3 Hz, 1H, NH).
C
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.85,
3
NMR (125.77 MHz, CDCl ): d¼20.60, 20.64, 20.7, 21.4
1.99, 2.04, 2.16 (4s, 4ꢂ3H, 4ꢂAcO), 2.43 (s, 3H, SCH ),
3
3
0
(
6
4ꢂCH C]O), 29.7 (N(3 )eCH ), 39.9 (N(1)eCH ), 62.1,
2.70 (s, 3H, N(1)eCH ), 3.67 (ddd, J¼10.0, 4.6, 1.7 Hz, 1H,
3
3
3
3
3
00
8.6, 69.0, 69.5, 70.7, 73.1, 74.2, 75.8, 77.6 (2ꢂC -sp ), 80.1
H-sugar), 3.80 (dd, J¼12.2, 1.7 Hz, 1H, H-6 ), 4.15 (dd,
6
0
0
0
0
00
(
C-1 ), 93.1 (C-5 ), 134.4, 136.1, 136.7, 137.2, 137.4, 139.5,
J¼12.2, 4.6 Hz, 1H, H-6 ), 4.20 (d, J¼9.5 Hz, 1H, H-5),
1
1
1
1
1
1
39.7, 139.9, 140.10, 140.14, 141.4, 141.5, 141.7, 142.0,
42.16, 142.18, 142.2, 142.3, 142.5, 142.6, 142.90, 142.94,
43.1, 144.4, 144.5, 144.6, 145.0, 145.06, 145.11, 145.2,
45.3, 145.35, 145.41, 145.46, 145.48, 145.7, 145.9, 146.0,
46.1, 146.2, 146.6, 147.1, 147.2, 147.3, 153.1, 153.4, 155.2,
56.1, 157.9, 161.9, 162.9, 169.5, 169.8, 170.4, 170.6
4.98 (d, J¼9.5 Hz, 1H, H-5), 5.08 (t, J¼9.3 Hz, 1H, H-sugar),
5.29 (t, J¼9.3 Hz, 1H, H-sugar), 5.35 (t, J¼9.3 Hz, 1H, H-
sugar), 5.59 (s, 1H, H-2), 5.67 (t, J¼9.3 Hz, 1H, H-sugar),
0
13
9.71 (d, J¼9.3 Hz, 1H, NH), 12.77 (br s, 1H, N(3 )eH).
C
NMR (125.77 MHz, CDCl ): d¼13.3 (SCH ), 20.57, 20.64,
3
3
0
0
20.7, 20.8 (4ꢂCH C]O), 39.9 (N(1)eCH ), 62.2 (C-6 ),
3
3
þ
ꢅ
þ
00
(
4ꢂCH C]O). MS (LSIMS) m/z 1277 [MþH] , 720 [C ] .
68.5, 69.1 (C-5), 70.7, 73.1 (C-5 ), 73.5, 74.2 (C-2), 76.0,
00
3
60
3
0
7
8.0 (2ꢂC -sp ), 79.3 (C-1 ), 91.3 (C-5 ), 134.8, 135.8,
6
0
4
.5.8. Compound 10b
1
136.5, 137.6, 138.5, 139.3, 139.8, 140.1, 140.2, 141.35,
141.39, 141.6, 141.97, 142.02, 142.1, 142.20, 142.22, 142.3,
142.49, 142.54, 142.6, 142.9, 144.2, 144.3, 144.4, 144.5,
145.0, 145.15, 145.19, 145.24, 145.3, 145.4, 145.59, 145.64,
145.9, 145.96, 146.01, 146.04, 146.1, 146.2, 146.4, 146.67,
146.69, 147.2, 147.3, 151.6, 153.2, 155.2, 156.6, 159.4,
ꢁ
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.89, 2.00,
3
2
.06, 2.17 (4s, 4ꢂ3H, 4ꢂAcO), 2.54 (s, 3H, SCH ), 2.70 (s, 3H,
3
0
N(1)eCH ), 3.46 (s, 3H, N(3 )eCH ), 3.67 (ddd, J¼10.0, 4.6,
3
3
0
0
1
4
.9 Hz, 1H, H-sugar), 3.84 (dd, J¼12.1, 1.9 Hz, 1H, H-6 ),
0
0
.17 (dd, J¼12.1, 4.7 Hz, 1H, H-6 ), 4.22 (d, J¼9.6 Hz, 1H,
H-5), 4.99 (d, J¼9.6 Hz, 1H, H-5), 5.09 (t, J¼9.2 Hz, 1H,
161.3, 165.1, 169.4, 169.8, 170.3, 170.6 (4ꢂCH C]O). MS
3
þ
ꢅ
þ
H-sugar), 5.31 (t, J¼9.2 Hz, 1H, H-sugar), 5.37 (t, J¼9.2 Hz,
(LSIMS) m/z 1263 [MþH] , 720 [C ] .
