Novel series of potent, nonsteroidal, selective androgen receptor modulators based on 7H-[1,4]oxazino[3,2-g]quinolin-7-ones

Article abstract of DOI:10.1021/jm061329j

Recent interest in orally available androgens has fueled the search for new androgens for use in hormone replacement therapy and as anabolic agents. In pursuit of this, we have discovered a series of novel androgen receptor modulators derived from 7H-[1,4]oxazino[3,2-g]quinolin-7-ones. These compounds were synthesized and evaluated in competitive binding assays and an androgen receptor transcriptional activation assay. A number of compounds from the series demonstrated single-digit nanomolar agonist activity in vitro. In addition, lead compound (R)-16e was orally active in established rodent models that measure androgenic and anabolic properties of these agents. In this assay, (R)-16e demonstrated full efficacy in muscle and only partially stimulated the prostate at 100 mg/kg. These data suggest that these compounds may be utilized as selective androgen receptor modulators or SARMs. This series represents a novel class of compounds for use in androgen replacement therapy.

Full text of DOI:10.1021/jm061329j

2486
J. Med. Chem. 2007, 50, 2486-2496
Novel Series of Potent, Nonsteroidal, Selective Androgen Receptor Modulators Based on
7H-[1,4]Oxazino[3,2-g]quinolin-7-ones
Robert I. Higuchi,* Kristen L. Arienti,† Francisco J. Lo´pez, Neelakhanda S. Mani,† Dale E. Mais, Thomas R. Caferro,
Yun Oliver Long, Todd K. Jones,† James P. Edwards,† Lin Zhi, William T. Schrader,‡ Andre´s Negro-Vilar, and
Keith B. Marschke
DiscoVery Research, Ligand Pharmaceuticals, Inc., 10275 Science Center DriVe, San Diego, California 92121
ReceiVed NoVember 15, 2006
Recent interest in orally available androgens has fueled the search for new androgens for use in hormone
replacement therapy and as anabolic agents. In pursuit of this, we have discovered a series of novel androgen
receptor modulators derived from 7H-[1,4]oxazino[3,2-g]quinolin-7-ones. These compounds were synthesized
and evaluated in competitive binding assays and an androgen receptor transcriptional activation assay. A
number of compounds from the series demonstrated single-digit nanomolar agonist activity in vitro. In
addition, lead compound (R)-16e was orally active in established rodent models that measure androgenic
and anabolic properties of these agents. In this assay, (R)-16e demonstrated full efficacy in muscle and only
partially stimulated the prostate at 100 mg/kg. These data suggest that these compounds may be utilized as
selective androgen receptor modulators or SARMs. This series represents a novel class of compounds for
use in androgen replacement therapy.
Introduction
The androgen receptor (ARa) is a member of the intracellular
receptor superfamily of ligand-dependent transcription factors.1
The native hormones for AR are testosterone (T) and dihy-
drotestosterone (DHT, Figure 1). When bound to AR, these
ligands play important roles in sexual development and function2
and musculo-skeletal growth.3 Androgen therapy is effective
for the treatment of androgen insufficiency. However, the
broader use of steroidal androgens for additional treatments,
such as osteoporosis or frailty, is limited by undesirable AR-
mediated effects, such as prostatic hypertrophy and hirsutism.
A selective androgen receptor modulator (SARM) with full
anabolic activity but reduced impact on the undesirable effects
could have a large role on endocrine therapies to treat muscle
wasting and osteoporosis.4 Early studies on modified androgens
explored alkylation at C-17, as in fluoxymesterone (1).5
However, compounds from this general class are associated with
potential liver toxicity and are met with limited clinical use.2
Recently, the discovery of novel androgens has shifted toward
nonsteroidal templates, and a number of SARMs derived from
classical androgen antagonists flutamide and bicalutamide have
been reported (2).6 Ongoing publication activity in the androgen
field is a testament to the high level of interest for safe, effective
anabolic agents.7 Our interest in novel SARMs was derived from
our earlier studies on pyrano- and pyridono-fused quinoline
Figure 1. Steroidal and nonsteroidal androgens.
agonists (3a and 3b, respectively), which demonstrated potent
levator ani (LA) muscle weight when dosed orally in castrated
AR agonist activity in luciferase-based reporter cell-based
rats. It was hypothesized that replacing the quinoline with the
corresponding benzoxazine could result in compounds less prone
to metabolic oxidation and potentially lead to compounds with
improved in vivo activity. This concept is supported by the fact
that 3b analogues that possess geminal alkyl disubstitution9 at
the R3 position show improved exposure in oral pharmacokinetic
studies, but converted the analogues to AR antagonists.10 In our
studies, we sought to determine if the quinoline nitrogen in 3b
could be substituted with an oxygen and if the replacement of
the CR1 group in 3b with an NR1 present in 5 would also be
tolerated (Figure 2).8a,b This led to the design and preparation
of a series of novel androgens derived from 7H-[1,4]oxazino-
assays.8 However, neither series, including lead compound 3c
(LG121071), exhibited good activity in the maintenance of
* To whom correspondence should be addressed. Phone: (858) 550-
7627. Fax: (858) 550-7249. E-mail: rhiguchi@ligand.com.
† Current address: Johnson & Johnson Pharmaceutical Research and
Development, L. L. C., 3210 Merryfield Row, San Diego, CA 92121.
‡ Current address: National Institute of Environmental Health Sciences,
111 T. W. Alexander Drive, Research Triangle Park, NC 27709.
a Abbreviations: AR, androgen receptor; T, testosterone; DHT, 4,5R-
dihydrotestosterone; SARM, selective androgen receptor modulator; MR,
mineralocorticoid receptor; GR, glucocorticoid receptor; PR, progesterone
receptor; VP, ventral prostate; SV, seminal vesicle; LA, levator ani; LH,
leutinizing hormone.
10.1021/jm061329j CCC: $37.00 © 2007 American Chemical Society
Published on Web 04/17/2007

Nonsteroidal SelectiVe Androgen Receptor Modulators
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10 2487
Scheme 3a
Figure 2. Design elements of AR pharmacophore 5.
Scheme 1a
a Reagents and conditions: (a) R2C(O)CH2Cl, K2CO3, acetone; then
NaBH3CN, TFA; (b) HOAc/HCl; (c) R1CHO, NaBH3CN, HOAc, rt.
Scheme 4a
a Reagents and conditions: (a) R2C(O)CH2X, K2CO3, acetone; then
NaBH3CN, TFA; (b) R1CHO, NaBH3CN, HOAc, rt; (c) 10% Pd-C, H2;
(d) ethyl 4,4,4-trifluoroacetoacetate, benzene, reflux; (e) PPA or concd
H2SO4, 100 °C.
a Reagents and conditions: (a) borane dimethyl sulfide, THF, reflux;
(b) R1CHO, NaBH3CN, HOAc, rt; (c) 10% Pd-C, H2, EtOAc, EtOH, rt,
or Zn dust, CaCl2, EtOH/H2O (95:5), reflux; (d) ethyl 4,4,4-trifluoroac-
etoacetate, benzene, reflux; (e) PPA or concd H2SO4, 100 °C.
subjected to reductive amination to afford 16. Alternatively, 16
could be prepared by the benzoxazine protocol described above
to afford 17 (Scheme 4). Reductive amination, nitro reduction,
followed by the Knorr reaction, as described previously, affords
16. Chiral HPLC separation of 10 and 16 was achieved utilizing
a Chiralpak AD column.
Scheme 2a
To evaluate our compounds in rodent models, an enantiospe-
cific synthesis was desired to facilitate evaluation of compounds
in longer-term models. Enantiospecific syntheses of simple 2H-
1,4-benzoxazine systems have been reported previously;15
however, none of the reported methods derive diversity from
the amino alcohol chiral pool. The synthesis of the desired
compounds is described in Scheme 5. Nucleophilic substitution
of 3,4-dinitrofluorobenzene with commercially available amino
alcohols afforded 20. Acetal formation followed by Lewis acid-
mediated reductive ring opening provided 22. With the tertiary
amine, closure to the benzoxazine proceeded in good yields (23).
This scheme provides an efficient enantiospecific synthesis of
both (trifluoroethyl)amino alcohols and the corresponding
benzoxazines. In addition, this allows for the assignment of
absolute configuration of (R) for the 1-(2,2,2-trifluoroethyl)
analogues, which is established when the (R)-enantiomer of the
amino alcohol is used as the starting material. This methodology
was also an effective method to generate newer analogues in
asymmetrically pure form.
a Reagents and conditions: (a) R1CHO, NaBH3CN, HOAc, rt.
[3,2-g]quinolin-7-ones (5). Along with the 6-N,N-bis(2,2,2-
trifluoroethyl)amino-4-trifluoromethylquinolin-2(1H)-one 4
(LGD2226) series,11 this manuscript describes our efforts in the
discovery of new nonsteroidal AR modulators.
Chemistry
A flexible synthetic strategy that allowed for facile substitu-
tions at the 1- and 3-positions of 5 is shown in Scheme 1.
Compounds 612 and 713 were prepared from methods described
in the literature, followed by alkylation at nitrogen by treatment
with an aldehyde and sodium cyanoborohydride. Reduction of
the nitro group to the corresponding aniline (9) was followed
by treatment with 4,4,4-trifluoroacetoacetate in refluxing ben-
zene, followed by treatment of the crude acetanilide with strong
acid, either polyphosphoric acid (PPA) or concentrated H2SO4
(Knorr reaction),14 to afford the desired 4-substituted-7H-[1,4]-
oxazino[3,2-g]quinolin-7-one (10). Acid-sensitive groups that
do not survive the harsh Knorr reaction conditions, such as a
cyclopropylmethyl group, can be prepared by reductive ami-
nation of compound 11 (Scheme 2).
Results and Discussion
The compounds were evaluated in a transcriptional activation
assay with hAR in a mammalian cell background (CV-1), as
previously described, and was the primary in vitro assay utilized
to measure the AR activity.9 Competitive receptor binding assays
for AR were performed using MDA-MB-453 cells and was used
to confirm the activity observed in the transactivation assay.
MDA-MB-453 cells are human breast carcinoma cells that
2-Substituted analogues were prepared by treatment of an
aminophenol and an R-haloketone followed by NaBH3CN
reduction to afford 14 (Scheme 3). Hydrolysis to the pyridone
was accomplished by treatment with strong acid, then 15 was

2488 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10
Higuchi et al.
Scheme 5a
(10a and 10f). The 3-ethyl substitution is less tolerated, where
compounds 10i, 10j, and 10k show weaker activity relative to
that of their corresponding parent compounds 10a, 10b, and
10f. To address the chirality issue, (+)-10h and (-)-10h were
prepared by chiral HPLC separation of 10h and characterized
in the assays. The test result demonstrates that a majority of
the AR agonist activity resides in one enantiomer, (-)-10h.
Assay results of the 2-substituted analogues are summarized
in Table 2. The racemic 2-methyl analogue 15a shows weaker
AR agonist activity than that of the 1-ethyl-2-methyl analogue
16a, which indicates the importance of the substitution at the
1-position, although 15a is a significant improvement over
parent compound 11a. Introduction of a methyl or ethyl group
at the 2-position is generally tolerated, but their relative tolerance
depends on the substitution at the 1-position. When R1 is ethyl
or cyclopropylmethyl, the 2-ethyl and 2-methyl analogues have
similar activity. When R1 is trifluoroethyl, 2-methyl compound
16e is more active than 2-ethyl compound 16f in the transcrip-
tional activation assay. Two pairs of enantiomers (16e,f) were
prepared individually and evaluated to study the effect of the
chirality on the modulating activity. Both enantiomers of 16e,f
are AR agonists, though the (S)-enantiomers of 16e and 16f
tend toward lower agonist efficacy and potency than the
corresponding R-enantiomers. Two enantiomerically pure ana-
logues with a larger R2 group [(R)-16g and (R)-16h] behave
more as partial agonists. Ring-fused analogues 27 and 28
examined whether fusing the R1- and R2-substituents in a ring
could enhance the activity. These compounds likewise were AR
agonists, but this did not lead to an improvement in activity
over the corresponding acyclic substituents.
a Reagents and conditions: (a) NaHCO3, EtOH, reflux; (b) trifluoroac-
etaldehyde ethyl hemiacetal, p-TsOH, reflux; (c) TiCl4 or BF3, Et3SiH; (d)
NaH, THF, reflux; (e) ethyl 4,4,4-trifluoroacetoacetate, benzene, reflux; (f)
PPA or concd H2SO4, 100 °C.
Selected compounds in the series were tested in steroid
hormone binding selectivity assays (Table 3). None of the
compounds showed appreciable activity toward the mineralo-
corticoid (MR) nor glucocorticoid (GR) receptors. Some of the
compounds show low micromolar affinity for the progesterone
receptor (PR), but this represents significantly weaker activity
compared to the AR binding affinity.
express high levels of AR and are responsive to androgens.16
The unsubstituted analogue 11a was a weakly potent AR
antagonist and did not possess any agonist activity (Table 1).
