Reaction of several resveratrol glycoside derivatives with hypochlorites in various media

Article abstract of DOI:10.1007/s10600-012-0146-z

The reactions of pterostilbenoside (trans-3,5-dimethoxystilben-4′-O- β-D-glucoside) and Ar-O-Tr derivatives of resveratroloside (3,5-dihydroxystilben-4′-O-β-D-glucoside) and pinostilbenoside (3-methoxy-5-hydroxystilben-4′-O-β-D-glucoside) with NaOCl and t-BuOCl in the presence of the stable nitroxyl radical TEMPO were studied in various media. It was found that the principal product of pterostilbenoside transformation was its 2,6-dichloroderivative, a part of which was oxidized to form 2,6-dichloropterostilbene glucuronide. Trityl ethers of resveratroloside and pinostilbenoside reacted with the hypochlorites to form mixtures of products.

Full text of DOI:10.1007/s10600-012-0146-z

Chemistry of Natural Compounds, Vol. 48, No. 1, March, 2012 [Russian original No. 1, January-February, 2012]
REACTION OF SEVERAL RESVERATROL GLYCOSIDE
DERIVATIVES WITH HYPOCHLORITES IN VARIOUS MEDIA
1*
1
2
A. D. Rogachev, N. I. Komarova, A. V. Pozdeeva,
UDC 547.9+547.636.3
1
1
1
D. V. Korchagina, V. G. Vasilꢀev, N. F. Salakhutdinov,
and G. A. Tolstikov
1
The reactions of pterostilbenoside (trans-3,5-dimethoxystilben-4ꢀ-O-ꢁ-D-glucoside) and Ar–O–Tr derivatives
of resveratroloside (3,5-dihydroxystilben-4ꢀ-O-ꢁ-D-glucoside) and pinostilbenoside (3-methoxy-5-
hydroxystilben-4ꢀ-O-ꢁ-D-glucoside) with NaOCl and t-BuOCl in the presence of the stable nitroxyl radical
TEMPO were studied in various media. It was found that the principal product of pterostilbenoside
transformation was its 2,6-dichloroderivative, a part of which was oxidized to form 2,6-dichloropterostilbene
glucuronide. Trityl ethers of resveratroloside and pinostilbenoside reacted with the hypochlorites to form
mixtures of products.
Keywords: resveratrol, stilbene glycosides, oxidation, hypochlorites, triphenylmethyl ethers, TEMPO.
Resveratrol (trans-3,5,4ꢀ-trihydroxystilbene, 1) is a natural phytoalexin that occurs in several plants, e.g., grapes,
peanuts, cranberries, etc. [1–3]. It was discovered that 1 exhibits a broad spectrum of biological activities such as antitumor,
antioxidant, anti-inflammatory, cardioprotective, etc. [4]. Its principal metabolites in vivo in humans, mice, and rats are
glucuronide or sulfonated derivatives [5–8].
OR
4'
2
7
RO
5
1'
1
8
3
OR
1 - 5
1
1: R = R = R = H; 2: R = R = H, R = CH
3
1
2
2
1
3: R = R = H, R = Glc; 4: R = H, R = CH , R = Glc
1
2
1
3
2
5: R = R = CH , R = Glc
1
3
2
Glycosides of resveratrol and its derivatives also occur in nature. It was discovered that plants of the family Pinaceae
are rich sources of stilbenes [9]. For example, bark of Siberian pine (Pinus sibirica) contained resveratrol (1), its monomethyl
ether pinostilbene (2), and their 4ꢀ-O-ꢁ-D-glucopyranosides resveratroloside (3) and pinostilbenoside (4) [10–12].
Despite extensive studies of the biological activities of resveratrol and many other stilbenes, the activities of its
glycosylated derivatives are little studied. The reactivities of this class of compounds also have not been studied in detail.
However, the syntheses of glycosylated derivatives of resveratrol, in particular, its mono- and diglucosides and 4ꢀ-glucuronide
have been reported [13–15].
Because one of the metabolic pathways of resveratrol in vivo is the formation of its glucuronide, the availability of
glucuronide derivatives of resveratrol is important for systematic biological investigations.
One method for synthesizing glucuronides is the addition of a protected glucuronide moiety to the aglycon and
subsequent removal of the protecting groups. Another method for synthesizing glucuronides that has been more widely
employed is selective oxidation of the carbohydrate primary alcohol of the corresponding glucoside by sodium hypochlorite
1) N. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch, Russian Academy of Sciences,
Prosp. Akad. Lavrentꢀeva, 9, Novosibirsk, 630090, Russia, fax: (383) 330 97 52, e-mail: rogachev@nioch.nsc.ru,
artrogachev@yandex.ru; 2) Novosibirsk State University, Ul. Pirogova, 2, Novosibirsk, 630090, Russia. Translated from
Khimiya Prirodnykh Soedinenii, No. 1, January–February, 2012, pp. 5–11. Original article submitted June 22, 2011.
©
0009-3130/12/4801-0001 2012 Springer Science+Business Media, Inc.
1

(NaOCl) in the presence of a catalytic amount of a stable nitroxyl radical (TEMPO, etc.). This system was used to synthesize
glucuronides from glucosides of various aglycons including those occurring naturally [16–18].
The goal of the present work was to synthesize several derivatives of resveratroloside and pinostilbenoside that were
isolated from bark of P. sibirica and to study their reactions with NaOCl and t-BuOCl in the presence of TEMPO in various
media.
