Discovery and optimization of benzenesulfonanilide derivatives as a novel class of 11β-HSD1 inhibitors

Article abstract of DOI:10.1016/j.bmcl.2012.04.005

A novel series of benzenesulfonanilide derivatives of 11β-HSD1 inhibitors were identified via modification of the sulfonamide core of the arylsulfonylpiperazine lead structures. The synthesis, in vitro biological evaluation, and structure-activity relationship of these compounds are presented. Optimization of this series rapidly resulted in the discovery of compounds (S)-10 and (S)-23 (11β-HSD1 SPA IC₅₀ = 1.8 and 1.4 nM, respectively).

Full text of DOI:10.1016/j.bmcl.2012.04.005

Bioorganic & Medicinal Chemistry Letters 22 (2012) 3786–3790
Contents lists available at SciVerse ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Discovery and optimization of benzenesulfonanilide derivatives as a novel
class of 11b-HSD1 inhibitors
⇑
Yosup Rew , Michael DeGraffenreid, Xiao He, Juan C. Jaen , Dustin L. McMinn, Daqing Sun, Hua Tu,
Stefania Ursu, Jay P. Powers
Amgen Inc., 1120 Veterans Boulevard, South San Francisco, CA 94080, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A novel series of benzenesulfonanilide derivatives of 11b-HSD1 inhibitors were identified via modifica-
tion of the sulfonamide core of the arylsulfonylpiperazine lead structures. The synthesis, in vitro biolog-
ical evaluation, and structure–activity relationship of these compounds are presented. Optimization of
this series rapidly resulted in the discovery of compounds (S)-10 and (S)-23 (11b-HSD1 SPA IC50 = 1.8
and 1.4 nM, respectively).
Received 8 February 2012
Revised 29 March 2012
Accepted 2 April 2012
Available online 9 April 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
11b-Hydroxysteroid dehydrogenase type 1
(11b-HSD1) inhibitor
Benzenesulfonanilide
One of the key regulatory roles of glucocorticoids is glucose
homeostasis. In this regard, glucocorticoids regulate gluconeogen-
esis in the liver and inhibit peripheral glucose uptake in muscle
and adipose tissue. 11b-Hydroxysteroid dehydrogenase type 1
(11b-HSD1), a NADPH-dependent reductase, is a key enzyme that
converts the inactive glucocorticoid cortisone to the active gluco-
corticoid hormone cortisol in liver, adipose, and brain. Excessive
concentrations of glucocorticoids in the liver and adipose tissue
can lead to glucose intolerance and insulin resistance.1 In recent
decades, selective inhibition of the 11b-HSD1 enzyme has been
considered to be a promising strategy for improving insulin sensi-
tivity and treating type II diabetes.2
CF3
O
HO
N
NH2
N
S
O
O
hHSD1 SPA IC50 = 0.7 nM
h293 IC50 = 14 nM
1
Figure 1. Representative arylsulfonylpiperazine 11b-HSD1 inhibitor.3b
O
CF3
CF3
HO
HO
b
a
Previous research within our laboratories described a series of
arylsulfonylpiperazine derivatives,3 exemplified by compound 1,
as potent 11b-HSD1 inhibitors (Fig. 1). Compound 1 was a potent,
selective, and orally bioavailable inhibitor with efficacy in a cyno-
molgus monkey ex vivo enzyme inhibition model.3a
Compound 1 is known to bind to the substrate site in a V-
shaped binding mode, and the central sulfonyl group is located
near the catalytic triad residues of the enzyme.3 We recently suc-
ceeded in the expansion of structural diversity and optimization
of structurally distinguished amide4 and sulfone5 series as novel
11b-HSD1 inhibitors. Replacement of the central sulfonamide
functional group with other isosteric core moieties has been con-
tinuously fascinating to us, and herein we report on another novel
NO2
NO2
NH2
2
4
3
4
CF3
HO
c
O O
S
N
H
d
6
CF3
CF3
HO
HO
c
7
, R=Me
O O
S
8, R=Et
9, R=i-Pr
NH
R
N
R
5
Scheme 1. Reagents and conditions: (a) TMS-CF3, TBAF, THF, 93%; (b) SnCl2, EtOH,
94%; (c) benzenesulfonyl chloride, pyridine, DCM, 58ꢀ92%; (d) for R = Me and Et: (i)
Boc2O, NaHCO3, THF/H2O, 100%; (ii) NaH, MeI (85%) or EtBr (70%), DMF; (iii) TFA,
100%; for R = i-Pr: acetone, AcOH, NaBH3CN, AcCN, 80%.
