Isolation, identification, semi-synthesis of aziditaxel derivatives and their biological evaluation

Article abstract of DOI:10.1080/10286020.2012.672322

Two new taxoids (5 and 6) were obtained by isolating impurities in aziditaxel, and their structures were characterized based on data analysis of ¹H NMR, ¹³C NMR, HPLC-MS, and through comparison with literature. In order to test their cytotoxicities against human nonsmall lung cancer cell lines (A549), sufficient amounts of compounds 5 and 6 were obtained by semi-synthesis and both of them showed equipotent cytotoxiesty compared with taxol, docetaxel, and aziditaxel.

Full text of DOI:10.1080/10286020.2012.672322

Journal of Asian Natural Products Research
Vol. 14, No. 5, May 2012, 463–475
Isolation, identification, semi-synthesis of aziditaxel derivatives
and their biological evaluation
Shu-En Zhang, Jia-Yi Tao, Ying Zhao, Shao-Rong Wang, Di Zhou
and Wei-Shuo Fang*
State Key Laboratory of Bioactive Substance and Function of Natural Medicines, Institute of
Materia Medica, Chinese Academy of Medical Sciences and Peking Union Medical College,
Beijing 100050, China
(Received 11 December 2011; final version received 29 February 2012)
Two new taxoids (5 and 6) were obtained by isolating impurities in aziditaxel, and their
1
structures were characterized based on data analysis of H NMR, 13C NMR, HPLC-
MS, and through comparison with literature. In order to test their cytotoxicities against
human nonsmall lung cancer cell lines (A549), sufficient amounts of compounds 5 and
6 were obtained by semi-synthesis and both of them showed equipotent cytotoxiesty
compared with taxol, docetaxel, and aziditaxel.
Keywords: taxol; docetaxel; aziditaxel; semi-synthesis
1. Introduction
mannine (3) and it is effective to the MDR
of ovarian carcinoma [8] (Figure 1).
Cancer is one of lethal diseases for human
being leading to mass mortality all over
the world [1,2]. Paclitaxel (1) and
docetaxel (2) are among the most widely
used chemotherapeutic drugs against ovar-
ian, breast, and lung cancers, as well as
Kaposi’s sarcoma [3–5]. Their action
mechanism lies on binding to the tubulin
subunit, accelerating the polymerization,
inhibiting their depolymerization, and
leading to apoptosis finally [6]. Though
paclitaxel and docetaxel have gained great
success in clinical practice, they still have
many drawbacks including low avail-
ability in the nature, poor water solubility,
and especially severe multidrug resistance
(MDR). MDR to paclitaxel and docetaxel
has been one of the major causes in terms
of chemotherapy failure. Aziditaxel (4) is
one of new taxoids which was obtained
through semi-synthesis [7] from cephalo-
By the method of HPLC we found that
there were two main impurities in
aziditaxel and their retention times were
41.062 and 44.961 min, respectively, in
our HPLC condition. We isolated them
and named them as 41m (5) and 45m (6).
We also identified their structures
1
(Figure 2) based on data analysis of H
NMR, 13C NMR, HPLC-MS, and through
comparison with literature [9]. In order to
further determine their structures and test
their anti-tumor activities, we synthesized
sufficient 41m and 45m.
2. Chemical synthesis of compounds
41m and 45m
The synthesis of compound 5 is illustrated
in Scheme 1 [10,11]. 7-TES-baccatin III
was first reacted with N-isovaleryl-b-
lactam 7 through the Ojima–Holton
coupling protocol in the presence of
*Corresponding author. Email: wfang@imm.ac.cn
ISSN 1028-6020 print/ISSN 1477-2213 online
q 2012 Taylor & Francis
http://dx.doi.org/10.1080/10286020.2012.672322
http://www.tandfonline.com

464
S.-E. Zhang et al.
O
R2O
O
R1
O
NH
3'
OR4
10
2'
O
7
2
OH
HO
H
O
O
O
O
O
R3
1 R1 = Ph, R2 = Ac, R3 = Ph, R4 = H
2 R1 = t-Buo, R2 = H, R3 = Ph, R4 = H
3 R1 = Tigloyl, R2 = Ac, R3 = Ph, R4 = H
4 R1 = Tigloyl, R2 = H, R3 = m-N3-Ph, R4 = Propionyl
Figure 1. Structures of compounds 1–4.
bis(trimethyl-silyl) amine lithium salt
(LHMDS) in THF, to afford the corre-
sponding taxoid 8. The benzoyl in 8 was
removed by hydrolysis with benzyltri-
methylammonium hydroxide (Triton B) in
CH2Cl2 to afford 9. The 2-OH in 9 was
esterized with 3-azidobenzoic acid in the
presence of dicyclohexylcarbodiimide
(DCC) and 4-dimethylaminopyridine
(DMAP) in toluene to afford 10. Depro-
tection of silyl ether groups of 10 at C-20
and C-7 was realized by HF–pyridine in
the solvent of pyridine and acetonitrile
(1:1) to afford 11. After the hydroxyl
group at C-20 position was selectively
protected as a TBS ester, the acetyl at C-10
was removed by 85% hydrazine hydrate in
ethanol at 08C to afford dihydroxyl
compound 13. The 10-hydroxyl group
of 13 was selectively protected by
TMS using bis(trimethylsilyl)-trifluoro-
acetamide (BSTFA) in THF, with catalytic
amounts of LHMDS. The 7-hydroxyl
group of 14 was reacted with propionic
anhydride, in the presence of triethylamine
as acid trapping agent and DMAP as
catalyst. Finally, the silyl groups of TMS
and TBS in 15 were removed by HF–
pyridine in pyridine and acetonitrile at
room temperature to furnish compound 5.
The synthesis of compound 6, which
was prepared from cephalomannine (3), is
illustrated in Scheme 2 [10–13]. The
hydroxyl groups of cephalomannine at the
O
O
HO
O
O
O
NH
O
O
O
O
NH
O
O
OH
O
OH
O
HO
H
O
O
OH
O
O
HO
H
O
O
O
O
N3
O
N3
5
6
Figure 2. Structures of compounds 5 and 6.

Journal of Asian Natural Products Research
465
O
AcO
O
AcO
AcO
TBSO
O
O
O
O
NH
O
O
Si
NH
O
O
Si
O
Si
N
HO
O
O
O
7
a
b
OTBS
OTBS
HO
H
O
O
HO
HO
H
H
O
O
O
O
O
O
HO
O
O
O
O
O
9
8
7-TES-baccatin III
O
O
O
AcO
AcO
AcO
O
O
O
NH
O
NH
O
NH
O
O
Si
OH
OH
O
O
O
OTBS
10
OH
OTBS
12
e
HO
O
HO
H
d
H
O
HO
O
H
O
c
O
O
O
O
O
O
O
O
O
O
O
N3
N3
N3
11
O
O
O
TMSO
HO
O
O
NH
O
NH
OH
OH
O
O
TMSO
O
O
NH
O
OTBS
O
OTBS
HO
O
H
HO
O
H
O
h
O
O
g
O
O
O
f
O
O
O
O
OTBS
15
HO
H
N3
O
N3
O
O
O
13
14
O
N3
O
HO
O
NH
O
O
O
O
i
OH
HO
O
H
O
O
O
O
N3
5
Scheme 1. Synthesis of compound 5. Reagents and conditions: (a) LHMDS, THF, 2408C;
(b) Triton B, CH2Cl2, 2308C; (c) DCC, DMAP, 3-azidobenzoic acid, toluene, 708C; (d) HF,
pyridine, CH3CN, 258C; (e) TBSCl, imidazole, DMF, 408C; (f) NH2NH2.H2O, C2H5OH, 08C;
(g) BSTFA, LHMDS, THF, 2208C; (h) propionic anhydride, triethylamine, DMAP, THF, 258C; and
(i) HF, pyridine, CH3CN, 258C.
positions of 20 and 7 were protected,
respectively, by TBS and TES when
subsequently treated with t-butyldimethyl-
chlorosilane (TBSCl) and then triethyl-
chlorosilane (TESCl) in DMF to afford 16.
The follow-up synthesis steps k–o were
almost as same as the synthesis steps b–f
(Scheme 1), respectively, until the inter-
mediate 21 was obtained. The hydroxyl
group of 21 at the position of C-10 was
selectively acylated by propionic anhy-
dride catalyzed by anhydrous CeCl3 to
afford 22. The role of CeCl3 should be the
catalyst of the acylation at the C-10
hydroxyl group. Then the hydroxyl group
of 22 at the position of C-7 became
epimerized through retroaldol–aldol reac-
tion [12,13] in the presence of 1,8-
diazabicyclo[5.4.0]undec-7-ene (DBU) to
afford 23. At last, the silyl groups of TBS
were removed by HF–pyridine in pyridine
and acetonitrile and the target compound 6
was afforded (Scheme 2).
3. Results and discussion
During the isolation of impurities in
aziditaxel, two taxoids were characterized
as the main impurities. First, we identified
the structures of the two compounds based
on spectroscopic data (1H NMR, 13C
NMR, and MS). Then we synthesized
those compounds and characterized them