Because one of the reagents in the studied reactions was the stable radical TEMPO, which forms H-bonds with
phenols or cleaves the H atom from them [19, 20], it became necessary to protect the aromatic hydroxyls of 2 and 3. Thus, we
prepared dimethyl ether 5 (pterostilbenoside) and the Ar–O–Tr ethers of resveratroloside and pinostilbenoside.
The reaction of 3 with CH I in refluxing acetone in the presence of K CO gave after 4 h according to HPLC an
3
2
3
insignificant amount of 4 and only traces of 5. Apparently the low reactivity of 3 in this instance was due to the low solubilities
in acetone of both the starting material and the reaction products. The reaction of 3 or 4 with CH I (4 and 2 eq, respectively)
3
in refluxing CH CN in the presence of K CO formed 5 in 70–80% yield after chromatographic purification. Methylation of
3
2
3
the sugar hydroxyls under these conditions was not observed.
Mixing 3 or 4 with TrCl (2.2 and 1.1 eq, respectively) in CH CN and subsequent addition of NEt to the mixture at
3
3
13
room temperature gave two reaction products. According to PMR and C NMR spectroscopy, not only the aromatic hydroxyls
but also the carbohydrate primary OH group were tritylated under these conditions. As a result, 3 produced bis- and tris-trityl
derivatives 6 and 7; 4, 8 and 9. Full conversion of the starting materials occurred after 24 h at room temperature. The product
ratios from these reactions were ~3:2 for 6 and 7; ~1:1, for 8 and 9.
OR
OGlc
O
1
Cl
3
B
1
7
6
H CO
NH
3
8
8
3
N
A
10
9
1
5
O
O
1'
O
7
R
2
Cl
1''
CH OR
4'
1'
2
2
O
4'
OCH
3
O
13
HO
OH
HO
11, 12
10
6 - 9
OH
11: R = CH OH; 12: R = CO H
2
2
6: R = Tr, R = H; 7: R = Tr
OCH
Cl
1
2
1
3
8: R = CH , R = H; 9: R = CH
Cl
1
3
2
1
3
H CO
3
Ph
Ph
15
14
7, 9: R =
18
2
COOH
OH
O
HO
O
13
OH
The mole ratio of products 6:7 was ~4:1; the yields of 6 and 7 after column chromatography, 75 and 18%, respectively,
after treatment of 3 first with NEt (4–6 eq) and then TrCl (2.1 eq). The reaction was stopped after 4.5–5 h at room temperature.
3
The reaction of 4 with TrCl (1.1 eq) under analogous conditions gave 8 and 9 in yields of 73 and 19%, respectively.
The reaction of 5 with NaOCl (3.3 eq) in the presence of TEMPO in i-PrOH:H O (1:1, v/v) formed only one product
2
according to HPLC. The same product was obtained according to HPLC by treatment of 5 with NaOCl in the presence of
n-Bu NBr (TBAB) and NaBr in EtOAc + sat. aqueous NaHCO (1:1) at 0°C. (Use of NaBr should accelerate oxidation of the
4
3
primary hydroxyl because the hypobromite formed by reaction of NaBr and NaOCl oxidizes TEMPO to the oxonium ion more
rapidly than NaOCl [21].) Also, treatment of 5 with NaOCl in the presence of n-Bu NF in CH Cl + sat. aqueous NaHCO at
4
2
2
3
room temperature proceeded analogously (Table 1).
13
Resonances for the sugar C atoms in the C NMR spectrum of the resulting product agreed fully with those of the
starting material [anomeric C atom with chemical shift (CS) 100.4 ppm; four doublets, 70–80; one triplet, 60.8]. Resonances
in the range 170–180 ppm that would indicate a carboxylic acid had formed were missing in the C NMR spectrum. The set
13
13
of resonances for the aglycon changed in the C NMR spectrum of this product. Doublets with CS 104.3 ppm corresponding
to C-2 and C-6 of the starting material disappeared. The singlet with CS 160.7 corresponding to C-3 and C-5 shifted to
stronger field to CS 154.4. The CS of C-4 (97.3) in the reaction product also differed from that in the starting material (99.7).
Resonances of the C atoms of the double bond, which were situated between the aromatic rings, also shifted relative to those
in the starting material. The resonance with the smaller CS (C-7, 126.8) shifted to stronger field (121.0); with the larger CS
(C-8, 128.6), to weaker field (136.1). The CSs of C atoms in ring B were practically unchanged. This indicated that only the
structure of ring A changed although its symmetry relative to the axis passing through C-1 and C-4 was not destroyed.
2

TABLE 1. Reaction Conditions for Oxidation of Substrates (5, 6, 8, 11), Reagent Ratios, and Formed Products
Oxidative system and reaction conditions
Product
5
3.3 eq NaOCl, 0.2 eq TEMPO, -PrOH + H O (1:1)
4 eq NaOCl, 0.01 eq TEMPO, 0.08 eq TBAB, 0.2 eq NaBr; EtOAc + sat. NaHCO3 (1:1), 0 C
2 eq NaOCl, 0.03 eq TEMPO, 0.15 eq TBAF; CH2Cl2 + sat. NaHCO3 (1:1)
5.5 eq NaOCl, 0.15 eq TEMPO, 0.07 eq TBAB, 0.3 eq NaBr; CH2Cl2 + sat. NaHCO3 (1:1), 0 C
4 eq NaOCl, 0.1 eq TEMPO, 0.07 eq TBAB, 0.2 eq NaBr; CH2Cl2 + sat. NaHCO3 (1:1), 0ꢂC
6 eq NaOCl, 0.15 eq TEMPO, 1.1 eq PhCH2(CH3)3NCl; CH2Cl2 + sat. NaHCO3 (1:1)
i
10
10
10
2
ꢂ
10 + 13 (~1:1.5)
10 + 13 (~1:1)
10 + 13 (~1:4)
ꢂ
(~20:1)
10 + 13
10
2.2 eq -BuOCl, 0.1 eq TEMPO; CH Cl + sat. NaHCO (1:1)
t
2
2
3
5 eq -BuOCl, 0.1 eq TEMPO; sat. NaHCO
t
t
3
(~2:1)
10 + 13
5 eq -BuOCl, 0.05 eq TEMPO, 0.1 eq TBAB, 0.1 eq NaBr; CH Cl + sat. NaHCO (1:1)
2
2
3
6
Sugar resonances in 13C NMR
spectra corresponded to
glucoside; stilbene moiety was
chlorinated.
