Three new glycosides from Viburnum plicatum THUNB. var. tomentosum MIQ

Article abstract of DOI:10.1002/hlca.200900232

Three new glycosides, 7-O-tigloylsecologanol (1), 7-O-tigloylsecologanolic acid (2), and 3'-O-[(2S)-2-methylbutanoyl]henryoside (3), together with seven known ones, were isolated from the leaves of Viburnum plicatum Thunb. var. tomentosum Miq. Their structures were established on the basis of spectral and chemical data.

Full text of DOI:10.1002/hlca.200900232

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Helvetica Chimica Acta – Vol. 93 (2010)
Three New Glycosides from Viburnum plicatum Thunb. var.
tomentosum Miq.
by Koichi Machida, Hitomi Sagawa, Rie Onoguchi, and Masao Kikuchi*
Department of Molecular Structural Analysis, Tohoku Pharmaceutical University, 4-4-1 Komatsushima,
Aoba-ku, Sendai, Miyagi 981-8558, Japan
(phone: þ 81-22-2344181; fax: þ 81-22-2752013; e-mail: mkikuchi@tohoku-pharm.ac.jp)
Three new glycosides, 7-O-tigloylsecologanol (1), 7-O-tigloylsecologanolic acid (2), and 3’-O-[(2S)-
2-methylbutanoyl]henryoside (3), together with seven known ones, were isolated from the leaves of
Viburnum plicatum Thunb. var. tomentosum Miq. Their structures were established on the basis of
spectral and chemical data.
Introduction. – The deciduous shrub Viburnum plicatum Thunb. var. tomentosum
Miq. (Caprifoliaceae) is widely distributed in Japan and China. This plant has been
´
´
`
utilized in traditional Chinese medicine (Chinese name, hu die shu) for lymphadenitis,
ringworm, and infantile tantrum [1]. In a continuation of our investigation of the
chemical constituents from plants of the genus Viburnum species [2 – 9], we have now
examined the chemical constituents of the leaves of V. plicatum Thunb. var.
tomentosum Miq. As far as we know, there is no report regarding the chemical
constituents of this plant. In this article, we describe the isolation and structure
elucidation of three new glycosides, named 7-O-tigloylsecologanol1) (1), 7-O-
tigloylsecologanolic acid1) (2), and 3’-O-[(2S)-2-methylbutanoyl]henryoside1) (3),
together with seven known ones, which were isolated from the leaves of this plant. This
article deals with the structural elucidation and identification of these compounds.
Results and Discussion. – The MeOH extract of the leaves of V. plicatum Thunb.
var. tomentosum Miq. was partitioned with CHCl3, AcOEt, BuOH, and H2O. The
BuOH- and AcOEt-soluble fractions were each subjected to separation by a
combination of chromatographic procedures. From the BuOH-soluble fraction,
compounds 1 – 3 and 42) were isolated, while compounds 5 – 102) were isolated from
the AcOEt-soluble fraction. The known compounds 4 – 102) were identified as (4R)-a-
terpineol O-b-d-glucopyranoside2) (4) [10], (7S,8R)-dihydrodehydrodiconiferyl alco-
hol 9-O-b-d-glucopyranoside2) (5) [11], (7R,8S)-dihydrodehydrodiconiferyl alcohol 9-
O-b-d-glucopyranoside2) (6) [12], quercetin 3-O-robinobioside2) (7) [13], quercetin 3-
O-rutinoside2) (8) [13], kaempferol 3-O-robinobioside2) (9) [13], and kaempferol 3-O-
rutinoside2) (10) [13], respectively, by comparison of their spectroscopic data with
those previously described in the literatures.
1
)
)
Arbitrary atom numbering; for systematic names, see Exper. Part.
For formulas, see corresponding references.
2
ꢀ 2010 Verlag Helvetica Chimica Acta AG, Zꢁrich

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Compound 1 was obtained as an optically active amorphous powder. The molecular
formula of 1, C22H32O11, was confirmed by HR-FAB-MS (m/z 495.1855 ([M þ Na]þ)).
1
The H-NMR spectrum of 1 (Table 1) showed signals due to one olefinic H-atom at
Table 1. 1H- and 13C-NMR Data (400 and 100 MHz, resp.; in CD3OD) of 1 and 21). d in ppm, J in Hz.