466
S.-E. Zhang et al.
O
O
O
AcO
AcO
AcO
O
O
O
NH
O
O
NH
NH
O
OH
O
O
Si
O
Si
O
O
OTBS
O
j
k
l
OH
OTBS
HO
H
O
HO
H
HO
H
O
O
O
O
HO
O
O
O
O
O
O
O
3
16
O
17
O
O
AcO
O
AcO
AcO
O
O
NH
O
NH
O
OH
NH
O
O
Si
OH
O
O
O
OH
OTBS
o
n
OTBS
m
HO
H
HO
H
O
O
H
HO
O
O
O
O
O
O
O
O
O
O
O
O
O
N3
19
N3
18
N3
20
O
O
O
HO
O
O
O
O
O
O
NH
O
O
OH
O
NH
O
NH
O
OH
OH
O
O
O
p
q
r
OTBS
OTBS
OTBS
HO
H
O
HO
H
O
HO
O
H
O
O
O
O
O
O
O
O
O
O
O
N3
N3
23
N3
22
21
O
O
O
O
NH
O
OH
O
O
OH
HO
H
O
O
O
O
N3
6
Scheme 2. Synthesis of compound 6. Reagents and conditions: (j) TBSCl, imidazole, then TESCl,
imidazole, DMF, 408C; (k) Triton B, CH2Cl2, 2308C; (l) DCC, DMAP, 3-azidobenzoic acid,
toluene, 708C; (m) HF, pyridine, CH3CN, 258C; (n) TBSCl, imidazole, DMF, 408C;
(o) NH2NH2.H2O, C2H5OH, 08C; (p) propionic anhydride, CeCl3, THF, 258C; (q) DBU, toluene,
708C; and (r) HF, pyridine, CH3CN, 258C.
1
by the comparison of the spectra of H
NMR, 13C NMR, and MS with those of
isolated impurities. Since we obtained
sufficient amounts of 41m and 45m, we
could test their in vitro anti-tumor
activities, and found that their cytotoxi-
cities against human nonsmall lung cancer
cell lines were equipotent compared with
those of taxol, docetaxel, and aziditaxel
(Table 1). Their activities against other
tumor cells will be further tested.
the activities or toxicities of any impurity
cannot be ignored.
4. Experimental
4.1. General experimental procedures
Optical rotations were measured on a
PerkinElmer Polarimeter 341LC (Perki-
nElmer, Waltham, MA, USA) using 10 cm
cells and the sodium D line (589 nm) at
208C and concentration indicated. NMR
spectra were determined with Mercury
300, 400 MHz or INOVA 500 MHz
spectrometers (Varian Medical Systems,
Inc., Palo Alto, CA, USA) in CDCl3. J and
d values are given in Hz and ppm,
In conclusion, two new taxoids were
found by isolation of impurities in
aziditaxel and they also showed strong
cytotoxic activity, which suggested that

Journal of Asian Natural Products Research
467
respectively. Mass spectra (ESI-MS) were
recorded on an Agilent LC–MSD-Trap-
SL instrument (Agilent Technologies,
Santa Clara, CA, USA). All chemicals
other than solvents were obtained from
Aldrich Chemical Co. and used without
further purification. All reactions were
monitored by TLC (silica gel, GF254) with
UV light and H2SO4–anisaldehyde spray
visualization. Column chromatography
was conducted over silica gel 60 (200–
300 mesh), (Qingdao Haiyang Chemical
Co., Qingdao, China).
4.2. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-7-O-
(triethylsilyl)-taxol (8)
7-O-Triethylsilyl-10-deacetylbacctin III
(137 mg, 0.207 mmol) was dissolved in
6.8 ml THF, then 1.0 M solution of
LHMDS in THF (0.415 ml, 0.415 mmol)
was added under N2 atmosphere at 2408C.
The mixture was stirred for 10 min at this
temperature. b-Lactam
7
(150 mg,
0.415 mmol) was added to the mixture,
then the mixture was stirred for another
60 min at 2408C. Saturated aqueous
NH4Cl was added and the aqueous layer
was extracted with EtOAc. The combined
extracts were dried over anhydrous Na2SO4
and concentrated in vacuo. The residue was
purified by chromatography on silica gel
(petroleum ether:EtOAc ¼ 5:1) to afford 8
(186 mg, 84.7% yield) as a white solid. 1H
NMR (300 MHz, CDCl3) d 8.13 (d,
J ¼ 7.2 Hz, 2H), 7.60 (t, J ¼ 7.2 Hz, 1H),
7.51 (t, J ¼ 7.2 Hz, 2H), 7.42–7.21 (m,
5H), 6.47 (s, 1H), 6.32 (d, J ¼ 9.0 Hz, 1H),
6.25 (t, J ¼ 8.7 Hz, 1H), 5.72 (d,
J ¼ 6.9 Hz, 1H), 5.58 (d, J ¼ 9.0 Hz, 1H),
4.96 (d, J ¼ 8.1 Hz, 1H), 4.57 (d,
J ¼ 2.1 Hz, 1H), 4.48 (dd, J ¼ 10.5,
6.6 Hz, 1H), 4.33 (d, J ¼ 8.4 Hz, 1H),
4.21 (d, J ¼ 8.4 Hz, 1H), 3.85 (d,
J ¼ 6.9 Hz, 1H), 2.55 (s, 3H), 2.61–2.47
(m, overlapped 1H), 2.39 (dd, J ¼ 15.1,
9.7 Hz, 1H), 2.19 (s, 3H), 2.16–2.08 (m,
3H), 2.02 (s, 3H), 2.07–1.99 (m, 2H), 1.71

