Design, synthesis and preliminary bioactivity studies of 1,2-dihydrobenzo[d]isothiazol-3-one-1,1-dioxide hydroxamic acid derivatives as novel histone deacetylase inhibitors

Article abstract of DOI:10.1016/j.bmc.2014.01.045

Histone deacetylase (HDAC) is a clinically validated target for antitumor therapy. In order to increase HDAC inhibition and efficiency, we developed a novel series of saccharin hydroxamic acids as potent HDAC inhibitors. Among them, compounds 11e, 11m, 11

Full text of DOI:10.1016/j.bmc.2014.01.045

Bioorganic & Medicinal Chemistry 22 (2014) 1529–1538
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Design, synthesis and preliminary bioactivity studies
of 1,2-dihydrobenzo[d]isothiazol-3-one-1,1-dioxide hydroxamic acid
derivatives as novel histone deacetylase inhibitors
Leiqiang Han a, Lei Wang a, Xuben Hou a, Huansheng Fu a, Weiguo Song a, Weiping Tang b, Hao Fang a,
⇑
a Department of Medicinal Chemistry, Key Laboratory of Chemical Biology (Ministry of Education), School of Pharmacy, Shandong University,
44 West Wenhua Rd, Ji’nan 250012, PR China
b Division of Pharmaceutical Sciences, School of Pharmacy, University of Wisconsin, Madison 53705, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Histone deacetylase (HDAC) is a clinically validated target for antitumor therapy. In order to increase
HDAC inhibition and efficiency, we developed a novel series of saccharin hydroxamic acids as potent
HDAC inhibitors. Among them, compounds 11e, 11m, 11p exhibited similar or better HDACs inhibitory
activity compared with the approved drug SAHA. Further biological evaluation indicated that compound
11m had potent antiproliferative activities against MDA-MB-231 and PC-3.
Received 24 November 2013
Revised 22 January 2014
Accepted 23 January 2014
Available online 1 February 2014
Ó 2014 Elsevier Ltd. All rights reserved.
Keywords:
1,2-Dihydrobenzo[d]isothiazol-3-one-1,1-
dioxide
Histone deacetylase inhibitor
Antiproliferative
1. Introduction
O
O
N
Histone acetylation and deacetylation play important roles in
the regulation of gene transcription and the modulation of chroma-
tin structure. The levels of histone acetylation are determined by
the activities of histone acetyltransferases and histone deacety-
lases (HDACs). HDAC is associated with a number of oncogenes
and tumor suppressor genes and can be aberrantly expressed
and/or inappropriately activated in cancer cells.1 Presumably due
to their involvement in repressing transcription, various HDAC iso-
forms are overexpressed in different cancers and as such are valid
targets for cancer treatment.2 HDAC inhibitors (HDACi) have there-
fore recently emerged as novel antitumor agents against malignan-
cies. They regulate gene expression by enhancing the acetylation of
histones and non-histone proteins, which include transcription
factors, transcription regulators, signal transduction mediators,
and DNA repair enzymes.1 The cumulative result of these activities
is the inhibition of tumor growth.
H
O
H
NH
S
S
O
H
N
O
O
NHOH
NH
H
O
NH
O
Vorinostat (SAHA) 1
RoMidepsin (FK228) 2
Figure 1. Approved drugs of HDACIs.
unsaturated linker and a surface recognition cap group that inter-
acts with the amino acid residues at the surface of the HDAC
(Fig. 2). Extensive reports have aimed to improve the HDAC inhibi-
tion profile by manipulating the surface recognition cap group and
linker region while retaining the hydroxamic acid as ZBG.4
In our previous studies, we developed N-hydroxybenzamide,5
1,3,4-thiadiazole,6 and tetrahydroisoquinoline7–9 derivatives as no-
vel HDAC inhibitors. Especially, tetrahydroisoquinoline derivatives
show good inhibitory activities against HDAC and possess better
antiproliferative activities in the xenograft models. In our on-going
studies, the 1,2-dihydrobenzo[d]isothiazol-3-one-1,1-dioxide (sac-
charin) was chosen as a cap group of HDAC inhibitors because it
was structurally similar to tetrahydroisoquinoline and it was also
To date, two histone deacetylase inhibitors (Fig. 1), Vorinostat 1
(SAHA) and Romidepsin 2 (FK228) are approved for the treatment
of cutaneous T-cell lymphoma (CTCL).3 The common pharmaco-
phore of HDACi consists of three domains: a zinc-binding group
(ZBG) that chelates the active site Zn2+ ion, a saturated or
⇑
Corresponding author. Tel./fax: +86 531 88382731.
E-mail address: haofangcn@sdu.edu.cn (H. Fang).
http://dx.doi.org/10.1016/j.bmc.2014.01.045
0968-0896/Ó 2014 Elsevier Ltd. All rights reserved.

1530
L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
Cap group
O
in Schemes 2 and 3. When the sodium salts of saccharin or 4 were
heated with -bromoalkylcarboxylic ester in DMF at 100 °C, the
N-alkylation products were obtained. Hydrolysis of the esters by
hot concentrated HCl provided the target acids 7a–7h. Acids 7i,
7j, 7k were synthesized by direct alkylation under condition a.
Final hydroxamic acids 8a–8k were prepared by a mixed anhy-
dride approach according to literature procedures.5
ZBG
Linker
x
O
R
(CH2)
n
S
NHOH
N
O
O
To gain more diversity, carboxylic acids 10a–10p were synthe-
sized from 7d, 7h, and 7j by hydrogenation and amide formation as
shown in Scheme 3. Final products 11a–11p were obtained from
10a–10p following the same method shown in Scheme 2.
Figure 2. HDACi pharmacophore model and our saccharin-based hydroxamic acid
derivative.
found in many clinically used agents.10–12 Although the parent
compound (R = H, Fig. 2) was mentioned in a patent,13 variation
of R group for the structure in Figure 2 and related SAR were not
reported. Herein we report the synthesis, enzyme inhibition and
antiproliferative activities against tumor cell lines of saccharin
hydroxamic acid derivatives with various R groups.
3. Results and discussion
HDAC inhibitory activities of the saccharin hydroxamates were
evaluated by the Color de Lys assay and the results were tabulated
as IC50 values in Table 1. According to the data in Table 1, both the
linkers and the substituents on saccharin have significant impacts
on the inhibitory activities against HDAC. For example, the com-
pounds with shorter linker (n = 1–4), such as 8a–8h, showed poor
inhibition on HDAC. When the length of linker reached to five
methylene units, the compounds (e.g. 8i and 8j) had good inhibi-
tory activities with IC50 value in the micromolar range. This result
suggested that the length of the linker was crucial to binding affin-
ities. Moreover, activities of compounds 11a–11e also confirmed
this hypothesis.
2. Chemistry
In order to develop the saccharin hydroxamates, we first syn-
thesized key intermediate 4 in Scheme 1 following reported proce-
dures.14 Aryl iodide 6 was then prepared from intermediate 4 by
hydrogenation and Sandmeyer reaction.
The preparation of various saccharin hydroxamic acid deriva-
tives with the general structure shown in Figure 2 are described
O
S
O
S
O
S
NO2
O
O
O
O2N
H2N
I
a
b
c
NH
NH
NH
H3C
SO2NH2
O
O
O
6
4
5
3
Scheme 1. Synthesis of intermediate 4, 6. Reagents: (a) CrO3, H2SO4, H2O; (b) H2, Pd/C, THF; (c) CH3COOH, HCl, NaNO2, KI, H2O.
O
S
O
O
S
R1
O
O
S
O
R1
O
a,
b
n
R1
c
OH
NH
Br
+
+
n
NHOH
N
OEt
n
N
O
O
O
O
saccharin, 4
O
7a-7k
8a-8k
a
O
O
S
R1
OH
NH
Br
O
O
saccharin, 4, 6
Scheme 2. Synthesis of compounds 8a–8k. Reagents: (a) NaHCO3, DMF; (b) HCl (concd); (c) iBuCO2Cl, Et3N, NH2OH, THF.
O
S
O
S
O
S
O
O
H
N
O2N
H2N
O
R2
OH
OH
b
a
OH
N
N
n
n
N
n
O
O
O
O
O
O
O
9a-9c
7d, 7h, 7j
10a-10p
O
S
H
O
R2
N
c
NHOH
N
n
O
O
O
11a-11p
Scheme 3. Synthesis of compounds 11a–11p. Reagents: (a) H2, Pd/C, THF; (b) (i) R2CO2H, SOCl2; (ii) NaHCO3, THF; (c) iBuCO2Cl, Et3N, NH2OH, THF.

L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
1531
Table 1
In vitro HDAC activity
O
O
R
S
NHOH
n
N
O
O
Compd
R
n
IC50 of HDACa
>5
(l
M)
Compd
R
n
IC50 of HDACa
0.155 0.015
(lM)
8a
1
8k
5
I
H
O
O2N
8b
8c
1
2
>5
11e
11f
5
5
0.152 0.032
N
H
O
H
N
H
>5
>5
O
O2N
O
N
H
8d
2
2
2
>5
>5
>5
11g
11h
11i
5
5
5
0.353 0.091
0.170 0.068
0.156 0.027
O
O
O
O
N
H
N
H
11a
11b
I
O
O
N
H
N
H
O
O
H
N
O
O
N
H
O
11c
2
>5
11j
5
0.244 0.055
O
O
H
Br
8e
8f
3
3
4
4
>5
>5
>5
>5
11k
11l
5
5
5
5
0.438 0.019
0.592 0.067
0.113 0.023
1.25 0.388
N
H
O
O2N
H
N
H
O
O
8g
8h
11m
11n
N
H
S
O2N
N
H
O
O
N
N
H
11d
4
0.417 0.088
11o
5
5
0.170 0.023
H
F
O
H
N
H
8i
8j
5
5
4.39 0.051
3.41 0.042
11p
0.096 0.014
0.135 0.014
O2N
O
H
N
O2N
SAHA
NHOH
O
a
All of the compounds were assayed three times, and their inhibition results are means of the three independent assays and expressed with standard deviations.

