Syntheses and structure-activity relationships of novel retinoid X receptor agonists

Article abstract of DOI:10.1021/jm980058c

As part of our studies to develop novel retinoids with increased affinity and selectivity for the retinoid X receptor (RXR) subfamily, we have designed and synthesized a series of (E,E,E)-7-(1,2,3,4-tetrahydroquinolin- 6-yl)-7-alkyl-6-fluoro-3-methylhepta-2,4,6-trienoic acid derivatives. These tetrahydroquinolines, generated by introducing a polar N atom into the hydrophobic part of the retinoid skeleton, showed high binding affinity to RXRs. Addition of fluorine at the 6-position of the 2,4,6-trienoic acid moiety afforded compounds which elicit potent and selective transactivation of the RXRs. Compound 14b (ER-35794), which possesses an ethyl substituent at the 7-position and fluorine at the 6-position of the triene moiety, is one of the most potent and selective RXR agonists reported to date.

Full text of DOI:10.1021/jm980058c

J . Med. Chem. 1998, 41, 3245-3252
3245
Syn th eses a n d Str u ctu r e-Activity Rela tion sh ip s of Novel Retin oid X Recep tor
Agon ists
Shigeki Hibi,* Kouichi Kikuchi, Hiroyuki Yoshimura, Mitsuo Nagai, Kenji Tai, and Takayuki Hida
Tsukuba Basic Research Laboratories, Eisai Co., Ltd., 1-3, Tokodai 5-chome, Tsukuba-shi, Ibaraki, 300-26, J apan
Received J anuary 26, 1998
As part of our studies to develop novel retinoids with increased affinity and selectivity for the
retinoid X receptor (RXR) subfamily, we have designed and synthesized a series of (E,E,E)-7-
(1,2,3,4-tetrahydroquinolin-6-yl)-7-alkyl-6-fluoro-3-methylhepta-2,4,6-trienoic acid derivatives.
These tetrahydroquinolines, generated by introducing a polar N atom into the hydrophobic
part of the retinoid skeleton, showed high binding affinity to RXRs. Addition of fluorine at
the 6-position of the 2,4,6-trienoic acid moiety afforded compounds which elicit potent and
selective transactivation of the RXRs. Compound 14b (ER-35794), which possesses an ethyl
substituent at the 7-position and fluorine at the 6-position of the triene moiety, is one of the
most potent and selective RXR agonists reported to date.
In tr od u ction
nicity and hypervitaminosis. A selective RXR agonist
1
5
(
LGD 1069 ) is under development for use in the
Retinoids play important roles in a variety of biologi-
cal processes, including mediation of cell growth and
differentiation in both normal and neoplastic cells. The
ability of retinoids to modulate proliferation and dif-
ferentiation of both normal and malignant cells in vitro
and in vivo has significant implications for the treat-
2
1
22
treatment of various cancers and diabetes (Chart 1).
In addition, it was recently reported that LGD 1069
showed an efficacy equivalent to that of tamoxifen as a
chemopreventive agent in a rat mammary carcinoma
1
2
3
model.
2
,3
In the course of our search for novel retinoids with
increased affinity and selectivity for the RXRs, we have
designed and synthesized a series of (E,E,E)-7-(1,2,3,4-
tetrahydroquinolin-6-yl)-7-alkyl-6-fluoro-3-methyl-hepta-
ment of dermatological diseases, such as psoriasis and
cancer, for which retinoids may have both chemothera-
peutic and chemopreventive applications.4-8
The retinoid receptors, members of the superfamily
of nuclear receptors, have been classified into two
subfamilies, the retinoic acid receptors (RARs) and the
retinoid X receptors (RXRs). These receptors function
as ligand-dependent transcription factors.1,9 The natu-
ral ligands for the RARs are all-trans-retinoic acid
2
,4,6-trienoic acid derivatives. These compounds were
evaluated for the ability to regulate gene expression and
to bind to retinoid receptors by using a transient
receptor/reporter cotransfection assay system in COS-1
2
4-26
3
cells
and a competitive binding assay with [ H]-9-
3
3
cis-retinoic acid ([ H]-9-cis-RA) and [ H]-all-trans-ret-
inoic acid ([ H]-ATRA) as radioligands.
(ATRA), 9-cis-retinoic acid (9-cis-RA), and 3,4-dehydro-
3
27
all-trans-retinoic acid, while 9-cis-retinoic acid (9-cis-
RA) is a potent activator of the RXRs.10 The classifi-
cation of the subfamilies is based primarily on differences
in amino acid sequence, responsiveness to synthetic
retinoids, and the ability to modulate expression of
different target genes. Each subfamily is made up of
three distinct subtypes designated RAR-R, â, and γ and
RXR-R, â, and γ.
RXRs form homodimers which bind to direct repeats
called retinoid X response elements. They also form
heterodimers with RARs as well as with other members
of the nuclear receptor superfamily, namely, the
peroxisome proliferator-activated receptors (PPARs), the
thyroid hormone receptor (TR), the vitamin D receptor
Dr u g Design
It is known that 9-cis-RA binds to and transactivates
both the RARs and RXRs. To obtain novel selective
RXR agonists, we planned to introduce a N atom into
the hydrophobic part of the molecule, since this was
found by the Roche group to reduce retinoid activi-
2
8,29
ties.
Since conformation is important for RXR
affinity, we introduced fluorine into the triene part in
order to stabilize the 9-cis form (Chart 2).
1
0
Ch em istr y
The general synthetic pathways for preparation of the
compounds listed in Table 3 are shown in Scheme 1.
Formylation of 1-(1-methylethyl)-1,2,3,4-tetrahydro-
quinoline (2), which was derived from 1,2,3,4-tetrahy-
droquinoline (1) by treatment with N,N-dimethylfor-
mamide and phosphorus oxychloride complex, afforded
only the 6-substituted carbaldehyde derivative (3),
which was transformed to the ketone derivative (5a ).
The olefination of the ketone derivative (5a ) with
triethyl phosphonoacetate was performed in the pres-
ence of an appropriate base, such as NaH, affording the
(VDR), and the orphan receptor (LXR). Only RAR-
1
1
specific ligands activate the RAR/RXR heterodimers,
whereas RXR/RXR homodimers are activated by RXR-
specific ligands.