6
0
1
9
H, H-sugar), 5.61 (s, 1H, H-2), 5.68 (t, J¼9.2 Hz, 1H, H-sugar),
1
3
.58 (d, J¼9.2 Hz, 1H, NH). C NMR (125.77 MHz, CDCl ):
4.5.11. Compound 12a
1
3
0
ꢁ
d¼20.6, 20.7, 20.8, 22.7 (4ꢂCH C]O), 30.3 (N(3 )eCH ),
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.88, 2.10,
3
3
3
3
7
1
1
1
1
1
1
1
9.8 (N(1)eCH ), 62.3, 68.7, 69.2, 69.3, 70.6, 73.1, 73.5,
3
2.16 (3s, 3ꢂ3H, 3ꢂAcO), 2.46 (s, 3H, SCH ), 2.86 (s, 3H,
3
3
00
0
5.1, 76.1, 77.6 (2ꢂC -sp ), 79.4 (C-1 ), 91.0 (C-5 ), 134.8,
N(1)eCH ), 3.78e3.88 (m, 2H, H-sugar), 4.32 (d, J¼9.8 Hz,
6
0
3
36.0, 136.5, 137.7, 139.3, 139.9, 140.07, 140.13, 140.14,
41.56, 141.61, 141.7, 142.0, 142.1, 142.19, 142.23, 142.3,
42.4, 142.5, 142.6, 142.8, 143.1, 144.3, 144.4, 144.5, 144.6,
44.9, 145.2, 145.26, 145.32, 145.4, 145.65, 145.68, 145.9,
45.98, 146.02, 146.1, 146.19, 146.20, 146.5, 146.9, 147.2,
47.3, 151.9, 153.2, 154.9, 156.8, 157.0, 162.1, 162.8, 169.4,
1H, H-5), 4.95e5.25 (m, 3H, H-5 and 2ꢂH-sugar), 5.63 (s,
1H, H-2), 5.70 (t, J¼9.3 Hz, 1H, H-sugar), 6.09 (dd, J¼7.0,
4.5 Hz, 1H, H-sugar), 10.07 (d, J¼7.1 Hz, 1H, NH), 12.69 (br
ꢅ
þ
0
þ
s, 1H, N(3 )eH). MS (LSIMS) m/z 1191 [MþH] , 720 [C ] .
6
0
4.5.12. Compound 12b
1
ꢁ
69.8, 170.3, 170.6 (4ꢂCH C]O). MS (LSIMS) m/z 1277
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼2.13,
3
3
þ
ꢅ
þ
[
MþH] , 720 [C ] .