The introduction of an alkyl group at the 1-position converted
the antagonist into an agonist, and the size of the alkyl group is
critical to the AR modulating activity. For the small alkyl
analogues, single-digit nanomolar potency for AR is observed
for a number of the R1-substituted analogues (10b-f, 12a) in
the AR transcriptional activation assay. The optimal size of R1
for a full agonist is about 2-3 carbons (compounds 10b, 10c,
and 10f). The analogues with slightly less optimal R1 size tend
to have partial agonist activity, such as analogues with methyl
(10a) and t-butyl (10e). Increasing the size to benzyl (12b)
converts the compounds back to an antagonist, with no agonist
activity detected. This SAR trend for the benzoxazine series
(5) is similar to that observed for the tetrahydroquinoline (3b)
series, where the presence of a small alkyl group is likewise
beneficial for AR agonist activity. Furthermore, the utilization
of the NR1 group in 5 eliminates the chiral center present in
the R1 position in the racemic 3b series. These initial analogues
demonstrated that both the replacement of the quinoline nitrogen
in 3b with oxygen and the utilization of an NR1 group at the
1-position are well tolerated and that 5 was a viable AR
modulator scaffold suitable for further exploration.
Although the in vitro potencies of the 2-substituted analogues
were similar to the unsubstituted compounds, lead compound
(R)-16e demonstrated improved oral exposure over 10b and 10f.
To demonstrate in vivo proof-of-concept for this series of AR
modulators, (R)-16e was evaluated in a 4-week castrated mature
rat assay.17 The male sexual accessory organs, such as the ventral
prostate (VP) and the seminal vesicles (SV), play an important
role in reproductive function. These glands are stimulated to
grow and are maintained in size and function by the presence
of endogenous androgens. This model is used to determine the
androgen-dependent growth of the sex accessory organs in
mature castrated rats. In addition to the VP and SV, the LA
muscle demonstrates androgen-dependent growth,17 hence, the
LA muscle is a useful endpoint to evaluate anabolic effects. A
SARM should have full efficacy on LA muscle and a reduced
impact on VP to maximize the anabolic effects, while minimiz-
ing the risk of prostate overstimulation.
Although many of the monosubstituted compounds at R1 of
5 demonstrated good AR in vitro activity, they were character-
ized by poor exposure in 1-day oral pharmacokinetic studies.
To improve oral exposure while maintaining the functional
activity, we investigated analogues with a small alkyl group at
the 2- or 3-position of the molecule while keeping the R1 as an
optimal small alkyl group. Unfortunately, this resulted in the
introduction of a chiral center either at the R2 or the R3 position.
The racemic 3-methyl compounds (10g and 10h) show com-
parable AR activity to the corresponding unsubstituted analogues
In this model, T is reported to have equivalent potency and
efficacy on both the VP and the LA muscle when dosed
subcutaneously, and is hence considered not muscle-selective.11
Because T is rapidly metabolized when dosed orally and,
therefore, ineffective, 1 was chosen as the orally active positive
control in this experiment. As can be seen in Figure 3, 100 mg/
kg of (R)-16e maintains the LA muscle weight at the intact
level (Table 4). At this dose, the compound shows less activity
(∼25-50%) on the VP and SV weights. The tissue selectivity
profile for (R)-16e on VP and LA weight is similar to that

Nonsteroidal SelectiVe Androgen Receptor Modulators
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10 2489
Table 1. Activity in the AR Transcriptional Activation and AR Binding Assaysa
hAR agonist
hAR antagonist
Eff (%) IC50 (nM)
AR bind.
cmpd
DHT
1
3c
11a
10a
10b
10c
10d
10e
R1
R3
eff (%)
100
124 ( 9
100 ( 7
-
EC50 (nM)
Ki (nM)
5.7 ( 0.1
0.3 ( 0.1
4.1 ( 0.9
-
-
-
-
-
-
-
0.3 ( 0.0
5.7 ( 0.2
11 ( 2
H
H
H
H
H
H
H
H
H
72 ( 3
-
-
-
27 ( 27
-
-
-
296 ( 100
-
-
>1000b
Me
Et
Pr
56 ( 10
92 ( 8
83 ( 8
70 ( 11b
62 ( 3
88 ( 5
68 ( 5
-
50 ( 8
104 ( 10
28 ( 4
53 ( 2
72 ( 11
35 ( 12
82 ( 3
18 ( 3
15 ( 3b
1.2 ( 0.4
9.6 ( 7.1b
17 ( 14b
48 ( 42b
4.0 ( 1.0
1.6 ( 0.2
206 ( 17b
33 ( 10
15 ( 5b
6.4 ( 1.7
2.4 ( 0.3
3.2 ( 0.6
7.8 ( 2.6
3.5 ( 1.3
1.4 ( 0.3
-
-
i-Bu
t-Bu
CH2CF3
C3H6CH2
Bn
ndc
-
-
-
10f
12a
12b
10g
10h
10i
H
90 ( 2
224 ( 44
Me
Me
Me
Et
Et
Et
Me
Me
47 ( 5
21 ( 11
ndc
CH2CF3
Me
8.9 ( 2.7
52 ( 8
-
-
32 ( 11
-
-
29 ( 8
-
67 ( 24
-
58 ( 17
34 ( 7
10j
Et
31 ( 3
10k
(+)-10h
(-)-10h
CH2CF3
CH2CF3
CH2CF3
15 ( 6
-
30 ( 9
44 ( 5
ndc
-
75 ( 22
25 ( 4
7.8 ( 0.6
a AR transcriptional activation and AR binding experimental results with at least three separate experiments in triplicate with SEM. b Mean value from
two experiments. A hyphen is indicative of efficacy <20% or a potency >10 000 nM. c nd means the EC50 could not be calculated.
Table 2. AR Agonist and Binding Data for 2-Substituted Analoguesa
Table 3. Steroid Hormone Binding Selectivitya
cmpd
AR Kib (nM)
PR Ki (nM)
GR Ki (nM)
10b
10f
10h
12a
16d
16e
16f
28
1.2 ( 0.4
4.0 ( 1.0
15c ( 5
1.6 ( 0.2
23c ( 19
7.8 ( 1.2
9.4c ( 2.5
16c ( 11
5200 ( 2700
5300 ( 2700
7000 ( 3000
2000 ( 930
5400 ( 2400
2800 ( 600
2800 ( 240
-
8100 ( 1800
9200 ( 840
-
8800 ( 1200
-
8500 ( 1500
6500 ( 3500
-
hAR agonist
AR bind.
cmpd
15a
16a
16b
16c
16d
16e
16f
(S)-16e
(R)-16e
(S)-16f
(R)-16f
(R)-16g
(R)-16h
(R)-27
28
R1
R2
eff (%)
EC50 (nM)
Ki (nM)
H
Et
Et
Me
Me
Et
Me
Et
Me
Et
Me
Me
Et
80 ( 3b
61 ( 4
80 ( 20
65 ( 5
71 ( 8
96 ( 12
69 ( 4
58 ( 4
82 ( 5
49 ( 3
85 ( 9
46 ( 23
65 ( 15
46 ( 13
75 ( 5
133 ( 9
10 ( 7
113 ( 50b
4.2 ( 0.3b
5.6 ( 1.6b
4.0 ( 0.9b
23 ( 19b
7.8 ( 1.2
9.4 ( 2.5b
5.7 ( 1.5
7.1 ( 1.9
19 ( 4b
a Experimental results with at least three separate experiments in triplicate
with SEM. Binding experiments were carried out with baculovirus expressed
receptors, except where otherwise indicated. b Whole-cell binding in MDA
cells. c Mean value from two experiments. A hyphen is indicative of Ki >
10 000 nM. All compounds from Table 3 were evaluated in a MR binding
assay and were found to have a Ki > 10 000 nM in all instances.
3.9 ( 2.0
1.9 ( 0.3
2.3 ( 0.4
2.7 ( 0.5
6.0 ( 1.5
3.8 ( 0.4
1.1 ( 0.2
30 ( 22
2.7 ( 1.1
5.9 ( 0.4
27 ( 13
26 ( 14
14 ( 4
C3H6CH2
C3H6CH2
CH2CF3
CH2CF3
CH2CF3
CH2CF3
CH2CF3
CH2CF3
CH2CF3
CH2CF3
ity in vitro across a number of analogues, while having minimal
or no impact on GR, MR, or PR. Compound (R)-16e demon-
strates in vivo activity in an established rodent model of
androgen action. At 100 mg/kg, (R)-16e maintains LA muscle
weight at the intact levels after oral administration for 4 weeks,
while showing reduced activity in VP weight, demonstrating a
muscle selectivity profile comparable to 1. Furthermore, an
enantiospecific synthesis of the benzoxazine core was developed
and resulted in the establishment of the absolute configuration
of the chiral center of the 2-position (R), as well as facilitating
the evaluation of (R)-16e in vivo. This series of compounds
offer good opportunities to identify new androgen modulators
as anabolic agents and further studies directed toward improving
the in vivo potency of these analogues will be reported in due
course.
Et
i-Pr
i-Bu
2.8 ( 0.3b
51 ( 36b
109 ( 52b
27
16 ( 11b
a AR transcriptional activation and AR binding experimental results with
at least three separate experiments in triplicate with SEM. b Mean value
from two experiments. If no SEM is noted, value is from a single
determination.
observed for 1. This profile could be beneficial in androgen
therapy, where over-stimulation of the sexual accessory tissues
should be avoided to limit the risk of prostate hypertrophy or
hyperplasia. (R)-16e also reduces leutinizing hormone (LH)
levels, another marker of androgen activity in vivo.8a
Experimental Section
Conclusion
Proton nuclear magnetic resonance (1H NMR) and carbon-13
nuclear magnetic resonance (13C NMR) were recorded at 400 and
100 MHz, respectively, on a Bruker AC 400 or at 500 and 125
MHz on a Varian Unity Inova 500. Chemical shifts are given in
parts per million (ppm) downfield from internal reference tetra-
methylsilane in δ units. Elemental analyses were performed at
We have described a receptor-selective and potent series of
AR modulators based on 7H-[1,4]oxazino[3,2-g]quinolin-7-ones.
A number of compounds, particularly those substituted at the
1- and 2-positions demonstrate potent activity in vitro. The
1-(2,2,2-trifluoroethyl) substituent exhibits very good AR activ-

2490 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10
Higuchi et al.
prepared from 7a (530 mg, 2.9 mmol) and propionaldehyde (1.61
1
g, 28 mmol). Rf 0.57 (2:1 EtOAc/hexanes); H NMR (400 MHz,
CDCl3) δ 7.80 (dd, 1H, J ) 9.1, 2.6), 7.66 (d, 1H, J ) 2.6), 6.56
(d, 1H, J ) 9.0), 4.22 (t, 2H, J ) 4.5), 3.49 (t, 2H, J ) 4.5), 3.33
(t, 2H, J ) 7.5), 1.67 (sext, 2H, J ) 7.4), 0.98 (t, 3H, J ) 7.4).
3,4-Dihydro-4-isobutyl-7-nitro-2H-1,4-benzoxazine (8d, R1 )
isobutyl, R3 ) H). Compound 8d (713 mg, 99%) was prepared
from 7a (550 mg, 3.0 mmol) and isobutyraldehyde (1.65 g, 22.8
mmol). Rf 0.75 (3:2 EtOAc/hexanes); 1H NMR (400 MHz, CDCl3)
δ 7.78 (dd, 1H, J ) 9.0, 2.6), 7.66 (d, 1H, J ) 2.6), 6.55 (d, 1H,
J ) 9.2), 4.21 (t, 2H, J ) 4.5), 3.52 (t, 2H, J ) 4.6), 3.16 (d, 2H,
J ) 7.4), 3.12 (hept, 1H, J ) 6.9), 0.97 (d, 6H, J ) 6.7).
4-(2,2-Dimethylpropyl)-3,4-dihydro-7-nitro-2H-1,4-benzox-
azine (8e, R1 ) 2,2-dimethylpropyl, R3 ) H). Compound 8e (38
mg, 27%) was prepared from 7a (100 mg, 0.55 mmol) and
trimethylacetaldehyde in TFA. 1H NMR (400 MHz, CDCl3) δ 7.75
(dd, 1H, J ) 9.2, 2.7), 7.65 (d, 1H, J ) 2.7), 6.68 (d, 1H, J ) 9.2),
4.23 (t, 2H, J ) 4.4), 3.54 (t, 2H, J ) 4.5), 3.19 (s, 2H), 1.02 (s,
9H).
(()-3,4-Dihydro-2,4-dimethyl-7-nitro-2H-1,4-benzoxazine (8g,
R1 ) Me, R3 ) Me). Compound 8g (160 mg, 99%) was prepared
from 7b (150 mg, 0.77 mmol) and paraformaldehyde (233 mg, 7.8
mmol). Rf 0.77 (3:2 EtOAc/hexanes); 1H NMR (400 MHz, CDCl3)
δ 7.81 (dd, 1H, J ) 9.1, 2.5), 7.66 (d, 1H, J ) 2.5), 6.55 (d, 1H,
J ) 8.9), 4.26-4.23 (m, 1H), 3.32 (dd, 1H, J ) 12.1, 2.7), 3.22
(dd, 1H, J ) 12.0, 8.2), 3.03 (s, 3H), 1.39 (d, 3H, J ) 6.5).
(()-2-Ethyl-3,4-dihydro-4-methyl-7-nitro-2H-1,4-benzoxa-
zine (8i, R1 ) Me, R3 ) Et). Compound 8i (127 mg, 99%) was
prepared from 7c (120 mg, 0.57 mmol) and paraformaldehyde (174
Figure 3. (R)-16e and 1 in a 4-week castrated mature rat model. The
dashed lines (s) represent intact levels. P < 0.05 vs vehicle (one-way
ANOVA, followed by Dunnett’s test).
