Studies on the relative reactivity of three hydroxyl groups in aconitine

Article abstract of DOI:10.1080/10286020.2012.684684

The relative reactivity of three hydroxyl groups in aconitine toward acetylation, chlorination, sulfonylation, and oxidation has been studied in this paper. The reduction of C-3 ketone and C-15 ketone derivatives of aconitine was also investigated. It was found that (1) the relative reactivity of three hydroxyl groups toward acetylation, chlorination, and sulfonylation is 3-OH>13-OH>>15-OH; (2) 3-OH is much more reactive than 15-OH toward oxidation; and (3) reduction of the carbonyl group at C-3 with NaBH₄ generated a pair of C-3 epimers, while the reduction products of the carbonyl group at C-15 depend largely on the specific reducing agent and the absolute configuration of 16-OCH₃. When the substrate has 16-OCH₃, its carbonyl group at C-15 can be reduced with NaBH₄ to yield exclusively the 15-OH-containing product. Upon replacement of reducing agent NaBH₄ with LiAlH₄, the C-15 carbonyl group can be reduced to yield a pair of C-15 epimers. On the other hand, when the substrate has 16-OCH₃, C-15 carbonyl group can only be reduced to generate 15-OH-containing product.

Full text of DOI:10.1080/10286020.2012.684684

Journal of Asian Natural Products Research
Vol. 14, No. 7, July 2012, 665–677
Studies on the relative reactivity of three hydroxyl groups in aconitine
Xue-Ke She, Xi-Xian Jian, Dong-Lin Chen, Qiao-Hong Chen and Feng-Peng Wang*
Department of Chemistry of Medicinal Natural Products, West China College of Pharmacy,
Sichuan University, Chengdu 610041, China
(Received 14 February 2012; final version received 10 April 2012)
The relative reactivity of three hydroxyl groups in aconitine toward acetylation,
chlorination, sulfonylation, and oxidation has been studied in this paper. The reduction
of C-3 ketone and C-15 ketone derivatives of aconitine was also investigated. It was
found that (1) the relative reactivity of three hydroxyl groups toward acetylation,
chlorination, and sulfonylation is 3-OH . 13-OH . .15-OH; (2) 3-OH is much
more reactive than 15-OH toward oxidation; and (3) reduction of the carbonyl group at
C-3 with NaBH4 generated a pair of C-3 epimers, while the reduction products of
the carbonyl group at C-15 depend largely on the specific reducing agent and the
absolute configuration of 16-OCH3. When the substrate has 16b-OCH3, its carbonyl
group at C-15 can be reduced with NaBH4 to yield exclusively the 15a-OH-containing
product. Upon replacement of reducing agent NaBH4 with LiAlH4, the C-15 carbonyl
group can be reduced to yield a pair of C-15 epimers. On the other hand, when the
substrate has 16a-OCH3, C-15 carbonyl group can only be reduced to generate 15a-
OH-containing product.
Keywords: aconitine; regioselective reaction; oxidation; chlorination; sulfonation
1. Introduction
aconitine, including N-deethylation [4,5],
N-oxidation [6], amidation [5–8] and
formation of nitrones [9], pyrolysis
[10,11], deoxydation [12], methanolysis
[13], O-demethylation [14–16], selective
hydrolysis [17], and introduction of sugar
[18], have been reported. As part of our
ongoing research project, we attempt to
semi-synthesize the analogs of diterpenoid
alkaloids for structure–activity relation-
ship study. In this paper, we wish to report
the regioselective reactions, including
acetylation, chlorination, sulfonation, and
oxidation of three hydroxyl groups in
aconitine.
Aconitine represents the first example of
diterpenoid alkaloid, which was isolated
by Geiger from Aconitum napellus L. in
1833 [1]. Its structural complexity and
physiological properties, especially its
toxicity toward heart and nerve system,
have stimulated scientists’ strong attention
to its sources, chemical reactions, and
medicinal chemistry [2]. Aconitine is not
only the key toxic component in the famous
traditional Chinese medicine including
Chuan Wu, Fu Zi, and Cao Wu, but is also
applied to many pharmacological investi-
gations as a tool drug [2]. Its derivative, 3-
acetylaconitine, has been approved for
clinical treatment of various pains in
China [3]. In addition to the biological
activities, some chemical reactions of
2. Results and discussion
It has been reported by Pelletier’s research
group [16] that treatment of aconitine (1)
*Corresponding author. Email: wfp@scu.edu.cn
ISSN 1028-6020 print/ISSN 1477-2213 online
q 2012 Taylor & Francis
http://dx.doi.org/10.1080/10286020.2012.684684
http://www.tandfonline.com

