Bioorganic & Medicinal Chemistry 22 (2014) 5329–5337

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Development of p-carborane-based nonsteroidal progesterone receptor antagonists Shinya Fujii a,b, Eiichi Nakano a, Naoki Yanagida a, Shuichi Mori a, Hiroyuki Masuno a, Hiroyuki Kagechika a,⇑ a b

Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, 2-3-10 Kanda-Surugadai, Chiyoda-ku, Tokyo 101-0062, Japan Institute of Molecular and Cellular Biosciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032, Japan

a r t i c l e

i n f o

Article history: Received 14 July 2014 Revised 28 July 2014 Accepted 29 July 2014 Available online 7 August 2014 Keywords: Progesterone Nuclear receptor Antagonist Carborane Nonsteroid

a b s t r a c t Progesterone receptor (PR) regulates various physiological processes, including the female reproductive system, and development of nonsteroidal PR antagonists is considered desirable for clinical application, as they are expected to have reduced side effects. We have synthesized a series of nonsteroidal PR antagonists using a 4-cyanophenyl-p-carborane core structure. Among them, compound 14d exhibited potent PR-antagonistic activity (IC50: 27 nM). It showed high binding affinity for PR, but did not bind to androgen receptor or estrogen receptor. This PR-selective antagonist may be a promising lead compound for clinically applicable progesterone receptor modulators. Ó 2014 Elsevier Ltd. All rights reserved.

1. Introduction Progesterone receptor (PR) is a member of the nuclear receptor superfamily of ligand-inducible transcription factors1 and plays essential roles in many physiological processes, including regulation of uterine cell proliferation/differentiation, implantation, ovulation, and mammary gland growth/differentiation.2–5 Several synthetic PR agonists have been developed for clinical use in contraception, hormone replacement therapy to reduce estrogenmediated endometrial cancer risk, and treatment of gynecological disorders.6–8 In order to avoid side effects due to cross-activity with other nuclear steroid receptors, development of nonsteroidal PR agonists has been investigated. A benzoxazine-2-thione derivative, tanaproget (2), is a representative nonsteroidal PR agonist that is expected to enter clinical use.9 On the other hand, little work has yet been done on potential clinical applications of PR antagonists. Mifepristone (RU486: 3) is the most extensively investigated steroidal PR antagonist, and is used to induce abortion.10 However, investigation of 3 has suggested that PR antagonists might be effective not only as contraceptive agents, but also in the treatment of endometriosis,11 uterine leiomyoma,12 and breast cancer.13,14 Therefore development of potent and selective nonsteroidal PR antagonists is desirable for detailed investigation of the ⇑ Corresponding author. Tel.: +81 3 5280 8032; fax: +81 3 5280 8127. E-mail address: [email protected] (H. Kagechika). http://dx.doi.org/10.1016/j.bmc.2014.07.049 0968-0896/Ó 2014 Elsevier Ltd. All rights reserved.

pharmaceutical potential of PR modulation, and indeed, several nonsteroidal PR antagonists such as 4 and 5 have been developed based on the structure of 2 (Fig. 1). We recently reported the development of a novel nonsteroidal PR-selective antagonist 9 bearing a carborane cage as a hydrophobic pharmacophore.15 Carboranes (6–8) (dicarba-closo-dodecaboranes; Fig. 2) are icosahedral carbon-containing boron clusters that have a bulky spherical structure with high hydrophobicity, as well as high thermal and chemical stability.16,17 We have previously applied the carborane cage as a hydrophobic pharmacophore for nuclear receptor ligands, and developed novel carborane-based ligands for vitamin D receptor (VDR),18,19 androgen receptor (AR),20,21 and estrogen receptor (ER).22,23 Among the nuclear receptors, PR ligand-binding domain (LBD) shows the highest sequence identity with AR LBD: there is 55% sequence identity between AR LBD and PR LBD,24 and 87% sequence similarity. Therefore the three-dimensional structures of these two LBDs are very similar.25 On the basis of these considerations, we hypothesized that our carborane-based AR antagonists20,21 might also exhibit PR-antagonistic activity, and that structural development could lead to a novel type of PR-selective antagonists having characteristic structural features different from those of 9 and other reported PR antagonists. Herein, we report the development of potent PR antagonists by using carborane-based AR antagonists as lead compounds.

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Figure 3. Our developed AR antagonists bearing a p-carborane cage and their PRantagonistic activity. aDetermined by alkaline phosphatase assay with 1 nM progesterone. bInduction of alkaline phosphatase at a concentration of 10 lM. c Competitive binding using hAR-LBD and 4 nM [3H]DHT. dInhibition was not detected at the concentration of 10 lM.

Figure 1. Structures of PR ligands.

Docking simulation using AR-LBD and 10 suggested that T877 forms a hydrogen bond to the hydroxyl group of 10.27 It has also been reported that C891 of PR interacts with the acetyl group of progesterone.28 Therefore we hypothesized that partial structure interacting with Thr877 or Cys891 is essential for activity and selectivity of ligands for AR and PR. Based on these considerations, we designed 4-cyanophenylcarborane derivatives 13–16 bearing different substituents at the carbon atom of the p-carborane cage (Fig. 4). 2.2. Synthesis

2. Results and discussion

Preparation of 4-cyanophenyl-p-carborane derivatives 13–16 is shown in Scheme 1. Ullman-type coupling of C-lithiated p-carborane29 with 4-iodobenzonitrile gave 4-cyanophenyl-p-carborane (12). Reaction of C-lithiated 12 with various aldehydes gave the corresponding secondary alcohols 13a–f. Oxidation of alcohol 13a–f with Dess–Martin periodinane gave ketones 14a–f. Reaction of C-lithiated 12 with epoxides gave corresponding secondary alcohols bearing a methylene group between the carborane cage and the alcohol moiety (15a,b,f). Compounds 15a,b,f were oxidized to ketones 16a,b,f with Dess–Martin periodinane (Scheme 1). 3-Cyanophenyl derivative 19 and compounds 25–27 bearing functionalities other than cyano groups were also synthesized. Compound 19 was synthesized by a similar method to that used for preparation of 4-cyano isomer 14d. Compounds bearing nitro, methoxy and trifluoromethyl groups were prepared by Ullmanntype coupling using compound 21 and corresponding iodobenzenes followed by deprotection of TBS and oxidation (Scheme 2).

