Synthesis and identification of novel 11β-aryl-4′,5′-dihydrospiro[estra-4,9-diene-17β, 4′-oxazole] analogs with dissociated antiprogesterone activities

Article abstract of DOI:10.1016/j.bmcl.2007.08.064

A series of novel 11β-aryl-4′,5′-dihydrospiro[estra-4,9-diene-17β, 4′-oxazole] analogs have been evaluated for their antagonist hormonal properties using the T47D cell-based alkaline phosphatase assay and the A549 cell-based functional assay. Some of the

Full text of DOI:10.1016/j.bmcl.2007.08.064

Bioorganic & Medicinal Chemistry Letters 17 (2007) 5754–5757
Synthesis and identification of novel 11b-aryl-40,
50-dihydrospiro[estra-4,9-diene-17b,40-oxazole] analogs
with dissociated antiprogesterone activities
a
a,
a,ꢀ
Chunyang Jin,a,* G. Manikumar, John A. Kepler, C. Edgar Cook,
George F. Allan,b Margaret Kiddoe,b Sheela Bhattacharjee,b
Olivia Linton,b Scott G. Lundeenb and Zhihua Suib
*
aCenter for Organic and Medicinal Chemistry, RTI International, PO Box 12194, Research Triangle Park, NC 27709, USA
bJohnson & Johnson Pharmaceutical Research & Development L.L.C., Drug Discovery, 1000 Route 202, Raritan, NJ 08869, USA
Received 8 August 2007; revised 23 August 2007; accepted 27 August 2007
Available online 29 August 2007
Abstract—A series of novel 11b-aryl-40,50-dihydrospiro[estra-4,9-diene-17b,40-oxazole] analogs have been evaluated for their antag-
onist hormonal properties using the T47D cell-based alkaline phosphatase assay and the A549 cell-based functional assay. Some of
the compounds showed highly potent, and more selective antiprogestational activity against antiglucocorticoid activity than mife-
pristone (RU 486).
Ó 2007 Elsevier Ltd. All rights reserved.
Progesterone, mediated by interaction with progester-
one receptor (PR), plays a critical role in the regulation
of female reproductive events associated with the estab-
lishment and maintenance of pregnancy.1 It also has less
clearly defined functions in the brain, the immune sys-
tem, and the vascular endothelial system. The last two
decades have witnessed the development of synthetic
compounds that range from full PR antagonists to com-
pounds with mixed agonist/antagonist actions, the latter
also known as selective progesterone receptor modula-
tors (SPRMs).2 Many such compounds have numerous
clinically proven and potential therapeutic applications
such as for abortion, contraception, and in the treat-
ment of uterine leiomyomata, endometriosis, and breast
cancer.3
doses as an emergency contraceptive. However, due to
its glucocorticoid receptor (GR) antagonism, mifepri-
stone has compromised clinical applications (e.g., as a
long-term contraceptive agent).5 Since the discovery of
mifepristone, much effort has been made to optimize
Y
R
N
X
OH
N
O
O
O
O
1
3
2a X = F, Y = F, R = Et
2b X = Ac, Y = H, R = Et
2c X = Ac, Y = H, R = Me
2d X = Ac, Y = H, R = H
2e X = Me2N, Y = H, R = Et
2f X = Me2N, Y = H, R = Me
2g X = Me2N, Y = H, R = H
2h X = MeO, Y = F, R = Et
2i X = MeO, Y = F, R = Me
The first competitive PR antagonist, mifepristone (RU
486, 1, Fig. 1), was introduced by the Roussel-Uclaf
group.4 Mifepristone is currently used as an abortifa-
cient in the first 2 months of pregnancy and in smaller
O
Keywords: Steroidal spiro-oxazole; Progesterone receptor; Glucocor-
ticoid receptor; Antagonist; Selective progesterone receptor
modulators.
O
*
Corresponding authors. Tel.: +1 919 541 6328 (C.J.); fax: +1 919 541
6499; e-mail addresses: cjin@rti.org; jak@rti.org
Deceased.