1532
L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
Table 2
To further examine the saccharin hydroxamic acid HDAC
Antiproliferative activities of representative compoundsa
inhibitors at the cellular level, active compounds 11e, 11m and
11p were chosen as the representatives to evaluate their antipro-
liferative activities against the growth of cancer cells. Four tumor
cell lines, MDA-MB-231 (breast cancer cell), PC-3 (prostatic can-
cer cell), KG1 and K562 (myelogenous leukemia cell) were tested
using MTT assay. The IC50 values were summarized in Table 2.
According to the inhibition data, human myelogenous leukemia
cells (KG1) was the most sensitive to our saccharin HDACIs. It ap-
peared that all of these compounds possessed better growth inhi-
bition towards blood cancer than solid tumor cell. Among them,
11m had the most similar inhibition profile and showed higher
inhibitory potency on MDA-MB-231and PC-3 compared with
SAHA.
In order to understand the interaction between these inhibitors
and HDAC, we docked compound 11p and SAHA in the active site
of HDAC2 (PDB code: 3MAX) using AutoDock4.215 (Fig. 3). The re-
sult suggested that 11p possessed a similar binding mode to SAHA
in the active site of HDAC2. The hydroxamic acid moiety of 11p and
SAHA could chelate Zn2+ ion as well as form hydrogen bonds with
Glu154 and Tyr308 in the HDAC2 active site. In addition, the nitro-
gen atom in amide group of 11p could form another hydrogen
bond with Leu267.
IC50 (lM)
MDA-MB-231
PC-3
KG1
K562
SAHA
11e
11m
11p
4.61 0.80
5.15 1.61
4.34 0.41
7.72 1.44
9.79 3.28
12.63 3.81
9.28 2.17
12.45 2.16
1.15 0.01
2.21 0.01
1.66 0.32
2.64 0.44
3.77 0.13
4.17 0.81
6.02 0.82
8.90 1.61
a
Each value was reproduced in three independent assays and expressed with
standard deviations.
In addition, the substituents on saccharin also affected the
inhibitory activities. For example, the minor differences in com-
pounds 8i–8k are the substituents on saccharin ring and they led
to the change of IC50 values from 4.4
stituent (8k, IC50 = 0.16 M) showed similar inhibitory activity
with positive control SAHA (IC50 = 0.13 M). But the nitro substitu-
ent (8j, IC50 = 3.41 M) did not exhibit improvement for the bind-
ing affinities compared with 8i (IC50 = 4.4 M), which did not have
lM to 0.15 lM. The iodo sub-
l
l
l
l
any substituent. These results indicated that the substituent on the
6-position of saccharin might be necessary for surface recognition
and could be investigated further.
To test this hypothesis, 11e–11p were designed and synthe-
sized. Our preliminary biological evaluations suggested that most
of these compounds had similar or even better HDACs inhibitory
activities compared with SAHA. But 11f, 11n bearing biphenyl
and styrene showed poor inhibition, which suggested a large sub-
stituent on this position was unfavorable for the interaction be-
tween the inhibitor and the narrow channel of HDAC binding
pocket. In addition, compound 11l with slightly poor inhibition
activity may be also due to the steric effect derived from the naph-
athyl fragment. Other compounds, such as 11e, 11m and 11p, pos-
sessed similar and even better HDAC inhibitory activity compared
with the approved drug SAHA.
4. Conclusions
In conclusion, we have designed and synthesized a novel series
of saccharin-based hydroxamic acid HDAC inhibitors, which have
different linkers and substitutions in saccharin ring as the surface
recognition motifs. The strong enzymatic inhibition of compounds
8k, 11e, 11h–11j, 11m, 11o and 11p indicate that the linker with
five carbon units between the ZBG and the saccharin ring bearing
a suitable substituent is optimal for potency. These results suggest
that saccharin-based hydroxamate derivatives could be used as
lead compounds to develop novel anticancer agents.
Figure 3. (a) The docking modes of compound 11p (depicted in orange) and SAHA (depicted in cyan) in the active site of HDAC2; (b) Proposed binding preference of
compound 11p; (c) Proposed binding preference of SAHA. The pictures were produced using UCSF chimera software.16

L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
1533
(m, J = 7.2 Hz, 2H), 2.18 (t, J = 7.2 Hz, 2H), 3.57 (t, J = 7.2 Hz, 2H),
6.85 (s, 2H), 6.92 (d, J = 7.8 Hz, 1H), 7.03 (s, 1H), 7.66 (d,
J = 8.4 Hz, 1H), 12.00 (s, 1H). 13C NMR (DMSO-d6): 23.89, 25.58,
27.84, 33.40, 37.97, 103.08, 111.50, 117.90, 126.39, 139.57,
155.48, 158.98, 174.33. HRMS (AP-ESI) m/z Calcd for C13H16N2O5S
[M+H]+ 313.0853. Found: 313.0862.
5. Experimental section
5.1. Chemistry: general procedures
All materials and reagents used in this work are analytical re-
agents without further purification. All reactions except those in
aqueous media were carried out by standard techniques for the
exclusion of moisture. All reactions were monitored by thin-layer
chromatography on 0.25 mm silica gel plates (60GF-254) and visu-
alized with UV light, chloride ferric or iodine vapor. Melting points
were determined on an electrothermal melting point apparatus
without correction. ESI-MS was determined on an API 4000 spec-
trometer. NMR spectra were obtained on a Bruker DRX spectrom-
eter (600 MHz) and a Bruker Avance spectrometer (300 MHz). The
chemical shifts are defined as d values (parts per million) relative
to TMS internal standard. Significant 1H NMR data are reported
in the following order: multiplicity (s, singlet; d, doublet; t, triplet;
m, multiplet) number of protons. HRMS spectrums were conducted
on an Agilent 6510 Quadrupole Time-of-Flight LC/MS deliver. All
reported yields are for purified products.
5.1.3. 6-Iodobenzo[d]isothiazol-3(2H)-one 1,1-dioxide (6)
Compound 6 was synthesized according to literature proce-
dures.17 Yield: 95%, mp: 224–226 °C. 1H NMR (CDCl3) d 7.75 (d,
J = 7.8 Hz, 1H), 8.20 (d, J = 7.8 Hz, 1H), 8.26 (s, 1H). MS (ESI) m/z:
308.2 [MꢀH]ꢀ.
5.1.4. General procedure for the synthesis of 7a–7h
Saccharin or 4 (6.6 mmol) was added to a solution of sodium
bicarbonate (1.1 g, 13.2 mmol) in 3 ml of DMF. The corresponding
ester (7.9 mmol) was added slowly and the resulting solution was
stirred for 4 h at 60–80 °C. The mixture was poured into 15 ml of
water to give the crude product. It can be recrystallized from EtOH
to give pure product.
The appropriate ester (1.00 mmol) was suspended in 3 ml of
concentrated hydrochloric acid and heated under stirring at
100 °C until hydrolysis was completed (3–4 h, TLC analysis). After
cooling to room temperature, the reaction mixture was diluted
with water and the precipitated carboxylic acid product was col-
lected and purified by recrystallization (n-hexane/ethyl acetate).
5.1.1. 6-Nitrobenzo[d]isothiazol-3(2H)-one 1,1-dioxide (4)
To a solution of chromium trioxide (9.0 g, 900 mmol) in water
(67 ml), concentrated sulfuric acid (83.5 ml) was added gradually.
The mixture was added 2-methyl-5-nitrobenzenesulfonamide 3
(4.32 g, 20 mmol) and then stirred at room temperature for 24 h.
Crude product was obtained by filtration and then washed with
water. The filter cake was stirred in 10% sodium bicarbonate solu-
tion and the insoluble residue was removed by filtration. The fil-
trate was acidified with 5% hydrochloric acid solution to generate
the purified product with 55% yield, mp: 203–205 °C. 1H NMR
(DMSO-d6) d 7.91 (d, J = 8.4 Hz, 1H), 8.47 (dd, J = 7.8 Hz, 1.8 Hz,
1H), 8.54 (s, 1H). MS (ESI) m/z: 227.1 [MꢀH]ꢀ.
5.1.4.1. 2-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)acetic
acid (7a). Yield: 67%, mp: 211–213 °C. 1H NMR (DMSO-d6) d
4.49 (s, 2H), 8.02 (td, J = 7.8 Hz 1.2 Hz, 1H), 8.08 (td, J = 7.8 Hz
1.2 Hz, 1H), 8.15 (dd, J = 7.8 Hz 0.6 Hz, 1H), 8.35 (d, J = 7.8 Hz,
1H), 13.37 (s, 1H). MS (ESI) m/z: 240.2 [MꢀH]ꢀ.
5.1.4.2. 2-(6-Nitro-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)acetic acid (7b). Yield: 71%, mp: 267–269 °C. 1H NMR
(DMSO-d6) d 4.55 (s, 2H), 8.36 (d, J = 8.4 Hz, 1H), 8.73 (dd,
J = 8.4 Hz 2.1 Hz, 1H), 9.31 (d, J = 2.1 Hz, 1H). MS (ESI) m/z:
285.1[MꢀH]ꢀ.
5.1.2. General procedure for the synthesis of 5 and 9a–9c
5.1.2.1.
(5).
6-Aminobenzo[d]isothiazol-3(2H)-one
To a solution of 4 (6.17 g) in 350 ml THF, 10% Pd/C was
1,1-dioxide
added. Then 4 was reduced by hydrogen at atmospheric pressure
for 4 h and the catalyst was removed by filtration. The filtrate
was evaporated to afford a slightly yellow powder in 95% yield
with no more purification, mp: 263–265 °C.
Compounds 9a–9c were synthesized following the procedure
described above.
5.1.4.3. 3-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)propa-
noic acid (7c). Yield: 67%, mp: 164–166 °C. 1H NMR (DMSO-d6) d
2.71 (t, J = 7.2 Hz, 2H), 3.94 (t, J = 7.2 Hz, 2H), 7.99 (t, J = 7.8 Hz, 1H),
8.05 (t, J = 7.8 Hz, 1H), 8.11 (d, J = 7.8 Hz, 1H), 8.31 (d, J = 7.8 Hz,
1H), 12.53 (s, 1H). MS (ESI) m/z: 254.2 [MꢀH]ꢀ.
