The first total synthesis of apigenin 7-O-β-D-cellobiosyl-4′-O- β-D-glucopyranoside isolated from Salvia uliginosa

Article abstract of DOI:10.1080/14786419.2012.686908

The first total synthesis of apigenin 7-O-β-D-cellobioside (5) and apigenin 7-O-β-D-cellobiosyl-4′-O-β-D-glucopyranoside (8), which were isolated from petals of Salvia patens and Salvia uliginosa, were achieved in four and six steps and 76% and 57%, respe

Full text of DOI:10.1080/14786419.2012.686908

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Natural Product Research: Formerly
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The first total synthesis of apigenin
7-O-β-D-cellobiosyl-4′-O-β-D-
glucopyranoside isolated from Salvia
uliginosa
Fatih Sonmez a , Mehmet Nebioglu a , Senol Besoluk b , Mustafa
Arslan a , Mustafa Zengin a & Mustafa Kucukislamoglu a
a Faculty of Art and Sciences, Department of Chemistry, Sakarya
University, Sakarya 54140, Turkey
b Faculty of Education, Department of Science Education, Sakarya
University, Sakarya 54300, Turkey
Version of record first published: 23 May 2012.
To cite this article: Fatih Sonmez, Mehmet Nebioglu, Senol Besoluk, Mustafa Arslan, Mustafa Zengin
& Mustafa Kucukislamoglu (2012): The first total synthesis of apigenin 7-O-β-D-cellobiosyl-4′-O-β-D-
glucopyranoside isolated from Salvia uliginosa , Natural Product Research: Formerly Natural Product
Letters, DOI:10.1080/14786419.2012.686908
To link to this article: http://dx.doi.org/10.1080/14786419.2012.686908
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Natural Product Research
2012, 1–8, iFirst
The first total synthesis of apigenin 7-O-b-D-cellobiosyl-40-O-b-D-
glucopyranoside isolated from Salvia uliginosa
Fatih Sonmeza, Mehmet Nebioglua, Senol Besolukb, Mustafa Arslana, Mustafa Zengina
a
*
and Mustafa Kucukislamoglu
aFaculty of Art and Sciences, Department of Chemistry, Sakarya University, Sakarya 54140,
Turkey; Faculty of Education, Department of Science Education, Sakarya University,
Sakarya 54300, Turkey
b
(Received 6 October 2011; final version received 11 March 2012)
The first total synthesis of apigenin 7-O-ꢀ-D-cellobioside (5) and apigenin
7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glucopyranoside (8), which were isolated from
petals of Salvia patens and Salvia uliginosa, were achieved in four and six steps
and 76% and 57%, respectively, overall yield, from naringenin (1). The total
synthesis contained two-glycosylation, acetylation, oxidation, selective deacetyla-
tion and deprotection steps. Although this route contained six steps, the targeted
compounds were obtained with higher yields and easier purifications than other
synthetic methods.
Keywords: flavonoid glycoside; apigenin 7-O-ꢀ-D-cellobioside; apigenin
7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glucopyranoside; total synthesis
1. Introduction
Flavonoid glycosides, as well as their aglycones, are widely distributed in the plant
kingdom (Harborne, 1988, 1994) and have significant biological activities such as
antitumour, antimicrobial and radical-scavenging properties (Fraser-Reid & Tatsuta,
2001; Rice-Evans, 1997). Sugar moiety usually is found at the C7 position of flavonoid
O-glycosides, but rarely found at the C4 position. Despite their importance, synthesis of
flavonoid glycosides was extremely limited (Bouktaib, Atmani, & Rolando, 2002;
Caldwell, Crozier, & Hartley, 2000; Caldwell, Petersson, Farrugia, Mullen, & Hartley,
2006; Du, Wei, & Linhardt, 2003, 2004; Elhabiri, Figueiredo, Fougerousse, & Brouillard,
1995; Iacobucci & Sweeny, 1983; Kondo et al., 2006; Krishnamutry, Krishnamoorthy, &
Seshadri, 1963; Li, Han, & Yu, 2003; Maloney & Hecht, 2005; Murakami, Robertson, &
Robinson, 1931; Robertson & Robinson, 1927). There are two critical ways on the
synthesis of glycosyl flavonoids. The first one is the synthesis of the flavonoid skeleton via
cyclisation after glycosylation. The second one is direct glycosylation of the flavonoid
skeleton and it is thought that the nucleophilicity of the phenolic hydroxyl group at 7-OH
is much higher than that at 40-OH in flavonoids (Farkas, Wolfner, Nogradi, Wagner, &
Horhammer, 1968; Nogradi, Farkas, Wagner, & Horhammer, 1967). Actually, direct
¨
glycosylation of flavanone skeleton with excess sugar halide and silver carbonate gave only
¨
7-O-glycosides.
