Synthesis of new carbon-11-labeled 7-aroylaminoindoline-1-sulfonamides as potential PET agents for imaging of tubulin polymerization in cancers

Article abstract of DOI:10.1002/jlcr.1462

The tubulin polymerization is an attractive target for anticancer therapy and in the development of cancer imaging agents for use in biomedical imaging technique positron emission tomography (PET). 7-Aroyl-aminoindoline-1 -sulfonamides are a novel class o

Full text of DOI:10.1002/jlcr.1462

Research Article
Received 12 July 2007,
Revised 21 August 2007,
Accepted 22 August 2007
Published online 3 January 2008 in Wiley Interscience
(www.interscience.wiley.com) DOI: 10.1002/jlcr.1462
Synthesis of new carbon-11-labeled 7-aroyl-
aminoindoline-1-sulfonamides as potential
PET agents for imaging of tubulin
polymerization in cancers
Min Wang,a Mingzhang Gao,a Kathy D. Miller,b George W. Sledge,b
Ã
Gary D. Hutchins,a and Qi-Huang Zhenga
The tubulin polymerization is an attractive target for anticancer therapy and in the development of cancer imaging agents
for use in biomedical imaging technique positron emission tomography (PET). 7-Aroyl-aminoindoline-1-sulfonamides are a
novel class of potent antitublin agents. Carbon-11-labeled 7-aroyl-aminoindoline-1-sulfonamides have been synthesized as
new potential PET agents for imaging of tubulin polymerization in cancers. The target tracers were prepared by O-
[
11C]methylation of their corresponding precursors using [11C]CH3OTf and isolated by a simplified solid-phase extraction
purification procedure in 40–55% radiochemical yields based on [11C]CO2 and decay corrected to the end of bombardment
(EOB), 15–20 min overall synthesis time from EOB, >98% radiochemical purity, and 74–111 GBq/lmol specific activity at the
end of synthesis.
Keywords: carbon-11; 7-aroyl-aminoindoline-1-sulfonamides; PET; tubulin polymerization; cancer imaging
polymerization inhibitor treatment using PET. To translate
chemotherapeutic agent for diagnostic use, we are interested
Introduction
Microtubules are one of the components of the cytoskeleton
and are composed of a- and b-tubulin dimers, which serve as
structural components within cells and are involved in many
cellular processes including mitosis, cytokinesis, and vesicular
transport.1 Tubulin dimers constantly polymerize and depoly-
merize, and microtubules can undergo rapid cycles of assembly
and disassembly.2 Microtubules are recognized as an important
target for anticancer therapy.3 Recently, a novel series of 7-aroyl-
aminoindoline-1-sulfonamides have been developed as
potent inhibitors of tubulin polymerization, and four title
compounds N-[1-(4-methoxy-benzenesulfonyl)-2,3-dihydro-1H-
indol-7-yl]-acetamide (4a), furan-2-carboxylic acid [1-(4-meth-
oxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-amide (4b), 4-fluoro-
N-[1-(4-methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-
benzamide (4c), and N-[1-(4-methoxy-benzenesulfonyl)-2,3-dihy-
dro-1H-indol-7-yl]-isonicotinamide (4d) are all potent antitubulin
agents with excellent biological activity, in which the lead
compound 4d inhibited the human cancer cell growth of KB,
MKN45, H460, HT29, and TSGH, and one human-resistant cancer
line of KB-vin 10 with nanomolar IC50 values (9.6, 8.8, 9.4, 8.6,
10.8, and 8.9 nM, respectively).4 Tubulin polymerization and
depolymerization also provide an attractive target for the in vivo
biomedical imaging technique positron emission tomography
(PET) to image cancers. 7-Aroyl-aminoindoline-1-sulfonamides
labeled with a positron-emitting radionuclide such as carbon-11
may enable non-invasive monitoring of cancer tubulin poly-
merization and depolymerization and their response to tubulin
in the design and synthesis of medical probes for PET imaging of
cancer. In our previous work, we have synthesized radiolabeled
antimitotic agent T138067 analogues [11C]T138067 and
[18F]T138067. However, animal PET imaging results with these
tracers were disappointing.5 The specific binding of the tracers
to target microtubules in appropriate tumor models awaits
further investigations. In this ongoing study, we report the
design and synthesis of new carbon-11-labeled 7-aroyl-aminoin-
doline-1-sulfonamides, N-[1-(4-[11C]methoxy-benzenesulfonyl)-
2,3-dihydro-1Hindol-7-yl]-acetamide ([11C]4a), furan-2-carboxylic
acid [1-(4-[11C]methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-
7-yl]-amide ([11C]4b), 4-fluoro-N-[1-(4-[11C]methoxy-benzenesul-
fonyl)-2,3-dihydro-1H-indol-7-yl]-benzamide ([11C]4c) and N-[1-
(4-[11C]methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-iso-
nicotinamide ([11C]4d), as potential PET agents for imaging of
tubulin polymerization in cancers.
aDepartment of Radiology, Indiana University School of Medicine, 1345 West
16th Street, L3-202, Indianapolis, IN 46202, USA
bDepartment of Medicine, Indiana University School of Medicine, Indianapolis,
IN 46202, USA
*Correspondence to: Qi-Huang Zheng, Department of Radiology, Indiana
University School of Medicine, 1345 West 16th Street, L3-202, Indianapolis, IN
46202, USA.
E-mail: qzheng@iupui.edu
J. Label Compd. Radiopharm 2008, 51 6–11
Copyright r 2008 John Wiley & Sons, Ltd.

