Synthesis and biological evaluation of novel, selective, nonsteroidal glucocorticoid receptor antagonists

Article abstract of DOI:10.1016/j.bmcl.2004.02.048

We report the discovery of a novel class of glucocorticoid receptor (GR) antagonists based on the chromene molecular scaffold. The compounds exhibit good functional potency and an improved receptor selectivity profile for GR over other steroid receptors when compared to the classical steroidal GR-antagonist, RU-486.

Full text of DOI:10.1016/j.bmcl.2004.02.048

Bioorganic & Medicinal Chemistry Letters 14 (2004) 2079–2082
Synthesis and biological evaluation of novel, selective, nonsteroidal
glucocorticoid receptor antagonists
Irini Akritopoulou-Zanze,a,* Jyoti R. Patel,a Kresna Hartandi,a
Jehrod Brenneman,a Martin Winn,a John K. Pratt,a Marlene Grynfarb,b
Annika Goos-Nisson,b Thomas W. von Gelderna and Philip R. Kyma
aAbbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60044, USA
bKaro Bio, Novum, SE-141 57Huddinge, Sweden
Received 3 December 2003; revised 11 February 2004; accepted 12 February 2004
Abstract—We report the discovery of a novel class of glucocorticoid receptor (GR) antagonists based on the chromene molecular
scaffold. The compounds exhibit good functional potency and an improved receptor selectivity profile for GR over other steroid
receptors when compared to the classical steroidal GR-antagonist, RU-486.
Ó 2004 Elsevier Ltd. All rights reserved.
The glucocorticoid receptor (GR) is a member of the
soluble intracellular steroid receptor superfamily that
function as ligand-mediated transcription factors to
control gene expression.1 Glucocorticoids bind to the
GR, and the resulting GR/ligand complex can either
initiate gene transcription by binding to glucocorticoid
receptor response sequences (GREs) on DNA or inhibit
transcription by repressing the activity of other tran-
scription factors such as NFjB or AP-1.2 The initiation
or repression of transcription events is determined by
the topology of the GR/ligand complex, which is ulti-
mately related to the structure of the GR-modulator.3
activity as a progesterone receptor antagonist limits its
pharmaceutical use as a GR-antagonist.
Nonsteroidal pharmacophores may offer
a better
opportunity for achieving the desired steroid receptor
selectivity profile, however, there are only limited
examples of nonsteroidal GR-antagonists reported in
the literature.8 Previous efforts at Abbott have focused
on the optimization of chromene-based, receptor selec-
tive GR-modulators 3 that demonstrate an altered
gene regulation profile compared to steroids.9 In this
work, we describe our efforts to optimize a novel,
Glucocorticoid receptor antagonists such as RU-486 1
have been shown to be effective at blocking gene-tran-
scription mediated by endogenous glucocorticoids such
as cortisone 2. The utility of GR-antagonists in treating
conditions that result from high levels of circulating
glucocorticoids has been demonstrated by the use of
RU-486 for the treatment of the Cushingꢀs syndrome,4
diabetes,5 glaucoma,6 and depression.7 While RU-486
has demonstrated the potential therapeutic utility of
GR-antagonists, it is limited by cross-reactivity with
other steroid hormone receptors. Most notably, its
Keywords: Glucocorticoid receptor (GR) antagonists; Chromenes;
Nonsteroidal.
* Corresponding author. Tel.: +1-847-9375006; fax: +1-847-9350310;
e-mail: irini.zanze@abbott.com
0960-894X/$ - see front matter Ó 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2004.02.048

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receptor-selective GR-antagonist based on the chro-
mene scaffold. Screening of our compound repository
identified chromene 4 as a novel, nonsteroidal GR-
antagonist.