2 eq NaOCl, 0.1 eq TEMPO, 0.25 eq TBAF; CH2Cl2 + sat. NaHCO3 (1:1)
20 eq NaOCl, 0.1 eq TEMPO, 0.25 eq TBAB, 0.1 eq NaBr; CH2Cl2 + sat. NaHCO3 (1:1), 0ꢂC
8
2.2 eq NaOCl, 0.06 eq TEMPO, 0.3 eq TBAF; CH2Cl2 + sat. NaHCO3 (1:1)
11
5.5 eq NaOCl, 0.1 eq TEMPO, 0.07 eq TBAB; CH2Cl2 + sat. NaHCO3 (1:1), 0ꢂC
5 eq NaOCl, 0.1 eq TEMPO, 0.1 eq PhCH2(CH3)3NCl; CH2Cl2 + sat. NaHCO3 (1:1)
12
Analysis of the reaction product by HPLC/MS (electrospray ionization) detected in positive-ion mode an adduct with
Na of masses (m/z) 509.075 and 511.070; in negative-ion mode, an adduct with Cl with a base peak at 523.051. The results
+
–
agreed unambiguously with empirical formula C H Cl O for the product. The calculated masses (m/z) were for [C H Cl O
22 24
2
8
22 24
2 8
+
–
+ Na ], 509.074 and 511.072; for [C H Cl O + Cl ], 523.052 taking into account the isotopic distribution of Cl. The
22 24
2 8
relative intensities of the calculated isotopic peaks agreed well with those observed experimentally.
By comparing the empirical formulas of the product (C H Cl O ) and the starting material (C H O ) and taking
22 24
2
8
22 26 8
13
into account the PMR and C NMR spectra, it could be confirmed that electrophilic substitution of two H atoms by Cl atoms
had occurred during the course of the reaction. This occurred at the 2- and 6-positions of aromatic ring A (taking into account
13
the C NMR spectra) to form 10.
The fact that oxidation of the glucose primary alcohol that usually occurs under these conditions was not observed in
these reactions was surprising. Therefore, we decided to study the oxidizing capacity of the system using oxidation of a sugar
bonded to thymidine (11) as an example.
Addition of NaOCl (~5.5 eq) to a solution of 11 in CH Cl + sat. NaHCO in the presence of TEMPO, TBAB, and
2
2
3
NaBr at 0°C resulted in practically complete conversion of the substrate to form according to HPLC only one reaction product.
13
Its C NMR spectrum contained a singlet with CS 176.6 ppm and lacked the triplet at 62 ppm that corresponded to the
CH OH group of the deoxyribose moiety. Resonances of the other sugar C atoms were shifted relative to those of the starting
2
material. However, their multiplicity remained the same. The CSs of resonances corresponding to the thymine aglycon were
practically unchanged. Their multiplicity remained the same. All this indicated that the primary hydroxyl of deoxyribose was
13
oxidized during the course of the reaction to form carboxylic acid 12. The C NMR spectra of the oxidation product were
similar to those published [22–24], for which the synthesis was carried out using oxidation of thymidine by oxygen in the
presence of PtO .
2
Product 12 was also prepared by treatment of 11 with NaOCl in CH Cl + sat. NaHCO in the presence of
2
2
3
PhCH (CH ) NCl and a catalytic amount of TEMPO. The reaction was carried out without NaBr at room temperature.
2
3 3
Two products with very similar retention times in reversed-phase HPLC were formed by treatment of 5 with NaOCl
(5.5 eq) in the presence of TEMPO, NaBr, and TBAB in CH Cl + sat. NaHCO at 0°C. The CSs and multiplicity of resonances
2
2
3
13
in the C NMR spectrum of the reaction mixture indicated that an aromatic ring of the starting material was chlorinated
during the reaction. However, a double set of resonances was observed in the range 70–80 ppm that corresponded to the
glycoside moiety. In addition to doublets for C-2ꢀꢀ–C-5ꢀꢀ of the glucose, doublets with CSs 71.42, 73.01, 75.49, and 75.83 with
approximately the same intensities and about 1.5 times as strong as the glucoside resonances were also observed. The spectrum
also showed a doublet at 99.78 that was characteristic of an anomeric C atom and a singlet at 170.19.
3

The PMR spectrum exhibited in the range 4.9–5.2 ppm a doublet at 4.89 (J = 7.3 Hz) that corresponded to a glucose
anomeric proton and a doublet at 5.09 (J = 7.3 Hz), the intensity of which was about 1.7 times greater than the first. By
comparing the results, we concluded that oxidation of a certain amount of the produced dichloro-derivative 10 had apparently
occurred during the course of the reaction to form glucuronide 13. Their ratio in the mixture was about 1:1.5–1.7. An attempt
to separate 10 and 13 by column chromatography over silica gel was unsuccessful because 13 was apparently irreversibly
absorbed on the SiO .