5.1.2.2. 3-(6-Amino-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)propanoic acid (9a).
Yield: 88%, mp: 196–199 °C. 1H NMR
5.1.4.4. 3-(6-Nitro-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)propanoic acid (7d). Yield: 73%, mp: 208–210 °C. 1H NMR
(DMSO-d6) d 2.73 (t, J = 7.2 Hz, 2H), 3.98 (t, J = 7.2 Hz, 2H), 8.32
(d, J = 8.4 Hz, 1H), 8.71 (d, J = 7.8 Hz, 1H), 9.28 (s, 1H), 12.55 (s,
1H). MS (ESI) m/z: 299.4 [MꢀH]ꢀ.
(DMSO-d6) d 2.64 (t, J = 7.2 Hz, 2H), 3.82 (t, J = 7.2 Hz, 2H), 6.88 (s,
2H), 6.93 (dd, J = 9.0 Hz 2.4 Hz, 1H), 7.04 (d, J = 1.8 Hz, 1H), 7.67 (d,
J = 8.4 Hz, 1H), 12.49 (s, 1H). 13C NMR (DMSO-d6): 32.97, 34.02,
103.10, 111.38, 117.96, 126.49, 139.59, 155.57, 158.72, 171.60.
HRMS (AP-ESI) m/z Calcd for C10H10N2O5S [M+H]+ 271.0383.
Found: 271.0381.
5.1.4.5. 4-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)buta-
noic acid (7e).
Yield: 73%, mp: 110–112 °C. 1H NMR
5.1.2.3. 5-(6-Amino-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)pentanoic acid (9b).
(DMSO-d6) d 1.90 (m, J = 7.2 Hz 2H), 2.34 (t, J = 7.2 Hz, 2H), 3.74
(t, J = 7.2 Hz, 2H), 7.97 (m, 2H), 8.09 (d, J = 6.9 Hz, 1H), 8.29 (d,
J = 6.9 Hz 0.9 Hz, 1H), 12.14 (s, 1H). MS (ESI) m/z: 268.2 [MꢀH]ꢀ.
Yield: 92%, mp: 117–119 °C. 1H NMR
(DMSO-d6) d 1.53 (m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz, 2H), 2.24
(t, J = 7.2 Hz, 1H), 2.32 (t, J = 7.2 Hz, 1H), 3.59 (t, J = 7.2 Hz, 2H),
6.85 (s, 2H), 6.92 (dd, J = 9.0 Hz 1.8 Hz, 1H), 7.04 (d, J = 1.2 Hz,
1H), 7.67 (d, J = 8.4 Hz, 1H), 12.04 (s, 1H). 13C NMR (DMSO-d6):
21.59, 27.46, 32.77, 37.75, 103.08, 111.44, 117.91, 126.41, 139.56,
155.51, 158.99, 174.15. HRMS (AP-ESI) m/z Calcd for C12H14N2O5S
[M+H]+ 299.0696. Found: 299.0688.
5.1.4.6. 4-(6-Nitro-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)butanoic acid (7f).
Yield: 75%, mp: 164–166 °C. 1H NMR
(DMSO-d6) d 1.94 (m, J = 7.2 Hz, 2H), 2.37 (t, J = 7.2 Hz, 2H), 3.80
(t, J = 7.2 Hz, 2H), 8.31 (d, J = 8.4 Hz, 1H), 8.71 (d, J = 8.4 Hz, 1H),
9.27 (s, 1H), 12.15 (s, 1H). MS (ESI) m/z: 313.3 [MꢀH]ꢀ.
5.1.2.4. 6-(6-Amino-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)hexanoic acid (9c).
(DMSO-d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.49 (m, J = 7.2 Hz, 2H), 1.65
5.1.4.7. 5-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)penta-
noic acid (7g).
d 1.56 (m, J = 7.2 Hz, 2H), 1.73 (m, J = 7.2 Hz, 2H), 2.26 (t, J = 7.2 Hz,
Yield: 89%, mp: 168–170 °C. 1H NMR
Yield: 75%, mp: 86–89 °C. 1H NMR (DMSO-d6)

1534
L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
2H), 3.71 (t, J = 7.2 Hz, 2H), 7.99 (t, J = 7.8 Hz, 1H), 8.04 (t, J = 7.2 Hz,
1H), 8.10 (d, J = 7.8 Hz, 1H), 8.31 (d, J = 7.8 Hz, 1H), 12.06 (s, 1H).
MS (ESI) m/z: 282.4 [MꢀH]ꢀ.
5.1.6.3.
3-(1,1-Dioxido-3-oxo-6-(3,4,5-trimethoxybenzami-
Yield:
do)benzo[d]isothiazol-2(3H)-yl)propanoic acid (10c).
47%, mp: 252–255 °C. 1H NMR (DMSO-d6) d 2.71 (t, J = 7.2 Hz, 2H),
3.75 (s, 3H), 3.89 (s, 6H), 3.93 (t, J = 7.2 Hz, 2H), 7.32 (s, 2H), 8.13 (d,
J = 8.4 Hz, 1H), 8.23 (dd, J = 9.0 Hz 1.8 Hz, 1H), 8.58 (d, J = 1.2 Hz,
1H), 10.86 (s, 1H), 12.53 (s, 1H). MS (ESI) m/z: 463.4 [MꢀH]ꢀ.
5.1.4.8. 5-(6-Nitro-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)pentanoic acid (7h).
Yield: 71%, mp: 151–153 °C. 1H
NMR (DMSO-d6) d 1.57 (m, J = 7.2 Hz, 2H), 1.74 (m, J = 7.2 Hz,
2H), 2.26 (t, J = 7.2 Hz, 2H), 3.75 (t, J = 7.2 Hz, 2H), 8.32 (d,
J = 8.4 Hz, 1H), 8.71 (dd, J = 8.4 Hz 2.4 Hz, 1H), 9.27 (d, J = 1.8 Hz,
1H), 12.06 (s, 1H). MS (ESI) m/z: 327.3 [MꢀH]ꢀ.
5.1.6.4. 5-(6-Benzamido-1,1-dioxido-3-oxobenzo[d]isothiazol-
2(3H)-yl)pentanoic acid (10d).
Yield: 67%, mp: 162–165 °C.
1H NMR (DMSO-d6) d 1.54 (m, J = 7.2 Hz, 2H), 1.71 (m, J = 7.2 Hz,
2H), 2.25 (t, J = 7.2 Hz, 2H), 3.69 (t, J = 7.2 Hz, 2H), 7.56 (t,
J = 7.5 Hz, 2H), 7.64 (t, J = 7.2 Hz, 1H), 7.99 (d, J = 7.8 Hz, 2H), 8.10
(d, J = 8.4 Hz, 1H), 8.23 (dd, J = 8.7 Hz 1.8 Hz, 1H), 8.64 (d,
J = 1.8 Hz, 1H), 11.02 (s, 1H), 12.04 (s, 1H). MS (ESI) m/z: 401.3
[MꢀH]ꢀ.
5.1.5. General procedure for the synthesis of 7i–7k
Saccharin, 4 or 6 (13.2 mmol) and sodium bicarbonate (1.1 g,
13.2 mmol) were added to 5 ml of DMF. 6-Bromohexanoic acid
(14.0 mmol) was added slowly and the resulting solution was stir-
red for 4 h at 60–80 °C. The mixture was poured into 25 ml water
to give the crude product. It can be recrystallized from ethanol or
water to give pure product.
5.1.6.5. 6-(6-Benzamido-1,1-dioxido-3-oxobenzo[d]isothiazol-
2(3H)-yl)hexanoic acid (10e).
Yield: 67%, mp: 147–150 °C.
1H NMR (DMSO-d6) d 1.34 (m, J = 7.2 Hz, 2H), 1.52 (m, J = 7.2 Hz,
2H), 1.71 (m, J = 7.2 Hz, 2H), 2.21 (t, J = 7.2 Hz, 2H), 3.69 (t,
J = 7.2 Hz, 2H), 7.58 (t, J = 7.2 Hz, 2H), 7.65 (t, J = 7.2 Hz, 1H), 8.01
(d, J = 7.8 Hz, 2H), 8.10 (d, J = 8.4 Hz, 1H), 8.26 (d, J = 8.4 Hz, 1H),
8.67 (s, 1H), 11.08 (s, 1H), 12.02 (s, 1H). MS (ESI) m/z: 415.4
[MꢀH]ꢀ.
5.1.5.1. 6-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)hexa-
noic acid (7i).
1.35(m, J = 7.2 Hz, 2H), 1.51 (m, J = 7.2 Hz, 2H), 1.71 (m,
Yield: 81%, mp: 83–85 °C. 1H NMR (DMSO-d6)
d
J = 7.2 Hz, 2H), 2.19 (t, J = 7.2 Hz, 2H), 3.69 (t, J = 7.2 Hz, 2H), 7.99
(t, J = 7.2 Hz, 1H), 8.04 (t, J = 7.2 Hz, 1H), 8.10 (d, J = 7.2 Hz, 1H),
8.30 (d, J = 7.2 Hz, 1H), 12.00 (s, 1H). MS (ESI) m/z: 296.4 [MꢀH]ꢀ.
5.1.6.6. 6-(6-([1,10-Biphenyl]-4-ylcarboxamido)-1,1-dioxido-3-
5.1.5.2. 6-(6-Nitro-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)hexanoic acid (7j).
(DMSO-d6) d 1.36 (m, J = 7.2 Hz, 2H), 1.52 (m, J = 7.2 Hz, 2H), 1.74
(m, J = 7.2 Hz, 2H), 2.20 (t, J = 7.2 Hz, 2H), 3.74 (t, J = 7.2 Hz, 2H),
8.31 (d, J = 8.4 Hz, 1H), 8.71 (dd, J = 7.8 Hz 1.8 Hz, 1H), 9.27 (s,
1H), 12.01 (s, 1H). MS (ESI) m/z: 341.3 [MꢀH]ꢀ.
oxobenzo[d]isothiazol-2(3H)-yl)hexanoic acid (10f).