2.1. Molecular design

2.3. PR-antagonistic activity

First, we investigated the PR-antagonistic activity of our previously developed carborane-based AR antagonists by means of alkaline phosphatase assay using human breast cancer cell line T-47D, which endogenously expresses PR.26 3-Cyanophenyl-pcarborane derivative BA341 (10) exhibited potent PR-antagonistic activity, as we had hoped. The 4-cyanophenyl isomer BA331 (11) also exhibited PR-antagonistic activity. Our previous work on AR antagonists had shown that the 3-cyanophenylcarborane scaffold is preferable to the 4-cyano isomer for AR-antagonistic activity.20 In addition, compound 10 exhibited PR agonistic activity at high concentrations. Therefore we chose 4-cyanophenylcarborane derivative 11 as a lead compound to develop PR-selective full antagonists (Fig. 3). As mentioned above, PR-LBD shares high sequence identity with AR-LBD. Among the key amino acids that form hydrogen bonds with ligands, two are identical in PR and AR. The major difference is cysteine (C891in PR) and threonine (T877 in AR).

PR-agonistic and antagonistic activities of synthesized compounds were evaluated by means of T-47D alkaline phosphatase assay.26 None of the synthesized compounds exhibited PR-agonistic activity (data not shown). Table 1 shows the activities of 4-cyanophenylcarborane derivatives 13a–f and 14a–f, compared to that of the lead compound 11. Alcohols 13a–f bearing a small hydrophobic substituent exhibited potent PR-antagonistic activity, whereas introduction of a large substituent such as n-pentyl (13e) or phenyl (13f) significantly reduced the antagonistic activity. Compound 13d bearing a cyclopropyl group exhibited the most potent antagonistic activity among the alcohols. Regarding ketones 14a–f, the structure–activity relationship of the hydrophobic substituents was similar to that of alcohols, namely a small hydrophobic substituent was preferable to a large substituent as a hydrophobic substructure. Ethyl ketone 14b and cyclopropyl ketone 14d exhibited the most potent activity with an IC50 value of 27 nM (Table 1).

Figure 2. Structures of carboranes and our previously developed PR antagonist 9 bearing a 1,7-diphenyl-m-carborane scaffold.

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Figure 4. Design scheme of novel PR antagonists. (A) Putative binding mode of BA341 (10) to AR. (B) Designed PR antagonists 13–16 based on 4-cyanophenyl-p-carborane core structure.

Scheme 1. Synthesis of designed compounds based on a 4-cyanophenyl-p-carborane core. Reagents and conditions: (a) n-BuLi, CuCl, pyridine, 4-iodobenzonitrile, DME, 67%; (b) LDA, aldehyde, THF, 12–78%; (c) Dess–Martin periodinane, CH2Cl2, 65–92%; (d) LDA, epoxide, THF, 36–60%; (e) Dess–Martin periodinane, CH2Cl2, 75–90%.

Scheme 2. Synthesis of compounds bearing a cyclopropyl ketone moiety. Reagents and conditions: (a) n-BuLi, CuCl, pyridine, 3-iodobenzonitrile, DME, 75%; (b) LDA, cyclopropanecarboxaldehyde, THF, 26%; (c) Dess–Martin periodinane, CH2Cl2, 79%; (d) n-BuLi, cyclopropanealdehyde, THF, 95%; (e) TESOTf, 2,6-lutidine, CH2Cl2, quant; (f) nBuLi, CuCl, pyridine, iodobenzene, DME; (g) HCl, THF–MeOH–H2O, 22–44% for 2 steps; (h) Dess–Martin periodinane, CH2Cl2, 61–90%.

Table 2 shows the activity of compounds 15a–f and 16a–f, in which one methylene group was introduced between the carborane cage and alcohol carbon or carbonyl group of 13 and 14. Though the alcohol 15a exhibited potent PR-antagonistic activity, the other compounds exhibited weaker activities than the corresponding one-carbon-shorter compounds. These results suggest that introduction of a methylene group is unfavorable (Table 2). Next, we investigated the role of the 4-cyano group. 4-Nitro derivative 25 exhibited potent activity, comparable to that of 14d. This result is consistent with reported structure–activity relationship studies of PR and AR ligands, indicating that a nitro group as well as a cyano group can function as a pharmacophore

corresponding to the 3-carbonyl group of progesterone or testosterone. 3-Cyanophenyl compound 19 exhibited lower activity than compound 14d bearing a 4-cyano group, and replacement of the cyano group with a methoxy or trifluoromethyl group resulted in significant loss of activity. The structure–activity relationship study revealed that a 4-cyanophenyl-p-carborane scaffold is favorable for PR antagonists (Table 3). Finally, we examined the binding affinity of cyclopropane derivatives 13d and 14d, which exhibited potent PR-antagonistic activity. The binding affinities were evaluated using the receptor LBD and radiolabelled ligands (Table 4). Both compounds exhibited binding affinity toward PR. This result suggests that the

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Table 1 PR-antagonistic activity of 4-cyanophenylcarborane derivatives 13a–f and 14a–f determined by means of T-47D alkaline phosphatase assaya

X

R

NC

a

Compound

X

R

IC50 (nM)

3 11 13a 13b 13c 13d 13e 13f 14a 14b 14c 14d 14e 14f

— CHAOH CHAOH CHAOH CHAOH CHAOH CHAOH CHAOH C@O C@O C@O C@O C@O C@O

— H Me Et i-Pr Cyclopropyl n-Pentyl Ph Me Et i-Pr Cyclopropyl n-Pentyl Ph

0.2 60 98 63 98 37 660 420 75 27 29 27 770 230

Expression of alkaline phosphatase was induced with 1 nM progesterone.

Table 2 PR-antagonistic activity of synthesized compounds determined by means of T-47D alkaline phosphatase assaya

X

R

NC

a

Compound

X

R

IC50 (nM)

15a 15b 15f 16a 16b 16f

CHAOH CHAOH CHAOH C@O C@O C@O

Me Et Ph Me Et Ph

32 83 520 150 190 370

Expression of alkaline phosphatase was induced with 1 nM progesterone.

Table 3 PR-antagonistic activity of synthesized cyclopropyl ketone derivativesa

Figure 5. Docking model of p-carborane derivative 14d with hPR LBD and AR LBD by a docking program AutoDock. (A) Docking model of 14d with hPR LBD. (B) Superimposition of hPR LBD binding to progesterone (purple) and docking model of 14d is displayed. (C) Superimposition of AR LBD binding to DHT (PDB ID: 1I37)31 (blue) and docking model of 14d is displayed. Hydrogen bonds of DHT (light blue) and of 14d (purple) were also indicated.