2
The amount of the formed glucuronide would be smaller if a smaller amount of oxidant and NaBr were used. However,
addition of a larger amount of NaOCl would not increase significantly the amount of 13.
The largest amount of 13 in the mixture with 10 was observed in an experiment using the phase-transfer
13
catalyst PhCH (CH ) NCl and NaOCl (~6 eq). Doublets in the C NMR spectrum in the range 70–80 ppm corresponded to
2
3 3
C-2ꢀꢀ–C-5ꢀꢀ of the glucuronide carbohydrate and were about four times stronger than the resonances of the glucoside. Using
a larger amount of oxidant did not increase the amount of 13.
Chlorination of aromatic substrates during their reaction with NaOCl was reported earlier [25, 26]. Alkylhypochlorites,
in particular t-BuOCl, were used as the oxidants in several instances in order to avoid such processes. We also studied the
reaction of the synthesized resveratroloside derivatives with t-BuOCl.
Treatment of 5 (2.2–3 eq) with t-BuOCl in CH Cl + sat. NaHCO in the presence of TEMPO without quaternary
2
2
3
13
13
ammonium salts gave dichloride 10. (The C NMR spectrum contained resonances with CS 112 ppm.) The C NMR
spectrum also showed weak resonances with CSs 71.4, 73.0, 75.5, and 75.8 that were consistent with the presence of 13 in the
mixture. Only dichloro-derivative 10 was formed if this reaction was carried out without an organic solvent in sat. NaHCO
3
solution.
Treatment of 5 with an excess of t-BuOCl in CH Cl + sat. NaHCO in the presence of TEMPO and NaBr formed a
2
2
3
mixture of 10 and 13 in a ~2:1 ratio.
Treatment of tritylated derivatives 6 and 8 with NaOCl and with t-BuOCl in CH Cl + sat. NaHCO in the presence
2
2
3
of various quaternary ammonium salts also did not lead to complete oxidation of the primary alcohol of the substrate sugar
moiety, regardless of whether a quaternary ammonium salt or NaBr was used in the reaction. IR spectra of the reaction
–1
products either did not contain in the range 1750–1690 cm an absorption band characteristic of a carboxylic acid or the band
13
was very weak. The C NMR spectrum exhibited singlets with CS ~112 ppm that indicated the stilbene aromatic ring was
chlorinated. In any case, selective and complete oxidation of the sugar could not be achieved in these reactions.
Thus, several derivatives of resveratroloside and pinostilbenoside were synthesized. Their reactions with NaOCl and
t-BuOCl in the presence of the stable nitroxyl radical TEMPO in various solvents were studied. The principal product from
reaction of dimethyl resveratroloside derivative 5 with NaOCl and t-BuOCl was 2,6-dichloro-3,5-dimethoxystilben-4ꢀ-O-ꢁ-
D-glucopyranoside (10). The glucoside moiety was partially oxidized to the glucuronide. However, the amount of formed
glucuronide depended on the amount of oxidant. Reactions of Ar–O–Tr derivatives of resveratroloside and pinostilbenoside
with NaOCl and t-BuOCl formed mixtures of chlorination products of the stilbene substrates.
EXPERIMENTAL
HPLC chromatographic analysis was carried out on a Milikhrom A-02 instrument (ZAO Institute of Chromatography
EkoNova, Novosibirsk) using a column (2 ꢃ 75 mm) packed with reversed-phase sorbent Prontosil-120-5-C18 AQ (5 ꢄm)
thermostatted at 35°C. Gradient elution by trifluoroacetic acid solution (0.1%) and MeOH (100%) at flow rate 150 ꢄL/min
was used.
HPLC/MS analysis was performed in an Agilent chromatograph with a micrOTOF-Q hybrid quadrupole time-of-
flight mass spectrometer (Bruker) using electrospray ionization at atmospheric pressure (API-ES) in positive-ion and negative-
ion modes in the range m/z 100–1500. The drying gas was N at 4 L/min, 220°C, and 1.0 bar. A solution of the compound in
2
MeOH (~1 mg/mL) was fed into the spray chamber at flow rate 180 ꢄL/h using a syringe pump.
t-Butylhypochlorite was synthesized by the literature method [27]. Household bleach with NaOCl mass concentration
5.0–5.2% was used. Solvents were distilled before use. Glycosides 2 and 3 were isolated from bark of P. sibirica using a
procedure developed by us that was based on a patent [12]. Melting points were measured on a FP900 instrument (Mettler
Toledo).
4

13
PMR and
C NMR spectra were recorded in CDCl and DMSO-d on Bruker AV-300 (operating frequencies
3 6
1
13
1
13
1
300.13 MHz for H and 75.47 MHz for C), AM-400 (400.13 MHz, H; 100.61 MHz, C), and DRX-500 (500.13 MHz, H;
125.76 MHz, C) spectrometers (Bruker). The internal standards were resonances of CD(H)Cl (ꢅ 7.24 ppm, ꢅ 76.90 ppm)
13
3
H
C
and DMSO (ꢅ 2.49 ppm, ꢅ 39.50 ppm). The structures of the compounds were established using NMR methods based on
H
C
1
1
13
analysis of PMR spectra, in several instances H– H double resonance spectra, and C NMR spectra recorded in JMOD
mode. Two-dimensional heteronuclear C– H correlation spectra for direct (C–H COSY, J
13
1
1
= 160 Hz) and through-space
C,H
1
(COLOC, J
= 10 Hz) spin–spin coupling constants were recorded.
