Synthesis and radiolabelling of Re(CO)3-β-elemene derivatives as potential therapeutic radiopharmaceuticals

Article abstract of DOI:10.1002/jlcr.1580

β-Elemene, (1S, 2S, 4R)-(-)-(1-methy-1-vinyl-2,4-diisopropenyl cyclohexane) is an anticancer agent from the Traditional Chinese Herb Medicinal. Three novel Re(CO)₃-β-elemene derivatives including their radioactive conjugates containing N,N,N tridentate ligands and tricarbonyl rhenium (complex 12, 13, 14) were synthesized. Their structures were characterized by infrared (IR), ¹H-NMR and HRMS. Good radioactive yield (above 90%) and radioactive chemical purity with Re-188 (above 95%) were obtained for all of the three derivatives (complex 15, 16, 17). The antiproliferative activity of non-radioactive β-elemene-Re(CO)₃ derivatives on Lewis lung cancer cells and HeLa cell lines were evaluated by WST-1 methods. The result shows substantial decrease in IC₅₀ values compared with the parent compound β-elemene. The synthesis and radiosynthesis of β-elemene tricarbonyl rhenium conjugates provide the possibility to find a new kind of potential radiopharmaceuticals on β-elemene. Copyright

Full text of DOI:10.1002/jlcr.1580

Research Article
Received 7 January 2008,
Revised 22 November 2008,
Accepted 13 December 2008
Published online 20 January 2009 in Wiley Interscience
(
www.interscience.wiley.com) DOI: 10.1002/jlcr.1580
Synthesis and radiolabelling of Re(CO) -b-
3
elemene derivatives as potential therapeutic
radiopharmaceuticals
a,b
Yunfeng Ren, Yanhong Sun, Kangmin Cheng, Guifeng Liu,
and Yumei Shen
a
a,b
a,b
a
Ã
b-Elemene, (1S, 2S, 4R)-(ꢀ)-(1-methy-1-vinyl-2,4-diisopropenyl cyclohexane) is an anticancer agent from the Traditional
Chinese Herb Medicinal. Three novel Re(CO) -b-elemene derivatives including their radioactive conjugates containing N,N,N
tridentate ligands and tricarbonyl rhenium (complex 12, 13, 14) were synthesized. Their structures were characterized by
3
1
infrared (IR), H-NMR and HRMS. Good radioactive yield (above 90%) and radioactive chemical purity with Re-188 (above
95%) were obtained for all of the three derivatives (complex 15, 16, 17). The antiproliferative activity of non-radioactive
b-elemene-Re(CO) derivatives on Lewis lung cancer cells and HeLa cell lines were evaluated by WST-1 methods. The result
3
shows substantial decrease in IC50 values compared with the parent compound b-elemene. The synthesis and
radiosynthesis of b-elemene tricarbonyl rhenium conjugates provide the possibility to find a new kind of potential
radiopharmaceuticals on b-elemene.
Keywords: b-elemene; tricarbonyl rhenium; Re-188; antiproliferative activity; IC50
Introduction
b-elemene chlorinated intermediate as the main product. The
compound 2 was prepared similar to that of the reported
b-Elemene (Figure 1), (1S, 2S, 4R) 1-methy-1-vinyl-2,4-diisopro- procedure.6
penyl cyclohexane, a natural sesquiterpene extracted from the
1
Traditional Chinese Herb Medicinal Curcuma wenyujin and is the
main effective monomer of elemene emulsion. b-Elemene published synthetic strategy for the preparation of tridentate
exhibits anticancer effects in human and murine tumor cells in chelating systems with spacer groups comprising a terminal,
Synthesis of various chelating systems with the spacer entities
are presented in Schemes 2 and 3. We followed the recently
7
vitro and in vivo and has substantial clinical activity against
–4
primary amine functionality. Chelators with spacer entities were
various tumors without severe side effects. No bone marrow prepared as follows: for the synthesis of chelator 5, mono-Boc-
suppression and drug resistance have been observed in the protected diaminohexane 3 was treated with 2 equiv of
2
clinical studies; on the contrary, patient immunity was improved
during the therapy with b-elemene.
The nuclear properties of Re [T1/2 16.9 h; 2.12 MeV (71.6%) intermediate followed by Boc-deprotection with 6 N HCl
pyridine-2-carboxaldehyde and a slight excess of sodium
triacetoxy borohydride for in situ reduction of the imine
1
88
and 1.96 MeV (25.1%) b emissions, 155 KeV [(15%) g emissions]
would make it an ideal therapeutic radioisotopes. In this paper,
we synthesized three novel Re(CO)3-b-elemene derivatives protected 2, 2 -(ethylenedioxyl)diethylamine 6 (Scheme 3).
