Acetylation of α- And β-cyclodextrines

Article abstract of DOI:10.1134/S1070428011020205

Applying acetyl chloride and versatile bases and solvents per- and regioacetylated derivatives of α- and β-cyclodextrines were prepared. Conditions were established for performing regiodirected acetylation of the primary hydroxy groups of α- and β-cyclodextrines in the presence of free secondary hydroxy groups.

Full text of DOI:10.1134/S1070428011020205

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 2, pp. 284289. Pleiades Publishing, Ltd., 2011.
Original Russian Text  M.K. Grachev, A.V. Edunov, G.I. Kurochkina, A.V. Popkov, I.I. Levina, E.E. Nifant’ev, 2011, published in Zhurnal Organicheskoi
Khimii, 2011, Vol. 47, No. 2, pp. 290295.
Acetylation of α- and β-Cyclodextrines
M. K. Grachev, A. V. Edunov, G. I. Kurochkina, A. V. Popkov,
I. I. Levina, and E. E. Nifant’ev
Moscow State Pedagogical University, Moscow, 119021 Russia
e-mail: chemdept@mail.ru
Received March 22, 2010
Abstract—Applying acetyl chloride and versatile bases and solvents per- and regioacetylated derivatives of α-
and β-cyclodextrines were prepared. Conditions were established for performing regiodirected acetylation of the
primary hydroxy groups of α- and β-cyclodextrines in the presence of free secondary hydroxy groups.
DOI: 10.1134/S1070428011020205
Cyclodextrines are complex natural cyclic oligo-
saccharides whose molecules are built of regularly
placed glucopyranose units. The most wide spread
cyclodextrines, the so-called α-, β-, and γ-cyclodextrines,
containing six, seven, and eight glucopyranose units
respectively, are presently extensively used in the fine
organic synthesis and for solution of the modern applies
problems (see, e.g., [1]). The molecules of cyclodextrines
possess relatively rigid toroid structure, where on one
side (on the wide part of the molecule) the secondary
hydroxy groups are located at the positions C2 and C3
of the glucoside units, and on the other (narrow) side in
the positions C6 the primary hydroxy groups are present.
An important structural feature of the cyclodextrines is
the formation of strong intramolecular hydrogen bonds
between the secondary hydroxy groups of the contiguous
glucoside fragments that ensure the rigidity of the
cyclodextrine skeleton.Although the OH groups favor the
enhanced solubility of carbohydrates in water, the most
widely spread and available β-cyclodextrine unexpectedly
proved to be spairingly soluble in water (18 g l−1), while
α- and γ-cyclodextrines were much more soluble [2]. The
most practically important property of the cyclodextrines
is the presence of internal hydrophobic cavity providing
them with a possibility to form inclusion complexes of
“guest–host” type with various organic and inorganic
molecules and ions.
modification of their molecules [3]. However the
regioselective functionalization of cyclodextrines is an
experimentally difficult problem due to the presence in
their molecules of the three mentioned types of hydroxy
groups distinct in the character. Initially the chemical
modification of the cyclodextrines consisted in the
total or random substitution of the hydroxy groups [4],
later the attention was directed to the regioselectively
substituted cyclodextrines [3]. Although the synthetic
methods were well developed for monosaccharides and
linear oligosaccharides the simple application of these
procedures to the cyclodextrines proved to be impossible
due to the large number of spatially close hydroxy groups
of similar reactivity and also because of the presence
of the inner cavity prone to the formation of inclusion
complexes with the reagents leading consequently to the
changes in the “common” reaction pathway (see, e.g., [5,
6]). Therefore although a large number of publications
describes the synthesis of cyclodextrine derivatives, the
general possibilities and laws of their functionalization are
limitedly investigated even with respect to the acylation
reaction. The effect on the modification of cyclodextrines
of such important factors like the nature of the solvent,
molar ratio of the reagents, and the reaction temperature
is poorly understood.