Yield:
Yield: 87%, mp: 165–167 °C. 1H NMR
42%, mp: 205–207 °C. 1H NMR (DMSO-d6) d 1.36 (m, J = 7.2 Hz,
2H), 1.53 (m, J = 7.2 Hz, 2H), 1.71 (m, J = 7.2 Hz, 2H), 2.20 (t,
J = 7.2 Hz, 2H), 3.69 (t, J = 7.2 Hz, 2H), 7.44 (t, J = 7.2 Hz, 1H), 7.52
(t, J = 7.2 Hz, 2H), 7.78 (d, J = 7.8 Hz, 2H), 7.90 (d, J = 7.8 Hz, 2H),
8.11 (d, J = 8.4 Hz, 2H), 8.12 (d, J = 8.4 Hz, 1H), 8.26 (d, J = 9.0 Hz,
1H), 8.67 (s, 1H), 11.07 (s, 1H), 12.03 (s, 1H). MS (ESI) m/z: 491.4
[MꢀH]ꢀ.
5.1.5.3. 6-(6-Iodo-1,1-dioxido-3-oxobenzo[d]isothiazol-2(3H)-
yl)hexanoic acid (7k).
Yield: 84%, mp: 153–155 °C. 1H NMR
(DMSO-d6) d 1.32 (m, J = 7.2 Hz, 2H), 1.49 (m, J = 7.2 Hz, 2H), 1.69
(m, J = 7.2 Hz, 2H), 2.19 (t, J = 7.2 Hz, 2H), 3.98 (t, J = 7.2 Hz, 2H),
7.81 (d, J = 7.2 Hz, 1H), 8.35 (d, J = 7.8 Hz, 1H), 8.82 (s, 1H), 12.01
(s, 1H). MS (ESI) m/z: 422.2 [MꢀH]ꢀ.
5.1.6.7.
6-(1,1-Dioxido-3-oxo-6-(3,4,5-trimethoxybenzamido)
benzo[d]isothiazol-2(3H)-yl)hexanoic acid (10g). Yield: 57%,
mp: 202–204 °C. 1H NMR (DMSO-d6) d 1.35 (m, J = 7.2 Hz, 2H),
1.53 (m, J = 7.2 Hz, 2H), 1.72 (m, J = 7.2 Hz, 2H), 2.20 (t, J = 7.2 Hz,
2H), 3.69 (t, J = 7.2 Hz, 2H), 3.75 (s, 3H), 3.89 (s, 6H), 7.32 (s, 2H),
8.13 (d, J = 8.4 Hz, 1H), 8.23 (dd, J = 9.0 Hz 1.8 Hz, 1H), 8.59 (d,
J = 1.2 Hz, 1H), 10.86 (s, 1H), 12.01 (s, 1H). MS (ESI) m/z: 505.4
[MꢀH]ꢀ.
5.1.6. General procedure for the synthesis of 10a–10p
The carboxylic acid (6.5 mmol) was dissolved in excess thionyl
chloride (10 ml) and two drops of DMF. The mixture was kept 60 °C
for 2 h and excess thionyl chloride was evaporated. The freshly
prepared acyl chloride was then dissolved in 15 ml of THF and
the resulting solution was added to the mixture of 9a, 9b or 9c
(5.5 mmol) and sodium bicarbonate (13.5 mmol).The resulting
mixture was stirred for 8 h at room temperature. After removing
the solvent, the mixture was acidified with 1 M HCl and the final
product was purified by recrystallization in water/ethanol.
5.1.6.8.
6-(6-(4-Iodobenzamido)-1,1-dioxido-3-oxobenzo[d]
isothiazol-2(3H)-yl)hexanoic acid (10h). Yield: 77%, mp: 209–
211 °C. 1H NMR (DMSO-d6) d 1.34 (m, J = 7.2 Hz, 2H), 1.52 (m,
J = 7.2 Hz, 2H), 1.71 (m, J = 7.2 Hz, 2H), 2.20 (t, J = 7.2 Hz, 2H),
3.68 (t, J = 7.2 Hz, 2H), 7.78 (d, J = 8.4 Hz, 2H), 7.98 (d, J = 8.4 Hz,
2H), 8.10 (d, J = 8.4 Hz, 1H), 8.21 (d, J = 8.4 Hz, 1H), 8.62 (s, 1H),
11.04 (s, 1H), 12.01 (s, 1H). MS (ESI) m/z: 541.3 [MꢀH]ꢀ.
5.1.6.1. 3-(6-Benzamido-1,1-dioxido-3-oxobenzo[d]isothiazol-
2(3H)-yl)propanoic acid (10a).
Yield: 75%, mp: 182–185 °C.
5.1.6.9. 6-(6-(4-Methoxybenzamido)-1,1-dioxido-3-oxobenzo[d]
isothiazol-2(3H)-yl)hexanoic acid (10i). Yield: 74%, mp: 135–
138 °C. 1H NMR (DMSO-d6) d 1.34 (m, J = 7.2 Hz, 2H), 1.52 (m,
J = 7.2 Hz, 2H), 1.71 (m, J = 7.2 Hz, 2H), 2.20 (t, J = 7.2 Hz, 2H),
3.68 (t, J = 7.2 Hz, 2H), 3.83 (s, 3H), 7.11 (d, J = 8.4 Hz, 2H), 8.01
(d, J = 8.4 Hz, 2H), 8.08 (d, J = 9.0 Hz, 1H), 8.22 (dd, J = 8.4 Hz
1.8 Hz, 1H), 8.64 (d, J = 1.2 Hz, 1H), 10.85 (s, 1H), 12.07 (s, 1H).
MS (ESI) m/z: 445.5 [MꢀH]ꢀ.
1H NMR (DMSO-d6) d 2.71 (t, J = 7.2 Hz, 2H), 3.93 (t, J = 7.2 Hz, 2H),
7.58 (t, J = 7.8 Hz, 2H), 7.65 (t, J = 7.2 Hz, 1H), 8.00 (d, J = 7.2 Hz,
2H), 8.12 (d, J = 8.4 Hz, 1H), 8.24 (d, J = 8.4 Hz, 1H), 8.65 (s, 1H),
11.04 (s, 1H), 12.54 (s, 1H). MS (ESI) m/z: 373.2 [MꢀH]ꢀ.
5.1.6.2. 3-(6-([1,10-Biphenyl]-4-ylcarboxamido)-1,1-dioxido-3-
oxobenzo[d]isothiazol-2(3H)-yl)propanoic acid (10b). Yield:
55%, mp: 267–269 °C. 1H NMR (DMSO-d6) d 2.72 (t, J = 7.2 Hz, 2H),
3.95 (t, J = 7.2 Hz, 2H), 7.45 (t, J = 7.2 Hz, 1H), 7.52 (t, J = 7.8 Hz,
2H), 7.78 (d, J = 7.2 Hz, 2H), 7.90 (d, J = 8.4 Hz, 2H), 8.11 (d,
J = 9.0 Hz, 2H), 8.13 (d, J = 8.4 Hz, 1H), 8.26 (dd, J = 8.4 Hz 1.2 Hz,
1H), 8.67 (d, J = 1.2 Hz, 1H), 11.08 (s, 1H), 12.54 (s, 1H). MS (ESI) m/
z: 449.4 [MꢀH]ꢀ.
5.1.6.10. 6-(1,1-Dioxido-3-oxo-6-(2-phenylacetamido)benzo[d]
isothiazol-2(3H)-yl)hexanoic acid (10j). Yield: 67%, mp: 98–
100 °C. 1H NMR (DMSO-d6) d 1.32 (m, J = 7.2 Hz, 2H), 1.48 (m,
J = 7.2 Hz, 2H), 1.66 (m, J = 7.2 Hz, 2H), 2.18 (t, J = 7.2 Hz, 2H),
3.65 (t, J = 7.2 Hz, 2H), 3.76 (s, 2H), 7.24 (m, 5H), 7.92 (dd,

L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
1535
J = 8.7 Hz 1.8 Hz, 1H), 8.04 (d, J = 8.4 Hz, 1H), 8.48 (d, J = 1.8 Hz, 1H),
11.03 (s, 1H), 11.98 (s, 1H). MS (ESI) m/z: 429.5 [MꢀH]ꢀ.
and saturated sodium bicarbonate (50 ml) three times, respec-
tively. The cured product can be purified by recrystallization with
ethyl acetate or column chromatography (dichloromethane/meth-
anol, 100:1).
5.1.6.11. 6-(6-(3-Bromobenzamido)-1,1-dioxido-3-oxobenzo[d]
isothiazol-2(3H)-yl)hexanoic acid (10k).
Yield: 75%, mp:
142–144 °C. 1H NMR (DMSO-d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.50
(m, J = 7.2 Hz, 2H), 1.69 (m, J = 7.2 Hz, 2H), 2.19 (t, J = 7.2 Hz, 2H),
3.67 (t, J = 7.2 Hz, 2H), 7.53 (t, J = 8.1 Hz, 1H), 7.85 (m, J = 8.1 Hz
1.2 Hz, 1H), 7.98 (dt, J = 8.4 Hz 1.2 Hz, 1H), 8.11 (d, J = 8.4 Hz,
1H), 8.19 (t, J = 1.8 Hz, 1H), 8.21 (dd, J = 8.4 Hz 1.8 Hz, 1H), 8.60
(d, J = 1.8 Hz, 1H), 11.08 (s, 1H), 11.99 (s, 1H). MS (ESI) m/z:
493.3/495.2 [MꢀH]ꢀ.
5.1.7.1.
hydroxyacetamide (8a). Yield: 42%, mp: 172–174 °C. 1H NMR
(DMSO-d6) 4.26 (s, 2H), 8.01 (t, J = 7.2 Hz, 1H), 8.07 (t,
J = 7.2 Hz, 1H), 8.13 (d, J = 7.2 Hz, 1H), 8.33 (d, J = 7.2 Hz, 1H),
9.08 (s, 1H), 10.83 (s, 1H). 13C NMR (DMSO-d6): 37.99, 121.60,
125.05, 126.48, 135.26, 135.79, 136.73, 158.54, 161.83. HRMS
(AP-ESI) m/z Calcd for C9H8N2O5S [M+H]+ 257.0227. Found:
257.0220.