(
Scheme 2). Compound
8 was synthesized with similar
procedure to that of compound 5 starting from mono-Boc-
0
including their radioactive conjugates containing N,N,N triden-
tate ligands and tricarbonyl rhenium (complex 12, 13, 14); The
These intermediates including commercial available com-
pound di-(2-picoyl)-amine were coupled to the b-elemene
antiproliferative activity and structure characterization of non- chlorinated compound 1 under basic conditions to form the
radioactive b-elemene-Re(CO)3 derivatives were described; The corresponding intermediates 9, 10, 11 in very good yields.
radioactive yield and radioactive chemical purity with Re-188
were obtained for all of the three derivatives (complex 15, 16,
17). It is an attempt to radiolabelling b-elemene derivatives for
potential therapeutic radiopharmaceuticals.
a
Research Center of Radiopharmaceuticals, Shanghai Institute of Applied
Physics, Chinese Academy of Sciences, 2019 BaoJia Road, Shanghai 201800,
China
b
Results and discussion
Graduate School of the Chinese Academy of Sciences, 19 YuQuan Road, Beijing
00049, China
1
The synthesis procedure for the important intermediates was
shown in Scheme 1, the compound 1 was prepared according
5
to the literature with slight modification and careful control of
*
Correspondence to: Yumei Shen. Research Center of Radiopharmaceuticals,
Shanghai Institute of Applied Physics, Chinese Academy of Sciences, 2019 BaoJia
Road, Shanghai 201800, China.
reaction conditions in order to yield the 13-monosubstituted E-mail: shenyumei@sinap.ac.cn
J. Label Compd. Radiopharm 2009, 52 139–145
Copyright r 2009 John Wiley & Sons, Ltd.

Y. Ren et al.
The complex of [N(CH CH ) ] [ReBr (CO) ](2) was prepared
6
The rhenium complexes with oxidation states1V/1III have a
according to a previously published procedure. This complex higher tendency to reoxidized. Therefore, kinetically more inert
2
3 4 2
3
3
,8
is an important starting material for compounds containing the complexes containing rhenium in the low oxidation state1I have
9
–11
188
1
fac-Re(CO)3 moiety since the three bromide ligands are very received more attention, recently
weakly bound. When the[N(CH CH [ReBr (CO) ] complex was be an ideal candidate agent for labelling biomolecules. The
dissolved in water, the three bromide ligands were quantita- kinetic inertness of the Re(1I) oxidation state opens a new way
fac-[ Re(CO) (H O) ] may
3 2 3
2
3
)
4
]
2
3
3
1
88
tively exchanged by three H O molecules to form the complex for exploring the more oxidation sensitive Re for therapy.
2
1
of fac-[Re(CO)
even when exposed to air for weeks.
These substrates (9, 10, 11) are easy to coordinate and the method is according to the published procedure.
3
(H
2
O)
3
] , which is stable in aqueous solution
Radiosynthesis of compounds 15, 16, 17 was performed at
1
88
1
3 2 3
701C for 50 min with fac-[ Re(CO) (H O) ] as starting material
1
2–14
1
88
1
with [N(CH CH ) ] [ReBr (CO) ] to afford the non-radioactive The complex of fac-[ Re(CO) (H O) ] was synthesized with an
3
2
3 4 2
3
3
2
3
compounds 12, 13, 14 (Scheme 4). All the compounds were overall radiochemical yield of 92%, and with a radiochemical
1
characterized by infrared (IR), H-NMR, HRMS, HPLC or elemental purity of over 95% after a Sep-Pak silica cartridge separation.
s
analysis.
The ligand concentrations in the reactions were in
0ꢀ6–10ꢀ4 M range. At these concentrations, labelling yields
1
1
90% in respect to fac-[ Re(OH
88
1
4
2
)
3
(CO)
3
]
and specific
1
5
activities of up to 200 GBq/mmol ligand (based on initial activity
188
7
0
6
8
9
ꢀ
of 18 GBq/mL ReO
The formation of the
monitored by RP-HPLC, and showed generally slightly shift to
longer retention time (for 15, R = 21.21 min; for 16, R = 21.13 min;
for 17, R = 21.19 min) compared with that of free precursor
Br (R = 3.46min) and b-elemene derivatives (for 12,
R = 21.17 min; for 13, R = 20.07 min; for 14, R = 20.18 min)
4
) could be achieved (Scheme 5).