*Corresponding author. Email: mustafak@sakarya.edu.tr
ISSN 1478–6419 print/ISSN 1478–6427 online
ß 2012 Taylor & Francis
http://dx.doi.org/10.1080/14786419.2012.686908
http://www.tandfonline.com

2
F. Sonmez et al.
6'''
3'
OH
5'''O
2'''
2'
1'
4'
5'
6''
OR
OH
5''O
4'''
4''
1
HO
8
O
2
O
O
9
7
HO
1'''HO
3'''
1''
OH
2''
3''
6'
OH
6
4
3
10
5
OH
O
5: R= H,8: R=β-D-Glc
Figure 1. Structure of apigenin 7-O-ꢀ-D-cellobioside (5) and apigenin 7-O-ꢀ-D-cellobiosyl-4’-O-ꢀ-D-
glucopyranoside (8).
OAc
OAc
OH
ii
OH
OAc
OAc
OAc
O
O
AcO
AcO
AcO
AcO
O
O
O
AcO
O
O
O
HO
O
O
O
AcO
O
O
O
OAc
OAc
i
OAc
OAc
OH
2
OH
OAc
3
1
OH
O
OAc
OH
OAc
OH
OAc
O
HO
HO
AcO
AcO
O
O
iii
iv
O
HO
O
AcO
O
O
O
O
O
OH
OAc
OH
OAc
OH
OAc
O
5
4
Figure 2. Synthesis of apigenin 7-O-cellobioside (6): (i) Ag2CO3/quinoline, hepta-O-acetyl-
cellobiosylbromide, 86%; (ii) Ac2O/H2SO4, 93%; (iii) NBS, dibenzoylperoxide/CCl4, 97%; and
(iv) CH3O– Kþ/CH3OH/CHCl3, 98%.
OAc
OAc
OH
OAc
AcO
OAc
OAc
O
OAc
O
O
AcO
AcO
O
O
AcO
AcO
O
O
O
O
O
AcO
O
O
O
O
AcO
AcO
OAc
i
OAc
ii
4
OAc
OAc
OH
6
OH
7
OH
OH
HO
O
OH
OH
O
O
HO
HO
O
O
O
O
HO
HO
iii
OH
OH
OH
8
O
Figure 3. Synthesis of apigenin-7,4’-di-O-glycosides (8): (i) NH4OAc/H2O/MeOH/THF,
91%; (ii)Ag2CO3/quinoline, tetra-O-acetyl-glycosylbromide, 84%; and (iii) CH3O– Kþ/CH3OH/
CHCl3, 94%.
In this study, we focused our attention on the first total synthesis of apigenin 7-O-ꢀ-D-
cellobioside (5) and apigenin 7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glucopyranoside (8), isolated
from flower of Salvia patens and Salvia uliginosa (Veicth, Grayer, Irwin, & Takeda, 1998;
Figure 1) via direct glycosylation of naringenin (1).
2. Results and discussion
The synthesis of the target compounds was performed by reactions illustrated in
Figures 2 and 3. First, naringenin (1) was glycosylated at C7-OH with hepta-O-acetyl-
cellobiosylbromide in the presence of Ag2CO3 in quinoline under Koenigs–Knorr

Natural Product Research
3
conditions (Farkas et al., 1968) to give 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-naringenin (2).