The goal of this study was the investigatiob of
acetylation of the available α- and β-cyclodextrines
significantly differing in the size of the internal cavity
(174 and 262 Å3 respectively) [2]. It is known that the
acetylation, methylation [7], and hydroxypropylation [8]
Many properties of cyclodextrines, e.g., the solubility
in water and organic solvents, the ability to form
inclusion compounds, can be modified by a selective
284

ACETYLATION OF α- AND β-CYCLODEXTRINES
285
results in a significant increase in the solubility in water
and in organic solvents. Usually the increased solubility
in water is attained by introducing into the initial molecule
of a small number of functional groups, whereas the high
solubility in organic solvents requires the introduction of
a large number of such groups. It is also important that the
modification of the cyclodextrines should in the general
sense result in the increased volume of the inner cavity
leading to the higher capability to form stable inclusion
complexes, in particular, with “guests” interesting, e.g.,
from the pharmacological viewpoint [9].1 Acetylated
cyclodextrine derivatives are commonly obtained by
treating with acetic anhydride in pyridine. This proce-
dure is not regioselective and is used as a rule when it
is necessary to acetylate all free hydroxy groups of the
cyclodextrines and their derivatives [10–13]. It should
be additionally taken into account that the cyclodextrine
can exhibit unususl (supramolecular) properties, for
instance, at the phosphorylation with the phosphorous
acid chloride [5] and at the acylation with valeryl and
palmitoyl chlorides [6].
The acetylation by method b was carried out in DMF
in the presence of triethylamine, and in both cases the
acetylating reagent was taken in a significant molar excess
(see EXPERIMENTAL).
The acetylated α- and β-cyclodextrines III and IV
were isolated in 90 (a) and 78% (b) yields. The complete-
ness of the acetylation was estimated by the analysis of
the 1H and 13C NMR spectra. In the 1H NMR spectra three
signals of the acetyl protons appear of the groups attached
to C2, C3, and C6 in the region 2.09–2.34 ppm with the
corresponding integral ratio to the protons of the cyclo-
dextrine frame. The absence of the free hydroxy groups
(i.e., the completeness of the acetylation) was additionally
proved by heating the solution to 60°C at the registering
the NMR spectra. Therewith no shift was observed of the
signals of the OH protons (in the case of their presence).
In the 13C NMR spectra the signals of carbon atoms C2,
C3 , and C6 [12, 13, 16] linked to the acetyl groups were
shifted downfield with respect to the position of these
atoms in the initial α- and β-cyclodextrines. Besides three
signals were observed in the region 20.5–21.1 ppm and
tree peaks in the region 168.2–170.7 ppm belonging to the
methyl and carbonyl carbon atoms of the acetyl groups
respectively (see EXPERIMENTAL). It is presumable
that the upfield proton signals at 2.09 ppm and carbon
signals at 20.5 and 168.2 ppm belong to the acetyl groups
linked to C6. The additional proof of this assignment was
obtained by the analysis of the 1H and 13C NMR spectra
of the partially acetylated α- and β-cyclodextrines.
We investigated the acetylation of secondary hydroxy
groups of silyl derivatives of α- and β-cyclodextrines
with acetyl chloride in the presence of bases and solvents
differing in the nature. The subsequent removal of
the silyl protection provided the cyclodextrine acetyl
derivatives possessing free primary hydroxy groups [14].
It turned out that the degree of the acetylation essentially
depends on the nature of the base and the solvent. Taking
into consideration these data, it is presumable that the
application of the acetyl chloride in combination with
bases of various nature as acylation activators and
acceptors of the hydrogen chloride would result in
the regioselective substitution of prevailingly primary
hydroxy groups. The publications on the acylation of the
hydroxy groups in the β-cyclodextrine with acid chlorides
concerned the asids with longer chain than acetic acid,
valeryl chloride [6] etc. [6, 15].