666
X.-K. She et al.
with acetic anhydride in pyridine or acetic
chloride at room temperature could gen-
erate various acetylated products (2–4)
(Figure 1). This paper has mentioned that 3-
OH is most reactive toward acetylation, but
no detailed description on the relative
reactivity of three hydroxyl groups toward
acetylation has been reported. It was
observed by us that acetylated products of
aconitine depended strongly upon the
amount of catalyst (such as TsOH) and
reaction time. Reaction of aconitine (1)
with acetic anhydride in the presence of
1.1 equivalent of TsOH at room tempera-
ture yielded 3-acetylaconitine (2, 43%),
together with 48% starting material. 3,13-
Diacetylaconitine (3) was exclusively
obtained in 92% yield when the reaction
time was prolonged to 12 h, while 3,13,
15-triacetylaconitine (4) was obtained in
97% yield only when the amount of
TsOH was increased to 2 equivalents and
the reaction time was prolonged to 48 h.
The 1H and 13C NMR spectral data of
compounds 2–4 are consistent with those
reported in the literature [16,19,20]. The
above-mentioned results indicated that
the relative reactivity of three hydroxyl
groups in aconitine toward acetylation is
3-OH . 13-OH . .15-OH.
Treatment of aconitine (1) with SOCl2
at room temperature for 12 h generated
exclusively compound 5 in 89% yield. The
1H and 13C NMR spectra of 5 showed the
presence of a two-substituted double bond
(dH 6.06, dd, J ¼ 10.0 and 3.2 Hz, H-2; dH
5.79, d, J ¼ 12.5 Hz, H-3; dC 125.5, 137.7
d). Its structure was identified based on the
OH
OH
OR2
OCH3
OCH3
OCH3
OBz
OCH3
OCH3
OCH3
OBz
OH
OBz
OR3
N
H
N
H
N
H
OH
R1
OAc
OAc
OAc
O
OCH3
OCH3
OCH3
H3CO
H3CO
H3CO
8
5
1
R1=αOH
R2=R3=H
OH
OH
2
3
4
6
7
R1=αOAc R2=R3=H
OCH3
OBz
OH
R2
R1=αOAc R2=Ac R3=H
R1=αOAc R2=R3=Ac
R1=αOMs R2=R3=H
R1=αOTs R2=R3=H
OCH3
OBz
O
N
H
N
OAc
R3
O
R1
H
11 R1=βOH R2=R3=H
12 R1=βOAc R2=R3=H
OCH3
OCH3
H3CO
H3CO
9
10 R1=OAc R2=βOCH3 R3=OAc
13 R1=OH R2=βOCH3 R3=H
14 R1=OH R2=αOCH3 R3=H
OR1
OH
OH
OCH3
OCH3
OCH3
OR
OCH3
OCH3
OCH3
OR1
R2
OR
N
H
N
N
H
OH
OH
R1O
H
H
HO
H
HO
H
OCH3
OCH3
OCH3
H3CO
H3CO
H3CO
17 R1=H R2=OH
18 R1=Ac R2=OAc
19 R=Bz
20 R=H
15 R=Bz
16 R=H
Figure 1. Structures of compounds 1–20.

Journal of Asian Natural Products Research
667
comparison of its NMR data with those in
the literature [21,22]. Obviously, com-
pound 5 was produced through a chlori-
nation–elimination process, suggesting
that the 3-hydroxyl group in aconitine is
easier to be replaced by chlorine than the
other two hydroxyl groups.
presence of a ketone carbonyl group at dC
205.0 (s), which can be readily assigned at
C-15 by its 1H (13C) NMR and HR-ESI-MS.
This also supported that the hydroxyl group
at C-3 is more reactive than that at C-15
toward oxidation.
Reduction of compound 8 with NaBH4
at room temperature for 1 h yielded
aconitine (1) as a major product along
with a minor one. The minor product was
Similarly, treatment of aconitine (1)
with MsCl or TsCl catalyzed by 4-
dimethylaminopyridine (DMAP) at room
temperature for 1 h or 20 h yielded
exclusively 6 (81%) or 7 (85%). The H-3
signal in the 1H NMR spectra of 6 and 7 is
downshifted to dH ,4.70, indicating that
the hydroxyl group at C-3 is esterified. This
suggested that only the hydroxyl group at
C-3 of aconitine was sulfonated under this
reaction condition. The hydroxyl group at
C-15 cannot be sulfonated even at elevated
reaction temperature and prolonged reac-
tion time. Compounds 6 and 7 were fully
1
established as 11 by analyzing its H and
13C NMR data (Table 1) and HR-ESI-MS.
To determine the relative configuration of
3-OH in 11, its 3-acetyl derivative 12 was
prepared by reaction of 11 with acetic
anhydride in pyridine. Comparison of the
1H NMR spectrum of 12 with that of 11
indicated the presence of an additional
acetyl group (d 2.05, s). In the NOE
difference spectrum (NOEds) experiment,
the correlation between H-3 (d 5.37, brs,
W1/2 ¼ 4.8 Hz) and H-19 (d 2.59,ABq,
J ¼ 11.8 Hz) indicated the b-orientation of
3-OH in compound 11.
characterized on the basis of its 1H and 13
NMR data (Table 1) and HR-ESI-MS.
C
Treatment of aconitine (1) with 1
equivalent of Jones reagent at room
temperature for 30min yielded ketones 8
(61%) and 9 (19%). The 13C NMR spectrum
of 8 (Table 1) showed a ketone signal at dC
214.6, and its 1H NMR spectrum lacks the
signal of H-3 when compared with that of
aconitine. This supported that the hydroxyl
group at C-3 in aconitine was oxidized to
ketone. The NMR spectra of compound 9
exhibited the signals at dH 6.27 (1H, d,
J ¼ 10.4 Hz) and at dH 6.46 (1H, d,
J ¼ 10.0Hz) for an a,b-unsaturated ketone.
Comparison of the NMR data of 9 with
those of aconitine indicated the absence
of resonances corresponding to a methoxyl
group. The structure of 9 was confirmed by
We next attempt to investigate the
effect of configuration of 16-OCH3 on the
reductive products of the 15-carbonyl-
containing compound. Consequently, com-
pounds 13 and 14, each of them has a
ketone carbonyl group at C-15, were
prepared by pyrolysis of aconitine (1)
based on the procedure reported in the
literature [11]. The NMR data of com-
pounds 13 and 14 were consistent with
those reported in the literature [11]. No 2D
NMR data of these two compounds
has been reported in the literature [11], so
we confirmed the structure of 14, except for
comparison with those in the literature [11],
by analyzing its 2D NMR data. All 1H and
13C signals of compound 14 were assigned
based on its 2D NMR data (Table 2). This
also confirmed the structure of 13. In the
NOEds of 14, the key correlation between
H-16 (d 3.86, s) and H-20, 60 (d 7.98, d,
J ¼ 7.6 Hz) suggested the a-orientation of
16-OCH3 in compound 14.
1
its H and 13C NMR data (Section 3 and
Table 1, respectively). The formation of 8 or
9 suggested that the hydroxyl group at C-3 is
more reactive than that at C-15 toward
oxidation with Jones reagent. The hydroxyl
group at C-15 in compound 2 can only be
oxidized with 5 equivalents of Jones reagent
for 12h to form ketone 10 (83%). The 13
NMR spectrum (Table 1) of 10 showed the
C
Refluxing of compound 13 with
NaBH4 in THF for 14 h generated

