Chronobiotic activity of N-[2-(2,7-dimethoxyfluoren-9-yl)ethyl]- propanamide. Synthesis and melatonergic pharmacology of fluoren-9-ylethyl amides

Article abstract of DOI:10.1016/j.bmc.2004.07.002

Compound 2b demonstrated full agonism at both human MT₁ and MT₂ receptors and demonstrated chronobiotic activity in both acute and chronic rat models, producing an acute phase advance of 32 min at 1 mg/kg and chronically entraining free-running rats with a mean effective dose of 0.23 mg/kg. This compound was significantly less efficacious than melatonin in constricting human coronary artery. A series of fluoren-9-yl ethyl amides (2) were synthesized and evaluated for human melatonin MT₁ and MT ₂ receptor binding. N-[2-(2,7-dimethoxyfluoren-9-yl)ethyl]propanamide (2b) was selected and evaluated in functional assays measuring intrinsic activity at the human MT₁ and MT₂ receptors and demonstrated full agonism at both receptors. The chronobiotic properties of 2b were demonstrated in both acute and chronic rat models where 2b produced an acute phase advance of 32 min at 1 mg/kg and chronically entrained free-running rats with a mean effective dose of 0.23 mg/kg. Compound 2b is significantly less efficacious than melatonin in constricting human coronary artery.

Full text of DOI:10.1016/j.bmc.2004.07.002

Bioorganic & Medicinal Chemistry 12 (2004) 4601–4611
Chronobiotic activity of N-[2-(2,7-dimethoxyfluoren-9-yl)ethyl]-
propanamide. Synthesis and melatonergic
pharmacology of fluoren-9-ylethyl amides
*
James R. Epperson, Marc A. Bruce, John D. Catt, Jeffrey A. Deskus,
Donald B. Hodges, George N. Karageorge, Daniel J. Keavy, Cathy D. Mahle,
Ronald J. Mattson, Astrid A. Ortiz, Michael F. Parker, Katherine S. Takaki,
Brett T. Watson and Joseph P. Yevich
Bristol-Myers Squibb Pharmaceutical Research Institute, 5 Research Pkwy, Wallingford, CT 06492-7660, USA
Received 20 January 2004; revised 29 June 2004; accepted 1 July 2004
Abstract—A series of fluoren-9-yl ethyl amides (2) were synthesized and evaluated for human melatonin MT and MT receptor
2
1
binding. N-[2-(2,7-dimethoxyfluoren-9-yl)ethyl]propanamide (2b) was selected and evaluated in functional assays measuring intrin-
sic activity at the human MT and MT receptors and demonstrated full agonism at both receptors. The chronobiotic properties of
b were demonstrated in both acute and chronic rat models where 2b produced an acute phase advance of 32min at 1mg/kg and
1
2
2
chronically entrained free-running rats with a mean effective dose of 0.23mg/kg. Compound 2b is significantly less efficacious than
melatonin in constricting human coronary artery.
ꢀ
2004 Elsevier Ltd. All rights reserved.
1
. Introduction
moting normal sleep patterns, and melatonin receptor
agonists may prove effective in the treatment of certain
sleep disorders.
Melatonin (1) is a neurohormone secreted primarily by
the pineal gland and involved in the regulation of circa-
dian and photoperiodic information. Melatonin levels
show a cyclical pattern––high at night and low during
1
2
Because the MT receptor has high levels of expression
1
1
5
in the SCN, we originally postulated that chronobiotic
properties would reside with this receptor subtype. More
recent evidence implicates the MT receptor for chrono-
3
the day. Melatonin exerts its effect, in part, through
4
specific G-protein coupled receptors. These receptors
include the human MT and MT receptors, which have
2
1
6
biotic properties. However, at the time this research
was conducted, our goals were to evaluate compounds
that had potent binding at both receptors. We now re-
port a series of novel fluoren-9-yl ethyl amides (2) pos-
sessing potent affinity at both human MT and MT
1
2
5
,6
been cloned. The MT and MT receptors are found
1
2
in different parts of the brain including the suprachias-
7
matic nucleus (SCN), the site of the biological clock.
The most noted physiological effect of melatonin is on
the sleep/wake cycle, and the roles of these receptors
1
2
8
on chronobiotic behavior are being pursued. The
chronobiotic effects of melatonin have led to a number
O
9
10
of potential therapeutic targets including jet lag, work
1
1
12
shift disturbances, seasonal affective disorder, de-
3
HN
R
1
layed sleep phase syndrome, and age related altera-
1
O
4
tions of the biological clock. Maintenance of a
suitable melatonin rhythm is felt to be important in pro-
MeO
HN
R
R
N
H
Keywords: Melatonin; Chronobiotic.
*
Corresponding author. Tel.: +1-203-677-6974; fax: +1-203-677-
900; e-mail: james.epperson@bms.com
1
2
6
Melatonin
0
968-0896/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2004.07.002

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J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
receptors. From this group of compounds, N-[2-(2,7-
dimethoxyfluoren-9-yl)ethyl]propanamide (2b) was
selected for further evaluation in acute and chronic rat
models and demonstrated chronobiotic efficacy compa-
rable to melatonin in both models.
AcO
CO2H
O
AcO
OMe
a
OMe
91%
9
10
b, c 100%, 74%
NH3Cl
2
. Results and discussion
O
HN
The syntheses of the 2,7-disubstituted fluorenyl com-
pounds described below were simplified as a result of
their symmetrical nature. The concise and general syn-
thesis of 2 lent itself to modifying the 2- and 7-positions.
Compound 2b serves as an example of the synthesis
HO
OMe
d, e
HO
OMe
96%
7
4%
1
2
11
2
o
(
Scheme 1, where R and R are methoxy). Other com-
pounds in this series were prepared using this synthesis
starting from appropriate aryl halides 3 and aryl boronic
acids 4, which were purchased or prepared by literature
methods. An additional series of compounds were made
from 2-hydroxy-7-methoxy amide 2o by alkylating the
phenolic moiety with a series of agents (Scheme 2).
f
66-91%
O
HN
RO
OMe
1
7
The synthesis of 2b began with the Suzuki coupling of
1
8
methyl 2-bromo-5-methoxy benzoate (3) with com-
mercially available 4-methoxyphenylboronic acid (4) in
subgenus of 2
8
4% yield. Whereas palladium acetate and tetrakistri-
Scheme 2. Reaction
NCCH PO(OEt) , NaH, DMF; (c) H
RCOCl, TEA, cat. DMAP, CH Cl ; (e) 1NNaOH, MeOH; (f) RI or
RBr, K CO , MeCN.
conditions:
(a)
SOCl
2
,
AlCl
3
;
(b)
phenylphosphine palladium failed to effect complete
conversion to the biphenyl compound, palladium di-
benzylideneacetone proved to be an effective catalyst
for this reaction. Ester 5 was then hydrolyzed, and the
resulting acid was cyclized by intramolecular Friedel–
Crafts acylation in refluxing thionyl chloride to provide
2
2
2
, Pd(C), CHCl
3
, EtOH; (d)
2
2
2
3
2
0
hydrogenation of the olefin and nitrile moieties of 7
to yield amine hydrochloride 8 in 91% yield. Subsequent
acylation was accomplished in 60% yield and generated
2b in 43% overall yield for the entire sequence. The syn-
thetic procedure proceeded with sufficient purity for the
preparation of 300g of 2b to be completed with only one
purification step––flash chromatography of the final
product.
2
,7-dimethoxyfluorenone (6) in 98% yield. Thus, the
symmetry of 4 removed all regiochemical issues related
to the Friedel–Crafts cyclization to 6. Horner–Emmons
olefination of 6 using diethyl cyanomethylphospho-
nate was accomplished in 79% yield followed by acidic
1
9
R1
CO2Me
R1
CO2Me (HO)2B
a
An additional method of preparing certain amides is
21
shown in Scheme 2. Acetoxymethoxy biphenyl 9 was
+
74-92%
R2
Br
R2
transformed into fluorene 11 using the methods de-
scribed above. The acidic nature of the hydrogenation
reaction leading from 10 to amine 11 resulted in the loss
of the phenolic acetyl group of 10. Because of this ex-
posed phenol moiety, amine 11 was diacylated and the
acyloxy intermediate was saponified to give amide 2o.