Herein, we describe our efforts to improve activity and
increase selectivity of this lead compound. We have
devised short and versatile synthetic routes that allow us
to access a variety of substitution patterns on the
chromene core (Schemes 1–3). Resorcinol 5 (Scheme 1)
was dialkylated with MOMCl and the resulting ether
was treated with n-BuLi followed by ZnCl2 to generate
the organozinc reagent 6 in situ. This compound was
immediately reacted with methyl-2-bromo-5-nitro-
benzoate under palladium-catalyzed conditions to form
the biaryl intermediate 7 in good overall yield. The nitro
arene was then reduced and the resulting amine was
treated with MsCl. DIBAL reduction of methyl ester 8
Scheme 2. (a) H2, 10% Pd/C, 4 atm, 1 h, quant.; (b) PhLi, Et2O/
cyclohexane, )5 °C, 1 h, 85%; (c) NaBH4, EtOH, 65 °C, 1 h, 80%; (d)
4 N HCl in dioxane, MeOH, rt, 16 h, 87%; (e) RSO2Cl, pyridine,
CHCl3, 80%; (f) RCOCl, PS–DIEA, CH2Cl2; (g) RCHO, DIEA, PS–
BH3, MeOH.
Scheme 3. (a) p-TsOH, MeOH, rt, 3 h, 99%; (b) BF3ÆEt2O, CH2Cl2,
)10 °C, RZnX, 9–58%.
to the corresponding alcohol and subsequent oxidation
of the alcohol under TPAP/NMO conditions provided
aldehyde 9 in high yields. Addition of PhLi at low
temperature provided the corresponding benzhydrol,
which was treated with acid to effect ring closure and
simultaneous deprotection of the C1 hydroxyl.
Compound 10 can be used as a starting material for a
variety of transformations such as alkylations to provide
ethers 11 or via the triflate for Stille couplings to afford
compounds 13. Likewise, as shown in Scheme 2, biaryl
intermediate 14 can be prepared in a similar fashion to 7
by starting with the Weinreb amide of 2-bromo-5-
nitrobenzoic acid. Reduction of the nitro group and
reaction with PhLi provided ketone 15, which upon
reduction to the alcohol and treatment with acid, yielded
intermediate 16. Aniline 16 was subjected to a variety of
acylations, sulfonylations, and reductive aminations to
furnish derivatives of general structure 17. Following a
similar route to the one delineated in Scheme 1, alde-
hyde 19 (Scheme 3) was prepared from 3-(methoxy-
methoxy)anisole.10 Ring closure of 19 with p-TsOH and
reaction of the resulting acetal with organozinc reagents
under BF3ÆEt2O catalysis afforded compounds substi-
tuted at C6.
Scheme 1. (a) NaH, DMF, MOMCl, 0 °C to rt, overnight, 99%; (b) n-
BuLi, hexanes, THF, )30 °C, rt, 1 h, then ZnCl2, 0 °C, rt, 2 h; (c)
methyl-2-bromo-5-nitrobenzoate, Pd(PPh3)2Cl2, 65 °C, overnight, 68%
in two steps; (d) Fe, NH4Cl, aq EtOH, 95 °C, 6 h, 52%; (e) MeSO2Cl,
pyridine, 0 °C to rt, overnight, 97%; (f) DIBAL, heptane, CH2Cl2, )78
ꢀ
to 0 °C, 2 h, 82%; (g) TPAP, NMO, powdered 4 A MS, MeCN, rt, 2 h,
All compounds were tested for their binding affinity to
the human glucocorticoid receptor and to the related
progesterone, mineralocorticoid, androgen, and estro-
gen receptors in order to monitor selectivity. They were
85%; (h) PhLi, THF, )78 °C, 2 h, then MeOH, 97%; (i) 2 M HCl in
Et2O, MeOH, rt, 20 h, 93%; (j) Tf2O, Et3N, CH2Cl2, )78 °C, 10 min,
0 °C, 20 min, 72%; (k) Bu3SnR, Pd(PPh3)4, DMF, 120 °C, 14 h, 54–
97%; (l) BSA, THF, 0 °C, 1 h, then KOtBu, RX, 2 h, 29–78%.