1
2
d(H)
d(C)
d(H)
d(C)
HꢀC(1)
HꢀC(3)
C(4)
5.56 (d, J ¼ 6.6)
97.7
153.7
111.5
31.5
5.53 (d, J ¼ 6.3)
97.6
153.2
112.1
31.3
7.47 (s)
7.46 (s)
–
–
HꢀC(5)
2.91 (br. dd, J ¼ 6.6, 6.0)
1.86 (br. ddd, J ¼ 13.7, 6.6, 6.0),
2.03 (br. ddd, J ¼ 13.7, 7.3, 6.0)
4.14 (br. dt, J ¼ 11.2, 6.6),
4.16 (ddd, J ¼ 11.2, 7.3, 6.0)
5.79 (ddd, J ¼ 17.3, 10.5, 8.5)
2.65 (ddd, J ¼ 8.5, 6.6, 6.0)
5.25 (dd, J ¼ 10.5, 1.0),
5.30 (dd, J ¼ 17.3, 1.0)
–
2.89 (br. dd, J ¼ 6.6, 5.9)
1.84 (overlapped),
2.08 (br. ddd, J ¼ 13.9, 7.1, 5.9)
4.14 (br. dt, J ¼ 11.0, 6.6),
4.19 (ddd, J ¼ 11.0, 7.1, 5.9)
5.79 (ddd, J ¼ 17.3, 10.5, 8.5)
2.65 (ddd, J ¼ 8.5, 6.3, 5.9)
5.25 (dd, J ¼ 10.5, 1.2),
5.29 (dd, J ¼ 17.3, 1.2)
–
CH2(6)
30.2
30.1
CH2(7)
64.2
64.3
HꢀC(8)
HꢀC(9)
CH2(10)
135.8
45.6
119.6
135.9
45.5
119.5
C(11)
169.2
51.8
100.2
74.7
78.5
71.6
78.1
62.8
171.2
–
MeOꢀC(11)
HꢀC(1’)
HꢀC(2’)
HꢀC(3’)
HꢀC(4’)
HꢀC(5’)
CH2(6’)
3.67 (s)
4.69 (d, J ¼ 7.8)
–
4.69 (d, J ¼ 7.8)
100.2
74.7
78.5
71.6
78.0
62.8
3.18 (dd, J ¼ 9.0, 7.8)
3.30 (overlapped)
3.30 (overlapped)
3.30 (overlapped)
3.66 (overlapped),
3.90 (dd, J ¼ 12.0, 2.0)
–
3.19 (dd, J ¼ 9.0, 7.8)
3.30 (overlapped)
3.30 (overlapped)
3.30 (overlapped)
3.66 (dd, J ¼ 12.0, 5.9),
3.90 (dd, J ¼ 12.0, 2.0)
–
C(1’’)
C(2’’)
HꢀC(3’’)
Me(4’’)
Me(5’’)
169.6
129.7
138.7
14.4
169.7
129.7
138.6
14.4
–
–
6.85 (br. dq, J ¼ 7.3, 1.2)
1.80 (br. d, J ¼ 7.3)
1.81 (br. s)
6.86 (br. dq, J ¼ 7.0, 1.2)
1.79 (br. dd, J ¼ 7.0, 1.2)
1.81 (br. q, J ¼ 1.2)
12.1
12.1

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Helvetica Chimica Acta – Vol. 93 (2010)
d(H) 7.47 (s, HꢀC(3)1)), vinyl H-atoms at d(H) 5.25 (dd, J ¼ 10.5, 1.0 Hz, HaꢀC(10)),
5.30 (dd, J ¼ 17.3, 1.0 Hz, HbꢀC(10)), and 5.79 (ddd, J ¼ 17.3, 10.5, 8.5 Hz, HꢀC(8)),
two acetal H-atoms at d(H) 4.69 (d, J ¼ 7.8 Hz, HꢀC(1’)) and 5.56 (d, J ¼ 6.6 Hz,
HꢀC(1)), one MeO group at d(H) 3.67 (s, MeOꢀC(11)), two CH2 groups at d(H) 1.86
(br. ddd, J ¼ 13.7, 6.6, 6.0 Hz, HaꢀC(6)), 2.03 (br. ddd, J ¼ 13.7, 7.3, 6.0 Hz, HbꢀC(6)),
4.14 (br. dt, J ¼ 11.2, 6.6 Hz, HaꢀC(7)), and 4.16 (ddd, J ¼ 11.2, 7.3, 6.0 Hz, HbꢀC(7)),
and two CH groups at d(H) 2.91 (br. dd, J ¼ 6.6, 6.0 Hz, HꢀC(5)) and 2.65 (ddd, J ¼
8.5, 6.6, 6.0 Hz, HꢀC(9)). The 1H,1H-COSY experiment of 1 in combination with the
HMQC spectrum revealed the partial structures shown by the bold lines in Fig. 1. Acid
hydrolysis of 1 yielded d-glucose which was identified by its retention time and optical
1
rotation by means of chiral detection in HPLC analysis. The H- and 13C-NMR data
(Table 1) were closely related to those of secologanol ¼ (2S,3R,4S)-3-ethenyl-2-(b-d-
