Synthesis of new benzoxazinone derivatives as neuropeptide Y5 antagonists for the treatment of obesity

Article abstract of DOI:10.1021/jm049599u

Screening of our internal chemical collection against the neuropeptide Y5 (NPY Y5) receptor allowed the identification of a benzoxazine derivative 5f as a hit that showed moderate affinity (IC₅₀ = 300 nM). With the aim of improving the in vitro potency, a series of 2-benzoxazinone derivatives have been synthesized and tested for NPY Y5 activity. Most of the compounds were found to be potent and selective NPY Y5 antagonists having nanomolar binding affinities for the NPY Y5 receptor and showing functional antagonism in the forskolin-induced cyclic AMP test. Prelimminary studies in order to understand the structure-activity relationship were undertaken. Selected compounds were further evaluated for in vivo efficacy, affording the lead compound 2-[4-(8-methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-yl] -N-(9-oxo-9H-fluoren-3-yl)acetamide 5p, which displayed in vivo activity reducing food intake in rodents.

Full text of DOI:10.1021/jm049599u

2080
J. Med. Chem. 2005, 48, 2080-2092
Synthesis of New Benzoxazinone Derivatives as Neuropeptide Y5 Antagonists
for the Treatment of Obesity#
Antoni Torrens,*,† Josep Mas,† Adriana Port,† Jose´ Aurelio Castrillo,† Olga Sanfeliu,† Xavier Guitart,‡
Alberto Dordal,‡ Gonzalo Romero,‡ Ma Angeles Fisas,‡ Elisabeth Sa´nchez,‡ Enrique Herna´ndez,‡ Pilar Pe´rez,‡
Raquel Pe´rez,‡ and Helmut Buschmann§
Departments of Discovery Chemistry and Discovery Biology, Laboratorios Dr. Esteve, S.A., Av. Mare de De´u de Montserrat 221,
08041 Barcelona, Spain
Received May 28, 2004
Screening of our internal chemical collection against the neuropeptide Y5 (NPY Y5) receptor
allowed the identification of a benzoxazine derivative 5f as a hit that showed moderate affinity
(IC50 ) 300 nM). With the aim of improving the in vitro potency, a series of 2-benzoxazinone
derivatives have been synthesized and tested for NPY Y5 activity. Most of the compounds were
found to be potent and selective NPY Y5 antagonists having nanomolar binding affinities for
the NPY Y5 receptor and showing functional antagonism in the forskolin-induced cyclic AMP
test. Prelimminary studies in order to understand the structure-activity relationship were
undertaken. Selected compounds were further evaluated for in vivo efficacy, affording the lead
compound 2-[4-(8-methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-yl]-N-(9-oxo-9H-fluoren-
3-yl)acetamide 5p, which displayed in vivo activity reducing food intake in rodents.
Introduction
expressed in several species except for the y6 subtype,
which has been shown to be expressed in mouse and
rabbit but not in rat and primates. On the other hand,
the subtype Y3 has not yet been cloned and its real
existence still remains to be fully established. NPY Y1
and NPY Y5 receptors have been recognized as strong
candidates for the mediation of NPY in food intake.17,18
The involvement of NPY Y5 has been suggested by
pharmacological results on feeding in rodents,38-45 by
the inhibitory effects of NPY Y5 receptor antisense
oligonucleotides, and by using NPY Y5 antagonists.
On the basis of all these data and having as a
hypothesis that an agent with antistarvation properties
would be valuable to control food intake, many groups
have postulated different and selective NPY Y5 antago-
nists (Chart 1) as potential drugs for the treatment of
obesity.46a-f Since in vivo specificity of those compounds
is unclear, additional structurally diverse NPY Y5
antagonists are important in order to probe the role of
NPY Y5 receptor.
Pharmacological research in appetite control has been
a hot field during the past decade because obesity is
recognized as a fast growing and spreading disease.
Obesity and related diseases such as type II diabetes
are clearly escalating not only in the U.S. but also in
many other countries.1,2 Neuropeptide Y (NPY) is a 36
amino acid peptide originally discovered in extracts of
porcine brain.3 The peptide belonging to a broad family
of peptides (which includes peptide YY and pancreatic
polypeptide) has a wide distribution in the central4-6
and peripheral nervous system.7-9
Neuropeptide Y has a number of physiological effects,
and on the basis of experimental studies in primates
and rodents, it has repeatedly been suggested that there
is a relationship of NPY and its receptors with several
pathological disorders including depression, anxiety-
related disorders, seizures in epilepsy, and potentiation
of vasoconstriction.10-16 NPY is expressed in hypotha-
lamic regions thought to be important in the regulation
of feeding, its expression is sensitive to energy status,
while its administration reduces energy expenditure,17,18
and one of the most profound ability of NPY is to acutely
stimulate feeding.19-22 Although this body of results has
led to the recognition of NPY as a key regulator of food
intake, the real implication of the peptide is still
controversial,23,24 and targeted gene deletion of NPY
provides limited evidence to support this idea.25,26
The biological effects of NPY are mediated through
its interaction with at least five different cloned recep-
tors known as the Y1, Y2, Y4, Y5, and y6 subtypes.27-30
All these receptors have been cloned31-37 and are
In the present study, we focus on the preparation of
non-peptide antagonists to the NPY Y5 receptor as part
of our antiobesity program, and we report the discovery
of a novel benzoxazinone class of NPY Y5 antagonists.47
Chemistry
As a result of the screening of the NPY Y5 receptor
performed with our internal compound collection, benz-
oxazinone 5f (Chart 2) was identified as a hit displaying
moderate binding affinity (IC50 ) 300 nM). Compound
5f provided us with a lead for further optimization that
had common structural features with benzimidazolone
derivatives described by Bayer46f (Chart 1). In this
report, we describe the synthesis and biological activity
of analogues of 5f and report our preliminary SAR
studies that were undertaken in an effort to improve
the in vitro potency of this series.
# Dedicated to the memory of Paul Janssen.
* To whom correspondence should be addressed. Phone +34
934466270. Fax: +34 934501611. Email: atorrens@esteve.es.
† Department of Discovery Chemistry.
‡ Department of Discovery Biology.
§ Head of Research.
10.1021/jm049599u CCC: $30.25 © 2005 American Chemical Society
Published on Web 10/30/2004

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2081
Chart 1. Examples of NPY Y5 Receptor Antagonists
Chart 2. General Structure of Benzoxazinone Series
employing LiAlH4 as reducing agent in THF. The
procedure proved to be very efficient, in most cases
affording the amino alcohols 2a-c in excellent yields.
In addition, the efficiency of this method allowed the
reactions to be performed in parallel on scales ranging
from 5 to 10 g of the starting materials. In most cases
the crude products were sufficiently pure and were used
in next step without further purification. On the
other hand, amino alcohols 2d-g are commercially
available.
A reductive amination reaction on compounds 2a-g
was carried out to introduce the piperidine moiety
(Scheme 1). Initial condensation of the amino alcohols
with the N-Boc-4-piperidone and subsequent reduction
of the generated imino functionality with NaBH3CN
under acidic conditions generally afforded the products
3a-g in good yields.
Scheme 1a
The benzoxazinone ring system 4 is formed via
carbonylative cyclization of intermediates 3. This pro-
cess (Scheme 1) was performed in parallel using triphos-
gene as the CO equivalent. It was found that the
efficiency of this reaction depended very much on the
nature of the ring substituents. Although the expected
products were formed in most cases, the yields were
moderate and the reaction mixtures were often very
complex, requiring further purification by column chro-
matography or by recrystallization.
Removal of the Boc protecting group was performed
by slow addition of acetyl chloride to a solution of
piperidine derivatives 4a-g in methanol or by treat-
ment with hydrochloric acid in ethanol or diethyl ether
(Scheme 1). As expected, these reactions are easily
performed in parallel and afforded the products as
hydrochloride salts in high yields and purity.
Chloroacetamide derivatives were required for the
preparation of the final targets. These compounds have
been prepared using the general procedure described
in the experimental part. Essentially, chloroacetyl
chloride was reacted with a selection of amines to yield
the desired alkylating agents (Chart 3). Most of the
amines required for the preparation of compounds 8-24
are commercially available. The amines that are not
commercially available were prepared following litera-
ture procedures (see experimental part).
a Reagents: (i) LiAlH4/THF; (ii) N-Boc-4-piperidone, NaBH3CN;
(iii) (a) triphosgene, (b) HCl.
We were interested in targets in which the benzox-
azinone ring and the amide moiety are varied to explore
the effect of these substituents on the affinity. The
diversity of the benzoxazinone ring (R1-R3) is intro-
duced at the beginning of the synthetic pathway.
Further diversification then focuses on the amide moiety
(Ar), which is introduced in the final step. Several
anthranilic acids 1a-c, with the appropriate substitu-
tion patterns, were chosen as starting materials to
investigate the effect of the benzoxazinone substituents
on the binding and functionality properties. The diver-
sity of the amide moiety was achieved by introduction
of selected arylamines, which in some cases need to be
previously synthesized.
The preparation of the benzoxazinone scaffold (Scheme
1) started with reduction of commercial anthranilic
acids 1a-c to the corresponding alcohols 2. The trans-
formation was performed under standard conditions

2082 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6
Chart 3. Chloroacetamides 8-24
Torrens et al.
Scheme 2. Synthesis of Compounds 5a-z and a-ma
Scheme 3. Synthesis of Compounds 7a-ca
a Reagents: (i) ArNHCOCH2Cl, DMF, K2CO3.
a Reagents: (i) NaBH4, EtOH.
Reaction conditions were tested for the alkylation
step. The conditions that proved to be the most efficient
and most suitable for performing the alkylation reac-
tions in parallel employed K2CO3 as a base and DMF
as a solvent (Scheme 2). All products were purified by
parallel chromatography or were transformed further
to HCl salts and recrystallized. The structures of
compounds 5a-z and 6a-m synthesized by this pro-
cedure are depicted in Table 1.
To obtain the hydroxy derivatives 7a-c, an additional
step was carried out. The reduction of the keto group of
compounds 5o-q was performed with NaBH4 under
standard conditions, affording the desired final products
with excellent yields (Scheme 3).
antagonists was studied in an in vitro system using C6
cells overexpressing the receptor. The NPY Y5 receptor
is known to be negatively coupled to the adenylyl cyclase
system, so agonists of the receptor would decrease in a
significant way the levels of intracellular cyclic AMP
(cAMP). As depicted in Figure 1, our compounds clearly
showed antagonistic activity because they were able to
reverse the effect of PYY on cyclic AMP levels. The
binding affinity for the NPY Y5 receptor and functional-
ity results of selected compounds are illustrated in Table
1.
In discussing the initial SAR within the series, we
have divided the structure into two main parts: the
amide moiety (Ar) and the substitution (R1, R2, R3) in
the benzoxazinone scaffold (Table 1). With the aim of
enhancing affinity, initial efforts were focused on the
modification of the p-chloroaniline group present in 5f.
Diverse simple monocyclic anilines were used in the first
approach. Removing the p-chloro group as in 6k, using
aniline itself, led to a dramatic loss of activity. Among
all the substituted anilines used, p-cyano (6i, IC50 ) 132
nM) and mainly p-acetyl (6a, IC50 ) 17.3 nM) groups
afforded the highest affinities. It seemed that the
presence of a carbonyl group could be important. To
explore this hypothesis, we introduced several groups
containing this function in a different position of the
phenyl ring with disappointing results (i.e., a 2-COOMe
ester group 5w, IC50 > 1000 nM). We then examined
Results and Discussion
Screening of our internal chemical collection against
the NPY Y5 receptor resulted in the identification of
the novel benzoxazinone class lead 5f. This lead had an
IC50 value of 300 nM and obviously needed to be further
optimized in terms of potency. For this purpose, an
exploratory library using parallel synthesis was pre-
pared.47 In this report we describe the preparation and
biological results of selected compounds from this library
and our understanding of the structure-activity rela-
tionship.
The binding affinities at the NPY Y5 receptor were
determined in a filter binding assay using [125I]-PYY.
The activity of the compounds as putative agonists or