1
2
A few RXR-selective retinoid agonists have been
reported.1
3-20
Such compounds are of interest because
they may elicit the beneficial pharmacological activities
of retinoids without toxic side effects such as teratoge-
*
Correspondence author. E-mail: s1-hibi@eisai.co.jp.
S0022-2623(98)00058-2 CCC: $15.00 © 1998 American Chemical Society
Published on Web 07/25/1998

3
246 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17
Hibi et al.
Ch a r t 1
ization to the to E isomer, so that the unstable (Z)-
butenal 8 could not be isolated.
To construct the stable 9-cis form, we used the
synthetic route employed for fluorinated vitamin A
3
0-35
analogues.
According to these reports, the Horner-
Emmons reaction using triethyl 2-fluoro-2-phospho-
noacetate for coupling with the ketone (5) should mainly
afford the E-form ester (11a -d ).
The configuration of the 2-fluorobutenoic ester (11)
was established by the magnitude of the four-bond H
(
3-Me), F coupling constants, and the proton chemical
3
3
1
shifts. The H NMR data for 11a , 12a , and 13a are
3
0
listed in Table 1. According to Pawson’s method, we
assigned the stereochemistry of the double bond from
the chemical shifts and coupling constants of the
intermediates (11a , 12a , and 13a ), and this assisted in
the assignment of the stereochemistry of the final
retinoids. In the esters 11 and the aldehyde 12, the
methyl group at C-3 of the Z isomers is deshielded, as
expected, by more than 0.17 ppm. We also found that
four-bond coupling constants ( J H- F) (Table 1) between
C-2 fluorine and C-3 methyl protons in compounds 11,
3
6
4
1
19
2, and 13 follow a pattern of J H-19F (E isomer) >
4
1
1
4
J 1H- F (Z isomer).
19
33,37
Horner-Emmons reaction of the R,â-unsaturated
aldehyde (12a -d ) afforded the 6-fluoro-3-methylhepta-
2
,4,6-trienoic acid ester (13a -d ), in which the major
Ch a r t 2
isomer had the 2E,4E,6E stereochemistry. This assign-
ment was based largely on the H NMR data for the
1
free acid derivatives (14), which were obtained by
hydrolysis of the esters (13) followed by crystallization
3
3
(Table 2).
Resu lt a n d Discu ssion
The above retinoids were evaluated in vitro for the
ability to bind the individual RARs and RXR-R and to
induce gene transcription in the cotransfection assay at
each of the six retinoid receptors. Binding assays for
receptor subtypes were performed in a manner similar
1
5
3
to that described by Boehm et al., using [ H]-9-cis-RA
3
as the radioligand for RXR-R and [ H]-ATRA for the
RARs. The relative IC50 values are reported based on
ATRA ) 1.0 for RARs, and 9-cis-RA ) 1.0 for RXR-R
(see Table 3). Cotransfection assays were performed as
described in the Experimental Section, with relative
EC30 values being reported (see footnote to Table 3). In
our investigation, it was found that the response to some
RAR-, and RXR-selective retinoids tended to reach a
plateau near 50% of that to the natural ligands.
Therefore, EC30 values were used to represent the
transcriptional activity for the evaluation of retinoid
derivatives, including low activity compounds.
E and Z isomers (6) in a ratio of approximately 85:15,
in a good yield. Reduction of the separated (E)-R,â-
unsaturated ester (6) with diisobutylaluminum hydride
(DIBAL-H) at -70 °C and oxidation with activated
manganese(IV) oxide afforded the (E)-R,â-unsaturated
aldehyde (8). The (E)-aldehyde (8) was coupled with
phosphonate ester to afford the 2,4,6-octatrienoic ester
Binding activity data showed that (E,E,E)-7-[1-(1-
methylethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-3-meth-
ylocta-2,4,6-trienoic acid (10) exhibits a potent and
selective affinity for RXR-R, with affinity for RARs
weaker than that of (E,E,E)-7-(5,6,7,8-tetrahydro-5,5,8,8-
tetramethyl-2-naphthalenyl)-3-methylocta-2,4,6-trieno-
(9), which was hydrolyzed to give the 2,4,6-octatrienoic
acid (10).
Initial experiments were aimed at construction of the
9
-cis form of compound 10. After the Horner-Emmons
3
8
reaction, the (Z)-butenoic acid ester 6 was separated by
flash column chromatography with silica gel. The (Z)-
ester 6 was reduced with DIBAL-H at -70 °C to obtain
the (Z)-alcohol 7. All attempts at oxidation of the (Z)-
butenol 7 using manganese(IV) oxide, Dess-Martin
reagent and Swern oxidation reagent resulted in isomer-
ic acid (Ro 13-6307 ). Although Ro 13-6307 has no
affinity for RXR-R, compound 10, which has a N atom
in the hydrophobic part, binds strongly to RXR-R and
is a correspondingly potent activator of RXRs. Addition
of fluorine at the 6-position of the triene moiety of 10
afforded compounds 14a -14c, which bind with even

Novel Retinoid X Receptor Agonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17 3247
Sch em e 1a
a
4
Reagents: (a) i-PrI, K2CO3, DMF; (b) POCl3, DMF; (c) R MgBr, ether; (d) MnO2, acetone; (e) (EtO)2P(O)CH2COOEt, NaH, DMF; (f)
DIBAL-H, THF; (g) (EtO)2P(O)CH2C(Me)dCHCOOMe, NaH, DMF; (h) NaOH aqueous EtOH: (i) (EtO)2P(O)CHFCOOEt, NaH, DMF
and separation.