5
1
188
Re tricarbonyl complexes was
1
11
1
2
2
4
3
1
4
13
f
f
f
1
88
Re(CO)
Figure 1. Chemical Structure of b-elemene.
3
f
f
f
f
(
Figure 2). Formation of small amount of by-product was
observed in all of the three cases. The radioactive chemical purity
of the compounds 15, 16, 17 were 495% after purified by HPLC.
Stability of the Re-188 complexes was evaluated. The HPLC
purified product showed no evidence of degradation in PBS or
human plasma over a period of 24h at 371C.
a
1
Cl
The antiproliferative effect of non-radioactive Re(CO) -b-elemene
derivatives in mice Lewis lung cancer cells (LLC) and human HeLa
15
cervix carcinoma cells were evaluated by WST-1 method. MTT,
WST-1 and XTT method could be used to detect the cell viability.
WST-1, the tetrazolium salt 2-(4-iodophenyl)-3-(4-nitrophenyl)-
3
b
Re(CO) Br
[N(CH
2
CH
)
3
4
]
2
[ReBr
3
(CO) ]
3
5
2
Scheme 1. Reagents and conditions: (a)NaClO, CH
CH OCH CH OCH CH OCH , 1201C.
3
COOH, CH
2
Cl
2 4
, 01C; (b)N(Et) Br,
3
2
2
2
2
3
5-(2,4-disulfophenyl)-2H-tetrazolium
(Beyotime),
can
form
O
d
c
NH2
NH2
O
N
H N
2
H
3
N
N
O
e
N
N
N
H N
2
O
N
N
H
5
4
Scheme 2. Reagents and conditions: (c) Boc
2
O, CHCl
3
, 01C; (d) pyridine-2-carboxaldehyde, C
2
H
4
Cl
2
, 2 h, rt; (CH
3
COO)
3
BHNa, rt; (e)HCl 6 N, rt,3 h.
O
g
f
O
NH2
O
NH2
O
N
H
O
H N
2
O
6
N
O
N
N
h
O
N
N
O
N
H N
O
2
O
N
H
2
8
7
Scheme 3. Reagents and conditions: (f) Boc
2 3 2 4 2 3 3
O, CHCl , 01C; (g) pyridine-2-carboxaldehyde, C H Cl , 2 h, rt; (CH COO) BHNa, rt; (h) HCl 6 N, rt, 3 h.
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Copyright r 2009 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2009, 52 139–145

Y. Ren et al.
CO
CO
CO
N
N
+
N
Re
N
H
!
p /!q
p /!q
!r
Br-
12
N
N
N
N
H
9
!
N
N
!r
Cl
1
N
-
CO
N
N
Br
Re
1
0
+
N
CO
CO
13
!p /!q
N
N
O
N
!
r
N
O
H
11
CO
CO
CO
N
+
N
Re
O
N
O
N
Br-
H
14
Scheme 4. Reagents and conditions: (i) NaOH, CH
3
CN, 631C, 8 h; (ii) 5 or di-(2-picolyl)amine or 8; and (iii) 2 in CH
3
OH, rt, 40 min.
+
+
CO
CO
N
N
188Re
CO
CO
N
188Re
CO
CO
N
N
H
N
16
N
1
5
-
4
-4
9
,10 ,50min,75!
10,10 ,50min,75!
H O
2
OH2
H O
2
188Re
OC
CO
CO
-4
1
1,10 ,50min,75!
+
CO
CO
CO
N
188Re
O
N
N
H
O
N
1
7
Scheme 5. Radiosynthesis of complex 15, 16, 17.
1
6
water-soluble tetrazolium salts after incubated with active cells but reported as P = 199.574.12. The oil–water partition coeffi-
1
88
1
3 2 3
not the MTT-formazan crystals. The results are shown in Table 1. cients of b-elemene- Re(CO) (H O) complexes was improved
Their antiproliferative activities of compound 12, 13 and 14 were more than 20 times than the parent b-elemene.
improved significantly in comparison to b-elemene ( po0.01).
Experimental
1
88
Octanol/water partition coefficient of b- elemene- Re(CO)
3
Materials and instruments
To evaluate the aqueous solubility of the complex, octanol/
water partition coefficient was determined. The results were b-elemene was obtained from WenTe Research Institute of
shown in Table 2. Compared with that of b-elemene, which was Oleum Curcumae Wenchowensis in Yue Qing city, Zhejinag
J. Label Compd. Radiopharm 2009, 52 139–145
Copyright r 2009 John Wiley & Sons, Ltd.
www.jlcr.org

Y. Ren et al.
188
3
Figure 2. HPLC analyses of the complex 12–14 and radioactive HPLC-traces of the Re(CO) -b-elemene radiotracers 15–17.
spectrometer. The chemical shifts as d are reported in ppm
relative to TMS. IR spectra were recorded on a Perkin-Elmer FT-IR
spectrometer. Mass spectral data were collected using positive
mode on a Finnigan LCQ classic mass spectrometer. Elemental
analysis was performed using a Perkin-Elmer Series III analyser.