Amide 2o was then alkylated to give additional com-
pounds of structure 2.
3
4
5
9
(
2-98%
b, c
2 steps)
CN
O
R1
R2
R1
R2
d
6
9-86%
7
6
f
e
83-91%
O
2.1. Melatonin receptor pharmacology
NH3Cl
HN
R3
Compounds were assayed for human melatonin MT
and MT receptor binding using published methods.
Binding data are shown in Tables 1 and 2.
1
6
f or g
1-96%
2
R1
R2
R1
R2
6
Variation of the N-acyl group was explored in dimeth-
oxy compounds 2a–l (Table 1). Although there was per-
haps a slight trend toward better MT binding, overall
8
2
Scheme 1. Reaction conditions: (a) Pd
5ꢁC, 16h; (b) 1N Na OH, EtOH, 78 ꢁC; (c) SOCl
NCCH PO(OEt) , NAH, THF; (e) H , PtO , CHCl
2 2 2
RCOCl or (RCO) O, cat. DMAP, TEA, CH Cl ; (g) RNCO, CH Cl .
2
dba
3
, 2M N
2
aCO
3
, DME,
2
the compounds of this series were nonselective ligands.
Compounds 2a–c and 2g–h exhibited potent binding
affinity at both human MT and MT receptors. The
8
2
, 79ꢁC; (d)
2
2
2
2
3
, EtOH; (f)
2
2
1
2

J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4603
Table 1. Melatonin receptor binding affinities for compounds 2a–l
dialkylated compounds with long ethers were inactive
2v). Dialkylated ethers terminated by amines were
likewise inactive (2w and 2x). Mono ester 2y had mod-
(
O
HN
R3
erate MT affinity with little MT affinity, while mono
2
1
acid 2z was inactive at both receptors. Mono fluoro
compound 2aa had good MT affinity and moderate
MeO
OMe
2
MT1 affinity, while difluoro compound 2bb had
decreased MT2 affinity and lost most affinity at the
3
R
MT receptor. Compounds 2aa and 2bb again highlight
1
Compound
MT
1
K
i
(nM)
2 i
MT K (nM)
the importance of having one methoxy group at the 2-
or 7-position.
2
2
2
2
2
2
2
2
2
2
2
2
a
b
c
d
e
f
Me
Et
2.3
2.0
1.9
0.55
0.28
0.29
n-Pr
n-Bu
i-Pr
The necessity for having at least one methoxy group in
the 2- or 7-position in the preceding compounds gives
rise to a pharmacophore that is isosteric to melatonin.
The role of the remaining aryl ring was less clear. The
size and variety of substituents that could be tolerated
on this ring suggests that there is little real interaction
with the MT or MT receptor binding site.
140
10
2.3
16
33
59
t-Bu
c-Pr
c-Bu
c-Pentyl
g
h
i
4.1
3.3
150
28
2.6
350
0.40
0.47
4.4
37
j
CH
CH
2
OMe
Cl
0.96
0.38
1
2
k
l
2
NHEt
14
0.30
These binding studies suggested further evaluation of a
compound for functional and chronobiotic activity,
and we selected compound 2b. While (ꢀ)-2n showed
similar activity to compound 2b, it offered no advantage
due to the added complexity of the chiral center. Com-
pound 2b, on the other hand, benefited from its symme-
try and synthetic simplicity.
Melatonin
K
i
values are the mean of at least three separate determinations run at
five different concentrations with radioligand at the K concentration.
d
Standard errors were typically ±20% of the mean value.
acetamide, propanamide, and butyramide were equipo-
tent, while the valeramide had significantly less binding
affinity (examples 2a–d). These small linear amides also
demonstrated greater affinity than small branched
amides (examples 2e and 2f). Cyclopropyl and cyclo-
butyl amides 2g and 2h showed potent affinity, while
cyclopentyl amide 2i had modest affinity. Chloroacetyl
compound 2k had good affinity while methoxy acet-
amide 2j demonstrated good binding only at the MT2
receptor. N-Ethyl urea 2l also showed some selectivity
2.2. Functional activity of 2b
Melatonin and 2b were evaluated for functional activity
2
2
in adenyl cyclase assays (Fig. 1). Melatonin induced a
concentration-dependent decrease in forskolin-stimu-
lated cAMP accumulation in NIH-3T3 cells stably
expressing either MT1 or MT2 receptors (MT1
EC50 = 0.80± 0.19nM and MT EC = 2.06± 1.12nM).
2
50
for the MT receptor, although affinity at both receptors
2
was attenuated.
Compound 2b also demonstrated full agonism and sim-
ilar potency at the MT1 and MT2 receptors (MT1
EC50 = 0.85± 0.25nM and MT EC = 0.64± 0.28nM).
2
50
Variation at the 2- and 7-positions of the fluorene was
explored in compounds 2m–dd (Table 2). When the 2-
and 7-positions are differentially substituted, as in 2n,
the C-9 carbon becomes chiral. Thus, many of the com-
pounds in Table 2 are chiral. Because of the good bind-
ing affinity of racemic 2n, the enantiomers were
separated by chiral chromatography and separately
evaluated. However, other compounds were evaluated
as racemic mixtures.
Data shown is a composite of three separate experi-
ments each performed in duplicate.
2.3. Chronobiotic activity of 2b
In order to validate rat in vivo studies, 2b was further
evaluated in binding studies with rat melatonin recep-
tors. Compound 2b bound to the rat MT receptor with
1
a K =1.70nM and to the rat MT receptor with a
i
2
K =0.26nM. Thus, 2b binds to both human and rat re-
i
The importance of having at least one methoxy group
was demonstrated in compounds 2m and (ꢀ)-2n. Com-
pound 2m was significantly less potent than 2b, while
ceptors with similar affinity and in a nonselective man-
ner.
(
of the enantiomers of 2n resided predominantly in the
ꢀ)-2n was equipotent to 2b. The MT binding affinity
The chronobiotic properties of 2b were assessed in rats
using both an acute treatment paradigm and a chronic
1
2
3
(
MT receptor. Diethoxy compound 2p had potent
ꢀ)-isomer, while both enantiomers were potent at the
administration paradigm. In the acute model, a single
injection of 2b, melatonin, or vehicle was administered
approximately 2h before the expected onset of activity
in free-running rats maintained in constant darkness.
Compound 2b dose-dependently produced a phase ad-
vance in the onset of wheel activity. The phase advance
at 1mg/kg was 32min (Fig. 2). Melatonin (1mg/kg) pro-
duced a similar phase advance of 28min. Vehicle gave
no phase advance.
2
MT binding and significantly less MT affinity. Trans-
2
1
forming one or both of the methoxy groups into hydroxy
groups at the 2- and 7-positions decreased affinity (2o
and 2cc). Interestingly, as long as one methoxy group
was intact in the 2-position, the 7-position could be sub-
stituted with a variety of large ethers and still retained
relatively good binding affinity, while symmetrically

4604
J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
Table 2. Melatonin receptor binding affinities for compounds 2m-dd
O
HN
R3
R1
R2
1
2
3
Compound
Melatonin
R
R
R
MT
1
K
i
(nM)
2 i
MT K (nM)
0.40
2.0
0.30
0.28
6.4
2
2
b
MeO
H
MeO
H
Et
nPr
Et
Et
Et
Et
Et
m
66
2.5
42
(
ꢀ)-2n
+)-2n
MeO
MeO
MeO
EtO
MeO
H
0.50
2.7
(
H
2
2
2
o
p
q
HO
EtO
83
150
29
2.1
4.8
CH (CH
3
2
2
)
)
4
O
5.5
2r
MeO
CH (CH
3
10
O
Et
7.9
3.8
7.1
MeO
O
2s
MeO
Et
17
2
2
2
t
MeO
MeO
Ph(CH
PhCH
2
CH
2
O
Et
Et
Et
47
3.5
>500
27
13
u
v
Ph(CH
Ph(CH
2
)
)
3
6
O
2
)
6
2
O
2
O
>500
2w
Et NCH
2
CH
2
O
Et
2
NCH
2
CH
2
O
Et
>500
>500
>500
N
O
N
O
2
x
Et
>500
O
O
2
2
2
2
2
2
y
MeO
MeO
MeO
F
MeO CCH
2
2
O
Et
Et
Et
Et
Et
Et
290
>500
15
13
140
z
HO
F
2
2
CCH O
aa
bb
cc
dd
1.8
F
HO
200
>500
>500
11
>500
96
HO
AcO
AcO
i d
K values are the mean of at least three separate determinations run at five different concentrations with radioligand at the K concentration. Standard
errors were typically 20% of the mean value.