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Table 1. C1-SAR. Human GR-binding affinitya and whole cell GRAF
functional assayb
Table 2. C8-SAR. Human GR-binding affinitya and whole cell GRAF
functional assayb
Compounds R1
GR
IC50 (nM)
GRAF
IC50 (nM)
Compounds R2
GR
IC50 (nM)
GRAF
IC50 (nM)
10
–OH
–OMe
–OEt
892 (559–1423)
19 (17–21)
81 (70–92)
2 (2–2)
1805
87
20
16
–H
–NH2
10,000 1914
1937 (1273–2947) 2017
11a
11b
11c
13a
13b
13c
308
57
11a
17a
17b
17c
17d
–NHSO2Me
–N(Me)SO2Me
–NHSO2Et
–NHSO2N(Me)2
–NHSO2–
(2-thiophenyl)
–NHSO2Ph
–NHCOCH3
–NHCOEt
–NHCOPh
–NHEt
19 (17–21)
1053 (949–1169)
62 (61–63)
87
210
251
121
93
–OCF2H
–CH2OH
–CO2Me
–2-Thiophenyl
180 (150–220)
ND
1204 (1382–1049) ND
656 (639–673) ND
41 (26–67)
18 (13–26)
a Binding affinities as measured by IC50s (the concentration of com-
pound required to inhibit 50% of the binding of [3H]-dexamethasone).
Values of IC50s with ranges (in parentheses) are reported as geometric
means of two experiments done in duplicate and values without
ranges are from a single experiment done in duplicate.
17e
17f
17g
17h
17i
17j
146 (133–161)
117 (106–131)
160 (159–161)
404 (294–554)
564 (379–840)
910 (838–988)
137
69
124
289
382
402
b A genetically engineered, mammalian cell line expressing GR. IC50
s
–NHCH2Ph
are determined from 12-concentration compound curves. (ND ¼ not
a;b See Table 1.
determined).
also tested in a whole cell assay to measure functional
cellular GR-antagonism (GRAF).11
Table 3. C6-SAR. Human GR-binding affinitya and whole cell GRAF
functional assayb
It was determined at an early stage that the bromine
group at position 7 was not necessary for activity. In
fact, removal of the bromine resulted in compound 11a
(Table 1), which was more potent and selective than the
initial lead 4. Subsequently all other analogs were syn-
thesized with hydrogen at position 7.
Compounds
R3
GR
IC50 (nM)
GRAF
IC50 (nM)
Substitutions at C1 had a remarkable effect on activity.
Replacement of the methoxy group with the difluoro-
methyl unit resulted in a more potent compound 11c.
Phenol 10, larger substituents (e.g., 11b and 13c) or polar
groups (13a and 13be) had a detrimental effect on activity.
11a
19a
19b
19c
19d
19e
19f
19g
19h
19i
Phe
19 (17–21)
812 (681–974)c
6 (5–6)
87
665
122
21
2-MeOPhe
3-MeOPhe
3-MePhe
1
4-MePhe
7 (6–7)c
ND
78
We then turned our attention to position 8 (Table 2), to
examine the importance of the methanesulfonamide
substituent. Removal of this unit altogether (compound
20) led to loss of potency. Similarly, the free amine 16
and the N-methyl substituted sulfonamide 17a were
considerably less active than the initial sulfonamide 11a.
A parallel synthesis approach was undertaken to opti-
mize the SAR at the amino terminus. A variety of sul-
fonamides, amides, and amines we synthesized from the
free amino core 16. We observed no significant
improvement in activity from this exercise although,
many compounds exhibited similar activities to the
parent 11a. Sulfonamides were in general better than
amides and amines.