2-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)-N-
d
5.1.6.12. 6-(6-(2-Naphthamido)-1,1-dioxido-3-oxobenzo[d]isot-
hiazol-2(3H)-yl)hexanoic acid (10l).
Yield: 65%, mp: 156–
5.1.7.2. N-Hydroxy-2-(6-nitro-1,1-dioxido-3-oxobenzo[d]isot-
159 °C. 1H NMR (DMSO-d6) d 1.32 (m, J = 7.2 Hz, 2H), 1.51 (m,
J = 7.2 Hz, 2H), 1.70 (m, J = 7.2 Hz, 2H), 2.18 (t, J = 7.2 Hz, 2H),
3.68 (t, J = 7.2 Hz, 2H), 7.64 (m, 2H), 8.03 (m, 5H), 8.28 (dd,
J = 8.4 Hz 1.5 Hz, 1H), 8.66 (s, 1H), 8.68 (d, J = 1.8 Hz, 1H), 11.20
(s, 1H), 12.00 (s, 1H). MS (ESI) m/z: 465.5 [MꢀH]ꢀ.
hiazol-2(3H)-yl)acetamide (8b).
Yield: 31%, mp: 156–
159 °C. 1H NMR (DMSO-d6) d 3.89 (s, 2H), 8.36 (d, J = 8.4 Hz, 1H),
8.73 (d, J = 8.4 Hz, 1H), 9.12 (s, 1H), 9.30 (s, 1H), 10.86 (s, 1H).
13C NMR (DMSO-d6): 38.54, 118.16, 126.73, 130.32, 131.03,
137.66, 151.85, 157.01, 161.45. HRMS (AP-ESI) m/z Calcd for C9H7-
N3O7S [M+H]+ 302.0077. Found: 302.0071.
5.1.6.13.
6-(1,1-Dioxido-3-oxo-6-(thiophene-2-carboxamido)
Yield:
benzo[d]isothiazol-2(3H)-yl)hexanoic acid (10m).
5.1.7.3.
hydroxypropanamide (8c).
3-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)-N-
Yield: 27%, mp: 180–182 °C. 1H
67%, mp: 201–203 °C. 1H NMR (DMSO-d6) d 1.31 (m, J = 7.2 Hz,
2H), 1.47 (m, J = 7.2 Hz, 2H), 1.68 (m, J = 7.2 Hz, 2H), 2.19 (t,
J = 7.2 Hz, 2H), 3.67 (t, J = 7.2 Hz, 2H), 7.28 (m, 1H), 7.97 (dd,
J = 5.1 Hz 0.9 Hz, 1H), 8.10 (m, 2H), 8.18 (dd, J = 8.4 Hz 1.8 Hz,
1H), 8.58 (d, J = 1.8 Hz, 1H), 10.96 (s, 1H), 12.00 (s, 1H). MS (ESI)
m/z: 421.3 [MꢀH]ꢀ.
NMR (DMSO-d6) d 2.47 (t, J = 7.2 Hz, 2H), 3.90 (t, J = 7.2 Hz, 2H),
7.99 (t, J = 7.2 Hz, 1H), 8.05 (t, J = 7.8 Hz, 1H), 8.11 (d, J = 7.2 Hz,
1H), 8.31 (d, J = 7.8 Hz, 1H), 8.85 (s, 1H), 10.57 (s, 1H). 13C NMR
(DMSO-d6): 31.07, 34.86, 121.41, 125.02, 126.22, 135.25, 135.77,
136.62, 158.28, 165.81. HRMS (AP-ESI) m/z Calcd for C10H10N2O5S
[M+H]+ 271.0383. Found: 271.0382.
5.1.6.14.
(E)-6-(1,1-Dioxido-3-oxo-6-(3-(p-tolyl)acrylamido)
Yield:
benzo[d]isothiazol-2(3H)-yl)hexanoic acid (10n).
5.1.7.4. N-Hydroxy-3-(6-nitro-1,1-dioxido-3-oxobenzo[d]isot-
75%, mp: 249–251 °C. 1H NMR (DMSO-d6) d 1.32 (m, J = 7.2 Hz,
2H), 1.49 (m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz, 2H), 2.18 (t,
J = 7.2 Hz, 2H), 2.35 (s, 3H), 3.66 (t, J = 7.2 Hz, 2H), 6.76 (d,
J = 15.9 Hz, 1H), 7.27 (d, J = 7.8 Hz, 2H), 7.56 (d, J = 7.5 Hz, 2H),
7.65 (d, J = 15.6 Hz, 1H), 7.96 (d, J = 8.7 Hz, 1H), 8.06 (d, J = 8.7 Hz,
1H), 8.61 (d, J = 1.5 Hz, 1H), 11.04 (s, 1H), 12.01 (s, 1H). MS (ESI)
m/z: 455.4 [MꢀH]ꢀ.
hiazol-2(3H)-yl)propanamide (8d).
Yield: 23% yield, mp:
191–193 °C. 1H NMR (DMSO-d6) d 2.49 (t, J = 7.2 Hz, 2H), 3.95 (t,
J = 7.2 Hz, 2H), 8.32 (d, J = 8.4 Hz, 1H), 8.71 (dd, J = 8.4 Hz 1.8 Hz,
1H), 8.85 (s, 1H), 9.28 (s, 1H), 10.58 (s, 1H). 13C NMR (DMSO-d6):
30.93, 35.42, 117.98, 126.73, 130.25, 130.97, 137.59, 151.78,
156.73, 165.56. HRMS (AP-ESI) m/z Calcd for C10H9N3O7S [M+H]+
316.0234. Found: 316.0228.
5.1.6.15.
6-(6-(4-Fluorobenzamido)-1,1-dioxido-3-oxobenzo
5.1.7.5.
4-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)-N-
[d]isothiazol-2(3H)-yl)hexanoic acid (10o). Yield: 73%, mp:
186–188 °C. 1H NMR (DMSO-d6) d 1.29 (m, J = 7.2 Hz, 2H), 1.47
(m, J = 7.2 Hz, 2H), 1.68 (m, J = 7.2 Hz, 2H), 2.19 (t, J = 7.2 Hz, 2H),
3.67 (t, J = 7.2 Hz, 2H), 7.41 (t, J = 9.0 Hz, 2H), 8.07 (m, 3H), 8.20
(dd, J = 8.7 Hz 1.8 Hz, 1H), 8.62 (d, J = 1.8 Hz, 1H), 11.03 (s, 1H),
12.01 (s, 1H). MS (ESI) m/z: 433.4 [MꢀH]ꢀ.
hydroxybutanamide (8e). Yield: 33%, mp: 106–108 °C. 1H
NMR (DMSO-d6) d 1.94 (m, J = 7.2 Hz, 2H), 2.09 (t, J = 7.2 Hz, 2H),
3.73 (t, J = 7.2 Hz, 2H), 8.00 (t, J = 7.2 Hz, 1H), 8.05 (t, J = 7.2 Hz,
1H), 8.11 (d, J = 7.8 Hz, 1H), 8.31 (d, J = 7.8 Hz, 1H), 8.78 (s, 1H),
10.42 (s, 1H). 13C NMR (DMSO-d6): 24.12, 29.36, 38.26, 121.45,
125.01, 126.32, 135.19, 135.70, 136.69, 158.51, 168.15. HRMS
(AP-ESI) m/z Calcd for C11H12N2O5S [M+H]+ 285.0540. Found:
285.0531.
5.1.6.16.
6-(6-(4-Nitrobenzamido)-1,1-dioxido-3-oxobenzo
[d]isothiazol-2(3H)-yl)hexanoic acid (10p). Yield: 71%, mp:
218–220 °C. 1H NMR (DMSO-d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.50
(m, J = 7.2 Hz, 2H), 1.69 (m, J = 7.2 Hz, 2H), 2.19 (t, J = 7.2 Hz, 2H),
3.68 (t, J = 7.2 Hz, 2H), 8.13 (d, J = 8.4 Hz, 1H), 8.21 (m, 3H), 8.41
(d, J = 8.7 Hz, 2H), 8.63 (d, J = 1.5 Hz, 1H), 11.32 (s, 1H), 12.02 (s,
1H). MS (ESI) m/z: 460.5 [MꢀH]ꢀ.
5.1.7.6. N-Hydroxy-4-(6-nitro-1,1-dioxido-3-oxobenzo[d]isot-
hiazol-2(3H)-yl)butanamide (8f). Yield: 53%, mp: 156–158 °C.
1H NMR (DMSO-d6) d 1.95 (m, J = 7.2 Hz, 2H), 2.09 (t, J = 7.2 Hz,
2H), 3.77 (t, J = 7.2 Hz, 2H), 8.32 (d, J = 8.4 Hz, 1H), 8.71 (dd,
J = 8.4 Hz 1.8 Hz, 1H), 9.03 (s, 1H), 9.28 (d, J = 1.2 Hz, 1H), 10.39
(s, 1H). 13C NMR (DMSO-d6): 23.99, 29.29, 38.82, 117.92, 126.73,
130.21, 131.03, 137.57, 151.75, 156.98, 168.11. HRMS (AP-ESI) m/
z Calcd for C11H11N3O7S [M+H]+ 330.0390. Found: 330.0380.
5.1.7. General procedure for the synthesis of 8a–8k and 11a–1p
To a solution of the corresponding acid (3.3 mmol) in anhydrous
THF (20 ml) was added Et3N (0.33 ml, 3.3 mmol) and Isobutyl chlo-
roformate (0.43 ml, 3.3 mmol) sequentially. The resulting solution
was stirred for 10 min at 0 °C. A solution of NH2OH.HCl (0.34 g,
5.0 mmol) and Et3N (0.53 ml, 5.0 mmol) in anhydrous CH3OH
(1 ml) was added to the above mixture. The resulting solution
was then stirred for 3–6 h at room temperature. After filtering
the mixture, removing the solvents, the resulting residue was
dissolved in ethyl acetate (50 ml), washed with HCl (1 M, 55 ml)
5.1.7.7.
hydroxypentanamide (8g).