glucopyranosyloxy)-3,4-dihydro-4-(2-hydroxyethyl)-2H-pyran-5-carboxylic acid meth-
yl ester [14], except for the presence of signals due to a tigloyl group (d(H) 6.85 (dq,
J ¼ 7.3, 1.2 Hz, HꢀC(3’’)), 1.81 (br. s, Me(5’’)), and 1.80 (br. d, J ¼ 7.3 Hz, Me(4’’));
d(C) 169.6 (C(1’’)), 138.7 (C(3’’)), 129.7 (C(2’’)), 14.4 (C(4’’)), and 12.1 (C(5’’)).
1
Furthermore, the H- and 13C-NMR chemical shifts of the CH2(7) moiety of 1 were
shifted downfield by þ 0.6 ppm (2 HꢀC(7)) and þ 2.9 ppm (C(7)) compared with
those of secologanol, suggesting that the additional tigloyl group in 1 is located at
OHꢀC(7) of secologanol. This finding was supported by the HMBC cross-peaks
1
between CH2(7) and C(1’’). Other HMBC and H,1H-COSY (Fig. 1), and NOESY
(HꢀC(1)/HꢀC(8), HꢀC(5)/HꢀC(9)) correlations of 1 confirmed the proposed
structure. The absolute configuration of the aglycone of 1 was not determined. From
the above data, the structure of 1 was established as rel-(2R,3S,4R)-3-ethenyl-2-(b-d-
glucopyranosyloxy)-3,4-dihydro-4-{2-[(2-methylbut-2-enoyl)oxy]ethyl}-2H-pyran-5-
carboxylic acid methyl ester, and named 7-O-tigloylsecologanol.
Fig. 1. 1H,1H-COSY Correlations (bold line) and key HMBCs
(full-line arrows) of 1
Compound 2 was obtained as an optically active amorphous powder. In the HR-
FAB-MS, the m/z at 481.1671 ([M þ Na]þ) indicated the molecular formula of 2 as
C21H30O11. Acid hydrolysis of 2 in the above described manner gave only d-glucose.
1
The H- and 13C-NMR spectra of 2 (Table 1) closely resembled those of 1, except for

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the absence of signals for a MeO group. A comparison of the 13C-NMR chemical shifts
of 1 and 2 indicated that the C(11)¼O group (d(C) 171.2) of 2 was deshielded by
2.0 ppm with respect to that of 1. The molecular formula of 2 represented a loss of a
CH2 unit compared to that of 1. These findings suggested that 2 is the de-O-methyl
1
analogue of 1. The complete assignments of the H- and 13C-NMR signals of 2 were
confirmed by the 1H,1H-COSY, HMQC, and HMBC experiments (Fig. 2). The
absolute configuration of the aglycone of 2 was not determined. From the above data,
the structure of 2 was established as rel-(2R,3S,4R)-3-ethenyl-2-(b-d-glucopyranosy-
loxy)-3,4-dihydro-4-{2-[(2-methylbut-2-enoyl)oxy]ethyl}-2H-pyran-5-carboxylic acid,
and named 7-O-tigloylsecologanolic acid.
Fig. 2. 1H,1H-COSY Correlations (bold line) and key HMBCs (full-
line arrows) of 2
Compound 3 was obtained as an optically active amorphous powder. The molecular
formula of 3, C31H40O16, was confirmed by HR-FAB-MS (m/z 691.2207 ([M þ Na]þ)).