Compound 2 was oxidised with DDQ in 1,4-dioxane (Oyama & Kondo, 2004), but the
yield of the reaction was very low at the end of column chromatography. Oxidation of
compound 2 was performed with NBS in CCl4 to improve the yield (Looker & Holm,
1959). The best results were obtained after acetylation of naringenin hydroxyl groups in
this step. For this purpose, compound 2 was acetylated with acetic anhydride in the acidic
medium. Then, compound 3 was oxidised to compound 4 with NBS in CCl4 in high yields
(97%) (Looker & Holm, 1959). This method has several advantages such as high yields
and no further purification, from oxidation of flavonone acetates with DDQ in
1,4-dioxane (Oyama & Kondo, 2004) and I2 in pyridine (Chen, Huang, Lian, & Lin,
2009). Finally, deacetylation of compound 4 was carried out with KOCH3 in MeOH–
CHCl3 (1 : 1) at room temperature and compound 5 was obtained in high yields. The
1H-NMR spectrum of compound 5 contained two distinctive groups of resonances. Those
at ꢁ 12.97 (s, 5-OH), 10.48 (s, 40-OH), 7.94 (d, J ¼ 8.4 Hz, H-20,60), 6.95(d, J ¼ 8.2 Hz,
H-30,50), 6.84 (s, H-3), 6.82 (s, H-8) and 6.46 (s, H-6), represented aromatic protons, and
were consistent with the compound 5. The second group, appearing between ꢁ 3.07 and
5.60 ppm, comprised both non-exchangeable and exchangeable resonances of glycosidic
origin. Two anomeric proton resonances were noted at ꢁ 4.33 and 5.17 ppm, and used as
the starting point for the complete assignment of the non-exchangeable glycosyl
resonances.
On the other hand, apigenin 7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glucopyranoside (8) was
synthesised from compound 4 (Figure 3). The selective deacylation of compound 4 was
done with NH4Ac in H2O–MeOH–THF (1 : 4 : 8) (Ramesh, Mahender, Ravindranath,
& Das, 2003) for the glycosylation of the phenolic hydroxyl group at 40-OH.
Compound 6 was glycosylated with tetra-O-acetyl-glycosylbromide in the presence of
Ag2CO3 in quinoline (Farkas et al., 1968; Figure 3) afforded compound 7. Desired
product compound 8 was obtained after deacetylation with KOCH3 in MeOH–CHCl3
1
(1 : 1) at room temperature. The H-NMR spectrum of compound 8 was more complex
than the corresponding spectra of compound 5, but contained features common to
them both. Aromatic and phenolic resonances at ꢁ 12.87 (s, 5-OH), 8.05 (d, J ¼ 8.5 Hz,
H-20,60), 7.18 (d, J ¼ 8.5 Hz, H-30,50), 6.98 (s, H-3), 6.86 (s, H-8) and 6.45 (s, H-6), were
consistent with an apigenin derivative substituted at the 40 position. Three anomeric
protons were resonanced at ꢁ 5.16 (d, J ¼ 7.0 Hz), 5.02 (d, J ¼ 6.5 Hz) and 4.47
(d, J ¼ 7.9 Hz). The results confirmed the synthesis of apigenin 7-O-ꢀ-D-cellobiosyl-40-O-
ꢀ-D-glucopyranoside (8).
Additionally, anomeric configurations are assigned from the magnitude of J1,2, with
values of 7–9 Hz for a ꢀ-configuration and 2–4 Hz indicative coupling of ꢂ-anomers for
1
glycosides in H-NMR spectrum (Bubb, 2003; Harborne, 1994). The chemical shift of an
anomeric carbon in an ꢂ-linkage (ꢁ 90–93) is in general less than that of an anomeric
carbon in a ꢀ-linkage (ꢁ 99–103; Bubb, 2003; Harborne, 1994). The coupling constant of
the anomeric proton (J ¼ 7.3 Hz) and the chemical shift of C-100 (ꢁ 100.1) confirmed the
ꢀ-linkage of cellobiose for compound 5. Similarly, the coupling constants of anomeric
protons (J ¼ 7.0 Hz and J ¼ 7.9 Hz) and the chemical shift of C-100 and C-10000 (ꢁ 100.1 and
ꢁ 100.4) confirmed the ꢀ-linkage of cellobiose and glucose for compound 8.