468
S.-E. Zhang et al.
(s, 3H), 1.25 (s, 3H), 1.23 (s, 3H), 1.01–
0.83 (m, 15H), 0.78 (s, 9H), 0.58 (q,
J ¼ 7.8 Hz, 6H), 20.09 (s, 3H), 20.28 (s,
3H); 13C NMR (75 MHz, CDCl3) d 201.7,
171.9, 171.4, 170.1, 169.3, 167.1, 140.2,
138.5, 133.6, 133.6, 130.2, 129.2, 128.7,
128.6, 127.8, 126.4, 84.2, 81.2, 78.8, 77.1,
76.6, 75.2, 74.9, 72.2, 71.4, 58.4, 55.1, 46.6,
45.8, 43.4, 37.2, 35.5, 26.5, 26.1, 25.5, 23.1,
22.4, 22.3, 21.5, 20.9, 18.2, 14.2, 10.1, 6.7,
5.3, 25.4, 25.9; ESI-MS: m/z 1062.5
[M þ H]þ.
50.5, 45.8, 43.4, 36.6, 35.2, 26.1, 25.4,
25.1, 22.8, 22.3, 22.2, 21.6, 20.7, 18.1,
15.4, 14.3, 6.7, 4.9, 25.4, 25.9; ESI-MS:
m/z 958.6 [M þ H]þ; 980.5 [M þ Na]þ.
4.4. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-2-
m-N3-benzoyl-7-O-(triethylsilyl)-taxol
(10)
3-Azidobenzoic acid (485 mg, 2.975
mmol), DCC (644 mg, 3.124 mmol), and
DMAP (7 mg, 0.060 mmol) were dissolved
in 11.4 ml toluene. The mixture was stirred
for 30 min at room temperature and 9 was
added. Then the reaction mixture was
stirred for 72 h. The reaction mixture was
filtered and washed by ethyl ether. The
filtrate was concentrated in vacuo and the
residue was purified by chromatography on
silica gel (petroleum ether:EtOAc ¼ 5:1)
to afford 10 (562 mg, 85.7% yield) as a
white solid. 1H NMR (300 MHz, CDCl3) d
7.89 (d, J ¼ 7.8 Hz, 1H), 7.80 (s, 1H), 7.47
(t, J ¼ 7.8 Hz, 1H), 7.39–7.26 (m, 5H),
7.20–7.24 (m, 1H), 6.45 (s, 1H), 6.31 (d,
J ¼ 9.0 Hz, 1H), 6.18 (t, J ¼ 8.7 Hz, 1H),
5.69 (d, J ¼ 6.9 Hz, 1H), 5.54 (d,
J ¼ 9.0 Hz, 1H), 4.95 (d, J ¼ 8.4 Hz, 1H),
4.52 (s, 1H), 4.46 (dd, J ¼ 10.5, 6.6 Hz,
1H), 4.32 (d, J ¼ 8.4 Hz, 1H), 4.18 (d,
J ¼ 8.4 Hz, 1H), 3.84 (d, J ¼ 6.9 Hz, 1H),
2.61–2.46 (m, overlapped, 1H), 2.52 (s,
3H), 2.37 (dd, J ¼ 15.3, 9.6 Hz, 1H), 2.23–
2.10 (m, 3H), 2.16 (s, 3H), 2.00 (s, 3H),
1.96–1.85 (m, 2H), 1.68 (s, 3H), 1.22 (s,
3H), 1.20 (s, 3H), 0.93 (t, J ¼ 7.8 Hz, 9H),
0.87 (d, J ¼ 5.1 Hz, 6H), 0.77 (s, 9H), 0.57
(q, J ¼ 7.8 Hz, 6H), 20.11 (s, 3H), 20.29
(s, 3H); 13C NMR (75 MHz, CDCl3) d
201.6, 171.9, 171.4, 170.0, 169.2, 166.0,
140.7, 140.3, 138.5, 133.6, 131.0, 130.2,
128.5, 127.8, 126.8, 126.5, 124.2, 120.1,
84.2, 81.2, 78.7, 76.4, 75.3, 75.1, 74.9, 72.1,
71.6, 58.3, 55.1, 46.5, 45.8, 43.3, 37.2, 35.4,
26.4, 26.0, 25.5, 23.0, 22.4, 22.3, 21.4, 20.8,
18.1, 14.2, 10.0, 6.7, 5.2, 25.4, 25.8; ESI-
MS: m/z 1103.5 [M þ H]þ; 1125.5
[M þ Na]þ.
4.3. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-7-
O-(triethylsilyl)-taxol (9)
To a solution of 8 (824 mg, 0.776 mmol) in
27 ml CH2Cl2 was added 40% solution of
Triton B in CH3OH (0.68 ml, 1.552 mmol)
at 2308C and the solution was stirred for
3 h. Then the reaction was quenched by
addition of aqueous NH4Cl, and the
aqueous solution was extracted by
CH2Cl2. The combined extracts were
dried with anhydrous Na2SO4 and con-
centrated in vacuo. The residue was
purified by chromatography on silica gel
(petroleum ether:EtOAc ¼ 2:1) to afford 9
(570 mg, 76.8% yield) as a white solid. 1H
NMR (300 MHz, CDCl3) d 7.38–7.29 (m,
3H), 7.15 (d, J ¼ 7.2 Hz, 2H), 6.35 (d,
J ¼ 9.0 Hz, 1H), 6.30 (s, 1H), 6.24 (t,
J ¼ 8.7 Hz, 1H), 5.46 (d, J ¼ 9.0 Hz, 1H),
4.41 (s, 1H), 4.31 (d, J ¼ 11.4 Hz, 1H),
4.22 (d, J ¼ 9.3 Hz, 1H), 4.12 (d,
J ¼ 6.6 Hz, 1H), 3.95 (dd, J ¼ 11.4,
3.3 Hz, 1H), 3.68 (d, J ¼ 11.4 Hz, 1H),
3.29 (d, J ¼ 6.3 Hz, 1H), 2.63 (dd,
J ¼ 14.4, 9.3 Hz, 1H), 2.32 (s, 3H), 2.15
(s, 3H), 2.28–2.01 (m, 4H), 2.14 (s, 3H),
1.89 (s, 3H), 1.92–1.80 (m, 2H), 1.26 (s,
3H), 1.25 (s, 3H), 1.08 (s, 3H), 0.91 (m,
15H), 0.73 (s, 9H), 0.53 (q, J ¼ 7.8 Hz,
6H), 20.16 (s, 3H), 20.35 (s, 3H); 13C
NMR (75 MHz, CDCl3) d 202.0, 172.0,
171.5, 171.3, 169.2, 139.4, 138.5, 136.4,
128.5, 127.8, 126.2, 95.0, 85.8, 76.2, 75.4,
75.0, 72.0, 71.3, 70.8, 70.5, 55.4, 55.0,

Journal of Asian Natural Products Research
469
4.5. 30N-Debenzoyl-30N-isovaleryl-2-
debenzoyl-2-m-N3-benzoyl-taxol (11)
mixture was then washed with water and
brine, dried over Na2SO4, and concen-
trated in vacuo. The residue was purified
by chromatography on silica gel (pet-
roleum ether:EtOAc ¼ 3:1) to afford 12
(442 mg, 94.7% yield) as a white solid. 1H
NMR (300 MHz, CDCl3) d 7.93 (d,
J ¼ 7.8 Hz, 1H), 7.84 (s, 1H), 7.52 (t,
J ¼ 7.8 Hz, 1H), 7.45–7.28 (m, 5H),
7.24–7.21 (m, 1H), 6.36 (d, J ¼ 8.7 Hz
1H), 6.34 (s, 1H), 6.14 (t, J ¼ 9.0 Hz, 1H),
5.72 (d, J ¼ 7.2 Hz, 1H), 5.59 (d,
J ¼ 8.7 Hz, 1H), 5.02 (d, J ¼ 8.1 Hz,
1H), 4.55 (d, J ¼ 1.8 Hz, 1H), 4.47 (dd,
J ¼ 10.5, 6.6 Hz, 1H), 4.37 (d, J ¼ 8.4 Hz,
1H), 4.23 (d, J ¼ 8.4 Hz, 1H), 3.87 (d,
J ¼ 7.2 Hz, 1H), 2.63–2.49 (m, over-
lapped, 2H), 2.55 (s, 3H), 2.42 (dd,
J ¼ 15.3, 9.6 Hz, 1H), 2.30–2.13 (m,
2H), 2.26 (s, 3H), 2.10–2.01 (m, 1H),
1.99–1.85 (m, 1H), 1.93 (s, 3H), 1.71 (s,
3H), 1.31 (s, 3H), 1.28 (s, 3H), 1.18 (s,
3H), 0.93 (d, J ¼ 5.1 Hz, 6H), 0.82 (s, 9H),
20.08 (s, 3H), 20.25 (s, 3H); 13C NMR
(75 MHz, CDCl3) d 203.7, 171.9, 171.4,
171.2, 170.0, 166.0, 142.6, 140.7, 138.4,
132.8, 130.9, 130.2, 128.6, 127.9, 126.8,
126.5, 124.3, 120.1, 84.4, 81.2, 79.0, 76.4,
75.3, 75.1, 74.9, 72.1, 71.6, 58.5, 55.1,
45.8, 45.4, 43.2, 35.7, 35.5, 29.2, 26.6,
26.0, 25.5, 23.0, 22.4, 22.3, 22.2, 20.8,
14.9, 9.5, 25.5, 25.8; ESI-MS: m/z 989.5
[M þ H]þ; 1011.5 [M þ Na]þ.
To a solution of 10 (562 mg, 0.510 mmol)
in 4.1 ml pyridine and 15.5 ml acetonitrile
was added dropwise 40% solution of HF in
water (2.4 ml) at 08C. The mixture was
stirred at room temperature for 12 h. The
reaction was quenched with saturated
aqueous NaHCO3 and the aqueous phase
was extracted by EtOAc. The combined
extracts were dried with anhydrous
Na2SO4 and concentrated in vacuo. The
crude product was purified by column
chromatography on silica gel (petroleum
ether:EtOAc ¼ 1:1) to afford 11 (413 mg,
1
92.6% yield) as a white solid. H NMR
(300 MHz, CDCl3) d 7.87 (d, J ¼ 7.8 Hz,
1H), 7.78 (s, 1H), 7.47 (t, J ¼ 7.8 Hz, 1H),
7.42–7.27 (m, 5H), 7.21–7.24 (m, 1H),
6.31 (d, J ¼ 9.0 Hz, 1H), 6.27 (s, 1H), 6.14
(t, J ¼ 9.0 Hz, 1H), 5.66 (d, J ¼ 6.9 Hz,
1H), 5.53 (d, J ¼ 9.0 Hz, 1H), 4.92 (d,
J ¼ 8.7 Hz, 1H), 4.63 (s, 1H), 4.38 (dd,
J ¼ 10.5, 6.6 Hz, 1H), 4.28 (d, J ¼ 8.4 Hz,
1H), 4.16 (d, J ¼ 8.4 Hz, 1H), 3.78 (d,
J ¼ 6.9 Hz, 2H), 2.61–2.47 (m, 2H), 2.30
(s, 3H), 2.28–2.19 (m, 1H), 2.22 (s, 3H),
2.00–1.96 (m, 2H), 1.89–1.78 (m, 2H),
1.81 (s, 3H), 1.66 (s, 3H), 1.24 (s, 3H),
1.14 (s, 3H), 0.88 (d, J ¼ 5.1 Hz, 6H); 13
C
NMR (75 MHz, CDCl3) d 203.6, 173.0,
172.4, 171.2, 170.2, 165.8, 142.0, 140.6,
138.1, 133.0, 130.9, 130.2, 128.9, 128.2,
127.0, 126.8, 124.3, 120.0, 84.4, 81.1,
78.7, 76.3, 75.5, 75.4, 72.9, 72.4, 72.0,
58.5, 54.6, 45.8, 45.5, 43.2, 35.6, 34.7,
26.7, 26.1, 22.6, 22.3, 22.3, 21.8, 20.8,
14.7, 9.5; ESI-MS: m/z 875.4 [M þ H]þ.
4.7. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-2-
m-N3-benzoyl-10-deacetyl-taxol (13)
To a solution of 12 (442 mg, 0.447 mmol)
in 8.8 ml ethanol was added dropwise 85%
hydrazine hydrate (0.174 ml, 3.075 mmol)
at 08C and the mixture was stirred for 12 h
at the same temperature. The reaction was
quenched with saturated aqueous NH4Cl
and extracted with EtOAc. The combined
organic layers were washed with water and
brine, dried over Na2SO4, filtered, and
concentrated in vacuo. The residue was
purified by chromatography on silica gel
4.6. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-2-
m-N3-benzoyl-taxol (12)
To a solution of 11 (413 mg, 0.472 mmol)
and imidazole (193 mg, 2.832 mol) in
4.0 ml DMF was added TBSCl (391 mg,
2.596 mmol) at room temperature. The
mixture was stirred for 4 h at 408C and
then diluted with EtOAc. The reaction