M. Wang et al.
(HBr),8 Lewis acids (BBr3, AlCl3/EtSH),9,10 and base (EtSNa).11
However, in all cases, an intractable red solid that could not be
characterized or a demethylated product with very low yield
was obtained. As a result of these unsuccessful attempts, we
chose to explore an alternative strategy, which is outlined in
Scheme 1. Benzylation of sodium 4-hydroxybenzenesulfonate
dihydrate was achieved by the protection of phenolic
hydroxyl group to give the corresponding ether 5 in 89% yield,
which was converted into sulfonyl chloride derivative 6 by
treatment with thionyl chloride in 95% yield.12 Coupling of
compound 6 with 5-bromo-7-nitroindoline produced 5-bromo-
1-(4-benzyloxy-benzenesulfonyl)-7-nitro-2,3-dihydro-1H-indole
(7) in 70% yield. Reduction of nitro group to amine group was
achieved with SnCl2 in ethanol to give 5-bromo-1-(4-benzyloxy-
benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl-amine (8) in 81%
yield,13 which was debrominated using Bu3SnH and AIBN to
afford 1-(4-benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-
yl-amine (9) in 80% yield. Coupling compound 9 with acyl
chloride or acetic anhydride to provide compounds 10a–d in
moderate to excellent yields, which were hydrogenated to
remove benzyl group to give the precursors 11a–d in 41–98%
yields.14
Results and discussion
Chemistry
Synthesis of reference standards was accomplished using
a modification of the previously reported procedures.4 Coupling
of commercially available 5-bromo-7-nitroindoline with 4-
methoxybenzenesulfonyl chloride in pyridine afforded the
corresponding sulfonamide derivative 5-bromo-1-(4-methoxy-
benzenesulfonyl)-7-nitro-2,3-dihydro-1H-indole (1) in 90% yield,
which was then reduced with Fe/NH4Cl in isopropanol to give 5-
bromo-1-(4-methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-
ylamine (2) in 92% yield. Free radical-mediated debromination
reaction was performed with Bu3SnH in the presence of 2,2’-
azobisisobutyronitrile (AIBN),6,7 and the resulting amine deriva-
tive 3 (71% yield) was coupled with acyl chloride or acetic
anhydride to produce the reference standards, 7-aroyl-aminoin-
doline-1-sulfonamides (4a–d) in moderate to excellent yields
(66–83% yields).
In order to prepare the demethylated precursors, we
envisioned that precursor compounds 11a–d could be prepared
by O-demethylation of target compounds 4a–d. A variety of
protocols were screened for this purpose including protic acid
Scheme 1
J. Label Compd. Radiopharm 2008, 51 6–11
Copyright r 2008 John Wiley & Sons, Ltd.
www.jlcr.org

M. Wang et al.
procedure.15 Melting points were determined on a MEL-TEMP
II capillary tube apparatus and were uncorrected. 1H NMR
spectra were recorded on a Varian Gemini 2000 200 MHz
FT-NMR spectrometer using tetramethylsilane (TMS) as an
internal standard. Chemical shift data for the proton resonances
were reported in parts per million (d scale) relative to internal
standard TMS (d 0.0), and coupling constants (J) were reported
in hertz (Hz). The low-resolution mass spectra were obtained
using a Bruker Biflex III MALDI-Tof mass spectrometer, and
the high-resolution mass spectra (HRMS) were obtained using a
Thermo MAT 95XP-Trap spectrometer. Chromatographic solvent
proportions are expressed on a volume:volume basis. Thin
layer chromatography was run using Analtech silica gel GF
uniplates (5 Â 10 cm2). Plates were visualized using UV light.
Normal phase flash chromatography was carried out on EM
Science silica gel 60 (230–400 mesh) with a forced flow of the
indicated solvent system in the proportions described below. All
moisture- and/or air-sensitive reactions were performed under a
positive pressure of nitrogen maintained by a direct line from a
nitrogen source.
Analytical HPLC was performed using a Prodigy (Phenomen-
ex) 5 mm C-18 column, 4.6 Â 250 mm; 3:1:1 CH3CN:MeOH:20 mM,
pH 6.7 KHPOÀ4 (buffer solution) mobile phase; flow rate 1.5 mL/
min; and UV (254 nm) and g-ray (NaI) flow detectors. Light C-18
Sep-Pak cartridges were obtained from Waters Corporate
Headquarters, Milford, MA. Semi-prep C-18 guard cartridge
column 1 Â 1 cm was obtained from E. S. Industries, Berlin, NJ,
and part number 300121-C18-BD 10 m. Sterile Millex-GS 0.22 mm
vented filter unit was obtained from Millipore Corporation,
Bedford, MA.
Radiochemistry
Synthesis of the target tracers, carbon-11-labeled 7-aroyl-ami-
noindoline-1-sulfonamides [11C]4a–d, is outlined in Scheme 2.