3. Experimental
3.1. General
Melting points were taken on a Barnstead Electrothermal 9200. IR spectra were measured
1
on a SHIMADZU Prestige-21 (200 VCE) spectrometer. H- and 13C-NMR spectra were

4
F. Sonmez et al.
1
measured on spectrometer VARIAN Infinity Plus at 300 and 75 Hz, respectively. H- and
13C-chemical shifts are referenced to the internal deuterated solvent. Mass spectra were
obtained using MICROMASS Quattro LC–MS–MS spectrometer. Flash column
chromatography was performed using Merck silica gel 60 (230–400 mesh ASTM).
Solvents were dried with the standard methods. All chemicals were purchased from Merck,
Alfa Easer, Sigma–Aldrich and Fluka.
3.2. Synthetic procedure and data
3.2.1. Heptaacetyl-ꢀ-D-cellobiosyl bromide and tetraacetyl-ꢀ-D-glycosyl bromide
Heptaacetyl-ꢀ-D-cellobiosyl bromide and tetraacetyl-ꢀ-D-glycosyl bromide were prepared
by the literature (Redemann & Niemann, 1955).
3.2.2. 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-naringenin (2)
A solution of heptaacetyl-ꢀ-D-cellobiosyl bromide (2.360 g, 3.37 m mol), Ag2CO3 (0.928 g,
3.37 m mol) and naringenin 1 (0.612 g, 2.25 m mol) in quinoline (7 mL) was stirred for 3 h at
room temperature. After being poured into 20 mL CH3OH, the solution was Eltered
through a short pad of silica gel and evaporated in vacuo. The residue was dissolved into
100 mL EtOAc and washed successively with 1 N HCl (2 ꢀ 50 mL) and brine (2 ꢀ 50 mL),
and dried over anhydrous MgSO4. After evaporation, the resulting crude product was
puriEed by Fash column chromatography (hexane–EtOAc 1 : 1) to afford 2 (yield 86%,
1.72 g) as a yellowish foam.
IR (ꢃmax, cmꢁ1): 1743, 1643, 1367, 1213, 1170, 1035 cmꢁ1 1H-NMR (300 MHz,
;
CDCl3): ꢁ 1.99 (3H, s), 2.01 (3H, s), 2.02 (3H, s), 2.05 (3H, s), 2.06 (3H, s), 2.07 (3H, s),
2.10 (3H, s), 2.77 (1H, d, J ¼ 17.3 Hz), 3.09 (1H, t, J ¼ 17.2 Hz), 3.67–3.85 (3H, m), 4.03–
4.14 (2H, m), 4.39 (1H, dd, J ¼ 4.4, 4.1 Hz), 4.51 (2H, d, J ¼ 8.5 Hz), 4.92–5.35 (7H, m),
6.08 (2H, dd, J ¼ 3.2, 1.2 Hz), 6.59 (1H, s), 6.89 (2H, d, J ¼ 8.5 Hz), 7.29 (2H, d,
J ¼ 8.5 Hz), 11.92 (1H, s); 13C-NMR (75 MHz, CDCl3): ꢁ 20.77 (ꢀ3), 20.90 (ꢀ2), 21.07
(ꢀ2), 43.38, 61.73, 62.04, 67.87, 70.17, 71.04, 71.72, 72.13, 72.57, 73.00, 73.31, 79.50, 96.29,
97.67, 100.98, 104.44, 115.89, 128.22, 129.63, 139.64, 157.31, 163.10, 163.94, 164.47,
169.62, 169.72, 169.85, 170.24, 170.55, 170.82, 170.91, 197.01; MS: Calcd for C41H46O22
[M þ H]þ 891.25, found 891.26.