2.16, 2.18 (3s, 3ꢂ3H, 3ꢂAcO), 2.49 (s, 3H, SCH ), 2.91 (s,
6
0
3
3
H, N(1)eCH ), 3.96 (dd, J¼13.4, 2.1 Hz, 1H, H-sugar),
3
4
.5.9. Compound 11a
1
4.08e4.13 (m, 1H, H-sugar), 4.32 (d, J¼9.7 Hz, 1H, H-5),
4.73e4.79 (m, 2H, H-sugar), 4.91 (d, J¼9.7 Hz, 1H, H-5),
5.27e5.29 (m, 1H, H-sugar), 5.59 (s, 1H, H-2), 5.88 (dd,
J¼9.7, 1.7 Hz, 1H, H-sugar), 9.81 (d, J¼9.8 Hz, 1H, NH),
ꢁ
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.93, 1.99,
3
2
.05, 2.12 (4s, 4ꢂ3H, 4ꢂAcO), 2.46 (s, 3H, SCH ), 2.77 (s, 3H,
3
N(1)eCH ), 3.79 (ddd, J¼9.8, 4.7, 2.3 Hz, 1H, H-sugar), 4.17
3
00
0
13
(
4
dd, J¼12.2, 2.3 Hz, 1H, H-6 ), 4.26 (d, J¼9.6 Hz, 1H, H-5),
12.03 (br s, 1H, N(3 )eH). C NMR (125.77 MHz, CDCl ):
3
0
0
.30 (dd, J¼12.2, 4.7 Hz, 1H, H-6 ), 4.99 (d, J¼9.6 Hz, 1H,
d¼13.1 (SCH ), 20.9, 21.07, 21.10, 22.7 (4ꢂCH C]O),
3
3
H-5), 5.16e5.25 (m, 1H, H-sugar), 5.29e5.36 (m, 2H, 2ꢂH-
13
40.1 (N(1)eCH ), 64.7, 66.2, 67.0, 68.8, 69.0, 69.7, 74.6,
3
3
0
sugar), 5.52 (s, 1H, H-2), 5.73e5.79 (m, 1H, H-sugar), 9.36
0
75.6, 76.3, 78.0 (2ꢂC -sp ), 91.1 (C-5 ), 134.7, 135.7,
6
0
(
d, J¼10.8 Hz, 1H, NH), 12.86 (br s, 1H, N(3 )eH). C NMR
136.0, 136.1, 136.2, 138.78, 138.82, 139.5, 139.6, 139.8,
140.1, 140.2, 141.0, 141.3, 141.6, 141.8, 141.96, 141.98,
142.0, 142.1, 142.2, 142.3, 142.4, 142.51, 142.53, 142.7,
142.9, 143.0, 144.3, 144.4, 144.7, 145.09, 145.14, 145.16,
145.19, 145.25, 145.29, 145.33, 145.5, 145.6, 145.8, 145.98,
145.99, 146.0, 146.05, 146.12, 146.3, 146.5, 147.3, 152.96,
153.01, 154.9, 155.9, 159.0, 161.6, 165.0, 167.8, 168.4,
(
(
75.47 MHz, CDCl ): d¼13.4 (SCH ), 20.5, 20.6, 20.8, 20.3
3
3
00
4ꢂCH C]O), 40.0 (N(1)eCH ), 62.2 (C-6 ), 68.6, 69.4 (C-
3
3
0
0
3
5
7
1
1
), 70.7, 73.2 (C-5 ), 74.1, 74.8 (C-2), 76.2, 76.3 (2ꢂC -sp ),
6
0
0
0
0
9.9 (C-1 ), 93.2 (C-5 ), 135.9, 136.7, 137.0, 139.6, 140.1,
40.2, 141.48, 141.54, 141.7, 141.8, 141.97, 142.01, 142.1,
42.2, 142.3, 142.5, 142.56, 142.64, 142.9, 144.3, 144.4,

4436
C.I.C. Jord ~a o et al. / Tetrahedron 64 (2008) 4427e4437
þ
1
7
69.6, 169.7 (4ꢂCH C]O). MS (LSIMS) m/z 1191 [MþH] ,
solution of 5% Na S O (2ꢂ50 mL). The organic phase was
2 2 3
3
ꢅ
20 [C ] .
þ
concentrated and purified by flash chromatography (silica
gel) using toluene as the eluent. Compound 16 was crystallised
6
0
0
0
4
.5.13. 2 ,3 -O-Isopropylideneuridine 14
PTSA (0.016 mg, 0.1 equiv) was added to a solution of uri-
dine (200 mg, 0.82 mmol) in acetone (6 mL) and the resulting
mixture was stirred at room temperature for 48 h. One drop of
NEt was added to the reaction mixture and then it was con-
from CHCl /MeOH giving brown crystals (17 mg, 17% yield).