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2083
Table 1. NPY5 Binding Affinity and Functional Inhibition of the NPY Y5 Agonist Induced CAMP Accumulationa
b
125
a Table shows the effect of compounds 5a-z, 6a-m, and 7a-c.
[
I]-PYY binding to the rat NPY Y5 receptor. c Reversal of PYY
inhibition of forskolin-stimulated cyclic AMP production. n.d.: not determined.
the introduction of a second phenyl ring attached to the
4-carbonyl group, with excellent results (i.e., 6l, IC50
7.6 nM). Interestingly, the same substitution pattern
in position 2 failed to give activity (i.e., 6d, IC50 > 1000
)

2084 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6
Torrens et al.
Figure 2. Acute feeding effects of compound 5p, a NPY Y5
receptor antagonist. Wistar rats were food-deprived for 24 h.
Vehicle or 5p were intraperitoneally administered, and food
intake was measured 1, 2, 4, and 6 h after the administrations.
Open bars show food intake in vehicle-treated animals, and
filled bars show food intake in compound-treated animals at
a dose of 10 mg/kg. Bars show the mean ( SEM: (/) P < 0.05,
n ) 10-12 for each group.
Figure 1. Functional activity of selected compounds. The
antagonistic properties of these compounds were demonstrated
by their ability to reverse the inhibitory effects of PYY on the
forskolin-stimulated cyclic AMP formation in C6 cells stably
expressing the rat NPY Y5 receptor. Bars express the mean
( SEM of the percentage of cyclic AMP formation in the
presence of PYY compared to controls (forskolin-stimulated
cyclic AMP formation in C6 cells in the absence of PYY).
Experiments were performed at least three times in separate
experiments.
comparison of 5a and 5b could suggest that H is better
for affinity, but on the other hand, looking to 5r and 5s
could lead to the conclusion that Me is preferred. The
same could be applied to position R3 comparing Me and
H. While pairs of compounds 5e and 5f and 5p and 5o
seem to demonstrate that H at R3 leads to more active
products, the differences between 7b and 7c indicate
the opposite. Therefore, substitution in this part of the
molecule is tolerated, but no clear correlation between
the presence of a particular group and the binding
affinity could be established.
Selected compounds with high affinity were profiled
in a commercially available panel of more than 50
radioligand binding assays (MSD, Taiwan). These com-
prise the characterization of potential interactions at
the ligand binding site of a wide range of mainly
G-protein-coupled receptors (GPCRs) and ligand-gated
ion channels, plus a limited number of modulatory sites
on voltage-gated ion channels. Binding results showed
a marked selectivity of our compounds for the NPY Y5
receptor with respect to other NPY receptors (NPY Y1,
NPY Y2), and only a certain degree of affinity for the
5-HT2 receptor, the monoamine transporter, and for the
sodium channel site 2 was observed, determined at 10
µM.
The antagonistic nature of the compounds is shown
in Figure 1, and their ability to reverse the effect of the
NPY Y5 receptor agonist PYY on cyclic AMP levels in
an in vitro cell system was clearly established.
The in vivo activity of the compounds on food intake
in rats was studied in animals that fasted for 24 h and
then allowed to eat with no restrictions. Figure 2 shows
the profile of one the compounds with antagonistic
activity at the NPY Y5 receptor on food consumption in
fasted rats. Among several compounds tested, 5p, when
administered intraperitoneally, clearly reduced food
intake after a fasting period, and the effect lasts for at
least 6 h.
Compound 5p clearly shows hypophagic capacities in
a rat model. Although it does not have the highest
affinity for the NPY Y5 receptor, its demonstrated
antagonistic properties and its excellent behavior in in
vivo tests make 5p a potential candidate for profiling.
Further studies in order to establish its metabolic and
nM), suggesting that the substitution in position 4 is
necessary for the affinity. With these results in our
hands, we turned our attention to structurally related
arylamines used by others in the NPY Y5 described
antagonists. Thus, incorporation of 3-aminofluorenone46f
gave 5o (IC50 ) 23.3 nM), 5p (IC50 ) 50 nM), and 5q
(IC50 ) 25 nM), which could be considered constrained
analogues of 6l, 5u, and 5v, respectively. It is noted that
2-amino and 4-aminofluorenone groups failed to provide
affinity. This fact can be observed by comparing com-
pound 5o (IC50 ) 23.3 nM) with 5r (IC50 >1000 nM)
and 6m (IC50 ) 138.2 nM). On the other hand, introduc-
tion of 3-amino-9-ethylcarbazole46e (i.e., 5l, IC50 ) 50
nM) and 4-phenyloxyaniline46b (i.e., 5a, IC50 ) 20 nM)
afforded in both cases compounds with remarkable
affinities. To study the influence of the carbonyl function
of fluorenone derivative 5o, we prepared the corre-
sponding hydroxyl group by NaBH4 reduction. Surpris-
ingly, 7b showed higher potency (IC50 ) 8.7 nM) than
the parent compound. The analysis of these data could
suggest that the presence of the carbonyl is not essential
for affinity. To determine the influence of the hydroxyl
group, the preparation of new compounds in a lead
optimization process is currently ongoing.
With this set of data, we focused our efforts to study
the influence of different substituents in the benzox-
azinone phenyl ring. After preparation of several mono-
substituted analogues with R1 ) H, Cl or R2 ) H, Cl,
Me, F, or R3 ) H, Me, MeO, some differences in terms
of binding results could be observed. Thus, we tried to
determine the role of these substituents by studying
pairs of compounds with a single substitution change
at R1 or R2 or R3. On the basis of the results displayed
in Table 1, in the case of R2 being Cl or H, a comparison
between compounds 5r and 5t and also between 5h and
5g showed a preference for Cl substitution, whereas a
comparison between 5c and 5a showed a preference for
H. Similar results were obtained when we studied pairs
of compounds with Me or H at R2. As an example, a

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2085
triturated with ether and vacuum-dried, giving the title
compound as a yellow solid (mp 76-78 °C; 10.33 g, 82%). IR
(KBr) 3389, 1601, 1578, 1451, 1399, 1244, 1004, 780 cm-1. 1H
NMR (300 MHz, DMSO-d6) δ ppm 4.63 (d, J ) 5.42 Hz, 2 H),
5.09 (t, J ) 5.42 Hz, 1 H), 5.40 (s, 2 H), 6.65 (m, 2 H), 7.02 (t,
J ) 7.98 Hz, 1 H).
pharmacokinetic characteristics are currently ongoing.
Future results should help the optimization of our series
and to throw some more light on the controversial
subject of the real implication of the NPY Y5 receptor
in feeding behavior.
2-Amino-5-fluorobenzyl Alcohol (2b). Following the
procedure described for the synthesis of 2a, compound 2b was
prepared from commercial 2-amino-5-fluorobenzoic acid (1b)
(21.98 g, 142 mmol) to give a brown solid (mp 103-108 °C;
14.60 g, 73%). IR (KBr) 3385, 1508, 1430, 1251, 1017, 882, 821