Table 1. The antiproliferative activity of Re(CO) -b-ele-
mene derivatives in LLC and HeLa cell lines
3
IC50(mM)
Compounds
HeLa
LLC
b-elemene
236.273.2
10.971.2
11.271.5
10.572.9
346.1741.5
5.071.9
5.171.3
A general procedure for the formation of 13-chloro-b-
elemene (compound 1)
Compound 12
Compound 13
Compound 14
4.872.3
To a solution of b-elemene (2 g, 9.79 mmol) in ice acetic acid
(
2 mL), sodium hypochlorite (13.5 mL) was added over 4 h period
under stirring at ice cold, then the mixture was stirred for 2 h at
room temperature and extracted with EtOAc. The combined
organic extracts were washed with water, dried over anhydrous
MgSO and filtered. The filtrate was concentrated in vacuo to
4
yield the mixture as yellow oil (2 g, 60%), which was used for the
next step without further purification.
Table 2. Oil–water partition coefficient of 12-14
Complexes
P
Log P
Complex 12
Complex 13
Complex 14
11.5071.05
13.2071.05
9.4871.07
1.0670.02
1.1270.02
0.9870.03
2 3 4 2 3
The procedure for the formation of [N(CH CH ) ] [ReBr -
(CO) ] (compound 2)
3
4
Powdered N(Et) Br (158.2 mg) was stirred in 14 mL of 2,5,8-
province (purity 98%). Other materials were purchased trioxanonane (diglyme) under dry argon and heated to 801C.
from Fluka Co. and Sinopharm Chemical Reagent Co. Ltd. The Then solid [ReBr(CO) ] (118.2 mg) was added into the mixture
5
NMR data were obtained using a Bruker DRX 500 MHz FT and kept at 1201C for 8 h, during which a pale yellow precipitate
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Copyright r 2009 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2009, 52 139–145

Y. Ren et al.
formed. The mixture was filtered while hot and washed with and CH ), 2.68 (t, J = 6.96 Hz, 2H), 3.11 (q, J = 6.41 Hz, 2H), 4.59
2
ꢀ
1
several portions of cold diglyme, diethyl ether and dried at (s, 1H); IR (KBr) n: 3344, 2925, 1699, 1527, 1174 cm ; EI-HRMS:
001C in vacuum. The resulting pale yellow solid was then calcd for C11 216.1838, found 216.1808.
slurried in 3 mL absolute ethanol to remove unreacted NEt Br.
1
24 2 2
H N O
4
Filtration and drying in vacuum yielded the product as a pale Synthesis of compound 4
yellow powder (130 mg, 73%).
Pyridine-2-carboxaldehyde (3.1018 g; 28.9mmol; 2.1 equiv) dis-
1
General procedure for the formation of fac-[ Re(CO)
7
188
solved in 40mL of dry 1,2-dichloroethane was added to a solution
of compound 3 (2.8778 g; 13.3mmol; 1 equiv) in 50mL of dry 1, 2-
dichloroethane and stirred for 2 h at room temperature. The
3
1
(H O) ]
2 3
Powdered BH
(
3
ꢁ NH
3
(5.0 mg) was added into a 10 mL glass vial reaction solution was cooled to 01C before slow addition of
flushed with N
2
for 10 min firstly). The vial was capped with a sodium triacetoxy borohydride (6.1783 g; 29.1mmol; 2.3 equiv) in
rubber stopper and an aluminum seal and then filled with CO portions. After 24h of stirring at room temperature, water was
gas for 20 min. The radiolabelling procedure was performed by added to quench residual sodium triacetoxy borohydride and the
adding a mixture of 6 mL of phosphoric acid (85%) and 1 mL of reaction mixture extracted twice with CH Cl . The organic layer
2
2
1
88
ReO (18 GBq/mL) into the vial and incubating in a water bath was extracted with water and brine, dried over Na SO ,
4
2
4
at 70–801C for 15 min. A 10 mL syringe was used to keep the evaporated, and dried in a vacuum. A colorless oil, 75% yield;
1
balance of H
2
gas. The chelating efficiency was determined by
3
H NMR (CDCl , TMS, 500 MHz), d: 1.18–1.31 (m, 4H), 1.40–1.48
TLC, using a silica GF254 glass plate as stationary phase and (m, 11H), 1.50–1.56 (m, 2H), 2.53 (t, J = 7.20Hz, 2H), 3.07
CH
1
3
OH:HCl (36%) = 99:1 as mobile phase. In this system, colloidal (d, J = 6.22Hz, 2H), 3.81 (s, 4H), 4.75 (s, 1H), 7.14 (t, J = 5.75 Hz,
88
188
of [ Re(CO)
1
1
2H), 7.54 (d, J = 7.582 Hz, 2H), 7.66 (dt, J = 7.67 Hz, J = 1.71 Hz,
2
ReO
2
stays at the origin (R
1
f
= 0), the R
f
3
(H
2
O)
3
]
88
is 0.4–0.6, and the free Re perrhenate has an R of 0.8–1.0. The 2H), 8.52 (d, J = 4.77Hz, 2H); IR (KBr) n: 3368, 3061, 2931, 1709,
yield of the product is better than 92%, and with a radio- 1171, 760 cm ; EI-HRMS: calcd for C H N O 398.2682, found
chemical purity of over 95% after a Sep-Pak silica cartridge 398.2679.