470
S.-E. Zhang et al.
(petroleum ether:EtOAc ¼ 2:1) to afford
13 (387 mg, 91.5% yield) as a white solid.
1H NMR (300 MHz, CDCl3) d 7.90 (d,
J ¼ 7.8 Hz, 1H), 7.81 (s, 1H), 7.49 (t,
J ¼ 7.8 Hz, 1H), 7.41–7.24 (m, 5H),
7.24–7.21 (m, 1H), 6.40 (d, J ¼ 9.0 Hz,
1H), 6.19 (t, J ¼ 8.7 Hz, 1H), 5.66 (d,
J ¼ 6.9 Hz, 1H), 5.51 (d, J ¼ 9.0 Hz, 1H),
5.19 (s, 1H), 4.94 (d, J ¼ 9.0 Hz, 1H), 4.51
(s, 1H), 4.32 (d, J ¼ 8.4 Hz, 1H), 4.23 (m,
1H), 4.19 (d, J ¼ 8.4 Hz, 1H), 3.91 (d,
J ¼ 6.9 Hz, 1H), 2.50 (s, 3H), 2.50 (m,
overlapped 1H), 2.35 (dd, J ¼ 15.0,
9.6 Hz, 1H), 2.19 (d, J ¼ 6.6 Hz, 2H),
2.12–1.99 (m, 2H), 1.97–1.89 (m, 1H),
1.89 (s, 3H), 1.68 (s, 3H), 1.22 (s, 3H),
1.09 (s, 3H), 0.90 (d, J ¼ 5.1 Hz, 6H), 0.78
7.89 (d, J ¼ 7.8 Hz, 1H), 7.81 (s, 1H), 7.49
(t, J ¼ 7.8 Hz, 1H), 7.42–7.27 (m, 5H),
7.24–7.21 (m, 1H), 6.45 (d, J ¼ 9.0 Hz,
1H), 6.45 (m, overlapped 1H), 6.16 (t,
J ¼ 9.0 Hz, 1H), 5.70 (d, J ¼ 7.2 Hz, 1H),
5.53 (d, J ¼ 9.0 Hz, 1H), 5.22 (s, 1H), 4.97
(d, J ¼ 8.4 Hz, 1H), 4.51 (s, 1H), 4.33 (d,
J ¼ 8.4 Hz, 1H), 4.21 (d, J ¼ 8.4 Hz, 1H),
4.21 (m, overlapped, 1H), 3.95 (d,
J ¼ 7.2 Hz, 1H), 2.70–2.58 (m, 1H), 2.51
(s, 3H), 2.38 (dd, J ¼ 15.0, 9.6 Hz, 1H),
2.26–2.15(m, 2H),2.11(m, 1H), 2.07–1.95
(m, 1H), 1.93–1.77 (m, 1H), 1.93 (s, 3H),
1.75 (s, 3H), 1.27 (s, 6H), 0.90 (d,
J ¼ 5.1 Hz, 6H), 0.79 (s, 9H), 0.17 (s, 9H),
20.11 (s, 3H), 20.27 (s, 3H); 13C NMR
(75 MHz, CDCl3) d 208.9, 172.2, 171.7,
169.9, 166.0, 140.7, 138.4, 137.4, 135.3,
131.0, 130.2, 128.6, 127.9, 126.8, 126.5,
124.3, 120.0, 84.3, 81.3, 78.8, 75.6, 75.2,
75.2, 72.0, 71.9, 71.8, 57.5, 55.2, 46.6, 45.8,
43.2, 37.0, 35.6, 26.2, 26.1, 25.5, 23.1, 22.4,
22.3, 20.9, 18.2, 14.0, 10.0, 0.5, 25.5,
25.8; ESI-MS: m/z 1041.4 [M þ Na]þ.
(s, 9H), 20.10 (s, 3H), 20.29 (s, 3H); 13
C
NMR (75 MHz, CDCl3) d 211.1, 172.1,
171.3, 169. 9, 165.7, 140.6, 138.5, 138.4,
135.7, 131.0, 130.2, 128.5, 127.8, 126.7,
126.4, 124.2, 120.0, 84.2, 81.1, 78.5, 77.2,
76.4, 75.4, 75.0, 74.3, 71.7, 57.5, 55.0,
46.2, 45.8, 43.1, 36.6, 35.8, 26.2, 26.0,
25.4, 22.9, 22.3, 22.2, 20.9, 18.1, 14.2, 9.8,
25.4, 25.8; ESI-MS: m/z 969.5
[M þ Na]þ.
4.9. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2- debenzoyl-2-
m-N3-benzoyl-7-propionyl-10-deacetyl-
10-O-(trimethylsilyl)-taxol (15) and 30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-2-
m-N3-benzoyl-7-propionyl-10-deacetyl-
taxol (5)
4.8. 20-O-(t-Butyldimethylsilyl)-30N-
debenzoyl-30N-isovaleryl-2-debenzoyl-2-
m-N3-benzoyl-10-deacetyl-10-O-
(trimethylsilyl)-taxol (14)
To a solution of 13 (387mg, 0.409 mmol) in
15.5ml THF were added bis(trimethylsilyl)
trifluoro-acetamide (0.543ml, 4.090 mmol)
and 1.0 M solution of LHMDS in THF
(0.041ml, 0.041 mmol) at 2208C under
nitrogen atmosphere and the mixture was
stirred for 10min at the same temperature.
The reaction was quenched with saturated
aqueous NH4Cl and extracted with EtOAc.
The combined organic layers were washed
with water and brine, dried over anhydrous
Na2SO4, filtered, and concentrated in vacuo.
The residue was purified by chromatog-
raphy on silica gel (petroleum ether:EtOAc
¼ 4:1) to afford 14 (344mg, 82.6% yield) as
a white solid. 1H NMR (300MHz, CDCl3) d
(a) To a solution of 14 (344 mg,
0.337 mmol), triethylamine (0.328ml,
2.359 mmol), and DMAP (4 mg,
0.034 mmol) in 7.0 ml THF was added
propionic anhydride (0.206 ml,
2.022 mmol) at 08C and the mixture
was stirred for 12h at room tempera-
ture. Then the reaction mixture was
diluted by EtOAc, washed by 2 M
aqueous HCl, aqueous NaHCO3, aqu-
eous NaCl and dried by anhydrous
Na2SO4. After filtration and removal of
EtOAc in vacuo, we obtained the
residue (359 mg). The residue was
subjected to silyl ether deprotection
without purification.