Conclusion
Because the physiological role of the NPY Y5 receptor
still remains unclear, the evaluation of structurally
diverse new classes of compounds could be critical to
address the real importance of the Y5 receptor in food
intake related diseases.
We have synthesized a novel series of benzoxazinone
derivatives that have been identified as highly potent
and selective Y5 antagonists. Initial studies of the
structure-activity relationship looking at the effect of
benzoxazinone phenyl ring substitution have shown that
introduction of a methyl or a halogen group is tolerated
but not relevant for affinity. On the other hand,
incorporation of several arylamine groups in the other
part of the structure has led to the conclusion that
3-aminofluorenone and the corresponding hydroxy de-
rivatives are preferred.
The new prepared compounds should prove useful for
further pharmacological characterization of the role of
the NPY Y5 receptor. Although compound 5p does not
display the highest affinity and although more phar-
macological studies are needed on its convenient an-
tagonistic profile and its remarkable activity in acute
feeding tests, 2-[4-(8-methyl-2-oxo-4H-benzo[d][1,3]ox-
azin-1-yl)piperidin-1-yl]-N-(9-oxo-9H-fluoren-3-yl)acet-
amide hydrochloride (5p) could be considered as a
potential drug candidate for the treatment of obesity.
1
cm-1. H NMR (300 MHz, DMSO-d6) δ ppm 4.32 (d, J ) 5.42
Hz, 2 H), 4.73 (s, 2 H), 5.11 (t, J ) 5.42 Hz, 1 H), 6.56 (dd, J
) 8.64, 4.98 Hz, 1 H), 6.75 (td, J ) 8.64, 3.08 Hz, 1 H), 6.89
(dd, J ) 9.81, 3.08 Hz, 1 H).
2-Amino-3-methoxybenzyl Alcohol (2c). Following the
procedure described for the synthesis of 2a, compound 2c was
prepared from commercial 2-amino-3-methoxybenzoic acid (1c)
(15.13 g, 90 mmol) to give a brown solid (mp 42-46 °C; 12.1
g, 88%). IR (KBr) 3398, 1483, 1442, 1278, 1238, 1022, 740 cm-1
.
1H NMR (300 MHz, DMSO-d6) δ ppm 3.74 (s, 3 H), 4.38 (d, J
) 5.42 Hz, 2 H), 4.50 (s, 2 H), 5.00 (t, J ) 5.42 Hz, 1 H), 6.51
(t, J ) 7.76 Hz, 1 H), 6.72 (m, 2 H).
General Procedure for the Synthesis of Substituted
1-Piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-ones
(4a-g). 1-Piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-ones
(4a-g) were synthesized, as shown in Scheme 1, according to
the method described by Ian M. Bell et al.49 by reductive
amination of 2-aminobenzyl alcohols (2a-g) treated with
N-(tert-butyloxycarbonyl)-4-piperidone and NaBH3CN, fol-
lowed by cyclization using triphosgene and final elimination
of the protective group by treatment in acidic media.
6-Chloro-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4g). A solution of 1-(tert-
butyloxycarbonyl)-4-piperidone (9.96 g, 50 mmol), 2-amino-5-
chlorobenzyl alcohol (8.66 g, 55 mmol), and acetic acid (6.3 mL,
110 mmol) in dry toluene (200 mL) was refluxed with azeo-
tropic removal of water for 6 h, then cooled at room temper-
ature and concentrated under reduced pressure to about one-
half of the original volume. To the solution were added
NaBH3CN (10.37 g, 165 mmol) and dry THF (150 mL). Acetic
acid (4.9 mL, 85 mmol) was then added dropwise. The reaction
mixture was stirred at room temperature for 24 h. The reaction
mixture was concentrated under reduced pressure, and the
residue was dissolved in EtOAc (350 mL). The EtOAc layer
was washed with saturated aqueous NaHCO3 (4 × 125 mL)
and brine (125 mL). The EtOAc layer was dried (Na2SO4) and
filtered, and the solvent was removed under reduced pressure.
The residue was purified by flash chromatography using 30%
EtOAc in hexanes, affording 1-(tert-butyloxycarbonyl)-4-[4-
chloro-(2-hidroxymethylphenylamine)]piperidine (3g) as a syrup
Experimental Section
General Methods. Melting points were determined in open
capillary tubes on a Bu¨chi 535 melting point apparatus and
are uncorrected. Proton NMR spectra were obtained on a
Varian Unity 300 (300 MHz) spectrometer. Elemental analysis
for carbon, hydrogen, and nitrogen for target compounds were
carried out by Serveis Cientificote`cnics of Parc Cient´ıfic of
Barcelona (PCB). HPLC analysis was performed using Agilent
1100 (software Chemstation A.06.03) equipment with a Waters
XTerra MS C8 3.9 mm × 150 mm, 5 µm column, eluting with
a mixture of acetonitrile containing 0.05% TFA and water
containing 0.05% TFA. HPLC/MS analyses were recorded on
a ThermoFinnigan instrument equipped with a Surveyor
pump, a Waters XTerra MS C18 4.6 mm × 50 mm, 5 µm
column and a LCQ DECA XP ion trap analyzer working in
positive atmospheric pressure chemical ionization (ApcI).
Eluents were 10 mM ammonium acetate and acetonitrile.
Analytical thin-layer chromatography (TLC) was conducted on
precoated silica gel 60 F254 plates (Merck). Chromatography
was conducted on silica gel 60, 220-400 mesh. All starting
materials were obtained from commercial sources and used
as received.
1
(16.30 g, 96%). H NMR (CDCI3) δ ppm 1.32 (d, J ) 11.2 Hz,
2H), 1.41 (s, 9H), 1.92 (d, J ) 11.2 Hz, 2H), 2.92 (t, J ) 12.0
Hz, 1H), 3.10 (s, 1H), 3.37 (m, 1H), 3.88 (d, J ) 13.7 Hz, 2H),
4.49 (s, 2H), 4.75 (s, 1H), 6.52 (d, J ) 8.6 Hz, 1H), 6.96 (s,
1H), 7.07 (d, J ) 8.6 Hz, 1H).
This intermediate 3g (13.50 g, 39.5 mmol) was dissolved in
dry THF (150 mL) and cooled to 0 °C. To the solution were
added N,N-diisopropylethylamine (21.5 mL, 125 mmol) and
triphosgene (4.35 g, 14.6 mmol). The reaction mixture was
stirred at 0 °C for 1 h and then at room temperature for 72 h.
Diethyl ether (150 mL) was added, the mixture was cooled to
0 °C for 2 h, and the hydrochloride salt of DIEA was removed
by filtration. The solvents were removed under reduced
pressure, and the residue was dissolved in EtOAc (300 mL).
The EtOAc solution was washed with 5% aqueous citric acid
(2 × 250 mL), water (100 mL), and saturated aqueous NaHCO3
(2 × 200 mL). The EtOAc layer was dried (Na2SO4) and
filtered, and the solvent was removed under reduced pressure.
The residue was crystallized from boiling diethyl ether to
afford 1-(tert-butyloxycarbonyl)-4-(piperidinyl)-6-chloro-1,4-
dihydrobenz[d][1,3]oxazin-2-one 4d as a white solid (mp 177-
The aminobenzyl alcohols 2d-g were obtained from com-
mercial suppliers.
Chemistry Methods. 2-Amino-6-chlorobenzyl Alcohol
(2a). Under a nitrogen atmosphere, a solution of commercial
2-amino-6-chlorobenzoic acid 1a (13.72 g, 80 mmol) in dry THF
(100 mL) was added dropwise to a 1 M solution of LiAlH4 in
THF (160 mL) while the temperature was maintained at 0 °C.
The resulting mixture was allowed to reach room temperature
and was stirred for 2 h. The mixture was hydrolyzed by
addition of water (6.5 mL) and 5% NaOH (20 mL). The
resulting suspension was filtered; the precipitate was washed
with ethyl acetate, washed once with water and brine, dried
over Na2SO4, filtered, and evaporated. The residue was
1
179 °C; 14.45 g, 67%). H NMR (CDCI3) δ ppm 1.46 (s, 9H),
1.79 (d, J ) 10.1 Hz, 1H), 2.54 (m, 2H), 2.78 (m, 2H), 3.96 (m,