Compound 2b was also assessed in a chronic entrain-
ment animal model. Rats were maintained in a 12h
light–dark cycle until a reliable pattern was established
between the onset of darkness and the onset of running
wheel activity. The rats were then maintained in con-
stant darkness to allow each animalꢀs endogenous activ-
ity-rest cycle to be expressed. In the rat, this is typically
longer than 24h. The animals then received 2b (a dose
ranging from 0.01 to 1.0mg/kg), melatonin (1mg/kg),
or vehicle at the same time of day for 39 consecutive
days. Animals entrained to 2b (for 1mg/kg, n = 10 and
represents the administration of compound or vehicle.
In the first actogram, no effect was seen in the animalꢀs
activity-rest cycle when vehicle was administered. In
the second and third actograms, the animals entrained
to the administration of compound. In the second acto-
gram one can clearly see the entrainment occurred when
the administration was at the onset of activity.
2.4. Vascular effects of 2b
Melatonin mediates vasoconstriction in human coro-
2
4
8
animals became entrained) and melatonin (n = 9),
nary artery preconstricted with KCl. The ability to
constrict vascular smooth muscle, particularly human
coronary artery, would be undesirable in any melatoner-
gic clinical candidate. Preliminary evaluation in human
coronary artery showed 2b to be less efficacious than
melatonin (Fig. 4). The Emax for 2b was 0.23g (n = 8
rings from 1 donor) while the Emax for melatonin was
0.83g (n = 28 from 3 donors). This data correlated with
in-house data from pig coronary artery, rat cerebral
artery, and rat caudal artery. In all models, the efficacy
of 2b was significantly less than melatonin.
while no animals entrained to vehicle (n = 7). The med-
ian effective dose for 2b was 0.23mg/kg. Entrainment oc-
curred when the time of administration coincided with
the onset of activity. Examples of actograms from three
different rats are shown in Figure 3. In these actograms,
each horizontal line represents one 24h period that is
double-plotted (the 24h period is repeated) for ease of
viewing. Day one is the top line and day 39 is the bottom
line. Dark areas of each line represent activity and light
areas represent the absence of activity. The vertical bar

J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4605
3. Conclusion
We have discovered a series of fluorenes, which are po-
tent melatonergic ligands. Small linear and cyclic amides
in the series demonstrate potent binding at both human
MT and MT receptors. Compound 2b was shown to
1
2
be an agonist at both human MT and MT receptors.
1
2
Compound 2b was effective in both acute and chronic
rat models on a level comparable to melatonin. In acute
rat studies, compound 2b produced an acute phase ad-
vance of 32min at 1mg/kg. In chronic studies, com-
pound 2b entrained free-running rats with a mean
effective dose of 0.23mg/kg. In contrast to chronobiotic
activity, compound 2b is distinguished from melatonin
by being significantly less efficacious at constricting
human coronary artery, an important criteria for any
clinical candidate.
4. Experimental
4.1. General
Unless otherwise stated, all reagents were used from
the commercial sources without further purification.
Chromatographic purification was by way of flash
chromatography unless otherwise stated. Melting points
are uncorrected. NMR data was collected on a
Bruker AC-300 spectrometer and are reported conven-
tionally.
0 0
.2. 4,4 -Dimethoxy-[1,1 -biphenyl]-2-carboxylic acid,
methyl ester (5b)
4
Figure 1. The effect of melatonin and 2b on forskolin-stimulated cyclic
AMP accumulation in NIH-3T3 cells stably expressing the human
MT
1
or MT
2
receptor. Data shown is a composite of three separate
Methyl 2-bromo-5-methoxybenzoate (1.60g, 6.53mmol),
4-methoxyphenylboronic acid (1.30g, 8.55mmol), and
experiments each performed in duplicate. Nonlinear regression anal-
ysis yielded EC50 values of 0.80± 0.19 and 0.85± 0.25nM and Emax
values (% inhibition) of 42± 5 and 44± 4 for melatonin and 2b,
tris(dibenzylideneacetone)dipalladium
0
(0)
.22mmol) were added to dimethoxyethane (25mL)
(0.20g,
respectively, at the MT
.64± 0.28nM and Emax values (% inhibition) of 52± 6 and 50± 3 for
melatonin and 2b, respectively, at the MT receptor.
1
receptor and EC50 values of 2.06± 1.12 and
and 2M sodium carbonate (25mL). The suspension
was stirred at reflux for 16h at which time TLC analysis
indicated the reaction was complete. The reaction
mixture was filtered and extracted with ethyl acetate.
The combined organic extracts were dried and the sol-
0
2
vent removed by rotary evaporation to afford 1.50g
1
(
84%) of 5b, mp 55–56ꢁC. H NMR (CDCl ) d
3
7.30–7.27 (m, 2H), 7.19 (d, J = 6.6Hz, 2H), 7.04 (dd,
J = 8.5, 2.8Hz, 1H), 6.90 (d, J = 6.6Hz, 2H), 3.85 (s,
H), 3.83 (s, 3H), 3.65 (s, 3H); C NMR (CDCl ) d
1
3
3
3
169.2, 158.7, 158.4, 134.6, 133.4, 131.9, 131.6, 129.5,
117.5, 114.3, 113.5, 55.6, 55.3, 52.1. Anal. (C H O )
C, H.
1
6
16
4
4.3. 2,7-Dimethoxy-9H-fluoren-9-one (6b)
Ester 5b (10.80g, 39.70mmol) was hydrolyzed with 1N
sodium hydroxide (80mL) in refluxing ethanol
(500mL). The cooled reaction mixture was extracted
with methylene chloride and acidified with 1Nhydro-
chloric acid. The acidic solution was then extracted with
methylene chloride. The organic extracts were com-
bined, dried with magnesium sulfate, and filtered. The
filtrate was concentrated by rotary evaporation to give
9.00g (88%) of the acid.
Figure 2. Acute effects of 2b on circadian phase advance. Mean phase
advance of running wheel activity rhythm onset after a single injection
of 2b or vehicle.

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J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
Figure 3. Entrainment of rats given chronic injections of vehicle, melatonin, or 2b. Each actogram represents the results for one animal. Each
horizontal line of an actogram represents a 24 period (double-plotted for ease of viewing). Day 1 is the top line and day 39 is the bottom line. The
dark areas of a given line represent animal activity. The vertical bar represents the time of injection.
washed with hexane and concentrated by rotary evapo-
ration to produce 8.76g (79%) of 7b as an orange semi-
1
solid. H NMR (300MHz, CDCl ) d 7.92 (d, J = 2.1Hz,
3
1
H), 7.32 (dd, J = 6.7, 2.1Hz, 2H), 7.03 (d, J = 2.3Hz,
H), 6.89 (dd, J = 6.7, 2.3Hz, 2H), 5.99 (s, 1H), 3.85
1
+
s, 3H), 3.82 (s, 3H); MS (DCI) MH = 264.
(
4
.5. 2-(2,7-Dimethoxy-9H-fluoren-9-yl)ethylamine (8b)
A suspension of 7b (7.72g, 0.033mol), PtO (0.77 g),
2
CHCl (23mL), in EtOH (150mL) was hydrogenated
3
on a Parr shaker (50psi) for 18h. The mixture was fil-
tered and the filtrate concentrated to afford a white so-
lid. The solid was washed with ether and dried in
vacuo to obtain 6.94g (69%) of 8b as a white solid. This
crude solid was used directly in subsequent acylations.
Figure 4. The effect of melatonin (n = 28 rings from three donors) and
b (n = 8 rings from one donor) on human coronary artery precon-
tracted with 30mM KCl. Nonlinear regression analysis yielded an
max = 0.83± 0.07g for melatonin and Emax = 0.23± 0.04 for 2b.