⇑
Corresponding author. Tel.: +1 650 244 2682.
E-mail address: yrew@amgen.com (Y. Rew).
Currently at ChemoCentryx, Inc., Mountain View, CA 94043, USA.
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.04.005

Y. Rew et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3786–3790
3787
Table 1
Table 2
Inhibition of 11b-HSD1 by selected analogs: initial N-alkylation
Sulfonamide aryl modification
CF3
HO
CF3
HO
O O
O O
S
S
N
N
X
R
Compounda
R
hHSD1 SPAb IC50 (nM)
hHSD1
h293c (cell) h293 (cell, 3%
IC50 (nM)
Compounda
SPAb IC50
(nM)
6
7
8
9
H
Me
Et
>1000
>1000
300
HSAd) IC50 (nM)
X
i-Pr
21.4
9
21.4
3.4
N/D
N/D
49
a
All compounds were racemates and gave satisfactory 1H NMR, HPLC, and MS
data that were in full agreement with their proposed structures; purity (>95%) was
determined by HPLC analysis.
Cl
b
Potency data were reported as the average of at least two determinations and
10
9.0
IC50 values determined by a scintillation proximity assay.
Cl
Cl
11
12
15
22
262
N/D
CF3
CF3
HO
SO2Cl
X
HO
O O
S
a
27.8
N/D
X
+
N
NH
Br
13
14
15
16
17
14
7.4
33
39
5.3
6.6
9.9
29
86
5
10 17 19 25, 29, 30
-
,
-
F
CF3
CF3
HO
HO
HO
48
Br
O O
S
O O
S
b
c
N
N
CN
CF3
NO2
261
769
103
18
13
CF3
CF3
HO
Cl
Cl
O O
O O
71
S
S
N
N
25
26
8.0
NO2
NH2
d
e
CF3
CF3
HO
HO
18
41
144
>1000
Cl
Cl
Br
Cl
O O
O O
S
S
N
N
SO2Me
19
20
21
652
3.1
9.7
548
11.2
14
>1000
91
27
28
NHAc
b
CF3
HO
O O
S
Cl
Cl
N
108
Cl
31
22
23
19.1
3.1
N/D
9.0
N/D
Scheme 2. Reagents and conditions: (a) pyridine, DCM, 16ꢀ76%; (b) cyclo-
propylboronic acid, K3PO4, Pd(PPh3)4, toluene/H2O = 10/1, 81ꢀ96%; (c) SnCl2, EtOH,
quantitatively; (d) Ac2O, DMF, 73%; (e) isoamylnitrite, CuBr2, AcCN, 91%.
Cl
Cl
class of 11b-HSD inhibitors (6ꢀ31 and 36ꢀ44), which have a retro-
inverso sulfonamide isosteric core.
54
As an initial SAR effort, a series of simple benzenesulfonanilides,
compounds 6ꢀ9, were synthesized as described in Scheme 1.