Journal of Asian Natural Products Research
471
(b) The above residue (359 mg) was
4.10. 20-O-(t-Butyldimethylsilyl)-7-O-
dissolved in 2.6 ml pyridine and
9.8 ml acetonitrile, and to this solution
40% aqueous HF (1.5ml) was added.
The reaction was stirred for 12h at
room temperature. The reaction was
quenched with saturated aqueous
NaHCO3 and the aqueous solution
wasextractedbyEtOAc.Thecombined
extracts were dried with anhydrous
Na2SO4 andconcentratedinvacuo. The
crude product was purified by column
chromatography on silica gel (pet-
roleum ether:EtOAc ¼ 1:1) to afford
5 (237mg, 79.1% yield for steps (a) and
(triethylsilyl)-cephalomannine (16)
To a solution of cephalomannine (5.157 g,
6.2 mmol) and imidazole (3.377 g,
49.6 mmol) in 51 ml DMF was added
TBSCl (6.540 g, 43.4 mmol) at room
temperature. After the mixture was stirred
for 4 h at 408C, TESCl (2.602 ml,
15.5 mmol) and imidazole (1.266 g,
18.6 mmol) were added. The mixture was
stirred for another 1 h at the same
temperature and diluted with EtOAc. The
solution was washed successively with
water and brine and concentrated in vacuo.
The residue was purified by chromatog-
raphy on silica gel (petroleum ether:E-
tOAc ¼ 5:1) to afford 16 (6.370 g, 96.9%
yield) as a white solid. 1H NMR (300 MHz,
CDCl3) d 8.12 (d, J ¼ 7.2 Hz, 2H), 7.59 (t,
J ¼ 7.2 Hz, 1H), 7.50 (t, J ¼ 7.2 Hz, 2H),
7.34 (t, J ¼ 7.5 Hz, 2H), 7.25–7.28 (3H,
m), 6.65 (d, J ¼ 8.7 Hz, 1H), 6.45 (s, 1H),
6.45 (overlapped, 1H), 6.25 (t, J ¼ 8.7 Hz,
1H), 5.70 (d, J ¼ 7.2 Hz, 1H), 5.58 (d,
J ¼ 9.0 Hz, 1H), 4.94 (d, J ¼ 9.0 Hz, 1H),
4.59 (d, J ¼ 1.8 Hz, 1H), 4.47 (dd,
J ¼ 10.8, 6.9 Hz, 1H), 4.30 (d,
J ¼ 8.4 Hz, 1H), 4.20 (d, J ¼ 8.4 Hz, 1H),
3.83 (d, J ¼ 7.2 Hz, 1H), 2.54 (s, 3H),
2.51–2.63 (m, 1H), 2.37 (dd, J ¼ 9.3,
12.3 Hz,1H), 2.17 (3H, s), 2.12 (dd,
J ¼ 8.8, 15.2 Hz,1H), 2.04 (s, 3H), 1.91
(m, 1H), 1.81 (s, 3H), 1.71 (d, J ¼ 7.2 Hz,
3H), 1.70 (s, 3H), 1.23 (s, 3H), 1.22 (s, 3H),
0.93 (t, J ¼ 8.1 Hz, 9H), 0.78 (s, 9H), 0.54–
0.61 (q, J ¼ 8.1 Hz, 6H), 20.05 (s, 3H),
20.33 (s, 3H); 13C NMR (100 MHz,
CDCl3) d 201.7, 171.4, 170.2, 169.3,
168.6, 167.1, 140.3, 138.5, 133.6, 131.5,
130.2, 129.2, 128.7, 128.6, 128.4, 127.7,
126.5, 126.4, 84.2, 81.1, 78.9, 77.3, 76.6,
75.0, 74.9, 72.2, 71.3, 58.4, 55.2, 46.6, 43.3,
37.2, 35.5, 26.6, 25.5, 23.1, 21.5, 20.8, 18.1,
14.2, 14.0, 12.3, 10.1, 6.7, 5.3, 25.3, 25.9;
ESI-MS: m/z 1060.6 [M þ H]þ; 1082.7
[M þ Na]þ.
20
(b)) as a white solid. ½aꢀD 255.3 (c
1
0.010, CH3OH); H NMR (500MHz,
CDCl3) d 7.88(d, J ¼ 7.5 Hz, 1H), 7.79
(s, 1H), 7.49 (t, J ¼ 7.5 Hz, 1H), 7.43–
7.30 (m, 5H), 7.24 (dd, J ¼ 7.5, 1.5 Hz,
1H), 6.28 (d, J ¼ 9.0 Hz, 1H), 6.14 (t,
J ¼ 8.5 Hz, 1H), 5.67 (d, J ¼ 7.0 Hz,
1H), 5.56 (dd, J ¼ 9.0, 2.0 Hz, 1H),
5.47 (dd, J ¼ 10.5, 7.5 Hz, 1H), 5.30 (s,
1H), 4.93 (d, J ¼ 8.5 Hz, 1H), 4.65 (dd,
J ¼ 5.0, 2.0 Hz, 1H), 4.33 (d,
J ¼ 8.5 Hz, 1H), 4.21 (d, J ¼ 8.5 Hz,
1H), 3.99 (d, J ¼ 7.0 Hz, 1H), 3.98 (s,
1H), 3.56 (d, J ¼ 5.0 Hz, 1H), 2.52
(ddd, J ¼ 14.5, 9.5, 7.5 Hz, 1H), 2.35–
2.29 (m, overlapped, 2H), 2.33 (s, 3H),
2.25 (q, J ¼ 7.5 Hz, 2H), 2.09–1.99
(m, 3H), 1.96–1.88 (m, 1H), 1.86 (s,
3H), 1.85 (s, 3H), 1.21 (s, 3H), 1.10(s,
3H), 1.09 (s, 3H), 1.09 (3H, J ¼ 7.5 Hz,
3H), 0.90 (d, J ¼ 5.0 Hz, 6H); 13C
NMR (125 MHz, CDCl3) d 210.8,
173.2, 172.7, 172.2, 170.2, 165.8,
140.8, 138.7, 138.2, 135.7, 130.9,
130.2, 128.9, 128.2, 127.0, 126.8,
124.4, 120.1, 83.8, 80.8, 78.6, 76.5,
75.1, 74.5, 73.0, 72.5, 71.4, 56.4, 54.5,
46.1, 45.9, 43.0, 35.9, 33.4, 27.6, 26.3,
26.2, 22.5, 22.4, 22.4, 20.5, 14.2, 10.9,
9.1; ESI-MS: m/z 889.1 [M þ H]þ;
911.4 [M þ Na]þ.