Ta ble 1. Chemical Shifts and 1H-19F Coupling Constants of
C-3 (11a and 12a ) and C-7 (13a ) Methyl Proton
Ta ble 2. 1H NMR Signals and 1H-19F Coupling Constants for
the 6-Fluoro-Substituted Compounds (14a -d )
compd
R
R′
δ
4J 1H-19
F
(
(
(
(
(
(
E)-11a
Z)-11a
E)-12a
Z)-12a
6E)-13a
6Z)-13a
-COOEt
-F
-F
2.12
2.43
2.25
2.42
2.12
2.13
4.8
3.2
3.6
3.2
3.6
2.8
1H NMR chemical shifts, δ
-COOEt
-F
-CHO
-F
-CHO
-F
coupling constants, Hz
C-2 C-3 C-4 C-5 C-8
4J H-F
3J H-F
compd
R
H
CH
3
H
H
CH
2
J
4,5
a
-A
a
14a
H
5.86 2.21 6.52 6.71 2.12 15.6
3.2
2.8
2.8
2.8
26.4
25.6
26.0
26.0
-F
-A
1
1
1
4b Me 5.85 2.19 6.51 6.63 2.55 15.6
4c Et 5.85 2.19 6.51 6.64 2.55 16.0
4d n-Pr 5.85 2.19 6.51 6.64 2.55 16.0
a
A ) (E,E)-CHdCH-C(CH3)dCH-COOMe.
higher affinity to RXR-R and elicit potent and selective
activation of the RXRs. Although the “stable 9-cis form”
analogues 14a -c have a binding affinity for RXR-R
higher than that of the parent compound 10 (Table 3),
introduction of an n-butyl substituent at the 7-position
of the 2,4,6-heptatrienoic moiety (14d ) reduced the
affinity for RXR-R approximately 10-fold.
tors of RXRs. The n-propyl analogue (14c) had relative
EC30 values for activation of the RXRs that were
somewhat higher than those of the parent 7-methyl
analogue (14a ), whereas the 7-ethyl analogue (14b) had
relative EC30 values lower than that of 14a . Although
14a was capable of activating the RARs (especially RAR-
â, γ), analysis of the relative EC30 and efficacy (%) of
transactivation suggested that 14b and 14c function
The 7-alkyl-6-“cis”-3-methylhepta-2,4,6-trienoic acid
derivatives (compounds 14a -d ) were also potent activa-

3
248 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17
Hibi et al.
Ta ble 3. Competitive Binding and Transactivation Data for Compound 10 and (E,E,E)-7-(1,2,3,4-Tetrahydroquinolin-6-yl)-7-alkyl-6-
fluoro-3-methylhepta-2,4,6-trienoic Acid Derivatives (14)
a
Specific binding affinity was defined as the total binding minus the nonspecific binding, and the 50% inhibitory dose (IC50) values
were obtained from logarithmic plots. In some cases, Scatchard plot analysis was performed. The selectivity of test compounds for each
receptor is indicated as relative IC50, where the IC50 value for each receptor was divided by that of the natural ligand (ATRA or 9-cis-RA).
b
EC30 values were determined from full dose-response curves ranging from 0.1 nM to 3 µM. Retinoid activity is expressed in terms of
relative EC50, which is the concentration of retinoid required to produce 30% of the maximal observed response, normalized relative to
that of ATRA or 9-cis-RA. Efficacy was calculated as percent maximal induction normalized to 9-cis-RA for the RXRs and to ATRA for
c
d
e
the RARs. Not detected at 500 nM. Test compounds showing less than 30% of the maximal activity of ATRA or 9-cis-RA at 3 µM were
considered inactive. f Binding affinity (IC50). Transactivation (EC30).
g
only as RXR agonists. Introduction of an n-butyl
substituent at the 7-position of the triene moiety (14d )
significantly decreased the potency at RXRs. These
findings can be more clearly depicted by a graphical
representation of the cotransfection data (Figure 1).
Thus, in this series, the nature of the 7-alkyl group
critically determines the agonist activity of these ret-
inoid ligands.
Compound 14b, which has an ethyl substituent at the
7
-position and fluorine at the 6-position of the triene
moiety, is one of the most potent and selective RXRs
agonists reported to date. It causes transactivation of
RXRs approximately 10-fold more potent than Targretin
F igu r e 1. Transactivation dose-response curves for RXR-R
of 9-cis-RA, 14a -d , and LGD 1069.
(
LGD 1069), which is under development for the treat-
2
1
22
ment of cancer and diabetes.
It is evident that the stable 9-cis conformation plays
a critical role in orienting the triene moiety with respect
to the tetrahydroquinoline nucleus. Compound 14b
(ER-35794) showed good absorption into the systemic
circulation after oral administration in preclinical stud-
ies (data not shown). In view of its specific agonist

Novel Retinoid X Receptor Agonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17 3249
activities for RXRs, 14b could be a candidate for clinical
application.
After the addition was completed, the mixture was stirred at
room temperature for 30 min, and then a solution of 1-[1-(1-
methylethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-ethanone (5a) (5.5
g, 25.3 mmol) in N,N-dimethylformamide (10 mL) was added
dropwise. The reaction mixture was stirred for 48 h under
heating at 60 °C and then poured onto 100 mL of ice-water.
The whole mixture was extracted with ethyl acetate twice. The
organic layer was separated, dried, and evaporated. The crude
residue was purified by flash column chromatography on silica
gel (solvent, n-hexane-ethyl acetate ) 96:4) to afford 6 (4.0
Exp er im en ta l Section
Ch em istr y. Reagents and solvents were purchased from
the usual commercial sources. Silica gel (Kieselgel 60, Merck)
was used for column chromatography and silica gel (Kieselgel
6
0 F254, Merck) for analytical thin-layer chromatography
(TLC). Compounds were detected on TLC plates by exposure
to UV light (254 nm). Melting points were measured on a
Yanagimoto micro melting point apparatus without correction.
1
g, 13.9 mmol, 55%) as a colorless oil: H NMR (400 MHz,
CDCl
3
) δ 1.20 (d, J ) 6.5 Hz, 6H), 1.31 (t, J ) 6.5 Hz, 3H),
1
H NMR spectra were recorded on a Varian Unity 400
1
.90 (tt, J ) 6.0, 6.0 Hz, 2H), 2.55 (d, J ) 1.0 Hz, 3H), 2.74 (t,
spectrometer, and chemical shifts are expressed in ppm
downfield from tetramethylsilane (TMS) as an internal refer-
ence. Mass spectra (MS) were obtained on a J EOL J MS-
HX100 mass spectrometer. All organic extracts were dried
J ) 6.0 Hz, 2H), 3.20 (t, J ) 6.0 Hz, 2H), 4.13 (hept, J ) 6.5
Hz, 1H), 4.19 (q, J ) 6.5 Hz, 2H), 6.09 (q, J ) 1.0 Hz, 1H),
6
.64 (d, J ) 9.0 Hz, 1H), 7.18 (d, J ) 2.0 Hz, 1H), 7.29 (dd, J
2.0, 9.0 Hz, 1H).
