Synthesis of per-acetyl D-fucopyranosyl bromide and its use in preparation of diphyllin D-fucopyranosyl glycoside

Article abstract of DOI:10.1080/07328300802030860

The per-O-acetyl-d-fucosyl bromide (9) was expediently prepared for C-6 deoxygenation of d-galactose in six steps in 32.5% yield. Employing phase transfer catalysis glycosylation (PTC), d-fucopyranosyl diphyllin (4), the analog of natural diphyllin glycoside, was synthesized by using 9 as the glycosyl donor in 67.1% in two steps. The product was identified by 1H NMR, 13C NMR, and HRMS. Its abilities to inhibit the growth of cancer cells in vitro also are discussed. Copyright Taylor & Francis Group, LLC.

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Synthesis of Per‐acetyl d‐fucopyranosyl
Bromide and Its Use in Preparation of
Diphyllin d‐fucopyranosyl Glycoside
Zhao Yu a , Lu Ya‐Peng a & Zhu Li a
a Institute of Nautical Medicine , Nantong University , Nantong, Jiangsu,
China
Published online: 28 May 2008.
To cite this article: Zhao Yu , Lu Ya‐Peng & Zhu Li (2008) Synthesis of Per‐acetyl d‐fucopyranosyl Bromide
and Its Use in Preparation of Diphyllin d‐fucopyranosyl Glycoside, Journal of Carbohydrate Chemistry, 27:2,
113-119, DOI: 10.1080/07328300802030860
To link to this article: http://dx.doi.org/10.1080/07328300802030860
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Journal of Carbohydrate Chemistry, 27:113–119, 2008
Copyright # Taylor & Francis Group, LLC
ISSN: 0732-8303 print 1532-2327 online
DOI: 10.1080/07328300802030860
Synthesis of Per-acetyl
D-fucopyranosyl Bromide
and Its Use in Preparation
of Diphyllin D-fucopyranosyl
Glycoside
Zhao Yu, Lu Ya-Peng, and Zhu Li
Institute of Nautical Medicine, Nantong University, Nantong, Jiangsu, China
The per-O-acetyl-D-fucosyl bromide (9) was expediently prepared for C-6 deoxygenation
of D-galactose in six steps in 32.5% yield. Employing phase transfer catalysis glycosyla-
tion (PTC), D-fucopyranosyl diphyllin (4), the analog of natural diphyllin glycoside, was
synthesized by using 9 as the glycosyl donor in 67.1% in two steps. The product was
identified by 1H NMR, 13C NMR, and HRMS. Its abilities to inhibit the growth of
cancer cells in vitro also are discussed.
Keywords D-galactoses, D-fucose, Synthesis, Glycosylation, Antitumor
INTRODUCTION
Diphyllin, an arylnaphthalene lignan isolated from many traditional medicinal
plants, has been reported to possess a wide range of pharmacological activity,
including antitumor and antiviral activities.[1–3] Interestingly, some natural
diphyllin glycosides (1–3, Patentiflorin A, Patentiflorin B, and 400-O-acetyl
patentiflorin B) showed more potent bioactivities than aglycone diphyllin
itself.[4–9] It has been proved that sugar moieties are crucial to their bioactiv-
ities and pharmacokinetics.[4] In order to ascertain the relationship between
the stereochemical orientation of the C-4” hydroxyl group and biological
activity, we set out to synthesize the b-D-fucosyl analog 4 of natural diphyllin
glycosides (Figure 1).
Received October 22, 2007; accepted January 1, 2008.
Address correspondence to Zhao Yu, Institute of Nautical Medicine, Nantong Univer-
sity, 19 Qixiu Road, Nantong, Jiangsu 226001, China. E-mail: zhaoyoo@163.com
113

Z. Yu et al.
114
Figure 1: Structures of diphyllin and its glycosides.
RESULTS AND DISCUSSION
Per-O-acetyl-D-fucosyl bromide was used as starting material in this project.
The synthesis of D-fucose from D-galactose has been reported.[10] We found
that direct iodination of 5 with I2/triphenylphosphine/imidazole[11] and
reduction with tributyl hydride[12] could be successfully applied to prepare
D-fucosyl moiety, and this method provided better yield than the former
procedure (Scheme 1).
Diphyllin was easily prepared for 2-bromo-4,5-dimethoxybenzaldhyde in
five steps in 42.5% yield according to the procedure reported by Charlton
et al.[13] The glycosylation of diphyllin with donor 9 was performed in
-1
.
0.1 mol L NaOH/H2O in the presence of tetra-butylammonium bromide
(TBAB, 1.0 equiv) at 408C to give 10. Subsequently, deacetylation with
K2CO3 in methanol was carried out smoothly to produce target molecule
without destruction of the lactone residue (Sch. 2).
Compounds were evaluated for their cytotoxic activities against three
human cancer cell lines HCT116, MCF-7, and KB using a SRB growth
Scheme 1: Reagents and conditions: a) CH3COCH3, CuSO4, H2SO4, 74.3%; b) I2, imidazole,
Ph3P, PhCH3, 90.8%; c) Bu3SnH, AIBN, PhCH3, 75.7%; d) 80% HOAc, 1208C, then Ac2O, Pyr, 80.9%;
e) HBr-HOAc, DCM, 78.6%.