Figure 1. Structures of mifepristone (1), steroidal spiro-oxazoles (2),
and ORG 33628 (3).
ꢀ
0960-894X/$ - see front matter Ó 2007 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2007.08.064

C. Jin et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5754–5757
5755
the antiprogestational effect with regard to the reduction
of antiglucocorticoid activity.6 At present few clinically
successful selective PR antagonists are available. We re-
cently developed a convenient synthesis of novel 11b-
aryl-40,50-dihydrospiro[estra-4,9-diene-17b,40-oxzole]s
(e.g., 2a; X = F; Y = F; R = Et) via copper(I)-catalyzed
cyclization of the corresponding acylaminoacetylenes7
as part of a research program to discover highly potent
antiprogestins with reduced endocrine side effects. These
novel spiro-oxazoles are structurally similar to the re-
ported 17,17-spirocyclic steroids (e.g., ORG 33628, 3),
which have been claimed to have enhanced antiproges-
tational effects, in some cases, with considerably reduced
antiglucocorticoid activities.8 Herein we report a series
of new 11b-aryl-40,50-dihydrospiro[estra-4,9-diene-
17b,40-oxazole] analogs (2b–i, Fig. 1) and their antago-
nist hormonal properties.
addition of 5 with the Grignard reagent, generated
from 4-bromo-2-fluoroanisole, led to the correspond-
ing 11b-aryl substituted compound 6 in 87% yield.10
Oxime formation with hydroxylamine hydrochloride
in pyridine provided 7. Crude 7, used without purifica-
tion, was treated with NBS to afford the 17-bromo-17-
nitro compound, which was readily reduced by
NaBH4 to give 8 in 78% yield.11 The introduction of
the 17a-ethynyl substituent in the C17-position was
achieved stereoselectively by treatment of the anion
of 8 in DMSO with ethynyllead(IV) triacetate to give
a 66% yield of 9.12,13 Reduction of 9 using zinc at 0 °C
gave the corresponding hydroxylamine, which upon
treatment with 2-mercaptoethyl ether and sodium tet-
raborate produced amine 10 in 70% yield.14 This
two-step reduction procedure is superior to the zinc
reduction at 70 °C, in which the ethynyl group was
also reduced to the ethene and 10 was obtained in
low yield. Deketalization and simultaneous dehydra-
tion of 10 with TFA provided dienone 11. Finally,
acylation with propionyl chloride or acetyl chloride
followed by cyclization7 using 10 mol % of CuI in
1:1 benzene/Et3N at 90 °C furnished spiro-oxazoles
2h and 2i in 80% and 42% yield, respectively. All syn-
thesized spiro-oxazoles 2b–i were P98% pure as deter-
mined by HPLC analyses. The 1H NMR spectra of
the compounds were in agreement with the assigned
structures.7,15
The synthesis of 11b-aryl-40,50-dihydrospiro[estra-4,9-
diene-17b,40-oxazole] analogs 2b–g was accomplished
following the previously reported procedures.7,9
Compounds 2h and 2i were prepared using the same
synthetic approach, outlined in Scheme 1, with some
modifications. Briefly, the regio-/stereo-selective
epoxidation of commercially available 3,3-[1,2-etha-
nediylbis(oxy)]estra-5(10),9(11)-dien-17-one (4) using
hexafluoroacetone trihydrate and hydrogen peroxide
gave epoxide 5 in 53% yield. Copper-catalyzed 1,4-
F
F
MeO
MeO
O
O
O
NOH
O
a
c
b
O
O
O
O
O
d
O
OH
6
O
OH
O
4
5
7
F
F
F
MeO
MeO
O
MeO
O
NO2
NO2
NH2
g
e
f
O
O
OH
O
OH
O
OH
8
9
10
F
F
F
O
R
MeO
MeO
O
MeO
O
NH2
HN
R
N
O
h
i
O
11
12h R = Et
12i R = Me
2h R = Et
2i R = Me
Scheme 1. Synthesis of 2h and 2i. Reagents and conditions: (a) CF3COCF3, Na2HPO4, H2O2, 0 °C; (b) 4-bromo-2-fluoroanisole/Mg, THF, CuI,
0 °C; (c) HONH2ÆHCl, pyridine, rt; (d) NBS, KHCO3, dioxane, H2O, rt, then NaBH4, rt; (e) Bu3SnCCH, Pb(OAc)4, rt, then 8/KOt-Bu/DMSO, rt;
(f) Zn, NH4Cl, 0 °C, then 2-mercaptoethyl ether, FeSO4(NH4)2SO4, Na2B4O7, 0.1 N HCl, reflux; (g) TFA, CH2Cl2, H2O, 0 °C; (h) propionyl chloride
or acetyl chloride, Et3N, 0 °C; (i) 10 mol % CuI, 1:1 benzene/Et3N, 90 °C.