separation.
f
ꢀ
1
2
3 34 4 2
s
Synthesis of compound 5
The Boc-deprotection of compound 4 (692 mg, 1.73 mmol;
The antiproliferative evaluation by WST-1 method
1
equiv) was achieved quantitatively in 6 N HCl (15mL) after 4 h
LLC and HeLa cells were maintained in DMEM with 10%
inactivated fetal bovine serum. The cell lines were grown in
logarithmic growth at 371C in a humidified atmosphere
at room temperature as determined by TLC/ninhydrin. After
addition of 10 N NaOH to obtain a pH value of 5, the reaction
mixture was evaporated and dried in a vacuum. Methanol was
added and the mixture was filtered to remove the precipitated salt
colorless oil, 92% yield; H NMR (CDCl3, TMS, 500 MHz),
d: 1.20–1.29 (m, 4H), 1.35–1.41 (m, 2H), 1.50–1.55 (m, 2H), 1.75
2
consisting of 5% CO and 95% air. The cells were harvested
3
using 0.25% trypsin-EDTA and seeded 5 ꢂ 10 cells in each well
1
of a 96-well plate and incubated for 12 h. Then the Re(CO) -b-
3
elemene derivatives and the parent compound b-elemene were
added to wells of the plate at concentrations (100, 10, 1 mmol/L)
(
(
2
s, 2H), 2.52 (t, J = 7.29, 2H), 2.62 (t, J = 7.06 Hz, 2H), 3.79 (s, 4H), 7.12
1
t, J = 5.20 Hz, 2H), 7.52 (d, J= 7.80 Hz, 2H), 7.63 (dt, J = 7.71Hz,
and continued to culture in CO
2
incubator for 24 h. Ten
J = 1.66 Hz, 2H), 8.50 (d, J= 4.13 Hz, 2H); IR (KBr) n: 2924, 2028,
microliter WST-1 solution was added to wells, absorbance
values were taken using a 96-well Opsys Microplate Reader at
-1
1917 cm ; EI-HRMS: calcd for C18
26 4
H N 298.2157, found 298.2157.
4
50 nm. IC50 were calculated according to absorbance.
Synthesis of compound 6
IC50 were calculated with SPSS 11.5 statistical software,
differences between mean values were analyzed with students’ Compound 6 was synthesized with similar procedure to that of
0
t-tests. Differences were considered significant when po0.01. compound 3 starting from 2,2 -(ethylenedioxyl)diethylamine.
1
A colorless oil, 92% yield; H NMR (CDCl
Data are presented as mean7SD.
3
, TMS, 500 MHz), d: 1.39
s, 9H), 2.31–2.49 (m, 2H), 2.84 (s, 2H), 3.27 (s, 2H), 3.47–3.57
(
ꢀ
1
;
Partition coefficient study
(m, 8H), 5.26 (s, 1H); IR (KBr) n: 584.3, 1708.9, 2972.9, 3342.6 cm
ESI-HRMS: calcd for C11 249.1814, found 249.1809.