Regioselective acetylation of cyclodextrines I and
II was performed with acetyl chloride with amines of
various nature (C = pyridine, triethylamine, N,N-dimeth-
ylaniline). As solvents dimethylformamide and pyridine
were used for the initial cyclodextrines2 were soluble in
these solvents (pyridine was simultaneously the hydrogen
chloride acceptor). For the sake of comparison all experi-
ments were carried out under the same conditions: To
a solution of the cyclodextrine at 0°C the acetyl chloride
solution was added, the stirring was continued for 24 h
at 20°C, and the acetylation products were isolated, as
described in EXPERIMENTAL. In order to estimate the
regioselectivity of the acetylation, the acetyl chloride was
taken in molar deficit [m = 5 (I), 6 (II)] with respect to
the overall amount of the hydroxy groups (18 and 21 for
α- and β- cyclodextrines respectively).
The exhaustive acetylation of α- and β-cyclodextrines
I and II was performed by acetic anhydride (method
a) and by acetyl chloride (method b) (Scheme 1). The
acetylation by method a was carried out in DMF in
the presence of sodium hydrogen carbonate providing
a possibility to acetylate under considerably milder
conditions than in the mentioned procedures [10–13].
___________
___________
1 It is important since in the majority of the known publications the
labile inclusion complexes are mentioned, namely, existing in the
solution in equilibrium with the free dissolved reagent.
2 α-Cyclodextrine is spairingly soluble in pyridine, but in the course
of the acetylation the reaction mixture becomes homogeneous.
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GRACHEV et al.
286
Scheme 1.
HO
O
O
OH
6
3
4
O
HO
5
2
OH
O
1
HO
OH
1_3
OH
OH
O
O
n
OH
HO
OH
OH
OH
O
OH
OH
n
O
OH
I, II
O
OH
OH
O
OAc
O
OH
n
(a) Ac2O, DMF, NaHCO3
(b) AcCl, DMF, Et3N
HO
O
OH
I, II
OAc
OAc
n
III, IV
n = 6 (I, III), 7 (II, IV).
The average acetylation degree (x + y) was estimated
from H NMR spectra by the ratio of the integral in-
VIII the prolonged keeping of the reaction mixture did
not result in a higher acetylation degree, only in the ac-
cumulation of side products (Scheme 2).
1
tensity of the proton signals of the acetyl groups in the
region 1.85–2.10 ppm to the signals of the protons of
the cyclodextrine frame in the region 3.80–4.95 ppm.
For α-cyclodextrine x + y ≤ 3 (compound V, methods
a–c), and in DMF in the presence of pyridine x + y = 2
(compound VI) (Table 1), whereas for β-cyclodextrine
in pyridine and DMF in the presence of pyridine the
acetylation degree was the maximum possible (x + y =
6, compound VII, methods a, b), and in two other cases
x + y = 3 (compound VIII, methods a, b) (Table 2). When
the acetylation was incomplete giving compounds V, VI,
In the spectra of all synthesized compounds V–VIII
the proton signals of the acetyl groups in contrast to the
completely acetylated derivatives III, IV appeared as one
broad signal in the region 1.85–2.10 ppm thus preventing
the estimation from the 1H NMR spectra of the regiose-
lectivity of the acetylationandя (x and/or y).
13
The C NMR spectra turned out to be more infor-
mative for the evaluation of the regioselectivity of the
acetylation. In the spectra of compounds V, VII signals are
present of atoms C6 free of acetyl groups at 61.3 (V) and
60.8 ppm (VII), and also a characteristic [16] downfield
signal of atoms C6'3 linked to acetyl groups at 63.9 ppm.
Analogous conclusion follows from the analysis of the
signals of the carbonyl carbon atoms: In the spectra of
compounds V, VII acetylated only at the atom C6 instead
of three signals in the spectra of compounds III (168.4,
169.9, 170.7 ppm), IV (168.2, 169.8, 170.5 ppm) ap-
pears a single signal at 170.5 ppm. These data permit
Scheme 2.
HO
_
OAc x
OH n
n
x
mAcCl, B
_
.
B HCl
_
y OH
OH
I, II
OAc y
OH
2n
n
V_VIII
a conclusion that compounds V, VII are cyclodextrine
___________
n = 6: x = 3, y = 0 (V);
x = 1, y = 1 (VI);
n = 7: x = 6, y = 0 (VII);
3 Analogous shift confirming the substitution at the atom C6 is ob-
served for the atom C5' adjacent to the atom C6’(see EXPERIMEN-
TAL).
x = 2, y = 1 (VIII).