O

3

R 4

a

Compound

R

IC50 (nM)

14d 19 25 26 27

4-CN 3-CN 4-NO2 4-OCH3 4-CF3

27 78 35 1200 1200

Expression of alkaline phosphatase was induced with 1 nM progesterone.

PR-antagonistic activity of these compounds in T-47D alkaline phosphatase assay was indeed mediated by binding of the compounds with PR. In addition, alcohol 13d exhibited significant binding affinity toward AR, whereas cyclopropyl ketone 14d did not. These results suggest that PR can accept an alcoholic hydroxyl group as well as a carbonyl group as the hydrophilic pharmacophore of its ligands, and that selectivity for PR over AR is at least partly dependent on this difference. Neither of the compounds exhibited any detectable affinity for ER. Thus, 14d is novel type of potent PR-selective antagonist (Table 4).

Table 4 Binding affinities of selected compounds 13d and 14d toward PR, AR and ER Compound 13d 14d a b c d

PR bindinga IC50 (M) 3.4  10 4.8  10

7 7

The concentration of [3H]progesterone was 4 nM. The concentration of [3H]DHT was 4 nM. The concentration of [3H]estradiol was 1 nM. No detectable binding was observed.

AR bindingb IC50 (M) 4.5  10 N.D.d

7

ER bindingc IC50 (M) N.D.d N.D.d

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In order to understand the receptor selectivity of compound 14d, docking simulation using the co-crystal structures of hPR LBD with progesterone (PDB ID: 1A28)28 and hAR LBD with R1881 (PDB ID: 1E3G)30 was performed. Figure 5A shows the docking model of compound 14d with PR LBD, and Figure 5B shows its superimposition with co-crystal structure of progesterone. In the calculated structure, 4-cyano group of 14d interacts with Gln725 and Arg766 residues that interact with 3-carbonyl group of progesterone. Carbonyl group of 14d interacts with Cys891 and Thr894 that interact with 20-carbonyl group of progesterone. On the other hand, in the calculated structure of 14d docked with AR LBD (Fig. 5C), the cyano group of 14d interacts with Gln711 and Arg752 that interact with 3-carbonyl group of DHT, while carbonyl group of compound 14d could not interact with Asn705 or Thr877 that interact with 17-hydroxyl group of DHT. The difference of binding mode is possible reason of PR selectivity of compound 14d over AR (Fig. 5). 3. Conclusion We synthesized various phenyl-p-carborane derivatives as candidate nonsteroidal PR antagonists by using AR antagonist 11 as a lead compound. Biological evaluation revealed that the 4-cyanophenyl-p-carborane core structure functions as a versatile scaffold for PR antagonists. Structural development and structure–activity relationship studies suggested that a small substituent was preferable to a large substituent as the hydrophobic substructure, and also that the nature of the hydrophilic pharmacophore is critical for PR selectivity. Among the compounds synthesized, 14d exhibited potent PR-antagonistic activity and high binding affinity for PR, with high selectivity for PR over AR and ER. The present results are expected to contribute to clinical development of PR antagonists. 4. Experimental section 4.1. Chemistry All reagents were purchased from Sigma–Aldrich Chemical Co., Tokyo Kasei Kogyo Co., Wako Pure Chemical Industries, and Kanto Chemical Co., Inc. NMR spectra were recorded on Bruker AVANCE 400 or AVANCE 500 spectrometers. Chemical shifts are reported in ppm as d values from tetramethylsilane. Data are reported as follows: chemical shift, multiplicity (s, singlet; d, doublet; t, triplet; q quartet; br, broad; m, multiplet), coupling constants (Hz), integration. Mass spectra were collected on Bruker Daltonics microTOF-2focus or JEOL AX505H in the positive and negative ion modes. Melting points were obtained on a Yanagimoto micro melting point apparatus without correction. 4.2. Synthesis 4.2.1. 1-(4-Cyanophenyl)-1,12-dicarba-closo-dodecaborane (12) Under an Ar atmosphere, n-BuLi (1.55 mol/L in n-hexane, 9.9 mL, 15.26 mmol) was added dropwise to a solution of p-carborane (1.95 g, 13.52 mmol) in 1,2-dimethoxyethane (15 mL) at 0 °C. The reaction mixture was stirred at room temperature for 30 min, and then copper(I) chloride (1.73 g, 17.52 mmol) was added to the reaction vessel. The reaction mixture was stirred for 1.5 h, then pyridine (6 mL) and 4-iodobenzonitrile (3.44 g, 15.04 mmol) were added and stirring was continued overnight at 80 °C. The reaction mixture was cooled to room temperature, then diluted with diethyl ether and filtered through Celite. The filtrate was washed with 5% aqueous solution of sodium thiosulfate, 2 M hydrochloric acid, water and brine, then dried over sodium sulfate and evaporated. The crude product was purified by flash silica gel column chromatography (eluent; n-hexane/dichloromethane 10:1)