Table 4. Efficacy of (R)-16e and 1 Compared to Intact Control for VP
and LA Weight
treatment (mg/kg)
LA efficacya
VP efficacya
(R)-16e (100)
1 (100)
intact
85 ( 11
129 ( 5
100 ( 9
27 ( 3
79 ( 8
100 ( 6
1
mg, 5.8 mmol). Rf 0.89 (11.5:1 CH2Cl2/MeOH); H NMR (400
a Efficacy compared to intact control.
MHz, CDCl3) δ 7.81 (dd, 1H, J ) 9.0, 2.5), 7.67 (d, 1H, J ) 2.5),
6.54 (d, 1H, J ) 9.0), 4.01 (m, 1H), 3.34 (dd, 1H, J ) 12.0, 2.7),
3.23 (dd, 1H, J ) 12.0, 8.1), 3.03 (s, 3H), 1.79-1.72 (m, 1H),
1.67-1.60 (m, 1H), 1.07 (t, 3H, J ) 7.5).
Quantitative Technologies, Inc., Whitehouse, NJ. Column chro-
matography was performed on silica gel using Merck 230-400
mesh silica gel. Analytical thin layer chromatography (TLC) was
performed using Merck 60-F-254 0.25 mm precoated silica gel
plates. Low- and high-resolution electrospray ionization (ESI) mass
spectrometry was performed on a Micromass LCT Mass Spec-
trometer.
Analytical HPLC for selected compounds were performed on
two systems. System A, Kromasil 100 (C18, 5 µm, 150 × 4.6 mm,
1.0 mL/min); system B, Beckman Si (5 µm, 250 × 4.6 mm, 1.0
mL/min). Using two analytical methods, the purity of the com-
pounds was determined to be >95% using UV detection at 254
nM.
(()-2,4-Diethyl-3,4-dihydro-7-nitro-2H-1,4-benzoxazine (8j,
R1 ) Et, R3 ) Et). Compound 8j (72 mg, 42%) was prepared
1
from 7c (150 mg, 0.70 mmol) and acetaldehyde. H NMR (400
MHz, CDCl3) δ 7.80 (dd, 1H, J ) 9.1, 2.6), 7.68 (d, 1H, J ) 2.5),
6.57 (d, 1H, J ) 9.0), 3.90-4.00 (m, 1H), 3.48-3.60 (m, 1H),
3.25-3.40 (m, 2H), 3.25 (dd, 1H, J ) 12.1, 8.0), 1.60-1.80 (m,
2H), 1.21 (t, 3H, J ) 7.1), 1.08 (t, 3H, J ) 7.4).
3,4-Dihydro-4-(p-methoxybenzyl)-7-nitro-2H-1,4-benzoxa-
zine (8l, R1 ) 4-anisyl, R3 ) H). Compound 8l (361 mg, 70%)
was prepared from 7a (305 mg, 1.7 mmol) and p-anisaldehyde (2.3
1
g, 17 mmol). Rf 0.79 (3:2 EtOAc/hexanes); H NMR (400 MHz,
CDCl3) δ 7.76 (dd, 1H, J ) 9.0, 2.6), 7.70 (d, 1H, J ) 2.5), 7.14
(d, 2H, J ) 8.6), 6.88 (d, 2H, J ) 8.6), 6.63 (d, 1H, J ) 9.1), 4.54
(s, 2H), 4.26 (t, 2H, J ) 4.5), 3.80 (s, 3H), 3.51 (t, 2H, J ) 4.6).
General Procedure 2: Reductive Amination To Form a 2,2,2-
(Trifluoroethyl)amine. To a solution of a 7 (1.0 equiv) in
trifluoroacetic acid (0.5 mL/mmol) was added 2,2,2-trifluoroac-
etaldehyde monohydrate (10 equiv), and the mixture was stirred at
rt for 2 h. To this mixture was added portionwise sodium
cyanoborohydride (4.8 equiv) and the mixture was stirred at room
temperature overnight. [Caution: Add the sodium cyanoborohydride
slowly and provide a gentle cone of nitrogen to minimize the
introduction of air.] The resulting mixture was poured over ice,
neutralized with 6 M NaOH solution to pH 7.0, extracted with CH2-
Cl2 (3 × 30 mL/mmol), and washed with pH 7 phosphate buffer
(50 mL/mmol) and brine (50 mL/mmol). The organic solution was
dried (MgSO4) and concentrated under reduced pressure to afford
the desired product as a yellow solid.
3,4-Dihydro-7-nitro-4-(2,2,2-trifluoroethyl)-2H-1,4-benzoxa-
zine (8f, R1 ) CH2CF3, R3 ) H). Compound 8f (500 mg, 88%),
a yellow solid, was prepared from 7a (388 mg, 2.1 mmol). Rf 0.59
(3:2 EtOAc/hexanes); 1H NMR (400 MHz, CDCl3) δ 7.81 (dd, 1H,
J ) 8.8, 2.6), 7.72 (d, 1H, J ) 2.6), 6.72 (d, 1H, J ) 9.1), 4.27 (t,
2H, J ) 4.5), 3.94 (q, 2H, J ) 8.6), 3.61 (t, 2H, J ) 4.5).
(()-3,4-Dihydro-2-methyl-7-nitro-4-(2,2,2-trifluoroethyl)-2H-
1,4-benzoxazine (8h, R1 ) CH2CF3, R3 ) Me). Compound 8h
(550 mg, 96%), a yellow solid, was prepared from 7b (400 mg,
General Procedure 1: Reductive Amination with Sodium
Cyanoborohydride in Acetic Acid. To a solution of 7 (1.0 equiv)
in acetic acid (7.8 mL/mmol) was added an aldehyde (10 equiv),
and the mixture was stirred at rt for 1 h. To this mixture was added
portionwise sodium cyanoborohydride (4.8 equiv) and stirred at
room temperature overnight. The resulting mixture was poured over
ice, neutralized with 6 M NaOH to pH 7.0, extracted with CH2Cl2
(3 × 30 mL/mmol), and washed with pH 7 phosphate buffer (50
mL/mmol) and brine (50 mL/mmol). The organic solution was dried
(MgSO4) and concentrated under reduced pressure to afford the
desired N-alkylated product as a yellow solid.
3,4-Dihydro-4-methyl-7-nitro-2H-1,4-benzoxazine (8a, R1 )
Me, R3 ) H). Compound 8a (1.21 g, 98%) was prepared from 7a
(1.15 g, 6.38 mmol) and paraformaldehyde (1.92 g, 64.1 mmol).
1
Rf 0.83 (11.5:1 CH2Cl2/MeOH); H NMR (400 MHz, CDCl3) δ
7.82 (dd, 1H, J ) 9.0, 2.6), 7.65 (d, 1H, J ) 3.4), 6.56 (d, 1H, J
) 8.9), 4.27 (t, 2H, J ) 4.6), 3.46 (t, 2H, J ) 4.5), 3.05 (s, 3H).
4-Ethyl-3,4-dihydro-7-nitro-2H-1,4-benzoxazine (8b, R1 ) Et,
R3 ) H). Compound 8b (984 mg, 74%) was prepared from 7a
(1.15 g, 6.39 mmol) and acetaldehyde (3.59 mL, 64.2 mmol). Rf
0.85 (11.5:1 CH2Cl2/MeOH); 1H NMR (400 MHz, CDCl3) δ 7.81
(dd, 1H, J ) 9.6, 2.6), 7.66 (d, 1H, J ) 2.7), 6.29 (d, 1H, J ) 9.2),
4.23 (t, 2H, J ) 4.7), 3.47 (t, 2H, J ) 4.7), 3.45 (q, 2H, J ) 7.2),
1.22 (t, 3H, J ) 7.0).
3,4-Dihydro-7-nitro-4-propyl-2H-1,4-benzoxazine (8c, R1 )
Pr, R3 ) H). Compound 8c (450 mg, 69%), an orange oil, was

Nonsteroidal SelectiVe Androgen Receptor Modulators
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10 2491
1
2.0 mmol). Rf 0.85 (3:2 EtOAc/hexanes); H NMR (400 MHz,
(()-7-Amino-2-ethyl-3,4-dihydro-4-methyl-2H-1,4-benzox-
azine (9i, R1 ) Me, R3 ) Et). Compound 9i (80 mg, 71%) was
prepared from 8i (130 mg, 0.6 mmol). Rf 0.5 (19:1 CH2Cl2/MeOH);
1H NMR (400 MHz, CDCl3) δ 6.53 (dd, 1H, J ) 9.1, 2.7), 6.25-
6.20 (m, 2H), 4.11 (m, 1H), 3.10 (dd, 1H, J ) 11.4, 2.1), 2.84 (dd,
1H, J ) 11.3, 8.1), 2.78 (s, 3H), 1.75-1.70 (band, 1H), 1.64-
1.58 (m, 1H), 1.03 (t, 2H, J ) 7.5).
CDCl3) δ 7.81 (dd, 1H, J ) 9.2, 2.6), 7.72 (d, 1H, J ) 2.6), 6.72
(d, 1H, J ) 9.1), 4.23 (m, 1H), 4.23-3.82 (m, 2H), 3.47 (dd, 1H,
J ) 12.1, 2.6), 3.37 (dd, 1H, J ) 12.2, 8.2), 1.41 (d, 3H, J ) 6.1).
(()-2-Ethyl-3,4-dihydro-7-nitro-4-(2,2,2-trifluoroethyl)-2H-
1,4-benzoxazine (8k, R1 ) CH2CF3, R3 ) Et). Compound 8k
(346 mg, 99%) was prepared from 7c (250 mg, 1.2 mmol). Rf 0.75
(3:2 EtOAc/hexanes); 1H NMR (400 MHz, CDCl3) δ 7.80 (dd, 1H,
J ) 8.9, 2.6), 7.73 (d, 1H, J ) 2.5), 6.70 (d, 1H, J ) 9.0), 4.03-
3.81 (m, 3H), 3.48 (dd, 1H, J ) 12.1, 2.6), 3.39 (dd, 1H, J ) 12.1,
8.0), 1.80-1.62 (m, 2H), 1.08 (t, 3H, J ) 7.4).
General Procedure 3: Pd-C Hydrogenation of a Nitro
Compound to an Aniline. To a solution of a 4-alkyl-3,4-dihydro-
7-nitro-2H-1,4-benzoxazine in 1:1 EtOAc/EtOH (13 mL/mmol) was
added 10% Pd-C (6% by wt). The flask was flushed, evacuated
with N2 (3×), and then stirred under an atmosphere of H2 overnight.
The reaction mixture was filtered through Celite, washed with
EtOAc (2 × 20 mL/mmol) and concentrated under reduced pressure
to give the desired product as a light purple/tan solid, which was
purified on silica gel (CH2Cl2/MeOH, 20:1) unless otherwise
indicated.
(()-7-Amino-2,4-diethyl-3,4-dihydro-2H-1,4-benzoxazine (9j,
R1 ) Me, R3 ) Et). Compound 9j (43 mg, 70%) was prepared
1
from 8j (70 mg, 0.3 mmol). H NMR (400 MHz, CDCl3) δ 6.54
(d, 1H, J ) 8.1), 6.20-6.30 (m, 2H), 3.98-4.08 (m, 1H), 3.25-
3.35 (m, 1H), 3.10-3.20 (m, 1H), 2.92 (dd, 1H, J ) 11.4, 8.1),
1.70-1.80 (m, 1H), 1.55-1.65 (m, 1H), 1.11 (t, 3H, J ) 7.2), 1.03
(t, 3H, J ) 7.5).
(()-7-Amino-2-ethyl-3,4-dihydro-4-(2,2,2-trifluoroethyl)-2H-
1,4-benzoxazine (9k, R1 ) CH2CF3, R3 ) Et). Compound 9k
(151 mg, 99%) was prepared from 8k (170 mg, 0.6 mmol). Rf 0.62
(3:2 EtOAc/hexanes); 1H NMR (400 MHz, CDCl3) δ 6.56 (d, 1H,
J ) 8.0), 6.25-6.20 (m, 2H), 3.93 (m, 1H), 3.70-3.64 (m, 3H),
3.43 (br s, 1H), 3.31 (m, 1H), 3.12 (dd, 1H, J ) 11.9, 8.1), 1.74-
1.59 (m, 2H), 1.04 (t, 3H, J ) 7.5).
General Procedure 4: Zinc Reduction of a Nitrobenzene
Derivative to an Aniline. A mixture of the nitrobenzene derivative
(1.0 equiv) in ethanol/water (95:5), zinc dust (4.3 equiv), and
calcium chloride dihydrate (2.2 equiv) was heated to reflux for
approximately 4-5 h. The reaction mixture was filtered hot through
a pad of celite and washed with hot EtOAc (100 mL). The solvent
was removed under reduced pressure and partitioned with water
(150 mL) and EtOAc (150 mL). The aqueous layer was then
adjusted to a pH of 3-4 with 20% HCl, extracted with EtOAc (3
× 100 mL), washed with brine (100 mL), dried (MgSO4), and
concentrated under reduced pressure. Purification by flash chro-
matography (silica gel, 20:1, CH2Cl2/MeOH) afforded the desired
aniline.