3.2.3. 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-5,40-diacetyl-naringenin (3)
To a solution of 2 (0.890 g, 1.0 m mol) in acetic anhydride (3 mL), two drops of
concentrated H2SO4 were added at ice bath. After stirring for 3 h at room temperature,
the reaction mixture was poured into crushed ice. The product was filtered, washed
with cold water (1 L) and dried in vacuum to afford 3 (yield 93%, 0.906 g) as a white solid;
m.p. 248–250ꢂC.
IR (ꢃmax, cmꢁ1): 1745, 1618, 1367, 1217, 1168, 1037 cmꢁ1 1H-NMR (300 MHz,
;
CDCl3): ꢁ 1.99 (3H, s), 2.02 (3H, s), 2.04 (2ꢀ3H, s), 2.05 (3H, s), 2.06 (3H, s), 2.10 (3H, s),
2.33 (3H, s), 2.38 (3H, s), 2.74 (1H, dd, J ¼ 2.9, 2.6 Hz), 3.02 (1H, t, J ¼ 13.7 Hz), 3.67 (1H,
dd, J ¼ 2.1, 2.3 Hz), 3.81–3.83 (2H, m), 4.02–4.11 (2H, m), 4.39 (1H, dd, J ¼ 4.4, 4.1 Hz),
4.49–4.55 (2H, m), 4.94 (1H, t, J ¼ 8.2 Hz) 5.04–5.31 (5H, m), 5.45 (1H, d, J ¼ 13.4 Hz),
6.34 (1H, d, J ¼ 2.3 Hz), 6.51 (1H, d, J ¼ 2.3 Hz), 7.15 (2H, d, J ¼ 8.3 Hz), 7.45 (2H, d,
J ¼ 8.4 Hz); 13C-NMR (75 MHz, CDCl3): ꢁ 20.74 (ꢀ2), 20.82 (ꢀ2), 20.91 (ꢀ2), 20.95,
21.34, 21.40, 45.31, 61.67, 62.03, 67.77, 71.05, 71.67, 72.20, 72.50, 73.02, 73.40, 79.40,
97.82, 101.07, 102.40, 102.60, 106.49, 109.62, 122.34, 127.71, 135.78, 151.20, 151.90,
162.20, 164.06, 169.34, 169.60, 169.66, 169.74, 169.82, 169.99, 170.51 (ꢀ2), 170.78, 188.90;
MS: Calcd for C45H50O24Na [M þ Na]þ 997.86, found 997.45.

Natural Product Research
3.2.4. 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-5,40-diacetyl-apigenin (4)
5
In a two-necked flask equipped with dropping funnel, and side arm connected to a cooled
receiving vessel, were placed 3 (0.974 g, 1.0 m mol), NBS (0.531 g, 3.0 m mol), a few grains
(ca. 1 ma.) of dibenzoyl peroxide, and 50 mL of carbon tetrachloride. After 15 min of
heating, bromine evolution began. The heat was increased so that solvent and bromine
distilled from the side arm and collected in the receiver. Fresh solvent was added through
the dropping funnel, and dibenzoyl peroxide was added as needed to maintain bromine
evolution. The reaction was completed in 2 h. The volume of liquid in the reaction vessel
was reduced to 25 mL and the mixture cooled to 0ꢂC. The precipitated solid was removed
by filtration and washed with hot water (100 mL). After drying, the residue recrystallised
from methanol to afford 4 (yield 97%, 0.943 g) as a beige solid; m.p. 272–274ꢂC.