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to afford 2.23 g of 2–3 (9.09 mmol, 67%). 1H NMR (500 MHz, CDCl3) d 7.48 (dt, J = 8.6, 1.9 Hz, 2H), 7.32 (dt, J = 8.6, 1.9 Hz, 2H), 2.97– 1.83 (m, 11H). 4.2.2. General procedure for preparation of compounds 13a–f To a solution of 12 (100 mg, 0.408 mmol) in THF (0.37 mL) was added LDA (1.08 mol/L in n-hexane-THF, 415 lL, 0.448 mmol) at 78 °C under Ar. The mixture was stirred at 78 °C for 30 min, then the corresponding aldehyde (1.0–10 equiv) was added at 78 °C. Stirring was continued at 78 °C for 30 min, and the mixture was poured into aqueous NH4Cl, and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4, and then concentrated. Purification by silica gel column chromatography (eluent; hexane/AcOEt) gave the desired compounds 13a–f. 4.2.3. 1-(4-Cyanophenyl)-12-(1-hydroxyethyl)-1,12-dicarbacloso-dodecaborane (13a) White solid (72% yield): 1H NMR (500 MHz, CDCl3) d 7.46 (dd, J = 8.7, 1.9, 1.9 Hz, 2H), 7.30 (ddd, J = 8.6, 2.0, 1.7 Hz, 2H), 3.73 (qd, J = 6.3, 6.3 Hz, 1H), 3.10–1.80 (br m, 10H), 1.65 (d, J = 5.9 Hz, 1H), 1.10 (d, J = 6.4 Hz, 3H). 4.2.4. 1-(4-Cyanophenyl)-12-(1-hydroxypropyl)-1,12-dicarbacloso-dodecaborane (13b) White solid (71% yield): 1H NMR (500 MHz, CDCl3) d 7.46 (dd, J = 8.7, 2.0, 1.9 Hz, 2H), 7.30 (dd, J = 8.7, 2.0 Hz, 2H), 3.40–3.34 (m, 1H), 3.10–1.80 (br m, 10H), 1.68–1.62 (m, 1H), 1.51–1.42 (m, 1H), 1.20–1.10 (m, 1H), 0.89 (t, J = 7.3 Hz, 3H). 4.2.5. 1-(4-Cyanophenyl)-12-(1-hydroxy-2-methylpropyl)-1,12dicarba-closo-dodecaborane (13c) White solid (75% yield): 1H NMR (500 MHz, CDCl3) d 7.46 (ddd, J = 8.6, 2.0, 1.8 Hz, 2H), 7.30 (ddd, J = 8.6, 1.9, 1.8 Hz, 2H), 3.40 (dd, J = 7.1, 1.3 Hz, 1H), 3.10–1.80 (br m, 10H), 1.72 (m, 1H), 1.57 (d, 1H, J = 7.1 Hz), 0.91 (d, J = 6.9 Hz, 3H), 0.78 (d, J = 6.6 Hz, 3H). 4.2.6. 1-(4-Cyanophenyl)-12-(cyclopropylhydroxymethyl)-1,12dicarba-closo-dodecaborane (13d) White solid (12% yield): Recrystallized from hexane. Mp: 149.6– 152.1 °C; 1H NMR (400 MHz, CDCl3) d 7.48 (d, J = 8.7 Hz, 2H), 7.33 (d, J = 8.7 Hz, 2H), 3.3–1.6 (br m, 10H), 2.86 (dd, J = 8.2, 4.9 Hz, 1H), 1.66 (d, J = 4.9 Hz, 1H), 0.82–0.75 (m, 1H), 0.63–0.55 (m, 1H), 0.55– 0.49 (m, 1H), 0.34–0.25 (m, 2H); 13C NMR (125 MHz, CDCl3) d 141.1, 132.0, 128.2, 118.2, 112.6, 17.9, 5.0, 3.2. 4.2.7. 1-(4-Cyanophenyl)-12-(1-hydroxyhexyl)-1,12-dicarbacloso-dodecaborane (13e) Colorless oil (14% yield): 1H NMR (500 MHz, CDCl3) d 7.46 (d, J = 8.4 Hz, 2H), 7.30 (d, J = 8.5 Hz, 2H), 3.45 (m, 1H), 3.10–1.80 (br m, 10H), 1.67 (d, J = 6.2 Hz, 1H), 1.45–1.10 (m, 6H), 0.91–0.85 (m, 2H), 0.85 (t, J = 7.1 Hz, 3H). 4.2.8. 1-(4-Cyanophenyl)-12-(a-hydroxybenzyl)-1,12-dicarbacloso-dodecaborane (13f) White solid (78% yield): 1H NMR (500 MHz, CDCl3) d 7.46–7.42 (m, 2H), 7.33–7.29 (m, 3H), 7.29–7.25 (m, 2H), 7.18–7.14 (m, 2H), 4.65 (d, J = 3.5 Hz, 1H), 3.10–1.70 (br m, 10H), 2.16 (d, 1H, J = 3.7 Hz). 4.2.9. General procedure for preparation of compounds 14a–f To a solution of compounds 13a–f in CH2Cl2 was added Dess– Martin periodinate (1.5 equiv) at 0 °C under Ar. The mixture was stirred at room temperature for 2 h, poured into mixture of saturated Na2S2O4 and aqueous NaHCO3, and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4, and

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then concentrated. Purification by silica gel column chromatography (eluent; hexane/AcOEt) gave the desired compounds 14a–f. 4.2.10. 1-Acetyl-12-(4-cyanophenyl)-1,12-dicarba-closododecaborane (14a) White solid (92% yield): 1H NMR (500 MHz, CDCl3) d 7.49–7.45 (m, 2H), 7.30–7.26 (m, 2H), 3.10–1.90 (br m, 10H), 2.09 (s, 3H). 4.2.11. 1-(4-Cyanophenyl)-12-(propionyl)-1,12-dicarba-closododecaborane (14b) White solid (91% yield): 1H NMR (500 MHz, CDCl3) d 7.50–7.45 (m, 2H), 7.31–7.27 (m, 2H), 3.20–1.90 (br m, 10H), 2.40 (q, J = 7.1 Hz, 2H), 0.93 (t, J = 7.1 Hz, 3H). 4.2.12. 1-(4-Cyanophenyl)-12-(isobutyryl)-1,12-dicarba-closododecaborane (14c) White solid (88% yield): 1H NMR (500 MHz, CDCl3) d 7.49–7.45 (m, 2H), 7.31–7.27 (m, 2H), 3.20–1.90 (br m, 10H), 2.89 (septet, J = 6.7 Hz, 1H), 0.96 (d, J = 6.7 Hz, 6H). 4.2.13. 1-(4-Cyanophenyl)-12-(cyclopropylcarbonyl)-1,12dicarba-closo-dodecaborane (14d) White solid (66% yield). Recrystallized from hexane. Mp: 157.2– 159.5 °C; 1H NMR (400 MHz, CDCl3) d 7.49 (d, J = 8.8 Hz, 2H), 7.32 (d, J = 8.8 Hz, 2H), 3.3–1.6 (br m, 10H), 2.10–2.04 (m, 1H), 1.01– 0.94 (m, 4H); 13C NMR (125 MHz, CDCl3) d 195.2, 140.9, 132.1, 128.1, 118.1, 112.9, 18.1, 13.7; HRMS(ESI+) Calcd for C13H19B10NONa [M+Na]+: 338.2292. Found 338.2301. 4.2.14. 1-(4-Cyanophenyl)-12-(1-hydroxyhexyl)-1,12-dicarbacloso-dodecaborane (14e) White solid (74% yield): 1H NMR (500 MHz, CDCl3) d 7.49–7.45 (m, 2H), 7.30–7.26 (m, 2H), 3.10–1.90 (br m, 10H), 2.36 (t, J = 7.2 Hz, 2H), 1.42 (quintet, J = 7.4 Hz, 2H), 1.28–1.19 (m, 2H), 1.18–1.11 (m, 2H), 0.84 (t, J = 7.2 Hz, 3H). 4.2.15. 1-Benzoyl-12-(4-cyanophenyl)-1,12-dicarba-closododecaborane (14f) White solid (92% yield): 1H NMR (500 MHz, CDCl3) d 7.50–7.45 (m, 3H), 7.49–7.46 (m, 2H), 7.38–7.34 (m, 2H), 7.31–7.28 (m, 2H), 3.20–1.90 (br m, 10H). 4.2.16. General procedure for preparation of compounds 15a,b,f To a solution of 12 (100 mg, 0.408 mmol) in THF (0.4 mL) was added LDA (1.08 mol/L in n-hexane-THF, 415 lL, 0.448 mmol) at 78 °C under Ar. The mixture was stirred at 78 °C for 30 min, then the corresponding epoxide (0.530 mmol) was added at 78 °C under Ar. The mixture was stirred at 78 °C for 4 h, poured into aqueous NH4Cl, and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4, and then concentrated. Purification by silica gel column chromatography (eluent; hexane/ AcOEt) gave 15a,b,f. 4.2.17. 1-(4-Cyanophenyl)-12-(2-hydroxypropyl)-1,12-dicarbacloso-dodecaborane (15a) White solid (60% yield): 1H NMR (500 MHz, CDCl3) d 7.47–7.43 (m, 2H), 7.31–7.27 (m, 2H), 3.70–3.60 (m, 1H), 3.20–1.90 (br m, 10H), 1.86–1.73 (m, 2H), 1.50–1.46 (m, 1H), 1.06 (d, J = 6.2 Hz, 3H). 4.2.18. 1-(4-Cyanophenyl)-12-(2-hydroxybutyl)-1,12-dicarbacloso-dodecaborane (15b) White solid (52% yield): 1H NMR (500 MHz, CDCl3) d 7.47–7.43 (m, 2H), 7.31–7.27 (m, 2H), 3.41–3.32 (m, 1H), 3.20–1.90 (br m, 10H), 1.84–1.72 (m, 2H), 1.50–1.45 (m, 1H), 1.35–1.25 (m, 2H), 0.84 (t, J = 7.4 Hz, 3H).