7-Amino-3,4-dihydro-4-methyl-2H-1,4-benzoxazine (9a, R1 )
Me, R3 ) H). Compound 9a (167 mg, 75%) was prepared from
8a (262 mg, 1.35 mmol). Rf 0.36 (11.5:1 CH2Cl2/MeOH); 1H NMR
(400 MHz, CDCl3) δ 6.55 (d, 1H, J ) 8.2), 6.25 (d, 1H, J ) 2.6),
6.22 (dd, 1H, J ) 7.0, 2.7), 4.28 (t, 2H, J ) 4.4), 3.32 (br s, 2H),
3.13 (t, 2H, J ) 4.5), 2.79 (s, 3H).
7-Amino-4-ethyl-3,4-dihydro-2H-1,4-benzoxazine (9b, R1 )
Et, R3 ) H). Compound 9b (173 mg, 77%) was prepared from 8b
1
(264 mg, 1.3 mmol). Rf 0.52 (11.5:1 CH2Cl2/MeOH); H NMR
(400 MHz, CDCl3) δ 6.56 (d, 1H, J ) 8.1), 6.26-6.22 (m, 2H),
4.23 (t, 2H, J ) 4.4), 3.29 (br s, 2H), 3.24 (q, 2H, J ) 7.1), 3.19
(t, 2H, J ) 4.4), 1.11 (t, 3H, J ) 7.0).
7-Amino-3,4-dihydro-4-propyl-2H-1,4-benzoxazine (9c, R1 )
7-Amino-3,4-dihydro-4-(p-methoxybenzyl)-2H-1,4-benzox-
azine (9l, R3 ) H, R1 ) 4-anisyl). Compound 9l (900 mg, 99%)
was prepared from 8l (1.0 g, 3.3 mmol). Rf 0.60 (24:1 CH2Cl2/
Pr, R3 ) H). Compound 9c (36 mg, 84%) was prepared from 8c
1
(50 mg, 0.2 mmol). Rf 0.43 (2:1 EtOAc/hexanes); H NMR (400
MHz, CDCl3) δ 6.53 (d, 1H, J ) 8.9), 6.25-6.20 (m, 2H), 4.21 (t,
2H, J ) 4.4), 3.28 (br s, 2H), 3.21 (t, 2H, J ) 4.4), 3.08 (t, 2H, J
) 7.5), 1.60 (sext, 2H, J ) 7.4), 0.94 (t, 3H, J ) 7.4).
1
MeOH); H NMR (400 MHz, CDCl3) δ 7.22 (d, 2H, J ) 8.6),
6.86 (d, 2H, J ) 8.6), 6.60 (d, 1H, J ) 8.4), 6.34 (d, 1H, J ) 2.5),
6.30 (dd, 1H, J ) 8.5, 2.4), 4.25 (s, 2H), 4.21 (t, 2H, J ) 4.5),
3.80 (s, 3H), 3.17 (t, 2H, J ) 4.3).
7-Amino-3,4-dihydro-4-isobutyl-2H-1,4-benzoxazine (9d, R1
) Isobutyl, R3 ) H). Compound 9d (621 mg, 99%) was prepared
Enantiospecific Synthesis of Amino Benzoxazine Analogues.
General Procedure 5: Nucleophilic Aromatic Substitution of
3,4-Difluoronitrobenzene with an Amino Alcohol. A mixture of
3,4-difluoronitrobenzene (1.2 equiv) and the amino alcohol (1 equiv)
was dissolved in absolute ethanol (3.3 M) or DMF. To this solution
was added sodium bicarbonate (1 equiv). The suspension was heated
at reflux (EtOH) or the specified temperature for 12 h until TLC
indicated complete conversion of the amino alcohol. After cooling
to room temperature, the reaction mixture was filtered with the aid
of additional ethanol and the filtrate was concentrated under reduced
pressure, which was then purified as indicated.
1
from 8d (712 mg, 3.0 mmol). Rf 0.43 (3:2 EtOAc/hexanes); H
NMR (400 MHz, CDCl3) δ 6.49 (d, 1H, J ) 9.1), 6.23 (m, 2H),
4.20 (t, 2H, J ) 4.4), 3.28 (br s, 2H), 3.23 (t, 2H, J ) 4.4), 2.85
(d, 2H, J ) 7.2), 2.04-1.92 (m, 1H), 0.94 (d, 6H, J ) 6.5).
7-Amino-4-(2,2-dimethylpropyl)-3,4-dihydro-2H-1,4-benzox-
azine (9e, R1 ) 2,2-Dimethylpropyl, R3 ) H). Compound 9e (53
1
mg (100%) was prepared from 8e (60 mg, 0.24 mmol). H NMR
(400 MHz, CDCl3) δ 6.57 (d, 1H, J ) 9.2), 6.18-6.25 (m, 2H),
4.17 (t, 2H, J ) 4.4), 3.27 (t, 2H, J ) 4.4), 2.86 (s, 2H), 0.98 (s,
9H).
7-Amino-3,4-dihydro-4-(2,2,2-trifluoroethyl)-2H-1,4-benzox-
azine (9f, R1 ) CH2CF3, R3 ) H). Compound 9f (2.7 g, 98%)
was prepared from 8f (3.12 g, 12 mmol). Rf 0.47 (3:2 EtOAc/
(2R)-(+)-2-(2-Fluoro-4-nitrophenyl)amino-1-propanol (20a,
R2 ) Me). Compound 20a (68.4 g, 80%), a yellow solid, was
prepared from (R)-(-)-2-amino-1-propanol (30 g, 0.40 mol) and
sodium bicarbonate (33.6 g, 0.40 mol) in 120 mL of ethanol, after
recrystallization from ethanol: mp 128.2-129.7 °C; [R]D ) +22.6
1
hexanes); H NMR (400 MHz, CDCl3) δ 6.56 (d, 1H, J ) 8.2),
6.30-6.20 (m, 2H), 4.16 (t, 2H, J ) 4.3), 3.65 (q, 2H, J ) 9.1),
3.39 (t, 2H, J ) 4.4), 3.36 (br s, 1H).
1
(EtOH, c 3.1); H NMR (400 MHz, CDCl3) d 7.99 (dd, 1H, J )
(()-7-Amino-3,4-dihydro-2,4-dimethyl-2H-1,4-benzoxazine (9
g, R1 ) Me, R3 ) Me). Compound 9g (134 mg, 97%) was prepared
from 8g (160 mg, 0.77 mmol). Rf 0.35 (11.5:1 CH2Cl2/MeOH); 1H
NMR (400 MHz, CDCl3) δ 6.54 (d, 1H, J ) 8.0), 6.25-6.20 (m,
2H), 4.36-4.33 (m, 1H), 3.31 (br s, 2H), 3.08 (dd, 1H, J ) 11.4,
2.3), 2.82 (dd, 1H, 11.4, 8.2), 2.78 (s, 3H), 1.33 (d, 3H, J ) 6.2).
(()-7-Amino-3,4-dihydro-2-methyl-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (9h, R1 ) CH2CF3, R3 ) Me). Compound
9h (345 mg (98%) was prepared from 8h (394 mg, 1.4 mmol). Rf
0.60 (11.5:1 CH2Cl2/MeOH); 1H NMR (400 MHz, CDCl3) δ 6.57
(d, 1H, J ) 9.2), 6.27-6.22 (m, 2H), 6.24 (s, 1H), 4.18 (m, 1H),
3.75-3.62 (m, 3H), 3.27 (dd, 1H, J ) 12.0, 9.8), 3.10 (dd, 1H, J
) 12.0, 8.5), 1.34 (d, 3H, J ) 6.3).
11.4), 7.89 (dd, 1H, J ) 11.6, 2.5), 6.72 (dd, 1H, J ) 8.7), 4.75
(br s, 1H), 3.8 (m, 2H), 3.69 (m, 1H), 1.31 (d, 3H, J ) 6.4).
(2R)-2-(2-Fluoro-4-nitrophenyl)amino-1-butanol (20b, R2 )
Et). Compound 20b (9.9 g, 99%), a yellow oil, was prepared from
(R)-(-)-2-amino-1-butanol (4.14 mL, 0.044 mol) in 133 mL of
anhydrous DMF heated at 90 °C, after flash chromatography
1
(gradient elution, hexanes/ethyl acetate 95:5 to 50:50). H NMR
(500 MHz, CDCl3) δ 7.98 (dd, 1H, J ) 8.8, 1.5), 7.89 (dd, 1H, J
) 11.7, 2.4), 6.71 (dd, 1H, J ) 8.8, 8.8), 4.72 (br s, 1H), 3.81 (m,
1H), 3.73 (m, 1H), 3.55 (m, 1H), 1.76 (m, 1H), 1.63 (m, 1H), 1.02
(t, 3H, J ) 7.8).
(2R)-2-(2-Fluoro-4-nitrophenyl)amino-3-methyl-1-butanol (20c,
R2 ) Isopropyl). Compound 20c (8.3 g (71%), a yellow solid,

2492 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10
Higuchi et al.
was prepared from (R)-(-)-2-amino-3-methyl-1-butanol (5.00 g,
48.5 mmol) in 6 mL of EtOH heated at reflux for 22 h, after flash
chromatography. Rf 0.8 (1:1 hexanes/EtOAc); 1H NMR (400 MHz,
CDCl3) δ 8.00-7.96 (m, 1H), 7.90 (dd, 1H, J ) 11.6, 2.4), 6.73
(dd, 1H, J ) 8.5, 8.5), 4.75-4.69 (m, 1H), 3.87-3.79 (m, 1H),
3.79-3.70 (m, 1H), 3.47-3.39 (m, 1H), 2.06-1.97 (m, 1H), 1.03
(d, 3H, J ) 3.6), 1.01 (d, 3H, J ) 3.6).
2H), 6.96-6.88 (m, 1H), 5.81 (q, 1H, minor diast., J ) 4.7), 5.69
(q, 1H, major diast., J ) 4.7), 4.45-4.40 (m, minor diast., 1H),
4.36-4.28 (m, major diast., 1H), 4.11-4.01 (m, 2H), 1.82-1.74
(m, 1H), 1.66-1.52 (m, 2H), 1.02 (d, 3H, major diast., J ) 6.4),
0.99-0.95 (m, 3H), 0.91 (d, 3H, minor diast., J ) 6.6).
(2R)-(-)-2-[2-Fluoro-4-nitro(2,2,2-trifluoroethyl)anilino]-1-
propanol (22a, R2 ) Me). A solution of cis-21a and trans-21a
(93 g, 0.36 mole), 600 mL of dry chloroform, and triethylsilane
(183.7 g, 1.58 mol) was cooled to -78 °C and TiCl4 (90 g, 0.474
mol) was added via addition funnel. The reaction mixture was
allowed to warm to room temperature and stirred for another 24 h.
The mixture was quenched with ice and then neutralized with
(2R)-2-(2-Fluoro-4-nitrophenyl)amino-4-methyl-1-pentanol (20d,
R2 ) Isobutyl). Compound 20d (6.0 g (55%), a yellow solid, was
prepared from (R)-(-)-2-amino-4-methyl-1-pentanol (5.00 g, 42.7
mmol) in EtOH heated at reflux for 16 h, after flash chromatography
(gradient elution, hexanes/EtOAc 9:1 to 1:1). Rf 0.3 (3:1 hexanes/
1
EtOAc); H NMR (400 MHz, CDCl3) δ 8.01-7.97 (m, 1H), 7.90
aqueous Na2CO3. The organic layers were washed with water and
brine, dried over MgSO4, filtered, and concentrated. The residue
(dd, 1H, J ) 11.7, 2.7), 6.74 (dd, 1H, J ) 8.6, 8.6), 4.62-4.57 (m,
1H), 3.82-3.74 (m, 1H), 3.75-3.62 (m, 2H), 1.77-1.65 (m, 1H),
1.61-1.45 (m, 2H), 0.99 (d, 3H, J ) 6.6), 0.93 (d, 3H, J ) 6.6).
General Procedure 6: Formation of an Oxazolidine from an
Aminoalcohol and Trifluoroacetaldehyde Ethyl Hemiacetal. A
round-bottom flask equipped with a Dean-Stark condenser was
charged with the amino alcohol (1 equiv), benzene (0.3-0.5 M),
trifluoroacetaldehyde ethyl hemiacetal (5 equiv), and p-toluene-
sulfonic acid (catalytic). The reaction mixture was refluxed with
azeotropic removal of water for 10-12 h. After cooling to room
temperature, the reaction mixture was concentrated under reduced
pressure. The residue was dissolved in ethyl acetate, washed with
aqueous sodium bicarbonate and brine, and dried over anhydrous
MgSO4. After filtration, the solvents were removed under reduced
pressure to afford the desired oxazolidine. In most instances, the
oxazolidine was isolated as a diastereomeric mixture and carried
on directly.
was purified by silica gel column chromatography (ethyl acetate/
hexanes 1:9) to afford 57 g (61%) of 22a, as a glassy solid. [R]D
) -205.9 (EtOH, c 10.15); 1H NMR (CDCl3) δ 7.99 (dd, 1H, J )
2.5, 9.0), 7.95 (dd, 1H, J ) 2.6, 14.7), 7.32 (dd, 1H, J ) 8.6), 3.94
(m, 1H), 3.74 (m, 2H), 3.65 (m, 1H), 1.86 (br s, 1H), 1.19 (d, 3H,
J ) 6.7).