5756
C. Jin et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5754–5757
Table 1. Antihormonal properties of spiro-oxazoles 2b–i
Y
R
X
N
O
O
Compound
Structure
Y
T47D (PR) and A549 (GR) activity
A549 IC50 (nM)
X
R
T47D IC50 (nM)
Ratio (GR/PR)
Mifepristone
0.054
0.34
0.59
82
6
110
620
780
171
24
2b
2c
2d
2e
2f
Ac
Ac
H
H
H
H
H
H
F
Et
210
460
14,000
23
Me
H
Ac
Me2N
Me2N
Me2N
MeO
MeO
Et
0.98
0.63
18
Me
H
82
130
30
2g
2h
2i
540
>10,000
660
Et
Me
1.0
4.6
>10,000
140
F
Compounds 2b–i were evaluated for PR antagonist
activity based on the ability to block promegestone
(R5020) induction of alkaline phosphatase activity in
the human breast cancer cell line T47D.6e Their GR
antagonist activity was also tested on the ability to inhi-
bit corticoid-induced transcription from a glucocorti-
coid response element (GRE)-linked luciferase reporter
gene in the human lung carcinoma cell line A549.6e
The IC50 values of the tested compounds from the
T47D and A549 assays are listed in Table 1. The ratio
of the A549 IC50 to the T47D IC50 was also calculated
as a measure of the separation of PR and GR antago-
nism. The commercial drug mifepristone was tested as
a control.
Marked reduction in the potency was observed by sub-
stitution of an 11b-(4-acetophenyl) group for 4-N,N-
dimethylaminophenyl. In terms of selectivity, all 11b-
(4-acetophenyl) substituted compounds (2b–d) show
greater separation of antiprogestational and antigluco-
corticoid activity compared to mifepristone, while the
11b-(4-N,N-dimethylaminophenyl) compounds (2e–g)
have similar or less selectivity than mifepristone. Com-
pounds 2b and 2c are 6- and 7-fold, respectively, more
selective than mifepristone with subnanomolar poten-
cies for PR. The best selectivity in differentiating PR
from GR was realized when R = Et with the 3-fluoro-
4-methoxyphenyl group at the 11-position (2h). This
compound has nanomolar potency (IC50 1.0 nM) as a
PR antagonist and shows no activity in the A549 assay
for GR agonism or antagonism at the tested
concentrations.
In the T47D assay, all the tested compounds are potent
progesterone receptor antagonists, with nanomolar
IC50 values (2d and 2g–i) or subnanomolar IC50 values
(2b, 2c, 2e, and 2f). However, none of the compounds
is as potent as mifepristone (IC50 0.054 nM). The 11b-
(4-acetophenyl) substituted compounds (2b and 2c) are
more potent than the compounds (2e and 2f) with a
11b-(4-N,N-dimethylaminophenyl) substitution, which
is consistent with the findings that replacement of the
11b-(4-N,N-dimethylaminophenyl) substituent in the
mifepristone derivatives with the 11b-(4-acetophenyl)
moiety increases the relative binding affinity for the
PR.16 For the same 11-substitution, the compounds
with R = Et and Me have higher potency than the
R = H compound. The most potent compound in the
series was achieved when R = Et with the 11b-(4-ace-
tophenyl) substituent (2b). It is interesting to note that
both of 2d and 2g (R = H) have the highest affinity for
PR in the competitive binding assay (data not shown).