5-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)-N-
Yield: 35%, mp: 103–105 °C. 1H
NMR (DMSO-d6) d 1.56 (m, J = 7.2 Hz, 2H), 1.68 (m, J = 7.2 Hz,
2H), 1.99 (t, J = 7.2 Hz, 2H), 3.70 (t, J = 7.2 Hz, 2H), 7.99 (t,
J = 7.8 Hz, 1H), 8.04 (t, J = 7.8 Hz, 1H), 8.10 (d, J = 7.2 Hz, 1H), 8.31
(d, J = 7.8 Hz, 1H), 8.70 (s, 1H), 10.37 (s, 1H). 13C NMR (DMSO-
d6): 22.38, 27.47, 31.65, 38.39, 121.43, 124.98, 126.25, 135.18,

1536
L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
135.70, 136.70, 158.52, 168.69. HRMS (AP-ESI) m/z Calcd for C12-
(AP-ESI) m/z Calcd for C23H19N3O6S [M+H]+ 466.1067. Found:
466.1070.
H14N2O5S [M+H]+ 299.0696. Found: 299.0699.
5.1.7.8. N-Hydroxy-5-(6-nitro-1,1-dioxido-3-oxobenzo[d]isot-
5.1.7.14. N-(2-(3-(Hydroxyamino)-3-oxopropyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-3,4,5-trimethoxyben-
zamide (11c). Yield: 43%, mp: 220–222 °C. 1H NMR (DMSO-d6) d
2.48 (t, J = 7.2 Hz, 2H), 3.76 (s, 3H), 3.89 (s, 6H), 3.92 (t, J = 7.2 Hz,
2H), 7.32 (s, 2H), 8.13 (d, J = 9.0 Hz, 1H), 8.23 (d, J = 8.4 Hz, 1H),
8.60 (s, 1H), 8.86 (s, 1H), 10.59 (s, 1H), 10.87 (s, 1H). 13C NMR
(DMSO-d6): 31.19, 34.92, 56.12, 60.13, 105.60, 110.98, 120.31,
125.29, 126.10, 128.82, 137.87, 140.94, 145.61, 152.68, 157.97,
165.69, 165.78. HRMS (AP-ESI) m/z Calcd for C20H21N3O9S [M+H]+
480.1071. Found: 480.1061.
hiazol-2(3H)-yl)pentanamide (8h).
Yield: 31%, mp: 157–
159 °C. 1H NMR (DMSO-d6) d 1.57 (m, J = 7.2 Hz, 2H), 1.70 (m,
J = 7.2 Hz, 2H), 1.99 (t, J = 7.2 Hz, 2H), 3.74 (t, J = 7.2 Hz, 2H), 8.31
(d, J = 8.4 Hz, 1H), 8.70 (s, 1H), 8.71 (dd, J = 8.4 Hz 1.8 Hz, 1H),
9.27 (d, J = 1.2 Hz, 1H), 10.37 (s, 1H). 13C NMR (DMSO-d6): 22.33,
27.35, 31.62, 38.99, 117.91, 126.74, 130.22, 130.94, 137.59,
151.75, 157.00, 168.64. HRMS (AP-ESI) m/z Calcd for C12H13N3O7S
[M+H]+ 344.0547. Found: 344.0552.
5.1.7.9.
hydroxyhexanamide (8i).
6-(1,1-Dioxido-3-oxobenzo[d]isothiazol-2(3H)-yl)-N-
Yield: 32%, mp: 139–141 °C. 1H
5.1.7.15. N-(2-(5-(Hydroxyamino)-5-oxopentyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)benzamide
NMR (DMSO-d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.50 (m, J = 7.2 Hz,
2H), 1.70 (m, J = 7.2 Hz, 2H), 1.93 (t, J = 7.2 Hz, 2H), 3.69 (t,
J = 7.2 Hz, 2H), 7.99 (t, J = 7.2 Hz, 1H), 8.04 (t, J = 7.2 Hz, 1H), 8.10
(d, J = 7.8 Hz, 1H), 8.30 (d, J = 7.8 Hz, 1H), 8.67 (s, 1H), 10.34 (s,
1H). 13C NMR (DMSO-d6): 24.56, 25.66, 27.61, 32.02, 38.52,
121.42, 125.00, 126.27, 135.19, 135.70, 136.72, 158.51, 168.92.
HRMS (AP-ESI) m/z Calcd for C13H16N2O5S [M+H]+ 313.0853.
Found: 313.0858.
(11d). Yield: 53%, mp: 207–209 °C. 1H NMR (DMSO-d6) d 1.53
(m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz, 2H), 1.98 (t, J = 7.2 Hz, 2H),
3.68 (t, J = 7.2 Hz, 2H), 7.56 (t, J = 7.5 Hz, 2H), 7.64 (t, J = 7.2 Hz,
1H), 7.99 (d, J = 7.2 Hz, 2H), 8.10 (d, J = 8.4 Hz, 1H), 8.22 (dd,
J = 8.7 Hz 1.2 Hz, 1H), 8.65 (d, J = 1.5 Hz, 1H), 8.68 (d, J = 1.5 Hz,
1H), 10.36 (s, 1H), 11.02 (s, 1H). 13C NMR (DMSO-d6): 22.39,
27.56, 31.66, 38.42, 110.76, 120.32, 125.19, 126.10, 127.92,
128.54, 132.36, 133.80, 137.91, 145.67, 158.26, 166.47, 168.69.
HRMS (AP-ESI) m/z Calcd for C19H19N3O6S [M+H]+ 418.1067.
Found: 418.1076.
5.1.7.10. N-Hydroxy-6-(6-nitro-1,1-dioxido-3-oxobenzo[d]isot-
hiazol-2(3H)-yl)hexanamide (8j).
Yield: 27%, mp: 158–
160 °C. 1H NMR (DMSO-d6) d 1.33 (m, J = 7.2 Hz, 2H), 1.51 (m,
J = 7.2 Hz, 2H), 1.73 (m, J = 7.2 Hz, 2H),1.94 (t, J = 7.2 Hz, 2H), 3.73
(t, J = 7.2 Hz, 2H), 8.31 (d, J = 8.4 Hz, 1H), 8.67 (s, 1H), 8.71 (dd,
J = 8.4 Hz 1.2 Hz, 1H), 9.27 (d, J = 1.8 Hz, 1H), 10.34 (s, 1H). 13C
NMR (DMSO-d6): 24.54, 25.64, 27.50, 32.00, 38.62, 117.89,
126.74, 130.21, 130.94, 137.60, 151.75, 156.98, 168.90. HRMS
(AP-ESI) m/z Calcd for C13H15N3O7S [M+H]+ 358.0703. Found:
358.0695.
5.1.7.16.
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)benzamide
(11e). Yield: 47%, mp: 188–190 °C. 1H NMR (DMSO-d6) d 1.31 (m,
J = 7.2 Hz, 2H), 1.51 (m, J = 7.2 Hz, 2H), 1.70 (m, J = 7.2 Hz, 2H), 1.94
(t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 7.58 (t, J = 7.2 Hz, 2H), 7.65
(t, J = 7.2 Hz, 1H), 8.00 (d, J = 7.2 Hz, 2H), 8.11 (d, J = 8.4 Hz, 1H),
8.23 (d, J = 8.4 Hz, 1H), 8.65 (s, 1H), 8.67 (s, 1H), 10.34 (s, 1H),
11.04 (s, 1H). 13C NMR (DMSO-d6): 24.56, 25.67, 27.70, 32.03,
38.56, 110.77, 120.34, 125.22, 126.14, 127.93, 128.57, 132.38,
133.82, 137.93, 145.67, 158.26, 166.49, 168.90. HRMS (AP-ESI) m/
z Calcd for C20H21N3O6S [M+H]+ 432.1224. Found: 432.1228.
5.1.7.11. N-Hydroxy-6-(6-iodo-1,1-dioxido-3-oxobenzo[d]isot-
hiazol-2(3H)-yl)hexanamide (8k).
Yield: 34%, mp: 122–
124 °C. 1H NMR (DMSO-d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.51 (m,
J = 7.2 Hz, 2H), 1.69 (m, J = 7.2 Hz, 2H), 1.93 (t, J = 7.2 Hz, 2H),
3.67 (t, J = 7.2 Hz, 2H), 7.81 (d, J = 7.2 Hz, 1H), 8.35 (d, J = 7.8 Hz,
1H), 8.66 (s, 1H), 8.82 (s, 1H), 10.33 (s, 1H). 13C NMR (DMSO-d6):
24.54, 25.64, 27.56, 32.01, 38.64, 103.79, 125.70, 126.25, 129.82,
137.76, 143.99, 158.20, 168.89. HRMS (AP-ESI) m/z Calcd for
5.1.7.17.
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-[1,10-biphenyl]-4-car-
boxamide (11f). Yield: 52%, mp: 234–236 °C. 1H NMR (DMSO-
d6) d 1.32 (m, J = 7.2 Hz, 2H), 1.52 (m, J = 7.2 Hz, 2H), 1.71 (m,
J = 7.2 Hz, 2H), 1.95 (t, J = 7.2 Hz, 2H), 3.69 (t, J = 7.2 Hz, 2H), 7.44
(t, J = 7.2 Hz, 1H), 7.52 (t, J = 7.2 Hz, 2H), 7.78 (d, J = 7.2 Hz, 2H),
7.90 (d, J = 7.8 Hz, 2H), 8.11 (d, J = 8.4 Hz, 2H), 8.12 (d, J = 8.4 Hz,
1H), 8.26 (d, J = 8.4 Hz, 1H), 8.68 (s, 1H), 8.69 (s, 1H), 10.36 (s,
1H), 11.07 (s, 1H). 13C NMR (DMSO-d6): 24.57, 25.68, 27.71,
32.04, 38.56, 110.78, 120.32, 125.21, 126.13, 126.72, 126.94,
128.30, 128.65, 129.05, 132.47, 137.93, 138.84, 143.86, 145.69,
158.26, 166.06, 168.91. HRMS (AP-ESI) m/z Calcd for C26H25N3O6S
[M+H]+ 508.1537. Found: 508.1537.
C
13H15IN2O5S [M+H]+ 438.9819. Found: 438.9824.
5.1.7.12. N-(2-(3-(Hydroxyamino)-3-oxopropyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)benzamide
(11a).
