Dual PPAR-α and -γ activators derived from novel benzoxazinone containing thiazolidinediones having antidiabetic and hypolipidemic potential

Article abstract of DOI:10.1016/j.bmc.2005.08.043

2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their PPAR-α and -γ dual activation. DRF-2519, a compound obtained through SAR of TZD derivatives of benzoxazinone, has shown potent dual PPAR activation. In ob/ob mice, it showed better efficacy than the comparator molecules. In fat fed rat model, it showed significant improvement in lipid parameters, which was better than fibrates.

Full text of DOI:10.1016/j.bmc.2005.08.043

Bioorganic & Medicinal Chemistry 14 (2006) 584–591
Dual PPAR-a and -c activators derived from novel
benzoxazinone containing thiazolidinediones having
antidiabetic and hypolipidemic potentialq
b,
a
a
Gurram R. Madhavan,a,* Ranjan Chakrabarti, K. Anantha Reddy, B. M. Rajesh,
*
V. Balraju,a P. Bheema Rao,a R. Rajagopalanb and Javed Iqbala
aDiscovery Chemistry, Dr. ReddyÕs Laboratories Ltd., Bollarum Road, Miyapur, Hyderabad 500049, India
bDiscovery Biology, Dr. ReddyÕs Laboratories Ltd., Bollarum Road, Miyapur, Hyderabad 500049, India
Received 6 July 2005; revised 18 August 2005; accepted 19 August 2005
Available online 28 September 2005
Abstract—2,4-Thiazolidinedione derivatives of 1,3-benzoxazinone were synthesized and evaluated for their PPAR-a and -c dual
activation. DRF-2519, a compound obtained through SAR of TZD derivatives of benzoxazinone, has shown potent dual PPAR
activation. In ob/ob mice, it showed better efficacy than the comparator molecules. In fat fed rat model, it showed significant
improvement in lipid parameters, which was better than fibrates.
ꢀ 2005 Elsevier Ltd. All rights reserved.
1. Introduction
TZDs have only marginal effect on lipids. It was visual-
ized that a dual PPAR-a and -c activator could be an
effective drug for insulin resistance, hyperglycemia,
and dyslipidemia. Several drugs of such dual activity
were in clinical development, for example, Ragaglitazar
(Dr. ReddyÕs group), KRP-297 (Kyorin), Tesaglitazar
(Astra), and Muraglitazar (BMS).6 Unfortunately, the
first two were discontinued following instances of
carcinogenicity in rodent models. NDA has recently
been filed for Muraglitazar. Interestingly, among all
these molecules, only KRP-297 is a TZD, others belong
to different chemical classes. In our thiazolidinedione
program, we synthesized a series of benzoxazinone
heterocycle derivatives of thiazolidinediones and discov-
ered a compound (DRF-2519) which exhibited potent
dual PPAR-a and -c activity. It showed significant anti-
diabetic and lipid lowering activities, which was better
than the standard drugs.
Success of thiazolidinediones (TZDs), the ligand of per-
oxisome proliferator-activated receptor c (PPARc), has
generated a lot of interest for PPARs as target for new
drug discovery. PPARs exist in three subtypes1 viz., a,
c, and d. PPAR-a is reported to be involved primarily
in hepatic lipid metabolism. Lipid lowering drug
fibrates are the ligands for PPAR-a.2 PPAR-c plays a
central role in adipogenesis and glucose homeostasis,
and as mentioned, antidiabetic drug TZDs are the
synthetic ligands for PPAR-c.3 PPAR-d is believed to
be involved in lipid metabolism, energy homeostasis,
and atherosclerosis.4 To date, no PPAR-d ligand is
available in the market. Thiazolidinediones, the first
insulin sensitizers to be marketed, decrease glucose
levels while simultaneously reducing circulating insulin
and free fatty acids.5 A large number of type II diabetes
patients also suffer from dyslipidemia. Unfortunately,
O
O
O
O
S
O
S
O
N
N
O
H
N
O
N
H
F3C
Na
O
Keywords: PPAR; TZD; Knoevenagel condensation; Plasma glucose;
Lipids.
DRF-2519
KRP-297
S
I
DRL publication No. 453-A.
Corresponding authors. Tel: +91 40 23045439; fax: +91 40
O
O
*
N
H
N
N
O
2304543; e-mail addresses: madhavangr@rediffmail.com (G.R.M);
ranjanchakrabarti@drreddys.com (R.C)
Rosiglitazone
0968-0896/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2005.08.043