2086 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6
Torrens et al.
1H), 4.28 (m, 2H), 5.02 (s, 2H), 6.98 (d, J ) 8.7 Hz, 1H), 7.13
(d, J ) 2.4 Hz, 1H), 7.28 (dd, J ) 8.7 Hz, 2.4 Hz, 1H).
H), 5.06 (s, 2 H), 7.11 (m, 2 H), 7.23 (dd, J ) 7.25, 1.39 Hz, 1
H), 8.50 (s, 1 H), 9.48 (s, 1 H).
General Procedure for the Synthesis of N-Chloroacet-
amides (8-24). The chloroacetamides were obtained from
commercial suppliers or prepared as follows. To a solution of
starting amine (10 mmol) and triethylamine (15 mmol) in dry
dichloromethane (25 mL) was slowly added 2-chloroacetyl
chloride (10.5 mmol) in dry dichloromethane (10 mL). The
reaction mixture was stirred for 1-12 h at room temperature.
The reaction mixture was washed with 2 N HCl (1 × 30 mL)
and water (2 × 30 mL) and dried with sodium sulfate. The
solution was concentrated under reduced pressure.This crude
material was used without further purification.
2-Chloro-N-(9-methyl-9H-carbazol-3-yl)acetamide (10).
Reduction of 3-nitro-9-methylcarbazole gave 3-amino-9-meth-
ylcarbazole in good yield.50 To a solution of 3-amino-9-meth-
ylcarbazole (1.96 g, 10 mmol) and triethylamine (2.07 mL, 15
mmol) in dry dichloromethane (25 mL), a solution of chloro-
acetyl chloride (1.18 g, 10.5 mmol) in dry dichloromethane (10
mL) was added. The reaction mixture was stirred for 16 h at
room temperature. The reaction mixture was washed with 2
N HCl (1 × 30 mL) and water (2 × 30 mL) and dried with
sodium sulfate and the solvent evaporated, giving the title
compound as a brown solid (2.59 g, 95%). 1H NMR (300 MHz,
DMSO-d6) δ ppm 3.64 (s, 3 H), 4.28 (s, 2H), 7.18 (m, 1 H),
7.44 (t, J ) 7.14 Hz, 1 H), 7.55 (m, 3 H), 8.06 (d, J ) 7.7 Hz,
1 H), 8.04 (s, 1H), 10.32 (s, 1 H).
A stirred solution of 1-(tert-butyloxycarbonyl)-4-(piperidinyl)-
6-chloro-1,4-dihydrobenzo[d][1,3]oxazin-2-one (12.0 g, 32.5
mmol) in EtOAc (200 mL) was cooled to 0 °C. A 5 M solution
of hydrogen chloride in diethyl ether (500 mL) was then added,
and the resulting mixture was stirred at 0 °C for 4 h. The
precipitate formed was collected by filtration, washed with
ether, and vacuum-dried, giving the title compound 4g as a
white solid (mp 254-257 °C; 8.48 g, 97%). IR (KBr) 2945, 2732,
1717, 1494, 1199,1047, 759 cm-1. 1H NMR (300 MHz, DMSO-
d6 ) δ ppm 1.92 (d, J ) 13.18 Hz, 2 H), 2.65 (m, 2 H), 3.05 (m,
2 H), 3.30 (m, 2 H), 4.21 (tt, J ) 11.95, 3.57 Hz, 1 H), 5.14 (s,
2 H), 7.39 (m, 3 H), 8.65 (s, 1 H), 9.30 (s, 1 H).
5-Chloro-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4a). Following the procedure
described for the synthesis of 4g, compound 4a was prepared
from 2-amino-6-chlorobenzyl alcohol (2a) to afford a white solid
in 47% overall yield, mp 281-284 °C. IR (KBr) 2956, 2732,
1
1722, 1599, 1461, 1190, 1047, 778 cm-1. H NMR (300 MHz,
DMSO-d6) δ ppm 1.93 (d, J ) 13.32 Hz, 2 H), 2.67 (m, 2 H),
3.06 (m, 2 H), 3.30 (m, 2 H), 4.22 (t, J ) 11.86 Hz, 1 H), 5.26
(s, 2 H), 7.23 (m, 1 H), 7.40 (m, 2 H), 8.69 (s, 1 H), 9.34 (s, 1
H).
6-Fluoro-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4b). Following the procedure
described for the synthesis of 4g, compound 4b was prepared
from 2-amino-5-fluorobenzyl alcohol (2b) to afford a brown
solid in 23% overall yield, mp 254-256 °C. IR (KBr) 3136,
2-Chloro-N-[(4-aminophenyl)ethylphenylamine]acet-
amide (12). According to the general method, compound 12
was obtained from (4-aminophenyl)ethylphenylamine51 in 97%
yield. This crude material was used without further purifica-
1
2718, 1686, 1500, 1458, 1382, 1045, 758, 615 cm-1. H NMR
(300 MHz, DMSO-d6 ) δ ppm 1.92 (d, J ) 12.59 Hz, 2 H), 2.65
(m, J ) 12.70, 3.88 Hz, 2 H), 3.06 (m, 2 H), 3.29 (m, 2 H), 4.20
(tt, J ) 11.81, 3.64 Hz, 1 H), 5.13 (s, 2 H), 7.19 (m, 2 H), 7.41
(m, 1 H), 8.63 (s, 1 H), 9.25 (s, 1 H).
1
tion. H NMR (CDCl3) δ ppm 1.21 (t, J ) 7.14 Hz, 3H), 3.76
(d, J ) 7.14 Hz, 2H), 4.18 (s, 2H), 6.98 (m, 5H), 7.26 (m, 2H),
7.42 (d, J ) 8.8 Hz, 2H), 8.23 (s, 1H).
2-Chloro-N-dibenzofuran-2-ylacetamide (13). According
to the general method, compound 13 was obtained from
2-aminodibenzofuran52 in 86% yield. This crude material was
used without further purification. MS (APCI+) m/z: 260 (M +
H+).
2-Chloro-N-(3-amino-9-fluorenone)acetamide (14). Ac-
cording to the general method, compound 14 was obtained
from commercial 3-amino-9-fluorenone in 94% yield. This
crude material was used without further purification. 1H NMR
(CDCl3) δ ppm 4.18 (s, 2 H), 7.28 (m, 2 H), 7.45 (m, 2 H), 7.58
(m, 2 H), 7.98 (d, J ) 1.76 Hz, 1 H), 9.07 (s, 1 H).
2-Chloro-N-(2-amino-9-fluorenone)acetamide (15). Ac-
cording to the general method, compound 15 was obtained
from commercial 2-amino-9-fluorenone in 73% yield. This
crude material was used without further purification. 1H NMR
(300 MHz, DMSO-d6) δ ppm 4.26 (s, 2 H), 7.28 (m, 1 H), 7.54
(m, 2 H), 7.67 (m, 3 H), 7.89 (s, 1 H), 10.55 (s, 1 H).
2-Chloro-N-(4-aminobenzophenone)acetamide (16). Ac-
cording to the general method, compound 16 was obtained
from commercial 4-aminobenzophenone in 97% yield. This
crude material was used without further purification. 1H NMR
(300 MHz, DMSO-d6) δ ppm 4.30 (s, 2 H), 7.54 (m, 2 H), 7.68
(m, 7 H), 10.67 (s, 1 H).
2-Chloro-N-(4-amino-9-fluorenone)acetamide (24). Ac-
cording to the general method, compound 24 was obtained
from commercial 4-amino-9-fluorenone in 73% yield. This
crude material was used without further purification. 1H NMR
(300 MHz, DMSO-d6) δ ppm 4.44 (s, 2 H), 7.39 (m, 2 H), 7.51
(m, 2 H), 7.61 (m, 2 H), 7.70 (d, J ) 7.51 Hz, 1 H), 10.39 (s, 1
H).
8-Methoxy-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4c). Following the procedure
described for the synthesis of 4g, compound 4c was prepared
from 2-amino-3-methoxybenzyl alcohol (2c) to afford a white
solid in 42% overall yield, mp 228-230 °C. IR (KBr) 2697,
1708, 1390,1293, 1233,1082, 1028, 783, 737 cm-1. 1H NMR (300
MHz, DMSO-d6 ) δ ppm 2.03 (d, J ) 12.01 Hz, 2 H), 2.59 (m,
2 H), 2.90 (m, 2 H), 3.29 (m, 2 H), 3.87 (m, 4 H), 5.06 (s, 2 H),
6.88 (dd, J ) 6.52, 1.83 Hz, 1 H), 7.10 (m, 2 H), 8.45 (s, 1 H),
9.40 (s, 1 H).
1-Piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-
one Hydrochloride49 (4d). Following the procedure described
for the synthesis of 4g, compound 4d was prepared from
commercial 2-aminobenzyl alcohol (2d) to afford a white solid
in 55% overall yield, mp 253-256 °C. IR (KBr) 3442, 2945,
1
2735,1701, 1497,1387, 1292, 1204, 1036, 774 cm-1. H NMR
(300 MHz, DMSO-d6 ) δ ppm 1.92 (d, J ) 12.89 Hz, 2 H), 2.69
(m, 2 H), 3.08 (m, 2 H), 3.32 (d, J ) 12.15 Hz, 2 H), 4.23 (m,
J ) 11.88, 3.48 Hz, 1 H), 5.14 (s, 2 H), 7.14 (m, 1 H), 7.28 (d,
J ) 7.17 Hz, 1 H), 7.37 (m, 2 H), 8.69 (s, 1 H), 9.36 (s, 1 H).
6-Methyl-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4e). Following the procedure
described for the synthesis of 4g, compound 4e was prepared
from commercial 2-amino-5-methylbenzyl alcohol 2e to afford
a white solid in 72% overall yield, mp 259-261 °C. IR (KBr)
1
2941, 1701, 1508, 1300, 1216, 1047, 766 cm-1. H NMR (300
MHz, DMSO-d6 ) δ ppm 1.90 (d, J ) 12.59 Hz, 2 H), 2.26 (s, 3
H), 2.68 (m, 2 H), 3.05 (m, 2 H), 3.32 (d, J ) 12.89 Hz, 2 H),
4.19 (tt, J ) 11.82, 3.70 Hz, 1 H), 5.09 (s, 2 H), 7.08 (s, 1 H),
7.16 (m, 1 H), 7.26 (m, 1 H), 8.68 (s, 1 H), 9.32 (s, 1 H).
General Procedure for the Synthesis of Compounds
5a-z and 6a-m. The corresponding chloroacetamide (1.10
mmol) was added to a suspension of benzoxazinone (4a-g) (1
mmol) and K2CO3 (3 mmol) in dry DMF (10 mL) at room
temperature. After the reaction mixture was stirred overnight,
the solvent was removed under reduced pressure, and the
residue was partitioned in ethyl acetate and water and
extracted twice with ethyl acetate. The organic layer was
washed with brine, dried, filtered, and evaporated. The crude
products were purified by crystallization or column chroma-
8-Methyl-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one Hydrochloride (4f). Following the procedure
described for the synthesis of 4g, compound 4f was prepared
from commercial 2-amino-3-methylbenzyl alcohol (2f) to afford
a white solid in a 68% overall yield, mp 257-262 °C. IR (KBr)
2949, 2716, 1713, 1477, 1410, 1227, 1025, 772 cm-1. 1H NMR
(300 MHz, DMSO-d6) δ ppm 2.04 (d, J ) 13.62 Hz, 2 H), 2.38
(s, 3 H), 2.65 (m, J ) 12.89, 3.51 Hz, 2 H), 2.98 (m, 2 H), 3.28
(d, J ) 12.15 Hz, 2 H), 3.76 (ddd, J ) 11.49, 8.27, 3.51 Hz, 1