4.2.19. 1-(4-Cyanophenyl)-12-(2-hydroxy-2-phenethyl)-1,12dicarba-closo-dodecaborane (15f) White solid (36% yield): 1H NMR (500 MHz, CDCl3) d 7.48–7.43 (m, 2H), 7.33–7.29 (m, 2H), 7.31–7.22 (m, 3H), 7.22–7.18 (m, 2H), 4.53 (ddd, J = 10.6, 3.5, 2.3 Hz, 1H), 3.30–1.90 (br m, 10H), 2.13 (dd, J = 15.4, 9.6 Hz, 1H), 1.98 (dd, J = 15.4, 1.4 Hz, 1H), 1.87 (d, J = 3.3 Hz, 2H). 4.2.20. General procedure for preparation of compounds 16a,b,f To a solution of compounds 15a,b,f in CH2Cl2 was added Dess– Martin periodinate (1.3 equiv) at 0 °C under Ar. The mixture was stirred at room temperature for 6 h, poured into mixture of saturated Na2S2O4 and aqueous NaHCO3, and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4, and then concentrated. Purification by silica gel column chromatography (eluent; hexane/AcOEt) gave the desired compounds 16a,b,f. 4.2.21. 1-(4-Cyanophenyl)-12-(2-oxopropyl)-1,12-dicarba-closododecaborane (16a) White solid (90% yield): 1H NMR (500 MHz, CDCl3) d 7.47–7.43 (m, 2H), 7.30–7.26 (m, 2H), 3.10–1.90 (br m, 10H), 2.67 (s, 2H), 2.07 (s, 3H). 4.2.22. 1-(4-Cyanophenyl)-12-(2-oxobutyl)-1,12-dicarba-closododecaborane (16b) White solid (75% yield): 1H NMR (500 MHz, CDCl3) d 7.46–7.43 (m, 2H), 7.30–7.26 (m, 2H), 3.10–1.90 (br m, 10H), 2.64 (s, 2H), 2.33 (q, J = 7.2 Hz, 2H), 0.99 (t, J = 7.2 Hz, 3H). 4.2.23. 1-(4-Cyanophenyl)-12-(2-oxo-2-phenethyl)-1,12dicarba-closo-dodecaborane (16f) White solid (89% yield): 1H NMR (500 MHz, CDCl3) d 7.81–7.78 (m, 2H), 7.60–7.56 (m, 1H), 7.47–7.43 (m, 2H), 7.45–7.42 (m, 2H), 7.28–7.25 (m, 2H), 3.21 (s, 2H), 3.10–1.90 (br m, 10H). 4.2.24. 1-(3-Cyanophenyl)-1,12-dicarba-closo-dodecaborane (17) Under an Ar atmosphere, n-BuLi (1.59 mol/L in n-hexane, 14.4 mL, 22.9 mmol) was added dropwise to a solution of p-carborane (3.00 g, 20.8 mmol) in 1,2-dimethoxyethane (20 mL) at 0 °C. The reaction mixture was stirred at room temperature for 30 min, and then copper(I) chloride (2.68 g, 27.0 mmol) was added to the reaction vessel. The reaction mixture was stirred for 1 h, then pyridine (7 mL) and 3-iodobenzonitrile (5.24 g, 22.9 mmol) were added and stirring was continued overnight at 80 °C. The reaction mixture was cooled at room temperature, then diluted with diethyl ether and filtered through Celite. The filtrate was washed with 5% aqueous solution of sodium thiosulfate, 2 M hydrochloric acid, water and brine, then dried over sodium sulfate and evaporated. The crude product was purified by flash silica gel column chromatography (eluent; n-hexane/dichloromethane, 10:1) to afford 3.82 g of 17 (15.6 mmol, 75%) as a colorless solid. 1H NMR (500 MHz, CDCl3) d 7.51 (dt, J = 7.7, 1.3 Hz, 1H), 7.49 (t, J = 1.7 Hz, 1H), 7.45–7.42 (m, 1H), 7.31 (t, J = 7.8 Hz, 1H), 2.98–1.84 (m, 10H). 4.2.25. 1-(3-Cyanophenyl)-12-(cyclopropylhydroxymethyl)1,12-dicarba-closo-dodecaborane (18) A solution of LDA (1.14 M in n-hexane-THF, 0.57 mL, 0.65 mmol) was added to a solution of 17 (132 mg, 0.54 mmol) in THF (30 mL) at 78 °C under Ar. The mixture was stirred at 78 °C for 30 min, then cyclopropanecarboxyaldehyde (0.081 mL, 1.08 mmol) was added at 78 °C, and stirring was continued at 78 °C for 2 h. The reaction was quenched with aqueous NH4Cl and extracted with EtOAc. The organic layer was washed with water and brine, dried over sodium sulfate, and then concentrated.