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ACETYLATION OF α- AND β-CYCLODEXTRINES
287
Table 1. Acetylation of α-cyclodextrine (I) with acetyl chloride
derivatives acetylated only at the primary hydroxy groups
(at the atom C6).
Mean degree
of substitution Reaction product,
(substitution yield, % (method)
In compounds VI, VIII the secondary hydroxy groups
at the atom C2(3) are also acetylated. In the 13C NMR
spectra of these compounds additional signals of methyl
groups at 20.7 (VI) and 21.1 ppm (VIII) and of carbonyl
groups at 169.9 (VI) and 169.8 ppm (VIII) are present
in the approximate integral ratio to the intensity of the
corresponding acetyl groups in the position C6 ~1:1 for
compound VI and 1:2 for compound VIII.4 The data
obtained are insufficient for the assignment of the acetyl
groups to atoms C2 and/or C3.
Solvent
C
position)
Py
Py
Et3N
Py
3 (C6)
3 (C6)
V, 67(c
V, 52(a)
VI, 70
DMF
DMF
DMF
2 (C2(3),6
)
Me2NPh
3 (C2(3),6
)
V, 52(b)
Table 2. Acetylation of β-cyclodextrine (II) with acetyl chloride
Mean degree
of substitution Reaction product,
(substitution yield, % (method)
Formerly we performed selective acylation [6, 17] and
phosphorylation [18] of primary hydroxy groups in the
presence of secondary ones using a sterically hindered
diisopropylethylamine as was suggested in [19]. In this
study we also tested the possibility of the application of
the diisopropylethylamine for the regioselective acetyla-
tion of α- and β- cyclodextrines. However the acetylation
products contained in the internal cavity of the cyclodex-
trine a molecule of the diisopropylethylamine5 which we
failed to remove under the conditions of the synthesis and
isolation of the product, and the acetylation proceeded
with an appreciably slower rate (x + y ≤ 1).
Solvent
C
position)
Py
Py
Et3N
Py
6 (C6)
3 (C2(3),6
6 (C6)
VII, 81(b)
VIII, 59(a)
VII, 75(a)
VIII, 55(b)
DMF
DMF
DMF
)
)
Me2NPh
3 (C2(3),6
hydrogen carbonate and 0.88 g (8.64 mmol) of acetic
anhydride, the mixture was stirred and heated for 5 h
at 80°C, then kept for 24 h at 20°C, the solution was
filtered, concentrated to 1 ml, diluted with 10 ml of ethyl
ether, the separated precipitate was filtered off, washed
with ether (2 × 5 ml), dried, ground with 5 ml of water,
filtered off, washed with water (3 × 5 ml), and dried in
a vacuum (1 mm Hg) for 4 h at 60°C. Yield 0.64 g (90%),
mp 238–239°C (239°C [20]), Rf 0.72 (A). 1H NMR spec-
trum (CDCl3), δ, ppm: 2.09 s [18H, CH3C(O)OC6], 2.17 s
and 2.33 s [36H, CH3C(O)OC2,3], 3.10–5.80 m 42H,
C1H–C5H, C6H2]. 13C NMR spectrum (CDCl3), δ, ppm:
20.5, 20.9, 21.0 [C(O)CH3], 63.0 (C6), 69.6, 70.6, 72.3
(C2,3,5), 83.3 (C4), 99.8 (C1), 168.4, 169.9, 170.7 (C=O).