Synthesis of Per-acetyl D-fucopyranosyl Bromide
115
Scheme 2: Reagents and conditions: a) CHCl3, H2O, TBAB, NaOH, 408C, 80.6%; b) K2CO3,
MeOH, 83.3%.
inhibition assay. IC50 values are summarized in Table 1 and represent the con-
centration inducing a 50% decrease of cell growth after 3 days incubation.
The synthesized analog 4 showed potent biological activities against three
human cancer cell lines. Especially, 4 was more cytotoxic than 1 and 2 to the
MCF-7 cell line, suggesting that the stereochemical orientation of C-4”
hydroxyl group has a significant impact on cytotoxic effect.
EXPERIMENTAL
General Methods
Solvents were purified in the usual way. TLC was performed on precoated
Merck silica Gel 60 F254 plates. Flash chromatography was performed on silica
gel (100–200 mesh, Qingdao, China). Optical rotations were determined with
1
a Perkin-Elmer Model 241 MC polarimeter. H NMR and 13C NMR spectra
were taken on a JEOL JNM-ECP 600 MHz spectrometer with tetramethylsilane
(TMS) as an internal standard, and chemical shifts were recorded in d values.
The high-resolution spectra were obtained on a Q-TOF Global Mass (ESIMS).
1,2:3,4-Di-O-isopropylidene-a-D-galactopyranose (5)
1,2:3,4-Di-O-isopropylidene-a-D-galactopyranose (2) was prepared by acet-
onation of D-galactose,[9] Rf 0.67 (EtOAc:petroleum ether, 1:2), [a]2D0 –55.38 (c
1
3.5, CHCl3), H NMR (CDCl3): d 5.58 (d, 1 H, J ¼ 5.0 Hz, H-1), 4.61 (dd, 1 H,
Table 1: IC50 values (mM) for 1, 2, 4 and diphyllin.
No.
HCT116
MCF-7
KB
1
2
4
0.05
0.9
2.8
0.5
.100
50
0.03
0.9
0.2
2.4
60
Diphyllin
0.06