668
X.-K. She et al.

Journal of Asian Natural Products Research
669

670
X.-K. She et al.
Table 2. NMR spectral data of compounds 13 and 14 (400 MHz for 1H, 100 MHz for 13C, CDCl3).
13
14
C [11]
Position
dC
dC [11]
dH mult (J in Hz)
dC
d
HMBC
1
2
3
4
5
6
7
8
83.4
34.0
71.4
43.0
48.0
83.9
42.3
48.4
38.5
43.4
50.8
35.9
76.4
79.4
211.8
89.0
61.7
76.1
83.5
34.1
71.6
43.5
48.1
84.0
42.5
48.5
38.6
43.1
50.9
36.1
76.6
79.5
211.8
89.2
61.7
76.2
3.07 hidden
2.07 m, 2.34 m
3.71 hidden
–
2.08 hidden
3.91 d (6.8)
2.74 hidden
2.46 hidden
2.92 m
2.21 m
–
1.81 m, 2.96 m
–
83.5
33.9
71.6
43.5
48.3
83.9
41.6
48.9
38.5
44.6
51.0
32.9
77.3
78.4
211.8
86.0
61.5
76.6
83.4
32.5
71.6
43.6
48.0
84.0
41.9
49.0
38.5
44.6
51.2
33.8
77.4
78.5
C-11, C-10, 1-OCH3
C-11, C-4
C-5, C-18
–
C-7, C-18, C-19
C-4, C-8, 6-OCH3
C-5, C-9, C-15
C-17
C-12, C-15
C-1, C-17
9
10
11
12
13
14
15
16
17
18
–
C-11, C-14, C-16
–
C-8, C-16
5.43 d (4.8)
–
3.86 s
211.7
86.0
61.6
76.6
–
C-8, C-12, 16-OCH3
C-5, C-6, C-10
C-3, C-5, 18-OCH3
2.96 brs
3.70, 3.62
ABq (9.2, 9.2)
2.40 d (11.6)
2.92 hidden
2.64 hidden
2.73 hidden
1.07 t (6.8)
3.20 q
3.24 q
3.84 q
3.34 q
–
19
21
47.2
49.1
47.4
49.1
47.2
49.2
47.6
49.4
C-3, C-5, C-17
C-17, C-19
22
13.3
56.1
57.9
61.8
13.3
56.1
57.9
61.9
13.3
56.0
57.7
62.2
13.2
56.0
57.9
62.3
C-21
C-1
C-6
C-16
C-18
–
1-OCH3
6-OCH3
16-OCH3
18-OCH3
COO
10
59.1
59.2
59.1
59.2
167.1
129.5
129.8
128.4
133.2
167.1
133.2
129.8
129.6
128.4
165.9
133.6
129.7
129.2
128.6
166.0
133.6
129.6
129.3
128.6
–
–
20, 60
7.98 d (7.6)
7.47 t (7.6)
7.61 t (7.6)
COO, C-40
C-10
30, 50
40
C-20, C-60
compounds 15 (18%) and 16 (30%). The
1H NMR spectrum of 15 is characteristic
of a signal at d 4.45 (dd, J ¼ 10.4 and
6.4 Hz) for H-15, indicating that the
carbonyl group at C-15 in compound 13
was reduced. The key correlation between
H-15 and H-20, 60 (d 8.04, d, J ¼ 7.2 Hz) in
its NOEds indicated that the hydroxyl
group at C-15 in 15 is a-oriented.
assigned to H-14b (Figure 2) [2]. In
conjunction with its HR-ESI-MS data, it is
readily determined that compound 16 was
the hydrolyzed product of 15. Finally, all
1
of the H and 13C NMR data of 16 were
assigned based on its 2D NMR data
(Table 3).
However, reaction of compound 13
with LiAlH4 yielded compound 17 (36%)
in addition to compound 16 (46%). These
two compounds exhibited identical mol-
ecular formulae (C25H41NO8) and identi-
cal substitution pattern (OCH3 £ 4,
OH £ 4) in their 1H and 13C NMR spectra
1
Comparison of the H NMR spectrum of
16 with that of 15 indicated that the signal
at d 4.49 (dd, J ¼ 10.4 and 6.4 Hz) can be
located to H-15b in compound 16 and the
resonance at d 3.79 (J ¼ 4.8 Hz) can be