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Purification by silica gel column chromatography (eluent; n-hexane/ethyl acetate, 10:1) gave 18 as a white solid (49% yield): 1H NMR (400 MHz, CDCl3) d 7.54–7.49 (m, 2H), 7.45 (ddd, J = 8.2, 2.0, 1.0 Hz, 1H), 7.31 (dt, J = 1.0, 8.0 Hz, 1H), 3.3–1.6 (m, 10H), 2.87 (dd, J = 8.2, 5.0 Hz, 1H), 1.67 (d, J = 5.0 Hz, 1H), 0.74–0.82 (m, 1H), 0.64–0.57 (m, 1H), 0.56–0.48 (m, 1H), 0.33–0.24 (m, 2H); 13 C NMR (125 MHz, CDCl3) d 137.9, 132.0, 131.7, 131.0, 129.2, 118.3, 112.7, 87.0, 81.5, 17.9, 5.0, 3.2.

intermediates bearing a TES group. Each intermediate was dissolved in methanol (1.0 mL) and THF (1.0 mL), and 2 M HCl (0.1 mL) was added to the solution. The mixture was stirred at room temperature for 2 h, then the mixture was diluted with water and extracted with EtOAc. The organic layer was washed with water and brine, dried over sodium sulfate, and then concentrated. Purification by silica gel column chromatography (eluent; n-hexane) gave the desired compounds 22–24.

4.2.26. 1-(3-Cyanophenyl)-12-(cyclopropylcarbonyl)-1,12dicarba-closo-dodecaborane (19) Compound 19 was prepared by oxidation of 18 with Dess–Martin periodinane by the same method used for preparation of 14a–f. Compound 18: colorless solid (78% yield): 1H NMR (400 MHz, CDCl3) d 7.56–7.52 (m, 1H), 7.49 (t, J = 1.6 Hz, 1H), 7.44 (ddd, J = 8.2, 2.0, 1.1 Hz, 1H), 7.32 (t, J = 8.0 Hz, 1H), 3.3–1.6 (m, 10H), 2.10–2.03 (m, 1H) , 1.03–0.93 (m, 4H); 13C NMR (125 MHz, CDCl3) d 195.3, 137.7, 132.3, 131.5, 130.8, 129.3, 85.2, 83.4, 18.1, 13.7.

4.2.30. 1-(4-Nitrophenyl)-12-(cyclopropylhydroxymethyl)-1,12dicarba-closo-dodecaborane (22) White solid (22% yield): 1H NMR (500 MHz, CDCl3) d 8.03 (d, J = 9.0 Hz, 2H), 7.40 (d, J = 9.0 Hz, 2H), 3.3–1.6 (br m, 10H), 2.86 (d, J = 8.3 Hz, 1H), 0.82–0.75 (m, 1H), 0.63–0.57 (m, 1H), 0.56–0.49 (m, 1H), 0.33–0.24 (m, 2H).

4.2.27. 1-Cyclopropylhydroxymethyl-1,12-dicarba-closododecaborane (20) To a solution of p-carborane (500 mg, 3.47 mmol) in THF (30 mL) was added a 1.67 M solution of n-BuLi in n-hexane (2.65 mL, 4.16 mmol) at 78 °C under Ar. The mixture was stirred at 78 °C for 30 min and then cyclopropanecarboxyaldehyde (0.52 mL, 6.94 mmol) was added to it at 78 °C. Stirring was continued at 78 °C for 4 h. The reaction was quenched with aqueous NH4Cl and the whole was extracted with EtOAc. The organic layer was washed with water and brine, dried over sodium sulfate, and then concentrated. Purification by silica gel column chromatography (eluent; n-hexane/EtOAc, 5:1) gave 20 as a white solid in 95% yield: 1H NMR (500 MHz, CDCl3) d 3.0–1.5 (br m, 10H), 2.76 (dd, J = 8.2, 5.0 Hz, 1H), 2.73 (br s, 1H), 1.61 (d, J = 5.0 Hz, 1H), 0.80–0.70 (m, 1H), 0.59–0.53 (m, 1H), 0.51–0.46 (m, 1H), 0.30–0.20 (m, 2H). 4.2.28. 1-(Triethylsilyloxycyclopropylmethyl)-1,12-dicarbacloso-dodecaborane (21) Triethylsilyl trifluoromethanesulfonate (1.02 mL, 4.53 mmol) was added to a solution of 20 (650 mg, 3.02 mmol) in THF (5.0 mL) at 0 °C under Ar, and the mixture was stirred at room temperature for 2 h. The reaction was quenched with water and the mixture was extracted with dichloromethane. The organic layer was washed with water and brine, dried over sodium sulfate, and then concentrated. Purification by silica gel column chromatography (eluent; n-hexane) gave compound 21 as a colorless oil (quant.). 1H NMR (500 MHz, CDCl3) d 3.1–1.5 (br m, 10H), 2.79 (d, J = 8.5 Hz, 1H), 2.71 (br s, 1H), 0.93 (t, J = 7.9 Hz, 9H), 0.77–0.68 (m, 1H), 0.56 (q, J = 7.9 Hz, 6H), 0.55–0.42 (m, 2H), 0.28–0.20 (m, 1H), 0.20–0.12 (m, 1H). 4.2.29. General procedure for preparation of compounds 22–24 Under an Ar atmosphere, n-BuLi (1.67 mol/L in n-hexane, 0.20 mL, 0.33 mmol) was added dropwise to a solution of 19 (100 mg, 0.304 mmol) in 1,2-dimethoxyethane (0.3 mL) at 0 °C. The reaction mixture was stirred at room temperature for 30 min, and then copper(I) chloride (39 mg, 0.395 mmol) was added. Stirring was continued for 1.5 h, then pyridine (0.2 mL) and the corresponding iodobenzene (0.334 mmol) were added and stirring was continued overnight at 85 °C. The reaction mixture was cooled at room temperature, then diluted with diethyl ether and filtered through Celite. The mixture was washed with 5% aqueous solution of sodium thiosulfate, 2 M hydrochloric acid, water and brine, then dried with sodium sulfate and evaporated. The crude product was purified by flash silica gel column chromatography (eluent; n-hexane/dichloromethane) to give the