C,H
Extraction and Isolation. Ground bark of P. sibirica (492.4 g) was extracted with EtOH (95%) in a Soxhlet apparatus
for 40 h. The EtOH extract was filtered. The solvent was vacuum distilled to afford an extract (127.4 g) that was worked up
with methyl-t-butylether (MTBE, 1200 mL) by stirring at room temperature for 5 h and filtering. The filtrate was discarded.
The MTBE extraction was repeated twice (280 mL each) to afford an ether-insoluble solid (61.3 g) that was separated by
chromatography over SiO (5 g substance per 220 g SiO , CHCl :EtOH eluent, 9:1ꢆ0:10) to afford resveratroloside (3, 1.2 g)
2
2
3
and pinostilbenoside (4, 1.7 g). The spectral characteristics of the isolated compounds agreed with those reported [12, 28].
Methylation of 3 and 4. Resveratroloside (3, 2.00 g, 5.1 mmol) in CH CN (100 mL) was treated with K CO
3
3
2
(4.22 g, 30.5 mmol) and CH I (1.90 mL, 4.35 g, 30.6 mmol). The mixture was refluxed with a CaCl trap for 24 h and filtered.
3
2
The solvent was vacuum distilled. The product was chromatographed over a column of SiO (600 mg substance per 30 g
2
SiO , CHCl :EtOH eluent, 10:0.1ꢆ0:0.5) to afford 5 (1.50 g, 3.6 mmol, 70% yield).
2
3
The reaction of pinostilbenoside (4, 1.50 g, 3.7 mmol) with CH I (1.38 mL, 3.16 g, 22.2 mmol) and K CO (3.0 g,
3
2
3
21.7 mmol) under analogous conditions formed 5 (1.24 g, 3.0 mmol, 80% yield).
trans-3,5-Dimethoxystilben-4ꢀ-O-ꢁ-D-glucopyranoside (5), mp 90.7°C.
PMR spectrum (DMSO-d , ꢅ, ppm, J/Hz): 3.10–3.52 (5H, m, H-2ꢀꢀ, H-3ꢀꢀ, H-4ꢀꢀ, H-5ꢀꢀ, H-6ꢀꢀa); 3.65–3.73 (1H, m,
6
H-6ꢀꢀb); 3.76 (6H, s, 2 ꢃ OCH ); 4.62 (1H, dd, J
= 5.9; J
= 5.1, CH OH-6ꢀꢀ); 4.88 (1H, d, J
= 7.3, H-1ꢀꢀ); 5.04
3
OH,6ꢇa
OH,6ꢇb
2
1ꢇ,2ꢇ
(1H, d, J = 5.1, CHOH-4ꢀꢀ); 5.10 (1H, d, J = 4.1, CHOH-3ꢀꢀ); 5.34 (1H, d, J = 4.5, CHOH-2ꢀꢀ); 6.38 (1H, br.t, J = 2.0, H-4); 6.73
(2H, d, J = 2.0, H-2, H-6); 7.02 (2H, d, J = 8.7, H-3ꢀ, H-5ꢀ); 7.04 (1H, d, J = 16.4, H-7); 7.20 (1H, d, J = 16.4, H-8); 7.52
7,8
8,7
(2H, d, J = 8.7, H-2ꢀ, H-6ꢀ).
13
C NMR spectrum (DMSO-d , ꢅ, ppm): 55.27 (q, 2 ꢃ OCH ); 60.79 (t, C-6ꢀꢀ); 69.81 (d, C-4ꢀꢀ); 73.33 (d, C-2ꢀꢀ);
6
3
76.68 (d, C-3ꢀꢀ); 77.12 (d, C-5ꢀꢀ); 99.66 (d, C-4); 100.35 (d, C-1ꢀꢀ); 104.33 (d, C-2, C-6); 116.53 (d, C-3ꢀ, C-5ꢀ); 126.77 (d,
C-7); 127.77 (d, C-2ꢀ, C-6ꢀ); 128.55 (d, C-8); 130.80 (s, C-1ꢀ); 139.44 (s, C-1); 157.22 (s, C-4ꢀ); 160.74 (s, C-3, C-5).
+
–
ESI-MS: found for [C H O + Na ], 441.150; calc. 441.152; found for [C H O + Cl ], 453.129; calc. 453.132.
22 26
8
22 26 8
Tritylation of Resveratroloside (3). Compound 3 (2 g, 5 mmol) in CH CN (150 mL) was treated with NEt
3
3
(1.4 mL, 1.0 g, 10 mmol), stirred for 20–30 min, treated with TrCl in portions of 0.3–0.4 g (2.78 g, 10 mmol), and stirred for
4.5 h at room temperature. The solvent was vacuum distilled. The solid was chromatographed over SiO (1 g of substance per
2
20 g SiO , CHCl :EtOH eluent, 10:0ꢆ8:2) to afford 6 (3.37 g, 3.85 mmol, 75% yield) and 7 (1.04 g, 0.93 mmol, 18% yield).
2
3
trans-3,5-Bis(triphenylmethyloxy)stilben-4ꢀ-O-ꢁ-D-glucopyranoside (6), mp 97.4°C.