E)-3-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r oqu in olin -6-
)
over anhydrous MgSO
rotary evaporator under reduced pressure.
-(1-Met h ylet h yl)-1,2,3,4-t et r a h yd r oq u in olin e-6-ca r -
4
, and the solvent was removed with a
(
yl]-2-bu ten ol (7). To a solution of ethyl (E)-3-[1-(1-methyl-
ethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-2-butenoate (6) (1.0 g,
1
ba ld eh yd e (3). To a flask containing 29.2 g (0.4 mol) of N,N-
dimethylformamide cooled to 10 °C and protected from mois-
ture was added 18.6 g (0.12 mol) of phosphorus oxychloride.
3
.5 mmol) in THF (20 mL) was added dropwise a 1.5 M
solution of diisobutylaluminum hydride in n-hexane (7.0 mL,
0.5 mmol) at -70 °C. The reaction mixture was stirred for 3
1
1
-(1-Methylethyl)-1,2,3,4-tetrahydroquinoline (2) (17.5 g, 0.10
h at the same temperature, quenched with a saturated
aqueous solution of ammonium chloride, stirred for 2 h, and
then extracted with ethyl acetate. The organic layer was
washed with brine, dried, and evaporated to afford 7 (650 mg,
2.6 mmol, 74%) as a colorless oil which was used in the next
mol) in N,N-dimethylformamide (3 mL) was then added slowly
with stirring at such a rate to keep the temperature at 20-35
°
C. The mixture was kept at 35 °C for 30 min, and then it
was poured onto crushed ice. The whole was neutralized with
a saturated aqueous solution of sodium hydrogen carbonate
and extracted with ethyl acetate twice. The organic layer was
washed with brine, dried, and evaporated. The crude residue
was purified by flash column chromatography on silica gel
step without further purification: 1H NMR (400 MHz, CDCl
)
3
δ 1.18 (d, J ) 6.5 Hz, 6H), 1.90 (tt, J ) 6.0, 6.0 Hz, 2H), 2.04
(s, 3H), 2.74 (t, J ) 6.0 Hz, 2H), 3.17 (t, J ) 6.0 Hz, 2H), 4.11
(hept, J ) 6.5 Hz, 1H), 4.18 (br. d, J ) 5.0 Hz, 1H), 4.33 (d,
J ) 6.5 Hz, 2H), 5.89 (t, J ) 6.5 Hz, 1H), 6.64 (d, J ) 8.5 Hz,
1H), 7.06 (d, J ) 2.0 Hz, 1H), 7.14 (dd, J ) 2.0, 8.5 Hz, 1H).
(
0
solvent, n-hexane-ethyl acetate ) 1:9) to afford 3 (11.4 g,
1
.056 mol, 56%) as a red-brown oil: H NMR (400 MHz, CDCl
3
)
δ 1.23 (d, J ) 6.5 Hz, 6H), 1.90 (tt, J ) 6.0, 6.0 Hz, 2H), 2.75
(
6
7
t, J ) 6.0 Hz, 2H), 3.27 (t, J ) 6.0 Hz, 2H), 4.20 (hept, J )
(
E)-3-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r oqu in olin -6-
yl]-2-bu ten a l (8). To a solution of (E)-3-[1-(1-methylethyl)-
,2,3,4-tetrahydroquinolin-6-yl]-2-butenol (7) (650 mg, 2.6
mmol) in acetone (10 mL) was added manganese(IV) oxide
activated, <5 µm) (3.5 g) at room temperature. The mixture
was stirred for 12 h at the same temperature, and manganese-
IV) oxide was filtered out with Celite. The organic solution
.5 Hz, 1H), 6.69 (d, J ) 9.0 Hz, 1H), 7.45 (d, J ) 2.0 Hz, 1H),
.55 (dd, J ) 2.0, 9.0 Hz, 1H), 9.63 (s, 1H).
1
1
-[1-(1-Met h ylet h yl)-1,2,3,4-t et r a h yd r oq u in olin -6-yl]-
eth a n ol (4a ). To a 3.0 M solution of methylmagnesium
bromide (4.9 mL, 15 mmol) in diethyl ether (15 mL) was added
(
1
-(1-methylethyl)-1,2,3,4-tetrahydroquinolin-6-carbaldehyde (3)
(
(2.0 g, 9.8 mmol) in diethyl ether (10 mL) over a period of 10
was evaporated. The crude residue was purified by flash
column chromatography on silica gel (solvent, n-hexane-ethyl
acetate ) 1:9) to afford 8 (400 mg, 1.6 mmol, 62%) as a light
min while the ether refluxed as a result of the heat reaction.
After the mixture had been stirred at room temperature for 1
h, the mixture was quenched with a saturated aqueous
solution of ammonium chloride and extracted with ethyl
acetate. The organic layer was washed with brine, dried, and
evaporated to afford 4a (2.1 g, 9.6 mmol, 98%) as a red-brown
yellow oil: 1H NMR (400 MHz, CDCl
6
3
) δ 1.22 (d, J ) 6.5 Hz,
H), 1.91 (tt, J ) 6.0, 6.0 Hz, 2H), 2.50 (s, 3H), 2.75 (t, J ) 6.0
Hz, 2H), 3.23 (t, J ) 6.0 Hz, 2H), 4.16 (hept, J ) 6.5 Hz, 1H),
6
2
.41 (d, J ) 8.0 Hz, 1H), 6.67 (d, J ) 9.0 Hz, 1H), 7.26 (d, J )
.0 Hz, 1H), 7.38 (dd, J ) 2.0, 9.0 Hz, 1H), 10.10 (d, J ) 8.0
oil which was used in the next step without further purifica-
1
tion: H NMR (400 MHz, CDCl
1
3
) δ 1.19 (d, J ) 6.5 Hz, 6H),
Hz, 1H).