G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
585
2. Chemistry
dione in a similar manner as given in Scheme 1 to give
compounds 10(a–c) [Scheme 2]. Preparations of com-
pounds linking from 2-position of benzoxazinones (13a
and b) were carried out by condensation of N-alkyl sal-
icylamide (11a and b) with the 5-[4-[2,2-diethoxy]phe-
nylmethyl]thiazolidinedione (12) in the presence of
PPE (Scheme 3), in a manner similar to that in the case
of preparation for the compounds in Scheme 1.
Compounds 1–5 were synthesized as described in
Scheme 1. The starting material, 3-(2-hydroxyethyl)-
2H-1,3-benzoxazin-4(3H)-one 17, was reacted with 4-flu-
orobenzaldehyde under SN2 conditions to give rise to
the aldehyde 2. The aldehyde was condensed with 2,4-
thiazolidinedione following Knoevenagel reaction con-
ditions.8 The unsaturated compound 3 was converted
to its saturated compound 4 under hydrogenation con-
ditions by using excess Pd/C to avoid the effect of cata-
lyst poisoning. To have better physical properties like
solubility in water and high melting point, compound
4 was converted to its sodium salt 5.
3. Results and discussion
Initially the unsaturated TZD compounds 3, 10a–c were
synthesized and assessed for their PPAR-a and -c trans-
activation, compound 3 showed moderate activity for
PPAR-a and mild activity for PPAR-c. Compound
10a which is a 2-ethyl derivative of benzoxazinone
showed no PPAR-a activity and only mild PPAR-c
activity. The propyl derivative (compound 10b) lost even
the PPAR-c activity considerably. Then we changed the
2-position substitution to phenyl group which too did
2-Substituted 1,3-benzoxazinones were synthesized from
salicylamide and aldehydes, by dehydration reaction
using PPE in refluxing chloroform. Subsequently, the
1,3-benzoxazinones were N-alkylated with 4-(2-bromo-
ethoxy)benzaldehyde to produce aldehydes 9(a–c).
These aldehydes were condensed with thiazolidine-2,4-
O
O
OH
N
(i)
O
(ii)
N
O
O
CHO
1
2
S
S
O
O
O
O
O
O
O
O
(iii)
N
N
N
H
N
H
O
O
4
3
(iv)
S
N
O
O
O
N
O
Na
O
5
DRF-2519
Scheme 1. Reagents and conditions: (i) 4-fluorobenzaldehyde, NaH, DMF, rt, 3 h, 75%; (ii) 2,4-thiazolidinedione, PhCO2H, piperidine, tolune,
reflux, 2 h, 86%; (iii) H2, Pd/C, dioxane, rt, 60 h, 74%; (iv) NaOMe, MeOH, rt, 0.5 h, 77%.
O
O
O
O
(v)
(vi)
NH2
OH
NH
R1
R1
H
+
7
6
8(a-c)
R1=a)Et,b)n-Pr, c) Ph
S
O
O
O
O
O
O
O
CHO
(ii)
N
N
H
N
O
R1
R1
10(a-c)
9(a-c)
Scheme 2. Reagents and conditions: (v) PPE, CHCl3, reflux, 6 h, 60–90%; (vi) 4(2-bromoethoxy)benzaldehyde, K2CO3, DMF, rt, 5 h, 40%.