Yield: 25%, mp: 239–241 °C. 1H NMR (DMSO-d6) d 2.48
(t, J = 7.2 Hz, 2H), 3.90 (t, J = 7.2 Hz, 2H), 7.58 (t, J = 7.2 Hz, 2H), 7.66
(t, J = 7.2 Hz, 1H), 8.00 (d, J = 7.2 Hz, 2H), 8.12 (d, J = 8.4 Hz, 1H),
8.24 (d, J = 9.0 Hz, 1H), 8.65 (s, 1H), 8.86 (s, 1H), 10.59 (s, 1H),
11.05 (s, 1H). 13C NMR (DMSO-d6): 31.36, 35.10, 110.96, 120.52,
125.41, 126.33, 128.10, 128.73, 132.55, 133.97, 138.09, 145.87,
158.14, 165.84, 166.66. HRMS (AP-ESI) m/z Calcd for C17H15N3O6S
[M+H]+ 390.0754. Found: 390.0762.
5.1.7.18.
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-3,4,5-trimethoxyben-
zamide (11g).
Yield: 47%, mp: 148–150 °C. 1H NMR (DMSO-
d6) d 1.31 (m, J = 7.2 Hz, 2H), 1.51 (m, J = 7.2 Hz, 2H), 1.70 (m,
J = 7.2 Hz, 2H), 1.94 (t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 3.75
(s, 3H), 3.89 (s, 6H), 7.32 (s, 2H), 8.12 (d, J = = 8.4 Hz, 1H), 8.23
(dd, J = 9.0 Hz 1.8 Hz, 1H), 8.59 (d, J = 1.2 Hz, 1H), 8.68 (s, 1H),
10.35 (s, 1H), 10.87 (s, 1H). 13C NMR (DMSO-d6): 24.56, 25.68,
27.70, 32.02, 38.56, 56.14, 60.14, 105.61, 110.97, 120.33, 125.30,
126.13, 128.86, 137.90, 140.95, 145.59, 152.69, 158.26, 165.80,
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
5.1.7.13. N-(2-(3-(Hydroxyamino)-3-oxopropyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-[1,10-biphenyl]-4-car-
boxamide (11b). Yield: 53%, mp: 230–232 °C. 1H NMR (DMSO-
d6) d 2.49 (t, J = 7.2 Hz, 2H), 3.91 (t, J = 7.2 Hz, 2H), 7.44 (t,
J = 7.2 Hz, 1H), 7.52 (t, J = 7.8 Hz, 2H), 7.78 (d, J = 7.2 Hz, 2H), 7.90
(d, J = 7.8 Hz, 2H), 8.11 (d, J = 7.8 Hz, 2H), 8.12 (d, J = 7.8 Hz, 1H),
8.27 (d, J = 8.4 Hz, 1H), 8.69 (s, 1H), 8.88 (s, 1H), 10.60 (s, 1H),
11.08 (s, 1H). 13C NMR (DMSO-d6): 31.21, 34.93, 110.79, 120.31,
125.22, 126.12, 126.70, 126.93, 128.29, 128.66, 129.04, 132.44,
137.91, 138.82, 143.85, 145.73, 157.97, 165.69, 166.06. HRMS
168.90. HRMS (AP-ESI) m/z Calcd for
522.1541. Found: 522.1538.
C
23H27N3O9S [M+H]+

L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
1537
5.1.7.19.
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-4-iodobenzamide
(11h).
Yield: 47%, mp: 193–195 °C. 1H NMR (DMSO-d6) d 1.30
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
5.1.7.24.
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)thiophene-2-carbox-
amide (11m). Yield: 49%, mp: 194–196 °C. 1H NMR (DMSO-d6) d
1.28 (m, J = 7.2 Hz, 2H), 1.48 (m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz,
2H), 1.91 (t, J = 7.2 Hz, 2H), 3.67 (t, J = 7.2 Hz, 2H), 7.28 (m, 1H),
7.97 (dd, J = 4.8 Hz 0.9 Hz, 1H), 8.10 (m, 2H), 8.18 (dd, J = 8.4 Hz
1.8 Hz, 1H), 8.59 (d, J = 1.5 Hz, 1H), 8.67 (s, 1H), 10.35 (s, 1H),
10.98 (s, 1H). 13C NMR (DMSO-d6): 24.56, 25.66, 27.69, 32.02,
38.54, 110.74, 120.32, 125.12, 126.17, 128.34, 130.55, 133.42,
137.90, 138.52, 145.30, 158.23, 160.62, 168.91. HRMS (AP-ESI) m/
z Calcd for C18H19N3O6S2 [M+H]+ 438.0788. Found: 438.0782.
(m, J = 7.2 Hz, 2H), 1.51 (m, J = 7.2 Hz, 2H), 1.70 (m, J = 7.2 Hz, 2H),
1.94 (t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 7.78 (d, J = 8.4 Hz,
2H), 7.98 (d, J = 7.8 Hz, 2H), 8.10 (d, J = 8.4 Hz, 1H), 8.21 (dd,
J = 8.4 Hz 1.2 Hz, 1H), 8.62 (d, J = 1.2 Hz, 1H), 8.63 (s, 1H), 10.34
(s, 1H), 11.05 (s, 1H). 13C NMR (DMSO-d6): 24.56, 25.67, 27.68,
32.03, 38.61, 100.42, 110.88, 120.47, 125.29, 126.12, 129.76,
133.09, 137.45, 137.88, 145.45, 158.22, 165.77, 168.93. HRMS
(AP-ESI) m/z Calcd for C20H20IN3O6S [M+H]+ 558.0190. Found:
558.0185.
5.1.7.25.
(E)-6-(1,1-Dioxido-3-oxo-6-(3-(p-tolyl)acrylami-
5.1.7.20.
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-4-methoxybenzamide
(11i).
Yield: 74%, mp: 116–118 °C. 1H NMR (DMSO-d6) d 1.32
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
do)benzo[d]isothiazol-2(3H)-yl)-N-hydroxyhexanamide
(11n). Yield: 45%, mp: 231–233 °C. 1H NMR (DMSO-d6) d 1.27
(m, J = 7.2 Hz, 2H), 1.48 (m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz,
2H), 1.92 (t, J = 7.2 Hz, 2H), 2.35 (s, 3H), 3.66 (t, J = 7.2 Hz, 2H),
6.77 (d, J = 15.9 Hz, 1H), 7.27 (d, J = 8.1 Hz, 2H), 7.56 (d, J = 8.1 Hz,
2H), 7.65 (d, J = 15.6 Hz, 1H), 7.96 (dd, J = 8.7 Hz 1.8 Hz, 1H), 8.07
(d, J = 8.4 Hz, 1H), 8.62 (d, J = 1.5 Hz, 1H), 8.67 (s, 1H), 10.34 (d,
J = 1.2 Hz, 1H), 11.05 (s, 1H). 13C NMR (DMSO-d6): 20.98, 24.57,
25.67, 27.71, 32.03, 38.51, 109.60, 119.82, 119.92, 124.21, 126.21,
127.97, 129.61, 131.45, 138.10, 140.21, 142.14, 145.66, 158.19,
164.69, 168.93. HRMS (AP-ESI) m/z Calcd for C23H25N3O6S [M+H]+
472.1537. Found: 472.1531.
(m, J = 7.2 Hz, 2H), 1.51 (m, J = 7.2 Hz, 2H), 1.70 (m, J = 7.2 Hz, 2H),
1.94 (t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 3.86 (s, 3H), 7.11 (d,
J = 8.4 Hz, 2H), 8.01 (d, J = 9.6 Hz, 2H), 8.09 (d, J = 8.4 Hz, 1H), 8.23
(d, J = 9.0 Hz, 1H), 8.64 (d, J = 1.2 Hz, 1H), 8.67 (s, 1H), 10.34 (s, 1H),
10.86 (s, 1H). 13C NMR (DMSO-d6): 24.56, 25.68, 27.70, 32.03,
38.53, 55.48, 110.62, 113.79, 120.02, 125.05, 125.67, 126.03,
130.01, 137.91, 145.91, 158.29, 162.53, 165.71, 168.93. HRMS
(AP-ESI) m/z Calcd for C21H23N3O7S [M+H]+ 462.1329. Found:
462.1324.
5.1.7.21. 6-(1,1-Dioxido-3-oxo-6-(2-phenylacetamido)benzo[d]
isothiazol-2(3H)-yl)-N-hydroxyhexanamide (11j). Yield: 67%,
mp: 165–168 °C. 1H NMR (DMSO-d6) d 1.26 (m, J = 7.2 Hz, 2H),
1.47 (m, J = 7.2 Hz, 2H), 1.66 (m, J = 7.2 Hz, 2H), 1.91 (t, J = 7.2 Hz,
2H), 3.64 (t, J = 7.2 Hz, 2H), 3.76 (s, 2H), 7.23 (m, 5H), 7.91 (dd,
J = 8.4 Hz 1.8 Hz, 1H), 8.04 (d, J = 8.4 Hz, 1H), 8.49 (d, J = 1.5 Hz,
1H), 8.65 (s, 1H), 10.33 (s, 1H), 11.03 (s, 1H). 13C NMR (DMSO-
d6): 24.55, 25.65, 27.68, 32.00, 38.53, 43.25, 109.58, 120.05,
124.22, 126.30, 126.75, 128.36, 129.21, 134.98, 138.12, 145.47,
158.20, 168.84, 170.55. HRMS (AP-ESI) m/z Calcd for C21H23N3O6S
[M+H]+ 446.1380. Found: 446.1382.
5.1.7.26.
dioxido-3-oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)benzamide
(11o).
Yield: 53%, mp: 202–204 °C. 1H NMR (DMSO-d6) d 1.28
4-Fluoro-N-(2-(6-(hydroxyamino)-6-oxohexyl)-1,1-
(m, J = 7.2 Hz, 2H), 1.48 (m, J = 7.2 Hz, 2H), 1.67 (m, J = 7.2 Hz, 2H),
1.92 (t, J = 7.2 Hz, 2H), 3.67 (t, J = 7.2 Hz, 2H), 7.41 (t, J = 8.4 Hz, 2H),
8.07 (m, 3H), 8.20 (dd, J = 8.7 Hz 1.8 Hz, 1H), 8.63 (d, J = 1.5 Hz, 1H),
8.67 (s, 1H), 10.34 (s, 1H), 11.04 (s, 1H). 13C NMR (DMSO-d6): 24.56,
25.67, 27.69, 32.02, 38.55, 110.80, 115.43 (d, J = 21.8 Hz), 120.39,
125.24, 126.12, 130.22 (d, J = 2.3 Hz), 130.74 (d, J = 9.0 Hz),
137.89, 145.57, 158.23, 162.82 (d, J = 249.0 Hz), 165.32, 168.91.