IR (ꢃmax, cmꢁ1): 1745, 1637, 1369, 1209, 1170, 1041 cmꢁ1 1H-NMR (300 MHz,
;
CDCl3): ꢁ 2.00 (3H, s), 2.03 (3H, s), 2.05 (3H, s), 2.06 (3H, s), 2.07 (3H, s), 2.08 (3H, s),
2.11 (3H, s), 2.35 (3H, s), 2.44 (3H, s), 3.69 (1H, d, J ¼ 7.9 Hz), 3.88–3.90 (2H, m),
4.04–4.16 (2H, m), 4.38–4.43 (1H, dd, J ¼ 4.1, 12.3 Hz), 4.53–4.58 (2H, m), 4.96 (1H, t,
J ¼ 8.3 Hz), 5.06–5.30 (5H, m), 6.59 (1H, s), 6.67 (1H, d, J ¼ 1.8 Hz), 6.98 (1H, d,
J ¼ 1.8 Hz), 7.26 (2H, d, J ¼ 8.5 Hz), 7.87 (2H, d, J ¼ 8.5 Hz); 13C-NMR (75 MHz, CDCl3):
ꢁ ¼ 20.75 (ꢀ2), 20.82 (ꢀ3), 20.94 (ꢀ2), 21.35, 21.43, 61.70, 62.13, 67.83, 71.18, 71.75, 72.25,
72.49, 73.04, 73.38, 76.52, 97.95, 101.12, 102.70, 108.75, 109.58, 112.94, 122.63, 127.77,
128.85, 150.84, 153.47, 158.55, 160.21, 161.74, 169.24, 169.35, 169.59, 169.74, 169.89,
169.99, 170.44, 170.49, 170.77, 176.46; MS: Calcd for C45H48O24 [M þ H]þ 973.25,
found 973.41.
3.2.5. 7-O-ꢀ-D-cellobiosyl-apigenin (5)
To a solution of 4 (0.194 g, 0.2 m mol) in a mixture of CH3OH (3 mL) and CHCl3 (3 mL),
KOCH3 (0.056 g, 0.8 m mol) was added at room temperature. After stirring for 2 h, the
reaction mixture was neutralised with 1 N HCl, Eltered, and filtrate was evaporated in
vacuum. The residue recrystallised from EtOH to afford 5 (yield 98%, 0.116 g) as a yellow
solid; m.p. 284–286ꢂC.
1
IR (ꢃmax, cmꢁ1): 3358, 1656, 1602, 1246, 1175, 1072, 1029 cmꢁ1; H-NMR (300 MHz,
DMSO-d6): ꢁ 3.07–3.34 (5H, H-200, H-2000-5000, m), 3.61–3.77 (4H, H-500-600, H-6000, m), 4.33
(1H, H-1000, d, J ¼ 7.3), 4.72–4.77 (2H, 2ꢀOH, m), 4.92 (1H, OH, s), 5.08–5.17 (3H, H-100,
2ꢀOH, m), 5.33 (1H, d, OH, J ¼ 4.4 Hz), 5.60 (1H, d, OH, J ¼ 5.0 Hz), 6.46 (1H, H-6, s),
6.82 (1H, H-8, s), 6.84 (1H, H-3, s), 6.95 (2H, H-30, H-50, d, J ¼ 8.2 Hz), 7.94 (2H, H-20,
0
0
0
H-6 , d, J ¼ 8.4 Hz), 10.48 (1H, C4 -OH, s), 12.97 (1H, C5 -OH, s); signals of three protons
(H-300, H-400 and H-6000) were overlapped with the signals of H2O; 13C-NMR (75 MHz,
DMSO-d6): ꢁ 60.58 (C-600), 61.72 (C-6000), 70.70 (C-4000), 73.46 (C-200), 73.95 (C-2000), 75.44
(C-300), 75.74 (C-500), 77.14 (C-3000), 77.49 (C-5000), 80.34 (C-400), 95.52 (C-8), 99.95 (C-6),
100.10 (C-100), 103.80 (C-3, C-1000), 106.03 (C-10), 116.68 (C-30, C-50), 121.67 (C-10), 129.31
(C-20, C-60), 157.59 (C-40), 161.81 (C-9), 162.04 (C-5), 163.47 (C-2), 164.93 (C-7), 182.69
(C-4); MS: Calcd for C27H30O15K [M þ K]þ 633.12, found 633.11.