472
S.-E. Zhang et al.
4.11. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-7-O-(triethylsilyl)-
cephalomannine (17)
for 30 min at room temperature and 17
(3.667 g, 3.838 mmol) was added. Then
the reaction mixture was stirred for 72 h.
The reaction mixture was filtered and
washed by diethyl ether. The filtrate was
concentrated in vacuo and the residue was
purified by chromatography on silica gel
(petroleum ether:EtOAc ¼ 5:1) to afford
18 (3.491 g, 82.6% yield) as a white solid.
1H NMR (300 MHz, CDCl3) d 7.89 (d,
J ¼ 7.8 Hz, 1H), 7.80 (m, 1H), 7.48 (t,
J ¼ 7.8 Hz, 1H), 7.31–7.40 (m, 5H),
7.22–7.25 (m, 1H), 6.66 (d, J ¼ 8.7 Hz,
1H), 6.48 (s, 1H), 6.44 (q, overlapped, 1H),
6.20 (t, J ¼ 8.7 Hz, 1H), 5.70 (d,
J ¼ 7.2 Hz, 1H), 5.57 (dd, J ¼ 8.7,
1.5 Hz, 1H), 4.96 (d, J ¼ 8.1 Hz, 1H),
4.56 (d, J ¼ 1.5 Hz, 1H), 4.47 (dd,
J ¼ 10.5, 6.6 Hz, 1H), 4.32 (d,
J ¼ 8.4 Hz, 1H), 4.19 (d, J ¼ 8.4 Hz,
1H), 3.84 (d, J ¼ 7.2 Hz, 1H), 2.53 (s,
3H), 2.54–2.50 (m, overlapped, 1H),
2.40–2.34 (m, 1H), 2.18 (s, 3H), 2.22–
2.15 (m, 1H), 2.01 (s, 3H), 1.94–1.87 (m,
1H), 1.81 (s, 3H), 1.72 (d, J ¼ 7.2 Hz, 3H),
1.70 (s, 3H), 1.26 (s, 3H), 1.24 (s, 3H),
0.93 (t, J ¼ 7.8 Hz, 9H), 0.78 (s, 9H),
0.54–0.61 (q, J ¼ 7.8 Hz, 6H), 20.05 (s,
3H), 20.31 (s, 3H); 13C NMR (100 MHz)
d 201.7, 171.5, 170.1, 169.3, 168.7, 166.1,
140.7, 140.4, 138.6, 133.6, 131.5, 131.4,
131.0, 130.3, 128.6, 127.8, 126.8, 126.5,
124.3, 120.2, 84.3, 81.2, 78.8, 76.7, 75.4,
75.0, 74.9, 72.2, 71.5, 58.4, 55.2, 46.6,
43.3, 37.2, 35.5, 26.5, 25.5, 23.1, 21.5,
20.8, 18.1, 14.2, 14.0, 12.3, 10.1, 6.7, 5.3,
25.3, 25.9; ESI-MS: m/z 1101.7
[M þ H]þ; 1123.8 [M þ Na]þ.
To a solution of 16 (6.370 g, 6.009 mmol)
in 210 ml CH2Cl2 was added 40% solution
of Triton
B
in CH3OH (5.1 ml,
12.018 mmol) at 2308C and the solution
was stirred for 3 h. Then the reaction was
quenched by aqueous NH4Cl, and the
aqueous solution was extracted by
CH2Cl2. The combined extracts were
dried with anhydrous Na2SO4 and con-
centrated in vacuo. The residue was
purified by chromatography on silica gel
(petroleum ether:EtOAc ¼ 2:1) to afford
17 (3.667 g, 63.9% yield) as a white solid.
1H NMR (300 MHz, CDCl3) d 7.18–7.30
(5H, m), 6.65 (d, J ¼ 9.0 Hz, 1H), 6.48 (q,
J ¼ 7.8 Hz, 1H), 6.31 (s, 1H), 6.25 (t,
J ¼ 9.0 Hz, 1H), 5.49 (d, J ¼ 9.0 Hz, 1H),
4.47 (d, J ¼ 1.2 Hz, 1H), 4.34 (d,
J ¼ 11.4 Hz, 1H), 4.25 (t, J ¼ 9.3 Hz,
1H), 4.13 (dd, J ¼ 6.9 Hz, 1H), 3.88 (dd,
J ¼ 11.4, 3.9 Hz, 1H), 3.68 (d,
J ¼ 11.4 Hz, 1H), 3.26 (d, J ¼ 6.6 Hz,
1H), 2.64 (dd, J ¼ 14.7, 9.3 Hz, 1H), 2.38
(s, 3H), 2.20 (dd, J ¼ 14.7, 9.3 Hz, 1H),
1.91 (m, 2H), 1.90 (s, 3H), 1.88 (s, 3H),
1.78 (d, J ¼ 7.2 Hz, 3H), 1.28 (s, 3H), 1.11
(s, 3H), 0.93 (t, J ¼ 8.1 Hz, 9H), 0.78 (9H,
s), 0.56 (q, J ¼ 7.8 Hz, 6H), 20.07 (s, 3H),
20.04 (s, 3H); 13C NMR (126 MHz,
CDCl3) d 202.0, 171.9, 171.4, 169.3,
168.6, 139.7, 138.7, 136.4, 131.6, 131.5,
128.6, 127.8, 126.3, 95.2, 85.7, 76.6, 75.5,
75.1, 71.9, 71.3, 70.9, 70.5, 55.5, 55.2,
50.6, 43.5, 36.2, 35.1, 25.5, 25.2, 23.0,
21.7, 20.8, 18.1, 15.9, 14. 5, 14.1, 12.4,
6.8, 5.0, 25.2, 25.9; ESI-MS: m/z 956.6
[M þ H]þ; 978.7 [M þ Na]þ.
4.13. 2-Debenzoyl-2-m-N3-benzoyl-
cephalomannine (19)
4.12. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-2-m-N3-benzoyl-7-O-
(triethylsilyl)-cephalomannine (18)
To a solution of 18 (3.491 g, 3.170 mmol)
in 80.4 ml pyridine and acetonitrile was
added dropwise 40% solution of HF in
water (46.8 ml) at 08C. The mixture was
stirred at room temperature for 12 h.
The reaction was quenched with saturated
aqueous NaHCO3 and the aqueous
3-Azidobenzoic acid (4.564 g, 28 mmol),
DCC (5.974 g, 29 mmol), and DMAP
(0.122 g, 1 mmol) were dissolved in
60 ml toluene. The mixture was stirred

Journal of Asian Natural Products Research
473
solution was extracted by EtOAc. The
combined extracts were dried with anhy-
drous Na2SO4 and concentrated in vacuo.
The crude product was purified by column
chromatography on silica gel (petroleum
ether:EtOAc ¼ 1:1) to afford 19 (2.449 g,
J ¼ 7.8 Hz, 1H), 7.40–7.29 (m, 5H),
7.21–7.25 (m, 1H), 6.67 (d, J ¼ 9.0 Hz,
1H), 6.43 (q, J ¼ 7.2 Hz, 1H), 6.30 (s, 1H),
6.22 (t, J ¼ 9.0 Hz, 1H), 5.69 (d,
J ¼ 7.2 Hz, 1H), 5.56 (d, J ¼ 9.0 Hz,
1H), 4.99 (d, J ¼ 8.4 Hz, 1H), 4.54 (d,
J ¼ 1.8 Hz, 1H), 4.43 (dd, J ¼ 10.2,
6.9 Hz, 1H), 4.33 (d, J ¼ 8.1 Hz, 1H),
4.20 (d, J ¼ 8.1 Hz, 1H), 3.83 (d,
J ¼ 7.2 Hz, 1H), 2.59–2.52 (m, 1H), 2.52
(s, 3H), 2.42–2.34 (m, 1H), 2.24 (s, 3H),
2.04–2.01 (m, 1H), 1.89–1.94 (m, 1H),
1.90 (s, 3H), 1.81 (s, 3H), 1.72 (d,
J ¼ 7.2 Hz, 3H), 1.68 (s, Me-19, 3H),
1.28 (s, 3H), 1.15 (s, 3H), 0.80 (s, 9H),
20.08 (s, 3H), 20.33 (s, 3H); 13C NMR
(100 MHz) d 203.7, 171.4, 171.2, 170.0,
168.5, 166.0, 142.6, 140.7, 138.5, 132.8,
131.5, 130.9, 130.3, 128.7, 128.6, 127.8,
126.8, 126.4, 124.3, 120.1, 84.4, 81.1,
79.0, 76.4, 75.5, 75.4, 75.1, 72.0, 71.5,
58.5, 55.2, 45.4, 43.2, 35.7, 35.5, 33.9,
26.7, 25.5, 24.9, 23.0, 22.2, 20.8, 18.1,
14.9, 14.0, 12.3, 9.6, 25.4, 25.8; ESI-
MS: m/z 987.6 [M þ H]þ; 1009.6
[M þ Na]þ.
1
88.5% yield) as a white solid. H NMR
(300 MHz, CDCl3) d 7.89 (d, J ¼ 7.8 Hz,
1H), 7.80 (m, 1H), 7.48 (t, J ¼ 7.8 Hz,
1H), 7.31–7.40 (5m, H), 7.22–7.25 (m,
1H), 6.46 (d, J ¼ 8.7 Hz, 1H), 6.42 (q,
overlapped, 1H), 6.27 (s, 1H), 6.17 (t,
J ¼ 8.7 Hz, 1H), 5.65 (d, J ¼ 6.9 Hz, 1H),
5.58 (dd, J ¼ 2.7, 8.7 Hz, 1H), 4.94 (d,
J ¼ 8.1 Hz, 1H), 4.68 (s, 1H), 4.39 (dd,
J ¼ 10.8, 6.6 Hz, 1H), 4.30 (d, J ¼ 8.4 Hz,
1 Hz), 4.16 (d, J ¼ 8.4 Hz, 1H), 3.79 (d,
J ¼ 6.9 Hz, 1H), 2.54–2.49 (m, 1H), 2.32
(s, 3H), 2.30–2.23 (m, 1H), 2.24 (s, 3H),
2.08–2.01 (m, 1H), 1.82–1.92 (m, 1H),
1.80 (s, 6H), 1.72 (d, J ¼ 6.9 Hz, 3H), 1.67
(s, 3H), 1.25 (s, 3H), 1.14 (s, 3H); 13C
NMR (100 MHz) d 203.6, 172.8, 171.2,
170.3, 169.1, 165.9, 142.2, 140.7, 138.2,
133.0, 131.8, 131.2, 130.9, 130.2, 128.9,
128.2, 127.0, 126.8, 124.3, 120.2, 84.4,
81.0, 78.9, 76.4, 75.5, 75.4, 73.1, 72.3,
72.1, 58.5, 54.9, 45.5, 43.1, 35.6, 35.5,
26.8, 22.6, 21.8, 20.8, 14.8, 14.0, 12.4, 9.5;
ESI-MS: m/z 873.5 [M þ H]þ; 895.5
[M þ Na]þ.
4.15. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-2-m-N3-benzoyl-10-deacetyl-
cephalomannine (21)
To a solution of 20 (2.520 g, 2.553 mmol)
in ethanol was added dropwise 85%
hydrazine hydrate (4.978 ml, 88 mmol) at
08C and the mixture was stirred for 12 h at
the same temperature. The reaction was
quenched with saturated aqueous NH4Cl
and extracted with EtOAc. The combined
organic layers were washed with water and
brine, dried over anhydrous Na2SO4,
filtered, and concentrated in vacuo. The
residue was purified by chromatography
on silica gel (petroleum ether:EtOAc
¼ 2:1) to afford 21 (2.150 g, 89.1% yield)
as a white solid. 1H NMR (300 MHz,
CDCl3) d 7.92 (d, J ¼ 7.8 Hz, 1H), 7.82
(m, 1H), 7.51 (t, J ¼ 7.8 Hz, 1H), 7.38–
7.28 (m, 5H), 7.22–7.25 (m, 1H), 6.67 (d,
J ¼ 9.0 Hz, 1H), 6.41 (q, J ¼ 6.9 Hz, 1H),
4.14. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-2-m-N3-benzoyl-cephalo-
mannine (20)
To a solution of 19 (2.449 g, 2.806 mmol)
and imidazole in 25 ml DMF was added
TBSCl (2.537 g, 16.836 mmol) at room
temperature. The mixture was stirred for
4 h at 408C and then diluted with EtOAc.
The reaction mixture was then washed
with water and brine, dried over Na2SO4,
and concentrated in vacuo. The residue
was purified by chromatography on silica
gel (petroleum ether:EtOAc ¼ 3:1) to
afford 20 (2.520 g, 91.0% yield) as a white
1
solid. H NMR (300 MHz, CDCl3) d 7.92
(d, J ¼ 7.8 Hz, 1H), 7.83 (m, 1H), 7.51 (t,