Cl
(continued on next page)

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Y. Rew et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3786–3790
CF3
Table 2 (continued)
CF3
O
TMSO
HO
b
a
hHSD1
SPAb IC50
(nM)
h293c (cell) h293 (cell, 3%
IC50 (nM)
Compounda
HSAd) IC50 (nM)
X
Br
NH
R
Br
32
4
33
34
Cl
24
13
10
N/D
N/D
c
Cl
c
36
, R=cyclopropyl
, R=cyclobutyl
, R=Ph
38
44
Cl
CF3
CF3
HO
HO
25
26
27
15
113
Cl
O O
S
Cl
O O
S
d
N
NO2
Cl
N
R
H
35
37, R=t-Bu
39, R=cyclopentyl
F
40, R=cyclopropylmethyl
O O
S
15
63
271
41
, R=2-methylpropyl
F
42
, R=
O
F
NH2
Cl
a
F
O O
S
43
, R=2,2,2-trifluoroethyl
CF3
256
498
>1000
Cl3C
O
b
NHAc
Cl
Scheme 3. Reagents and conditions: (a) TMSCF3 (1.5 equiv), TBAF (0.0075 equiv),
THF, 77%; (b) for R = cyclopropyl and cyclobutyl: RNH2, Pd2(dba)3, BINAP, t-BuONa,
toluene; 1 M TBAF, 49ꢀ80%; for R = Ph: RNH2, Pd2(dba)3, BINAP, Cs2CO3; 1 M TBAF,
43%; (c) 2-chlorobenzenesulfonyl chloride, pyridine, 12ꢀ92% (d) for 37 and 39–41:
RBr, K2CO3, DMF, 13ꢀ93%; for 42: (a) K2CO3, DMF, 73%; for 43: (b) K2CO3, DMF, 10%.
28
29
30
3.3
4.5
21
19
19
47
106
103
268
Br
Cl
biochemical assay. However, as the size of the N-alkyl substituent
increased, in vitro biochemical potency improved. Although the
methyl analog (7) was inactive, the ethyl analog 8 displayed a
moderate activity (IC50 = 300 nM).
A 15-fold increase in the
Cl
potency was observed when the ethyl group of compound 8 was
replaced by the isopropyl group (compound 9: IC50 = 21 nM).
This interesting result led us to focus on further SAR with this
benzenesulfonanilide series. To explore SAR of the aryl sulfonyl
group systematically, we synthesized a variety of analogs with a
modified aryl sulfonyl group (10ꢀ31 in Scheme 2).
CF3
Cl
Most compounds (10ꢀ17, 19ꢀ25, 29, and 30) were prepared by
direct sulfonylation of 5 with a substituted benzenesulfonyl chlo-
ride. The Suzuki coupling reaction of 13 and 28 with cyclo-
propylboronic acid gave 18 and 31, respectively. The nitro
compound 25 was reduced to amine 26 under SnCl2 conditions,
and further acetylation gave 27. Treatment of the diazonium salt,
which was derived from 26, with CuBr2 provided 28. Compounds
were evaluated for the inhibition of human 11b-HSD1 enzymes
in both biochemical assays and cell-based assays (Table 2).6
Screening a small focused library with a Cl substituent revealed
that substitution at the 2-position improved11b-HSD1 inhibition
(9ꢀ12 in Table 2). Compound 10, a 2-Cl analog, is significantly
more potent than its unsubstituent phenyl analog (9). Shifting
the substituent to the meta- and para-positions also led to a drop
in activity (11 and 12).
Further derivatization at the 2-position was investigated
(13ꢀ20). The 2-Cl analog (10) was still the most potent compound,
and the 2-F and 2-Me analogs (14 and 20) showed potencies
comparable to that of 10. Additional substitutions at the 3, 4, 5,
or 6 positions were then evaluated while preserving the 2-Cl sub-
stituent (21ꢀ24). Compound 23, the 2,5-dichlorophenyl analog,
showed potency similar to that of 10; whereas the potency of all
the other analogs was diminished. Lastly, we tried to replace the
C-5 Cl group with other substituents (25ꢀ31) but none of those
analogs was superior to 23 in terms of potency.
31
45
133
612
All compounds were racemates and gave satisfactory 1H NMR, HPLC, and MS
data that were in full agreement with their proposed structures; purity (>95%) was
determined by HPLC analysis.