(2R)-2-[2-Fluoro-4-nitro(2,2,2-trifluoroethyl)anilino]-1-bu-
tanol (22b, R2 ) Et). To a solution of 21b (9.2 g, 29.8 mmol) and
Et3SiH (19.1 mL, 119 mmol) in 100 mL of chloroform was added
BF3OEt2 (7.56 mL, 60 mmol). The reaction was heated to reflux
for 12 h, then additional BF3OEt2 (7.56 mL, 60 mmol) was added,
and the mixture was heated at reflux for an additional 12 h. After
cooling, MeOH (5 mL) was added, and after 1 h, the reaction was
poured in water (250 mL) and extracted with ethyl acetate (3 ×
250 mL). The organic layers were combined, washed with water
(250 mL) and brine (250 mL), dried (MgSO4), filtered, and
concentrated under reduced pressure to afford a brown oil. Flash
chromatography (gradient elution, hexanes/ethyl acetate 95:5 to 50:
cis-(2S,4R)-(-)-3-(2-Fluoro-4-nitrophenyl)-4-methyl-2-trifluo-
romethyloxazolidine (cis-21a, R2 ) Me) and trans-(2R,4R)-(+)-
3-(2-Fluoro-4-nitrophenyl)-4-methyl-2-trifluoromethyloxazoli-
dine (trans-21a, R2 ) Me). These compounds were prepared from
20a (68 g, 0.317 mole) and 100 mg of p-toluenesulfonic acid (100
mg, 0.53 mmol) to afford 21a as a low melting solid. The product
is a mixture of two diastereoisomers (cis/trans 4:1). Crystallization
from ethyl acetate-hexanes furnished the major (cis-21a) isomer
as pale yellow needles and the minor (trans-21a) isomer as a glassy
solid. In subsequent examples, the compounds are carried on as
mixtures of diastereomers. The combined yield of both compounds
was 93.2 g (100%).
1
50) afforded 5.4 g (59%) of 22b. H NMR (500 MHz, CDCl3) δ
7.98 (dd, 1H, J ) 8.8, 2.4), 7.94 (dd, 1H, J ) 13.2, 2.9), 7.37 (dd,
1H, J ) 8.8, 8.8), 4.12 (m, 1H), 3.87 (m, 1H), 3.77 (m, 1H), 3.70
(m, 1H), 3.57 (m, 1H), 1.78 (dd, 1H, J ) 6.8, 4.4), 1.50-1.60 (m,
2H), 0.95 (t, 3H, J ) 7.3).
(2R)-2-[2-Fluoro-4-nitro(2,2,2-trifluoroethyl)anilino]-3-meth-
yl-1-butanol (22c, R2 ) Isopropyl). To a solution of 21c (1.8 g,
5.6 mmol) and Et3SiH (1.88 g, 16.1 mmol) in 15 mL of CHCl3
was added TiCl4 (6 mL of a 1 M solution in CH2Cl2, 6 mmol) at
-78 °C. The solution was stirred for 2 h, then allowed to warm to
0 °C, and stirred for 2 h. The mixture was poured into 150 mL of
water and neutralized with 6 N NaOH. The aqueous layer was
extracted with CHCl3 (3 × 100 mL), and the combined organic
layers were washed with brine (150 mL), dried over MgSO4,
filtered, and concentrated. Flash chromatography (gradient elution,
hexanes/EtOAc 9:1 to 3:1) afforded 1.6 g (88%) of 22c, an orange
cis-21a: mp 46-50 °C; [R]D ) -60.9 (CHCl3, c 10.3); 1H NMR
(CDCl3) δ 8.01 (m, 1H), 7.98 (dd, 1H, J ) 12.3, 2.5), 6.96 (dd,
1H, J ) 9.0), 5.75 (q, 1H, J ) 4.7), 4.33 (m, 1H), 4.19 (m, 1H),
3.99 (m, 1H), 1.45 (d, 3H, J ) 6.3).
1
trans-21a: [R]D ) +258.9 (CHCl3, c 8.25); H NMR (CDCl3)
δ 8.02 (dd, 1H), 7.98 (dd, 1H, J ) 12.9, 2.5). 6.96 (dd, 1H, J )
8.5), 5.83 (q, 1H, J ) 4.7), 4.48 (m, 1H), 4.40 (m, 1H), 3.95 (m,
1H), 1.23 (d, 3H, J ) 6.0).
1
oil. Rf 0.3 (3:1 hexanes/EtOAc); H NMR (400 MHz, CDCl3) δ
7.96 (dd, 1H, J ) 8.8, 2.3), 7.92 (dd, 1H, J ) 13.4, 2.5), 7.37 (dd,
1H, J ) 8.8, 8.8), 4.33-4.23 (m, 1H), 4.03-3.86 (m, 2H), 3.81-
3.74 (m, 1H), 3.36-3.27 (m, 1H), 1.97-1.88 (m, 1H), 1.85 (br s,
1H), 0.99 (d, 3H, J ) 6.6), 0.94 (d, 3H, J ) 6.6).
(4R)-3-(2-Fluoro-4-nitrophenyl)-4-ethyl-2-(trifluoromethyl)-
1,3-oxazolidine (21b, R2 ) Et). Compound 21b (1.8 g, 85%) was
prepared from 20b (1.6 g, 70 mmol) and p-toluenesulfonic acid
(0.13 g, 0.68 mmol) in 70 mL anhydrous benzene, after flash chroma-
tography (gradient elution, hexanes/ethyl acetate 90:10 to 50:50).
1H NMR (500 MHz, CDCl3) δ 8.01 (m, 1H), 7.98 (m, 1H), 6.95
(dd, 1H, J ) 8.8, 8.8), 5.68 (m, 1H), 4.30 (m, 1H), 4.08 (m, 1H),
3.92 (m, 1H), 2.00 (m, 1H), 1.67 (m, 1H), 0.97 (t, 3H, J ) 7.8).
(4R)-3-(2-Fluoro-4-nitrophenyl)-4-isopropyl-2-(trifluoromethyl)-
1,3-oxazolidine (21c, R2 ) Isopropyl). Compound 21c (5.2 g,
47%) was prepared from 20c (8.3 g, 34 mmol) and p-toluenesulfonic
acid (20 mg, 0.10 mmol) in 220 mL benzene. Rf 0.7 (3:1 hexanes/
(2R)-2-[2-Fluoro-4-nitro(2,2,2-trifluoroethyl)anilino]-4-meth-
yl-1-pentanol (22d, R2 ) Isobutyl). To a solution of 21d (4.8 g,
14.3 mmol) and Et3SiH (21.6 g, 186 mmol) in 60 mL of CHCl3
was added BF3OEt2 (14.2, 60 mmol). The reaction was heated at
reflux for 1 day. After cooling, the reaction was poured in water
(200 mL) and extracted with CHCl3 (3 × 150 mL). The organic
layers were combined, washed sequentially with water (200 mL)
and brine (200 mL), dried (MgSO4), filtered, and concentrated under
reduced pressure to afford a brown oil. Flash chromatography
(gradient elution, hexanes/ethyl acetate 95:5 to 3:1) afforded 2.1 g
(44%) of 22d, an orange oil. Rf 0.8 (3:1 hexanes/EtOAc); 1H NMR
(400 MHz, CDCl3) δ 7.98 (dd, 1H, J ) 9.3, 2.4), 7.94 (dd, 1H, J
) 12.9, 2.5), 7.40 (dd, 1H, J ) 8.7, 8.7), 4.21-4.10 (m, 1H), 3.89-
3.78 (m, 1H), 3.79-3.65 (m, 3H), 1.96-1.89 (m, 1H), 1.67-1.54
(m, 1H), 1.55-1.44 (m, 1H), 1.32-1.22 (m, 1H), 0.91 (d, J ) 6.6,
3H), 0.77 (d, J ) 6.6, 3H).
1
EtOAc); H NMR (400 MHz, CDCl3) δ 8.04-7.97 (m, 2H), 7.22
(dd, J ) 8.7, 8.7, 1H), 5.34 (q, J ) 4.6, 1H), 4.27 (dd, J ) 8.0,
8.0, 1H), 4.11(dd, J ) 7.4, 7.4, 1H), 3.81 (q, J ) 7.1, 1H), 2.02-
1.93 (m, 1H), 0.96 (d, J ) 6.8, 6H).
(4R)-3-(2-Fluoro-4-nitrophenyl)-4-isobutyl-2-(trifluoromethyl)-
1,3-oxazolidine (21d, R2 ) Isobutyl). Compound 21d (5.15 g,
65%) was prepared from 20d (6.0 g, 23 mmol) and p-toluene-
sulfonic acid (0.020 g, 0.10 mmol) in 250 mL benzene. Rf 0.8 (3:1
General Procedure 7: Intramolecular Benzoxazine Cycliza-
tion. A solution of the aminoalcohol (1 equiv) in dry THF (1 M)
1
hexanes/EtOAc); H NMR (400 MHz, CDCl3) δ 8.03-7.94 (m,

Nonsteroidal SelectiVe Androgen Receptor Modulators
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10 2493
was added to a suspension of NaH (1.5 equiv) in dry THF (2 M),
and the mixture was heated at reflux for 3 h or until TLC indicated
the reaction was completed. After cooling, methanol (50 mL/mol)
was added. The reaction mixture was poured into cold water and
extracted with ethyl acetate. The organic portions were combined,
washed with brine, and dried over MgSO4. After filtration, the
solvents were evaporated under reduced pressure and purified as
indicated.
g, 65%) was prepared according to General Procedure 3 (Pd-C
reduction) from 24c (0.22 g, 0.69 mmol) and 10% Pd/C (0.075 g)
in 5 mL ethyl acetate. Rf 0.3 (3:1 hexanes/EtOAc); 1H NMR (400
MHz, CDCl3) δ 6.63 (d, 1H, J ) 8.5), 6.27 (dd, 1H, J ) 8.5, 2.6),
6.23 (d, 1H, J ) 2.5), 4.10 (dd, 1H, J ) 10.6, 1.8), 3.97 (dd, 1H,
J ) 10.6, 2.3), 3.70-3.51 (m, 2H), 3.38 (br s, 2H), 3.19-3.13 (m,
1H), 1.75-1.63 (m, 1H), 1.47-1.25 (m, 2H), 0.93 (d, 3H, J )
6.6), 0.89 (d, 3H, J ) 6.6).
(3R)-(+)-3,4-Dihydro-3-methyl-7-nitro-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (23a, R2 ) Me). Compound 23a (36.5 g,
68%), a yellow crystalline solid, was prepared from 22a (57 g,
0.193 mol), heated at reflux for 3 h, after purification by flash
chromatography. Mp 95.5-96.4 °C; [R]D ) +57.8 (EtOH, c 2.25);
1H NMR (CDCl3) δ 7.80 (dd, 1H, J ) 9.1, 2.5), 7.73 (d, 1H, J )
2.6), 6.71 (d, 1H, J ) 9.1), 4.13 (m, 2H), 4.03 (m, 1H), 3.84 (m,
1H), 3.69 (m, 3H), 1.31 (d, 3H, J ) 6.6).
General Procedure 8: Condensation of a 7-Amino-3,4-
dihydro-2H-1,4-benzoxazine with Ethyl 4,4,4-Trifluoroacetoac-
etate Followed by Treatment with Polyphosphoric Acid or
Sulfuric Acid (Knorr Reaction). To a solution of a 7-amino-3,4-
dihydro-2H-1,4-benzoxazine (1.0 equiv) in benzene (10 mL/mmol)
under N2 at room temperature was added ethyl 4,4,4-trifluoroac-
etoacetate (1.2 equiv), and the reaction was heated at reflux for
12-16 h, whereupon the mixture was concentrated under reduced
pressure. The crude reaction mixture was diluted in PPA (8 mL/
mmol) or concd sulfuric acid (2-3 mL/mmol) and heated to 100
°C for 12-16 h. The resulting mixture was poured over ice,
neutralized with 6 M NaOH solution to pH 7.0, extracted with CH2-
Cl2 (3 × 30 mL/mmol), and washed with pH 7 phosphate buffer
(50 mL/mmol) and brine (50 mL/mmol). The organic solution was
dried (MgSO4) and concentrated under reduced pressure. Purifica-
tion by flash chromatography (silica gel, 20:1, CH2Cl2/MeOH, or
as otherwise indicated) afforded the desired quinolone as a yellow
solid.
1,2,3,6-Tetrahydro-1-methyl-9-(trifluoromethyl)-7H-[1,4]ox-
azino[3,2-g]quinolin-7-one (10a, R1 ) Me, R3 ) H). Compound
10a (125 mg, 44%) was prepared from 9a mg, 0.98 mmol). Rf 0.44
(EtOAc); 1H NMR (400 MHz, CDCl3) δ 10.65 (br s, 1H), 6.90 (s,
1H), 6.87 (s, 1H), 6.72 (s, 1H), 4.39 (t, 2H, J ) 4.6), 3.31 (t, 2H,
J ) 4.5), 2.94 (s, 3H).
1-Ethyl-1,2,3,6-tetrahydro-9-(trifluoromethyl)-7H-[1,4]oxazino-
[3,2-g]quinolin-7-one (10b, R1 ) Et, R3 ) H). Compound 10b
(100 mg, 35%) was prepared from 9b (170 mg, 0.95 mmol). Rf
0.21 (11.5:1 CH2Cl2/MeOH); 1H NMR (400 MHz, CDCl3) δ 11.47
(br s, 1H), 6.92 (s, 1H), 6.88 (s, 1H), 6.81 (s, 1H), 4.35 (t, 2H, J
) 4.5), 3.4 (q, 2H, J ) 7.1), 3.34 (t, 2H, J ) 4.5), 1.19 (t, 3H, J
) 7.1). Anal. (C14H13F3N2O2): C, H, N.