The 1H-NMR spectrum of 3 (Table 2) showed the signals due to one 1,2,6-trisubstituted
aromatic ring at d(H) 6.60 (dd, J ¼ 8.5, 1.0 Hz, HꢀC(5)), 6.74 (dd, J ¼ 8.3, 1.0 Hz,
HꢀC(3)), and 7.28 (dd, J ¼ 8.5, 8.3 Hz, HꢀC(4)), one ortho-disubstituted aromatic
ring at d(H) 7.06 (dt, J ¼ 7.6, 1.0 Hz, HꢀC(5’’)), 7.21 (dd, J ¼ 8.3, 1.0 Hz, HꢀC(3’’)), 7.32
(ddd, J ¼ 8.3, 7.6, 1.5 Hz, HꢀC(4’’)), and 7.54 (dd, J ¼ 7.6, 1.5 Hz, HꢀC(6’’)), one CH2 as
an AB system at d(H) 5.48 (d, J ¼ 13.0 Hz, HaꢀC(7’’)) and 5.53 (d, J ¼ 13.0 Hz,
HbꢀC(7’’)), and two anomeric H-atoms at d(H) 4.94 (d, J ¼ 7.8 Hz, HꢀC(1’’’)) and 5.03
(d, J ¼ 7.8 Hz, HꢀC(1’)). Acid hydrolysis of 3 in the above described manner gave only
d-glucose. The coupling constants of the two anomeric H-atoms indicated that the
glycosyl linkages are of b-configuration. These spectral features were almost identical
to those of henryoside ¼ 2-{{[2-(b-d-glucopyranosyloxy)-6-hydroxybenzoyl]oxy}me-
thyl}phenyl b-d-glucopyranoside isolated from V. henryi [15]. This was also supported
by the HMBC correlations shown in Fig. 3.
1
The H- and 13C-NMR spectra of 3 (Table 2), however, showed the presence of
additional signals due to one C¼O group (d(C) 178.1 (C(1’’’’))), one primary Me group
(d(H) 0.98 (t, J ¼ 7.1 Hz, Me(4’’’’); d(C) 12.0 (C(4’’’’))), one secondary Me group (d(H)
1.19 (d, J ¼ 7.1 Hz, Me( 5’’’’); d(C) 17.0 (C(5’’’’))), one CH2 group (d(H) 1.54 (dquint.,
J ¼ 14.6, 7.1 Hz, HaꢀC(3’’’’)) and 1.74 (dquint., J ¼ 14.6, 7.1 Hz, HbꢀC(3’’’’)); d(C) 28.1

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Helvetica Chimica Acta – Vol. 93 (2010)
Table 2. 1H- and 13C-NMR Data (400 and 100 MHz, resp.; in CD3OD) of 31). d in ppm, J in Hz.
d(H)
d(C)
d(H)
d(C)
C(1)
C(2)
HꢀC(3)
HꢀC(4)
HꢀC(5)
C(6)
–
–
110.7
158.1
107.7
134.2
111.8
160.1
170.0
102.4
73.1
HꢀC(3’’)
HꢀC(4’’)
HꢀC(5’’)
HꢀC(6’’)
CH2(7’’)
HꢀC(1’’’)
HꢀC(2’’’)
HꢀC(3’’’)
HꢀC(4’’’)
HꢀC(5’’’)
CH2(6’’’)
7.21 (dd, J ¼ 8.3, 1.0)
7.32 (ddd, J ¼ 8.3, 7.6, 1.5)
7.06 (dt, J ¼ 7.6, 1.0)
7.54 (dd, J ¼ 7.6, 1.5)
5.48, 5.53 (d, J ¼ 13.0, each)
4.94 (d, J ¼ 7.8)
116.6
130.8
123.6
130.7
63.7
102.9
74.9
78.3
6.74 (dd, J ¼ 8.3, 1.0)
7.28 (dd, J ¼ 8.5, 8.3)
6.60 (dd, J ¼ 8.5, 1.0)
–
C(7)
–
3.16 – 3.54 (overlapped)
3.16 – 3.54 (overlapped)
3.16 – 3.54 (overlapped)
3.16 – 3.54 (overlapped)
3.70 (dd, J ¼ 12.2, 4.8),
3.88 (dd, J ¼ 12.2, 1.7)
–
HꢀC(1’)
HꢀC(2’)
HꢀC(3’)
HꢀC(4’)
5.03 (d, J ¼ 7.8)
3.16 – 3.54 (overlapped)
4.99 (t, J ¼ 9.3)
3.16 – 3.54 (overlapped)
71.3
78.0
62.2
78.2
69.4
HꢀC(5’)
CH2(6’)
3.16 – 3.54 (overlapped)
3.67 (dd, J ¼ 12.0, 4.6),
3.83 (dd, J ¼ 12.0, 1.2)
–
78.1
62.5
C(1’’’’)
HꢀC(2’’’’)
178.1
42.6
2.48 (sext., J ¼ 7.1)
C(1’’)
C(2’’)
126.7
156.9
CH2(3’’’’)
1.54 (dquint., J ¼ 14.6, 7.1),
1.74 (dquint., J ¼ 14.6, 7.1)
0.98 (t, J ¼ 7.1)
28.1
–
Me(4’’’’)
Me(5’’’’)
12.0
17.0
1.19 (d, J ¼ 7.1)