The precursor 11a, 11b, 11c, or 11d was labeled by [11C]methyl
triflate ([11C]CH3OTf)15,16 through O-[11C]methylation17 and iso-
lated by a simplified solid-phase extraction (SPE) purification18 to
produce corresponding pure target radiolabeled compound
[11C]4a, [11C]4b, [11C]4c, or [11C]4d with 40–55% radiochemical
yields, based on [11C]CO2, decay corrected to end of bombard-
ment (EOB). The large polarity difference between the phenolic
hydroxyl precursor and the labeled O-methylated product
permitted the use of SPE technique for purification of labeled
product from radiolabeling reaction mixture. Either a light C-18
Sep-Pak cartridge or a semi-prep C-18 guard cartridge column
was used in SPE purification technique. The reaction mixture was
loaded onto the cartridge by gas pressure. The cartridge was
washed with water to remove non-reacted [11C]CH3OTf, precursor
and reaction solvent, and then the final labeled product was
eluted with ethanol. Overall synthesis time was 10–15 min from
EOB. SPE technique is fast, efficient, and convenient and works
very well for the O-methylated tracer production. The radio-
synthesis was performed in an automated multi-purpose 11C-
radiosynthesis module, allowing measurement of specific activity
during synthesis.19,20 The specific activity was in a range of
74–111 GBq/mmol at the end of synthesis (EOS). Chemical purity
and radiochemical purity were determined by analytical high-
pressure liquid chromatography (HPLC) method.21 The chemical
purity of precursors and reference standards was 495%. The
radiochemical purity of target tracers was 498% as determined
by radio-HPLC through g-ray (NaI) flow detector, and the chemical
purity of target tracers was 493% as determined by reversed-
phase HPLC through UV flow detector.
Chemistry
5-Bromo-1-(4-methoxy-benzenesulfonyl)-7-nitro-2,3-dihydro-1H-in-
dole (1): Compound 1 was prepared using a modification of the
literature procedure4 as a yellow solid in 90% yield, m.p.
132–1331C. 1H NMR (CDCl3) d: 2.69 (t, J 5 7.7 Hz, 2H,
PhCH2CH2N), 3.87 (s, 3H, OCH3), 4.06 (t, J 5 7.7 Hz, 2H,
PhCH2CH2N), 6.93–6.97 (m, 2H, ArH), 7.50 (d, J 5 1.5 Hz, 1H,
ArH), 7.64–7.68 (m, 2H, ArH), 7.91 (d, J 5 1.5 Hz, 1H, ArH).
5-Bromo-1-(4-methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-
ylamine (2): Compound 2 was prepared using a modification of
the literature procedure4 as a white solid in 92% yield, m.p.
1731C (dec.). 1H NMR (CDCl3) d: 2.14 (t, J 5 7.4 Hz, 2H,
PhCH2CH2N), 3.85 (s, 3H, OCH3), 3.96 (t, J 5 7.5 Hz, 2H,
PhCH2CH2N), 6.54 (d, J 5 2.0 Hz, 1H, ArH), 6.74 (d, J 5 2.0 Hz,
1H, ArH), 6.85–6.89 (m, 2H, ArH), 7.54–7.58 (m, 2H, ArH).
1-(4-Methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-ylamine
(3): Compound 3 was prepared using a modification of the
literature procedure4 as a straw-colored solid in 71% yield,
m.p. 104–1061C. 1H NMR (CDCl3) d: 2.15 (t, J 5 7.3 Hz, 2H,
PhCH2CH2N), 3.83 (s, 3H, OCH3), 3.96 (t, J 5 7.3 Hz, 2H,
PhCH2CH2N), 6.42 (d, J 5 7.1 Hz, 1H, ArH), 6.60 (d, J 5 7.8 Hz,
1H, ArH), 6.81–6.95 (m, 3H, ArH), 7.51–7.56 (m, 2H, ArH).
N-[1-(4-Methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-
7-yl]-acetamide (4a): Compound 4a was prepared using a
modification of the literature procedure4 as a white solid in 75%
yield, m.p. 153–1541C (lit.4 154–1551C). 1H NMR (CDCl3) d:
2.21–2.24 (t and s, J 5 7.4 Hz, 5H, PhCH2CH2N and CH3CO), 3.83
(s, 3H, OCH3), 4.00 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), 6.77–6.85 (m,
3H, ArH), 7.13 (t, J 5 7.8 Hz, 1H, ArH), 7.44 (d, J 5 8.7 Hz, 2H, ArH),
8.10 (d, J 5 8.3 Hz, 1H, ArH), 9.34 (s, 1H, CONH).
Experimental
General
All commercial reagents and solvents were used without further
purification. [11C]CH3OTf was made according to a literature
Scheme 2
www.jlcr.org
Copyright r 2008 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2008, 51 6–11

M. Wang et al.
Furan-2-carboxylic acid [1-(4-methoxy-benzenesulfonyl)-2,3-di-
5-Bromo-1-(4-benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-indol-
hydro-1H-indol-7-yl]-amide (4b): Compound 4b was prepared 7-yl-amine (8): A mixture of compound 7 (10.3 g, 21.1 mmol) and
using a modification of the literature procedure4 as a white tin(II) chloride (19.4 g, 105.5 mmol) in EtOH (100 mL) was
solid in 83% yield, m.p. 170–1721C (lit.4 163–1641C). 1H NMR refluxed and stirred under nitrogen for 4 h. The solvent was
(CDCl3) d: 2.25 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), 3.83 (s, 3H, OCH3), evaporated and the residue was extracted with EtOAc. The
4.03 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), 6.53–6.55 (m, 1H, ArH), combined organic fraction was shaken with 2 M NaOH and
6.82–6.86 (m, 3H, ArH), 7.14–7.26 (m, 2H, ArH), 7.51(d, J 5 8.8 Hz, water. The organic layer was dried over anhydrous MgSO4 and
2H, ArH), 7.60 (s, 1H, ArH), 8.23 (d, J 5 8.1 Hz, 1H, ArH), 10.2 evaporated. The crude product was purified by column
(s, 1H, CONH).