3.2.6. 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-apigenin (6)
To a solution of 4 (0.972 g, 1.0 m mol) in H2O:MeOH:THF (1 : 4 : 8, 20 mL), NH4OAc
(1.232 g, 16.0 m mol) was added. The resulting mixture was stirred at 50ꢂC. After 24 h, the
mixture was concentrated and the residue was extracted with EtOAc (3 ꢀ 25 mL).
Evaporation of the solvent afforded the deprotected product recrystallised from MeOH to
afford 6 (yield 91%, 0.808 g) as a beige solid; m.p. 201–203ꢂC.

6
F. Sonmez et al.
IR (ꢃmax, cmꢁ1): 3433, 1739, 1604, 1367, 1222, 1174, 1035 cmꢁ1; H-NMR (300 MHz,
1
DMSO-d6): ꢁ 1.91 (3H, s), 1.95 (3H, s), 1.96 (3H, s), 1.97 (3H, s), 2.00 (3H, s), 2.01 (3H, s),
2.06 (3H, s), 3.84–4.27 (6H, m), 4.39 (1H, d, J ¼ 11.1 Hz), 4.65 (1H, t, J ¼ 9.4 Hz), 4.84–
4.91 (2H, m), 4.99 (1H, t, J ¼ 8.2 Hz) 5.26 (1H, dd, J ¼ 12.9, 9.4 Hz), 5.27 (1H, dd, J ¼ 6.2,
9.4 Hz), 5.65 (1H, d, J ¼ 7.9 Hz), 6.40 (1H, d, J ¼ 1.7 Hz), 6.75 (1H, d, J ¼ 1.6 Hz), 6.88
(1H, s), 6.91 (2H, d, J ¼ 8.5 Hz), 7.93 (2H, d, J ¼ 8.6 Hz), 10.41 (1H, s), 13.00 (1H, s);
13C-NMR (75 MHz, DMSO-d6): ꢁ 20.91 (ꢀ2), 21.04 (ꢀ2), 21.12 (ꢀ2), 21.19, 62.14, 62.65,
68.33, 71.14, 71.29, 71.82, 72.60, 72.82 (ꢀ2), 76.95, 95.74, 96.89, 99.88, 100.21, 103.83,
106.52, 116.65, 121.55, 129.29, 157.49, 162.00, 162.12, 165.07, 169.73, 169.89, 170.13 (ꢀ2),
170.29, 170.72, 170.85, 182.71; MS: Calcd for C41H44O22 [M þ H]þ 889.23, found 889.39.
3.2.7. 7-O-(Heptaacetyl-ꢀ-D-cellobiosyl)-40-O-(tetraacetyl-ꢀ-D-glycosyl)-apigenin (7)
According to the procedure described for 2, 6 (0.888 g, 1.0 m mol) was glycosylated with
tetraacetyl-ꢀ-D-glycosyl bromide (1.03 g, 2.5 m mol) to afford 7 (yield 84%, 1.02 g) as a
yellowish solid; m.p. 307–309ꢂC.
IR (ꢃmax, cmꢁ1): 1741, 1595, 1367, 1217, 1176, 1033 cmꢁ1 1H-NMR (300 MHz,
;
DMSO-d6): ꢁ 1.90 (3H, s), 1.91 (3H, s), 1.96 (2ꢀ3H, s), 1.97 (2ꢀ3H, s), 2.00 (4ꢀ3H, s), 2.05
(3H, s), 3.84–4.30 (9H, m), 4.40 (1H, d, J ¼ 11.1 Hz), 4.66 (1H, t, J ¼ 8.8 Hz), 4.84–4.91
(2H, m), 4.97–5.12 (3H, m), 5.22–5.30 (2H, m), 5.41 (1H, t, J ¼ 9.7 Hz), 5.66 (1H, d,
J ¼ 7.6 Hz), 5.75 (1H, d, J ¼ 7.9 Hz), 6.43 (1H, d, J ¼ 1.5 Hz), 6.79 (1H, d, J ¼ 1.5 Hz), 7.03
(1H, s), 7.16 (2H, d, J ¼ 8.8 Hz), 8.08 (2H, d, J ¼ 8.8 Hz), 12.89 (1H, s); 13C-NMR
(75 MHz, DMSO-d6): ꢁ 20.60 (ꢀ3), 20.85, 20.92 (ꢀ2), 21.02 (ꢀ2), 21.11 (ꢀ2), 21.19, 62.26,
62.67, 68.30, 68.59, 71.22 (ꢀ3), 71.66 (ꢀ2), 71.83, 72.57 (ꢀ2), 72.83 (ꢀ2), 76.95, 95.89,
96.85, 97.01, 99.70, 100.22, 104.64, 106.64, 117.24, 125.51, 129.17, 157.55, 159.84, 162.00,
162.35, 164.11, 169.73, 169.81, 169.89 (ꢀ2), 170.02, 170.15, 170.31 (ꢀ2), 170.69, 170.76,
170.88, 182.85; MS: calcd for C55H62O31 [M þ H]þ 1219.33, found 1219.58.
