ISSN 1070-3632, Russian Journal of General Chemistry, 2009, Vol. 79, No. 12, pp. 2695–2697. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © R.R. Sharipova, I.Yu. Strobykina, V.E. Kataev, O.A. Lodochnikova, A.T. Gubaidullin, 2009, published in Zhurnal Obshchei Khimii,
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009, Vol. 79, No. 12, pp. 2058–2060.
LETTERS
TO THE EDITOR
Reduction of Steviolbioside
R. R. Sharipova, I. Yu. Strobykina, V. E. Kataev, O. A. Lodochnikova, and A. T. Gubaidullin
Arbuzov Institute of Organic and Physical Chemistry, Kazan Research Center,
Russian Academy of Sciences, ul. Arbuzova 8, Kazan, 420088 Tatarstan, Russia
e-mail: kataev@iopc.knc.ru
Received January 12, 2009
DOI: 10.1134/S1070363209120238
Alkaline hydrolysis of stevioside (I), the major
Thus we were the first to reduce glycoside
(rebaudioside) of the ent-kaurene series, namely ste-
violbioside (II), and obtain alcohol III.
component of sweet glycosides (rebaudiosides) isolated
from Stevia rebaudiana Bertoni [1], yields steviol-
bioside (II) [2]. Unlike stevioside (I), steviolbioside
1
9-Hydroxy-ent-kaur-16-en-13-yl β-D-sophoroside
III). A solution of 1 g of steviolbioside (II) in 30 ml
of anhydrous tetrahydrofuran was added dropwise to a
(
II) is a weaker sweetener [3], but it also exhibits
(
biological activity (hypoglycemic effect [4]), so that it
can be used as a basis for the design of new
biologically active compounds. In fact, esters [5] and
amides [6] derived from steviolbioside were found to
possess antitumor and antibacterial activity.
suspension of 1.5 g of LiAlH in 40 ml of anhydrous
4
THF. The mixture was heated for 12 h under reflux
with stirring, excess LiAlH was decomposed by treat-
4
ment with water, the precipitate was filtered off and
ground with 5% hydrochloric acid, and the product
was extracted into butanol. The extracts were com-
bined and evaporated, and the residue (0.90 g) was
recrystallized from methanol. Yield 0.71 g (73%), mp
In continuation of our studies on the reactivity of
steviolbioside in the present work we examined its
behavior under the reduction conditions. Treatment of
steviolbioside (II) with excess LiAlH in boiling
4
tetrahydrofuran gave 73% of a product which was
20
1
46°C (from MeOH), [α]D = –24° (c = 0.1, H O). IR
assigned the structure of alcohol III on the basis of its
2
–
1
1
spectrum (mineral oil), ν, cm : 3373 (OH), 1660
(C=C). H NMR spectrum (pyridine-d ), δ, ppm (J,
Hz): 1.04 s (3H, C H ), 1.14 s (3H, C H ), 1.5–2.3 m
IR and H NMR spectra (Scheme 1).
1
1
5
The H NMR spectrum of III resembles that of
2
0
18
3
3
initial steviolbioside (II) [6], except for the presence of
doublets at δ 3.53 and 3.93 ppm, which were assigned
(
14H, aglycone), 3.53 d (1H, 19-H , J = 10.79), 3.93 d
A
1
9
(1H, 19-H , J = 10.79), 3.8–4.5 m (12H, sophorose),
B
to methylene protons on C . These findings indicated
that the carboxy group in II was reduced to
hydroxymethyl. The same also followed from the
absence in the IR spectrum of the product of carbonyl
5
.07 s (1H, 17-H ), 5.17 d (1H, 22-H, J = 7.6,), 5.28 d
A
(
1H, 36-H, J = 7.6), 5.74 s (1H, 17-H ). Found, %: C
B
6
1.75; H 8.47. C H O . Calculated, %: C 61.11; H
32 52 12
–
1
8.35.
absorption band at 1690 cm typical of carboxy group.
On the other hand, the IR spectrum of III contained an
Steviolbioside was synthesized according to the
–
1
absorption band at 1665 cm typical of stretching
vibrations of double C=C bond. This means that the
procedure described in [2], mp 190°C (from MeOH),
20
[
α]D = –32.5° (c = 0.2, MeOH); published data [2]:
16
17
C =C double bond was not reduced in the above
20
mp 188–192°C, [α]D = –37.4° (c = 1,4-dioxane).
1
reaction. In the H NMR spectrum of III we observed
1
singlets at δ 5.07 and 5.74 ppm, which clearly belong
The H NMR spectrum was recorded on a Bruker
1
7
to protons in the exocyclic methylene group (C H =)
Avance-600 spectrometer (600 MHz) from a solution
2
[
6]. The structure of the isolated product was
unambiguously proved by the X-ray diffraction data
see figure).
in pyridine-d . The IR spectrum was obtained in
5
mineral oil on a UR-20 spectrometer (spectral range
–
1
(
400–3600 cm ). The optical rotation was determined
2695