4-Fluoro-N-[1-(4-methoxy-benzenesulfonyl)-2,3-dihydro-1H-in-
chromatography using EtOAc–hexanes (2:3) to afford com-
pound 8 as a white solid (7.8 g, 81%), m.p. 86–871C. 1H NMR
dol-7-yl]-benzamide (4c): Compound 4c was prepared using a (CDCl3) d: 2.13 (t, J 5 7.5 Hz, 2H, PhCH2CH2N), 3.95 (t, J 5 7.5 Hz,
modification of the literature procedure4 as a white solid in 75% 2H, PhCH2CH2N), d 5.09 (s, 2H, PhCH2O), 6.54 (d, J 5 1.5 Hz, 1H,
yield, m.p. 161–1621C (lit.4 184–1841C). 1H NMR (CDCl3) d: 2.26 (t, ArH), 6.74 (d, J 5 1.5 Hz, 1H, ArH), 6.91–6.98 (m, 2H, ArH),
J 5 7.3 Hz, 2H, PhCH2CH2N), 3.84 (s, 3H, OCH3), 4.03 (t, J 5 7.4 Hz, 7.35–7.42 (m, 5H, ArH), 7.53–7.60 (m, 2H, ArH). MS (CI, m/z): 132
2H, PhCH2CH2N), 6.83–6.87 (m, 3H, ArH), 7.14–7.24 (m, 3H, ArH), (100%), 458 (M1, 55%). HRMS (CI, m/z): calcd. for C21H19O3N2BrS
7.48–7.53 (m, 2H, ArH), 8.06–8.13 (m, 2H, ArH), 8.23–8.27 (m, 1H, 458.0294 (M1), found 458.0298.
ArH), 10.2 (s, 1H, CONH).
1-(4-Benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl-amine
(9): A mixture of compound 8 (6.82 g, 14.9 mmol), Bu3SnH
nicotinamide (4d): Compound 4d was prepared using a modifica- (11.8 mL, 44.6 mmol), and AIBN (0.25 g, 1.52 mmol) in toluene
N-[1-(4-Methoxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-4-iso-
tion of the literature procedure4 as a white solid in 66% yield, m.p. (100 mL) was stirred and heated to reflux for 25 h. The solvent
1
119–1201C (lit.4 219–2201C). H NMR (CDCl3) d: 2.28 (t, J 5 7.4 Hz, was evaporated and the residue was extracted with CH2Cl2. The
2H, PhCH2CH2N), 3.84 (s, 3H, OCH3), 4.04 (t, J5 7.4 Hz, 2H, combined organic layer was washed with water, dried over
PhCH2CH2N), 6.84–6.91 (m, 3H, ArH), 7.18–7.26 (m, 1H, ArH), 7.50 anhydrous Na2SO4, and evaporated. The crude product was
(d, J 59.1 Hz, 2H, ArH), 7.90–7.93 (m, 2H, ArH), 8.26 (d, J 5 8.3 Hz, purified by column chromatography using EtOAc–hexanes (1:4)
1H, ArH), 8.82 (d, J 5 6.8 Hz, 2H, ArH), 10.4 (s, 1H, CONH).
to afford compound 9 as a white solid (4.5 g, 80%), m.p.
1
Sodium 4-benzyloxybenzenesulfonate (5): A solution of sodium 83–841C. H NMR (CDCl3) d: 2.16 (t, J 5 7.3 Hz, 2H, PhCH2CH2N),
4-hydroxybenzenesulfonate dihydrate (20 g, 86.1 mmol) in 3.96 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), d 5.07 (s, 2H, PhCH2O), 6.43
anhydrous dimethyl formamide (DMF) (200 mL) was cooled to (d, J 5 7.3 Hz, 1H, ArH), 6.60 (d, J 5 8.0 Hz, 1H, ArH), 6.89–6.95 (m,
01C. NaH (60% dispersion in mineral oil, 4.13 g, 103.4 mmol) was 3H, ArH), 7.38 (s, 5H, ArH), 7.54 (d, J 5 8.8 Hz, 2H, ArH). MS (CI,
added under nitrogen. After being stirred for 20 min at 01C, m/z): 133 (100%), 380 (M1, 14%). HRMS (CI, m/z): calcd. for
benzyl bromide (12.3 mL, 103.4 mmol) was added and the C21H20O3N2S 380.1189 (M1), found 380.1202.
reaction mixture was stirred overnight at room temperature. A
N-[1-(4-Benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-
small amount of EtOAc was added to quench the reaction. The acetamide (10a): To a stirred solution of compound 9 (400 mg,
mixture was filtered and the residue was washed with EtOAc to 1.05 mmol) in pyridine (4 mL) was added acetic anhydride
afford compound 5 as a white solid (24.6 g, 89%). 1H NMR (0.13 mL, 1.37 mmol). The resulting solution was heated at 501C
(DMSO-d6) d: 5.11 (s, 2H, PhCH2O), 6.90–6.97 (m, 2H, ArH), for 6 h, poured into ice–water and extracted with EtOAc. The
7.31–7.48 (m, 5H, ArH), 7.48–7.56 (m, 2H, ArH).