Found, %: C 50.08; H 5.63. C72H96O48. Calculated, %:
C 50.00; H 5.59.
b. To a solution of 0.40 g (0.411 mmol) of α-cyclo-
dextrine and 1.37 g (13.6 mmol) of triethylamine in 10 ml
of DMF at stirring was added within 20 min at 0°C a solu-
tion of 0.97 g (12.3 mmol) of acetyl chloride in 5 ml of
DMF, the mixture was stirred and left standing for 24 h
at 20OC, the solution was filtered, concentrated to 1 ml,
diluted with 10 ml of ethyl ether, the separated precipitate
was filtered off, washed with ether (2 × 5 ml), dried, dis-
solved in 3 ml of methanol and poured into 30 ml of ether,
stirred, the separated precipitate was filtered off, washed
with ether (2×5 ml), and dried in a vacuum (1 mm Hg) for
4 h at 60°C. Yield 0.55 g (78%), mp 237–239°C, Rf 0.72
Thus with the use of acetyl chloride and bases and
solvents of various nature we developed new routes to
the exhaustive and regioselective acetylation of α- and
β-cyclodextrines. With the use of 13C NMR spectroscopy
the assignment was performed of the acetyl groups to
atoms C6 and C2(3)
.
EXPERIMENTAL
1H and 13C NMR spectra were registered on a spec-
trometer Jeol ECX400 at operating frequencies 400 and
100.53 MHz respectively, external reference TMS. Tlc
was performed on aluminum plates with a fixed layer of
silica gel (Silufol-254), eluents chloroform–methanol,
1 : 1 (A), hexane–acetone, 3 : 2 (B), benzene–DMF, 7 : 1
(C), development in iodine vapor. α- and β-Cyclodextrines
were purchased from MerCk (BRD) and were thoroughly
dried before use.
Per(2,3,6-tri-O-acetyl)-α-cyclodextrine (III). a. To
a solution of 0.40 g (0.411 mmol) of α-cyclodextrine in
10 ml of DMF was added 1.45 g (17.3 mmol) of sodium
___________
4 To perform the integration of the mentioned signal the 13C NMR
spectra of compounds VI, VIII were registered in the pulse Fourier-
transform mode with a large delay between the pulses (8 s).
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GRACHEV et al.
288
(A). 1H and 13C NMR spectra coincide with the spectra
described under method a.
c. Compound V was obtained similarly to meth-
od a from a dispersion of 0.40 g (0.411 mmol) of
α-cyclodextrine in 10 ml of pyridine and 0.16 g
(2.06 mmol) of acetyl chloride in 5 ml of pyridine. Yield
0.30 g (67%), mp 201–202°C (decomp.), Rf 0.59 (C). 1H
and 13C NMR spectra coincide with the spectra described
under method a.
Per(2,3,6-tri-O-acetyl)-β-cyclodextrine (IV) was
similarly obtained. a. From 0.40 g (0.352 mmol) of
β-cyclodextrine in 10 ml of DMF, 1.45 g (17.3 mmol)
of sodium hydrogen carbonate and 0.88 g (8.64 mmol)
of acetic anhydride. Yield 0.64 g (90%), mp 195–197°C
(198–200°C [10], 195°C [20]), Rf 0.15 (B) (0.14 [10]).
1H NMR spectrum (CDCl3), δ, ppm: 2.09 s [21H,
CH3C(O)OC6], 2.16 s and 2.34 s [42H, CH3C(O)OC2,3],
3.10–5.85 m [49H, C1H–C5H, C6H2]. 13C NMR spec-
trum (CDCl3), δ, ppm: 20.5, 20.9, 21.1 [C(O)CH3], 62.7
(C6), 69.7, 70.3, 72.6 (C2,3,5), 83.2 (C4), 100.1 (C1),
168.2, 169.8, 170.5 (C=O). Found, %: C 50.06; H 5.62.
C84H112O56. Calculated, %: C 50.00; H 5.59.
Compounds VI–VIII were obtained similarly to com-
pound III by method b.
2(3),6-Di-O-acetyl-α-cyclodextrine (VI) was ob-
tained from 0.40 g (0.411 mmol) of α-cyclodextrine,
0.18 g (2.26 mmol) of pyridine in 10 ml of DMF, and
0.16 g (2.06 mmol) of acetyl chloride in 5 ml of DMF.