586
G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
CHO
CHO
OEt
vii
viii
Br
+
EtO
EtO
HO
O
OEt
O
9d
S
S
x
O
ix
EtO
O
N
H
O
EtO
N
H
O
O
OEt
O
OEt
12
NHR2
OH
10d
R2=H=11a
R2=CH3=11b
O
R2
S
N
O
O
N
H
O
O
R2 =H (13a) , CH (13b)
3
Scheme 3. Reagents and conditions: (vii) NaH, DMF, 25–60 ꢁC, 48 h, 58%; (viii) 2,4-thiazolidinedione, PhCO2H, piperidine, tolune, reflux, 2 h, 70%;
(ix) H2, 10% Pd/C, dioxane, 60 psi, 60 h, 67%; (x) PPE, CHCl3, reflux, 3 h, 81%.
not improve PPAR-a; but this compound (10c) did
show PPAR-c activity. Among the four compounds,
as 3 showed moderate PPAR-a along with mild
PPAR-c activity we converted it to its saturated version
(compound 4). We knew from our previous work on
thiazolidinediones9 that saturated version of TZDs
shows a better profile as compared to their unsaturated
versions. The compound 4 showed potent PPAR-a and -
c activity. The compound 4 was converted to its sodium
salt (5, DRF-2519) to have better solubility. We did not
attempt to make the saturated TZDs of 10a–c as their
in vitro potency was less than that of compound 3.
Then, the linker attachment was changed to 2-position
of the 1,3-4(3H)benzoxazinone ring by synthesizing
compounds 13a and b, and we found that they have less
PPAR activity as compared to DRF-2519. Compound
13a showed significantly reduced PPAR-c activity, while
retaining the PPAR-a activity. Compound 13b lost even
the PPAR-a activity considerably (Table 1). There was
no significant PPAR-d activity observed for any of these
compounds. Finally, among all the compounds
DRF-2519 was selected for profiling in animal models.
there is no such concern for PPAR-c. No significant
difference in body weight change was observed in
DRF-2519 treated groups compared to control,
although PPAR-c agonist Rosi showed increase in
body weight. These data suggested that DRF-2519
due to its dual PPAR-a and -c modulating effects in vi-
vo showed significant glucose, lipid, and insulin lower-
ing activity. For further confirmation of effects on lipid
parameters, it was tested in high fat fed rat model at 3
and 10 mg/kg/day dose and showed significant reduc-
tion in TG, total cholesterol, and LDL-cholesterol,
and increase in HDL-cholesterol (Table 3), indicating
that DRF-2519 had considerable effect on the lipid
parameters. Effect of DRF-2519 (10 mg/kg) was com-
parable to that of Fenofibrate (30 mg/kg). Fenofibrate
did not show any significant effect below 30 mg/kg
dose. Standard PPAR-c activators-rosiglitazone or
pioglitazone did not show any significant activity in
this model (data not shown). It is interesting to note
that although PPAR-c activity of DRF-2519 was less
than that of Rosi, in vivo effect of DRF-2519 was bet-
ter than that of Rosi. We believe, PPAR-a activity of
DRF-2519 is also contributing to its overall activity.
The pharmacokinetic studies did not show any signifi-
cant difference in pharmacokinetic profiles of DRF-
2519 and rosiglitazone, which indicates that the differ-
ent pharmacodynamic effects of these two molecules
were not caused by any pharmacokinetic issue. Based
on the in vitro and in vivo results, DRF-2519 was
selected for further development.
From the in vitro dose–response curves of DRF-2519
(Fig. 1) for PPAR-a and -c, it was clear that DRF-
2519 was almost equally potent for PPAR-a compared
to the standard compound WY 14,643; but the potency
for PPAR-c was less compared to rosiglitazone (Rosi).
Ob/ob mice are a well-established model for obese
insulin resistance, hyperglycemia, and dyslipidemia.10
DRF-2519 administered orally in ob/ob mice showed
a dose-dependent reduction in plasma glucose (PG),
triglyceride (TG), free fatty acids (FFA), and insulin
levels after 14 days of treatment. ED50 values were cal-
culated and compared with those of Rosi and KRP-
297 (Table 2). DRF-2519 showed better efficacy than
the standard compounds. It is relevant to note that
KRP has a low affinity for murine PPAR-a,11 though
4. Conclusions
SAR studies of thiazolidinedione derivative of benzox-
azinones were carried out by synthesizing TZDs from
Knoevenagel conditions followed by hydrogenation of
the double bond. We have identified DRF-2519 as a

G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
Table 1. SAR of the thiazolidinedione derivatives of benzoxazinones
587
S. No.
Compound
number
Structure
PPAR
a (50 lM)
c (1 lM)
1
3
1.7
7.0
O
S
O
O
O
O
N
N
N
H
O
O
O
O
2
10a
0.9
6.7
S
N
H
O
O
3
4
10b
10c
1.0
1.0
3.6
8.0
S
O
O
O
O
N
N
N
H
O
O
O
O
S
N
H
O
O
5
6
4
5
4.2
5.0
36
S
O
O
O
O
N
N
H
O
O
O
O
34
S
N
N
O
O
Na
7
8
13a
13b
3.7
1.5
19.6
S
NH
O
O
O
O
N
H
O
O
O
O
20
S
N
N
H
O
9
10
WY-14643
Rosiglitazone
4.5
—
—
46.0
HEK 293T cells were transfected with PPAR-c and PPAR-a constructs as mentioned in Section 5. These values are an average of three experiments
conducted in triplicate.
potent dual PPAR-a and -c activator. It showed signif-
icant plasma glucose, insulin, and lipid lowering activity
in ob/ob mice, which was better than those of the stan-
dard compounds. Additionally, it also showed signifi-
cant improvement in lipid parameters in fat fed rats,
which was better than that of fibrate.
experimental protocols were approved by DRF Animal
Ethics Committee.
C57 BL/6J-ob/ob mice were obtained from Jackson
Laboratory, USA. They were used at the age of 10
weeks, DRF-2519, rosiglitazone, and KRP-297 were
administered orally for 14 days at 0.3, 1, 3, and 10 mg/
kg/day. All compounds were triturated to fine particles,
before making suspension. Animals in the control group
received vehicles only (0.25% CMC, 10 ml/kg). Blood
samples were collected from animals (in fed state) under
mild ether anesthesia from retro-orbital sinus 1 h after
drug administration. Plasma samples were separated
for glucose, triglycerides, and insulin measurement.
Sprague–Dawley rats were bred at Dr. ReddyÕs Labora-
tories, Discovery Research Animal House Facility. All
animals were maintained under 12 h light and 12 h dark
5. Experimental
5.1. Animals and treatment
All animals were maintained under 12 h light and 12 h
dark cycle at 25 1 ꢁC. All animals were given standard
chow (National Institute of Nutrition, India) and water
ad libitum. All animal experiments were carried out in
accordance with internationally valid guidelines. All