Journal of Asian Natural Products Research
671
OH
OH
OCH3
OCH3
OH
OCH3
N
OCH3
N
OH
OH
OH
H
H
HO
H3CO
HO
OCH3
16
OCH3
20
H3CO
1H-1HCOSY
HMBC (H C)
1
Figure 2. Key H–1H COSY and HMBC correlations of compounds 16 and 20.
(Tables 1 and 3). Therefore, compound 17
is very likely the C-15 epimer of
compound 16. However, the b-orientation
of the hydroxyl group at C-15 in 17 cannot
be directly assigned by the chemical shift
1
and coupling constant of H-15. In the H
NMR spectrum of compound 18, the
global acetyl derivative of 17, the one
1
Table 3. 1H and 13C NMR spectral data of compounds 16 and 20 (400 MHz for H, 100 MHz
for 13C).
16a
dH mult (J ¼ Hz)
20b
dH mult (J ¼ Hz)
Position
dC
dC
1
2
3
4
5
6
7
8
3.10 hidden
1.92 m, 2.38 m
3.83 dd (6.8, 4.8)
–
2.06 d (6.8)
3.99 d (6.4)
2.52 hidden
2.72 hidden
2.41 m
1.91m
–
2.06 m, 2.52 m
–
3.79 d (4.8)
4.49 dd (10.4, 6.4)
3.30 hidden
3.06 s
3.68, 3.57
ABq (8.4, 8.8)
2.54 m
2.74 m
2.58 hidden
3.02 m
83.1 d
32.7 t
71.3 d
43.0 s
46.1 d
84.9 d
39.6 d
40.6 d
39.5 d
41.5 d
50.4 s
37.0 t
76.4 s
78.5 d
71.4 d
93.9 d
62.1 d
77.2 t
3.28 hidden
2.60 m
4.83 m
83.0 d
31.4 t
69.4 d
43.9 s
44.2 d
85.5 d
40.5 d
43.9 d
40.5 d
43.0 d
51.3 s
40.5 t
80.5 s
78.9 d
65.2 d
87.4 d
62.5 d
75.8 t
–
2.36 d (6.0)
4.14 d (6.4)
2.90 hidden
3.10 hidden
2.60 m
2.00 hidden
–
2.65 m, 2.90 m
–
4.49 d (4.8)
5.47 t (9.2)
4.42 d (8.4)
–
3.82, 3.86
ABq (9.6)
3.06 hidden
2.90 hidden
2.90 hidden
3.10 m
9
10
11
12
13
14
15
16
17
18
19
21
49.0 t
48.0 t
49.6 t
49.6 t
22
1.16 t (7.2)
3.26 s
3.30 s
12.9 q
55.8 q
57.9 q
61.9 q
1.28 t (6.8)
3.27 s
3.25 s
11.8 q
55.3 q
58.1 q
61.0 q
1-OCH3
6-OCH3
16-OCH3
3.64 s
3.72 s
a CDCl3; b C5D5N.

672
X.-K. She et al.
proton doublet signal at dH 5.32 (d,
J ¼ 4.8 Hz) can readily be assigned to H-
14 [2]. The resonances at dH 4.86 (dd,
J ¼ 12.0 and 6.0 Hz) and dH 5.15 (dd,
J ¼ 8.4 and 4.4 Hz) were assigned to H-3b
and H-15a based on the key correlations
with C-3 (dC 71.8 d) and C-15 (dC 69.8 d),
respectively, in its HMQC spectrum. The
correlation between OAc-15 and OCH3-
16b in its NOEds and coupling constant
(dd, J ¼ 8.4, and 4.4 Hz) of H-15 led to
confirm the b-orientation of 15-OAc of 18.
Similarly, reaction of compound 14
with NaBH4–THF under reflux for 4 h
yielded compounds 19 (11%) and 20
(43%). The 1H NMR spectrum of 19
exhibited four methoxy groups (d 3.28,
3.29, 3.30, 3.62) and a benzoyl (OBz)
group (dH 7.47, t, J ¼ 7.6 Hz; dH 7.61, t,
J ¼ 7.6 Hz; dH 8.01, d, J ¼ 7.2 Hz). Its
molecular formula was determined as
C32H45NO9 based on its HR-ESI-MS and
13C NMR experiments. In the NOEds of
19, selective irradiation of H-15 (d 4.62,t,
J ¼ 9.2 Hz) resulted in the signal enhance-
ment of H-20, 60 (d 8.01, d, J ¼ 7.2 Hz),
indicating the a-orientation of 15-OH in
compound 19. Comparison of the NMR
and HR-ESI-MS data of 20 with those of
19 suggested that compound 20 is the
hydrolyzed product of 19. The hydroxyl
group at C-15 was established as a-
oriented based on the coupling constant
aconitine was observed. The reduction
products of 3-ketone derivative (8) with
NaBH4 are a pair of C-3 epimers, while the
reduction products of 15-ketone derivatives
(13 and 14) depend greatly on the reducing
agents and the configuration of 16-OCH3.
When the substrate has 16b-OCH3, its
carbonyl group at C-15 can be reduced with
NaBH4 to yield exclusively the 15a-OH-
containing product. Replacement of redu-
cing agent NaBH4 with LiAlH4, the C-15
carbonyl group can be reduced to give a
pair of C-15 epimers. On the other hand,
when the substrate has 16a-OCH3, C-15
carbonyl group can only be reduced to
generate the 15a-OH-containing product.
3. Experimental
3.1 General experimental procedures
Optical rotations were measured in a
1.0 dm cell with a Perkin-Elmer 341
polarimeter (Perkin-Elmer, Waltham,
MA, USA); HRMS were obtained with a
BrukerBioTOFQ mass spectrometer
(Bruker Daltonics, Karlsruhe, Germany);
1H and 13C NMR spectra were acquired on
a Bruker AC-E 200 or a Varian INOVA-
400/54 spectrometer (Varian, Palo Alto,
CA, USA), with TMS as internal standard;
silica gel GF254 and silica gel H (10–
40 mm, Qingdao Chemical Factory,
Qingdao, China) were used for thin layer
chromatography (TLC) and column chro-
matography (CC). Zones on TLC (silica gel
G) plates were detected with the modified
Dragendorff’s reagent. Aconitine was
provided by our research group.
1
(J ¼ 9.2 Hz) of H-15 (d 5.47, t) in the H
NMR spectrum of 20.
It is worth noting that the reduction of
compound 14 with LiAlH4 or diisobutyl-
aluminum hydride (DIBAL-H) still gener-
ated 15a-OH-containing compound 20.
In conclusion, the hydroxyl group at C-
3 in aconitine (1) is more reactive than
that at C-13 or C-15 toward acetylation,
sulfonylation, chlorination, and oxidation.
The relative reactivity of three hydroxyl
groups in aconitine toward acetylation and
oxidation is 3-OH . 13-OH . .15-OH
and 3-OH . 15-OH, respectively. In this
study, neither 13- or/and 15-chlorinated
aconitine nor 13- or/and 15-sulfonated
3.2 Synthesis of derivatives of aconitine
3.2.1 Compound 2
Compound 2 (white amorphous powder,
460 mg, 43%) from aconitine (1, 1000 mg,
1.55 mmol) was prepared according to
the literature [19,20]. The structure of 2
was identified based on comparison of
the 1H and 13C NMR data with those
in the literature [19,20]. HR-ESI-MS