.48 (d, J ) 6.5 Hz, 3H), 1.91 (tt, J ) 6.0, 6.0 Hz, 2H), 2.75 (t,
Met h yl (E,E,E)-7-[1-(1-Met h ylet h yl)-1,2,3,4-t et r a h yd -
J ) 6.0 Hz, 2H), 3.17 (t, J ) 6.0 Hz, 2H), 4.11 (hept, J ) 6.5
r oqu in olin -6-yl]-3-m eth ylocta -2,4,6-tr ien oa te (9). To a
suspension of 60% sodium hydride (98 mg, 2.46 mmol) in N,N-
dimethylformamide (10 mL) was added dropwise a solution
of methyl 3-methyl-4-diethylphosphonocrotonate (560 mg, 2.14
mmol) in N,N-dimethylformamide (10 mL) at 0 °C. After the
addition was completed, the mixture was stirred at room
temperature for 30 min, and then a solution of (E)-3-[1-(1-
methylethyl)-1,2,3,4-tetrahydroquinolin-6-yl]-2-butenal (8) (400
mg, 1.64 mmol) in N,N-dimethylformamide (10 mL) was added
dropwise. The reaction mixture was stirred for 1 h and then
poured onto 100 mL of ice-water. The whole mixture was
extracted with ethyl acetate twice. The organic layer was
separated, dried, and evaporated. The crude residue was
purified by flash column chromatography on silica gel (solvent,
n-hexane-ethyl acetate ) 85:15) to afford 9 (330 mg, 0.97
Hz, 1H), 4.76 (q, J ) 6.0 Hz, 1H), 6.67 (d, J ) 9.0 Hz, 1H),
6
.99 (d, J ) 2.0 Hz, 1H), 7.07 (dd, J ) 2.0, 9.0 Hz, 1H).
1
-[1-(1-Met h ylet h yl)-1,2,3,4-t et r a h yd r oq u in olin -6-yl]-
eth a n on e (5a ). To a solution of 1-[1-(1-methylethyl)-1,2,3,4-
tetrahydroquinolin-6-yl]-ethanol (4a ) (2.1 g, 9.6 mmol) in
acetone (10 mL) was added manganese(IV) oxide (activated,
<
5 µm) (10 g) at room temperature. The mixture was stirred
for 12 h at the same temperature, and manganese(IV) oxide
was filtered out with Celite. The organic solution was
evaporated. The crude residue was purified by flash column
chromatography on silica gel (solvent, n-hexane-ethyl acetate
)
1:9) to afford 5a (1.3 g, 6.0 mmol, 63%) as a light yellow oil:
1
H NMR (400 MHz, CDCl
3
) δ 1.22 (d, J ) 6.5 Hz, 6H), 1.89
(
3
tt, J ) 6.0, 6.0 Hz, 2H), 2.48 (s, 3H), 2.75 (t, J ) 6.0 Hz, 2H),
.24 (t, J ) 6.0 Hz, 2H), 4.19 (hept, J ) 6.5 Hz, 1H), 6.63 (d,
mmol, 59%) as a red-brown oil: 1H NMR (400 MHz, CDCl
) δ
J ) 9.0 Hz, 1H), 7.59 (d, J ) 2.0 Hz, 1H), 7.69 (dd, J ) 2.0,
3
9
.0 Hz, 1H).
1.20 (d, J ) 6.8 Hz, 6H), 1.91 (tt, J ) 6.0, 6.0 Hz, 2H), 2.20 (s,
3H), 2.38 (d, J ) 0.8 Hz, 3H), 2.75 (t, J ) 6.0 Hz, 2H), 3.19 (t,
J ) 6.0 Hz, 2H), 3.72 (s, 3H), 4.15 (hept, J ) 6.8 Hz, 1H), 5.77
(s, 1H), 6.32 (d, J ) 15.2 Hz, 1H), 6.53 (d, J ) 11.2 Hz, 1H),
6.65 (d, J ) 8.8 Hz, 1H), 7.06 (dd, J ) 11.2, 15.2 Hz, 1H), 7.15
(d, J ) 2.4 Hz, 1H), 7.25 (dd, J ) 2.4, 8.8 Hz, 1H).
Eth yl (E)-3-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r oqu in o-
lin -6-yl]-2-bu ten oa te (6). To a suspension of 60% sodium
hydride (2.0 g, 51 mmol) in N,N-dimethylformamide (10 mL)
was added dropwise a solution of triethyl phosphonoacetate
(11.3 g, 51 mmol) in N,N-dimethylformamide (10 mL) at 0 °C.

3
6
250 J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17
Hibi et al.
(
E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr ah ydr oqu in olin -
0.8H
2
O) C, N; H: calcd, 7.77; found, 7.12. HRMS Calcd for
-yl]-3-m eth ylocta -2,4,6-tr ien oic Acid (10). A solution of
C
21
H
26FNO
2
: 343.1947. Found: 343.1955.
methyl (E,E,E)-7-[1-(1-methylethyl)-1,2,3,4-tetrahydroquino-
lin-6-yl]-3-methylocta-2,4,6-trienoate (9) (330 mg, 0.97 mmol)
in ethanol (10 mL) was treated with 5 N sodium hydroxide
solution (1.0 mL). The mixture was heated under a nitrogen
atmosphere at 60 °C for 1 h followed by the addition of 3 g of
ice. The pH thereof was adjusted to 5 with 6 N hydrochloric
acid. The precipitate was collected by filtration and washed
with water. This product was recrystallized from ethanol to
(
E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr ah ydr oqu in olin -
6
-yl]-6-flu or o-3-m eth yln on a-2,4,6-tr ien oic Acid (14b). Com-
pound 14b was synthesized from 13b by following the repre-
sentative procedure described for 10. An orange solid of 14b
1
was obtained in 26% yield: mp 161-162 °C (EtOH); H NMR
(
3
400 MHz, CDCl ) δ 1.01 (t, J ) 7.2 Hz, 3H), 1.21 (d, J ) 6.8
Hz, 6H), 1.88-1.95 (m, 2H), 2.19 (s, 3H), 2.55 (dq, J ) 2.8, 7.6
Hz, 2H), 2.73 (t, J ) 6.0 Hz, 2H), 3.20 (t, J ) 6.0 Hz, 2H), 4.13
afford 10 (100 mg, 0.31 mmol, 32%) as an orange solid: mp
(
6
hept, J ) 6.4 Hz, 1H), 5.85 (s, 1H), 6.51 (d, J ) 15.2 Hz, 1H),
.63 (dd, J ) 16.0, 25.6 Hz, 1H), 6.65 (d, J ) 8.8 Hz, 1H), 6.83
d, J ) 2.4 Hz, 1H), 6.91 (dd, J ) 2.4, 8.8 Hz, 1H). Anal.