25 2 4
H N O
Usually the final partition coefficient value was expressed as
1
log P. Log P of b-elemene - Re(CO)
88
3
was determined by
Synthesis of compound 7
measuring the distribution of radioactivity in 1-octanol and
1
88
PBS. A 5 mL sample of aˆ -elemene- Re(CO) in PBS was added to Compound 7 was synthesized with similar procedure to that of
3
1
a vial that contains 1 mL 1-octanol and 1 mL PBS. After vortexing compound 4. A colorless oil, 80% yield; H NMR (CDCl , TMS,
3
for 5 min, the vial was centrifuged for 5 min to ensure complete 500 MHz), d: 1.39 (s, 9H), 2.45 (s, 1H), 2.86 (t, J = 5.60 Hz, 2H),
separation of layers. Then, 5 mL of each layer was pipetted into 3.26–3.34 (m, 2H), 3.51–3.59 (m, 6H), 3.63 (t, J = 6.00 Hz, 2H), 3.93
other test tubes, and log P values were calculated using the (s, 4H), 7.15 (t, J = 5.60 Hz, 2H), 7.54 (d, J = 7.60 Hz, 2H), 7.65 (dt,
1
8
1
2
formula: Log P = Log (counts in octanol/counts in water).
J = 7.60 Hz, J = 1.60 Hz, 2H), 8.53 (d, J = 4.40 Hz, 2H); IR (KBr)
1
ꢀ
n: 1364, 1701, 2358, 2931, 3499 cm
; EI-MS: calcd for
Synthesis of compound 3
C H N O 430.3, found 430.4.
2
3 34 4 4
Compound 3 was synthesized according to a previously
Synthesis of compound 8
1
9
published procedure,
A colorless oil, 94% yield; H NMR (CDCl
d: 1.30–1.37 (m, 4H), 1.40–1.51 (m, 11H), 1.60–1.68 (m, 4H, NH
starting from 1,6-diaminohexane.
1
3
, TMS, 500 MHz), Compound 8 was synthesized with similar procedure to that of
1
2
compound 5. A colorless oil, 87% yield; H NMR (CDCl , TMS,
3
J. Label Compd. Radiopharm 2009, 52 139–145
Copyright r 2009 John Wiley & Sons, Ltd.
www.jlcr.org

Y. Ren et al.
5
00 MHz), d: 2.64 (s, 2H), 2.76–2.85 (m, 4H), 3.48–3.68 (m, 8H), Compound 12
.87 (s, 4H), 7.12 (t, J = 6.40 Hz, 2H), 7.51 (d, J = 7.60 Hz, 2H), 7.62
3
(
1
1
dt, J = 7.60 Hz, J = 1.60 Hz, 2H), 8.49 (d, J = 4.80 Hz, 2H); IR (KBr)
2
A white solid, 78% yield, m.p. 161.7–162.11C; H NMR (CDCl
TMS, 500 MHz), d: 0.99 (s, 3H), 1.23–1.33 (m, 2H), 1.38–1.46 (m,
H), 1.47–1.59 (m, 3H), 1.62–1.83 (m, 4H), 1.70 (s, 3H), 2.10–2.21
m, 4H), 2.27–2.33 (m, 1H), 3.05 (t, J = 7.16 Hz, 2H), 3.70 (q,
3
,
ꢀ
1
n: 1858, 1999, 2987, 3458 cm ; ESI-HRMS: calcd for C H N O
1
8 27 4 2
2
(
331.2134, found 331.2123.
J = 14.00 Hz, 2H), 3.81 (t, J = 8.08 Hz, 2H), 4.57 (s, 1H), 4.73 (d,
J = 16.75 Hz, 2H), 4.81 (s, 1H), 4.87–4.89 (m, 1H), 4.91 (s, 1H), 5.26
General procedure for the preparation of compounds 9–11
A solution of Cl-b-elemene, (2 mmol), 5 or di-(2-picolyl)amine or (s, 1H), 5.45 (s, 1H), 5.59 (d, J = 17.02 Hz, 2H), 5.82 (dd,
(4 mmol), and sodiun hydroxide (8 mmol) in 10 mL dry J = 17.49 Hz, 10.85, 1H), 7.23 (t, J = 6.71 Hz, 2H), 7.84 (dt,
acetonitrile was refluxed for 8–10 h. Then water (10 mL) was J = 7.74 Hz, 0.38, 2H), 7.93 (d, J = 7.81 Hz, 2H), 8.67 (d, J = 5.4 Hz,
8
ꢀ
1
added and the mixture was extracted with ethyl ether 2H). IR (KBr) n: 3472, 2926, 2027, 1912 cm ; anal. calcd for
(
4 ꢂ 30 mL). The comp-bined organic extracts were dried over
C
36
H
48BrN
4
O
3
Re ꢁ CH
2
Cl
2
: C 47.49, H 5.39, N 5.99; found C 47.29,
anhydrous sodium sulfate and filtered. The filtrate was H 5.64, N 6.26.
concentrated in vacuo. The residue was purified on a silica gel
column with dichloromethane-methanol as eluent to give a Compound 13
target product.