Journal of Asian Natural Products Research
673
m/z: 688.3326 [M þ H]þ (calcd for
NMR (400MHz, CDCl3) d 1.09 (3H, t,
J ¼ 7.2 Hz, NCH2CH3), 3.03, 3.20, 3.27,
3.72 (each 3H, s OCH3 £ 4), 3.04 (3H, s,
OMs), 4.75(1H, dd, J ¼ 12.8and 5.6 Hz, H-
3b), 4.87 (1H, d, J ¼ 4.8 Hz, H-14b), 7.46
(2H, t, J ¼ 7.6 Hz, H-30, 50), 7.58 (1H, t,
J ¼ 7.6 Hz, H-40), 8.03 (2H, d, J ¼ 7.6 Hz,
H-20, 60); for 13C NMR spectral data, see
Table 1; HR-ESI-MS m/z: 724.2994
[M þ H]þ (calcd for C35H50NO13S,
724.3003).
C36H50NO12, 688.3333).
3.2.2 Compound 3
Compound 3 (white amorphous powder,
390 mg, 92%) from compound 2 (400mg,
0.58mmol) was prepared according to the
literature [16]. The structure of 3 was
identifiedbasedoncomparisonofthe1Hand
13C NMR data with those in the literature
[16]. HR-ESI-MS m/z: 730.3446 [M þ H]þ
(calcd for C38H52NO13, 730.3439).
3.2.6 Compound 7
To a solution of aconitine (1, 200 mg,
0.31 mmol) in CH2Cl2 (5 ml), DMAP
(38 mg, 0.31 mmol), Et3N (0.1ml), and
TsCl (178 mg, 0.92 mmol) were added.
The mixturewas stirred atroomtemperature
for 20 h. Extraction (CHCl3, 5 ml £ 3),
drying (Na2SO4), and evaporation afforded
the residue, which was purifiedbyCC (silica
gel, CHCl3–MeOH, 100:1) to give com-
pound 7 (white amorphous powder, 211 mg,
3.2.3 Compound 4
Compound 4 (white amorphous powder,
102 mg, 97%) from compound 3 (100 mg,
0.14 mmol) was prepared according to the
literature [16]. Compound 4 was identified
based on comparison of the H and 13C
1
NMR data with those in the literature [16].
HR-ESI-MS m/z: 772.3547 [M þ H]þ
(calcd for C40H54NO14, 772.3544).
1
20
85%). 7: ½aꢀD þ 13.0 (c 0.5, CH2Cl2); H
NMR (400MHz, CDCl3) d 1.05 (3H, t,
J ¼ 7.2 Hz, NCH2CH3), 1.37 (3H, s, 8-
OAc), 2.43 (3H, s, 400-CH3), 3.03, 3.16, 3.17,
3.72 (each 3H, s, OCH3 £ 4), 4.04 (1H, d,
J ¼ 6.4 Hz, H-6b), 4.76 (1H, dd, J ¼ 12.8
and 5.6 Hz, H-3b), 4.84 (1H, d, J ¼ 4.8 Hz,
H-14b), 7.33 (2H, d, J ¼ 8.8 Hz, H-300, 500),
7.80 (2H, d, J ¼ 8.0 Hz, H-200, 600), 7.44 (2H,
t, J ¼ 7.6 Hz, H-30, 50), 7.55 (1H, t,
J ¼ 7.6 Hz, H-40), 8.01 (2H, d, J ¼ 7.2 Hz,
H-20, 60); for 13C NMR spectral data, see
Table 1; HR-ESI-MS m/z: 800.3314
[M þ H]þ (calcd for C41H54NO13S,
800.3316).
3.2.4 Compound 5
Compound 5 (white amorphous powder,
43 mg, 89%) from aconitine (1, 50 mg,
0.077 mmol) was prepared according to
the literature [21,22]. The structure of 5
was identified based on comparison of the
1H and 13C NMR data with those in the
literature [21,22]. HR-ESI-MS m/z:
628.3182
C34H46NO10, 628.3122).
[M þ H]þ
(calcd
for
3.2.5 Compound 6
Aconitine (1, 150 mg, 0.23 mmol) was
dissolved in CH2Cl2 (5ml), and DMAP
(28 mg, 0.23mmol), Et3N (0.1ml), and
MsCl (0.05 ml) were added. The mixture
was stirred at room temperature for 1 h.
Extraction (CHCl3, 5 ml £ 3), drying
(Na2SO4), and evaporation afforded the
residue, which was purified by CC (silica
gel, CHCl3–MeOH, 100:1) to give com-
pound 6 (white amorphous powder, 131 mg,
3.2.7 Compounds 8 and 9
To a solution of aconitine (1, 500 mg,
0.77 mmol) in acetone (20 ml), Jones
reagent (0.8 ml, 0.77 mmol) was added
dropwise under ice water bath. Then the
mixture was stirred at 08C for 0.5 h. The
reaction was quenched by anhydrous
NaHSO3. The mixture was neutralized
1
20
81%). 6: ½aꢀD þ 13.9 (c 1.1, CH2Cl2); H