The low potency of 2d and 2g in the T47D assay, as
well as in the A549 assay, is presumably due to the
instability of the spiro-oxazole moiety of these
compounds.
In conclusion, a series of novel 11b-aryl-40,50-dihydro-
spiro[estra-4,9-diene-17b,40-oxazole] analogs have been
synthesized in a 10-step sequence from commercially
available 3,3-[1,2-ethanediylbis(oxy)]-estra-5(10),9(11)-
dien-17-one (4). Some of the compounds (2b, 2c, and
2h) demonstrated high potency and a better selectivity
profile in the separation of antiprogestational and
antiglucocorticoid activity than mifepristone. These
novel steroidal spiro-oxazoles are promising leads for
further investigation of highly potent and selective
antiprogestins.
Acknowledgment
This work was supported by the R.W. Johnson Pharma-
ceutical Research Institute.
References and notes
In the A549 assay, all compounds are less potent than
mifepristone, with IC50 values greater than 23 nM.
1. Spitz, I. M.; Chwalisz, K. Steroids 2000, 65, 807.
2. Spitz, I. M. Steroids 2003, 68, 981.

C. Jin et al. / Bioorg. Med. Chem. Lett. 17 (2007) 5754–5757
5757
3. (a) Klijn, J. G.; Setyono-Han, B.; Foekens, J. A. Steroids
2000, 65, 825; (b) Chabbert-Buffet, N.; Meduri, G.;
Bouchard, P.; Spitz, I. M. Hum. Reprod. Update 2005,
11, 293; (c) Chwalisz, K.; Perez, M. C.; DeManno, D.;
Winkel, C.; Schubert, G.; Elger, W. Endocr. Rev. 2007, 26,
423.
Schoonen, W. G. Ann. N.Y. Acad. Sci. 1995, 761, 192;
(c) Rao, P. N.; Wang, Z. Q.; Cessac, J. W.; Rosenberg, R.
S.; Jenkins, D. J. A.; Diamandis, E. P. Steroids 1998, 63,
523; (d) Cook, C. E.; Kepler, J. A.; Shetty, R. S.; Bartley,
G. S.; Lee, D. Y.-W. U.S. Patent 5,962,444, 1999; Chem.
Abstr. 1999, 131, 243468; (e) Cook, C. E.; Shetty, R. S.;
Kepler, J. A.; Lee, D. Y.-W. U.S. Patent 6,043,235, 2000;
Chem. Abstr. 2000, 132, 237245; (f) Kloosterboer, H. J.;
Deckers, G. H.; Schoonen, W. G.; Hanssen, R. G.; Rose,
U. M.; Verbost, P. M.; Hsiu, J. G.; Williams, R. F.;
Hodgen, G. D. Steroids 2000, 65, 733.
4. Teutsch, G.; Philibert, D. Hum. Reprod. 1994, 9(1), 12.
5. (a) Agarwai, M. K. Pharmacol. Ther. 1996, 70, 183;
(b) Tang, O. S.; Ho, P. C. Gynecol. Endocrinol. 2006, 22, 655.
6. (a) Wehle, H.; Moll, J.; Cato, A. C. B. Steroids 1995, 60,
368; (b) Wagner, B. L.; Pollio, G.; Giangrande, P.;
Webster, J. C.; Breslin, M.; Mais, D. E.; Cook, C. E.;
Vedeckis, W. V.; Cidlowski, J. A.; McDonnell, D. P.