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2087
tography. Hydrochloride salt formation was usually a conve-
nient method for the purification of these compounds.
N-(4-Chlorophenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]oxazin-
1-yl)piperidin-1-yl]acetamide Hydrochloride (5f). Fol-
lowing the procedure described for the synthesis of 5a,
compound 5f was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chloro-N-
(4-chlorophenyl)acetamide (23), giving a white solid (yield
71%), mp 272-276 °C. IR (KBr) 3454, 3057, 1701, 1610, 1552,
1492, 1394, 1292, 1254, 1024 cm-1. 1H NMR (300 MHz, DMSO-
d6) δ ppm 1.99 (d, J ) 12.4 Hz, 2H), 2.90 (m, J ) 11.5 Hz,
2H), 3.40 (m, 2H), 3.63 (d, J ) 11.0 Hz, 2H), 4.20 (s, 2H), 4.28
(m, 1H), 5.15 (s, 2H), 7.12 (m, 1H), 7.29 (d, J ) 7.3 Hz, 1H),
7.40 (m, 4H), 7.69 (d, J ) 8.8 Hz, 2H), 10.28 (s, 1H), 11.35 (s,
1H).
2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-
yl]-N-(4-phenoxyphenyl)acetamide Hydrochloride (5a).
To a suspension of 1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one hydrochloride (4d) (0.268 g, 1 mmol) and K2CO3
(0.414 g, 3 mmol) in dry DMF (25 mL) 2-chloro-N-(phenoxy-
phenyl)acetamide (9) (0.28 g, 1.10 mmol) was added at room
temperature. After the reaction mixture was stirred overnight,
the solvent was removed under reduced pressure, and the
residue was partitioned in ethyl acetate (15 mL) and water
(15 mL) and extracted twice with ethyl acetate (2 × 15 mL).
The organic layer was washed with brine (1 × 25 mL), dried,
filtered, and evaporated. The crude was dissolved in ethanol
(10 mL), and 0.36 mL of a 2.8 M solution of hydrochloric acid
in absolute ethanol was added to collect a brown solid after it
was filtrated, washed with ethanol, and dried under vacuum
(0.37 g, 75%), mp 242-248 °C. IR (KBr) 3044, 1703, 1686,
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(4-cyclohexylphenyl)acetamide Hydrochlo-
ride (5g). Following the procedure described for the synthesis
of 5a, compound 5g was prepared from 6-chloro-1-piperidin-
4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g)
and 2-chloro-N-(4-cyclohexylphenyl)acetamide (8), giving a
white solid (yield 67%), mp 249-256 °C. IR (KBr) 2929, 1692,
1506, 1487, 1392, 1226, 1040, 751, 694 cm-1 1H NMR (300
.
MHz, DMSO-d6 ) δ ppm 2.01 (d, J ) 12.8 Hz, 2H), 2.90 (m, J
) 12.1 Hz, 2H), 3.41 (m, 2H), 3.63 (m, 2H), 4.18 (s, 2H), 4.29
(m, 1H), 5.16 (s, 2H), 6.96 (m, 2H), 7.03 (m, 2H), 7.12 (m, 2H),
7.35 (m, 5H), 7.67 (d, J ) 8.8 Hz, 2H), 10.26 (s, 1H), 11.13 (s,
1H). Anal. free base (C27H27N3O4‚0.5H2O) C, H, N.
1
1607, 1547, 1293, 1201, 1043, 830 cm-1. H NMR (300 MHz,
DMSO-d6) δ ppm 1.3 (m, 4 H), 1.7 (m, 6 H), 2.0 (d, J ) 15.7
Hz, 2 H), 2.4 (m, 1 H), 2.9 (q, J ) 12.5 Hz, 2 H), 3.3 (t, J )
11.9 Hz, 2 H), 3.6 (d, J ) 10.3 Hz, 2 H), 4.1 (s, 2 H), 4.2 (t, J
) 12.1 Hz, 1 H), 5.1 (s, 2 H), 7.1 (d, J ) 8.6 Hz, 2 H), 7.4 (m,
3 H), 7.5 (d, J ) 8.6 Hz, 2 H), 10.1 (br, 1 H), 10.5 (s, 1 H).
Anal. (C27H32ClN3O3‚HCl‚0.25H2O) C, H, N.
2-[4-(6-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(4-phenoxyphenyl)acetamide Hydrochlo-
ride (5b). Following the procedure described for the synthesis
of 5a, compound 5b was prepared from 6-methyl-1-piperidin-
4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4e)
and 2-chloro-N-(phenoxyphenyl)acetamide (9) to afford a white
solid (yield 54%), mp 234-237 °C. IR (KBr) 3148, 2970, 2449,
1691, 1541, 1507, 1233, 1038 cm-1. 1H NMR (300 MHz, DMSO-
d6) δ ppm 2.0 (d, J ) 14.1 Hz, 2 H), 2.2 (s, 3 H), 2.9 (m, 2 H),
3.3 (m, 2 H), 3.6 (d, J ) 12.1 Hz, 2 H), 4.1 (s, 2 H), 4.2 (m, 1
H), 5.1 (s, 2 H), 7.0 (m, 6 H), 7.2 (m, 2 H), 7.3 (t, J ) 7.8 Hz,
2 H), 7.6 (d, J ) 9.0 Hz, 2 H), 10.1 (s, 1 H), 10.6 (s, 1 H). Anal.
(C28H29N3O4‚HCl‚0.25H2O) C, H, N.
N-(4-Cyclohexylphenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]-
oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride (5h).
Following the procedure described for the synthesis of 5a,
compound 5h was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chloro-N-
(4-cyclohexylphenyl)acetamide (8) to afford a white solid (yield
68%), mp 256-260 °C. IR (KBr) 3422, 1701, 1609, 1550, 1393,
1292, 1260, 1205, 1043 cm-1. 1H NMR (300 MHz, DMSO-d6) δ
ppm 1.29 (m, 5H), 1.72 (m, 5H), 2.00 (d, J ) 13.2 Hz, 2H),
2.45 (m, 1H), 2.91 (m, J ) 11.7 Hz, 2H), 3.39 (m, 2H), 3.64 (m,
2H), 4.16 (s, 2H), 4.30 (m, 1H), 5.15 (s, 2H), 7.13 (m, 3H), 7.29
(d, J ) 7.3 Hz, 1H), 7.38 (m, 2H), 7.54 (d, J ) 8.2 Hz, 2H),
10.28 (s, 1H), 10.96 (s, 1H).
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(4-phenoxyphenyl)acetamide Hydrochlo-
ride (5c). Following the procedure described for the synthesis
of 5a, compound 5c was prepared from 6-chloro-1-piperidin-
4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g)
and 2-chloro-N-(phenoxyphenyl)acetamide (9) to afford a white
solid (yield 49%), mp 262-267 °C. IR (KBr) 2990, 1714, 1560,
N-(9-Methyl-9H-carbazol-3-yl)-2-[4-(2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(5i). Following the procedure described for the synthesis of
5a, compound 5i was prepared from 1-piperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chlo-
ro-N-(9-methyl-9H-carbazol-3-yl)acetamide (10) to afford a
white solid (yield 63%), mp 191-193 °C. IR (KBr) 3425, 3048,
1488, 1231, 1039, 950, 871, 751 cm-1 1H NMR (300 MHz,
.
DMSO-d6) δ ppm 2.0 (d, J ) 13.2 Hz, 2 H), 2.9 (m, 2 H), 3.3
(m, 2 H), 3.6 (d, 2 H), 4.1 (s, 2 H), 4.3 (m, 1 H), 5.1 (s, 2 H), 7.0
(m, 4 H), 7.1 (t, J ) 7.4 Hz, 1 H), 7.3 (m, 5 H), 7.6 (d, J ) 9.0
Hz, 2 H), 10.2 (s, 1 H), 10.6 (s, 1 H). Anal. (C27H26ClN3O4‚HCl‚
H2O) C, H, N.
1
1709, 1686, 1607, 1496, 1248, 1040, 771, 750 cm-1. H NMR
(300 MHz, DMSO-d6) δ ppm 2.03 (d, J ) 12.4 Hz, 2H), 2.93
(m, J ) 11.2 Hz, 2H), 3.42 (m, 2H), 3.69 (d, J ) 11.2 Hz, 2H),
3.86 (s, 3H), 4.22 (s, 2H), 4.32 (m, 1H), 5.17 (s, 2H), 7.13 (m,
1H), 7.20 (d, J ) 7.3 Hz, 1H), 7.30 (d, J ) 7.3 Hz, 1H), 7.43
(m, 3H), 7.58 (d, J ) 10.2 Hz, 2H), 7.65 (d, J ) 8.6 Hz, 1H),
8.06 (d, J ) 7.7 Hz, 1H), 8.47 (s, 1H), 10.29 (s, 1H), 11.09 (s,
1H). Anal. (C28H28N4O3‚HCl) C, H, N.
2-[4-(8-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-phenylacetamide Hydrochloride (5d). Fol-
lowing the procedure described for the synthesis of 5a,
compound 5d was prepared from 8-methyl-1-piperidin-4-yl-
1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4f) and
2-chloro-N-phenylacetamide (20), giving a white solid (yield
61%), mp 232-239 °C. IR (KBr) 3190, 1696, 1599, 1556, 951,
773, 726, 694 cm-1. 1H NMR (300 MHz, DMSO-d6) δ ppm 2.1
(d, J ) 13.7 Hz, 2 H), 2.4 (s, 3 H), 3.0 (m, 2 H), 3.2 (s, 2 H), 3.6
(m, 2 H), 3.8 (m, 1 H), 4.1 (s, 2 H), 5.0 (s, 2 H), 7.1 (m, 3 H),
7.2 (d, J ) 7.8 Hz, 1 H), 7.3 (t, J ) 6.5 Hz, 2 H), 7.6 (d, J ) 8.1
Hz, 2 H), 10.1 (s, 1 H), 10.6 (s, 1 H).
N-(4-Chlorophenyl)-2-[4-(8-methyl-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(5e). Following the procedure described for the synthesis of
5a, compound 5e was prepared from 8-methyl-1-piperidin-4-
yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4f) and
2-chloro-N-(4-chlorophenyl)acetamide (23), giving a white solid
(yield 57%), mp 245-253 °C. IR (KBr) 3277, 2991, 1726, 1681,
1597, 1541, 1492, 1280, 1255, 1201 cm-1. 1H NMR (300 MHz,
DMSO-d6) δ ppm 2.1 (d, J ) 13.2 Hz, 2 H), 2.4 (s, 3 H), 2.9 (m,
2 H), 3.3 (m, 2 H), 3.6 (d, J ) 2.9 Hz, 2 H), 3.8 (m, 1 H), 4.1 (s,
2 H), 5.0 (s, 2 H), 7.1 (m, 2 H), 7.2 (d, J ) 7.1 Hz, 1 H), 7.3 (d,
J ) 7.1 Hz, 2 H), 7.6 (m, 2 H), 10.2 (s, 1 H), 10.8 (s, 1 H).
2-[4-(5-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-ethyl-9H-carbazol-3-yl)acetamide Hydro-
chloride (5j). Following the procedure described for the
synthesis of 5a, compound 5j was prepared from 5-chloro-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-
ride (4a) and 2-chloro-N-(9-ethyl-9H-carbazol-3-yl)acetamide
(11) to give a white solid (yield 65%), mp 234 °C. IR (KBr)
1
1692, 1589, 1462, 1301, 1229, 1047, 783 cm-1. H NMR (300
MHz, DMSO-d6) δ ppm 1.3 (t, J ) 6.8 Hz, 3 H), 2.1 (d, J )
11.1 Hz, 2 H), 2.9 (m, 2 H), 3.4 (m, 2 H), 3.7 (d, J ) 11.6 Hz,
2 H), 4.2 (s, 2 H), 4.3 (m, 1 H), 4.4 (q, J ) 6.6 Hz, 2 H), 5.3 (s,
2 H), 7.2 (t, J ) 7.3 Hz, 1 H), 7.3 (d, J ) 7.1 Hz, 1 H), 7.5 (m,
3 H), 7.6 (m, 3 H), 8.1 (d, J ) 7.6 Hz, 1 H), 8.5 (s, 1 H), 10.2
(s, 1 H), 10.9 (s, 1 H). Anal. (C29H29ClN4O3‚HCl) C, H, N.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-ethyl-9H-carbazol-3-yl)acetamide Hydro-
chloride (5k). Following the procedure described for the
synthesis of 5a, compound 5k was prepared from 6-chloro-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-