IC50 values determined by a scintillation proximity assay (all potency data are
reported as the average of at least two determinations).
h293 = HEK 293 cells were stably transfected with full-length human 11b-HSD1
(all potency data are reported as the average of at least two determinations).
HAS = human serum albumin (all potency data are reported as the average of at
least two determinations).
a
b
c
d
Synthesis began with the conversion of 40-nitroacetophenone 2
into the key intermediate aniline 4. Treatment of 2 with TMS-
CF3, followed by reduction of the nitro group in 3 with SnCl2
provided aniline 4. Direct sulfonylation of 4 with benzenesulfonyl
chloride afforded compound 6. Preparation of N-monoalkyl ani-
lines 5 by N-alkylation of a Boc-protected aniline (R = Me and Et)
or direct reductive amination (R = i-Pr), followed by sulfonylation
gave compounds 7ꢀ9.
Compounds were evaluated for the inhibition of human 11b-
HSD1 (Table 1).6 The initial primary phenyl-sulfonamide, com-
pound 6, exhibited no activity as an enzyme inhibitor in the

Y. Rew et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3786–3790
3789
Table 3
N-alkyl modification
CF3
HO
Cl
O O
S
N
R
Compounda
R
hHSD1 SPAb
IC50 (nM)
h293c (cell)
IC50 (nM)
h293 (cell, 3%
HSAd) IC50 (nM)
10
36
37
38
3.4
40
13
20
9.0
19
42
46
49
411
614
441
39
40
61
46
144
112
>1000
>1000
41
42
89
19
185
29
>1000
162
Figure 2. Single X-ray crystal structure of (S)-10.
F
Table 4
F
Effect of stereochemistry at the trifluoromethyl carbinol moiety
CF3
HO
43
44
116
134
313
620
>1000
N/D
CF3
Cl
X
O O
S
S
10
)- , X = H
(
N
23
(S)- , X = Cl
a
All compounds were racemates and gave satisfactory 1H NMR, HPLC, and MS
data that were in full agreement with their proposed structures, and purity (>95%)
was determined by HPLC analysis.
Compounda
X
hHSD1 SPAb
IC50 (nM)
h293c (cell)
IC50 (nM)
h293 (cell, 3% HSAd)
IC50 (nM)
b
IC50 values determined by a scintillation proximity assay (all potency data are
reported as the average of at least two determinations).
c
h293 = HEK 293 cells stably transfected with full length human 11b-HSD1 (all
10
H
H
H
3.4
1.8
113
9.0
5.8
138
9.0
2.2
200
49
25
>1000
54
21
potency data are reported as the average of at least two determinations).
(S)-10
(R)-10
23
(S)-23
(R)-23
d
HSA = human serum albumin (all potency data are reported as the average of at
least two determinations).
Cl 3.1
Cl 1.4
Cl 106
>1000
a
All compounds gave satisfactory 1H NMR, HPLC, and MS data that were in full
With the discovery of the improved potency imparted by the
2-Cl phenyl group to sulfonyl functionality, we returned to investi-
gate further modifications of the N-alkyl substituents in 10.
Compounds 36ꢀ44 were prepared as outlined in Scheme 3. Treat-
ment of ketone 32 with TMS-CF3, followed by the Buchwald-
Hartwig coupling reaction with the primary amines of 33 and
deprotection of the trifluoromethyl carbinol group provided 34.
Sulfonylation of 34 with 2-chlorobenzenesulfonyl chloride affor-
ded compound 36, 38, and 44. The other N-alkyl derivatives (37
and 39ꢀ43) were prepared by direct alkylation of the primary sul-
fonamide 35. Unfortunately, in this broad set of analogs, replace-
ment of the isopropyl group resulted in a reduction in potency
(Table 3).