Yield 0.30 g (70%), mp 193–195°C (decomp.), Rf 0.57
(C). 1H NMR spectrum (Py-d5), δ, ppm: 1.85–2.10 br.s
[6H, CH3C(O)OC2(3),6], 3.80–4.95 m (36H, C2H–C5H,
C6H2), 5.24–5.45 br.s (16H, C6OH, C2OH, C3OH),
5.48–5.56 m (6H, C1H). 13C NMR spectrum (Py-d5), δ,
ppm: 20.5, 20.7 [C(O)CH3], 60.8 (C6), 63.6 (C6’), 69.8
(C5’), 73.7, 73.9, 74.8 (C2,3,5), 82.9 (C4), 102.8 (C1), 169.9,
170.5 (C=O). Found, %: C 45.53; H 6.17. C40H64O32.
Calculated, %: C 45.46; H 6.10.
b. From 0.40 g (0.352 mmol) of β-cyclodextrine and
1.37 g (13.6 mmol) of triethylamine in 10 ml of DMF and
0.97 g (12.3 mmol) of acetyl chloride in 5 ml of DMF.
Yield 0.55 g (78%), mp 195–197°C, Rf 0.15 (B). 1H and
13C NMR spectra coincide with the spectra described
under method a.
[Tri(6-O-acetyl)-α-cyclodextrine] (V). a. To a so-
lution of 0.40 g (0.411 mmol) of α-cyclodextrine and
0.23 g (2.26 mmol) of triethylamine in 10 ml of DMF
at stirring was added within 20 min at 0°C a solution of
0.16 g (2.06 mmol) of acetyl chloride in 5 ml of DMF, the
mixture was stirred and left standing for 24 h at 20°C, the
solution was filtered, concentrated to 1 ml, diluted with
10 ml of acetone, the separated precipitate was filtered
off, washed with acetone (2 × 5 ml), dried, ground with
5 ml of chloroform, filtered off, washed with chloroform
(2 × 5 ml), and dried in a vacuum (1 mm Hg) for 4 h at
60°C. Yield 0.23 g (52%), mp 201–202°C (decomp.),
Rf 0.59 (C). 1H NMR spectrum (Py-d5), δ, ppm: 1.85–2.10
br.s [9H, CH3C(O)OC6], 3.80–4.95 m (36H, C2H–C5H,
C6H2), 5.25–5.46 br.s (15H, C6OH, C2OH, C3OH), 5.48–
5.55 m (6H, C1H). 13C NMR spectrum (Py-d5), δ, ppm:
20.5 [C(O)CH3], 61.3 (C6), 63.9 (C6’), 70.3 (C5’), 73.6,
73.8, 74.7 (C2,3,5), 82.9 (C4), 103.5 (C1), 170.5 (C=O).
Found, %: C 45.97; H 6.15. C42H66O33. Calculated, %:
C 45.90; H 6.05.
Hexa(6-O-acetyl)-β-cyclodextrine (VII). a. Com-
pound VII was obtained from 0.40 g (0.352 mmol)
of β-cyclodextrine, 0.18 g (2.33 mmol) of pyridine
in 10 ml of DMF, and 0.16 g (2.06 mmol) of acetyl
chloride in 5 ml of DMF. Yield 0.37 g (75%), mp
1
171–173°C (decomp.), Rf 0.73 (C). H NMR spectrum
(Py-d5), δ, ppm: 1.85–2.10 br.s [18H, CH3C(O)OC6],
3.80–4.95 m (42H, C2H–C5H, C6H2), 5.26–5.47 br.s
(15H, C6OH, C2OH, C3OH), 5.50–5.58 m (7H, C1H).
13C NMR spectrum (Py-d5), δ, ppm: 20.5 [C(O)CH3],
60.8 (C6), 63.9 (C6’), 70.4 (C5’), 73.6, 73.8, 74.3 (C2,3,5),
83.3 (C4), 103.6 (C1), 170.5 (C=O). Found, %: C 46.82;
H 6.00. C54H82O41. Calculated, %: C 46.75; H 5.96.
b. Compound VII was obtained from 0.40 g (0.35
mmol) of β-cyclodextrine in 10 ml of pyridine and
0.16 g (2.06 mmol) of acetyl chloride in 5 ml of
pyridine. Yield 0.40 g (81%), mp 171–173°C (de-
1
comp.), Rf 0.73 (C). H and 13C NMR spectra co-
incide with the spectra described under method a.
b. Compound V was obtained similarly to method a
from 0.40 g (0.411 mmol) of α-cyclodextrinea, 0.28 g
(2.26 mmol) of N,N-dimethylaniline in 10 ml of DMF,
and 0.16 g (2.06 mmol) acetyl chloride in 5 ml of DMF.