(3R)-3-Ethyl-3,4-dihydro-7-nitro-4-(2,2,2-trifluoroethyl)-2H-
1,4-benzoxazine (23b, R2 ) Et). Compound 23b (3.78 g, 75%)
was prepared from 22b (5.4 g, 17.3 mmol) in 45 mL of THF and
NaH (1.4 g, 35 mmol) in 10 mL of THF, after purification by flash
chromatography (gradient elution, hexanes/ethyl acetate 95:5 to 50:
1
50). H NMR (500 MHz, CDCl3) δ 7.81 (dd, 1H, J ) 8.8, 2.4),
7.73 (d, 1H, J ) 2.9), 6.72 (d, 1H, J ) 8.8), 4.34 (dd, 1H, J )
11.2, 1.5), 4.13 (m, 1H), 4.03 (dd, 1H, J ) 11.2, 2.4), 3.8 (m, 1H),
3.37 (m, 1H), 1.67 (m, 1H), 1.01 (t, 3H, J ) 7.3).
(3R)-3,4-Dihydro-3-isopropyl-7-nitro-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (23c, R2 ) Isopropyl). Compound 23c (0.80
g, 54%), a yellow oil, was prepared from 22c (1.58 g, 4.87 mmol),
after purification by flash chromatography (gradient elution, hex-
anes/EtOAc 9:1 to 3:1). Rf 0.5 (3:1 hexanes/EtOAc); 1H NMR (400
MHz, CDCl3) δ 7.81 (dd, 1H, J ) 9.1, 2.5), 7.72 (d, 1H, J ) 2.6),
6.79 (d, 1H, J ) 9.1), 4.49 (dd, 1H, J ) 11.1, 0.92), 4.37-4.26
(m, 1H), 3.95 (dd, 1H, J ) 11.1, 2.4), 3.80-3.69 (m, 1H), 3.14 (d,
1H, J ) 8.5), 2.08-1.98 (m, 1H), 1.01 (d, 3H, J ) 6.9), 0.99 (d,
3H, J ) 6.9).
(3R)-3,4-Dihydro-3-isobutyl-7-nitro-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (23d, R2 ) Isobutyl). Compound 23d (0.87
g, 50%), a yellow oil, was prepared from 22d (1.95 g, 5.76 mmol).
1
Rf 0.6 (3:1 hexanes/EtOAc); H NMR (400 MHz, CDCl3) δ 7.79
(dd, 1H, J ) 9.1, 2.7), 7.71 (d, 1H, J ) 2.5), 6.72 (d, 1H, J ) 9.1),
4.30 (dd, 1H, J ) 11.0, 1.5), 4.19-4.06 (m, 1H), 4.06-4.01 (m,
1H), 3.82-3.73 (m, 1H), 3.53-3.47 (m, 1H), 1.71-1.61 (m, 2H),
1.38-1.29 (m, 1H), 0.99 (d, 3H, J ) 6.5), 0.96 (d, 3H, J ) 6.5).
(3R)-(-)-7-Amino-3,4-dihydro-3-methyl-4-(2,2,2-trifluoroeth-
yl)-2H-1,4-benzoxazine (24a, R2 ) Me). Compound 24a (31 g,
98%), an off-white solid, was prepared according to General
Procedure 3 (Pd-C reduction) from 23a (35.5 g, 0.128 mol) and
10% palladium on carbon (3 g) in 400 mL of ethyl acetate, after
purification by flash chromatography (ethyl acetate/hexanes). [R]D
) -39.4 (EtOH, c 1.7); 1H NMR (CDCl3) δ 6.58 (d, 1H, J ) 8.2),
6.40 (m, 1H), 6.37 (m, 1H), 4.05 (dd, 1H, J ) 11.0, 2.3), 3.98 (dd,
1H, J ) 10.6, 2.9), 3.66 (m, 2H), 3.38 (m, 1H), 3.40 (br s, 2H),
1.18 (d, 3H, J ) 6.6).
1,2,3,6-Tetrahydro-1-propyl-9-(trifluoromethyl)-7H-[1,4]ox-
azino[3,2-g]quinolin-7-one (10c, R1 ) Pr, R3 ) H). Compound
10c (100 mg, 16%) was prepared from 9c (395 mg, 2.0 mmol)
after purification by flash chromatography (3:2 EtOAc/hexanes)
and recrystallization from MeOH. Rf 0.24 (3:2 EtOAc/hexanes);
1H NMR (400 MHz, CDCl3) 11.79 (br s, 1H), 6.88 (s, 1H), 6.87
(s, 1H), 6.83 (s, 1H), 4.32 (t, 2H, J ) 4.5), 3.37 (t, 2H, J ) 4.5),
3.26 (t, 2H, J ) 7.4), 1.66 (sext, 2H, J ) 7.4), 0.99 (t, 3H, J )
7.4). HRMS (ESI) calcd for C15H16F3N2O2 (M + H)+, 313.1164;
found, 313.1150.
1,2,3,6-Tetrahydro-1-isobutyl-9-(trifluoromethyl)-7H-[1,4]ox-
azino[3,2-g]quinolin-7-one (10d, R1 ) Isobutyl, R3 ) H).
Compound 10d (241 mg (25%) was prepared from 9d (620 mg,
3.0 mmol) after purification by flash chromatography (3:2 EtOAc/
hexanes) and recrystallization from MeOH. Rf 0.2 (3:2 EtOAc/
hexanes); 1H NMR (400 MHz, CDCl3) δ 10.62 (br s, 1H), 6.87 (s,
2H), 6.74 (s, 1H), 4.31 (t, 2H, J ) 4.5), 3.41 (t, 2H, J ) 4.5), 3.05
(d, 2H, J ) 7.0), 2.05-1.95 (m, 1H), 0.98 (d, 6H, J ) 6.5). HRMS
(ESI) calcd for C16H18F3N2O2 (M + H)+, 327.1320; found,
327.1316. Anal. (C16H14F6N2O2): C, H, N.
(3R)-7-Amino-3-ethyl-3,4-dihydro-4-(2,2,2-trifluoroethyl)-2H-
1,4-benzoxazine (24b, R2 ) Et). Compound 24b (4.8 g, 95%)
was prepared according to General Procedure 3 (Pd-C reduction)
from 23b (5.6 g, 19.3 mmol) and 10% Pd/C (cat.) in 60 mL ethyl
acetate, and carried on without purification.
(3R)-7-Amino-3,4-dihydro-3-isopropyl-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (24c, R2 ) Isopropyl). Compound 24c
(0.284 g, 90%) was prepared according to General Produre 3 (Pd-C
reduction) from 23c (0.350 g, 1.15 mmol) and 10% Pd/C (0.14 g)
in 7 mL of EtOAc, after purification by flash chromatography
(gradient elution, hexanes/EtOAc 9:1 to 3:1). Rf 0.2 (3:1 hexanes/
1-(2,2-Dimethylpropyl)-1,2,3,6-tetrahydro-9-(trifluoromethyl)-
7H-[1,4]oxazino[3,2-g]quinolin-7-one (10e, R1 ) 2,2-Dimethyl-
propyl, R3 ) H). Compound 10e (20 mg, 24%) was prepared from
9e (53 mg, 0.24 mmol) after purification by flash chromatography
1
(3:2 EtOAc/hexanes). H NMR (400 MHz, CDCl3) δ 12.54 (br s,
1
EtOAc); H NMR (400 MHz, CDCl3) δ 6.71 (d, 1H, J ) 8.5),
1H), 7.03 (s, 1H), 6.89 (s, 1H), 6.88 (s, 1H), 4.31 (t, J ) 4.5, 2H),
3.42 (t, J ) 4.5, 2H), 3.06 (s, 2H), 1.02 s, 9H). HRMS (ESI) calcd
for C17H20F3N2O2 (M + H)+, 341.1477; found, 341.1477.
6.27 (dd, 1H, J ) 8.5, 2.6), 6.20 (d, 1H, J ) 2.5), 4.34 (dd, 1H, J
) 11.0, 1.5), 3.84 (dd, 1H, J ) 11.3, 2.2), 3.71-3.47 (m, 2H),
3.41 (br s, 2H), 2.62 (d, 1H, J ) 9.8), 1.81-1.70 (m, 1H), 0.98 (d,
3H, J ) 6.7), 0.96 (d, 3H, J ) 6.7).
1,2,3,6-Tetrahydro-1-(2,2,2-trifluoroethyl)-9-(trifluoromethyl)-
7H-[1,4]oxazino[3,2-g]quinolin-7-one (10f, R1 ) CH2CF3, R3 )
H). Compound 10f (790 mg, 19%) was prepared from 9f (2.7 g,
11.6 mmol) after purification by flash chromatography (3:2 EtOAc/
(3R)-7-Amino-3,4-dihydro-3-isobutyl-4-(2,2,2-trifluoroethyl)-
2H-1,4-benzoxazine (24d, R2 ) Isobutyl). Compound 24d (0.13

2494 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10
Higuchi et al.
hexanes) and recrystallization from MeOH. Rf 0.25 (11.5:1 CH2-
Cl2/MeOH); 1H NMR (400 MHz, CDCl3) δ 11.95 (br s, 1H), 7.04
(br s, 1H), 6.91 (s, 1H), 6.90 (s, 1H), 4.33 (t, 2H, J ) 4.5), 3.88 (q,
2H, J ) 8.9), 3.56 (t, 2H, J ) 4.5). Anal. (C14H10F6N2O2): C, H,
N.
(()-1,2,3,6-Tetrahydro-1,3-dimethyl-9-(trifluoromethyl)-7H-
[1,4]oxazino[3,2-g]quinolin-7-one (10g, R1 ) Me, R3 ) Me).
Compound 10g (50 mg, 40%) was prepared from 9g (75 mg, 0.42
mmol). Rf 0.42 (11.5:1 CH2Cl2/MeOH); 1H NMR (400 MHz,
CDCl3) δ 11.17 (br s, 1H), 6.88 (s, 1H), 6.87 (s, 1H), 6.78 (s, 1H),
4.45 (m, 1H), 3.24 (dd, 1H, J ) 11.7, 2.5), 3.02 (dd, 1H, J ) 11.5,
8.2), 2.93 (s, 3H), 1.40 (d, 3H, J ) 6.5).
(2R-)-(-)-1,2,3,6-Tetrahydro-2-methyl-1-(2,2,2-trifluoroethyl)-
9-(trifluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one [(R)-
16e, R1 ) CH2CF3, R2 ) Me]. (R)-16e (2.6 g, 42%) was prepared
from 24a (4.14 g, 16.8 mmol), after silica gel chromatography (ethyl
acetate/hexanes), followed by recrystallization from ethyl acetate-
hexanes. Mp 219-223 °C; [R]D ) -81.7 (EtOH, c 2.4); 1H NMR
(CDCl3) δ 7.05 (1H, s), 6.91 (1H, s), 6.89 (1H, s), 4.23 (dd, 1H, J
) 2.4, 10.8), 4.14 (dd, 1H, J ) 2.7, 10.7), 3.92 (1H, m), 3.78 (1H,
m), 3.61 (1H, m), 1.27 (d, 3H, J ) 6.6). 13C (100 MHz, DMSO-
d6) 160.0, 147.7, 135.6 (q, J ) 30.4), 134.3 (m), 129.9, 125.8 (q,
J ) 282), 122.7 (q, J ) 275), 118.4 (br s), 108.1, 106.0, 102.8, 68.8,
51.7, 50.9 (q, J ) 32.2), 15.0. Anal. (C15H12F6N2O2): C, H, N.
(2R)-2-Ethyl-1,2,3,6-tetrahydro-1-(2,2,2-trifluoroethyl)-9-(tri-
fluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one [(R)-16f, R1
) CH2CF3, R2 ) Ethyl]. (R)-16f (1.5 g, 21%) was prepared from
24b (4.8 g, 18.4 mmol), after flash chromatography (gradient
elution, hexanes/ethyl acetate 95:5 to 50:50), followed by additional
purification using reverse phase HPLC (Kromasil C18, 50 × 250
mm; 65:35 MeOH/water; flow rate of 80 mL/min). 1H NMR (500
MHz, CDCl3) δ 11.75 (br s, 1H), 7.06 (s, 1H), 6.91 (s, 1H), 6.89
(s, 1H), 6.89 (s, 1H), 4.34 (dd, J ) 10.7, 1.5, 1H), 4.14 (dd, J )
11.2, 2.4, 1H), 3.99 (m, 1H), 3.75 (m, 1H), 3.28 (m, 1H), 1.64 (dq,
J ) 7.6, 7.3, 2H), 1.00 (t, J ) 7.3, 3H). Anal. (C16H14F6N2O2): C,
H, N.