HRMS (AP-ESI) m/z Calcd for C20H20FN3O6S [M+H]+ 450.1130.
Found: 450.1121.
5.1.7.22.
dioxido-3-oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)benzamide
(11k).
Yield: 68%, mp: 198–201 °C. 1H NMR (DMSO-d6) d 1.31
3-Bromo-N-(2-(6-(hydroxyamino)-6-oxohexyl)-1,1-
5.1.7.27.
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-4-nitrobenzamide
(11p). Yield: 51%, mp: 179–181 °C. 1H NMR (DMSO-d6) d 1.28
(m, J = 7.2 Hz, 2H), 1.49 (m, J = 7.2 Hz, 2H), 1.68 (m, J = 7.2 Hz,
2H), 1.91 (t, J = 7.2 Hz, 2H), 3.67 (t, J = 7.2 Hz, 2H), 8.13 (d,
J = 8.4 Hz, 1H), 8.22 (m, 3H), 8.41 (d, J = 8.7 Hz, 2H), 8.64 (d,
J = 1.5 Hz, 1H), 8.68 (s, 1H), 10.35 (s, 1H), 11.35 (s, 1H). 13C NMR
(DMSO-d6): 24.56, 25.67, 27.68, 32.02, 38.62, 111.09, 120.82,
123.62, 125.49, 126.18, 129.52, 137.86, 139.32, 145.16, 149.50,
158.17, 164.84, 168.92. HRMS (AP-ESI) m/z Calcd for C20H20N4O8S
[M+H]+ 477.1075. Found: 477.1070.
(m, J = 7.2 Hz, 2H), 1.49 (m, J = 7.2 Hz, 2H), 1.68 (m, J = 7.2 Hz, 2H),
1.91 (t, J = 7.2 Hz, 2H), 3.67 (t, J = 7.2 Hz, 2H), 7.53 (t, J = 8.1 Hz, 1H),
7.85 (d, J = 7.8 Hz, 1H), 7.98 (dt, J = 8.4 Hz 1.2 Hz, 1H), 8.11 (d,
J = 8.7 Hz, 1H), 8.19 (t, J = 1.8 Hz, 1H), 8.21 (dd, J = 8.4 Hz 1.8 Hz,
1H), 8.61 (d, J = 1.8 Hz, 1H), 8.65 (s, 1H), 10.33 (s, 1H), 11.09 (s,
1H). 13C NMR (DMSO-d6): 24.56, 25.67, 27.70, 32.03, 38.57,
110.95, 120.57, 121.75, 125.33, 126.14, 127.16, 130.46, 130.80,
135.04, 135.94, 137.86, 145.35, 158.21, 164.91, 168.90. HRMS
(AP-ESI) m/z Calcd for C20H20BrN3O6S [M+H]+ 510.0329. Found:
510.0338/512.0399.
5.2. In vitro HDAC assay
5.1.7.23.
oxo-2,3-dihydrobenzo[d]isothiazol-6-yl)-2-naphthamide
(11l).
Yield: 75%, mp: 124–127 °C. 1H NMR (DMSO-d6) d 1.31
N-(2-(6-(Hydroxyamino)-6-oxohexyl)-1,1-dioxido-3-
We performed assays according to the kit instruction. HDAC
came from HeLa cell nucleus extracts, mainly including HDAC1
and HDAC2, and the substrate was an acetylated histone peptide.
The tested compounds and the control drug SAHA were diluted
(m, J = 7.2 Hz, 2H), 1.49 (m, J = 7.2 Hz, 2H), 1.69 (m, J = 7.2 Hz, 2H),
1.91 (t, J = 7.2 Hz, 2H), 3.68 (t, J = 7.2 Hz, 2H), 7.63 (m, 2H), 8.03 (m,
5H), 8.28 (dd, J = 8.7 Hz 1.8 Hz, 1H), 8.66 (m, 3H), 10.33 (s, 1H),
11.21 (s, 1H). 13C NMR (DMSO-d6): 24.57, 25.68, 27.72, 32.03,
38.55, 110.78, 120.32, 124.31, 125.19, 126.14, 127.05, 127.71,
128.25, 128.66, 129.05, 131.05, 131.91, 134.55, 137.93, 145.74,
158.26, 166.50, 168.92, 170.30. HRMS (AP-ESI) m/z Calcd for
to various concentrations. On the 96-well plate, HDAC (5
were incubated at 37 °C with 10 L of various concentrations of
samples and 25 L of substrate. After reacting for 30 min, the mix-
ture (50 L/well) of Color de Lys Developer and TSA was added.
lL/well)
l
l
l
Then, after 30 min the ultraviolet absorption of the wells was mea-
sured on a microtiter-plate reader at 405 nm. The inhibition rates
were calculated from the ultraviolet absorption readings of
C
24H23N3O6S [M+H]+ 482.1380. Found: 482.1387.

1538
L. Han et al. / Bioorg. Med. Chem. 22 (2014) 1529–1538
inhibited wells related to those of control wells. Finally, the IC50
values were determined using a regression analysis of the concen-
tration and inhibition data.
JQ201319), the Program for New Century Excellent Talents in Uni-
versity (No. NCET-12-0337), and Independent Innovation Founda-
tion of Shandong University, IIFSDU (No. 2012JC003).
5.3. MTT assay
Supplementary data
MDA-MB-231, PC-3, KG1 and K562 cells were respectively cul-
tured in RPMI1640 medium containing 10% FBS at 37 °C in 5% CO2
humidified incubator. Cell proliferation was determined by the
MTT (3-[4,5-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium
bromide) assay. Briefly, cells were plated in a 96-well plate at
5000 cells per well, cultured for 8 h in complete growth medium,
then treated with various concentrations of compounds for 48 h.
0.5% MTT solution was added to each well. After further incubation
for 4 h, formazan formed from MTT was extracted by adding
Supplementary data associated with this article can be found, in
the online version, at http://dx.doi.org/10.1016/j.bmc.2014.01.045.
These data include MOL files and InChiKeys of the most important
compounds described in this article.
References and notes
1. Sato, A. Onco. Targets Ther. 2012, 5, 67.
2. Weichert, W. Cancer Lett. 2009, 280, 168.
3. Gryder, B. E.; Sodji, Q. H.; Oyelere, A. K. Future Med. Chem. 2012, 4, 505.
4. Patil, V.; Sodji, Q. H.; Kornacki, J. R.; Mrksich, M.; Oyelere, A. K. J. Med. Chem.
2013, 56, 3492.
150 lL DMSO and mixing for 10 min. Optical density was read with
an microtiter-plate reader at 570 nm.
5. Jiao, J.; Fang, H.; Wang, X.; Guan, P.; Yuan, Y.; Xu, W. Eur. J. Med. Chem. 2009, 44,
4470.
5.4. Docking study
6. Guan, P.; Sun, F.; Hou, X.; Wang, F.; Yi, F.; Xu, W.; Fang, H. Bioorg. Med. Chem.
2012, 20, 3865.
7. Zhang, Y.; Feng, J.; Jia, Y.; Wang, X.; Zhang, L.; Liu, C.; Fang, H.; Xu, W. J. Med.
Chem. 2011, 54, 2823.
8. Zhang, Y.; Fang, H.; Feng, J.; Jia, Y.; Wang, X.; Xu, W. J. Med. Chem. 2011, 54,
5532.
9. Zhang, Y.; Feng, J.; Liu, C.; Zhang, L.; Jiao, J.; Fang, H.; Su, L.; Zhang, X.; Zhang, J.;
Li, M.; Wang, B.; Xu, W. Bioorg. Med. Chem. 2010, 18, 1761.
10. Sommermeyer, H.; Schreiber, R.; Greuel, J. M.; De Vry, J.; Glaser, T. Eur. J.
Pharmacol. 1993, 240, 29.
11. Blanchet, J.; Macklin, T.; Ang, P.; Metallinos, C.; Snieckus, V. J. Org. Chem. 2007,
72, 3199.
12. Youdim, M. B.; Ashkenazi, R. Eur. J. Pharmacol. 1985, 119, 39.
13. Gomez, Vidal, J. A.; Dominguez, Seglar, J. F.; Tabraue, Chavez, M. PCT Int. Appl.
WO/2008/003800 A1.
14. Hiroyoshi, K.; Shuji, Y.; Masato, N. Bull. Chem. Soc. Jpn. 1982, 55, 3824.
15. Morris, G. M.; Huey, R.; Lindstrom, W.; Sanner, M. F.; Belew, R. K.; Goodsell, D.
S.; Olson, A. J. J. Comput. Chem. 2009, 30, 2785.
16. Pettersen, E. F.; Goddard, T. D.; Huang, C. C.; Couch, G. S.; Greenblatt, D. M.;
Meng, E. C.; Ferrin, T. E. J. Comput. Chem. 2004, 25, 1605.
17. Li, Z.; Mu, X.; Fan, Z.; Li, Y.; Liu, B. CN 200510013913.
AutoDock 4.2 was used for all docking calculations. One hun-
dred runs were performed using Lamarckian Genetic Algorithm
(LGA) with default parameters. The molecular structures were gen-
erated with Sybyl/Sketch module and optimized using semiempir-
ical MOPAC/AM1 method and then assigned with AM1-BCC
charges. Results differing less than 0.5 Å in positional root-mean-
square deviation (RMSD) were clustered together. Conformations
in first cluster with the most favorable free binding energy were
selected as the best docking result.
Acknowledgments
This work was supported by National Natural Science
Foundation China (Nos. 81373281, 21172133), Shandong Provin-
cial Natural Science Foundation (No. ZR2010HM028), Shandong
Natural Science Fund for Distinguished Young Scholars (No.