Z. Yu et al.
116
J ¼ 7.8, 2.3 Hz, H-3), 4.34 (dd, 1 H, J ¼ 5.0, 2.3 Hz, H-2), 4.28 (d, 1 H,
J ¼ 8.3 Hz, H-4), 3.88–3.85 (m, 2 H, H-6a, 6b), 3.75–3.73 (m, 1 H, H-5), 2.19
(brs, 1 H, OH-6), 1.53, 1.46, 1.34, 1.33 (s, each 3 H, CH3), identical to
literature.[9]
1,2:3,4-Di-O-isopropylidene-6-iodo-D-galactopyranose (6)[10]
I2 (2.1 g, 8.3 mmol), Ph3P (2.3 g, 8.7 mmol), and imidazole (1.2 g,
17.6 mmol) were added to the solution of 5 (1.5 g, 5.8 mmol) in toluene
(30 mL). The mixture was stirred for 2 h in an oil bath at 708C. The mixture
was diluted and filtered, and the filter concentrated in vacuo and purified by
silica gel chromatography (EtOAc:petroleum ether, 1:4) to afford 6 as white
solid (1.9 g, 90.8%), Rf 0.76 (EtOAc:petroleum ether, 1:2), [a]2D0 –57.38 (c 1.0,
CHCl3), 1H NMR (CDCl3): d 5.54 (d, 1 H, J ¼ 5.0 Hz, H-1), 4.62 (dd, 1 H,
J ¼ 7.8, 2.3 Hz, H-3), 4.41 (dd, 1 H, J ¼ 7.8, 1.9 Hz, H-4), 4.30 (dd, 1 H,
J ¼ 5.0, 2.3 Hz, H-2), 3.96–3.93 (m, 1 H, H-5), 3.32 (dd, 1 H, J ¼ 9.8, 6.9 Hz,
H-6a), 3.21 (dd, 1 H, J ¼ 9.8, 7.3 Hz, H-6b), 1.54, 1.44, 1.35, 1.33 (s, each 3 H,
CH3).
1,2:3,4-Di-O-isopropylidene-D-fucopyranose (7)[10]
Bu3SnCl (3 g, 9.0 mmol) was dissolved in ether (20 mL); LiAlH4 (150 mg,
3.5 mmol) was added carefully at 08C. The mixture was allowed to stir for 2 h
at rt. Ice water (10 mL) was added, and the mixture was stirred for an
additional 10 min. The organic layer was successively washed with water
(2 ꢀ 20 mL), dried over anhydrous Na2SO4, and evaporated under reduced
pressure to give the Bu3SnH as oil.
The resulted Bu3SnH was dissolved in PhCH3 (20 mL) and 6 (1.8 g,
4.8 mmol) and AIBN (117 mg, 0.7 mmol) was added. The mixture was stirred
for 1 h at 1008C under N2, and then EtOAc (20 mL) was added. The organic
layer was washed with water (2 ꢀ 20 mL), dried over anhydrous Na2SO4,
and evaporated under reduced pressure. The residue was purified by flash
chromatography (EtOAc:petroleum ether, 1:30) to afford 7 as oil (890 mg,
75.7%), Rf ¼ 0.65 (EtOAc:petroleum ether, 1:10), [a]2D0 –35.68 (c 1.0, CHCl3);
1H NMR (CDCl3): d 5.52 (d, 1 H, J ¼ 5.0 Hz, H-1), 4.59 (dd, 1 H, J ¼ 7.8,
2.3 Hz, H-3), 4.29 (dd, 1 H, J ¼ 5.0, 2.3 Hz, H-2), 4.08 (dd, 1 H, J ¼ 7.8,
1.8 Hz, H-4), 3.93–3.89 (m, 1 H, H-5), 1.52, 1.47, 1.35, 1.33 (s, each 3 H,
CH3), 1.26 (d, 3 H, J ¼ 6.4 Hz, CH3).
1,2,3,4-Tetra-O-acetyl-D-fucopyranose (8)[10]
7 (1.1 g, 4.7 mmol) was dissolved in 80% HOAc (20 mL), and stirred for 12 h
at 1108C. The mixture was evaporated under reduced pressure. The residue
was dissolved in dry pyridine (10 mL) and Ac2O (5 mL), and DMAP (20 mg)
was added slowly. The mixture was stirred for 2 h. CH2Cl2 (30 mL) was
added, and the organic layer was washed with 1 M HCl (2 ꢀ 30 mL), saturated

Synthesis of Per-acetyl D-fucopyranosyl Bromide
117
NaHCO3 (2 ꢀ 30 mL), and brine (2 ꢀ 30 mL) and successively dried over
anhydrous Na2SO4 and evaporated under reduced pressure. The residue was
purified by flash chromatography (EtOAc:petroleum ether, 1:3) to give afford
8 (1.25 g, 80.9%, a:b, 4:5), Rf ¼ 0.35 (EtOAc:petroleum ether, 1:3), HRMS
1
calcd for C14H20O9Na 355.1005, found 355.0999; H NMR(CDCl3): b: d 5.68
(d, 1 H, J ¼ 8.3 Hz, H-1), 5.34–5.33 (m, 2-H, H-2, H-3), 5.07 (dd, 1 H,
J ¼ 10.1, 3.2 Hz, H-4), 3.98–3.94 (m, 1 H, H-5), 2.19, 2.11, 2.04, 1.99 (s, each
3 H, OAc), 1.22 (d, 3 H, J ¼ 6.4 Hz, CH3); a: d 6.34 (d, 1 H, J ¼ 3.2 Hz, H-1),
5.30–5.27 (m, 2 H, H-2, H-3), 4.28 (dd, 1 H, J ¼ 13.3, 6.4 Hz, H-4), 4.14–4.10
(m, 1 H, H-5), 2.18, 2.15, 2.09, 2.00 (s, each 3 H, OAc), 1.16 (d, 1 H,
J ¼ 6.4 Hz, CH3).
2,3,4-Tri-O-acetyl-D-fucopyranosyl bromide (9)
8 (1.3 g, 4.0 mmol) was dissolved in dry DCM (10 mL); 40% HBr-HOAc
(2 mL) was added carefully at 08C. The mixture was allowed to stir for 4 h at
rt. DCM (10 mL) was added, and the organic layer was successively washed
with saturated NaHCO3 (2 ꢀ 20 mL) and brine (2 ꢀ 20 mL), dried over anhy-
drous Na2SO4, and evaporated under reduced pressure to give 9 (1.10 g,
78.6%) as a white solid.
2, 3, 4-Tri-O-acetyl-7-O-b-D-fucopyranosyldiphyllin (10)
To the solution of diphyllin (200 mg, 0.53 mmol) and TBAB (171 mg,
0.53 mmol) in CHCl3 (20 mL) was added aqueous 0.1 mol/L NaOH (20 mL).
After stirring for 10 min at 408C, 9 (302 mg, 0.79 mmol) was added, and the
two-phase mixture was stirred for 6 h at 408C. Then CHCl3 (20 mL) was
added and the resulting organic phase was washed with brine (2 ꢀ 20 mL)
and dried over Na2SO4, and the solvent evaporated under reduce pressure.
The residue was purified by flash chromatography (EtOAc:petroleum ether,
1:2) to afford 10 as white solid (278 mg, 80.6%), Rf 0.55 (EtOAc:petroleum
1
ether, 1:1); H NMR (600 MHz, CDCl3): d 7.57 (d, 1 H, J ¼ 1.8 Hz, ArH), 7.06
(s, 1 H, ArH), 6.95 (d, 1 H, J ¼ 7.8 Hz, ArH), 6.82 (dd, 1 H, J ¼ 5.5, 1.4 Hz,
ArH), 6.80–6.78 (m, 1 H, ArH), 6.09 (s, 1 H, OCH2O), 6.05 (d, 1 H,
J ¼ 1.4 Hz, OCH2O), 5.68 (dd, 1 H, J ¼ 10.6, 8.2 Hz, H-1”), 5.34 (d, 1 H,
J ¼ 3.2 Hz, H-4”), 5.15–5.13 (m, 2 H, H-2”, H-3”), 5.50 (dd, 1 H, J ¼ 14.7,
1.9 Hz, H-9a), 5.41 (dd, 1 H, J ¼ 14.7, 3.7 Hz, H-9b), 4.08 (s, 3 H, OCH3), 3.81
(s, 3 H, OCH3), 2.27, 2.09, 2.05 (each 3 H, 3 ꢀ OAc), 1.29 (dd, 1 H, J ¼ 6.4,
1.4 Hz, CH3).
7-O-b-D-fucopyranosyldiphyllin (4)
The solid 10 (223 mg, 0.32 mmol) was dissolved in CH3OH (20 mL), and
then K2CO3 (100 mg, 0.72 mmol) was added. After stirring for 30 min at rt,
the solution was neutralized with 1 mol/L HCl, CHCl3 (20 mL) was added,
the resulting organic phase was washed with brine (2 ꢀ 20 mL) and dried