PMR spectrum (DMSO-d , ꢈꢅ, ppm, J/Hz): 3.19 (1H, ddd, J = 9.5, 8.5, 5.0, H-4ꢀꢀ); 3.26 (1H, ddd, J
= 9.0,
2ꢇ,3ꢇ
6
J
= 7.4, J = 4.8, H-2ꢀꢀ); 3.30 (1H, ddd, J = 9.0, 8.5, 4.2, H-3ꢀꢀ); 3.32–3.37 (1H, m, H-5ꢀꢀ); 3.49 (1H, ddd, J = 11.7, 5.6, 5.6,
2ꢇ,1ꢇ
H-6ꢀꢀa); 3.72 (1H, ddd, J = 11.7, 5.1, 2.0, H-6ꢀꢀb); 4.52 (1H, dd, J = 5.6, 5.1, CH OH-6ꢀꢀ); 4.86 (1H, d, J = 7.4, H-1ꢀꢀ); 4.96 (1H,
2
d, J = 5.0, CHOH-4ꢀꢀ); 5.01 (1H, d, J = 4.2, CHOH-3ꢀꢀ); 5.25 (1H, d, J = 4.8, CHOH-2ꢀꢀ); 6.08 (1H, t, J = 2.1, H-4); 6.33 (2H,
d, J = 2.1, H-2, H-6); 6.62 (1H, d, J = 16.3, H-7), 6.65 (1H, d, J = 16.3, H-8); 6.98 (2H, d, J = 8.8, H-3ꢀ, H-5ꢀ); 7.12–7.18
7,8
8,7
(12H, m, H-11); 7.19–7.27 (18H, m, H-12, H-13); 7.36 (2H, d, J = 8.8, H-2ꢀ, H-6ꢀ).
2
13
C NMR spectrum (DMSO-d , ꢅ, ppm): 60.74 (t, C-6ꢀꢀ); 69.77 (d, C-4ꢀꢀ); 73.21 (d, C-2ꢀꢀ); 76.60 (d, C-3ꢀꢀ); 77.00 (d,
6
C-5ꢀꢀ); 89.89 (s, 2 ꢃ C-9); 100.37 (d, C-1ꢀꢀ); 113.52 (d, C-4); 113.61 (d, C-2, C-6); 116.43 (d, C-3ꢀ, C-5ꢀ); 125.91 (d, C-7);
126.98 (d, 6 ꢃ C-13); 127.47 (d, C-2ꢀ, C-6ꢀ); 127.59 (d, 12 ꢃ C-12); 127.99 (d, C-8); 128.19 (d, 12 ꢃ C-11); 130.48 (s, C-1ꢀ);
137.47 (s, C-1); 143.51 (s, 6 ꢃ C-10); 155.60 (s, C-3, C-5); 157.06 (s, C-4ꢀ).
+
–
ESI-MS: found for [C H O + Na ], 897.334; calcd 897.340; found for [C H O + Cl ], 909.323; calcd 909.320.
58 50
8
58 50 8
trans-3,5,6ꢀꢀ-Tris(triphenylmethyloxy)stilben-4ꢀ-O-ꢁ-D-glucopyranoside (7), mp 133.4°C.
PMR spectrum (CDCl , ꢅ, ppm J/Hz): 3.27–3.70 (6H, m, H-2ꢀꢀ, H-3ꢀꢀ, H-4ꢀꢀ, H-5ꢀꢀ, CH -6ꢀꢀ); 4.11, 4.47, 4.95 (1H
3
2
each, all br.s, 3 ꢃ OH); 4.87 (1H, d, J
= 7.5, H-1ꢀꢀ); 6.28 (2H, s, H-2, H-6); 6.48 (1H, s, H-4); 7.08 (2H, d, J
= J
= 8.8,
1ꢇ,2ꢇ
3ꢀ,2ꢀ
5ꢀ,6ꢀ
H-3ꢀ, H-5ꢀ); 7.14–7.50 (m, H-8 and other protons).
13
C NMR spectrum (CDCl , ꢅ, ppm): 63.53 (t, C-6ꢀꢀ); 70.73 (d, C-4ꢀꢀ); 73.21 (d, C-2ꢀꢀ); 75.04 (d, C-3ꢀꢀ); 76.54 (d,
3
C-5ꢀꢀ); 86.68 (s, C-14); 90.63 (s, 2 ꢃ C-9); 100.46 (d, C-1ꢀꢀ); 114.41 (d, C-2, C-6); 114.80 (d, C-4); 117.01 (d, C-3ꢀ, C-5ꢀ);
5

126.88 (d, 6 ꢃ C-13); 126.96 (d, 3 ꢃ C-18); 127.41 (d, C-7); 127.50 (d, 12 ꢃ C-12); 127.63 (d, C-2ꢀ, C-6ꢀ); 127.75 (d, 6 ꢃ C-17);
128.53 (d, C-8); 128.61 (d, 6 ꢃ C-16); 128.77 (d, 12 ꢃ C-11); 131.80 (s, C-1ꢀ); 137.36 (s, C-1); 143.69 (s, 3 ꢃ C-15); 143.91
(s, 6 ꢃ C-10); 156.11 (s, C-3, C-5); 156.49 (s, C-4ꢀ).
–
ESI-MS: found for [C H O + Cl ], 1151.438; calcd 1151.430.