2
4.6. General procedure for acylating amine 8a
E
A solution of 8a (1equiv), triethylamine (2.2equiv), and
DMAP (1equiv) in methylene chloride was cooled to
0
ꢁC and the appropriate acid chloride (1.1equiv) was
9
.00g (34.88mmol) of the acid was dissolved in thionyl
slowly added. The reaction was warmed to room tem-
perature and stirred for 1h. The reaction was quenched
with 1NHCl and extracted with methylene chloride.
The organic layers were washed with 1NHCl, 10%
chloride (250mL) and stirred at reflux for 6h at which
time TLC analysis indicated the reaction was complete.
The solution was cooled and the solvent removed by
rotary evaporation to give 8.20g (98%) of 6b as a red
NaHCO , satd NaCl, dried over magnesium sulfate,
3
and concentrated. The residue was purified by flash
chromatography.
1
solid, mp 116–118ꢁC. H NMR (CDCl ) d 7.22 (d,
3
J = 6.6Hz, 2H), 7.17 (d, J = 2.8Hz, 2H), 6.89 (dd,
J = 8.5, 2.8Hz, 1H).
4
(
.4. (2,7-Dimethoxy-9H-fluoren-9-ylidene)acetonitrile
7b)
4.7. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]acetamide (2a)
Prepared from 8a according to the general procedure
using acetyl chloride. Compound 2a was obtained as a
Diethyl cyanomethylphosphonate (7.43g, 0.042mol)
was slowly added to a suspension of NaH (1.61g,
0
1
white solid (79%), mp 147–148ꢁC.
H
N
MR
.067mol) in THF (200mL) at room temperature. The
(300MHz, CDCl ) d 7.52 (d, J = 8.3Hz, 2H), 7.01 (d,
3
reaction was stirred for 15min and the solution turned
pale yellow. A solution of 6b (8.89g, 0.042mol) in
THF (100mL) was added dropwise and the reaction
was stirred for 16h. The solvent was removed in vacuo
and the residue dissolved in methylene chloride. The or-
ganic solution was washed with water, dried over mag-
nesium sulfate, and concentrated to produce an orange
solid. This residue was dissolved in acetonitrile and
J = 2.1Hz, 2H), 6.89 (d, J = 2.3Hz, 1H), 6.85 (d,
J = 2.3Hz, 1H), 4.94 (s, 1H), 3.97 (t, J = 5.1Hz, 1H),
3.83 (s, 6H), 3.02 (q, J = 6.6Hz, 2H), 2.27 (q,
1
3
J = 6.6Hz, 2H), 1.65 (s, 3H); C NMR (75MHz,
CDCl ) d 169.8, 158.7, 147.6, 133.9, 119.9, 113.1,
110.1, 55.6, 45.6, 36.2, 31.8, 22.9; IR (KBr) 3268,
3
ꢀ
1
+
1646, 1574, 1240cm ; MS (DCI) MH = 312; Anal.
(C H N O ) C, H, N .
1
9
21
1
3

J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4607
4
(
.8. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]propanamide
2b)
133.9, 119.9, 113.0, 110.2, 55.5, 45.6, 36.0, 35.4, 32.6,
+
19.3. MS (ESI) MꢀH = 340. Anal. (C H NO ) C,
2
1
25
3
H, N.
Prepared from 8a according to the general procedure
using propanoyl chloride. Compound 2b was obtained
1
4.12. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]-2,2-dimeth-
ylpropanamide (2f)
as a white solid (60%), mp 139–140ꢁC. H N MR
(
300MHz, CDCl ) d 7.52 (d, J = 8.3Hz, 2H), 7.06 (d,
3
2
(
H), 6.88 (d, J = 2.3, 1H), 6.85 (d, J = 2.3, 1H), 4.87
s, 1H), 3.98 (t, J = 5.1Hz, 1H), 3.83 (s, 6H), 3.04 (q,
J = 6.5Hz, 2H), 2.29 (q, J = 6.6Hz, 2H), 1.96–1.82 (m,
Prepared from 8a by the general procedure using piva-
loyl chloride. Compound 2f was obtained as a white so-
ꢀ1
1
1
3
lid (51%), mp 88–89ꢁC. IR (KBr) 1628, 1528cm ; H
2
H), 0.92 (t, J = 7.6Hz, 3H); C NMR (75MHz,
NMR (CDCl ) d 7.53 (d, J = 8.3Hz, 2H), 7.01 (d,
3
CDCl ) d 173.4, 158.8, 147.7, 133.9, 119.9, 113.0,
3
J = 2.0Hz, 2H), 6.85 (dd, J = 8.3, 2.4Hz, 2H), 5.11 (br
s, 1H), 4.00–3.97 (m,1H), 3.83 (s, 6H), 3.06–3.00 (m,
1
1
10.1, 55.6, 45.7, 36.1, 31.9, 29.5, 9.49; IR (KBr) 3260,
640, 1240cm
ꢀ1
+
MS (DCI) MH = 326; Anal.
;
13
H), 2.34–2.28 (m, 2H), 0.90 (s, 9H); C NMR (CDCl3)
2
(
C H N O ) C, H, N .
20 23 1 3
d 178.0, 158.8, 147.6, 133.9, 119.9, 113.0, 110.3, 55.5,
+
4
5.5, 38.3, 36.2, 31.7, 27.2. MS (ESI) MꢀH =354.
Anal. (C H NO ) C, H, N.
22 27
4
(
.9. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]butanamide
2c)
3
4.13. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]cycloprop-
ane carboxamide (2g)
Prepared from 8a according to the general procedure
using butyryl chloride. Compound 2c was obtained as
1
a white solid (74%), mp 126–127ꢁC. H N MR
Prepared from 8a according to the general procedure
using cyclopropanecarbonyl chloride. Compound 2g
(
300MHz, CDCl ) d 6.75 (d, J = 8.3Hz, 2H), 7.03 (d,
3
J = 2.1Hz, 2H), 6.90 (d, J = 2.3Hz, 1H), 6.88 (d,
J = 23Hz, 1H), 4.92 (br s, 1H), 3.99 (t, J = 5.1Hz,
was obtained as a viscous oil (65%), mp 152–153ꢁC.
1
H NMR (300MHz, CDCl ) d 87.52 (d, J = 8.30Hz,
3
1
H), 3.85 (s, 6H), 3.07 (q, J = 6.7Hz, 2H), 2.30 (q,
J = 6.7Hz, 2H), 1.84 (t, J = 7.2Hz, 2H), 1.51–1.38 (m,
2H), 7.02 (s, 2H), 6.08 (d, J = 2Hz, 1H), 6.85 (d,
J = 2Hz, 1H), 5.05 (br s, 1H), 3.98 (t, J = 5.1Hz, 1H),
1
H), 0.84 (t, J = 7.3Hz, 3H); C NMR (75MHz,
3
2
3.83 (s, 6H), 3.06 (q, J = 6Hz, 2H), 2.28 (q, J = 6.6Hz,
CDCl ) d 172.6, 158.7, 147.6, 133.9, 119.9, 113.0,
3
2
H), 0.95–0.08 (m, 1H), 0.81–0.78 (m, 2H), 0.60–0.54
110.2, 55.6, 45.6, 38.5, 36.0, 32.0, 28.7, 18.9, 13.7, 4.8;
IR (KBr) 3300, 1634, 1540, 804cm ; MS (DCI)
13
(m, 2H); C NMR (75MHz, CDCl ) d 174.6, 158.7,
ꢀ
1
3
1
1
47.7, 134.0, 119.8, 113.1, 110.1, 55.5, 45.7, 36.3, 32.1,
4.5, 6.8; IR (KBr) 3300, 1640, 1240, 1030, 800cm
+
MH = 340; Anal. (C H N O ) C, H, N .
ꢀ1
2
1
25
1
3
;
+
MS (DCI) MH = 338. Anal. (C H N O Æ0.5H O) C,
2
1
23
1
3
2
H, N.