3.2.8. 7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glycosyl-apigenin (8)
According to the procedure described for 5, 7 (0.244 g, 0.2 m mol) was deacetylated
with KOCH3 (0.056 g, 0.8 m mol) to afford 8 (yield 94%, 0.142 g) as a white solid;
m.p. 196–198ꢂC.
1
IR (ꢃmax, cmꢁ1): 3257, 1726, 1604, 1242, 1176, 1070, 1029 cmꢁ1; H-NMR (300 MHz,
CD3OD): ꢁ 3.32–3.44 (11H, H-2000-5000, H-40000, 6ꢀOH, m), 3.49–3.56 (5H, H-200, H-20000-30000,
H-50000, OH, m), 3.64–3.74 (7H, H-300-400, H-6000, H-60000, 3ꢀOH, m), 3.88–3.92 (6H, H-500-600,
1
H-6000, H-60000, OH, m), 4.47 (1H, H-1000, d, J ¼ 7.9 Hz); H-NMR (300 MHz, DMSO-d6):
ꢁ 5.02 (1H, H-10000, d, J ¼ 6.5 Hz), 5.16 (1H, H-100, d, J ¼ 7.0 Hz), 6.45 (1H, H-6, s), 6.86
(1H, H-8, s), 6.98 (1H, H-3, s), 7.18 (2H, H-30, H-50, d, J ¼ 8.5 Hz), 8.05 (2H, H-20, H-60, d,
13
J ¼ 8.5 Hz), 12.87 (1H, C5-OH, s); C-NMR (75 MHz, DMSO-d6): ꢁ 60.50 (C-600), 61.24
(C-60000), 61.67 (C-6000), 70.25 (C-40000), 70.67 (C-4000), 73.44 (C-200), 73.80 (C-20000), 73.97
(C-2000), 75.44 (C-300), 75.73 (C-500), 77.17 (C-3000, C-30000), 77.47 (C-5000), 77.80 (C-50000), 80.30
(C-400), 95.54 (C-8), 99.91 (C-100), 100.23 (C-6), 100.39 (C-10000), 103.79 (C-1000), 104.73 (C-3),
106.12 (C-10), 117.25 (C-30), 124.39 (C-10), 128.89 (C-20), 157.65 (C-40), 161.10 (C-9),
161.77 (C-5), 163.55 (C-2), 164.27 (C-7), 182.79 (C-4); MS: Calcd for C33H40O20.K
[M þ K]þ 795.18, found 795.04.
4. Conclusions
In summary, the first total synthesis of apigenin 7-O-ꢀ-D-cellobioside (5) and apigenin
7-O-ꢀ-D-cellobiosyl-40-O-ꢀ-D-glucopyranoside (8) was successfully carried out from

Natural Product Research
7
naringenin (1), in high overall yields, 76% and 57%, respectively. Although this route
contained six steps, the targeted compounds were obtained with higher yields and easier
purifications than other synthetic methods.
Acknowledgements
We gratefully acknowledge The Scientific and Technological Research Council of Turkey
(TUBITAK) for the financial support of this research granted 105T251.
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