474
S.-E. Zhang et al.
6.24 (t, J ¼ 8.7 Hz, 1H), 5.70 (d,
J ¼ 7.2 Hz, 1H), 5.54 (d, J ¼ 9.0 Hz,
1H), 5.20 (s, 1H), 4.98 (d, J ¼ 8.4 Hz,
1H), 4.54 (s, 1H), 4.35 (d, J ¼ 8.4 Hz, 1H),
4.27 (dd, J ¼ 10.8, 6.6 Hz, 1H), 4.21 (d,
J ¼ 8.4 Hz, 1H), 3.95 (d, J ¼ 7.2 Hz, 1H),
2.57–2.65 (m, 1H), 2.53 (s, 3H), 2.39–
2.32 (m, 1H), 2.19–2.12 (m, 1H), 1.83–
1.90 (m, 1H), 1.93 (s, 3H), 1.81 (s, 3H),
1.76 (s, 3H), 1.72 (d, J ¼ 6.9 Hz, 3H), 1.25
(s, 3H), 1.13 (s, 3H). 0.80 (s, 9H), 20.05
(s, 3H), 20.31 (s, 3H); 13C NMR
(100 MHz) d 211.4, 171.3, 170.1, 168.7,
166.0, 140.8, 138.8, 138.6, 135.6, 131.6,
131.4, 131.0, 130.3, 128.6, 127.8, 126.8,
126.5, 124.3, 120.1, 84.2, 81.1, 78.8, 76.5,
75.4, 75.0, 74.4, 71.8, 71.5, 57.7, 55.2,
46.2, 43.1, 36.9, 35.9, 26.3, 25.5, 23.0,
21.0, 18.1, 14.3, 14.0, 12.3, 9.9, 25.3,
25.9; ESI-MS: m/z 945.5 [M þ H]þ;
967.5 [M þ Na]þ.
(d, J ¼ 8.4 Hz, 1H), 3.83 (d, J ¼ 7.2 Hz,
1H), 2.65–2.57 (m, 1H), 2.55 (s, 3H),
2.57–2.47 (q, overlapped, 2H), 2.38 (m,
1H), 2.24 (m, 1H), 1.83–1.90 (m, 1H),
1.89 (s, 3H), 1.80 (s, 3H), 1.72 (d,
J ¼ 6.9 Hz, 3H), 1.68 (3H, s), 1.19 (t,
J ¼ 4.5 Hz, 3H), 1.16 (s, 3H), 1.14 (s, 3H),
0.79 (s, 9H), 20.08 (s, 3H), 20.32 (s, 3H);
13C NMR (75 MHz, CDCl3) d 203.8,
174.6, 171.5, 170.0, 168.7, 165.9, 142.5,
140.7, 138.4, 132.9, 131.6, 131.4, 130.9,
130.3, 128.6, 127.9, 126.8, 126.4, 124.4,
120.1, 84.5, 81.1, 79.0, 76.4, 75.5, 75.3,
75.0, 72.1, 71.6, 58.4, 55.2, 45.4, 43.2,
35.7, 35.5, 27.5, 26.7, 25.5, 23.0, 22.3,
18.1, 14.9, 14.0, 12.3, 9.6, 9.0, 25.4,
25.8; ESI-MS: m/z 1001.5 [M þ H]þ;
1024.5 [M þ Na]þ.
4.17. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-2-m-N3-benzoyl-7-epi-10-
deacetyl-10-propionyl-cephalomannine
(23)
4.16. 20-O-(t-Butyldimethylsilyl)-2-
debenzoyl-2-m-N3-benzoyl-10-deacetyl-
10-propionyl-cephalo-manine (22)
To a solution of 22 (703 mg, 0.701 mmol)
in 14.0 ml toluene was added 1,8-diazabi-
To a solution of 21 (972 mg, 1.028 mmol)
and propionic anhydride (0.795 ml,
6.168 mmol) in 24.3 ml THF was added
CeCl3 (25 mg, 0.103 mmol) and the
mixture was stirred for 12 h at room
temperature. The reaction mixture was
diluted with EtOAc, washed by saturated
aqueous Na2CO3 and brine, dried by
anhydrous Na2SO4, and concentrated in
vacuo. The residue was purified by
chromatography on silica gel (petroleum
ether:EtOAc ¼ 3:1) to afford 22 (950 mg,
cyclo[5.4.0]undec-7-ene
(2.121 ml,
14.2 mmol) and the mixture was stirred
for 2.5 h at 08C. The reaction mixture was
diluted by EtOAc, washed by 2 M aqueous
HCl and brine, dried by anhydrous
Na2SO4, and concentrated in vacuo. The
residue was purified by chromatography
on silica gel (petroleum ether:EtOAc
¼ 5:1) to afford 23 (446 mg, 63.5% yield)
as a white solid. 1H NMR (300 MHz,
CDCl3) d 7.96 (d, J ¼ 7.8 Hz, 1H), 7.84
(m, 1H), 7.52 (t, J ¼ 7.8 Hz, 1H), 7.43–
7.23 (m, 5H), 7.22–7.24 (m, 1H), 6.84 (s,
1H), 6.68 (d, J ¼ 9.0 Hz, 1H), 6.40 (q,
J ¼ 6.9 Hz, 1H), 6.22 (t, J ¼ 8.7 Hz, 1H),
5.77 (d, J ¼ 7.5 Hz, 1H), 5.61 (d,
J ¼ 9.0 Hz, 1H), 4.96 (dd, J ¼ 8.7,
3.6 Hz, 1H), 4.69 (d, J ¼ 11.7 Hz, 1H),
4.55 (d, J ¼ 1.8 Hz, 1H), 4.43 (s, 2H), 3.94
(d, J ¼ 7.5 Hz, 1H), 3.72 (d, J ¼ 11.5 Hz,
1H), 2.59 (s, 3H), 2.51 (q, J ¼ 7.5 Hz, 2H),
2.48–2.28 (m, 2H), 2.28–2.17 (m, 2H),
1.88 (s, 3H), 1.79 (s, 3H), 1.72
1
92.3% yield) as a white solid. H NMR
(300 MHz, CDCl3) d 7.91 (d, J ¼ 7.8 Hz,
1H), 7.82 (m, 1H), 7.50 (t, J ¼ 7.8 Hz,
1H), 7.42–7.27 (m, 5H), 7.22 (m, 1H),
6.67 (d, J ¼ 9.0 Hz, 1H), 6.42 (q,
J ¼ 6.9 Hz, 1H), 6.30 (1H, s), 6.20 (t,
J ¼ 8.7 Hz, 1H), 5.69 (d, J ¼ 7.2 Hz, 1H),
5.56 (d, J ¼ 9.0 Hz, 1H), 4.99 (d,
J ¼ 8.7 Hz, 1H), 4.54 (d, J ¼ 1.8 Hz,
1H), 4.44 (dd, J ¼ 10.8, 6.6 Hz, 1H),
4.34 (d, J ¼ 8.4 Hz, 1H), 4.20