674
X.-K. She et al.
with concentrated NH4OH. After filtration
andevaporationtoremovesolventandgivea
residue, the crude product was purified by
CC (silica gel, petroleum ether–EtOAc,
6:1) to afford compounds 8 (white amor-
phous powder, 300 mg, 61%) and 9 (white
amorphous powder, 85 mg, 18%). 8:
(3H, s, 8-OAc), 2.06 (3H, s, 3-OAc), 3.23,
3.25, 3.28, 3.76 (each 3H, s, OCH3 £ 4),
4.19(1H,d,J ¼ 6.8 Hz,H-6b),4.89(1H,dd,
J ¼ 10.8 and 6.8 Hz, H-3b), 5.07 (1H, d,
J ¼ 4.8 Hz, H-14b), 7.43(2H, t, J ¼ 7.6 Hz,
H-30, 50), 7.56 (1H, t, J ¼ 7.2 Hz, H-40), 8.04
(2H, d, J ¼ 7.2 Hz, H-20, 60); for 13C NMR
spectral data, see Table 1; HR-ESI-MS m/z:
½aꢀD þ 34.2 (c 0.5, CH2Cl2); 1H NMR
20
(400 MHz, CDCl3)
d
1.04 (3H, t,
686.3171
C36H48NO12, 686.3177).
[M þ H]þ
(calcd
for
J ¼ 7.2 Hz, NCH2CH3), 1.40 (3H, s, 8-
OAc), 3.19, 3.19, 3.22, 3.77 (each 3H, s,
OCH3 £ 4), 4.11 (1H, d, J ¼ 6.0 Hz, H-6b),
4.93 (1H, d, J ¼ 4.8 Hz, H-14b), 7.48 (2H,
t, J ¼ 7.6 Hz, H-30, 50), 7.59 (1H, t,
J ¼ 7.6 Hz, H-40), 8.04 (2H, d, J ¼ 7.2 Hz,
H-20, 60); for 13C NMR spectral data, see
Table 1; HR-ESI-MS m/z: 644.3074
[M þ H]þ (calcd for C34H46NO11,
3.2.9 Compound 11 and aconitine (1)
To a solution of compound 8 (170mg,
0.26 mmol) in MeOH (5 ml), NaBH4
(200mg, 5.26mmol) was added, and the
mixture was stirred at room temperature for
12h. After evaporation of MeOH, a residue
was obtained which was diluted in H2O
(5 ml), basified to pH 10 (conc. NH4OH),
extracted (CHCl3, 5 ml £ 3), and dried
(anhydrous Na2SO4). Evaporation of sol-
vent afforded the residue, which was
purified by CC (silica gel, cyclohexane–
acetone, 10:1) to give compound 11 (white
amorphous powder, 20 mg, 12%) and
aconitine (1, white amorphous powder,
20
644.3071). 9: ½aꢀD þ 75.4 (c 0.5,
1
CH2Cl2); H NMR (400MHz, CDCl3) d
1.00 (3H, t, J ¼ 7.2 Hz, NCH2CH3), 1.45
(3H, s, 8-OAc), 3.22, 3.29, 3.79 (each 3H, s,
OCH3 £ 3), 4.10 (1H, d, J ¼ 6.4 Hz, H-6b),
4.97 (1H, d, J ¼ 5.2 Hz, H-14b), 6.27 (1H,
d, J ¼ 10.4 Hz, H-2), 6.46 (1H, d,
J ¼ 10.0Hz, H-1), 7.48 (2H, t, J ¼ 7.6 Hz,
H-30, 50), 7.60 (1H, t, J ¼ 7.6 Hz, H-40), 8.04
(2H, d, J ¼ 7.2 Hz, H-20, 60); for 13C NMR
spectral data, see Table 1; HR-ESI-MS m/z:
20
122 mg, 73%). 11: ½aꢀD þ 11.6 (c 1.0,
1
CH2Cl2); H NMR (400MHz, CDCl3) d
612.2809
C33H42NO10, 612.2809).
[M þ H]þ
(calcd
for
1.04 (3H, t, J ¼ 7.2 Hz, NCH2CH3), 1.35
(3H, s, 8-OAc), 3.15, 3.25, 3.31, 3.72 (each
3H, s, OCH3 £ 4), 4.45 (1H, dd, J ¼ 5.2
and2.8 Hz, H-15b), 4.86(1H, d, J ¼ 4.8 Hz,
H-14b), 7.44 (2H, t, J ¼ 7.6 Hz, H-30, 50),
7.56 (1H, t, J ¼ 7.6 Hz, H-40), 8.02 (2H,
d, J ¼ 7.2 Hz, H-20, 60); for 13C NMR
spectral data, see Table 1; HR-ESI-MS m/z:
646.3231 [M þ H]þ(calcd for C34H48NO11,
646.3227).
3.2.8 Compound 10
To a solution of compound 2 (320mg,
0.46 mmol) in acetone (15 ml), Jones
reagent (4.5 ml, 2.30 mmol) was added
dropwise under ice water bath and the
solution was stirred at room temperature
for 12h. Then the reaction was quenched
by anhydrous NaHSO3. Basification (conc.
NH4OH), filtration, and evaporation to
remove the solvent could afford the residue,
which was purified by CC (silica gel,
cyclohexane–acetone, 15:1) to give com-
pound 10 (white amorphous powder,
3.2.10 Compound 12
Compound 11 (40 mg, 0.062 mmol) was
dissolved in pyridine (1 ml) and Ac2O
(0.1ml), the mixture was stirred at room
temperature for 24h. Removal of pyridine,-
diluting (H2O, 1 ml), basifying to pH 10
(conc. NH4OH), extraction (CHCl3, 2
ml £ 3), drying (anhydrous Na2SO4), and
20
264 mg, 83%). 10: ½aꢀD þ 4.7 (c 0.7,
CH2Cl2); 1H NMR (400 MHz, CDCl3)
d 1.04 (3H, t, J ¼ 7.2 Hz, NCH2CH3), 1.43