(2R)-1,2,3,6-Tetrahydro-2-isopropyl-1-(2,2,2-trifluoroethyl)-
9-(trifluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one [(R)-
16g, R1 ) CH2CF3, R2 ) Isopropyl]. (R)-16g (0.15 g, 38%) was
prepared from 24c (0.284 g, 1.04 mmol), after purification by flash
chromatography (19:1 CH2Cl2/MeOH). Further purification was
performed by reverse phase HPLC (ODS, 5 microm, 10 × 250
mm), 80% MeOH/water, 2.6 mL/min). Rf 0.2 (19:1 CH2Cl2/MeOH);
1H NMR (400 MHz, CDCl3) δ 12.52 (br s, 1H), 7.14 (br s, 1H),
6.95 (s, 1H), 6.92 (s, 1H), 4.50 (d, 1H, J ) 11.0), 4.18-4.06 (m,
1H), 4.05 (dd, 1H, J ) 11.0, 2.5), 3.75-3.60 (m, 1H), 2.98 (d, 1H,
J ) 8.7), 1.98-1.88 (m, 1H), 1.00 (d, 3H, J ) 7.3), 0.98 (d, 3H,
J ) 7.3). Anal. (C17H16F6N2O2): C, H, N.
(()-1,2,3,6-Tetrahydro-3-methyl-1-(2,2,2-trifluoroethyl)-9-
(trifluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one (10h, R1
) CH2CF3, R3 ) Me). Compound 10h (52 mg, 34%) was prepared
1
from 9h (345 mg, 1.4 mmol). Rf 0.26 (11.5:1 CH2Cl2/MeOH); H
NMR (400 MHz, CDCl3) δ 10.84 (br s, 1H), 7.05 (s, 1H), 6.90 (s,
1H), 6.82 (s, 1H), 4.35 (m, 1H), 3.91 (m, 1H), 3.83 (m, 1H), 3.44
(dd, 1H, J ) 12.1, 2.0), 3.21 (dd, 1H, J ) 11.7, 7.8), 1.42 (d, 3H,
J ) 6.2). Anal. (C15H12F6N2O2): C, H, N.
(()-3-Ethyl-1,2,3,6-tetrahydro-1-methyl-9-(trifluoromethyl)-
7H-[1,4]oxazino[3,2-g]quinolin-7-one (10i, R1 ) Me, R3 ) Et).
Compound 10i (26 mg, 20%) was prepared from 9i (80 mg, 0.4
mmol). Rf 0.19 (19:1 CH2Cl2/MeOH); 1H NMR (400 MHz, CDCl3)
δ 11.5 (br s, 1H), 6.89 (s, 2H), 6.83 (s, 1H), 4.22 (m, 1H), 3.26
(dd, 1H, J ) 11.6, 2.4), 3.05 (dd, 1H, J ) 11.6, 8.2), 2.94 (s, 3H),
1.76 (m, 1H), 1.67 (m, 1H), 1.08 (t, 3H, J ) 7.5).
(()-1,3-Diethyl-1,2,3,6-tetrahydro-9-(trifluoromethyl)-7H-
[1,4]oxazino[3,2-g]quinolin-7-one (10j, R1 ) Et, R3 ) Et).
Compound 10j (25 mg, 38%) was prepared from 9j (43 mg, 0.2
1
mmol). H NMR (400 MHz, CDCl3) δ 11.9 (br s, 1H), 6.90 (s,
1H), 6.89 (s, 1H), 6.86 (s, 1H), 4.10-4.20 (m, 1H), 3.45-3.55
(m, 1H), 3.25-3.35 (m, 1H), 3.26 (dd, J ) 11.9, 2.7, 1H), 3.10
(dd, J ) 11.9, 8.1, 1H), 1.60-1.80 (m, 2H), 1.19 (t, J ) 7.2, 3H),
1.08 (t, J ) 7.5, 3H). HRMS (ESI) calcd for C16H18F3N2O2 (M +
H)+, 327.1320; found, 327.1321.
(2R)-1,2,3,6-Tetrahydro-2-isobutyl-1-(2,2,2-trifluoroethyl)-9-
(trifluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one [(R)-16h,
R1 ) CH2CF3, R2 ) Isobutyl). (R)-16h (17 mg, 9%) was prepared
from 24d (0.13 g, 0.45 mmol), after purification by flash chroma-
tography (95:5 CH2Cl2/MeOH) and recrystallization from EtOAc/
hexanes. Rf 0.2 (19:1 CH2Cl2/MeOH); 1H NMR (400 MHz, CDCl3)
δ 12.58 (br s, 1H), 7.05 (br s, 1H), 6.97 (s, 1H), 6.91 (s, 1H), 4.30
(dd, 1H, J ) 11.0, 1.1), 4.16 (dd, 1H, J ) 11.0, 1.3), 4.01-3.91
(m, 1H), 3.75-3.65 (m, 1H), 3.42-3.37 (m, 1H), 1.71-1.62 (m,
1H), 1.62-1.54 (m, 1H), 1.35-1.27 (m, 1H), 0.96 (d, 3H, J )
6.9), 0.93 (d, 3H, J ) 7.5). HRMS (ESI) calcd for C18H20F6N2O2
(M + H)+, 409.1351; found, 409.1345.
(()-3-Ethyl-1,2,3,6-tetrahydro-1-(2,2,2-trifluoroethyl)-9-(tri-
fluoromethyl)-7H-[1,4]oxazino[3,2-g]quinolin-7-one (10k, R1 )
CH2CF3, R3 ) Et). Compound 10k (75 mg, 51%) was prepared
1
from 9k (100 mg, 0.38 mmol). Rf 0.18 (19:1 CH2Cl2/MeOH); H
NMR (400 MHz, CDCl3) δ 12.05 (br s, 1H), 7.03 (s, 1H), 6.95 (s,
1H), 6.92 (s, 1H), 4.15-4.05 (m, 1H), 3.98-3.88 (m, 1H), 3.88-
3.75 (m, 1H), 3.44 (dd, 1H, J ) 11.8, 2.5), 3.32 (dd, 1H, J ) 11.9,
8.1), 1.76 (m, 1H), 1.68 (m, 1H), 1.09 (t, 3H, J ) 7.6). Anal.
(C16H14F6N2O2): C, H, N.
1,2,3,6-Tetrahydro-9-(trifluoromethyl)-7H-[1,4]oxazino[3,2-
g]quinolin-7-one (11, R3 ) H). Compound 11 (533 mg, 30%) was
prepared from 9l (1.78 g, 6.58 mmol). Rf 0.17 (3:2 EtOAc/hexanes);
1H NMR (400 MHz, CDCl3) δ 10.73 (br s, 1H), 6.94 (s, 1H), 6.87
(s, 1H), 6.75 (s, 1H), 4.35 (t, 2H, J ) 4.4), 3.99 (br s, 1H), 3.50-
3.42 (m, 1H). HRMS (ESI) calcd for C12H10F3N2O2 (M + H)+,
271.0694; found, 271.0693.
(R)-2,3,3a,4-Tetrahydro-10-(trifluoromethyl)-1H-pyrrolo[1′,2′:
4,5][1,4]oxazino[3,2-g]quinolin-8(7H)-one [(R)-27]. (R)-27 (120
mg, 20%) was prepared from (R)-7-amino-2,3,3a,4-tetrahydro-1H-
pyrrolo[2,1-c][1,4]benzoxazine [(R)-25] (0.390 g, 2.05 mmol), after
purification by flash chromatography (92:8 CH2Cl2/MeOH). Further
purification was performed by reverse phase HPLC (ODS, 5 micron,
1-Cyclopropylmethyl-1,2,3,6-tetrahydro-9-(trifluoromethyl)-
7H-[1,4]oxazino[3,2-g]quinolin-7-one (12a, R1 ) Cyclopropyl-
methyl, R3 ) H). Compound 12a (64 mg, 98%) was prepared using
General Procedure 1 (reductive amination) from 11 (55 mg, 0.21
mmol), cyclopropanecarboxaldehyde (100 mg, 1.5 mmol), and
NaBH3CN (65 mg, 1.01 mmol). Rf 0.29 (19:1 CH2Cl2/MeOH); 1H
NMR (500 MHz, CDCl3) δ 11.04 (br s, 1H), 7.00 (s, 1H), 6.88 (s,
1H), 6.78 (s, 1H), 4.36 (t, 2H, J ) 4.4), 3.46 (t, 2H), J ) 4.4),
3.19 (d, 2H, J ) 6.3), 1.05 (m, 1H), 0.62-0.58 (m, 2H), 0.27 (m,
2H). HRMS (ESI) calcd for C16H16F3N2O2 (M + H)+, 325.1164;
found, 325.1158. Anal. (C16H15F3N2O2‚0.2H2O): C, H, N.
1-Benzyl-1,2,3,6-tetrahydro-9-(trifluoromethyl)-7H-[1,4]oxazino-
[3,2-g]quinolin-7-one (12b, R1 ) Benzyl, R3 ) H). Compound
12b (9 mg, 36%) was prepared using General Procedure 1 (reductive
amination) from 11 (19 mg, 0.07 mmol) and benzaldehyde. Rf 0.20
1
10 × 250 mm, 3 mL/min). H NMR (400 MHz, CDCl3) δ 11.42
(br s, 1H), 6.91 (s, 1H), 6.89 (s, 1H), 6.76 (br s, 1H), 4.54 (dd, 1H,
J ) 9.6, 2.7), 3.61 (t, 1H, J ) 9.6), 3.50-3.60 (m, 1H), 3.40-3.50
(m, 1H), 3.30-3.40 (m, 1H), 2.12-2.22 (m, 2H), 2.00-2.10 (m,
1H), 1.40-1.50 (m, 1H). Anal. (C15H13F3N2O2): C, H, N.
(()-1,2,3,4,4a,5-Hexahydro-11-(trifluoromethyl)-pyrido[1′,2′:
4,5][1,4]oxazino[3,2-g]quinolin-9(8H)-one (28). Compound 28
(0.110 g, 30%) was prepared from (()-3-amino-6,6a,7,8,9,10-
hexahydropyrido[2,1-c][1,4]benzoxazine (26; 0.232 g, 1.13). Rf 0.15
(2:3, EtOAc/hexanes); 1H NMR (400 MHz, CDCl3) δ 10.73 (br s,
1H), 7.09 (s, 1H), 6.87 (s, 1H), 6.73 (s, 1H), 4.26 (dd, 1H, J )
10.5, 2.6), 4.06 (dd, 1H, J ) 10.5, 9.0), 3.80 (m, 1H), 3.02-2.97
(m, 1H), 2.60 (td, 1H, J ) 12.2, 2.9), 1.92 (m, 2H), 1.74-1.65 (m,
2H), 1.50-1.42 (m, 1H), 1.29-1.21 (m, 1H). Anal. (C16H15F3N2O2‚
0.2 H2O): C, H, N.
1
(19:1 CH2Cl2/MeOH); H NMR (500 MHz, CDCl3) δ 11.2 (br s,
1H), 7.33 (m, 5H), 6.94 (s, 1H), 6.83 (s, 1H), 6.80 (s, 1H), 4.46 (s,
2H), 4.38 (t, 2H, J ) 4.5), 3.42 (t, 2H, J ) 4.5). HRMS (ESI)
calcd for C19H16F3N2O2 (M + H)+, 361.1164; found, 361.1165.
MDA Whole-Cell Binding Assay. Receptor binding assays for
hAR were performed in a whole cell format using MDA-MB-453

Nonsteroidal SelectiVe Androgen Receptor Modulators
Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10 2495
cells plated in DMEM+10% FBS in 96-well microtiter plates. Four
days after cell plating, the media were changed to DMEM+10%
charcoal-absorbed FBS (CA-FBS) to remove any endogenous ligand
complexed with hAR in the cells. After 24 h, either a saturation
analysis to determine the Kd for [3H]DHT on hAR or a competition
binding assay to evaluate the ability of test compounds to compete
with [3H]DHT for hAR was performed. For the saturation analysis,
media (DMEM+10% CA-FBS) containing [3H]DHT (1.8 - 0.04
nM) in the absence (total binding) or presence (nonspecific binding)
of a 100-fold molar excess of unlabeled DHT were added to the
cells. For the competition binding assay, media containing 0.3 nM
[3H]DHT and test compounds in concentrations ranging from 10-10
to 10-6 M were added to the cells. Three replicates were used for
each sample. After 3 h at 37 °C, an aliquot of the total binding
media at each concentration was removed to determine the amount
of free [3H]DHT. The media from the plates for the saturation
analysis and the competition binding assay was aspirated, and the
cells were washed twice with phosphate-buffered saline to remove
unbound ligand. Scintillation fluid (250 µL of Microscint 20,
Packard Instruments) was added to each well, and the amount of
[3H]DHT present was measured using a scintillation counter
(TopCount, Packard Instruments, CT). For the saturation analysis,
the difference between the total binding and nonspecific binding
was defined as specific binding, which was evaluated by Scatchard
analysis to determine the Kd for [3H]DHT. For the competition
binding assay, the amount of specific binding was determined for
each replicate as: (Total CPM Bound) - (Average Nonspecific
CPM Bound).
water mix was evaporated under nitrogen, and a 1% CMC solution
was added to complete the volume (9/10) of the formulation. The
high concentration formulation is then diluted using vehicle to
obtain the proper volumes.
Animals were treated orally via gavage each morning for the
next 28 days, with 4 mL/kg dosing with either control vehicle, (1),
or (R)-16e at various doses. Twenty-four h after the last dose, the
rats were sacrificed by decapitation and organs were collected. The
VP, SV, and LA muscle were dissected out, blotted dry, and
weighed individually. Serum was collected for determination of
serum LH levels.