4.10. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]-pentan-
amide (2d)
4.14. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]cyclobutane
carboxamide (2h)
Prepared from 8a by the general procedure using vale-
royl chloride. Compound 2d was obtained as a white
solid (66%), mp 130–131ꢁC. IR (KBr) 3306, 1634,
Prepared from 8a by the general procedure using cyclo-
butanecarbonyl chloride. Compound 2h was obtained as
a white solid (61%), mp 145–146ꢁC. IR (KBr) 3310,
ꢀ
1
1
1
540, 1256cm
;
H NMR (CDCl ) d 7.55 (d,
3
J = 8.3Hz, 2H), 7.03 (d, J = 1.8Hz, 2H), 6.89 (dd,
J = 8.3, 2.1Hz, 2H), 4.94 (br s, 1H), 4.01–3.48 (m,
ꢀ1
1
1632, 1540cm
;
H NMR (CDCl ) d 7.53 (d,
3
1
2
2
3
H), 3.85 (s, 6H), 3.10–3.03 (m, 2H), 2.33–2.27 (m,
H), 1.86 (t, J = 7.3Hz, 2H), 1.40 (pent, J = 6.8Hz,
H), 1.23 (sex, J = 6.9Hz, 2H), 0.85 (t, J = 7.2Hz,
J = 8.3Hz, 2H), 7.01 (d, J = 7.0Hz, 2H), 6.88 (dd,
J = 8.3, 2.4Hz, 2H), 4.80 (br s, 1H), 3.98 (t,
J = 7.0Hz, 1H), 3.83 (s, 6H), 3.04–3.02 (m, 2H), 2.62
(pent, J = 8.5Hz, 1H), 2.30–2.29 (m, 2H), 1.98–1.94
1
3
H); C NMR (CDCl ) d 172.8, 158.7, 147.6, 133.9,
3
1
3
1
19.8, 113.0, 110.2, 55.5, 45.6, 36.3, 36.1, 31.9, 27.5,
(
m, 6H); C NMR (CDCl ) d 174.5, 158.7, 147.6,
3
+
2
C, H, N.
2.3, 13.6. MS (ESI) MꢀH = 354. Anal. (C H NO )
2
2
27
3
133.9, 119.9, 113.1, 110.1, 55.5, 45.7, 39.7, 36.6, 31.9,
+
2
5.1, 17.4. MS (ESI) MꢀH = 352. Anal. (C H NO )
2
2
25
3
C, H, N.
4.11. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]-2-methyl-
propanamide (2e)
4.15. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]cyclopentane
carboxamide (2i)
Prepared from 8a by the general procedure using isobu-
tyryl chloride. Compound 2e was obtained as a white
solid (57%), mp 144–145ꢁC. IR (KBr) 3324, 1646,
Prepared from 8a by the general procedure using cyclo-
pentanecarbonyl chloride. Compound 2i was obtained
ꢀ
1
1
1
1
554cm
;
H NMR (CDCl ) d 7.55 (d, J = 8.3Hz,
as viscous oil (65%). H NMR (300MHz, CDCl ) d
3
3
2
H), 7.04 (m, 2H), 6.89 (dd, J = 8.3, 2.2Hz, 2H), 4.96
br s, 1H), 4.01 (m, 1H), 3.85 (s, 6H), 3.10–3.03
7.53 (d, J = 8.3Hz, 2H), 7.03 (d, J = 2.3Hz, 2H), 6.87
(dd, J = 8.3, 2.3Hz, 2H), 5.0 (br s, 1H), 3.97 (t,
J = 5.1Hz, 1H), 3.83 (s, 6H), 3.06 (q, J = 6.1Hz, 2H),
2.27 (q, J = 6.6Hz, 2H), 2.13 (m, 1H), 1.57 (m, 8H);
(
(
(
m, 2H), 2.02 (pent, J = 6.8Hz, 1H), 0.96 (s, 3H), 0.93
s, 3H); C NMR (CDCl ) d 176.5, 158.7, 147.6,
1
3
3

4608
J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
1
3
C NMR (75MHz, CDCl ) d 175.7, 158.6, 147.6, 133.8,
4.20. N-[2-(2-Methoxyfluoren-9-yl)ethyl]propanamide (2n)
3
1
2
19.8, 112.9, 110.1, 55.4, 45.7, 45.5, 36.0, 32.0, 30.0,
5.7; Anal. (C H N O ) C, H, N .
Prepared using phenylboronic acid and employing the
methods of Scheme 1. Separated by chiral HPLC
2
3
27
1
3
(
Chiracel OD-R, 4.6mm · 25cm, 0.7mL/min at 0.5kpsi
4.16. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]methoxy-
acetamide (2j)
using acetonitrile and water with a 0.5M sodium perchlo-
rate buffer). (ꢀ)-2n. Mp 117–119ꢁC; Retention time:
+
2
(
9.4min; [a]D ꢀ29.6; MS (DCI) MH = 296. Anal.
Prepared from 8a according to the general procedure
using methoxyacetyl chloride. Compound 2j was ob-
C H NO ) C, H, N. (+)-2n. Mp 118–120ꢁC; Reten-
19 21
2
+
1
tion time: 32.6min; [a]D 32.2; MS (DCI) MH = 296.
Anal. (C H NO ) C, H, N .
tained as viscous oil (74%), mp 94–95ꢁC. H N MR
(
J = 2.1Hz, 2H), 6.89 (d, J = 2.3Hz, 1H), 6.85 (d,
300MHz, CDCl3) d 7.52 (d, J = 8.3Hz, 2H), 7.01 (d,
19 21
2
4
(
.21. N-[[(2,7-Diethoxy)-9-fluorenyl]ethyl]propanamide
2p)
J = 2.3Hz, 1H), 4.94 (s, 1H), 3.97 (t, J = 5.1Hz, 1H),
3.83 (s, 6H), 3.02 (q, J = 6.6Hz, 2H), 2.27 (q,
J = 6.7Hz, 2H), 1.65 (s, 3H); C NMR (75MHz,
1
3
Prepared in an analogous fashion to 2b and obtained
as a white solid, mp 125–128ꢁC. IR (KBr) 1644,
1
(
CDCl ) d 169.2, 158.7, 147.4, 133.9, 119.9, 113.1,
3
1
10.1, 71.8, 58.9, 55.6, 45.6, 35.4, 32.1, 7.7; IR (KBr)
298, 1646, 1574, 1240cm ; MS (DCI) MH = 312.
ꢀ1
1
ꢀ
1
+
550, 1236, 1048cm ; H NMR (DMSO-d ) d 7.24
6
3
Anal. (C H N O ) C, H, N .
t, J = 5.4Hz, 1H), 7.59 (d, J = 8.1Hz, 2H), 7.08 (s,
2
0
23
1
4
2
3
1
H), 6.86 (d, J = 8.4Hz, 2H), 4.03 (q, J = 7.2Hz, 4H),
.87 (t, J = 5.7Hz, 1H), 2.87 (q, J = 6.3Hz, 2H),
.99 (m, 4H), 1.32 (t, J = 6.9Hz, 6H), 0.93 (t,
4
.17. N-[2-(2,7-Dimethoxyfluoren-9-yl)ethyl]-2-chloro-
acetamide (2k)
+
J = 7.5Hz, 3H); MS (ESI) MH = 354. Anal.
(C H NO ) C, H, N .
22 27 3
Prepared by the from 8a general procedure using chloro-
acetyl chloride. Compound 2k was obtained as a white
solid (62%), mp 122–123ꢁC. IR (KBr) 1640,
4
.22. 2-Acetoxy-7-methoxyfluoreneone (10)
ꢀ
542cm ; H NMR (CDCl ) d 7.53 (d, J = 8.3Hz,
3
1
1
1
2
2
3
A solution of acid 9 (3.20g, 11.2mmol) in thionyl chlo-
ride was stirred at reflux for 4h. The solution was cooled
to room temperature and concentrated in vacuo to
afford a yellow residue. The residue was dissolved in
dichloromethane and cautiously treated with aluminum
chloride (1.50g, 11.2mmol). After stirring for 16h, the
reaction mixture was poured into a slurry of 1NHCl
and ice. The mixture was extracted with dichlorometh-
ane and the extracts dried over magnesium sulfate, fil-
tered, concentrated by rotary evaporation. The crude
product was purified by column chromatography (15%
H), 7.02 (d, J = 2.0Hz, 2H), 6.88 (dd, J = 8.3, 2.2Hz,
H), 6.04 (br s, 1H), 4.02–3.94 (m, 1H), 3.84 (s, 6H),
.77 (s, 2H), 3.09–3.02 (m, 2H), 2.39–2.33 (m, 2H);
1
3
C
NMR (CDCl ) d 165.5, 158.8, 147.2, 134.0, 120.0,
1
3
13.1, 110.1, 55.5, 45.5, 42.3, 36.3, 31.3. MS (ESI)
ꢀ
MꢀH 344. LC retention time 10.9min (45% MeCN/
H O, no buffer, 1.5mL/min C-18 Zorbax).