Journal of Asian Natural Products Research
675
evaporation afforded a residue, which was
isolated by CC (silica gel, petroleum ether–
acetone, 6:1) to give compound 12 (white
amorphous powder, 36 mg, 86%). 12:
NaBH4 (320 mg, 8.42 mmol) was added,
and then the mixture was refluxed for 14 h.
The reaction mixture was cooled to room
temperature and then quenched by the
addition of H2O (1 ml). The mixture was
concentrated to give a residue. After
basification (conc. NH4OH), the sub-
sequent mixture was extracted with
dichloromethane (15 ml £ 3). The organic
layers were combined and dried over
anhydrous Na2SO4, and the organic
solvents were removed under reduced
pressure to give the crude product, which
was purified by CC (silica gel, cyclohex-
ane–acetone, 2:1, with 1% Et2NH) to give
compounds 15 (white amorphous powder,
450 mg, 18%) and 16 (white amorphous
½aꢀD þ 27.2 (c 1.7, CH2Cl2); 1H NMR
20
(400 MHz, CDCl3)
d 1.06 (3H, t,
J ¼ 7.2 Hz, NCH2CH3), 1.36, 2.05 (each
3H, s, OAc £ 2), 2.62 (1H, ABq,
J ¼ 12.0 Hz, H-19), 2.59 (1H, ABq,
J ¼ 11.8Hz, H-19), 3.13, 3.18, 3.24, 3.74
(each 3H, s, OCH3 £ 4), 4.01 (1H, d,
J ¼ 6.8 Hz, H-6b), 4.46 (1H, dd, J ¼ 4.4
and 2.8 Hz, H-15b), 4.87(1H, d, J ¼ 4.8 Hz,
H-14b), 5.37 (1H, brs, W1/2 ¼ 4.8 Hz, H-
3a), 7.46 (2H, t, J ¼ 7.6 Hz, H-30, 50), 7.58
(1H, t, J ¼ 7.2 Hz, H-40), 8.03 (2H, d,
J ¼ 8.0 Hz, H-20, 60); for 13C NMR spectral
data, see Table 1; HR-ESI-MS m/z:
20
powder, 600 mg, 30%). 15: ½aꢀD 2 0.7 (c
688.3337
C36H50NO12, 688.3333).
[M þ H]þ
(calcd
for
1.2, CH2Cl2); 1H NMR (400 MHz, CDCl3)
d 1.12 (3H, t, J ¼ 7.2 Hz, NCH2CH3),
3.26, 3.29, 3.31, 3.71 (each 3H, s,
OCH3 £ 4), 3.77 (1H, dd, J ¼ 9.2 and
4.8 Hz, H-3b), 4.45 (1H, dd, J ¼ 10.4 and
6.4 Hz, H-15b), 4.92 (1H, d, J ¼ 5.2 Hz,
H-14b), 7.46 (2H, t, J ¼ 7.6 Hz, H-30, 50),
7.59 (1H, t, J ¼ 7.2 Hz, H-40), 8.04 (2H, d,
J ¼ 7.2 Hz, H-20, 60); for 13C NMR
spectral data, see Table 1; HR-ESI-MS
m/z: 588.3175 [M þ H]þ (calcd for
3.2.11 Compounds 13 and 14
Aconitine (1, 3000 mg, 4.65 mmol) was
subjected to pyrolysis under 1908C for
40 min in vacuum. The crude product was
purified by CC (silica gel, cyclohexane–
acetone, 5:1 with 1% Et2NH) to give
compounds 13 (white amorphous powder,
700 mg, 26%) and 14 (red amorphous
powder, 1600 mg, 59%). 13: 1H NMR
20
C32H46NO9, 588.3173). 16: ½aꢀD 2 1.6
(c 0.9, CH2Cl2); for 1H and 13C NMR
spectral data, see Table 3; HR-ESI-MS
m/z: 484.2908 [M þ H]þ (calcd for
C25H42NO8, 484.2910).
(400 MHz, CDCl3)
d 1.04 (3H, t,
J ¼ 7.2 Hz, NCH2CH3), 3.28, 3.30, 3.31,
3.64 (each 3H, s, OCH3 £ 4), 3.94 (1H, d,
J ¼ 6.8 Hz, H-6b), 5.19 (1H, d, J ¼ 4.4 Hz,
H-14b), 7.43 (2H, t, J ¼ 7.2 Hz, H-30, 50),
7.57 (1H, t, J ¼ 7.2 Hz, H-40), 7.96 (2H,
d, J ¼ 7.2 Hz, H-20, 60); for 13C NMR
spectral data, see Table 2; HR-ESI-MS
m/z: 586.3031 [M þ H]þ (calcd for
C32H44NO9, 586.3016). 14: for 1H and
13C NMR spectral data, see Table 2; HR-
ESI-MS m/z: 586.3023 [M þ H]þ (calcd
for C32H44NO9, 586.3016).
3.2.13 Compound 17
To a solution of compound 13 (300mg,
0.51 mmol) in anhydrous THF (15 ml),
LiAlH4 (44 mg, 3.78 mmol) was added
under ice water bath. The mixture was
warmed to room temperature and stirred
under argon for 7 h. H2O (1ml) was added
to quench the reaction. After filtering, the
mixture was concentrated to give a residue,
which was purified by CC (silica gel,
petroleum ether–acetone, 2:1, with 1%
Et2NH) to give compounds 17 (white
amorphous powder, 90mg, 36%) and 16
3.2.12 Compounds 15 and 16
To a solution of compound 13 (2500 mg,
4.27 mmol) in anhydrous THF (25 ml),