combined organic layer was dried over anhydrous Na2SO4 and
4-Benzyloxybenzenesulfonyl chloride (6): To a suspension of evaporated. The crude product was purified by column
compound 5 (21 g, 73.4 mmol) in DMF (150 mL) was added chromatography using CHCl3–MeOH (100:1) to afford com-
1
thionyl chloride (6.62 mL, 90.9 mmol). The reaction mixture was pound 10a as a white solid (300 mg, 68%), m.p. 147–1481C. H
stirred for 5 min at room temperature, poured into ice–water NMR (CDCl3) d: 2.18–2.23 (t and s, J 5 7.4 Hz, 5H, PhCH2CH2N and
and extracted with CH2Cl2. The combined organic layer was CH3CO), 4.00 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), d 5.07 (s, 2H,
dried over anhydrous Na2SO4 and evaporated to give com- PhCH2O), 6.79 (d, J 5 7.1 Hz, 1H, ArH), 6.91 (d, J 5 9.1 Hz, 2H,
pound 6 as a white solid (19.8 g, 95%), m.p. 93–941C (lit.12 ArH), 7.13 (t, J 5 7.8 Hz, 1H, ArH), 7.38 (s, 5H, ArH), 7.46 (d,
1
92–941C). H NMR (CDCl3) d: 5.18 (s, 2H, PhCH2O), 7.08–7.16 (m, J 5 9.0 Hz, 2H, ArH), 8.10 (d, J 5 8.0 Hz, 1H, ArH), 9.33 (s, 1H,
2H, ArH), 7.35–7.45 (m, 5H, ArH), 7.94–8.02 (m, 2H, ArH).
5-Bromo-1-(4-benzyloxy-benzenesulfonyl)-7-nitro-2,3-dihydro-1H- calcd. for C23H22O4N2S 422.1295 (M1), found 422.1295.
indole (7): To a stirred solution of 5-bromo-7-nitroindoline (10 g, Furan-2-carboxylic acid [1-(4-benzyloxy-benzenesulfonyl)-2,3-di-
41.1 mmol) in pyridine (20 mL) was added compound 6 (15.1 g, hydro-1H-indol-7-yl]-amide (10b): To stirred solution of
CONH). MS (CI, m/z): 175 (100%), 422 (M1, 51%). HRMS (CI, m/z):
a
53.5 mmol). The resulting solution was heated under reflux for compound 9 (350 mg, 0.92 mmol) in pyridine (3.5 mL) was
39 h, poured into ice–water and extracted with CH2Cl2. The added 2-furoyl chloride (0.14 mL, 1.39 mmol). The resulting
combined organic layer was washed with brine, dried over solution was heated at 501C for 1.5 h, poured into ice–water
anhydrous Na2SO4, and evaporated. The crude product was and extracted with EtOAc. The combined layer was dried over
purified by gradient column chromatography with EtOAc–hex- anhydrous Na2SO4 and evaporated. The crude product
anes (3:1) to give compound 7 as a yellow solid (14.0 g, 70%), was purified by column chromatography using CHCl3–MeOH
m.p. 182–1831C. 1H NMR (CDCl3) d: 2.68 (t, J 5 7.7Hz, 2H, (250:3) to afford compound 10b as a white solid (360 mg,
PhCH2CH2N), 4.05 (t, J 5 7.7Hz, 2H, PhCH2CH2N), d 5.13 (s, 2H, 75%), m.p. 185–1861C. 1H NMR (CDCl3) d: 2.25 (t, J 5 7.3 Hz,
PhCH2O), 6.98–7.06 (m, 2H, ArH), 7.35–7.43 (m, 5H, ArH), 7.49 2H, PhCH2CH2N), 4.03 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), d 5.08
(d, J 5 1.8Hz, 1H, ArH), 7.62–7.70 (m, 2H, ArH), 7.92 (d, J 5 1.8Hz, (s, 2H, PhCH2O), 6.51–6.54 (m, 1H, ArH), 6.83 (d, J 5 7.3 Hz,
1H, ArH). MS (CI, m/z): 488 (M1, 93%), 490 (M112H, 100%). 1H, ArH), 6.92 (d, J 5 8.5 Hz, 2H, ArH), 7.16 (d, J 5 7.8 Hz, 1H,
HRMS (CI, m/z): calcd. for C21H17O5N2BrS 488.0036 (M1), found ArH), 7.22–7.26 (m, 1H, ArH), 7.38 (s, 5H, ArH), 7.51 (d, J 5 8.8 Hz,
488.0019.
2H, ArH), 7.59 (s, 1H, ArH), 8.23 (d, J 5 8.3 Hz, 1H, ArH), 10.2
J. Label Compd. Radiopharm 2008, 51 6–11
Copyright r 2008 John Wiley & Sons, Ltd.
www.jlcr.org

M. Wang et al.
(s, 1H, CONH). MS (CI, m/z): 227 (100%), 474 (M1, 23%). J 5 8.6 Hz, 2H, ArH), 7.60 (s, 1H, ArH), 7.77 (s, 1H, OH), 8.12 (d,
HRMS (CI, m/z): calcd. for C26H22O5N2S 474.1244 (M1), found J 5 8.3 Hz, 1H, ArH), 10.3 (s, 1H, CONH). MS (CI, m/z): 227 (100%),
474.1238.
4-Fluoro-N-[1-(4-benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-in-
dol-7-yl]-benzamide (10c): To a stirred solution of compound 9
384 (M1, 33%). HRMS (CI, m/z): calcd. for C19H16O5N2S 384.0774
(M1), found 384.0779.