2
0
4.18. N-[2-(2,7-Dimethoxy-9H-fluoren-9-yl)ethyl]-N -eth-
ylurea (2l)
ethyl acetate/hexane) to afford 2.7g (90%) of 10 as a
1
Ethyl isocyanate (25mg, 0.35mmol) was slowly added to
a suspension of 8b (100mg, 0.33mmol) in methylene
chloride at 0ꢁC. The reaction was allowed to warm to
room temperature, quenched with 1NHCl, and ex-
tracted with methylene chloride. The organic extracts
red solid. H NMR (CDCl ): d 7.33 (dd, J = 4.9,
3
1
J = 12.0, 2.5Hz, 1H), 7.05 (d, J = 2.3Hz, 1H), 6.90
.4Hz, 2H), 7.24 (d, J = 2.2Hz, 1H), 7.11 (dd,
1
3
(dd, J = 8.2, 2.5Hz, 1H), 3.78 (s, 3H), 2.24 (s, 3H);
C
NMR (CDCl ): d 192.7, 169.3, 160.8, 150.7, 142.3,
3
were washed with solutions of 10% NaHCO and satd
3
136.6, 136.2, 135.8, 127.5, 121.4, 120.6, 120.3, 118.2,
1
+
09.7, 55.8, 21.1; MS (DCI) MH = 270. Anal.
NaCl, dried with magnesium sulfate, and concentrated
by rotary evaporation. The crude product was purified
by flash chromatography to afford 115mg (93%) of 2l
(
C H O Æ0.25H O) C, H.
16 12 4 2
1
as a tan solid, mp 143–145ꢁC. H NMR (300MHz,
4.23. 2-Hydroxy-7-methoxy-9-ethylaminofluorene hydro-
chloride (11)
CDCl ) d 7.52 (d, J = 8.4Hz, 2H), 7.01 (m, 2H), 6.86
3
(
(
2
dd, J = 9.0, 2.1Hz, 2H), 3.98 (t, J = 5Hz, 1H), 3.38
s, 6H), 2.97–2.90 (m, 4H), 2.27 (dt, J = 6.3, 5.7Hz,
Diethylcyanomethyl phosphate (1.57mL, 9.69mmol,
1
H), 1.00 (t, J = 8.0Hz, 3H); C NMR (75MHz,
3
1
.1equiv) was added dropwise to a suspension of so-
dium hydride (60% in mineral oil, 0.32g, 9.69mmol,
.1equiv) in THF at room temperature under nitrogen.
CDCl ) d 158.74, 157.85, 147.88, 133.90, 119.84,
3
1
13.01, 110.12, 55.55, 45.62, 37.08, 35.21, 32.66, 15.24;
IR (KBr) 1628, 1578, 1242, 1028cm ; MS (DCI)
1
ꢀ
1
After stirring 30min, compound 10 (2.36g, 8.81mmol,
1equiv) in THF was added dropwise. The reaction
was stirred at room temperature for 16h. The reaction
mixture was quenched with water and extracted with
ethyl ether. The extracts were dried over magnesium sul-
fate, filtered, and concentrated by rotary evaporation to
give 2.85g (quantitative yield) of the crude nitrile as a
red-brown solid.
+
MH = 341. Anal. (C H N O Æ0.07H 0) C, H, N.
2
0
24
2
3
2
4
.19. N-[2-(9H-Fluoren-9-yl)ethyl]propanamide (2m)
Prepared from commercially available fluorenone by the
methods used for 2b, mp 127–128ꢁC. MS (DCI)
+
MH = 280. Anal. (C H NO) C, H, N.
1
9
21

J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4609
A suspension of the crude nitrile (21.5g, 73.9mmol) and
0% palladium on carbon (7.0g) in absolute ethanol and
chloroform (5:1) was hydrogenated on a Parr shaker at
5psi. After 16h at room temperature, the reaction
mixture was filtered through Celite and concentrated
in vacuo to an oil. The oil was dissolved in ethyl ether
and extracted with 1NHCl. The aqueous layer was
concentrated to dryness to afford 1.84g (7.5%) of an
4.26. N-[2-Undecoxy-7-methoxyfluoren-9-yl]ethyl prop-
anamide (2r)
1
4
Prepared from 2o and obtained as a yellow solid, mp 91–
1
94ꢁC. H NMR (CDCl ) d 7.52 (dd, J = 8.3, 2.1Hz,
3
2H), 7.01 (s, 2H), 6.87 (d, J = 8.4Hz, 2H), 4.85 (br s,
1H), 3.97 (m, 3H), 3.83 (s, 3H), 3.03 (q, 2H), 2.29 (q,
J = 5.5Hz, 2H), 1.85 (q, J = 7.7Hz, 2H), 1.25 (br,
off-white solid, which was used without further purifica-
18H), 0.92 (t, J = 7.7Hz, 3H), 0.86 (t, J = 7.6Hz, 3H);
C NMR (CDCl ) d 173.5, 158.8, 158.4, 147.7, 134.1,
1
13
tion. H NMR (DMSO-d ) d 9.60 (s, 1H), 8.04 (br s,
6
3
2
7
1
H), 7.57 (d, J = 8.3Hz, 1H), 7.51 (d, J = 8.3Hz, 1H),
.08 (s, 1H), 6.93 (s, 1H), 6.88 (dd, J = 8.4, 2.3Hz,
H), 6.75 (dd, J = 8.4, 2.3Hz, 1H), 3.90 (m, 1H), 3.78
133.8, 119.9, 113.7, 113.2, 110.9, 110.3, 68.5, 55.7,
45.8, 36.2, 32.0, 31.9, 29.7, 29.5, 29.4, 26.2, 22.8, 14.2,
+
9.6; MS (ESI) MꢀH = 464. Anal. (C H NO Æ0.75-
3
0
43
3
(s, 3H), 2.40 (m, 2H), 2.26 (m, 2H); MS (DCI)
M+H = 256.
H O) C, H, N.
2
+
4.27. N-[2-(2-Methoxy-7-(3-(3-methoxyphenyl)propox-1-y))-
fluoren-9-yl]ethyl propanamide (2s)
4.24. N-[2-(Hydroxy-7-methoxyfluoren-9-yl)]ethyl prop-
anamide (2o)
1
Prepared from 2o and obtained as a viscous oil. H
NMR (CDCl ) d 7.54 (d, J = 8.3Hz, 2H), 7.21 (t,
J = 7.8Hz, 2H), 7.03 (s, 2H), 6.91–6.73 (m, 4H), 4.92
A suspension of 2-hydroxy-7-methoxy-9-ethylaminoflu-
orene hydrochloride (1.84g, 6.30mmol), triethylamine
3
(
3
(
br s, 1H), 4.01 (m, 3H), 3.90 (s, 3H), 3.85 (s, 3H),
.06 (q, J = 6.2Hz, 2H), 2.82 (t, J = 7.9Hz, 2H), 2.28
q, J = 6.6Hz, 2H), 2.12 (p, J = 7.8Hz, 2H) 1.89 (q,
(
2.2mL, 15.8mmol, 2.5equiv), and dimethylaminopyr-
idine (0.77g, 6.30mmol, 1equiv) in anhydrous dichloro-
methane was stirred at room temperature for 15min.
Propionyl chloride (1.1mL, 12.6mmol, 2equiv) was
slowly added and the mixture was stirred for 16h. The
reaction mixture was acidified with 1M HCl solution
and extracted with dichloromethane. The extracts were
dried over magnesium sulfate, filtered, and concentrated
by rotary evaporation to give a brown oil. The crude oil
was purified by column chromatography (2–5% metha-
nol/dichloromethane) to give 1.12g (48%) of a dipropi-
onylated product as a yellow oil.