Endocrinology 1999, 140, 1449; (c) Fuhrmann, U.; Hess-
Stumpp, H.; Cleve, A.; Neef, G.; Schwede, W.; Hoffmann,
J.; Fritzemeier, K. H.; Chwalisz, K. J. Med. Chem. 2000,
43, 5010; (d) Cook, C. E.; Raje, P.; Lee, D. Y.-W.; Kepler,
J. A. Org. Lett. 2001, 3, 1013; (e) Jiang, W. Q.; Allan, G.;
Fiordeliso, J. J.; Linton, O.; Tannenbaum, P.; Xu, J.; Zhu,
P. F.; Gunnet, J.; Demarest, K.; Lundeen, S.; Sui, Z. H.
Bioorg. Med. Chem. 2006, 14, 6726; (f) Jiang, W. Q.;
Allan, G.; Chen, X.; Fiordeliso, J. J.; Linton, O.;
Tannenbaum, P.; Xu, J.; Zhu, P. F.; Gunnet, J.; Demarest,
K.; Lundeen, S.; Sui, Z. H. Steroids 2006, 71, 949;
(g) Kang, F. A.; Allan, G.; Guan, J. H.; Nareshkumar, J.;
Linton, O.; Tannenbaum, P.; Xu, J.; Zhu, P. F.; Gunnet,
J.; Chen, X.; Demarest, K.; Lundeen, S.; Sui, Z. H. Bioorg.
Med. Chem. Lett. 2007, 17, 907; (h) Kang, F. A.; Guan, J.
H.; Jain, N.; Allan, G.; Linton, O.; Tannenbaum, P.;
Chen, X.; Xu, J.; Zhu, P. F.; Gunnet, J.; Demarest, K.;
Lundeen, S.; Sui, Z. H. Bioorg. Med. Chem. Lett. 2007, 17,
2531.
9. Cook, C. E.; Kepler, J. A.; Bartley, G. S.; Shetty, R. S.
W.O. Patent 9,962,928, 1999; Chem. Abstr. 1999, 132,
23141.
10. Teutsch, G.; Klich, M.; Bouchoux, F.; Cerede, E.;
Philibert, D. Steroids 1994, 59, 22.
11. Patchett, A. A.; Hoffman, F.; Giarrusso, F. F.; Schwam,
H.; Arth, G. E. J. Org. Chem. 1962, 27, 3822.
12. Moloney, M. G.; Pinhey, J. T.; Roche, E. G. J. Chem. Soc.
Perkin Trans. 1989, 1, 333.
13. The stereochemistry at C17-position was assigned based
on comparison of its NMR spectra with that of known
compounds and was further confirmed according to the
NMR studies of spiro-oxazoles 2.
14. Nambu, Y.; Kijima, M.; Endo, T.; Okawara, M. J. Org.
Chem. 1982, 47, 3066.
1
15. 2h: H NMR (300 MHz; CDCl3) d 0.63 (s, 3H), 1.24 (t,
J = 7.5 Hz, 3H), 1.40–1.60 (m, 2H), 1.65–1.88 (m, 4H),
1.90–2.10 (m, 2H), 2.20–2.72 (m, 10H), 3.86 (s, 3H), 4.20
(d, J = 3.0 Hz, 1H), 4.27 (d, J = 6.0 Hz, 1H), 4.80 (d,
J = 3.0 Hz, 1H), 5.78 (s, 1H), 6.75–6.90 (m, 3H); 2i: 1H
NMR (300 MHz; CDCl3) d 0.62 (s, 3H), 1.40–1.58 (m,
2H), 1.68–1.86 (m, 4H), 1.90–2.10 (m, 2H), 2.11 (s, 3H),
2.20–2.75 (m, 8H), 3.86 (s, 3H), 4.21 (d, J = 3.0 Hz, 1H),
4.27 (d, J = 6.0 Hz, 1H), 4.80 (d, J = 3.0 Hz, 1H), 5.78 (s,
1H), 6.75–6.91 (m, 3H).
7. Jin, C. Y.; Burgess, J. P.; Kepler, J. A.; Cook, C. E. Org.
Lett. 2007, 9, 1887.
8. (a) Philibert, D.; Hardy, M.; Gaillard-Moguilewsky, M.;
´ ´
Nique, F.; Tournemine, C.; Nedelec, L. J. Steroid
Biochem. 1989, 34, 413; (b) Kloosterboer, H. J.; Deckers,
G. H.; de Gooyer, M. E.; Dijkema, R.; Orlemans, E. O.;
16. Wiechert, R.; Neef, G. J. Steroid biochem. 1987, 27,
851.