‚0.1H O) C, H, N. HRMS Calcd for C22
57.2104. Found: 357.2112.
E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr ah ydr oqu in olin -
-yl]-6-flu or o-3-m eth yldeca-2,4,6-tr ien oic Acid (14c). Com-
1
1
)
(
(
6
72-173 °C (EtOH); H NMR (400 MHz, CDCl
3
) δ 1.19 (d, J
6.5 Hz, 6H), 1.91 (tt, J ) 6.0, 6.0 Hz, 2H), 2.21 (s, 3H), 2.39
s, 3H), 2.75 (t, J ) 6.0 Hz, 2H), 3.19 (t, J ) 6.0 Hz, 2H), 4.13
hept, J ) 6.5 Hz, 1H), 5.79 (s, 1H), 6.35 (d, J ) 15.0 Hz, 1H),
(
(
C
22
H
28FNO
2
2
2
H28FNO :
3
.55 (d, J ) 11.0 Hz, 1H), 6.66 (d, J ) 9.0 Hz, 1H), 7.10 (dd,
J ) 15.0, 11.0 Hz, 1H), 7.16 (d, J ) 2.0 Hz, 1H), 7.26 (dd, J )
.0, 2.0 Hz, 1H). Anal. (C21 ‚H O) C, N; H: calcd, 8.51;
found, 7.95. HRMS Calcd for C21 : 325.2042. Found:
25.2040.
Eth yl (E)-3-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r oqu in o-
lin -6-yl]-2-flu or o-2-bu ten oa te (11a ). To a suspension of
0% sodium hydride (450 mg, 11.3 mmol) in N,N-dimethyl-
formamide (10 mL) was added dropwise a solution of triethyl
-fluoro-2-phosphonoacetate (3.3 g, 13.6 mmol) in N,N-di-
(
6
9
H
27NO
2
2
pound 14c was synthesized from 13c by following the repre-
sentative procedure described for 10. An orange solid of 14c
was obtained in 96% yield: mp 120-121 °C (EtOH-water);
H
27NO
2
3
1
H NMR (400 MHz, CDCl ) δ 0.89 (t, J ) 7.6 Hz, 3H), 1.21 (d,
3
J ) 6.8 Hz, 6H), 1.39 (tq, J ) 7.6, 7.6 Hz, 2H), 1.88-1.95 (m,
2H), 2.19 (s, 3H), 2.51 (dt, J ) 2.8, 7.6 Hz, 2H), 2.73 (t, J )
6.0 Hz, 2H), 3.20 (t, J ) 6.0 Hz, 2H), 4.12 (hept, J ) 6.4 Hz,
1H), 5.86 (s, 1H), 6.51 (d, J ) 16.0 Hz, 1H), 6.64 (dd, J ) 16.0,
26.0 Hz, 1H), 6.64 (d, J ) 9.2 Hz, 1H), 6.82 (d, J ) 2.4 Hz,
1H), 6.91 (dd, J ) 2.4, 8.8 Hz, 1H). Anal. (C H FNO ‚0.4H O)
6
2
methylformamide (10 mL) at 0 °C. After the addition was
completed, the mixture was stirred at 0 °C for 1 h, and then
a solution of 1-[1-(1-methylethyl)-1,2,3,4-tetrahydroquinolin-
2
3
30
2
2
C, H, N. HRMS calcd for C H FNO : 371.2260. Found:
2
3
30
2
6
-yl]-ethanone (5a ) (2.0 g, 9.2 mmol) in N,N-dimethylform-
371.2256.
E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr ah ydr oqu in olin -
-yl]-6-flu or o-3-m eth ylu n d eca -2,4,6-tr ien oic Acid (14d ).
amide (10 mL) was added dropwise. The reaction mixture was
stirred for 1 h at 0 °C then poured onto ice-water. The whole
mixture was extracted with ethyl acetate twice. The organic
layer was separated, dried, and evaporated. The crude residue
was purified by flash column chromatography on silica gel
(
6
Compound 14d was synthesized from 13d by following the
representative procedure described for 10. An orange solid of
4d was obtained in 65% yield: mp 82-83 °C (EtOH-water);
H NMR (400 MHz, CDCl
1
(
solvent, n-hexane-ethyl acetate ) 90:10) to afford 11a (2.3
1
3
) δ 0.87 (t, J ) 6.8 Hz, 3H), 1.21 (d,
1
g, 7.5 mmol, 66%) as a colorless oil: H NMR (400 MHz, CDCl
δ 1.14 (t, J ) 7.2 Hz, 3H), 1.18 (d, J ) 6.8 Hz, 6H), 1.89 (tt, J
6.0, 6.0 Hz, 2H), 2.12 (d, J ) 4.8 Hz, 3H), 2.71 (t, J ) 6.0
Hz, 2H), 3.17 (t, J ) 6.0 Hz, 2H), 4.12 (hept, J ) 6.8 Hz, 1H),
3
)
J ) 6.4 Hz, 6H), 1.25-1.40 (m, 4H), 1.92 (tt, J ) 6.0, 6.0 Hz,
2
3
1
1
H), 2.19 (s, 3H), 2.45-2.60 (m, 2H), 2.73 (t, J ) 6.0 Hz, 2H),
.20 (t, J ) 6.0 Hz, 2H), 4.12 (hept, J ) 6.4 Hz, 1H), 5.85 (s,
H), 6.51 (d, J ) 15.2 Hz, 1H), 6.63 (dd, J ) 16.0, 26.0 Hz,
H), 6.64 (d, J ) 8.8 Hz, 1H), 6.82 (d, J ) 2.4 Hz, 1H), 6.91
)
4
2
.12 (q, J ) 7.2 Hz, 2H), 6.61 (d, J ) 8.4 Hz, 1H), 6.81 (d, J )
.0 Hz, 1H), 6.92 (dd, J ) 2.4, 8.8 Hz, 1H).