1
3
J = 7.6Hz, 2H), 0.95 (t, J = 7.6Hz, 3H); C N MR
CDCl ) d 173.4, 158.8, 158.1, 147.7, 143.2, 133.9,
(
3
1
1
3
30.4, 128.4, 120.9, 118.8, 114.7, 114.2, 112.5, 112.0,
11.2, 110.2, 109.9, 109.2, 67.3, 56.5, 54.2, 46.5, 36.1,
2.2, 31.9, 30.8, 29.4, 10.4, 8.7. Anal. (C H N O Æ0.67
29 33
1
4
H O) C, H, N.
2
4.28. N-[2-((2-Phenyl)ethoxy)-7-methoxy fluorene-9-yl]
ethyl propanamide (2t)
1
Prepared from 2o and obtained as a viscous oil. H
A solution of the dipropionylated product (1.0g,
.72mmol) in methanol was saponified with 1Nsodium
2
NMR (CDCl ) d 7.47 (dd, J = 8.4, 3.0Hz, 2H), 7.25
3
hydroxide at room temperature. After 30min, the
reaction mixture was acidified with 1NHCl and
extracted into ethyl acetate. The extracts were dried over
magnesium sulfate, filtered, and concentrated by rotary
evaporation to give 0.78g (92%) obtained as a white
foam, mp 38–42ꢁC. IR (KBr) 3294, 1642, 1540, 1210,
(
4
m, 5H), 6.95 (m, 2H), 6.82 (dd, J = 8.4, 2.3Hz, 2H),
.82 (br, 1H), 4.15 (t, J = 7.2Hz, 2H), 3.90 (m, 1H),
.78 (s, 3H), 3.06 (t, J = 7.1Hz, 2H), 2.97 (q,
3
J = 6.2Hz, 2H), 2.24 (q, J = 6.5Hz, 2H), 1.80 (q,
1
3
J = 7.7Hz, 2H), 0.86 (t, J = 7.7Hz, 3H); C N MR
CDCl ) d 190.0, 173.4, 158.9, 158.1, 147.7, 138.3,
(
3
ꢀ
1
1
7
2
2
2
2
1
1
2
54cm
;
H NMR (CDCl ) d 7.50 (dd, J = 8.3,
3
134.1, 134.0, 129.1, 128.6, 126.6, 120.0, 113.8, 113.2,
11.0, 110.3, 69.2, 55.7, 45.8, 36.2, 36.0, 31.9, 29.5, 9.5;
.8Hz, 2H), 7.00 (m, 2H), 6.85 (dt, J = 8.4, 2.8Hz,
H), 5.01 (m, 1H), 3.94 (m, 1H), 3.84 (s, 3H), 3.07 (q,
H), 2.35 (m, 1H), 2.23 (m, 1H), 1.91 (q, J = 7.6Hz,
1
+
MS (ESI) MꢀH = 414. Anal. (C H NO Æ0.9H O)
2
7
29
3
2
C, H, N.
1
3
H), 2.24 (t, J = 7.6Hz, 3H); C NMR (CDCl ) d
3
74.5, 158.7, 155.8, 147.8, 147.5, 134.4, 133.1, 120.2,
19.8, 114.8, 112.9, 111.8, 110.3, 55.7, 45.5, 36.5, 31.7,
4.29. N-[2-(2-(3-Phenyl-1-propanoxy))-7-methoxy fluo-
rene-9-yl] ethyl propanamide (2u)
+
9.5, 9.6; MS (ESI) MꢀH = 310.1. Anal.
(
C H NO Æ0.5H O) C, H, N.
19 21 3 2
Prepared from 2o and obtained as a white solid, mp
1
1
06–109ꢁC. H NMR (CDCl ) d 7.47 (dd, J = 8.3,
3
4
.25. General procedure for alkylating 2o
2.7Hz, 2H), 7.15 (m, 5H), 6.95 (s, 2H), 6.81 (m, 2H),
.83 (br, 1H), 3.93 (m, 3H), 3.79 (s, 3H), 2.99 (q,
4
Acid chloride or alkylhalide (1equiv) was slowly added
to a suspension of 2o (1equiv) and potassium carbonate
J = 6.6Hz, 2H), 2.77 (t, J = 7.2Hz, 2H), 2.23 (q,
J = 6.7Hz, 2H), 2.04 (q, J = 6.4Hz, 2H), 1.86 (q,
J = 7.6Hz, 2H), 0.87 (t, J = 7.6Hz, 3H); C N MR
1
3
(
1equiv) in anhydrous acetonitrile at room temperature
and the suspension was stirred for 16h. The reaction was
quenched with water and extracted with dichlorometh-
ane. The organic extracts were dried over magnesium
sulfate, filtered, and concentrated by rotary evaporation
to give the products as oils (66–91%).
(CDCl ) d 193.2, 173.5, 158.843, 158.3, 147.8, 147.7,
3
141.6, 134.1, 134.0, 128.6, 128.5, 126.0, 120.0, 113.7,
113.2, 111.0, 110.3, 67.4, 55.7, 45.8, 36.2, 32.3, 31.9,
+
31.0, 29.5, 9.6; MS (ESI) MꢀH = 428. Anal.
(C H NO Æ0.5H O) C, H, N.
2
8
31
3
2

4610
J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4.30. [[7-Methoxy-9-[2-[(1-oxopropyl)amino]ethyl]-9H-
fluoren-2-yl]oxy]acetic acid,methyl ester (2y)
114.4, 111.9, 111.6, 45.6, 36.0, 31.8, 24.4, 9.5; MS
+
(ESI) MꢀH = 300. Anal. (C H F NO ) C, H, N .
1
8
17
3
3
Prepared from 2o and obtained as an off-white solid, mp
1
9
7
4
3
1–94ꢁC. H NMR (CDCl ) d 7.53 (d, J = 8.3Hz, 2H),
3
References and notes
.03 (dd, J = 7.9, 2.2Hz, 2H), 6.86 (d, J = 8.4Hz, 2H),
.91 (br, 1H), 4.66 (s, 2H), 3.97 (t, J = 5.4Hz, 1H),
.80 (s, 3H), 3.76 (s, 3H), 3.03 (q, J = 7.2Hz, 2H), 2.29
1
. (a) Cassone, V. M. Effects of Melatonin on Vertabrate
Circadian Systems. Trends Neurosci. 1990, 13, 457–464;
(
q, J = 6.1Hz, 2H), 1.89 (q, J = 7.6Hz, 2H), 0.86 (t,
(
b) Reppert, S. M.; Weaver, D. R. Coordination of
Circadian Timing in Mammals. Nature 2002, 418(6901),
35–941.
13
J = 7.6Hz, 3H); C NMR (CDCl ) d 173.6, 169.5,
3
1
1
3
58.1, 157.0, 147.9, 147.8, 135.2, 133.7, 120.2, 120.0,
13.7, 113.3, 111.4, 110.2, 65.8, 55.6, 52.3, 45.7, 36.2,
9
2. (a) Goldman, B. D.; Darrow, J. M. The Pineal Gland and
Mammalian Photoperiodism. Neuroendocrinology 1983,
37, 386–396; (b) Benloucif, S.; Dubokovich, M. L.
Melatonin and Light Induce Phase Shifts of Circadian
Rhythms in the C3H/HeNMouse. J. Biol. Rhythms 1996,
+
2.0, 29.5, 9.6; MS (ESI) MꢀH = 382. Anal.
(
C H NO Æ0.5H O) C, H, N.
22 25 5 2
4.31. [[7-Methoxy-9-[2-[(1-oxopropyl)amino]ethyl]-9H-
fluoren-2-yl]oxy]acetic acid (2z)
1
1, 113–125.
3
4
. Reviewed in Arendt, J. Melatonin and the Mammalian
Pineal Gland; Chapman and Hall: London, 1995.
. Reppert, S. M.; Weaver, K. R.; Godson, C. Melatonin
Receptors Step into the Light: Cloning and Identification
of Subtypes. Trends Pharmacol. 1996, 17, 100–102.