Chiral separation of the most potent analogs, 10 and 23, was
achieved by preparative normal phase chiral HPLC (Chiralpak AD)
and, as observed in our previously reported trifluoromethyl carbi-
nol containing analogs, the (S) configuration proved to have greater
11b-HSD1 inhibitory activity.3–5 In this benzenesulfonanilide ser-
ies, the absolute configuration of the trifluoromethyl carbinol
agreement with their proposed structures, and purity (>95%) was determined by
HPLC analysis.
b
IC50 values determined by a scintillation proximity assay (all potency data are
reported as the average of at least two determinations).
c
h293 = HEK 293 cells stably transfected with full length human 11b-HSD1 (all
potency data are reported as the average of at least two determinations).
d
HSA = human serum albumin (all potency data are reported as the average of at
least two determinations).
was determined by single X-ray crystallography of the active iso-
mer of compound 10 (Fig. 2) and the (S)-enantiomers are about
over 60 times more potent than the corresponding (R)-isomers in
both biochemical and cellular assays (Table 4).
In summary, we have identified a novel class of benzenesulfo-
nanilide inhibitors of the human 11b-HSD1. Optimization of this
series rapidly resulted in the discovery of compounds (S)-10 and
(S)-23, with single-digit nanomolar potency in both biochemical
and cell-based assays.

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Y. Rew et al. / Bioorg. Med. Chem. Lett. 22 (2012) 3786–3790
Zhang, J.; Bartberger, M. D.; Li, V.; Syed, R.; Jordan, S.; Komorowski, R.; Chen, M.
Acknowledgements
M.; Cupples, R.; Kim, K. W.; St. Jean, D. J., Jr; Johansson, L.; Henriksson, M. A.;
Williams, M.; Vallgarda, J.; Fotsch, C.; Wang, M. J. Med. Chem. 2010, 53, 4481.
3. (a) Sun, D.; Wang, Z.; Cardozo, M.; Choi, R.; DeGraffenreid, M.; Di, Y.; He, X.; Jaen,
J. C.; Labelle, M.; Liu, J.; Ma, J.; Miao, S.; Sudom, A.; Tang, L.; Tu, H.; Ursu, S.;
Walker, N.; Yan, X.; Ye, Q.; Powers, J. P. Bioorg. Med. Chem. Lett. 2009, 19, 1522;
(b) Sun, D.; Wang, Z.; Di, Y.; Jaen, J. C.; Labelle, M.; Ma, J.; Miao, S.; Sudom, A.;
Tang, L.; Tomooka, C. S.; Tu, H.; Ursu, S.; Walker, N.; Yan, X.; Ye, Q.; Powers, J. P.
Bioorg. Med. Chem. Lett. 2008, 18, 3513.
The authors would like to thank Dr. Frederick Hollander at the
University of California, Berkeley for solving the single X-ray crys-
tal structure of compound (S)-10.
References and notes
4. (a) Sun, D.; Wang, Z.; Caille, S.; DeGraffenreid, M.; Gonzalez, F.; Hungate, R.;
Jaen, J. C.; Jiang, B.; Julian, L. D.; Kelly, R.; McMinn, D. L.; Kaizerman, J.; Rew, Y.;
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6. 11b-HSD1 enzyme activity was determined by measuring the conversion of
[3H]-cortisone to [3H]-cortisol. Product [3H]-cortisol, captured by an anti-
cortisol monoclonal antibody conjugated to scintillation proximity assay (SPA)
beads, was quantified with
a microscintillation plate reader. Biochemical
enzyme assays were performed with Baculovirus-produced recombinant full-
length human or mouse 11b-HSD1 as the enzyme source and NADPH as
cofactor. Cell-based enzyme assays (h293) utilized HEK293 cells stably
expressing recombinant human full-length 11b-HSD1 as the enzyme source
without supplementation of NADPH. IC50 values for enzyme inhibition were
calculated with a dose response curve fitting algorithm with at least duplicate
sets of samples. In the cellular assay, selected compounds were tested in the
presence of human serum albumin (HSA) to measure the impact of protein
binding.