Yield 0.23 g (52%), mp 201–202°C (decomp.), Rf 0.59
(C). 1H and 13C NMR spectra coincide with the spectra
described under method a.
2(3),6,6-Tri-O-acetyl-β-cyclodextrine (VIII). a.
Compound VIII was obtained from 0.40 g (0.352 mmol)
of β-cyclo-dextrine, 0.28 g (2.33 mmol) of triethylamine
in 10 ml DMF, and 0.16 g (2.06 mmol) of acetyl chlo-
ride in 5 ml DMF. Yield 0.26 g (59%), mp 167–168°C
1
(decomp.), Rf 0.70 (C). H NMR spectrum (Py-d5), δ,
ppm: 1.85–2.10 br.c [9H, CH3C(O)OC2(3),6], 3.80–4.95 m
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ACETYLATION OF α- AND β-CYCLODEXTRINES
289
(42H, C2H–C5H, C6H2), 5.25–5.48 br.s (18H, C6OH,
C2OH, C3OH), 5.49–5.57 m (7H, C1H). 13C NMR spec-
trum (Py-d5), δ, ppm: 20.5, 21.1 [C(O)CH3], 61.2 (C6),
64.2 (C6’), 70.5 (C5’) 73.5, 73.7, 74.4 (C2,3,5), 83.1 (C4),
103.7 (C1), 169.8, 170.6 (C=O). Found, %: C 45.79;
H 6.11. C48H76O38. Calculated, %: C 45.72; H 6.07.
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Nauk, Ser. Khim., 2003, p. 225.
7. Hedges, A.R., Chem. Rev., 1998, vol. 98, p. 2035.
b. Compound VIII was obtained from 0.40 g
(0.352 mmol) of β-cyclodextrine, 0.24 g (2.33 mmol)
of N,N-dimethylaniline in 10 ml of DMF, and 0.16 g
(2.06 mmol) of acetyl chloride in 5 ml of DMF. Yield
0.24 g (55%), mp 167–168°C (decomp.), Rf 0.70 (C).
8. Pitha, J., Szabo and Fales, H.M., Carbohydr. Res., 1987,
vol. 168, p. 191; Rao, C.T., Lindberg, B., Lindberg, J., and
Pitha, J. J. Org. Chem., 1991, vol. 56, p. 1327; Lindberg, B.,
Lindberg, J., Pitha, J., Rao, C.T., and Harata, K., Carbohydr.
Res., 1991, vol. 222, p. 113.
13
1H and C NMR spectra coincide with the spectra de-
9. Senyushkina, I.A., Kurochkina, G.I., Grachev, M.K., Grin-
berg, V.A., Batalova, T.A., and Nifant’ev, E.E., Zh. Obshch.
Khim., 2009, vol. 79, p. 995.
scribed under method a.
ACKNOWLEDGMENTS
10. Fügedi, P. and Nánási, P., Carbohydr. Res., 1988, vol. 175,
p. 173.
The study was carried out under the financial support
of the Russian Foundation for Basic Research (grant
no. 08-03-00374a) and of the Program of the President
of the Russian Federation for the support of the leading
scientific schooles (project no. NSh-8034.2010.5).
11. Takeo, K., Uemura, K., and Mitoh, H., J. Carbohydr. Chem.,
1988, vol. 7, p. 293.
12. Takeo, K., Mitoh, H., and Uemura, K., Carbohydr. Res.,
1989, vol. 187, p. 203.
13. Baer.H., Shen., González.S., Berenguel.V., and García, I.,
Carbohydr. Res., 1992, vol. 235, p. 129; Hanessian, S.,
Benalil,A., and Laferrière, C., J. Org. Chem., 1995, vol. 60,
p. 4786.
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