2088 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6
Torrens et al.
ride (4g) and 2-chloro-N-(9-ethyl-9H-carbazol-3-yl)acetamide
(11) to give a white solid (yield 47%), mp 265-268 °C. IR (KBr)
2970,1712, 1691, 1492, 1376, 1294, 1201, 1043 cm-1. 1H NMR
(300 MHz, DMSO-d6) δ ppm 1.28 (t, J ) 7.0 Hz, 3H), 2.01 (d,
J ) 12.4 Hz, 2H), 2.90 (m, 2H), 3.43 (m, 2H), 3.68 (m, 2H),
4.27 (m, 3H), 4.41 (q, J ) 7.0 Hz, 2H), 5.16 (s, 2H), 7.17 (t, J
) 7.4 Hz, 1H), 7.44 (m, 4H), 7.61 (m, 3H), 8.05 (d, J ) 7.9 Hz,
1H), 8.47 (s, 1H), 10.33 (s, 1H), 11.16 (s, 1H). Anal. (C29H29-
ClN4O3‚HCl) C, H, N.
1109, 916, 768, 731 cm-1. 1H NMR (300 MHz, DMSO-d6) δ ppm
2.13 (d, J ) 12.8 Hz, 2H), 2.40 (s, 3H), 2.91 (m, 2H), 3.42 (m,
2H), 3.63 (d, J ) 10.2 Hz, 2H), 3.84 (m, 1H), 4.25 (s, 2H), 5.09
(s, 2H), 7.10 (m, 2H), 7.25 (d, J ) 6.8 Hz, 1H), 7.38 (t, J ) 7.4
Hz, 1H), 7.62 (m, 5H), 8.07 (s, 1H), 10.27 (s, 1H), 11.75 (s, 1H).
Anal. free base (C29H27N3O4‚0.5H2O) C, H, N.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-oxo-9H-fluoren-3-yl)acetamide Hydro-
chloride (5q). Following the procedure described for the
synthesis of 5a, compound 5q was prepared from 6-chloro-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-
ride (4g) and 2-chloro-N-(3-amino-9-fluorenone)acetamide (14),
giving a yellow solid (yield 68%), mp 245-249 °C. IR (KBr)
3421, 1701, 1609, 1560, 1371, 1298, 1201 cm-1. 1H NMR (300
MHz, DMSO-d6) δ ppm 2.01 (d, J ) 11.8 Hz, 2H), 2.88 (m,
2H), 3.42 (m, 2H), 3.66 (d, J ) 11.8 Hz, 2H), 4.30 (m, 3H),
5.16 (s, 2H), 7.39 (m, 4H), 7.60 (m, 5H), 8.08 (s, 1H), 10.39 (s,
1H), 11.75 (s, 1H). Anal. (C28H24ClN3O4‚HCl‚2H2O) C, H, N.
N-(9-Ethyl-9H-carbazol-3-yl)-2-[4-(8-methyl-2-oxo-4H-
benzo[d][1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hy-
drochloride (5l). Following the procedure described for the
synthesis of 5a, compound 5l was prepared from 8-methyl-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-
ride (4f) and 2-chloro-N-(9-ethyl-9H-carbazol-3-yl)acetamide
(11) to afford a white solid (yield 41%), mp 229-232 °C. IR
(KBr) 3449, 2976, 1710, 1685, 1490, 1384, 1326, 1225, 953,
1
745 cm-1. H NMR (300 MHz, DMSO-d6) δ ppm 1.28 (t, J )
7.0 Hz, 3H), 2.13 (d, J ) 12.8 Hz, 2H), 2.40 (s, 3H), 2.92 (m,
2H), 3.40 (m, 2H), 3.64 (d, J ) 11.0 Hz, 2H), 3.84 (m, 1H),
4.17 (s, 2H), 4.41 (q, J ) 7.0 Hz, 2H), 5.09 (s, 2H), 7.13 (m,
3H), 7.25 (d, J ) 7.3 Hz, 1H), 7.44 (m, 1H), 7.60 (m, 3H), 8.05
(d, J ) 7.7 Hz, 1H), 8.43 (s, 1H), 10.18 (s, 1H), 11.09 (s, 1H).
Anal. (C30H32N4 O3‚HCl) C, H, N.
N-[4-(Ethylphenylamino)phenyl]-2-[4-(8-methoxy-2-
oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-yl]acet-
amide Hydrochloride (5m). Following the procedure de-
scribed for the synthesis of 5a, compound 5m was prepared
from 8-methoxy-1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-
2-one hydrochloride (4c) and 2-chloro-N-[(4-aminophenyl)-
ethylphenylamine]acetamide (12) to afford a white solid (yield
54%), mp 216-218 °C. IR (KBr) 3422, 2980, 1701, 1510, 1492,
1388, 1287, 1252, 1088, 1029 cm-1. 1H NMR (300 MHz, CDCl3)
δ ppm 1.2 (t, J ) 7.1 Hz, 3 H), 2.2 (d, J ) 12.1 Hz, 2 H), 2.9
(m, 2 H), 3.3 (m, 2 H), 3.7 (d, J ) 11.1 Hz, 2 H), 3.8 (q, J ) 7.1
Hz, 2 H), 4.0 (s, 3 H), 4.1 (m, 1 H), 4.2 (s, 2 H), 5.2 (s, 2 H), 6.9
(m, 4 H), 7.1 (d, J ) 8.6 Hz, 2 H), 7.2 (m, 2 H), 7.3 (m, 2 H),
7.6 (d, J ) 8.6 Hz, 2 H), 10.2 (s, 1 H), 11.0 (s, 1 H). Anal.
(C30H34N4O4‚HCl‚H2O) C, H, N.
N-Dibenzofuran-2-yl-2-[4-(8-methoxy-2-oxo-4H-benzo-
[d][1,3]oxazin-1-yl)piperidin-1-yl]acetamide (5n). Follow-
ing the procedure described for the synthesis of 5a, base 5n
was prepared from 8-methoxy-1-piperidin-4-yl-1,4-dihydrobenzo-
[d][1,3]oxazin-2-one hydrochloride (4c) and 2-chloro-N-diben-
zofuran-2-ylacetamide (13) to afford a cream solid (yield 62%),
mp 88-92 °C. IR (KBr) 1718, 1483, 1286, 1223, 1191, 1079,
1037 cm-1. 1H NMR (300 MHz, CDCl3 ) δ ppm 2.0 (d, J ) 11.6
Hz, 2 H), 2.4 (t, J ) 10.9 Hz, 2 H), 2.9 (qd, J ) 12.3, 4.0 Hz,
2 H), 3.1 (d, J ) 11.6 Hz, 2 H), 3.2 (s, 2 H), 3.8 (m, 1 H), 3.9
(s, 3 H), 5.0 (s, 2 H), 6.8 (d, J ) 7.1 Hz, 1 H), 6.9 (d, J ) 7.6
Hz, 1 H), 7.1 (m, 1 H), 7.3 (t, J ) 7.6 Hz, 1 H), 7.5 (t, J ) 7.8
Hz, 1 H), 7.6 (m, 3 H), 8.0 (d, J ) 7.1 Hz, 1 H), 8.4 (d, J ) 2.0
Hz, 1 H), 9.4 (s, 1 H). Anal. (C28H27N3 O5‚0.5H2O) C, H, N.
2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-
yl]-N-(9-oxo-9H-fluoren-2-yl)acetamide Hydrochloride
(5r). Following the procedure described for the synthesis of
5a, compound 5r was prepared from 1-piperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chlo-
ro-N-(2-amino-9-fluorenone)acetamide (15) to afford a yellow
solid (yield 70%), mp 276-280 °C. IR (KBr) 3241, 1696, 1608,
1
1560, 1463, 1391, 1293, 1259, 1206, 739 cm-1. H NMR (300
MHz, DMSO-d6) δ ppm 2.00 (d, J ) 12.6 Hz, 2H), 2.90 (m, J
) 12.6 Hz, 2H), 3.43 (m, 2H), 3.66 (d, J ) 9.7 Hz, 2H), 4.21 (s,
2H), 4.28 (m, 1H), 5.16 (s, 2H), 7.13 (m, 1H), 7.34 (m, 4H),
7.59 (d, J ) 7.0 Hz, 2H), 7.76 (m, 3H), 8.00 (s, 1H), 10.26 (s,
1H), 11.36 (s, 1H).
2-[4-(6-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-oxo-9H-fluoren-2-yl)-acetamide Hydro-
chloride (5s). Following the procedure described for the
synthesis of 5a, compound 5s was prepared from 6-methyl-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-
ride (4e) and 2-chloro-N-(2-amino-9-fluorenone)acetamide (15)
to afford a yellow solid (yield 43%), mp 281-285 °C. IR (KBr)
2985, 1701, 1604, 1561, 1466, 1300, 1262 cm-1. 1H NMR (300
MHz, DMSO-d6) δ ppm 2.0 (d, J ) 11.7 Hz, 2 H), 2.3 (s, 3 H),
2.9 (m, 2 H), 3.2 (m, 2 H), 3.6 (d, 2 H), 4.2 (m, 3 H), 5.1 (s, 2
H), 7.1 (s, 1 H), 7.3 (m, 3 H), 7.6 (m, 2 H), 7.7 (m, 3 H), 8.0 (s,
1 H), 10.3 (s, 1 H), 11.4 (s, 1 H). Anal. free base (C29H27 N3O4)
C, H, N.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-oxo-9H-fluoren-2-yl)acetamide Hydro-
chloride (5t). Following the procedure described for the
synthesis of 5a, compound 5t was prepared from 6-chloro-1-
piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochlo-
ride (4g) and 2-chloro-N-(2-amino-9-fluorenone)acetamide (15)
to afford a yellow solid (yield 59%), mp >300 °C. IR (KBr) 2999,
1707, 1603, 1561, 1490, 1463, 1298, 1200 cm-1. 1H NMR (300
MHz, DMSO-d6) δ ppm 2.0 (d, J ) 11.7 Hz, 2 H), 2.8 (m, 2 H),
3.1 (m, 2 H), 3.5 (d, 2 H), 4.3 (m, 3 H), 5.2 (s, 2 H), 7.3 (m, 1
H), 7.4 (m, 3 H), 7.6 (m, 2 H), 7.7 (m, 3 H), 8.0 (s, 1 H), 10.3 (s,
1 H), 11.4 (s, 1 H). Anal. free base (C28H24Cl N3O4) C, H, N.
2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-
yl]-N-(9-oxo-9H-fluoren-3-yl)acetamide Hydrochloride
(5o). Following the procedure described for the synthesis of
5a, compound 5o was prepared from 1-piperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chlo-
ro-N-(3-amino-9-fluorenone)acetamide (14), giving a yellow
solid (yield 72%), mp >275 °C. IR (KBr) 3433, 1705, 1609,
N-(4-Benzoylphenyl)-2-[4-(8-methyl-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(5u). Following the procedure described for the synthesis of
5a, compound 5u was prepared from 8-methyl-1-piperidin-4-
yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4f) and
2-chloro-N-(4-aminobenzophenone)acetamide (16), giving a
white solid (yield 71%), mp 217-220 °C. IR (KBr) 3432, 2894,
1
1557, 1467, 1451, 1297, 1253, 1111, 769 cm-1. H NMR (300
MHz, DMSO-d6) δ ppm 2.02 (d, J ) 12.6 Hz, 2H), 2.91 (m, J
) 12.6 Hz, 2H), 3.43 (m, 2H), 3.67 (d, J ) 9.9 Hz, 2H), 4.26
(m, 3H), 5.16 (s, 2H), 7.13 (m, 1H), 7.30 (d, J ) 7.5 Hz, 1H),
7.40 (m, 3H), 7.64 (m, 5H), 8.06 (s, 1H), 10.29 (s, 1H), 11.46
(s, 1H). Anal. (C28H25N3O4‚HCl) C, H, N.
1701, 1649, 1597,1541, 1281, 1033, 925, 857 cm-1 1H NMR
.
(300 MHz, DMSO-d6) δ ppm 2.1 (d, J ) 13.4 Hz, 2 H), 2.4 (s,
3 H), 2.9 (m, 2 H), 3.3 (m, 2 H), 3.6 (d, J ) 11.4 Hz, 2 H), 3.8
(m, 1 H), 4.1 (s, 2 H), 5.0 (s, 2 H), 7.1 (m, 2 H), 7.2 (d, J ) 7.5
Hz, 1 H), 7.5 (m, 2 H), 7.6 (dd, J ) 6.9, 2.1 Hz, 1 H), 7.7 (dd,
J ) 8.2, 1.3 Hz, 2 H), 7.8 (s, 4 H), 10.2 (s, 1 H), 10.9 (s, 1 H).
Anal. (C29H29N3O4‚HCl‚0.5H2O) C, H, N.
2-[4-(8-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-oxo-9H-fluoren-3-yl)acetamide Hydro-
chloride (5p). Following the procedure described for the
synthesis of 5a, compound 5p was prepared from 8-methyl-
1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydro-
chloride (4f) and 2-chloro-N-(3-amino-9-fluorenone)acetamide
(14), giving a yellow solid (yield 63%), mp 233-236 °C. IR
(KBr) 3410, 3014, 1701, 1609, 1561, 1450, 1371, 1285, 1237,
N-(4-Benzoylphenyl)-2-[4-(6-chloro-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(5v). Following the procedure described for the synthesis of
5a, compound 5v was prepared from 6-chloro-1-piperidin-4-