4.2.31. 1-(4-Methoxyphenyl)-12-(cyclopropylhydroxymethyl)1,12-dicarba-closo-dodecaborane (23) White solid (44% yield): 1H NMR (400 MHz, CDCl3) d 7.11 (d, J = 9.0 Hz, 2H), 6.68 (d, J = 9.0 Hz, 2H), 3.74 (s, 3H), 3.3–1.7 (br m, 10H), 2.87 (dd, J = 8.2, 5.0 Hz, 1H), 1.64 (d, J = 5.0 Hz, 1H), 0.85– 0.77 (m, 1H), 0.61–0.55 (m, 1H), 0.55–0.48 (m, 1H), 0.33–0.24 (m, 2H). 4.2.32. 1-(4-Trifluoromethylphenyl)-12(triethylsilyloxycyclopropylmethyl)-1,12-dicarba-closododecaborane (24) White solid (32% yield): 1H NMR (400 MHz, CDCl3) d 7.43 (d, J = 8.4 Hz, 2H), 7.34 (d, J = 8.4 Hz, 2H), 3.3–1.7 (br m, 10H), 2.87 (dd, J = 8.3, 4.9 Hz, 1H), 1.67 (d, J = 4.9 Hz, 1H), 0.83–0.75 (m, 1H), 0.64–0.57 (m, 1H), 0.55–0.49 (m, 1H), 0.34–0.22 (m, 2H). 4.2.33. General procedure for preparation of compounds 25–27 To a solution of a starting material in CH2Cl2 was added Dess– Martin periodinate (1.3 equiv) at 0 °C under Ar. The mixture was stirred at room temperature for 6 h, then poured into mixture of saturated Na2S2O4 and aqueous NaHCO3, and extracted with AcOEt. The organic layer was washed with brine, dried over Na2SO4, and then concentrated. Purification by silica gel column chromatography (eluent; hexane/AcOEt) gave 25–27. 4.2.34. 1-(4-Nitrophenyl)-12-(1-hydroxycyclopropylmethyl)1,12-dicarba-closo-dodecaborane (25) White solid (90% yield): 1H NMR (400 MHz, CDCl3) d 8.14 (d, J = 9.1 Hz, 2H), 7.60 (d, J = 9.1 Hz, 2H), 3.3–1.6 (br m, 10H), 2.25– 2.18 (m, 1H), 1.07–1.02 (m, 2H), 0.91–0.86 (m, 2H); 13C NMR (125 MHz, CDCl3) d 195.3, 147.9, 142.6, 128.4, 123.5, 85.5, 83.8, 18.1, 13.8. 4.2.35. 1-(4-Methoxyphenyl)-12-(1hydroxycyclopropylmethyl)-1,12-dicarba-closo-dodeca-borane (26) White solid (61% yield): 1H NMR (400 MHz, CDCl3) d 7.11 (d, J = 9.0 Hz, 2H), 6.69 (d, J = 9.0 Hz, 2H), 3.75 (s, 3H), 3.3–1.7 (br m, 10H), 2.12–2.05 (m, 1H), 1.00–0.92 (m, 4H); 13C NMR (125 MHz, CDCl3) d 195.9, 159.9, 128.8, 128.3, 113.5, 85.7, 83.8, 56.0, 18.1, 13.5. 4.2.36. 1-(4-Trifluoromethylphenyl)-12-(1hydroxycyclopropylmethyl)-1,12-dicarba-closo-dodecaborane (27) White solid (77% yield): 1H NMR (400 MHz, CDCl3) d 7.45 (d, J = 8.4 Hz, 2H), 7.32 (d, J = 8.4 Hz, 2H), 3.3–1.6 (br m, 10H), 2.11–2.05 (m, 1H), 1.01–0.95 (m, 4H); 13C NMR (125 MHz, CDCl3) d 195.3, 140.6, 131.2, 128.8, 126.3, 124.9, 86.0, 85.0, 18.5, 13.7.

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4.3. Biology 4.3.1. Alkaline phosphatase assay T-47D breast-carcinoma cells were cultured in RPMI 1640 medium with 10% (v/v) fetal bovine serum and Penicillin–Streptomycin Mixed Solution. Cells were plated in 96-well plates at 1  104 cell/ well and incubated overnight (37 °C, 5% CO2 in air). After 24 h, cells were treated with fresh medium containing test compound in the presence or absence of progesterone (1 nM), and further incubated for 24 h. The medium was aspirated and the cells were fixed with 100 lL of 1.8% formalin (in PBS). The fixed cells were washed with PBS and 75 lL of assay buffer (1 mg/mL p-nitrophenol phosphate in diethanolamine water solution, pH 9.0, 2 mM MgCl2) was added. The mixture was incubated at room temperature with shielding from light for 2 h, and then the reaction was terminated by the addition of 100 lL of NaOH per well. The absorbance at 405 nm was measured. 4.3.2. hPR binding assay hPR-binding assay was performed using recombinant hPR-LBD purchased from Invitrogen. hPR-LBD was diluted with buffer (20 mM Tris–HCl, 300 mM NaCl, 1 mM EDTA, 5 mM DTT, pH 8.0) to 5 nM and 300 lL aliquots were incubated in the dark at 4 °C with 4 nM [1,2,6,7-3H]progesterone (Perkin Elmer) and reference or test compounds (dissolved in DMSO; final concentration of DMSO was 3%). Nonspecific binding was assessed by addition of a 200-fold excess of nonradioactive progesterone. After 24 h, 30 lL of Dextran T-70/c-globulin-coated charcoal suspension was added to the ligand/protein mixtures (1% activated charcoal, 0.05% c-globulin, 0.05% Dextran 70, final concentrations) and incubated at 4 °C for 5 min. The charcoal was removed by centrifugation for 5 min at 1300g, and the radioactivity of the supernatant was measured in Ultima Gold scintillation cocktail (Perkin Elmer) by using a liquid scintillation counter. All experiments were performed in duplicate. 4.3.3. hAR binding assay A hAR-LBD expression plasmid vector encoding GST-hARLBD (627-919 aa, EF domain) fusion protein under the lac promoter was transfected into Escherichia coli strain HB-101. An overnight culture (10 mL) of the bacteria was added to 1 L of LB medium and incubated at 27 °C until the optical density at 600 nm reached 0.6–0.7. Following the addition of IPTG to a concentration of 1 mM, incubation was continued for an additional 4.5 h. Cells were harvested by centrifugation at 4000g at 4 °C for 15 min and stored at 80 °C until use. All subsequent operations were performed at 4 °C. The bacterial pellet obtained from 40 mL of culture was resuspended in 1 mL of ice-cold TEGDM buffer (10 mM Tris–HCl pH 7.4, 1 mM EDTA, 10% glycerol, 10 mM DTT, 10 mM sodium molybdate). The suspension was subjected to sonication using 10  10 s bursts on ice, and crude GST-hARLBD fraction was prepared by centrifugation of the suspension at 12,000g for 30 min at 4 °C. The crude receptor fraction was diluted with buffer (20 mM Tris–HCl pH 8.0, 0.3 M KCl, 1 mM EDTA) to a protein concentration of 0.3– 0.5 mg/mL and used in binding assays as hAR-LBD fraction. Aliquots of the hAR-LBD fraction were incubated in the dark at 4 °C with [3H]DHT (PerkinElmer, 4 nM final concentration) and reference or test compounds (dissolved in DMSO, final concentration of DMSO was 2%). Nonspecific binding was assessed by addition of a 200-fold excess of nonradioactive DHT. After 18 h, a Dextran 70/c-globulin-coated charcoal suspension was added to the ligand/protein mixture (1% activated charcoal, 0.05% c-globulin, 0.05% Dextran, 70 final concentrations) and the whole was incubated at 4 °C for 10 min. The charcoal was removed by centrifugation for 5 min at 1300g, and the radioactivity of the supernatant was measured in Ultima Gold scintillation cocktail (Perkin Elmer)