Journal of Asian Natural Products Research
475
(d, J ¼ 6.9 Hz, 3H), 1.67 (s, 3H), 1.25–
1.20 (t, J ¼ 7.5 Hz, 3H), 1.22 (s, 3H), 1.16
(s, 3H), 0.79 (s, 9H), 20.07 (s, 3H), 20.31
(s, 3H); 13C NMR (75 MHz, CDCl3) d
207.3, 172.7, 172.0, 171.2, 168.8, 166.0,
140.7, 140.1, 138.4, 133.1, 131.5, 131.4,
131.0, 130.3, 128.6, 127.8, 126.8, 126.4,
124.2, 120.1, 82.7, 82.2, 79.0, 77.9, 77.5,
75.8, 75.7, 75.1, 71.2, 57.5, 55.1, 42.7,
40.2, 36.1, 35.3, 27.5, 25.8, 25.4, 22.8,
21.5, 18.1, 16.3, 14.8, 14.0, 12.3, 9.1,
25.4, 25.9; ESI-MS: m/z 1001.5
[M þ H]þ; 1024.5 [M þ Na]þ.
172.6, 172.2, 169.0, 166.1, 140.7, 139.8,
138.2, 133.2, 131.7, 131.3, 131.0, 130.2,
128.9, 128.1, 126.9, 126.8, 124.2, 120.1,
82.7, 82.0, 79.0, 77.9, 77.4, 75.7, 75.6, 73.1,
72.0, 57.5, 54.8, 42.6, 40.2, 36.0, 35.2, 27.5,
25.9, 22.5, 21.3, 16.1, 14. 7, 13.9, 12.4, 9.1;
ESI-MS: m/z 887.4 [M þ H]þ.
References
[1] A. Jemal, E. Ward, Y. Hao, and M. Thun,
J. Am. Med. Assoc. 294, 1255 (2005).
[2] A. Jemal, R. Siegel, E. Ward, T. Murray,
J. Xu, C. Smigal, and M.J. Thun,
CasCancer J. Clin. 56, 106 (2006).
[3] Y. Liu, T.C. Boge, S. Victory, S.M. Ali,
J. Zygmunt, G.I. Georg, R.T. Marquesz,
and R.H. Himes, Comb. Chem. High
Throughput Screen. 5, 39 (2002).
4.18. 2-Debenzoyl-2-m-N3-benzoyl-7-
epi-10-deacetyl-10-propionyl-
cephalomannine (6)
To a solution of 23 (696 mg, 0.695 mmol)
in 5.0 ml pyridine and 17.4 ml acetonitrile
was added dropwise 40% solution of HF in
water (2.7 ml) at 08C. The mixture was
stirred at room temperature for 12 h. The
reaction was quenched with saturated
aqueous NaHCO3 and the aqueous solution
was extracted by EtOAc. The combined
extracts were dried with anhydrous Na2SO4
and concentrated in vacuo. The crude
product was purified by column chroma-
tography on silica gel (petroleum ether:E-
tOAc ¼ 3:1) to afford 6 (510 mg, 82.7%
0.009, CH3OH); 1H NMR (300 MHz,
CDCl3) d 7.93 (d, J ¼ 7.5 Hz, 1H), 7.82
(m, 1H), 7.51 (t, J ¼ 7.8 Hz, 1H), 7.40–
7.32 (m, 5H), 7.27–7.23 (m, 1H), 6.81 (s,
1H), 6.55 (d, J ¼ 9.0 Hz, 1H), 6.38 (q,
J ¼ 6.9 Hz, 1H), 6.17 (t, J ¼ 8.4 Hz, 1H),
5.74 (d, J ¼ 7.5 Hz, 1H), 5.59 (dd, J ¼ 9.0,
2.4 Hz, 1H), 4.90 (dd, J ¼ 3.3, 8.4 Hz, 1H),
4.70 (d, J ¼ 2.4 Hz, 1H), 4.65 (d,
J ¼ 11.6 Hz, 1H), 4.36 (s, 2H), 3.91 (d,
J ¼ 7.5 Hz, 1H), 3.74 (d, J ¼ 5.1 Hz, 1H),
3.68 (dd, J ¼ 11.7, 3.0 Hz, 1H), 2.52 (q,
J ¼ 8.4 Hz, 2H), 2.45 (s, 3H), 2.27–2.35
(m, 4H), 1.77 (s, 6H), 2.12 (s, 6H), 1.70 (d,
J ¼ 6.9 Hz, 3H), 1.65 (s, 3H), 1.22 (t,
J ¼ 8.4 Hz, 3H), 1.20 (s, 3H), 1.15 (s, 3H);
13C NMR (75 MHz, CDCl3) d 207.2, 172.7,
[4] G.I. Georg, T.T. Chen, I. Ojima,
D.M. Vyas, Taxane Anticancer Agents:
Basic Science and Current Status (Amer-
ican Chemical Society, Washington, DC,
1995), p. 31.
[5] E.K. Rowinsky, Ann. Rev. Med. 48, 353
(1997).
[6] P.B. Schiff, J. Fant, and S.B. Horwitz,
Nature 277, 665 (1979).
[7] C.G. Yang, I. Barasoain, X. Li,
R. Matesanz, R.H. Liu, F.J. Sharom,
D.L. Yin, J.F. Diaz, and W.S. Fang,
Chem. Med. Chem. 2, 691 (2007).
[8] H.B. Wang, H.Y. Li, M.X. Zuo, Y. Zhang,
H. Liu, W.S. Fang, and X.G. Chen,
Cancer Lett 268, 89 (2008).
[9] N.C. Gwendolyn, D.H. Bruce, B. Susan,
A.L. Sally, M.W. Keith, and A.B. John,
J. Nat. Prod. 55, 414 (1992).
[10] I. Ojima, J. Chen, L. Sun, C.P. Borella,
T. Wang, M.L. Miller, S.N. Lin,
X.D. Geng, L. Kuznetsova, C.X. Qu,
D. Gallager, X.R. Zhao, I. Zanardi,
S.J. Xia, S.B. Horwitz, J.M. Clair,
J.L. Guerriero, D.B. Sagi, J.M. Veith,
P. Pera, and R.J. Bernacki, J. Med. Chem.
51, 3203 (2008).
[11] D.G. Kingston, A.G. Chaudhary,
M.D. Chordia, M. Gharpure, A.A. Guna-
tilaka, P.I. Higgs, J.M. Rimoldi,
L. Samala, and P.G. Jagtap, J. Med.
Chem. 41, 3715 (1998).
20
yield) as a white solid. ½aꢀD 2 23.2 (c
[12] A.G. Chaudhary, J.M. Rimoldi, and
D.G. Kingston, J. Org. Chem. 58, 3798
(1993).
[13] W.S. Fang, Q.C. Fang, and X.T. Liang,
Synth. Commun. 27, 2305 (1997).

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