1
A white solid, 82 % yield; H-NMR (CDCl , TMS, 500 MHz), d: 1.03
3
(
2
s, 3H, CH
H), 1.97–2.02 (m, 1H), 2.17–2.19 (m, 1H), 2.30–2.39 (m, 1H),
A brown oil, 80% yield; H NMR (CDCl , TMS, 500 MHz), d: 0.97 (s, 4.36–4.49 (m, 4H), 4.61 (s, 1H), 4.85 (s, 1H), 4.91–4.99 (m, 2H),
3 3
), 1.51–1.58 (m, 3H), 1.68 (s, 3H, CH ), 1.72–1.82 (m,
Compound 9
1
3
3
(
H), 1.19–1.32 (m, 4H), 1.35–1.60 (m, 8H), 1.62–1.75 (m, 2H), 1.69 5.53 (s, 1H), 5.62 (s, 1H), 5.77–5.89 (q, 1H), 6.05 (q, J = 18.53 Hz,
s, 3H), 1.96–2.12 (m, 2H), 2.55 (t, J = 6.88 Hz, 2H), 2.89 (t, 2H), 7.18 (t, J = 6.39 Hz, 2H), 7.80 (t, J = 7.63 Hz, 2H), 8.00 (d,
J = 7.78 Hz, 2H), 3.61 (s, 2H), 3.84 (s, 4H), 4.55 (s, 1H), 4.80 (s, 1H), J = 7.64 Hz, 2H), 8.63 (d, J = 5.34 Hz, 2H); IR (KBr): 3080, 2027,
1
ꢀ1 13
4
.87–4.94 (m, 2H), 5.15 (s, 1H), 5.17 (s, 1H), 5.79 (dd, J = 17.71 Hz, 1910 cm ; C-NMR (CDCl
3
, TMS, 125 MHz), d: 17.23, 25.64,
J = 10.54 Hz, 1H), 7.17 (t, J = 5.6 Hz, 2H), 7.50 (d, J = 7.79 Hz, 2H), 28.00, 34.65, 40.44, 40.82, 44.52, 52.92, 67.78, 67.92, 74.48,
2
1
.67 (dt, J = 7.67 Hz, J = 1.64 Hz, 2H), 8.53 (d, J = 4.19 Hz, 2H); IR 110.86, 113.00, 121.66, 125.85, 126.36, 140.96, 147.12, 148.02,
2
7
ꢀ
1
(
KBr) n: 2928, 2362, 1388 cm ; ESI-HRMS calcd for C H N
150.49, 151.07, 161.84, 161.95, 196.22, 196.86; anal. calcd for
: C 46.99, H 4.73, N 7.31; found C 46.63,
3
3 49 4
5
01.3957, found 501.3922.
C
30
H
36BrN
H 4.69, N 7.08.
4
O
3
Re ꢁ CH
2
Cl
2
Compound 10
A brown oil, 87% yield; H-NMR (CDCl
Compound 14
1
3
, TMS, 500 MHz), d: 0.90 (s,
1
3H), 1.47–1.27 (m, 6H), 1.61 (s, 3H), 1.92–1.89 (m, 1H), 2.07–2.04 A white solid, 75 % yield; H NMR (CDCl , TMS, 500 MHz), d: 1.00
3
(
1
(
m, 1H), 3.06 (q, 2H, J = 14.0 Hz), 3.73 (q, J = 14.1Hz, 4H), 4.47 (s, (s, 3H), 1.38–1.47 (m, 2H), 1.48–1.61(m, 2H), 1.74 (s, 3H),
H), 4.73 (s, 1H), 4.84 (dd, J = 5.82 Hz, J = 1.08Hz, 1H), 4.85 1.65–1.93 (m, 10H), 2.08–2.31(m, 6H), 3.01–3.09 (m, 2H),
d, J = 1.3 Hz, 1H), 4.89 (s, 1H), 5.06 (s, 1H), 5.77 (dd, J = 10.48 Hz, 3.62–3.74 (m, 2H), 3.76–3.85 (m, 2H), 4.58 (s, 1H), 4.73 (d,
J = 7.38Hz, 1H), 7.09–7.07 (m, H), 7.50–7.47 (m, H), 7.60 (dt, J = 16.80 Hz, 2H), 4.81 (s, 1H), 4.87 (s, 1H), 4.91 (d, J = 8.8 Hz, 1H),
J = 7.65Hz, J = 1.57Hz, 2H), 8.45 (d, J = 4.3 Hz, 2H); IR (KBr): 3080, 5.27 (s, 1H), 5.48 (s, 1H), 5.64 (d, J = 16.80 Hz, 2H), 5.82 (dd,
ꢀ
1 13
1
3
1
1
640cm
;
3
C-NMR (CDCl , TMS, 125 MHz), d: 17.39, 25.31, 27.68, J = 17.49 Hz, 10.85, 1H), 7.23 (t, J = 6.80 Hz, 2H), 7.84 (t, J = 7.60 Hz,
3.73, 40.57, 40.74, 42.56, 53.74, 59.71, 60.80, 110.53, 111.63, 2H), 7.95 (d, J = 7.60 Hz, 2H), 8.68 (d, J = 6.80 Hz, 2H). IR (KBr) n:
ꢀ
1
12.71, 122.62, 123.41, 137.10, 148.14, 149.61, 150.94, 152.06, 1914, 2028, 2928, 3437 cm . Calcd for [C36
48 4 5
H N O Re]Br ꢁ 1/
60.46; ESI-HRMS calcd for C33 401.2831, found 401.2842. 3CH Cl : C 47.89, H 5.38, N 6.15; found C 47.80, H 5.45, N 6.11.