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2089
yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g) and
2-chloro-N-(4-aminobenzophenone)acetamide (16), giving a
white solid (yield 60%), mp 256-259 °C. IR (KBr) 3449, 3051,
2 H), 7.7 (d, J ) 8.8 Hz, 2 H), 7.9 (d, J ) 8.8 Hz, 2 H), 10.2 (s,1
H), 10.8 (s, 1 H). Anal. (C23H25N3O4‚HCl‚1.5H2O) C, H, N.
N-(4-Acethylphenyl)-2-[4-(6-chloro-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(6b). Following the procedure described for the synthesis of
5a, compound 6b was prepared from 6-chloro-1-piperidin-4-
yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g) and
N-(acetylphenyl)-2-chloroacetamide (17) to afford a white solid
(yield 40%), mp >244 °C (dec). IR (KBr) 3579, 3475, 2992,
1
1708, 1599, 1541, 1315, 1203, 1041, 949, 702 cm-1. H NMR
(300 MHz, DMSO-d6) δ ppm 2.0 (d, J ) 13.2 Hz, 2 H), 2.9 (m,
2 H), 3.3 (m, 2 H), 3.6 (d, J ) 9.9 Hz, 2 H), 4.2 (s, 2 H), 4.2 (m,
1 H), 5.1 (s, 2 H), 7.3 (m, 3 H), 7.5 (t, J ) 7.3 Hz, 2 H), 7.6 (t,
J ) 7.9 Hz, 1 H), 7.7 (m, 2 H), 7.7 (m, 4 H), 10.2 (s, 1 H), 10.9
(s, 1 H). Anal. (C28H26ClN3O4‚HCl‚H2O) C, H, N.
1
1717, 1667, 1600, 1545, 1263, 1041, 948 cm-1. H NMR (300
2-{2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-
1-yl]acetylamino}benzoic Acid Methyl Ester (5w). Fol-
lowing the procedure described for the synthesis of 5a,
compound 5w was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and methyl-N-
(chloroacetyl)antranilate (21) to afford the base as a white solid
(yield 42%), mp 180-182 °C. IR (KBr) 3232, 1702, 1583, 1521,
MHz, DMSO-d6) δ ppm 2.0 (d, J ) 13.7 Hz, 2 H), 2.5 (s, 3 H),
2.9 (m, 2 H), 3.4 (m, 2 H), 3.7 (d, J ) 11.9 Hz, 2 H), 4.2 (s, 2
H), 4.3 (m, 1 H), 5.1 (s, 2 H), 7.4 (m, 3 H), 7.7 (d, J ) 8.6 Hz,
2 H), 8.0 (d, J ) 8.6 Hz, 2 H), 10.2 (s, 1 H), 11.0 (s, 1 H). Anal.
(C23H24ClN3O4‚HCl‚H2O) C, H, N.
N-(4-Acethylphenyl)-2-[4-(6-methyl-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(6c). Following the procedure described for the synthesis of
5a, compound 6c was prepared from 6-methylpiperidin-4-yl-
1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4e) and
N-(acetylphenyl)-2-chloroacetamide (17) to afford a white solid
(yield 54%), mp 273-277 °C. IR (KBr) 2927, 1705, 1666, 1594,
1
1450, 1385, 1262, 1204, 1090, 1045, 772, 749 cm-1. H NMR
(300 MHz, CDCl3) δ ppm 1.9 (d, J ) 11.7 Hz, 2 H), 2.4 (td, J
) 11.6, 1.8 Hz, 2 H), 3.0 (qd, J ) 12.4, 3.9 Hz, 2 H), 3.1 (d, J
) 11.3 Hz, 2 H), 3.2 (s, 2 H), 4.0 (s, 3 H), 4.2 (qd, J ) 12.3, 3.8
Hz, 1 H), 5.1 (s, 2 H), 7.1 (q, J ) 7.1 Hz, 2 H), 7.2 (t, J ) 6.1
Hz, 1 H), 7.3 (m, 1 H), 7.5 (d, J ) 8.2 Hz, 1 H), 7.5 (m, 1 H),
8.0 (dd, J ) 8.0, 1.6 Hz, 1 H), 8.8 (m, 1 H), 12.1 (s, 1 H).
1595, 1508, 1267, 1117, 946, 839 cm-1 1H NMR (300 MHz,
.
DMSO-d6) δ ppm 2.0 (d, J ) 13.2 Hz, 2 H), 2.2 (s, 3 H), 2.5 (s,
3 H), 2.9 (m, 2 H), 3.4 (m, 2 H), 3.6 (d, J ) 12.1 Hz, 2 H), 4.2
(m, 3 H), 5.1 (s, 2 H), 7.1 (s, 1 H), 7.2 (m, 2 H), 7.7 (d, J ) 8.8
Hz, 2 H), 7.9 (d, J ) 8.8 Hz, 2 H), 10.2 (br, 1 H), 10.9 (s, 1 H).
Anal. free base (C24H27N3O4‚1.2H2O) C, H, N.
2-{2-[4-(8-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)pi-
peridin-1-yl]acetylamino}benzoic Acid Methyl Ester (5x).
Following the procedure described for the synthesis of 5a,
compound 5x was prepared from 8-methyl-1-piperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4f) and meth-
yl-N-(chloroacetyl)antranilate (21) to afford the base as a white
solid (yield 34%), mp 169-171 °C. IR (KBr) 3202, 1727, 1705,
N-(2-Benzoylphenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]oxazin-
1-yl)piperidin-1-yl]acetamide Hydrochloride (6d). Fol-
lowing the procedure described for the synthesis of 5a,
compound 6d was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and N-(2-ben-
zoylphenyl)-2-chloroacetamide (22) to afford a white solid (yield
58%), mp 211-216 °C. IR (KBr) 3260, 3058, 1681, 1610, 1296,
1
1508, 1449, 1270, 1215, 1089, 1033, 765 cm-1. H NMR (300
MHz, CDCl3) δ ppm 1.9 (d, J ) 12.3 Hz, 2 H), 2.3 (t, J ) 12.7
Hz, 2 H), 2.4 (s, 3 H), 3.0 (m, 4 H), 3.2 (s, 2 H), 3.4 (m, 1 H),
4.1 (s, 3 H), 5.0 (s, 2 H), 7.1 (m, 3 H), 7.2 (d, J ) 7.3 Hz, 1 H),
7.5 (m, 1 H), 8.0 (dd, J ) 8.0, 1.7 Hz, 1 H), 8.8 (d, J ) 8.4 Hz,
1 H), 12.2 (s, 1 H).
1036, 954, 772 cm-1 1H NMR (300 MHz, DMSO-d6) δ ppm
.
1.9 (d, J ) 13.7 Hz, 2 H), 2.8 (m, 2 H), 3.1 (m, 2 H), 3.3 (d, J
) 10.6 Hz, 2 H), 3.9 (s, 2 H), 4.2 (t, J ) 10.3 Hz, 1 H), 5.1 (s,
2 H), 7.1 (t, J ) 7.1 Hz, 1 H), 7.4 (m, 8 H), 7.6 (m, 2 H), 7.7 (d,
J ) 7.1 Hz, 2 H), 10.1 (br, 1 H), 10.8 (s, 1 H).
2-{2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)pi-
peridin-1-yl]acetylamino}benzoic Acid Methyl Ester (5y).
Following the procedure described for the synthesis of 5a,
compound 5y was prepared from 6-chloro-1-piperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g) and methyl-
N-(chloroacetyl)antranilate (21) to afford the base as a white
solid (yield 22%), mp 153-156 °C. IR (KBr) 1702, 1508, 1448,
1259, 1201, 1090, 756 cm-1. 1H NMR (300 MHz, CDCl3) δ ppm
1.9 (d, J ) 11.4 Hz, 2 H), 2.5 (t, J ) 11.4 Hz, 2 H), 2.9 (m, 2
H), 3.1 (d, J ) 11.5 Hz, 2 H), 3.2 (s, 2 H), 4.0 (s, 3 H), 4.2 (qd,
J ) 12.6, 3.9 Hz, 1 H), 5.1 (s, 2 H), 7.1 (m, 2 H), 7.3 (m, 1 H),
7.4 (d, J ) 8.8 Hz, 1 H), 7.6 (m, 1 H), 8.1 (dd, J ) 7.9, 1.6 Hz,
1 H), 8.8 (d, J ) 8.4 Hz, 1 H), 12.1 (s, 1 H).
2-{2-[4-(6-Methyl-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)pi-
peridin-1-yl]acetylamino}benzoic Acid Methyl Ester (5z).
Following the procedure described for the synthesis of 5a,
compound 5z was prepared from 6-methylpiperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4e) and meth-
yl-N-(chloroacetyl)antranilate (21) to afford a white solid (yield
38%), mp 152-155 °C. IR (KBr) 1701, 1509, 1448, 1265, 1219,
1091, 756 cm-1. 1H NMR (300 MHz, CDCl3) δ ppm 1.9 (d, J )
11.4 Hz, 2 H), 2.3 (s, 3 H), 2.4 (m, 2 H), 2.9 (qd, J ) 12.4, 3.8
Hz, 2 H), 3.1 (d, J ) 11.4 Hz, 2 H), 3.2 (s, 2 H), 4.0 (s, 3 H), 4.2
(m, 1 H), 5.0 (s, 2 H), 7.0 (s, 1 H), 7.1 (m, 2 H), 7.3 (d, J ) 8.4
Hz, 1 H), 7.6 (t, J ) 7.0 Hz, 1 H), 8.1 (dd, J ) 8.1, 1.6 Hz, 1
H), 8.8 (m, 1 H), 12.1 (s, 1 H).
N-(2-Benzoylphenyl)-2-[4-(8-methyl-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(6e). Following the procedure described for the synthesis of
5a, compound 6e was prepared from 8-methyl-1-piperidin-4-
yl-1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4f) and
N-(2-benzoylphenyl)-2-chloroacetamide (22) to afford a white
solid (yield 45%), mp 168-176 °C. IR (KBr) 3413, 2961, 1686,
1606, 1282, 1033, 951, 775 cm-1. 1H NMR (300 MHz, DMSO-
d6) δ ppm 2.0 (d, J ) 13.4 Hz, 2 H), 2.3 (s, 3 H), 2.8 (m, 2 H),
3.0 (m, 2 H), 3.3 (d, J ) 10.8 Hz, 2 H), 3.7 (t, J ) 12.2 Hz, 1
H), 3.8 (s, 2 H), 5.0 (s, 2 H), 7.0 (m, 2 H), 7.2 (d, J ) 7.7 Hz, 1
H), 7.3 (t, J ) 7.5 Hz, 1 H), 7.4 (m, 4 H), 7.6 (m, 2 H), 7.7 (d,
J ) 7.7 Hz, 2 H), 10.0 (s, 1 H), 10.7 (s, 1 H).
N-(2-Benzoylphenyl)-2-[4-(6-chloro-2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(6f). Following the procedure described for the synthesis of
5a, compound 6f was prepared from 6-chloro-1-piperidin-4-yl-
1,4-dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g) and
N-(2-benzoylphenyl)-2-chloroacetamide (22) to afford a white
solid (yield 56%), mp 167-178 °C. IR (KBr) 3259, 1686, 1491,
1299, 1205, 1041, 956, 770 cm-1. 1H NMR (300 MHz, DMSO-
d6) δ ppm 1.9 (d, J ) 12.8 Hz, 2 H), 2.7 (m, 2 H), 3.1 (m, 2 H),
3.3 (d, J ) 10.6 Hz, 2 H), 3.9 (s, 2 H), 4.2 (m, 1 H), 5.1 (s, 2 H),
7.4 (m, 5 H), 7.5 (m, 3 H), 7.6 (m, 2 H), 7.7 (d, J ) 8.1 Hz, 2
H), 10.0 (s, 1 H), 10.8 (s, 1 H).
N-(4-Acethylphenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]oxazin-
1-yl)piperidin-1-yl]acetamide Hydrochloride (6a). Fol-
lowing the procedure described for the synthesis of 5a,
compound 6a was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and N-(acetyl-
phenyl)-2-chloroacetamide (17) to afford a white solid (yield
70%), mp >280 °C. IR (KBr) 3448, 3044, 1708, 1600, 1395,
2-[4-(6-Fluoro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-quinolin-6-ylacetamide (6g). Following the
procedure described for the synthesis of 5a, compound 6g was
prepared from 6-fluoropiperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one hydrochloride (4b) and 2-chloro-N-quinolin-6-
ylacetamide53 (18) to afford the base as a cream solid (yield
71%), mp 84 °C. IR (KBr) 1701, 1500, 1458, 1272, 1205, 1044,
1
1261, 1043, 948, 842, 771 cm-1. H NMR (300 MHz, DMSO-
d6) δ ppm 2.0 (d, J ) 13.5 Hz, 2 H), 2.5 (s, 3 H), 2.9 (m, 2 H),
3.3 (m, 2 H), 3.6 (d, J ) 11.4 Hz, 2 H), 4.1 (s, 2 H), 4.3 (m, 1
H), 5.1 (s, 2 H), 7.1 (m, 1 H), 7.2 (d, J ) 7.3 Hz, 1 H), 7.3 (m,
1
768 cm-1. H NMR (300 MHz, CDCl3) δ ppm 1.9 (d, J ) 12.1
Hz, 2 H), 2.5 (t, J ) 11.1 Hz, 2 H), 2.9 (qd, J ) 12.5, 4.0 Hz,