Fig. 3. 1H,1H-COSY correlations (bold line) and key
HMBCs (full-line arrows) of 3
(C(3’’’’))), and one CH group (d(H) 2.48 (sext., J ¼ 7.1 Hz, HꢀC(2’’’’)); d(C) 42.6
1
(C(2’’’’))). Detailed analysis of the H- and 13C-NMR spectra of the additional signals
were undertaken with the aid of 1H,1H-COSY, HMQC, and HMBC experiments
(Fig. 3), suggesting the additional moiety to be a 2-methylbutanoyl moiety. From the
findings presented above, compound 3 was deduced to be a 2-methylbutanoic acid ester
of henryoside. The additional 2-methylbutanoyl moiety of 3 is attached to OHꢀC(3’)
of henryoside as established by the HMBC between HꢀC(3’) (d(H) 4.99) and C(1’’’’).
Other HMBCs (Fig. 3) confirmed the planar structure of 3. To determined the absolute
configuration at C(2’’’’) of the 2-methylbutanoyl moiety of 3, we referred to a reported
HPLC method by means of a chiral column [16]. Briefly, alkaline hydrolysis of 3 was
carried out to afford 2-methylbutanoic acid (11), which was converted into the

Helvetica Chimica Acta – Vol. 93 (2010)
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corresponding acyl chloride 12 with SOCl2. Treatment of 12 with aniline
(¼ benzenamine) afforded amide 13 (Scheme). The (2S)-2-methyl-N-phenylbutana-
mide and racemic (2RS)-2-methyl-N-phenylbutanamide were synthesized from
commercial (2S)-2-methylbutanoic acid and (2RS)-2-methylbutanoic acid as described
for 13 above. The (2RS)-methyl-N-phenylbutanamide was separated into its enan-
tiomers by HPLC with a chiral column. Comparison of the retention time of 13 with the
synthetic (2S)-2-methyl-N-phenylbutanamide and racemic (2RS)-2-methyl-N-phenyl-
butanamide revealed the absolute configuration at C(2’’’’) of the 2-methylbutanoyl
moiety of 3 to be (S). From the above data, the structure of 3 was established as 2’’-(b-
d-glucopyranosyloxy)benzyl 2-hydroxy-6-{{3-O-[(2S)-2-methylbutanoyl]-b-d-gluco-
pyranosyl}oxy}benzoate, and named 3’-O-[(2S)-2-methylbutanoyl]henryoside.
Scheme. Synthesis of (2S)-2-Methyl-N-phenylbutanamide (13) from 3
We thank Mrs. S. Sato and T. Matsuki of Tohoku Pharmaceutical University for NMR and MS
measurements.
Experimental Part
General. Column chromatography (CC): silica gel (SiO2; 70 – 230 mesh; Merck) and Sephadex LH-
20 (Pharmacia Fine Chemicals). HPLC: Tosoh-8020 apparatus; TSKgel-ODS-80TM column (5 mm,
6.0 mm i.d. ꢁ 15 cm; Tosoh), TSKgel-ODS-120T column (10 mm, 7.8 mm i.d. ꢁ 30 cm; Tosoh), and
Cosmosil-5SL column (5 mm, 10 mm i.d. ꢁ 25 cm; Nacalai tesque); tR in min. Optical rotation: Jasco-DIP-
360 digital polarimeter. UV Spectra: Beckman-DU-64 spectrometer; lmax (log e) in nm. NMR Spectra:
Jeol-JNM-GSX-400 spectrometer; d in ppm rel. to Me4Si; J in Hz. EI-, HR-EI-, FAB-, and HR-FAB-MS:
Jeol-JMS-303 mass spectrometer; in m/z (rel. %), with glycerol as matrix for FAB.