by using a liquid scintillation counter. All experiments were performed in duplicate. 4.3.4. hER binding assay Recombinant human ER was purchased from Wako Pure Chemical Industries, Ltd. Bio-Gel HT hydroxylapatite (Bio-Rad, Hercules, CA) was washed five times with the buffer (50 mM Tris–HCl, 1 mM KH2PO4, pH 7.2). The hydroxylapatite slurry was adjusted to 50% (by volume) hydroxylapatite in the suspension. The ER was diluted with binding buffer (50 mM Tris, pH 7.5, 10% glycerol, 0.1 mM butylated hydroxyanisole, 10 mM mercaptoethanol, 0.5% yeast extract) to a protein concentration of 2–4 nM. Then 2 lL of 10 6 M [3H]estradiol solution in DMSO was added to each tube, followed by 2 lL aliquots of the competitor solutions in DMSO. After addition of 200 lL of ER solution to each tube, the tubes were placed in the refrigerator. The final incubation conditions were as follows: 10 8 M [3H]estradiol, 10 4–10 8 M competitor. After 14–18 h, the bound ligand was assayed by adsorption on hydroxylapatite for 15 min at 0 °C, followed by three washes with 1 mL of 0.05 M Tris, pH 7.3. After the last wash, the hydroxylapatite pellet was resuspended in 0.3 mL of EtOH and radioactivity was counted in 7 mL of scintillation cocktail (ACS II). All experiments were performed in duplicate. 4.4. Molecular modeling Structure of LBD of human PR and AR were prepared from the Protein Data Bank accession 1A28 and 1E3G, respectively. The structure added for polar hydrogens, and partial atomic charges were assigned using AutoDockTools (ADT).32 Structures of ligand were optimized using MOPAC 2012 (Stewart J. J. P., Stewart Computational Chemistry, Colorado Springs, CO, USA, http:// OpenMOPAC.net (2012)) with PM3 parameters and partial atomic charges of them were assigned using ADT. Molecular docking was performed using AutoDock 4.2 with Genetic Algorithm. Autodock parameter for boron atom Rii = 4.08 and eii = 0.180 were used. Acknowledgments This work was partly supported by JSPS KAKENHI Grant Nos. 23790128 and 25360146 (to F.S.) and No. 22136013 (to H.K.), JSPS Core-to-Core Program, A. Advanced Research Networks, and MEXT Platform for Drug Discovery, Informatics, and Structural Life Science, Japan. References and notes 1. Mangelsdorf, D. J.; Thummel, C.; Beato, M.; Herrlich, P.; Schuetz, G.; Umesono, K.; Blumberg, B.; Kastner, P.; Mark, M. Cell 1995, 83, 835. 2. Psychoyos, A. Vitam. Horm. 1973, 31, 201. 3. Lydon, J. P.; Demayo, F. J.; Funk, C. R.; Mani, S. K.; Hughes, A. R.; Montgomery, C. A.; Shyamala, G.; Conneely, O. M.; O’Malley, B. W. Gene Dev. 1995, 9, 2266. 4. Zhang, Z.; Funk, C.; Glasser, S. R.; Mulholland, J. Endocrinology 1994, 135, 1256. 5. Mani, S. K.; Allen, J. M. C.; Clark, J. H.; Blaustein, J. D.; O’Malley, B. W. Science 1994, 265, 1246. 6. Edgren, R. A.; Sturtevant, F. M. Am. J. Obstet. Gynecol. 1976, 125, 1029. 7. Torgerson, D. J.; Bell-Syer, S. E. JAMA 2001, 285, 2891. 8. Vercellini, P.; De Giorgi, O.; Oldani, S.; Cortesi, I.; Panazza, S.; Crosgnani, P. G. Am. J. Obstet. Gynecol. 1996, 175, 396. 9. Fensome, A.; Bender, R.; Chopra, R.; Cohen, J.; Collins, M. A.; Hudak, V.; Malakian, K.; Lockhead, S.; Olland, A.; Svenson, K.; Terefenko, E. A.; Unwalla, R. J.; Wilhelm, J. M.; Wolfrom, S.; Zhu, Y.; Zhang, Z.; Zhang, P.; Winneker, R. C.; Wrobel, J. J. Med. Chem. 2005, 48, 5092. 10. Teutsch, G.; Philibert, D. History and Perspectives of Anti-Progestins from the Chemist’s Point of View. In Human Reproduction; Edwards, R. G., Ed.; ; Oxford University Press: Oxford, England, 1994; Vol. 9, p 12. Suppl. 1. 11. Kettel, L. M.; Murphy, A. A.; Mortola, J. F.; Liu, J. H.; Ulmann, A.; Yen, S. S. Fertil. Steril. 1991, 56, 402. 12. Murphy, A. A.; Kettel, L. M.; Morales, A. J.; Roberts, V. J.; Yen, S. S. J. Clin. Endocrinol. Metab. 1993, 76, 513.

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