676
X.-K. She et al.
20
(120mg, 48%). 17: ½aꢀD þ 4.2 (c 0.9,
layers were combined and dried over
anhydrous Na2SO4, and the organic solvents
were removed under reduced pressure to
give the crude product, which was isolated
by CC (silica gel, cyclohexane–acetone,
2:1, with 1% Et2NH) to give compounds 19
(white amorphous powder, 300 mg, 11%)
and 20 (white amorphous powder, 1000mg,
1
CH2Cl2); H NMR (400MHz, CDCl3) d
1.08 (3H, t, J ¼ 6.8 Hz, NCH2CH3), 2.75
(1H, s, H-17), 3.01 (1H, dd, J ¼ 9.2 and
6.4 Hz, H-1b), 3.22, 3.29, 3.30, 3.60 (each
3H, s, OCH3 £ 4), 3.70 (1H, d, J ¼ 4.2 Hz,
H-14b), 3.94 (1H, d, J ¼ 6.4 Hz, H-6b); for
13C NMR spectral data, see Table 1; HR-
ESI-MS m/z: 484.2914 [M þ H]þ (calcd
for C25H42NO8, 484.2910).
1
20
43%). 19: ½aꢀD 2 7.6 (c 0.4, CH2Cl2); H
NMR (400MHz, CDCl3) d 1.10 (3H, t,
J ¼ 6.8 Hz, NCH2CH3), 3.28, 3.29, 3.30,
3.62 (each 3H, s, OCH3 £ 4), 3.76 (1H, dd,
J ¼ 10.2 and 5.2 Hz, H-3b), 3.87 (1H, d,
J ¼ 6.4 Hz, H-6b), 4.62 (1H, t, J ¼ 9.2 Hz,
H-15b), 5.12 (1H, d, J ¼ 4.0 Hz, H-14b),
7.47(2H, t, J ¼ 7.6 Hz, H-30, 50), 7.61(1H, t,
J ¼ 7.6 Hz, H-40), 8.01 (2H, d, J ¼ 7.2 Hz,
H-20, 60); for 13C NMR spectral data, see
Table 1; HR-ESI-MS m/z: 588.3166
[M þ H]þ (calcd for C32H46NO9,
3.2.14 Compound 18
Compound 17 (50 mg, 0.104 mmol) was
dissolved in Ac2O (2 ml), and p-TsOH
(33 mg, 0.191 mmol) was added. The
mixture was stirred for 48 h at room
temperature. After basification (conc.
NH4OH), the subsequent mixture was
extracted with dichloromethane (2 ml £ 3).
Theorganiclayerswerecombinedanddried
over anhydrous Na2SO4, and the organic
solvents were removed under reduced
pressure to give compound 18 (white
amorphous powder, 59 mg, 92%). 18:
20
588.3173). 20: ½aꢀD 2 44.6 (c 1.8,
CH2Cl2); for 1H NMR and 13C NMR
spectral data, see Table 3; HR-ESI-MS
m/z: 484.2912 [M þ H]þ (calcd for
C25H42NO8, 484.2910).
½aꢀD 2 10.7 (c 1.8, CH2Cl2); 1H NMR
20
(400 MHz, CDCl3)
d 1.09 (3H, t,
J ¼ 6.8 Hz, NCH2CH3), 2.05, 2.06, 2.07,
2.12 (each 3H, s, OAc £ 4), 3.20, 3.21, 3.29,
3.30 (each 3H, s, OCH3 £ 4), 3.91 (1H, d,
J ¼ 6.8 Hz, H-6b), 3.90 (1H, d, J ¼ 7.6Hz,
H-16a), 4.86 (1H, dd, J ¼ 12.0, 6.0 Hz, H-
3b), 5.15 (1H, dd, J ¼ 8.4 and 4.4Hz, H-
15a), 5.32 (1H, d, J ¼ 4.8Hz, H-14b); for
13C NMR spectral data, see Table 1; HR-
ESI-MS m/z: 652.3344 [M þ H]þ (calcd
for C33H50NO12, 652.3333).
Acknowledgments
We are grateful to the National Natural Science
Foundation of China (No. 81072550) for
financial support of this research.
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