3,5-MePhe
3-FPhe
4-FPhe
2
3 (3–4)c
76
29 (23–33)c
3 (3–3)
ND
147
129
378
ND
66
3-ClPhe
4-ClPhe
10 (9–12)
3 (3–4)
19j
3,4-ClPhe
4-EtOBn
19k
19l
548 (536–560)
7 (6–8)
2-Thiophenyl
3-Thiophenyl
3-PhOPhe
4-PhOPhe
3-EtO(CO)Phe
4-EtO(CO)Phe
3-HOPhe
2-Pyridyl
3-Pyridyl
3-MeNHPhe
Cyclohexyl
n-Pentyl
19m
19n
19o
19p
19q
19r
19s
19t
19u
19v
19w
11 (10–12)
48 (44–53)
63
43
434
847
296
388
ND
ND
ND
180
630
ND
31 (28–34)
61 (39–94)
216 (215–217)
1430 (1428–1433)
460 (366–578)
23
Thus far all the compounds had a phenyl group at C6.
To explore a more diverse array of C6-substituents, we
developed a robust and versatile synthesis that utilized
Lewis-acid catalyzed addition of aryl, heteroaryl, and
alkyl zinc reagents to a chromene–lactol intermediate
47 (43–50)
21
a;b See Table 1.
c Values are the geometric mean of three experiments done in duplicate.

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Table 4. Human GR,a PR, MR, AR, and ERa;d binding affinities and whole cell GRAF functional assayb
Compounds
R1
R3
GR
IC50 (nM)
PR-1
IC50 (nM)
MR-1
IC50 (nM)
AR-1
IC50 (nM)
ERa-1
IC50 (nM)
GRAF
IC50 (nM)
RU-486
4
1
3
10,000
3355
6896
367
6000
454
89
ND
ND
2281
5
430
87
519 (378–814)c
19 (17–21)
81 (70–92)
2 (2–2)
1
11a
11b
11c
19c
19d
19e
19f
–OMe
–OEt
–Phe
–Phe
22,897
893
162
6525
>10,000
8727
>10,000
>10,000
>10,000
ND
308
57
–OCF2H
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–OMe
–Phe
3-MePhe
4-MePhe
3,5-MePhe
3-FPhe
4-FPhe
3-ClPhe
2-Thiophenyl
236
673
333
651
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
>10,000
21
7 (6–7)c
>10,000
ND
ND
78
2
210
476
1220
683
3 (3–4)c
29 (23–33)c
3 (3–3)
7 (6–8)
>10,000
>1000
76
19g
19h
19l
1157
498
2484
2154
2252
ND
147
66
>10,000
>10,000
450
a;b See Table 1.
c See Table 3.
d The following radiolabeled standards were used: [3H]-progesterone (PR), [3H]-aldosterone (MR), [3H]-mibolerone (AR), [3H]-estrodiol (ER).
derived from aldehyde 18 as shown in Scheme 3. Fol-
lowing this route, we prepared numerous analogs and
were able to improve the potency by 10-fold to the single
digit nanomolar range as exemplified by analogs 19c and
19h (Table 3). Substitution patterns on the phenyl ring
clearly defined an SAR in this series. meta-Substituted
phenyl analogs were more active than para, but both
sites could accommodate polar groups (19p,q,u) and
large substituents (19n and 19o). Replacement of the
phenyl ring, with a benzyl (19k) or pyridine rings, (19s
and 19t) led to a decrease in potency. However, thio-
phene (19l and 19m) and cyclic (19v) or acyclic (19w)
aliphatic groups were well tolerated.
and >200-fold selectivity versus the other steroid
receptors.
References and notes
1. Evans, R. M. Science 1988, 240, 889–895.
2. (a) Diamond, M. I.; Miner, J. N.; Yoshinaga, S. K.;
Yamamoto, K. R. Science 1990, 249, 1266–1272; (b)
Jonat, C.; Rahmsdorf, H. J.; Park, K. K.; Cato, A. C.;
Gebel, S.; Ponta, H.; Herrlich, P. Cell 1990, 62, 1189–
1204; (c) van der Saag, P. T.; Gustafsson, J.-A. Trends
Endocrinol. Metab. 1997, 65, 1–46.
3. Coghlan, M. J.; Elmore, S. W.; Kym, P. R.; Kort, M. E.
Current Topics Med. Chem. 2003, 3, 1617–1635.