Plant Material. Leaves of Viburnum plicatum Thunb. var. tomentosum Miq. were collected in June
2007 in Sendai, Miyagi prefecture, Japan, and identified by M. K. A voucher specimen is deposited in the
laboratory of M. K. (No. 2007-6-KM2).
Extraction and Isolation. Fresh leaves of V. plicatum Thunb. var. tomentosum Miq. (450 g) were
extracted two times consecutively (10 d each time) with MeOH (2 ꢁ 8 l) at r.t. The MeOH extract was
concentrated and the residue (41.7 g) suspended in H2O (500 ml). This suspension was successively
extracted with CHCl3 (3 ꢁ 500 ml), AcOEt (3 ꢁ 500 ml), and BuOH (3 ꢁ 500 ml). The AcOEt-soluble
fraction (3.1 g) was subjected to CC (Sephadex LH-20, 50% MeOH), and the eluate was separated into
Fractions 1 – 13. Fr. 3 was subjected to prep. HPLC (TSKgel-ODS-80TM, MeOH/H2O 1:2, flow rate
1.0 ml/min, column temp. 408, detection at 205 nm) to give five Peaks 1 – 5. Peak 3 (tR 48) was purified by
prep. HPLC (Cosmosil-5SL, CH2Cl2/MeOH/H2O 80 :10 :1, flow rate 1.5 ml/min, r.t., detection at
225 nm): 2 (10.5 mg; tR 35.4). Peak 4 (tR 65) was purified by prep. HPLC (Cosmosil-5SL, CH2Cl2/MeOH/
H2O 70 :10 :1, flow rate 1.5 ml/min, r.t., detection at 225 nm): 3 (25.0 mg; tR 31.2). Peak 5 (tR 100) was
purified by prep. HPLC (Cosmosil-5SL, CH2Cl2/MeOH/H2O 80 :10 :1, flow rate 1.5 ml/min, r.t.,
detection at 225 nm): 1 (8.5 mg; tR 31.2) and 4 (30.5 mg; tR 34.0). The BuOH-soluble fraction (9.7 g) was
subjected to CC (SiO2, CHCl3/MeOH/H2O 30 :10 :1), and the eluate was separated into Frs. 1 – 3. Fr. 1
was further subjected to CC (Sephadex LH-20, 50% MeOH), and the eluate was separated into Frs. 1.1 –
1.5. Fr. 1.2 was subjected to prep. HPLC (TSKgel-ODS-80TM, MeOH/H2O 1:3, flow rate 0.8 ml/min,

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Helvetica Chimica Acta – Vol. 93 (2010)
column temp. 408, detection at 205 nm): 5 (3.0 mg; tR 38.7) and 6 (6.5 mg; tR 41.0). Fr. 1.4 was subjected to
prep. HPLC (TSKgel-ODS-120T, MeOH/H2O 2 :5, flow rate 1.5 ml/min, column temp. 408, detection at
205 nm): 7 (4.8 mg; tR 28.0), 8 (6.5 mg; tR 31.0), 9 (7.0 mg; tR 42.0), and 10 (12.5 mg; tR 48.6).
7-O-Tigloylsecologanol ( ¼ rel-(2R,3S,4R)-3-Ethenyl-2-(b-d-glucopyranosyloxy)-3,4-dihydro-4-{2-
[(2-methyl-1-oxobut-2-en-1-yl)oxy]ethyl}-2H-pyran-5-carboxylic Acid Methyl Ester; 1): Amorphous
powder. [a]2D7 ¼ ꢀ70.0 (c ¼ 0.20, MeOH). UV (MeOH): 221 (4.07). 1H- and 13C-NMR (CD3OD):
Table 1. FAB-MS: 495 ([M þ Na]þ). HR-FAB-MS: 495.1855 ([M þ Na]þ, C22H32NaO1þ1 ; calc. 495.1829).
7-O-Tigloylsecologanolic Acid ( ¼ rel-(2R,3S,4R)-3-Ethenyl-2-(b-d-glucopyranosyloxy)-3,4-dihy-
dro-4-{2-[(2-methyl-1-oxobut-2-en-1-yl)oxy]ethyl}-2H-pyran-5-carboxylic Acid; 2): Amorphous powder.