Acknowledgment. We thank Catherine Gharbaoui for
performing mass spectrometry analyses on selected compounds,
Marquis L. Cummings for the chiral separation of compounds
10h and 16e-f, and Anthony W. Thompson for the preparation
of compound (R)-16f.
Supporting Information Available: Preparation of compounds
6b,c, 7a-c, (+)-10h, (-)-10h, 13, 16a-f, (S)-16e, (S)-16f, 25,
and 26, elemental and HPLC analyses, and the data analysis for
the 4-week castrated rat assay. This material is available free of
charge via the Internet at http://pubs.acs.org.
References
(1) Rosen, J.; Day, A.; Jones, T. K.; Jones, E. T.; Nadzan, A. M.; Stein,
R. B. Intracellular receptors and signal transducers and activators of
transcription superfamilies: Novel targets for small-molecule drug
discovery. J. Med. Chem. 1995, 38, 4855-4874.
(2) Bagatell, C. J; Bremner, W. J. Androgens in mensUses and abuses.
N. Engl. J. Med. 1996, 334, 707-714.
(3) (a) Bhasin, S.; Storer, T. W.; Berman, N.; Yarasheski, K. E.;
Clevenger, B.; Phillips, J.; Lee, W. P.; Bunnel, T. J.; Casaburi, R.
Testosterone replacement increases fat-free mass and muscle size in
hypogonadal men. J. Clin. Endocrinol. Metab. 1997, 82, 407-413.
(b) Handelsman, D. J.; Liu, P. Y. Andropause: Invention, prevention,
rejuvenation. Trends Endocrinol. Metab. 2005, 16, 39-45. (c) Bhasin,
S.; Woodhouse, L.; Casaburi, R.; Singh, A. B.; Mac, R. P.; Lee, M.;
Yarasheski, K. E.; Sinha-Hikim, I.; Dzekov, J.; Magliano, L.; Storer,
T. W. Older men are as responsive as young men to the anabolic
effects of graded doses of testosterone on skeletal muscle. J. Clin.
Endocrinol. Metab. 2005, 90, 678-688. (d) Zacharin, M. R.; Pua,
J.; Kanumakala, S. Bone mineral density outcomes following long-
term treatment with subcutaneous testosterone pellet implants in male
hypogonadism. Clin. Endocrinol. 2003, 58, 691-695.
Nonspecific binding is defined as that binding remaining in the
presence of an excess of unlabeled specific ligand (i.e., 1000 nM
of unlabeled DHT). After correcting for nonspecific binding, IC50
values were determined. The IC50 value is defined as the concentra-
tion of competing ligand required to decrease specific binding by
50%. The IC50 value was determined with the aid of the log-logit
(Hill) method, which linearized the concentration response curve.
Linear regression was then used to determine the IC50 value. The
Ki values were determined by the application of the Cheng-Prusoff
equation to the IC50 values, using previously determined Kd values
for each specific ligand.18
Ki ) IC50/(1 + [L]/Kd)
where [L] ) the concentration of labeled ligand and Kd ) the
dissociation constant of the labeled ligand determined in the
saturation analysis.
PR, GR, and MR Binding Assays. The procedure for the cross-
reactivity receptor binding assays using baculovirus-expressed
receptors was previously described.19 The radioligands used in the
competitive receptor binding assays are progesterone for hPR-A,
dexamethasone for hGR, and aldosterone for hMR.
(4) Negro-Vilar, A.; Selective androgen receptor modulators (SARMs):
A novel approach to androgen therapy for the new millennium. J.
Clin. Endocrinol. Metab. 1999, 84, 3459-3462.
(5) Liu, P. Y.; Handelsman, D. J. Androgen Therapy in Non-Gonadal
Disease. In Testosterone Action, Deficiency, Substitution, 3rd edition;
Nieschlag, E., Behre, H. M., Eds.; Cambridge University Press: New
York, 2004; pp 446-472.
(6) Marhefka, C. A.; Gao, W.; Chung, W.; Kim, J.; He, Y.; Yin, D.;
Bohl, C.; Dalton, J. T.; Miller, D. D. Design, synthesis, and biological
characterization of metabolically stable selective androgen receptor
modulators. J. Med. Chem. 2004, 47, 993-998. (b) Bohl, C. E.;
Chang, C.; Mohler, M. L.; Chen, J.; Miller, D. D.; Swaan, P. W.;
Dalton, J. T. A ligand-based approach to identify quantitative
structure-activity relationships for the androgen receptor. (c) Gao,
W.; Bohl, C. E.; Dalton, J. T. Chemistry and structural biology of
androgen receptor. Chem. ReV. 2005, 105, 3352-3370.
(7) (a) Sun, C.; Robl, J. A.; Wang, T. C.; Huang, Y.; Kuhns, J. E.;
Lupisella, J. A.; Beehler, B. C.; Golla, R.; Sleph, P. G.; Seethala,
R.; Fura, A.; Krystek, S. R.; An, Y.; Malley, M. F.; Sack, J. S.;
Salvati, M. E.; Grover, G. J.; Ostrowski, J.; Hamann, L. G. Discovery
of potent, orally-active, and muscle-selective androgen receptor
modulators based on an N-aryl-hydroxybicyclohydantoin scaffold.
J. Med. Chem. 2006, 49, 7596-7599. (b) Zhang, X.; Allan, G. F.;
Sbriscia, T.; Linton, O.; Lundeen, S. G.; Sui, Z. Synthesis and SAR
of novel hydantoin derivatives as selective androgen receptor
modulators. Bioorg. Med. Chem. Lett. 2006, 16, 5763-5766. (c)
Lanter, J. C.; Fiordeliso, J. J.; Allan, G. F.; Musto, A.; Hahn, D. W.;
Sui, Z. Bioorg. Med. Chem. Lett. 2006, 16, 5646-5649. (d) Hanada,
K.; Furuya, K;, Yamamoto, N.; Nejishima, H.; Ichikawa, K.;
Nakamura, T.; Miyakawa, M.; Amano, S.; Sumita, Y.; Oguro, N.
Bone anabolic effects of S-40503, a novel nonsteroidal selective
androgen receptor modulator (SARM), in rat models of osteoporosis.
Biol. Pharm. Bull. 2003, 26, 1563-1569.
Four-Week Mature Castrated Rat Assay. Mature (approxi-
mately 8 weeks old; weighing 200 g) male Sprague-Dawley rats
from Harlan (Indianapolis, IN) were housed 2-3 per cage under
controlled lighting conditions on a 12-h cycle, with the lights on at
0600. Rat chow (Harlan Teklad 8604) and water were available ad
libitum. Mature male rats arrived and were castrated under
isoflurane anesthesia after a one-week acclimation period. One
group of animals was sham-operated and treated with vehicle and
served as one control group. After surgery, the rats were sorted
into groups of five such that no statistically significant differences
in body weight were observed. They began receiving treatment the
same day of the surgery after the surgical procedure. The
compounds were suspended in a vehicle of 9.995% polyethylene
glycol (PEG-400; Sigma), 0.005% Tween 80 (Sigma), and 90.0%
of a 1% carboxymethylcellulose (CMC; Sigma) solution in Nan-
oPure water. The appropriate amount of (R)-16e for the highest
concentration to be gavaged was weighed out and dissolved
completely into absolute ethanol. A mixture of 99.5% PEG 400
and 0.5% Tween 80 was added to the ethanol mixture to a total
1
volume of /10 the final volume. Water was added to the organic
mix in a sufficient volume to precipitate the drug. The alcohol/

2496 Journal of Medicinal Chemistry, 2007, Vol. 50, No. 10
Higuchi et al.
(8) (a) Hamann, L. G.; Mani, N. S.; Davis, R. L.; Wang, X.-N.; Marschke,
K. B.; Jones, T. K. Discovery of a potent, orally active nonsteroidal
androgen receptor agonist: 4-Ethyl-1,2,3,4-tetrahydro-6-(trifluoro-
methyl)-8-pyridono[5,6-g]quinoline (LG121071). J. Med. Chem.
1999, 42, 210-212. (b) Higuchi, R. I.; Edwards, J. P.; Caferro, T.
R.; Ringgenberg, J. D.; Kong, J. W.; Hamann, L. G.; Arienti, K. L.;
Davis, R. L.; Farmer, L. J.; Jones, T. K. 4-Alkyl- and 3,4-dialkyl-
1,2,3,4-tetrahydro-8-pyridono[5,6-g]quinolines: Potent, nonsteroidal
androgen receptor agonists. Bioorg. Med. Chem. Lett. 1999, 9, 1335-
1340. (c) Edwards, J. P.; Higuchi, R. I.; Winn, D. T.; Pooley, C. L.
F.; Caferro, T. R.; Hamann, L. G.; Zhi, L.; Marschke, K. B.;
Goldman, M. E.; Jones, T. K. Nonsteroidal androgen receptor agonists
based on 4-(trifluoromethyl)-2H-pyrano[3,2-g]quinolin-2-one. Bioorg.
Med. Chem. Lett. 1999, 9, 1003-1008. (d) Zhi, L.; Tegley, C. M.;
Marschke, K. B.; Jones, T. K. Switching androgen receptor antago-
nists to agonist by modifying C-ring substituents on piperidino[3,2-
g]quinolinone. Bioorg. Med. Chem. Lett. 1999, 9, 1009-1012.
(9) Hamann, L. G.; Higuchi, R. I.; Zhi, L.; Edwards, J. P.; Wang, X.-
N.; Marschke, K. B.; Kong, J. W.; Farmer, L. J.; Jones, T. K.
Synthesis and biological activity of a novel series of nonsteroidal,
peripherally selective androgen receptor antagonists derived from 1,2-
dihydropyridono[5,6-g]quinolines. J. Med. Chem. 1998, 41, 623-
639.
(13) Matsumoto, Y.; Tsuzuki, R.; Matsuhisa, A.; Takayama, K.; Yoden,
T.; Uchida, W.; Asano, M.; Fujita, S.; Yanagisawa, I.; Fujikura, T.
Novel potassium channel activators: Synthesis and structure-activity
relationship studies of 3,4-dihydro-2H-1,4-benzoxazine derivatives.
Chem. Pharm. Bull. 1996, 44, 103-114.
(14) (a) Kelly, T. R.; Field, J. A.; Li, Q. Synthesis of diazaquinomycin A
and B: The first double Knorr cyclization. Tetrahedron Lett. 1988,
29, 3545-3546. (b) Forbis, R. M.; Rinehart, K. L. Nybomycin. VII.
Preparative routes to nybomycin and deoxynybomycin. J. Am. Chem.
Soc. 1973, 95, 5003-5013.
(15) (a) From chiral epoxides: Xie, L. J. A facile synthesis of chiral
3-alkyl-3,4-dihydro-2H-1,4-benzoxazine derivatives. Chin. Chem.
Lett. 1995, 6, 857-860. (b) Baker’s yeast reduction: Kang, S. B.;
Ahn, E. J.; Kim, Y. A facile synthesis of (S)-(-)-7,8-difluoro-3,4-
dihydro-3-methyl-2H-1,4-benzoxazine by zinc chloride assisted Mit-
sunobu cyclization reaction. Tetrahedron Lett. 1996, 37, 9317-9320.
(16) Hall, R. E.; Birrell, S. N.; Tilley, W. D.; Sutherland, R. L. MDA-
MB-453, an androgen-responsive human breast carcinoma cell line
with high-level androgen receptor expression. Eur. J. Cancer 1994,
30, 484-490.
(17) Herschberger, L. G.; Shipley, E. G.; Meyer, R. K. Myotropic activity
of 19-nortestosterone and other steroids determined by modified
levator ani muscle method. Proc. Soc. Exp. Biol. Med. 1953, 83,
175-180.
(10) Unpublished results from our laboratories.
(11) (a) Van Oeveren, A.; Motamedi, M.; Mani, N. S.; Marschke, K. B.;
Lopez, F. J.; Schrader, W. T.; Negro-Vilar, A.; Zhi, L. Discovery of
6-N,N-bis(2,2,2-triflouroethyl)amino-4-trifluoromethylquinolin-2(1H)-
one as a novel selective androgen receptor modulator. J. Med. Chem.
2006, 49, 6143-6146. (b) Van Oeveren, A.; Motamedi, M.;
Martinborough, E.; Zhao, S.; Shen, Y.; West, S.; Chang, W.; Kallel,
A.; Marschke, K. B.; Lo´pez, F. J.; Negro-Vilar, A.; Zhi, L. Novel
selective androgen receptor modulators: SAR studies on 6-bisalkyl-
amino-2-quinolinones. Bioorg. Med. Chem. Lett. 2007, 17, 1527-
1531.
(18) Cheng, Y.-C.; Prusoff, W. H. Relationship between the inhibition
constant (Ki) and the concentration of inhibitor which causes a 50
percent inhibition (IC50) of an enzymatic reaction. Biochem. Phar-
macol. 1973, 22, 3099-3108.
(19) Pathirana, C.; Stein, R. B.; Berger, T. S.; Fenical, W.; Ianiro, T.;
Mais, D.; Torres, A.; Goldman, M. E.; Nonsteroidal human proges-
terone receptor modulators from the marine alga cymopolia barbata.
Mol. Pharmacol. 1995, 47, 630-635.
(12) Shridhar, D. R.; Jogibhukta, M.; Krishnan, V. S. H. A general and
convenient synthesis of 2H-1,4-benzoxazin-3(4H)-ones. Org. Prep.
Proced. Int. 1982, 14, 195-197.
JM061329J