3
ꢁ
1
Mp >300 C. H NMR (300.13 MHz, CDCl ): d¼1.36, 1.57
3
(2s, 2ꢂ3H, 2ꢂCH ), 3.44 (s, 2H, malonate CH ), 3.75 (s,
3
2
0
3H, OCH ), 3.76 (dd, J¼11.8, 4.5 Hz, 1H, H-5 ), 3.87 (dd,
3
0
0
J¼11.8, 6.0 Hz, 1H, H-5 ), 4.52e4.57 (m, 1H, H-4 ), 4.84
3
0
centrated. Compound 14 was purified by preparative TLC (sil-
ica gel) using a 95:5 mixture of CHCl /MeOH as the eluent.
(dd, J¼6.5, 3.7 Hz, 1H, H-3 ), 4.99 (dd, J¼6.5, 2.0 Hz, 1H,
0
0
H-2 ), 5.67 (d, J¼2.0 Hz, 1H, H-1 ), 5.78 (d, J¼8.0 Hz, 1H,
3
1
3
Evaporation of the solvent afforded a white solid (173 mg,
7
H-5), 7.34 (d, J¼8.0 Hz, 1H, H-6), 8.80 (br s, 1H, NH).
C
ꢁ
1
4% yield) with mp 146e147 C. H NMR (300.13 MHz,
NMR (75.47 MHz, CDCl ): d¼27.1, 25.2 (2ꢂCH ), 54.2
3
3
0
3
(OCH ), 66.3 (C-5 ), 71.23 (C -sp ), 81.5 (C-3 ), 84.4
0
CDCl /CD OD): d¼1.39, 1.59 (2s, 2ꢂ3H, 2ꢂCH ), 3.76
3
3
3
3
60
0
0
0
0
(
1
dd, J¼12.0, 3.5 Hz, 1H, H-5 ), 3.87 (dd, J¼12.0, 2.5 Hz,
(C-2 ), 85.1 (C-4 ), 95.6 (C-1 ), 102.9 (C-5), 114.7
(C(CH ) ), 142.2 (C-6), 142.4, 143.0, 143.9, 144.8, 144.9,
145.2, 145.3, 149.7 (C-2), 162.6 (C-4), 163.1, 163.9
(2ꢂmalonate C]O). MS (MALDI-TOF) m/z 1102 [M] .
0
0
H, H-5 ), 4.29 (q, J¼2.5 Hz, 1H, H-4 ), 4.88e4.93 (m, 2H,
13
3
2
0
0
H-2 and H-3 ), 5.71 (d, J¼8.1 Hz, 1H, H-5), 5.75 (d,
ꢅ
þ
0
J¼2.3 Hz, 1H, H-1 ), 7.60 (d, J¼8.1 Hz, 1H, H-6).
C
NMR (75.47 MHz, CDCl /CD OD): d¼25.1, 27.1 (2ꢂCH ),
3
3
3
0
0
0
0
0
6
1
1
2.3 (C-5 ), 80.3 (C-3 ), 83.9 (C-2 ), 86.8 (C-4 ), 95.0 (C-1 ),
02.4 (C-5), 114.6 (C(CH ) ), 142.6 (C-6), 150.42 (C-2),
4.5.16. Fullereneeuridine conjugate 17
To a solution of dyad 16 (15 mg) in CHCl (3 mL) was
3
2
3
þ
þ
63.7 (C-4). MS (ESI) m/z 285 [MþH] , 307 [MþNa] . Ele-
added a 9:1 mixture of CF CO H/H O (5 mL) and the reaction
3
2
2
mental analysis (%) calcd for C H N O : C 50.70, H 5.67, N
1
mixture was stirred for 14 h at room temperature. It was then
neutralised with a saturated aqueous solution of Na CO and
2 16 2 6
9
4
2
.85; found C 50.41, H 5.79, N 9.93.
2
3
dyad 17 was extracted with a mixture of CHCl /MeOH (3ꢂ
3
.5.14. Methyl uridinyl malonate 15
30 mL). The organic layer was dried (Na SO ), concentrated,
2
4
A solution of methyl 3-chloro-3-oxopropanoate (0.034 mL,
equiv) diluted in CH Cl was added dropwise to an ice
cooled solution of compound 14 (50 mg, 0.18 mmol) and an-
hydrous NEt (0.097 mL, 0.7 mmol) in CH Cl (7 mL). The
and compound 17 was precipitated by the addition of MeOH
ꢁ
2
2
affording a brown solid (14 mg, 96% yield). Mp >300 C.