Z. Yu et al.
118
over Na2SO4, and the solvent evaporated under reduce pressure. The residue
was purified by flash chromatography (CHCl3:MeOH, 10:1) to afford 4 as a
white solid (150 mg, 83.3%), Rf 0.40 (CHCl3:MeOH, 10:1), [a]2D5 ¼ –57.38
1
(c1.00, CH2Cl2); H NMR (600 MHz, DMSO-d6) : d 8.18 (d, 1 H, J ¼ 2.8 Hz,
ArH), 7.03 (dd, 1 H, J ¼ 7.8, 1.9 Hz, ArH), 6.98 (d, 1 H, J ¼ 3.2 Hz, ArH),
6.93 (dd, 1 H, J ¼ 17.4, 1.9 Hz, ArH), 6.81–6.78 (m, 1 H, ArH), 6.12 (s, 2 H,
OCH2O), 5.77 (brs, 1 H, OH-2”), 5.52 (dd, 1 H, J ¼ 14.8, 3.7 Hz, H-9a), 5.47
(d, 1 H, J ¼ 14.8 Hz, H-9b), 4.96 (brs, 1 H, OH-3”), 4.71 (d, 1 H, J ¼ 7.7 Hz,
H-1”), 4.68 (brs, 1 H, OH-4”), 3.94 (s, 3 H, OCH3), 3.76–3.72 (m, 1 H, H-2”),
3.66 (s, 3 H, OCH3), 3.63–3.60 (m, 1 H, H-5”), 3.47–3.46 (m, 1 H, H-4”),
3.43–3.42 (m, 1 H, H-3”), 1.18 (dd, 3 H, J ¼ 6.4, 1.2 Hz, CH3); 13C NMR (150
MHz, DMSO-d6): d 169.1 (C55O), 151.3 (C-5), 149.9 (C-4), 146.9 (C-4’), 146.8
(C-3’), 145.0 (C-7), 134.8 (C-7’), 129.9 (C-1), 129.7 (C-8), 128.2 (C-1’), 126.9
(C-2), 123.5 (C-6’), 118.6 (C-8’), 110.8 (C-2’), 107.9 (C-3), 105.7 (C-1”), 105.3
(C-5), 101.8 (C-6), 101.1 (OCH2O), 73.2 (C-3”), 70.8 (C-4”), 70.5 (C-2”), 70.4
(C-5”), 67.1 (C-9), 55.7 (OCH3), 55.1 (OCH3), 16.5 (CH3); HRMS calcd for
C27H27O11 527.1553, found 527.1576.
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