2
H N
49 4
2
Compound 11
A brown oil, 81% yield; H NMR (CDCl
3
3
Radiochemical synthesis of 15–17
1
3
, TMS, 500 MHz), d: 0.97 (s,
H), 1.35–1.63 (m, 6H), 1.67 (s, 3H), 1.97–2.16 (m, 2H), 2.89 (s, 2H),
.22 (t, J = 4.32 Hz, 2H), 3.46–3.51 (m, 2H), 3.57–3.65 (m, 4H), 3.69
Complexes 15–17 were prepared according to the following
17,20–22
188
1
general procedure:
1
7
3 2 3
fac-[ Re(CO) (H O) ] was added to
ꢀ4
00 mL 9 or 10 or 11(10 mol/L). The mixture was incubated at
01C for 50 min. HPLC analyses of the complexes 15–17
(
2
1
s, 2H), 3.81–3.95 (m, 6H), 4.54 (s, 1H), 4.80 (s, 1H), 4.86–4.94 (m,
1
2
H), 5.18 (s, 1H), 5.32 (s, 1H), 5.78 (dd, J = 17.85 Hz, J = 6.85 Hz,
H),7.17 (t, J = 6.65 Hz, 2H), 7.38 (d, J = 7.45 Hz, 2H), 7.66 (t,
revealed yields between 90 and 96%. Radioactive chemical
purity with Re-188 (above 95%) was obtained for all of the three
derivatives
J = 7.64 Hz, 2H), 8.55 (d, J = 3.97 Hz, 2H); IR (KBr) n: 765, 1591,
1
1
639, 2928, 3371 cmꢀ ; ESI-HRMS calcd for C H N O2
33 49 4
533.3856, found 533.3845.
Conclusion
General procedure for the preparation of compounds 12–14
Three novel b-elemene Re complexes have been prepared and
Complexes 12–14 were prepared according to the following characterized successfully. Their antiproliferative activity in vitro
general procedure: 2 mmol [N(CH CH [ReBr (CO) ], and on LLC and HeLa cell lines were increased significantly
mmol corresponding derivative (9, 10, 11) was dissolved in compared with that of the parent b-elemene by WST-1
2
3
)
4
]
2
3
3
2
CH OH and stirred for 30 min. The mixture was evaporated and methods. The radiolabelling of these three b-elemene Re free
3
188 1
dried in a vacuum and the production was recrystallized with derivatives with fac-[ Re(CO)
n-hexane: dichloromethane = 1:2
3
(H
2
O)
3
]
and efficient. Their further biological evaluation for radioactive
was straightforward
www.jlcr.org
Copyright r 2009 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2009, 52 139–145

Y. Ren et al.
target compounds in vivo is under way and will be reported in
due course.
[8] J. Y. Xia, Y. X. Wang, J. F. Yu, J. Radioanal. Nucl. Chem. 2005, 266,
313–316.
[9] M. Wenzel, M. J. Saidi, Labelled Compd. Radiopharm. 1993, 33,
7
7–80.
Acknowledgement
[
10] S. Top, P. Morel, M. Pankowski, G. Jaouen, J. Chem. Soc. Dalton
Trans. 1996, 12, 3611–3612.
This project was supported by Hundred Talent Program of [11] G. E. D. Mullen, P. J. Blowe et al., Inorg. Chem. 2000, 39,
4093–4098.
Chinese Academy of Sciences (No.26200601).
[
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