4-Fluoro-N-[1-(4-hydroxy-benzenesulfonyl)-2,3-dihydro-1H-indol-
(400 mg, 1.05 mmol) in pyridine (4 mL) was added 4-fluoroben- 7-yl]-benzamide (11c): A solution of compound 10c (250 mg,
zoyl chloride (0.19 mL, 1.58 mmol). The resulting solution was 0.50 mmol) in THF (7 mL) and MeOH (3 mL) was hydrogenated at
heated at 711C for 1 h, poured into ice–water and extracted with atmospheric pressure over 10% Pd–C (40 mg) for 6 h. The
EtOAc. The combined organic layer was dried over anhydrous catalyst was removed by filtration, and the solution was
Na2SO4 and evaporated. The crude product was purified by evaporated to afford compound 11c as a white solid (205 mg,
1
column chromatography using CHCl3–MeOH (100:1) to afford 98%), m.p. 203–2051C. H NMR (CDCl3) d: 2.27 (t, J 5 7.3 Hz, 2H,
compound 10c as a white solid (322 mg, 55%), m.p. 170–1721C. PhCH2CH2N), 4.01 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), 6.78–6.87 (m,
1H NMR (CDCl3) d: 2.25 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), 4.03 (t, 3H, ArH), 7.11–7.22 (m, 3H, ArH), 7.38–7.43 (m, 2H, ArH),
J 5 7.3 Hz, 2H, PhCH2CH2N), 5.09 (s, 2H, PhCH2O), 6.84 (d, 8.03–8.16 (m, 3H, ArH), 10.3 (s, 1H, CONH). MS (CI, m/z): 255
J 5 7.4 Hz,1H, ArH), 6.93 (d, J 5 8.8 Hz, 2H, ArH), 7.13–7.26 (m, 3H, (100%), 412 (M1, 33%). HRMS (CI, m/z): calcd for C21H17O4N2FS
ArH), 7.39 (s, 5H, ArH), 7.51 (d, J 5 8.8 Hz, 2H, ArH), 8.05–8.10 (m, 412.0888 (M1), found 412.0881.
2H, ArH), 8.25 (d, J 5 8.3 Hz, 1H, ArH), 10.2 (s, 1H, CONH). MS (CI,
m/z): 55 (100%), 502 (M1, 32%). HRMS (CI, m/z): calcd. for isonicotinamide (11d): A solution of compound 10d (240 mg,
C28H23O4N2FS 502.1357 (M1), found 502.1357.
0.49 mmol) in THF (7 mL) and MeOH (3 mL) was hydrogenated at
N-[1-(4-Hydroxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-4-
N-[1-(4-Benzyloxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-4- atmospheric pressure over 10% Pd–C (40 mg) overnight. The
isonicotinamide (10d): A mixture of compound 9 (450 mg, catalyst was removed by filtration, and the solution was
1.18 mmol), isonicotinoyl chloride hydrochloride (254 mg, evaporated. The product was purified by column chromato-
1.42 mmol,) and cesium carbonate (925 mg, 2.84 mmol) in graphy using CHCl3–MeOH–NH3 Á H2O (200:10:1) to afford
acetonitrile (30 mL) was stirred and heated at 851C for 3 h. The compound 11d as a white solid (80 mg, 41%), m.p. 2101C
1
solvent was evaporated and the residue was added to water and (dec.). H NMR (DMSO-d6) d: 2.29 (t, J 5 7.3 Hz, 2H, PhCH2CH2N),
extracted with CH2Cl2. The combined organic layer was washed 4.03 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), 6.82 (d, J 5 8.7 Hz, 2H, ArH),
with water, dried over anhydrous Na2SO4 and evaporated. The 7.00 (d, J 5 7.8 Hz, 1H, ArH), 7.20 (d, J 5 7.7 Hz, 1H, ArH), 7.42 (d,
crude product was purified by column chromatography using J 5 8.4 Hz, 2H, ArH), 7.85–7.92 (m, 3H, ArH), 8.84 (d, J 5 5.9 Hz,
CHCl3–MeOH (100:1) to afford compound 10d as a white solid 2H, ArH), 10.3 (s, 1H, OH), 10.7 (s, 1H, CONH). MS (CI, m/z): 238
(370 mg, 64%), m.p. 185–1861C. 1H NMR (CDCl3) d: 2.27 (t, (100%), 395 (M1, 27%). HRMS (CI, m/z): calcd for C20H17O4N3S
J 5 7.3 Hz, 2H, PhCH2CH2N), 4.04 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), 395.0934 (M1), found 395.0920.
5.09 (s, 2H, PhCH2O), 6.86–6.95 (m, 3H, ArH), 7.24 (d, J 5 7.8 Hz,
1H, ArH), 7.38 (s, 5H, ArH), 7.51 (d, J 5 8.8 Hz, 2H, ArH), 7.91 (d,
J 5 4.4 Hz, 2H, ArH), 8.26 (d, J 5 8.0 Hz, 1H, ArH), 8.83 (s, 2H, ArH),
10.4 (s, 1H, CONH). MS (CI, m/z): 485 (M1, 77%), 486 (M111,
100%). HRMS (CI, m/z): calcd for C27H24O4N3S 486.1482 (M11H),
found 486.1491.
Radiochemistry
General method for the preparation of carbon-11-labeled 7-
aroyl-aminoindoline-1-sulfonamides, N-[1-(4-[11C]methoxy-ben-
zenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-acetamide ([11C]4a),
furan-2-carboxylic acid [1-(4-[11C]methoxy-benzenesulfonyl)-2,3-
dihydro-1H-indol-7-yl]-amide ([11C]4b), 4-fluoro-N-[1-(4-[11C]meth-
oxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-benzamide
([11C]4c) and N-[1-(4-[11C]methoxy-benzenesulfonyl)-2,3-dihy-
dro-1H-indol-7-yl]-isonicotinamide ([11C]4d).