Ester 2y (0.22g, 0.57mmol) was dissolved in methanol at
room temperature. Sodium hydroxide (as a 1Nsolution
in water, 0.6mL, 0.57mmol) was added, then the mix-
ture was stirred for 8h. The reaction mixture was acidi-
fied with 1M HCl solution, then extracted with
dichloromethane. The organic layer was dried over mag-
nesium sulfate, filtered, and concentrated to give 0.17g
5. Formerly the mel1a and mel1b receptors, see: Dubowkov-
ich, M. L.; Cardinali, D. P.; Delagrange, P.; Krause, D.
N.; Strosberg, A. D.; Sugden, D.; Yocca, F. D. The
IUPHAR Compendium of Receptor Characterization and
Classification; IUPHAR media: London, 1995; pp 271–
277.
. (a) Reppert, S. M.; Weaver, D. R.; Ebisawa, T. Cloning
and Characterization of a Mammalian Melatonin Recep-
tor that Mediates Reproductive and Circadian Responses.
Neuron 1994, 13, 1177–1185; (b) Reppert, S. M.; Godson,
C.; Mahle, C. D.; Weaver, D. R.; Slaugenhaupt, S. A.;
Gusella, J. F. Molecular Characterization of a Second
Melatonin Receptor Expressed in Human Retina and
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1995, 92, 8734–8738.
7. Reppert, S. M.; Weaver, D. R. Coordination of Circadian
Timing in Mammals. Nature 2002, 418, 935–941.
. (a) Liu, C.; Weaver, D. M.; Jin, X.; Shearman, L. P.;
Pieschl, R. L.; Gribkoff, V. K.; Reppert, S. M. Molecular
Dissection of Two Distinct Actions of Melatonin on the
Suprachiasmatic Circadian Clock. Neuron 1997, 19,
of an off-white solid (81%) obtained as an off-white so-
1
lid, mp 55–59ꢁC. H NMR (CDCl ) d 8.82 (br, 1H),
7
6
5
3
6
.50 (dd, J = 8.3, 4.9Hz, 2H), 7.02 (d, J = 2.1Hz, 1H),
.97 (d, J = 2.1Hz, 1H), 6.84 (dt, J = 8.3, 2.3Hz, 2H),
.12 (t, J = 5.6Hz, 1H), 4.65 (s, 2H), 3.89 (t,
J = 4.9Hz, 1H), 3.81 (s, 3H), 2.97 (q, J = 6.5Hz, 2H),
.19 (m, 2H), 1.96 (q, J = 7.7Hz, 2H), 0.91 (t,
2
13
J = 7.7Hz, 3H); C NMR (CDCl ) d 174.9, 171.3,
3
1
1
2
59.0, 156.9, 147.7, 147.6, 134.8, 133.9, 120.2, 120.1,
14.8, 113.1, 110.5, 110.2, 65.6, 55.7, 45.5, 36.4, 31.6,
+
9.4, 9.6; MS (ESI) MꢀH = 368. Anal. (C H NO Æ1-
2
1
23
5
H O) C, H, N.
2
8
4.32. N-2-(2-Methoxy-7-fluorofluoren-9-yl)ethyl propan-
amide (2aa)
9
M.; Benloucif, S.; Masana, M. I. Selective MT Melatonin
Receptor Antagonists Block Melatonin-Mediated Phase
Advances of Circadian Rhythms. FASEB J. 1998, 12,
1–102; (b) Dubokovich, M. L.; Yun, K.; Al-Ghoul, W.
Prepared in an analogous fashion to 2b and obtained as
a white solid, mp 72–73ꢁC. IR (film) 1644, 1558,
2
ꢀ
1
1
1
230cm
;
.15 (dd J = 8.6, 1.7Hz, 1H), 7.06–7.00 (m, 2H), 6.91
H NMR (CDCl ) d 7.59–7.54 (m, 2H),
3
1
211–1220.
7
9
. (a) Mahle, C. D.; Watson, A. J. Melatonin Receptors:
Potential Targets for Central Nervous System Disorders.
Exp. Opin. Invest. Drugs 1997, 6, 399–406; (b) Li, P.-K.;
Witt-Enderby, P. A. Melatonin Receptors as Potential
Targets for Drug Discovery. Drugs Fut. 2000, 25, 945–957.
0. (a) Petrie, K.; Conaglen, J. V.; Thompson, L.; Chamber-
lain, K. Effect of Melatonin on Jet Lag After Long Haul
Flights. Br. Med. J. 1989, 298, 705–707; (b) Arendt, J.
Melatonin in Humans: Jet-Lag and After. Adv. Pineal Res.
1991, 5, 299–302.
1. Sack, R. L.; Blood, M. L.; Lewy, A. J. Melatonin
Rhythms in Night Shift Workers. Sleep 1992, 15, 434–441.
2. Rosenthal, N. E.; Sack, D. A.; Jacobsen, F. M.; James, S.
P.; Parry, B. L.; Arendt, J.; Tamarkin, L.; Wehr, T. A.
Melatonin in Seasonal Affective Disorder and Photother-
apy. J. Neural. Transm. Suppl. 1986, 21, 257–267.
3. (a) Wehr, T. A. The Durations of Human Melatonin
Secretion and Sleep Respond to Changes in Daylength
(Photoperiod). J. Clin. Endocrinol. Metab. 1991, 73,
1276–1280; (b) Oldani, A.; Ferini-Strambi, L.; Zucconi,
(
dd J = 8.3, 2.3Hz, 1H), 4.94 (br s, 1H), 4.03–3.99 (m,
1
2
H), 3.85 (s, 3H), 3.08–3.02 (m, 2H), 2.33–2.26 (m,
H), 1.42 (q J = 7.6Hz, 2H), 0.98 (t, J = 7.6Hz, 3H);
1
3
C NMR (CDCl ) d 120.3, 119.4, 119.8, 114.3, 114.0,
3
1
13, 2, 111.6, 111.3, 109.9, 55.4, 45.5, 35.9, 31.7, 29.3,
1
+
9
H, N.
.3; MS (ESI) MꢀH = 312. Anal. (C H FNO ) C,
1
9
20
2
4
(
.33. N-[2-(2,7-Difluorofluoren-9-yl)ethyl]-propanamide
2bb)
1
1
Prepared in an analogous fashion to 2b and obtained as
a white solid, mp 125–126ꢁC. IR (film) 1642, 1554,
ꢀ
220cm ; H NMR (CDCl ) d 7.62–7.58 (m, 2H),
3
1
1
1
7
4
2
.22–7.18 (m, 2H), 7.08–7.02 (m, 2H), 5.00 (br s, 1H),
.01–4.00 (m, 1H), 3.06–2.99 (m, 2H), 2.30–2.24 (m,
H), 1.94 (q, J = 7.6Hz, 2H), 0.98 (t, J = 7.5Hz, 3H);
1
1
3
C NMR (CDCl ) d 173.5, 136.1, 120.7, 120.6, 114.7,
3

J. R. Epperson et al. / Bioorg. Med. Chem. 12 (2004) 4601–4611
4611
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18. Prepared from the acid by Fischer esterification. The acid
failed to undergo Suzuki coupling.
19. Wadsworth, W. S.; Emmons, W. D. The Utility of
Phosphonate Carbanions in Olefin Synthesis. J. Am.
Chem. Soc. 1961, 83, 1733.
1
4. Zhdanova, I. V.; Wurtman, R. J.; Regan, M. M.; Taylor,
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Age-Related Insomnia. J. Clin. Endocrin. Met. 2001,
8
6(10), 4727–4730.
1
1
5. Weaver, D. R.; Reppert, S. M. The Mel1a Melatonin
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Dissection of Two Distinct Actions of Melatonin on the
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21. Prepared in three steps from methyl 3-hydroxy-5-bromo-
benzoate by coupling with 4-methoxyphenylboronic acid
followed by hydrolysis and acetylation.
22. Mattson, R. J.; Catt, J. D.; Keavy, D.; Sloan, C. P.;
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9
1–102; (b) Nonno, R.; Pannacci, M.; Lucini, V.; Angeloni,
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2
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1
13(6), 1199–1202.
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1
7. For a review see: Suzuki, A. Recent Advances in the
Cross-Coupling Reactions of Organoboron Derivatives