4. Chu, J. W.; Matthias, D. F.; Belanoff, J.; Schatzberg, A.;
Hoffman, A. R.; Feldman, D. J. Clin. Endocrinol. Metab.
2001, 86, 3568–3573.
Compounds that demonstrated potent GR-binding and
functional antagonism were examined in a selectivity
panel of steroid receptors (Table 4).
5. Gettys, T. W.; Watson, P. M.; Taylor, I. L.; Collins, S. Int.
J. Obes. 1997, 21, 865–873.
6. Phillips, C. I.; Green, K.; Gore, S. M.; Cullen, P. M.;
Campbell, M. Lancet 1984, 1, 767–768.
In our previous work with chromene-based GR-modul-
ators we had discovered that the C1-substituent plays an
important role in imparting GR-potency and selectiv-
ity.12 Consistent with these findings, in the chromene
series, the methoxy substituent at C1 (11a) was optimal
for maximum selectivity. Small changes in the C1 sub-
stituent, for example, methoxy (11a) versus ethoxy (11b)
led to a decrease in GR-potency and an erosion of the
index of GR-selectivity. Even the more subtle change of
C1-methoxy (11a) to C1-difluoromethoxy (11c) signifi-
cantly altered the activity and selectivity profiles. Com-
pound 11c was more potent, however a disproportional
increase in binding affinity for the MR receptor was also
observed. Substitution patterns on the C-6 phenyl ring
also played an important role in defining activity and
selectivity. meta-Substituted compounds were in general
more potent and selective than para (e.g., 19c vs 19d and
19f vs 19g) and larger substituents were more selective
than smaller ones (e.g., 19h vs 19f). Refinements in the
C6 substituent led to compound (19c) that demonstrated
>200-fold selectivity for GR versus other steroid recep-
tors and functional antagonism within 4-fold of RU-486.
7. Belanoff, J. K.; Flores, B. H.; Kalezhan, M.; Sund, B.;
Schatzberg, A. F. J. Clin. Psychopharmacol. 2001, 21, 516–521.
8. Morgan, B. P.; Swick, A. G.; Hargrove, D. M.; LaFl-
amme, J. A.; Moynihan, M. S.; Carroll, R. S.; Martin, K.
A.; Lee, E.; Decosta, D.; Bordner, J. J. Med. Chem. 2002,
45, 2417–2424.
9. Coghlan, M. J.; Jacobson, P. B.; Lane, B.; Nakane, M.;
Lin, C. W.; Elmore, S. W.; Kym, P. R.; Luly, J. R.; Carter,
G. W.; Turner, R.; Tyree, C. M.; Hu, J.; Elgort, M.;
Rosen, J.; Miner, J. N. Mol. Endocrin. 2003, 17, 860–869.
10. Kaufman, T. S.; Srivastava, R. P.; Sindelar, R. D. J. Med.
Chem. 1995, 38, 1437–1445.
11. The glucocorticoid hormone responding cell line contains
a stably integrated artificial transcription unit comprised
of a glucocorticoid hormone response element (GRE) and
core promoter sequences fused to a downstream reporter
gene encoding a secreted form of alkaline phosphatase
(ALP). IC50 is reported as the concentration required to
inhibit 50% of the dexamethazone induced ALP-response.
12. Kym, P. R.; Kort, M. E.; Coghlan, J. L.; Moore, J. L.;
Tang, R.; Ratajczyk, J. D.; Larson, D. P.; Elmore, S. W.;
Pratt, J. K.; Stashko, M. A.; Falls, H. D.; Lin, C. W.;
Nakane, M.; Miller, L.; Tyree, C. M.; Miner, J. N.;
Jacobson, P. B.; Wilcox, D. M.; Nguyen, P.; Lane, B. C.
J. Med. Chem. 2003, 46, 1016–1030.
In conclusion, we have discovered a novel class of
chromene-based GR-antagonists. Optimized analogs in
this series demonstrate potencies comparable to RU-486