77 64
8
Tritylation of Pinostilbenoside (4). Compound 4 (2 g, 4.95 mmol) in CH CN (250 mL) was treated with NEt
3
3
(1 mL, 0.7 g, 7 mmol), stirred for 20–30 min, treated with tritylchloride (1.4 g, 4.9 mmol), and stirred for 4.5 h at room
temperature. The solvent was vacuum distilled. The product was purified by flash chromatography over SiO (1 g of substance
2
per 20 g SiO ; eluent CHCl :EtOH, 10:0ꢆ5:5) to afford 8 (2.3 g, 3.61 mmol, 73% yield) and 9 (0.8 g, 0.94 mmol, 19% yield).
2
3
trans-3-Methoxy-5-triphenylmethyloxystilben-4ꢀ-O-ꢁ-D-glucopyranoside (8), mp 112.9°C.
PMR spectrum (DMSO-d , ꢅ, ppm, J/Hz): 3.08–3.58 (5H, m, H-2ꢀꢀ, H-3ꢀꢀ, H-4ꢀꢀ, H-5ꢀꢀ, H-6ꢀꢀa); 3.70 (1H, br.dd,
6
J = 11.7, 5.2, H-6ꢀꢀb); 3.49 (3H, s, OCH ); 4.61 (1H, dd, J = 5.6, 5.2, CH OH-6ꢀꢀ); 4.86 (1H, d, J = 7.3, H-1ꢀꢀ); 5.05 (1H,
3
2
1ꢇ,2ꢇ
d, J = 4.9, CHOH-4ꢀꢀ); 5.12 (1H, d, J = 4.0, CHOH-3ꢀꢀ); 5.34 (1H, d, J = 4.8, CHOH-2ꢀꢀ); 6.02 (1H, br.dd, J = 2.0, H-4); 6.53
and 6.57 (2H, both br.s, H-2, H-6); 6.84 (1H, d, J = 16.4, H-7); 6.89 (1H, d, J = 16.4, H-8); 7.00 (2H, d, J = 8.6, H-3ꢀ,
7,8
8,7
H-5ꢀ); 7.16–7.53 (17H, m, other protons).
13
C NMR spectrum (DMSO-d , ꢅ, ppm): 55.01 (q, OCH ); 60.77 (t, C-6ꢀꢀ); 69.79 (d, C-4ꢀꢀ); 73.31 (d, C-2ꢀꢀ); 76.66
6
3
(d, C-3ꢀꢀ); 77.12 (d, C-5ꢀꢀ); 89.55 (c, C-9); 100.33 (d, C-1ꢀꢀ); 104.64 (d, C-2); 105.62 (d, C-4); 110.66 (d, C-6); 116.50 (d,
C-3ꢀ, C-5ꢀ); 126.50 (d, C-7); 127.40 (d, 3 ꢃ C-13); 127.73 (d, C-2ꢀ, C-6ꢀ); 128.03 (d, 6 ꢃ C-12); 128.42 (d, C-8, 6 ꢃ C-11);
130.62 (s, C-1ꢀ); 138.52 (s, C-1); 143.74 (s, 3 ꢃ C-10); 156.92, 157.20 (both s, C-4ꢀ, C-5); 159.46 (s, C-3).
+
–
ESI-MS: found for [C H O + Na ], 669.245; calcd 669.246; found for [C H O + Cl ], 681.227; calcd 681.226.
40 38
8
40 38 8
trans-3-Methoxy-5,6ꢀꢀ-bis(triphenylmethyloxy)stilben-4ꢀ-O-ꢁ-D-glucopyranoside (9), mp 113°C (dec).
PMR spectrum (CDCl , ꢅ, ppm, J/Hz): 3.21–3.73 (6H, m, H-2ꢀꢀ, H-3ꢀꢀ, H-4ꢀꢀ, H-5ꢀꢀ, CH -6ꢀꢀ); 3.54 (3H, s, OCH );
3
2
3
4.00, 4.43, 5.16 (1H each, all br.s, 3 ꢃ OH); 4.85 (1H, d, J
= 7.3, H-1ꢀꢀ); 6.19 (1H, br.dd, J = 2.0, H-4); 6.50 and 6.53 (1H
1ꢇ,2ꢇ
each, both br.s, H-2, H-6); 6.66 (1H, d, J = 16.4, H-7); 6.72 (1H, d, J = 16.4, H-8); 7.07 (2H, d, J = 8.5, H-3ꢀ, H-5ꢀ);
7,8
8,7
7.11–7.56 (m, H-2ꢀ, H-6ꢀ, other protons).
13
C NMR spectrum (CDCl , ꢅ, ppm): 55.07 (q, OCH ); 63.53 (t, C-6ꢀꢀ); 70.80 (d, C-4ꢀꢀ); 73.18 (d, C-2ꢀꢀ); 74.93 (d,
3
3
C-3ꢀꢀ); 76.40 (d, C-5ꢀꢀ); 86.72 (s, C-14); 90.51 (s, C-9); 100.27 (d, C-1ꢀꢀ); 105.35 (d, C-2); 106.20 (d, C-4); 111.68 (d, C-6);
117.14 (d, C-3ꢀ, C-5ꢀ); 127.02, 127.17, 127.60, 127.68, 127.81, 127.87, 128.10 (all d, C-2ꢀ, C-5ꢀ, C-7, C-8, 6 ꢃ C-12, 3 ꢃ C-13,
6 ꢃ C-17, 3 ꢃ C-18); 128.62 and 128.87 (both d, 6 ꢃ C-11, 6 ꢃ C-16); 131.81 (s, C-1ꢀ); 138.27 (s, C-1); 143.69 and 144.01 (both
s, 3 ꢃ C-10, 3 ꢃ C-15); 156.46 (s, C-4ꢀ); 157.50 (s, C-5); 159.65 (s, C-3).