[a]2D7 ¼ ꢀ116.2 (c ¼ 0.37, MeOH). UV (MeOH): 219 (4.18). 1H- and 13C-NMR (CD3OD): Table 1. FAB-
MS: 481 ([M þ Na]þ). HR-FAB-MS: 481.1671 ([M þ Na]þ, C21H30NaO1þ1 ; calc. 481.1686).
3’-O-[(2S)-2-Methylbutanoyl]henryoside ( ¼ 2’’-(b-d-Glucopyranosyloxy)benzyl 2-Hydroxy-6-{{3-
O-[(2S)-2-methylbutanoyl]-b-d-glucopyranosyl}oxy}benzoate ¼ 2-{{{2-[(b-d-Glucopyranosyl)oxy]phe-
nyl}methoxy}carbonyl}-3-hydroxyphenyl b-d-Glucopyranoside 3-[(2S)-2-Methylbutanoate; 3): Amor-
phous powder. [a]2D7 ¼ ꢀ43.5 (c ¼ 0.23, MeOH). UV (MeOH): 306 (3.24), 273 (3.39), 246 (3.67), 205
(4.38). 1H- and 13C-NMR (CD3OD): Table 2. FAB-MS: 691 ([M þ Na]þ). HR-FAB-MS: 691.2207
([M þ Na]þ, C31H40NaO1þ6 ; calc. 691.2214).
Alkaline Hydrolysis and Determination of the Absolute Configuration of the 2-Methylbutanoyl
Moiety in 3. Compound 3 (5.0 mg) was treated with 5% KOH soln. (1.5 ml) for 1.5 h at 408. The soln. was
neutralized with 1m HCl and partitioned with CHCl3. The CHCl3 layer was dried (Na2SO4) and
concentrated. The residue containing 2-methylbutanoic acid (11) was refluxed for 1 h with SOCl2
(600 ml). The excess SOCl2 was removed under reduced pressure to afford 2-methylbutanoyl chloride
(12). Chloride 12 was dissolved in CHCl3 (5 ml), and aniline (500 ml) was added dropwise. After stirring
for 1.5 h at r.t., the CHCl3 layer was washed three times with 4m HCl, dried (Na2SO4), and concentrated:
amide 13.
(2S)-2-Methyl-N-phenylbutanamide and racemic (2RS)-2-methyl-N-phenylbutanamide were syn-
thesized from commercial (2S)-2-methylbutanoic acid and (2RS)-2-methylbutanoic acid by the method
described above. The (2R)- and (2S)-enantiomers of 2-methyl-N-phenylbutanamide were separated by
HPLC (Daicel Chiral OD (10 mm, 4.6 mm i.d. ꢁ 25 cm; Daicel Chemical Co.), column temp. r.t., hexane/
i-PrOH 10 :1, flow rate 0.5 ml/min, detection at 254 nm): 13, tR 24.0; (2S)-2-methyl-N-phenylbutanamide,
tR 24.0; (2R)-2-methyl-N-phenylbutanamide, tR 26.4.
1
(2S)-2-Methyl-N-phenylbutanamide: Colorless crystals. [a]2D7 ¼ þ26.7 (c ¼ 1.80, CHCl3). H-NMR
(400 MHz, CDCl3): 7.54 (br. d, J ¼ 7.8); 7.32 (t, J ¼ 7.8); 7.10 (br. t, J ¼ 7.8); 2.25 (sext., J ¼ 7.3); 1.78
(dquint., J ¼ 15.1, 7.3); 1.51 (dquint., J ¼ 15.1, 7.3); 1.24 (d, J ¼ 7.3); 0.97 (t, J ¼ 7.3). EI-MS: 177 (Mþ). HR-
EI-MS: 177.1154 (Mþ, C11H15NOþ; calc. 177.1154).
Determination of the Absolute Configuration of the Sugar Residues in Compounds 1 – 3. Each
compound (ca. 1 mg) was refluxed with 1m HCl (1 ml) for 5 h. The mixture was neutralized with Ag2CO3
and filtered. The soln. was concentrated and dried to give a sugar fraction. The sugar fraction was
analyzed by HPLC TSKgel Amide-80 (10 mm, 7.8 mm i.d. ꢁ 30 cm; Tosoh), column temp. 458, MeCN/
H2O 4 :1, flow rate 1.0 ml/min, chiral detection (Jasco OR-2090). Identification of the d-glucose present
in the sugar fraction was established by comparison of the tR and [a]D with that of an authentic sample; tR
39.0 (d-glucose, pos. [a]D).
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Received June 15, 2009