(
dd, J ) 2.4, 8.8 Hz, 1H). Anal. (C24
H: calcd, 8.59; found, 7.50. HRMS Calcd for C H32FNO2:
H
32FNO
2
‚1.8H
2
O) C, N;
Eth yl (E)-3-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r oqu in o-
2
4
lin -6-yl]-2-flu or o-2-bu ten a l (12a ). Compound 12a was syn-
thesized from 11a by following the representative procedure
385.2416. Found: 385.2415.
Biology. P la sm id Con str u ction . Full-length human
RAR-R, â, and γ and RXR-R, â, and γ cDNAs were cloned by
polymerase chain reaction (PCR) from QUICK-clone cDNA
described for 4a and 5a . A colorless oil of 12a was obtained
1
in 39% yield: H NMR (400 MHz, CDCl
3
) δ 1.21 (d, J ) 6.8
Hz, 6H), 1.91 (tt, J ) 6.0, 6.0 Hz, 2H), 2.25 (d, J ) 3.6 Hz,
H), 2.73 (t, J ) 6.0 Hz, 2H), 3.22 (t, J ) 6.0 Hz, 2H), 4.12
hept, J ) 6.8 Hz, 1H), 6.66 (d, J ) 8.8 Hz, 1H), 6.92 (d, J )
.4 Hz, 1H), 7.02 (dd, J ) 2.4, 8.4 Hz, 1H), 9.35 (d, J ) 19.6
Hz, 1H).
Meth yl (E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr a h yd r o-
(
Clontech, Palo Alto, CA) derived from liver or placenta, and
3
(
2
the correctness of the sequences was confirmed. Each cDNA
was inserted into the PstI/KpnI site of expression vector
pcDLSRR-296. The reporter plasmids, CRBP I-PLAP and
CRBP II-PLAP, were constructed as follows. The response
element CRBPI (DR2) or CRBPII (DR1) was synthesized and
inserted into the 5′-SpeI and 3′-XbaI site upstream of the
thymidine kinase (TK) promoter in pTK-PLAP.40
39
1
3
qu in olin -6-yl]-6-flu or o-3-m eth ylocta-2,4,6-tr ien oate (13a).
Compound 13a was synthesized from 12a by following the
representative procedure described for 9. A brown oil of 13a
Bin d in g Assa y. Unlabeled ATRA was purchased from
1
was obtained in 97% yield: H NMR (400 MHz, CDCl
3
) δ 1.21
3
Sigma (St. Louis, MO). [ H]-ATRA was purchased from
(d, J ) 6.8 Hz, 6H), 1.92 (tt, J ) 6.0, 6.0 Hz, 2H), 2.12 (d, J )
3
DuPont/NEN. Unlabeled 9-cis-RA or [ H]-9-cis-RA was syn-
3
3
1
.6 Hz, 3H), 2.21 (d, J ) 0.8 Hz, 3H), 2.74 (t, J ) 6.0 Hz, 2H),
.20 (t, J ) 6.0 Hz, 2H), 3.70 (s, 3H), 4.13 (hept, J ) 6.8 Hz,
H), 5.84 (s, 1H), 6.50 (d, J ) 15.6 Hz, 1H), 6.66 (d, J ) 8.4
3
thesized from ATRA or [ H]-ATRA by the method of Heyman
15
et al. The pcDLSRR296 human RAR-R, â, and γ or RXR-R
and pSV2-DHFR plasmid were cotransfected into BHK cells
by the calcium phosphate method. For the selection of a stable
transformant, the transfected cells were maintained in the
medium containing 250 nM methotrexate (MTX). We selected
several clones which were resistant to MTX, and the receptor
sequence was confirmed by PCR. The nuclear extracts of these
stable transformants were used for the binding assay. Nuclear
Hz, 1H), 6.68 (dd, J ) 15.6, 26.4 Hz, 1H), 6.87 (d, J ) 2.4 Hz,
1
H), 6.95 (dd, J ) 2.4, 8.4 Hz, 1H).
E,E,E)-7-[1-(1-Meth yleth yl)-1,2,3,4-tetr ah ydr oqu in olin -
-yl]-6-flu or o-3-m eth ylocta-2,4,6-tr ien oic Acid (14a). Com-
(
6
pound 14a was synthesized from 13a by following the repre-
sentative procedure described for 10. An orange solid of 14a
1
27
was obtained in 47% yield: mp 138-139 °C (EtOH); H NMR
extracts were prepared by the method of Nervi et al. A 180-
(
400 MHz, CDCl
.0 Hz, 2H), 2.12 (d, J ) 3.2 Hz, 3H), 2.21 (s, 3H), 2.74 (t, J )
.0 Hz, 2H), 3.20 (t, J ) 6.0 Hz, 2H), 4.13 (hept, J ) 6.4 Hz,
H), 5.86 (s, 1H), 6.52 (d, J ) 15.6 Hz, 1H), 6.66 (d, J ) 8.4
3
) δ 1.21 (d, J ) 6.4 Hz, 6H), 1.92 (tt, J ) 6.0,
µL aliquot of nuclear extract was incubated with 10 µL of 10
3
3
6
6
1
nM [ H]-ATRA or 15 nM [ H]-9-cis-RA and 10 µL of various
concentrations of unlabeled compounds in a 96-well polypro-
pylene plate. The plate was incubated for 16 h at 4 °C, and
then 50 µL/well of a charcoal/dextran suspension (3% Norit
A/0.3% dextran in 10 mM Tris-HCl pH 7.4, 0.02% sodium
Hz, 1H), 6.71 (dd, J ) 15.6, 26.4 Hz, 1H), 6.87 (d, J ) 2.0 Hz,
2
H), 6.95 (dd, J ) 2.4, 8.8 Hz, 1H). Anal. (C21H26FNO ‚
1

Novel Retinoid X Receptor Agonists
J ournal of Medicinal Chemistry, 1998, Vol. 41, No. 17 3251
azide) was added for 10 min at 4 °C. The plate was centrifuged
for 5 min, and the supernatants were subjected to liquid
scintillation counting. Binding in the presence of a 1000-fold
excess of unlabeled ligand was defined as nonspecific binding.
Specific binding was defined as the total binding minus the
nonspecific binding, and the 50% inhibitory dose (IC50) values
were obtained from logarithmic plots. The selectivity of
(10) Mangelsdorf, D. J .; Evans, R. M. The RXR Heterodimers and
Orphan Receptors. [Review] Cell 1995, 83, 841-850.