+
–
ESI-MS: found for [C H O + Na ], 911.352; calcd 911.355; found for [C H O + Cl ], 932.341; calcd 923.336.
59 52
8
59 52 8
General Method for Oxidation. A solution of substrate (0.01–0.05 M), TEMPO, quaternary ammonium salt, and
NaBr (if it was used) in an organic solvent was treated with an equivalent volume of saturated NaHCO solution, stirred and
3
cooled if necessary to 0°C, stirred vigorously and treated dropwise with a mixture of NaOCl solution and an equivalent
volume of saturated NaHCO solution that was cooled beforehand if necessary. If t-BuOCl was used as the oxidant, it was
3
added to the substrate to be oxidized as a solution (5–10%) in an organic solvent. After the whole amount of oxidant was
added, the mixture was stirred at the given temperature for 1.5–2 h and then analyzed by HPLC.
After the starting material was completely converted, the mixture was treated with EtOH or MeOH (0.5–1 mL) or
several milliliters of Na SO solution (10%) to remove the excess of oxidant. The aqueous layer was separated and washed
2
3
with used organic solvent. The organic extracts were combined, washed with H O, and dried over MgSO . The solvent was
2
4
vacuum distilled.
trans-2,6-Dichloro-3,5-dimethoxystilben-4ꢀ-O-ꢁ-D-glucopyranoside (10), mp 92°C (dec).
PMR spectrum (DMSO-d , ꢅ, ppm, J/Hz): 3.20 (1H, dd, J = 9.5, 8.3, H-4ꢀꢀ); 3.27 (1H, dd, J = 9.0, 7.4, H-2ꢀꢀ); 3.31
6
(1H, dd, J = 9.0, 8.3, H-3ꢀꢀ); 3.35 (1H, ddd, J = 9.5, 5.7, 2.1, H-5ꢀꢀ); 3.50 (1H, dd, J = 11.8, 5.7, H-6ꢀꢀa); 3.71 (1H, dd, J = 11.8,
2.1, H-6ꢀꢀb); 3.92 (6H, s, 2 ꢃ OCH ); 4.90 (1H, d, J
= 7.4, H-1ꢀꢀ); 6.86 (1H, s, H-4); 6.95 (1H, d, J = 16.6, H-7), 6.97 (1H,
3
1ꢇ,2ꢇ
7,8
d, J = 16.6, H-8); 7.06 (2H, d, J = 8.8, H-3ꢀ, H-5ꢀ); 7.53 (2H, d, J = 8.8, H-2ꢀ, H-6ꢀ).
8,7
13
C NMR spectrum (DMSO-d , ꢅ, ppm): 56.65 (q, 2 ꢃ OCH ); 60.78 (t, C-6ꢀꢀ); 69.82 (d, C-4ꢀꢀ); 73.26 (d, C-2ꢀꢀ);
6
3
76.63 (d, C-3ꢀꢀ); 77.05 (d, C-5ꢀꢀ); 97.29 (d, C-4); 100.37 (d, C-1ꢀꢀ); 112.72 (s, C-2, C-6); 116.63 (d, C-3ꢀ, C-5ꢀ); 120.96 (d,
C-7); 127.83 (d, C-2ꢀ, C-6ꢀ); 130.03 (s, C-1ꢀ); 135.57 (s, C-1); 136.13 (d, C-8); 154.39 (s, C-3, C-5); 157.65 (s, C-4ꢀ).
+
–
ESI-MS: found for [C H Cl O + Na ], 509.075; calcd 509.074; found for [C H Cl O + Cl ], 523.051;
22 24
2
8
22 24
2 8
calcd 523.052.
6

trans-2,6-Dichloro-3,5-dimethoxystilben-4ꢀ-O-ꢁ-D-glucuronide (13) was characterized as a mixture with 10 (10:13
ratio, ~1:4).
PMR spectrum (DMSO-d , ꢅ, ppm, J/Hz) (resonances of the following protons could be identified): 3.92 (6H, s,
6
2 ꢃ OCH ); 5.09 (1H, d, J
= 7.3, H-1ꢀ); 6.85 (1H, s, H-4); 7.04 (2H, d, J = 8.8, H-3ꢀ, H-5ꢀ); 7.55 (2H, d, J = 8.8, H-2ꢀ, H-6ꢀ).
3
1ꢇ,2ꢇ
Resonances of other protons overlapped resonances of 10 and appeared in the ranges 3.10–3.85 ppm (H-2ꢀꢀ, H-3ꢀꢀ, H-4ꢀꢀ, H-5ꢀꢀ)
and 6.78–7.00 ppm (H-7, H-8).
13
C NMR spectrum (DMSO-d , ꢅ, ppm): 56.73 (q, 2 ꢃ OCH ); 71.43, 73.01, 75.49, 75.83 (d, C-2ꢀꢀ, C-3ꢀꢀ, C-4ꢀꢀ,
6
3
C-5ꢀꢀ); 97.09 (d, C-4); 99.78 (d, C-1ꢀꢀ); 112.58 (s, C-2, C-6); 116.52 (d, C-3ꢀ, C-5ꢀ); 121.17 (d, C-7); 128.03 (d, C-2ꢀ, C-6ꢀ);
130.22 (s, C-1ꢀ); 135.66 (s, C-1); 135.92 (d, C-8); 154.45 (s, C-3, C-5); 157.17 (s, C-4ꢀ); 170.51 (s, C-6ꢀꢀ).
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7