N-[1-(4-Hydroxy-benzenesulfonyl)-2,3-dihydro-1H-indol-7-yl]-
acetamide (11a): A solution of compound 10a (250 mg,
0.59 mmol) in tetrahydrofuran (THF) (7 mL) and MeOH (3 mL)
was hydrogenated at atmospheric pressure over 10% Pd–C
(40 mg) for 6 h. The catalyst was removed by filtration, and
the solution was evaporated to afford compound 11a as a
[11C]CO2 was produced by the 14N(p,a)11C nuclear reaction in
small volume (9.5 cm3) aluminum gas target (CTI) from 11 MeV
proton cyclotron on research purity nitrogen (11% O2) in a
Siemens radionuclide delivery system (Eclipse RDS-111). The
phenolic hydroxyl precursor 11a, 11b, 11c, or 11d (0.1–0.3 mg,
0.3–0.7 mM) was dissolved in CH3CN (300 mL). To this solution
was added 3 N NaOH (2 mL, 6 mM). The mixture was transferred to
a small reaction vial. No carrier-added (high specific activity)
[11C]CH3OTf that was produced by the gas-phase production
method15 from [11C]CO2 through [11C]CH4 and [11C]CH3Br with
silver triflate (AgOTf) column was passed into the reaction vial,
which was cooled to 01C, until radioactivity reached a maximum
(ꢀ2 min), and then the reaction vial was isolated and heated at
801C for 3 min. The contents of the reaction vial were diluted
with NaHCO3 (1 mL, 0.1 M). The reaction tube was connected to
either a light C-18 Sep-Pak cartridge or a semi-prep C-18 guard
cartridge column. The labeled product mixture solution was
passed onto the cartridge for SPE purification by gas pressure.
The cartridge was washed with H2O (2 Â 3 mL), and the aqueous
washing was discarded. The product was eluted from the
1
white solid (186 mg, 95%), m.p. 2321C (dec.). H NMR (DMSO-
d6) d: 2.10 (s, 3H, CH3CO), 2.22 (t, J 5 7.3 Hz, 2H, PhCH2CH2N),
3.97 (t, J 5 7.4 Hz, 2H, PhCH2CH2N), 6.78 (d, J 5 8.7 Hz, 2H,
ArH), 6.87 (d, J 5 7.3 Hz, 1H, ArH), 7.11 (t, J 5 7.9 Hz, 1H, ArH),
7.34 (d, J 5 8.8 Hz, 2H, ArH), 7.82 (d, J 5 7.7 Hz, 1H, ArH), 9.37
(s, 1H, CONH), 10.6 (s, 1H, OH). MS (CI, m/z): 332 (M1, 100%).
HRMS (CI, m/z): calcd. for C16H16O4N2S 332.0825 (M1), found
332.0819.
Furan-2-carboxylic acid [1-(4-hydroxy-benzenesulfonyl)-2,3-dihy-
dro-1H-indol-7-yl]-amide (11b): A solution of compound 10b
(250 mg, 0.53 mmol) in THF (10 mL) and MeOH (3 mL) was
hydrogenated at atmospheric pressure over 10% Pd–C (30 mg)
overnight. The catalyst was removed by filtration, and the
solution was evaporated. The product was purified by column
chromatography using CHCl3–MeOH (250:6) to afford com-
1
pound 11b as a white solid (150 mg, 74%), m.p. 158–1591C. H
NMR (CDCl3) d: 2.27 (t, J 5 7.3 Hz, 2H, PhCH2CH2N), 4.01 (t,
J 5 7.4 Hz, 2H, PhCH2CH2N), 6.53–6.56 (m, 1H, ArH), 6.80–6.87 (m,
3H, ArH), 7.14 (t, J 5 7.8 Hz, 1H, ArH), 7.27 (s, 1H, ArH), 7.41 (d,
www.jlcr.org
Copyright r 2008 John Wiley & Sons, Ltd.
J. Label Compd. Radiopharm 2008, 51 6–11

M. Wang et al.
column with EtOH (2 Â 3 mL), and then passed onto a rotatory University, which is supported in part by Lilly Endowment Inc.
evaporator. The solvent was removed by evaporation under The authors would like to thank Dr Bruce H. Mock, Barbara E.
vacuum. The labeled product [11C]4a, [11C]4b, [11C]4c, or [11C]4d Glick-Wilson and Michael L. Sullivan for their assistance in
was formulated with saline, whose volume was dependent upon production of [11C]CH3OTf. The referees’ criticisms and editor’s
the use of the labeled product in tissue biodistribution studies comments for the revision of the manuscript are greatly
(ꢀ6 mL, 3 Â 2 mL) or in PET imaging studies (1–3 mL). Total appreciated.
radioactivity was assayed and the total volume (1.0–6.0 mL) was
noted. The overall synthesis time including SPE purification and
formulation was 10–15 min. The radiochemical yields were
40–55% decay corrected to EOB from [11C]CO2 and 28–39% at
EOS, respectively. Retention times in the analytical HPLC system
References
were tR 11a 5 2.27 min, tR 4a 5 2.79 min, tR [11C]4a 5 2.79 min; tR
[1] C. E. Comstock, K. E. Knudsen, Cell Cycle 2007, 6, 1307–1313.