(
11) Predki, P. F.; Zamble, D.; Sarkar, B.; Giguere, V. Ordered
Binding of Retinoic Acid and Retinoid X Receptors to asymmetric
Response Elements Involves Determinants Adjacent to the DNA
Binding Domain. Mol. Endocrinol. 1994, 8, 31-39.
(12) Heyman, R. A.; Mangelsdorf, D. J .; Dyck, J . A.; Stein, R. B.;
Eichele, G.; Evans, R. M.; Thaller, C. 9-cis Retinoic Acid is a
High Affinity Ligand for the Retinoid X Receptor. Cell 1992, 68,
compounds for each receptor is indicated as relative IC50
,
3
97-406.
obtained by dividing the IC50 value for each receptor of the
compound by that of the natural ligand (ATRA or 9-cis-RA).
Tr a n sa ctiva tion Assa y. COS-1 cells at 80% confluence
in a 60-mm dish were incubated with 6 µg of receptor
expression plasmid, 6 µg of reporter plasmid, and 40 µL of
Lipofectamine (GIBCO-BRL, Gaithersburg, MD) per dish in
OPTI-MEM (GIBCO-BRL). After the cells had incubated for
(
13) Lehmann, J . M.; J ong, L.; Fanjul, A.; Cameron, J . F.; Lu, X. P.;
Haefner, P.; Dawson, M. I.; Pfahl, M. Retinoids Selective for
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1
944-1946.
(
14) J ong, L.; Lehmann, J . M.; Hobbs, P. D.; Harlev, E.; Huffmann,
J . C.; Pfahl, M.; Dawson, M. I. Conformational Effects on
Retinoid Receptor Selectivity. 1. Effect of 9-Double Bond Geom-
etry on Retinoid X Receptor Activity. J . Med. Chem. 1993, 36,
2605-2613.
4
h, the medium was replaced with D-MEM (GIBCO-BRL)
supplemented with 10% FBS, and incubation was continued
for 20 h. The cells were then suspended in D-MEM supple-
(15) Boehm, M. F.; Zhang, L.; Badea, B.; White, S. K.; Mais, D. E.;
Berger, E.; Suto, C. M.; Goldman, M. E.; Heyman, R. A.
Synthesis and Structure-Activity Relationships of Novel Ret-
inoid X Receptor Selective Retinoids. J . Med. Chem. 1994, 37,
4
mented with 10% FBS and seeded at 3 × 10 per well in 96-
well plates. After the cells had incubated for 6 h, compounds
at various concentrations were added to duplicate wells. The
cells were incubated for a further 48 h, and then the super-
2
930-2941.
(16) Dawson, M. I.; J ong, L.; Hobbs, P. D.; Cameron, J . F.; Chao, W.;
Pfahl, M.; Lee, M.-O.; Shroot, B.; Pfahl, M. Conformational
Effects on Retinoid Receptor Selectivity 2. Effects of Retinoid
Bridging Group on Retinoid X Receptor Activity and Selectivity.
J . Med. Chem. 1995, 38, 3368-3383.
4
0
natants were assayed for PLAP activity.
nonspecific activity, the samples were preheated at 65 °C for
0 min. Aliquots of 15 µL were mixed with 60 µL of assay
buffer (0.28 M Na CO -NaHCO , pH 10.0, containing 8 mM
MgSO ) and reacted with 75 µL of substrate (Lumistain,
To inactivate
2
(
17) Boehm, M. F.; Zhang, L.; Zhi, L.; McClurg, M. R.; Berger, E.;
Wagoner, M.; Mais, D. E.; Suto, C. M.; Davies, P. J . A.; Heyman,
R. A.; Nadzan, A. M. Design and Synthesis of Potent Retinoid X
Receptor Selective Ligands that Induce Apotosis in Leukemia
Cells. J . Med. Chem. 1995, 38, 3146-3155.
18) Vuligonda, V.; Lin, Y.; Chandraratna, R. A. S. Synthesis of
Highly Potent RXR-Specific Retinoids: The Use of a Cyclopropyl
Group as a Double Bond Isostere Bioorg. Med. Chem. Lett. 1996,
6, 213-218.
2
3
3
4
Sumitomo, Osaka, J apan). After the reaction mixture had
incubated for 30 min at 37 °C and 30 min at room temperature,
steady-state chemiluminescence was measured with a micro-
plate luminometer (LB96P, EG&G Bertold, Bad Wildbad,
Germany). A 100% transactivation was defined as the value
at 3 µM natural ligand (ATRA or 9-cis-RA), and the 30%
efficacy dose (EC30) values of compounds were obtained from
logarithmic plots. The selectivity of compounds for each
receptor is indicated as relative EC30, obtained by dividing the
EC30 value for each receptor of the compound by that of the
natural ligand (ATRA or 9-cis-RA).
(
(19) Beard, R. L.; Colon, D. F.; Song, T. K.; Davies, P. J . A.; Kochhar,
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20) Farmer, L. J .; J eong, S.; Kallel, E. A.; Canan Koch S. S.; Croston,
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(
Ack n ow led gm en t. We thank Dr. Yutaka Takebe,
DNAX Research Institute of Molecular and Cellular
Biology, for providing the expression vector pcDLSRR-
1
997, 15, 790-795.
2
96, Dr. Shigeaki Kato, Institute of Molecular and
(
22) Mukherjee, R.; Davies, P. J . A.; Crombie, D. L.; Bischoff, E. D.;
Cesario, R. M.; J ow, L.; Hamann, L. G.; Boehm, M. F.; Mondon,
C. E.; Nadzan, A. M.; Paterniti, J . R., J r.; Heyman, R. A.
Sensitization of Diabetic and Obese Mice to Insulin by Retinoid
X Receptor Agonists. Nature 1997, 386, 407-410.
Cellular Biosciences, University of Tokyo, for providing
the COS-1 cells, and Dr. Isao Tanaka for providing the
TK promoter in pTK-PLAP.
(
23) Bischoff, E. D.; Gottardis, M. M.; Moon, T. E.; Heyman, R. A.;
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selective Ligand LGD 1069 (TARGRETIN) Causes Complete
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d ) (4 pages). Ordering information is given on any current
masthead page.
4
84.
(
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Interaction of Glucocorticoid Analogues with the Human Glu-
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(
(
(
(
(
(
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