2090 Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6
Torrens et al.
2 H), 3.1 (d, J ) 11.6 Hz, 2 H), 3.3 (s, 2 H), 3.8 (m, 1 H), 5.1
(s, 2 H), 6.9 (dd, J ) 7.6, 2.5 Hz, 1 H), 7.0 (m, 2 H), 7.4 (dd, J
) 8.1, 4.0 Hz, 1 H), 7.8 (dd, J ) 8.8, 2.3 Hz, 1 H), 8.1 (d, J )
9.1 Hz, 1 H), 8.1 (d, J ) 8.6 Hz, 1 H), 8.3 (d, J ) 2.0 Hz, 1 H),
8.8 (m, 1 H), 9.4 (s, 1 H). Anal. (C24H23FN4O3‚0.5H2O) C, H,
N.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-quinolin-6-ylacetamide (6h). Following the
procedure described for the synthesis of 5a, compound 6h was
prepared from 6-chloropiperidin-4-yl-1,4-dihydrobenzo[d][1,3]-
oxazin-2-one hydrochloride (4g) and 2-chloro-N-quinolin-6-
ylacetamide53 (18) to afford the base as a cream solid (yield
64%), mp 87-89 °C. IR (KBr) 3410, 1718, 1604, 1527, 1497,
1379, 1199, 1043 cm-1. 1H NMR (300 MHz, CDCl3) δ ppm 1.9
(d, J ) 10.1 Hz, 2 H), 2.5 (m, 2 H), 2.9 (qd, J ) 12.5, 4.0 Hz,
2 H), 3.1 (d, J ) 11.6 Hz, 2 H), 3.3 (s, 2 H), 3.8 (m, 1 H), 5.1
(s, 2 H), 7.1 (s, 1 H), 7.1 (m, 2 H), 7.4 (dd, J ) 8.6, 4.0 Hz, 1
H), 7.8 (dd, J ) 9.1, 2.5 Hz, 1 H), 8.1 (d, J ) 9.1 Hz, 1 H), 8.2
(d, J ) 8.1 Hz, 1 H), 8.4 (d, J ) 2.5 Hz, 1 H), 8.8 (d, J ) 2.5
Hz, 1 H), 9.4 (s, 1 H). Anal. (C24H23ClN4O3‚0.5H2O) C, H, N.
N-(4-Cyanophenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]oxazin-
1-yl)piperidin-1-yl]acetamide Hydrochloride (6i). Fol-
lowing the procedure described for the synthesis of 5a,
compound 6i was prepared from 1-piperidin-4-yl-1,4-dihydro-
benzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chloro-N-
(4-cyanophenyl)acetamide (19) to afford a white solid (yield
37%), mp 268 °C (dec). IR (KBr) 3401, 2992, 2217, 1708, 1600,
1538, 1391, 1042, 950, 842 cm-1. 1H NMR (300 MHz, DMSO-
d6) δ ppm 2.0 (d, J ) 12.7 Hz, 2 H), 2.9 (m, 2 H), 3.4 (m, 2 H),
3.7 (d, J ) 11.5 Hz, 2 H), 4.3 (m, 3 H), 5.1 (s, 2 H), 7.1 (m, 1
H), 7.3 (d, J ) 7.8 Hz, 1 H), 7.4 (m, 2 H), 7.8 (m, 4 H), 10.2 (s,
1 H), 11.1 (s, 1 H). Anal. (C22H22N4O3‚HCl‚1.2H2O) C, H, N.
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4d) and 2-chlo-
ro-N-(4-amino-9-fluorenone)acetamide (24) to afford a white
solid (yield 75%), mp 270-273 °C. IR (KBr) 1710, 1698, 1608,
1
1541, 1466, 1390, 1292, 1263, 1201, 737 cm-1. H NMR (300
MHz, DMSO-d6) δ ppm 2.03 (d, J ) 12.1 Hz, 2H), 2.90 (m, J
) 11.2 Hz, 2H), 3.49 (m, 2H), 3.70 (d, J ) 11.2 Hz, 2H), 4.29
(m, 1H), 4.40 (s, 2H), 5.16 (s, 2H), 7.14 (m, 1H), 7.30 (d, J )
7.3 Hz, 1H), 7.42 (m, 4H), 7.61 (m, 4H), 7.82 (d, J ) 7.1 Hz,
1H), 10.29 (s, 1H), 10.96 (s, 1H). Anal. (C28H25N3O4‚HCl‚
0.3H2O) C, H, N.
General Procedure for the Synthesis of Compounds
7a-c by Reduction of Fluorenones Derivatives 5o-q. To
the ketone (0.15 mmol) dissolved in methanol (4 mL), a sodium
borohydride (0.30 mmol) solution in methanol (2 mL) was
added dropwise. After the mixture was stirred for 30 min at
room temperature, a further aliquot of sodium borohydride
(0.30 mmol) was added. After the mixture was stirred for 30
min, the solvent was evaporated and the residue was parti-
tioned between ethyl acetate and water. The organic layer was
washed with brine, dried over Na2SO4, filtered, and evapo-
rated. The crude products were purified by crystallization or
column chromatography. The hydrochloride salt is a good
method for purification of these compounds.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(9-hydroxy-9H-fluoren-3-yl)acetamide Hy-
drochloride (7a). Compound 7a was prepared in a similar
manner as described in the general procedure by reduction of
compound 5q to give a yellow solid (yield 72%), mp 219-222
°C. IR (KBr) 3422, 3045, 1701, 1559, 1491, 1295, 1200, 1042
1
cm-1. H NMR (300 MHz, DMSO-d6) δ ppm 2.01 (d, J ) 11.9
Hz, 2H), 2.88 (m, 2H), 3.39 (m, 2H), 3.66 (d, J ) 9.8 Hz, 2H),
4.27 (m, 3H), 5.16 (s, 2H), 5.45 (s, 1H), 5.86 (broad, 1H), 7.36
(m, 5H), 7.54 (m, 3H), 7.64 (d, J ) 7.2 Hz, 1H), 8.06 (s, 1H),
10.28 (s, 1H), 11.17 (s, 1H). Anal. (C28H26ClN3O4‚HCl‚1.2H2O)
C, H, N.
2-[4-(6-Chloro-2-oxo-4H-benzo[d][1,3]oxazin-1-yl)piper-
idin-1-yl]-N-(4-cyanophenyl)acetamide Hydrochloride
(6j). Following the procedure described for the synthesis of
5a, compound 6j was prepared from 6-chloropiperidin-4-yl-1,4-
dihydrobenzo[d][1,3]oxazin-2-one hydrochloride (4g) and 2-chlo-
ro-N-(4-cyanophenyl)acetamide (19) to afford a white solid
(yield 82%), mp 274-278 °C. IR (KBr) 3414, 2986, 2219, 1721,
N-(9-Hydroxy-9H-fluoren-3-yl)-2-[4-(2-oxo-4H-benzo[d]-
[1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hydrochloride
(7b). Compound 7b was prepared in a similar manner as
described in the general procedure by reduction of compound
5o to give a yellow solid (yield 68%), mp 270-273 °C. IR (KBr)
3328, 3071, 2547, 1715, 1691, 1606, 1259, 1045, 775 cm-1. 1H
NMR (300 MHz, DMSO-d6) δ ppm 2.0 (d, J ) 11.5 Hz, 2 H),
2.9 (m, 2 H), 3.4 (m, 2 H), 3.7 (d, J ) 12.3 Hz, 2 H), 4.2 (s, 2
H), 4.3 (m, 1 H), 5.1 (s, 2 H), 5.4 (s, 1 H), 7.1 (m, 1 H), 7.3 (m,
2 H), 7.3 (m, 3 H), 7.5 (dd, J ) 8.2, 1.8 Hz, 1 H), 7.6 (m, 2 H),
7.6 (d, J ) 7.1 Hz, 1 H), 8.0 (d, J ) 1.6 Hz, 1 H), 10.1 (s, 1 H),
10.7 (s, 1 H). Anal. (C28H27N3O4‚HCl) C, H, N.
N-(9-Hydroxy-9H-fluoren-3-yl)-2-[4-(8-methyl-2-oxo-
4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-yl]acetamide Hy-
drochloride (7c). Compound 7c was prepared in a similar
manner as described in general procedure by reduction of
compound 5p to give a yellow solid (yield 64%), mp 207-212
°C. IR (KBr) 3435, 1679, 1390, 1263, 774 cm-1. 1H NMR (300
MHz, DMSO-d6) δ ppm 2.13 (d, J ) 13.3 Hz, 2H), 2.40 (s, 3H),
2.91 (m, J ) 12.0 Hz, 2H), 3.36 (m, 2H), 3.63 (d, J ) 10.8 Hz,
2H), 3.83 (m, 1H), 4.18 (s, 2H), 5.09 (s, 2H), 5.45 (s, 1H), 5.86
(broad, 1H), 7.11 (m, 2H), 7.33 (m, 3H), 7.55 (m, 3H), 7.64 (d,
J ) 7.3 Hz, 1H), 8.05 (s, 1H), 10.19 (s, 1H), 11.22 (s, 1H). Anal.
(C29H29N3O4‚HCl‚0.75H2O) C, H, N.
1
1602, 1541, 1313, 1200, 1040, 842 cm-1. H NMR (300 MHz,
DMSO-d6) δ ppm 2.0 (d, J ) 12.6 Hz, 2 H), 2.9 (m, 2 H), 3.3
(m, 2 H), 3.6 (d, J ) 12.2 Hz, 2 H), 4.2 (s, 2 H), 4.3 (m,1H), 5.1
(s, 2 H), 7.4 (m, 3 H), 7.8 (s, 4 H), 10.2 (s, 1H), 11.0 (s, 1 H).
Anal. (C22H21ClN4O3‚HCl‚0.5H2O) C, H, N.
2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)-piperidin-1-
yl]-N-phenylacetamide Hydrochloride (6k). Following the
procedure described for the synthesis of 5a, compound 6k was
prepared from 1-piperidin-4-yl-1,4-dihydrobenzo[d][1,3]oxazin-
2-one hydrochloride (4d) and 2-chloro-N-phenylacetamide (20)-
to afford a white solid (yield 69%), mp 262-272 °C. IR (KBr)
3405, 3068, 1707, 1609, 1557, 1259, 1043, 947 cm-1. 1H NMR
(300 MHz, DMSO-d6) δ ppm 2.0 (d, J ) 13.4 Hz, 2 H), 2.9 (m,
2 H), 3.3 (m, 2 H), 3.6 (d, J ) 11.7 Hz, 2 H), 4.1 (s, 2 H), 4.3
(m, 1 H), 5.1 (s, 2 H), 7.1 (dd, J ) 7.3, 5.9 Hz, 2 H), 7.3 (m, 5
H), 7.6 (d, J ) 8.5 Hz, 2 H), 10.1 (s, 1 H), 10.6 (s, 1 H). Anal.
(C21H23N3O3‚HCl‚0.5H2O) C, H, N.
N-(4-Benzoylphenyl)-2-[4-(2-oxo-4H-benzo[d][1,3]oxazin-
1-yl)piperidin-1-yl]acetamide (6l). Following the procedure
described for the synthesis of 5a, compound 6l was prepared
from 1-piperidin-4-yl-1,4-dihydro-benzo[d][1,3]oxazin-2-one hy-
drochloride (4d) and 2-chloro-N-(4-aminobenzophenone)acet-
amide (16) to afford a white solid (yield 66%), mp 133-137
°C. IR (KBr) 3630, 3449, 3249, 1682, 1600, 1516, 1498, 1316,
Biological Methods. In Vitro NPY Y5 Membrane Bind-
ing Assays. A modification of the method previously described
by Hu48 was used. C6 cells were transfected with the rat Y5
receptor and grown under standard culture conditions in 150
cm2 dishes. Cells harvested from five dishes were collected and
centrifuged, and the pellets were washed, homogenized, and
centrifuged again. The pellet was resuspended in 8 mL of
membrane buffer (Tris-HCl 25 mM, NaCl 120 mM, KCl 5 mM,
KH2PO4 1.2 mM, CaCl2 2.5 mM, MgSO4 1.2 mM, BSA 0.15
mg/mL, bacitracin 0.5 mg/mL, pH 7,4) and rehomogenized.
1
1282, 1045, 757, 697 cm-1. H NMR (300 MHz, DMSO-d6) δ
ppm 1.73 (d, J ) 11.7 Hz, 2 H), 2.36 (m, J ) 11.2 Hz, H), 2.61
(m, J ) 11.7 Hz, 2 H), 2.98 (d, J ) 10.8 Hz, 2 H), 3.22 (s, 2H),
3.87 (m, J ) 11.7 Hz, 1 H), 5.11 (s, 2 H), 7.09 (t, J ) 7.3 Hz,
1 H), 7.27 (d, J ) 7.3 Hz, 2 H), 7.36 (t, J ) 7.7 Hz, 1 H), 7.54
(t, J ) 7.3 Hz, 2 H), 7.69 (m, 5 H), 7.83 (s, 1 H), 10.18 (s, 1 H).
Anal. (C28H27N3O4‚1H2O) C, N. H: calcd, 6.00; found, 5.51.
[
125I]-PYY (100 pM) was used as the radioligand in a total
2-[4-(2-Oxo-4H-benzo[d][1,3]oxazin-1-yl)piperidin-1-
yl]-N-(9-oxo-9H-fluoren-4-yl)acetamide Hydrochloride
(6m). Following the procedure described for the synthesis of
5a, compound 6m was prepared from 1-piperidin-4-yl-1,4-
incubation volume of 200 µL (protein concentration was 40 µg/
mL). Following incubation at 25 °C for 2 h, the reaction was
stopped by addition of 5 mL of ice-cold buffer (Tris-HCl 25 mM,
NaCl 120 mM, KCl 5 mM, KH2PO4 1.2 mM, CaCl2 2.5 mM,

Synthesis of Benzoxazinone Derivatives
Journal of Medicinal Chemistry, 2005, Vol. 48, No. 6 2091
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Food Intake Measurements. Male Wistar rats (200-270
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To study the acute effects of selected compounds on food
intake in fasted rats, animals were fasted for 23 h in home
cages, and after this period, either vehicle or selected com-
pounds were administered intraperitoneally. One hour later
preweighed food was left on top covers and cumulative food
consumption was measured 1, 2, 4, and 6 h later.
Acknowledgment. We thank the following people
for their accurate experimental work: Magda Bordas
and Miguel AÄ ngel Bla´zquez for spectroscopic data,
Carme Calvet for analytical contribution, and Sandra
Silvestre for elemental analysis collaboration.
Supporting Information Available: Results from el-
emental analysis. This material is available free of charge via
the Internet at http://pubs.acs.org.
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