1
H NMR (300.13 MHz, DMSO-d ): d¼4.05 (s, 3H, OCH ),
6
3
0
0
0
3
2
2
4.19 (m, 2H, H-5 ), 4.66e4.73 (m, 2H, H-2 and H-3 ),
0
ice bath was then removed and the reaction mixture was stirred
at room temperature for 3 h. It was then washed with an aque-
ous solution of 0.5% HCl (2 ꢂ 30 mL) and with a saturated
5.45e5.49 (m, 1H, H-4 ), 5.63 (d, J¼8.3 Hz, 1H, H-5), 5.82
0
(d, J¼5.7 Hz, 1H, H-1 ), 7.72 (d, J¼8.3 Hz, 1H, H-6), 11.39
þ
þ
(br s, 1H, NH). MS (ESI) m/z 1063 [MþH] , 1085 [MþNa] .
aqueous solution of NaHCO (2 ꢂ 30 mL). The organic phase
3
was dried (Na SO ) and the solvent was evaporated under vac-
2
4
Acknowledgements
uum. Compound 15 was purified by TLC (silica gel) using an
:2 mixture of ethyl acetate/petroleum ether as the eluent.
Evaporation of the solvent afforded a white solid (53 mg,
8
Thanks are due to the Funda c¸ ~a o para a Ci eˆ ncia e a Tecnolo-
gia (FCT, Portugal) and FEDER for funding the Organic
Chemistry Research Unit and the project POCI/QUI/58515/
2004 and also for funding towards the purchase of the sin-
gle-crystal diffractometer. A.S.F.F. and R.F.E. also thank
FCT for their doctoral (SFRH/BD/32219/2006) and post-doc-
toral (SFRH/BPD/24213/2005) grants, respectively.
ꢁ
1
7
7% yield) with mp 128e129 C. H NMR (300.13 MHz,
CDCl ): d¼1.36, 1.57 (2s, 2ꢂ3H, 2ꢂCH ), 3.44 (s, 2H, mal-
3
3
0
onate CH ), 3.75 (s, 3H, OCH ), 4.34e4.35 (m, 3H, H-4 and
2
3
0
0
2
2
ꢂH-5 ), 4.84 (dd, J¼6.5, 3.7 Hz, 1H, H-3 ), 4.99 (dd, J¼6.5,
0
0
.0 Hz, 1H, H-2 ), 5.67 (d, J¼2.0 Hz, 1H, H-1 ), 5.76 (d,
1
3
J¼8.4 Hz, 1H, H-5), 7.30 (d, J¼8.4 Hz, 1H, H-6). C NMR
75.47 MHz, CDCl ): d¼27.0, 25.18 (2CH ), 41.1 (malonate
(
3
3
References and notes
0
0
0
CH ), 52.7 (OCH ), 64.8 (C-5 ), 80.8 (C-3 ), 84.4 (C-2 ),
2
3
0 0
5.0 (C-4 ), 94.6 (C-1 ), 102.6 (C-5), 114.6 (C(CH ) ), 142.3
3 2
8
1. Recent reviews: (a) Bendikov, M.; Wudl, F.; Perepichka, D. F. Chem. Rev.
ꢀ
(
C-6), 149.9 (C-2), 163.4 (C-4), 165.9, 166.8 (2ꢂmalonate
2004, 104, 4891e4945; (b) S a´ nchez, L.; Herranz, A.; Mart ´ı n, N. J. Mater.
þ
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2
(
C 50.05, H 5.36, N 7.26.
%) calcd for C H N O : C 50.00, H 5.25, N 7.24; found
16 20 2 9
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2
4
.5.15. Fullereneeuridine conjugate 16
To a solution of malonate 15 (35 mg, 0.091 mmol) and C60
98 mg, 1.5 equiv) in anhydrous toluene (50 mL) were added
1
999, 663e669; (c) Tagmatarchis, N.; Shinohara, H. Mini-Rev. Med.
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(
2
iodine (34 mg, 1.5 equiv) and DBU (0.042 mL, 3 equiv). The
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a nitrogen atmosphere. It was then washed with an aqueous
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8
9
9
1
. For the H NMR discussion, protons H-5 were indicated as H-5a (the one
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1
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