11b 5 2.59 min, tR 4b 5 3.26 min, tR [11C]4b 5 3.26 min; tR
[2] T. Y. Liaw, M. H. Chang, M. Kavallaris, Curr. Drug Targets 2007, 8,
11c 5 3.25 min, tR 4c 5 4.37 min, tR [11C]4c 5 4.37 min; and tR
739–749.
[3] A. Jordan, J. A. Hadfield, N. J. Lawrence, A. T. McGown, Med. Res.
Rev. 1998, 18, 259–296.
[4] J-Y. Chang, H-P. Hsieh, C-Y. Chang, K-S. Hsu, Y-F. Chiang, C-M.
11d 5 1.94 min, tR 4d 5 3.46 min, tR [11C]4d 5 3.46 min.
Conclusion
Chen, C-C. Kuo, J-P. Liou, J. Med. Chem. 2006, 49, 6656–6659.
[5] X. Fei, Q-H. Zheng, J-Q. Wang, K. L. Stone, T. D. Martinez, K. D.
Miller, G. W. Sledge, G. D. Hutchins, Bioorg. Med. Chem. Lett. 2004,
14, 1247–1251.
[6] D. P. Curran, C. T. Chang, J. Org. Chem. 1989, 54, 3140–3157.
[7] G. Cardillo, M. Orena, S. Sandri, C. Tomasini, J. Org. Chem. 1984, 49,
3951–3953.
[8] G. R. Pettit, H. Hoffmann, D. L. Herald, J. McNulty, A. Murphy, K. C.
Higgs, E. Hamel, N. E. Lewin, L. V. Pearce, P. M. Blumberg, R. K.
Pettit, J. C. Knight, J. Org. Chem. 2004, 69, 2251–2256.
[9] Y. W. Kim, J. C. Hackett, R. W. Brueggemeier, J. Med. Chem. 2004,
47, 4032–4040.
[10] M. Gao, D. Kong, A. Clearfield, Q-H. Zheng, Bioorg. Med. Chem. Lett.
2006, 16, 2229–2233.
[11] J. A. Dodge, M. G. Stocksdale, M. G. Stocksdale, K. J. Fahey, C. D.
Jones, J. Org. Chem. 1995, 60, 739–741.
[12] E. A. Arvanitis, D. Craig, A. P. Timm, ARKIVOC 2002, 9, 19–27.
[13] D. F. Shi, T. D. Bradshaw, S. Wrigley, C. J. McCall, P. Lelieveld, I.
Fichtner, M. F. G. Stevens, J. Med. Chem. 1996, 39, 3375–3384.
[14] M. P. Leese, B. Leblond, A. Smith, S. P. Newman, A. D. Fiore, G. D.
Simone, C. T. Supuran, A. Purohit, M. J. Reed, B. V. L. Potter, J. Med.
Chem. 2006, 49, 7683–7696.
An efficient and convenient chemical and radiochemical
synthesis of phenolic hydroxyl precursors, reference standards
7-aroyl-aminoindoline-1-sulfonamides, and target tracers car-
bon-11-labeled 7-aroyl-aminoindoline-1-sulfonamides has been
well developed. The synthetic methodology employed classical
organic chemistry such as the free radical-mediated debromina-
tion in the presence of AIBN and Bu3SnH and deprotecting
hydrogenation of benzyl group. Carbon-11 labeling at oxygen
position through O-[11C]methylation was incorporated effi-
ciently using [11C]CH3OTf, a signature reaction of carbon-11
radiochemistry from our laboratory. Radiosynthesis produced
new probes in amounts and purity suitable for the preclinical
application in animal studies using PET. Labeled product
suitable for injection, with the higher specific radioactivities in
a range of 74–111 GBq/mmol at EOS, can be obtained within
15 min from EOB including fast SPE purification and formulation.
These chemistry results combined with the reported in vitro
biological data encourage further in vivo biological evaluation
of carbon-11-labeled 7-aroyl-aminoindoline-1-sulfonamides as
new potential PET agents for imaging of cancer tubulin
polymerization.
[15] B. H. Mock, G. K. Mulholland, M. T. Vavrek, Nucl. Med. Biol. 1999, 26,
467–471.
[16] D. M. Jewett, Appl. Radiat. Isot. 1992, 43, 1383–1385.
[17] Q-H. Zheng, X. Liu, X. Fei, J-Q. Wang, D. W. Ohannesian, L. C.
Erickson, K. L. Stone, G. D. Hutchins, Nucl. Med. Biol. 2003, 30,
405–415.
[18] M. Wang, M. Gao, B. H. Mock, K. D. Miller, G. W. Sledge, G. D.
Hutchins, Q-H. Zheng, Bioorg. Med. Chem. 2006, 14, 8599–8607.
[19] B. H. Mock, Q-H. Zheng, T. R. DeGrado, J. Label. Compd.
Radiopharm. 2005, 48, S225.
[20] B. H. Mock, B. E. Glick-Wilson, Q-H. Zheng, T. R. DeGrado, J. Label.
Compd. Radiopharm. 2005, 48, S224.
Acknowledgement
This work was partially supported by the Susan G. Komen for
the Cure grant BCTR0504022, Breast Cancer Research Founda-
tion, and Indiana Genomics Initiative (INGEN) of Indiana [21] Q-H. Zheng, B. H. Mock, Biomed. Chromatogr. 2005, 19, 671–676.
J. Label Compd. Radiopharm 2008, 51 6–11
Copyright r 2008 John Wiley & Sons, Ltd.
www.jlcr.org