588
G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
taining 2% cholesterol and 1% sodium cholate mixed
PPAR-α Transactivation
with standard Laboratory chow. Hyperlipedemic Spra-
gue–Dawley rats were treated orally with DRF-2519
for 6 days. Plasma samples were separated for lipid mea-
surement. All plasma parameters were measured in
Merck vitalab autoanalyzer. Plasma insulin was mea-
sured with a rodent RIA kit from LINCO research
(USA). Blood samples were collected in fed state from
the animals under mild ether anesthesia from retro-orbi-
tal sinus, 1 h after drug administration.
80
70
60
50
40
30
20
10
0
Wy 14643
DRF 2519
5.2. PPAR transactivation assay
The response element, upstream activated sequence of
galactose DNA binding domain yeast transcription fac-
tor (UASGAL4 · 5) is present upstream of pFR-Luc
reporter (Promega, Madison, USA) that contains simian
virus early promoter for luciferase assay. GAL4 fusions
were made by fusing human PPAR-c or PPAR-a ligand
binding domain (amino acids: 174–475) to the C-termi-
nal end of the yeast GAL4 DNA binding domain (ami-
no acids: 1–147) of pM1 vector. pAdvantage (Promega)
vector was used to enhance luciferase expression. HEK
293T cells were transfected with relevant plasmids by
superfect as per the supplierÕs instruction manual.
Forty-two hours after transfection, cells were treated
for 18 h with the test compounds. DMSO (1:1000) was
used as blank. Luciferase activity was determined as fold
activation relative to untreated cells by using Luclite kit
(Packard Instrument Co, Meriden, CT, USA) in a Pack-
ard Top Count (Packard Instrument Co.).
1
10
100
Concentration (µM)
PPAR-γ Transactivation
120
100
80
60
40
20
0
Rosiglitazone
DRF 2519
5.3. Synthesis
Melting points were determined with a Veego melting
point apparatus and are uncorrected. Infrared spectra
were recorded on a Perkin–Elmer FT-IR 1600 spectro-
meter. Proton nuclear magnetic resonance (1H NMR)
spectra were recorded on a Varian Gemini 200 MHz
spectrometer with TMS as the internal standard. Mass
spectra were recorded on a HP-5989A mass spectrome-
ter. Column chromatography was performed by using
silicagel (200–400 mesh, SRL) with the indicated sol-
vent. 4-(2-Bromo ethoxy) benzaldehyde12 was prepared
according to the general method.
0.01
0.1
1
10
100
Concentration (µM)
Figure 1. PPAR-a and -c transactivation of DRF-2519. PPAR
activation was carried out as mentioned in Section 5. Fourfold
activation by WY 14643 at 25 lM and 87-fold by rosiglitazone at
25 lM has been considered as maximum effect of PPAR-a and -c,
respectively. Values are expressed as means SE from three experi-
ments conducted in triplicate.
5.3.1. Preparation of 2-ethyl-3,4-dihydro-2H-benzo[1,3]-
oxazaine-4-one (8a). To a stirred solution of PPE (6.62 g,
15.32 mmol) was added a suspension of salicylamide
(2 g, 14.6 mmol) in 20 ml of dry chloroform, followed
by a solution of propionaldehyde (1.20 ml, 16.05 mmol)
in 5 ml chloroform. The mixture was refluxed for a peri-
od of 4 h (reaction monitored by TLC). Chloroform was
evaporated completely and the residue was cooled, made
alkaline by using 10% aqueous NaOH solution to pH
10, when a cream-colored solid precipitated out. The
solid was filtered off and washed with water and pet.
ether to afford the title compound as a solid. Yield:
2.08 g (81%); mp: 108–110 ꢁC; 1H NMR (200 MHz,
CDCl3): d 7.95–7.91 (m, 1H), 7.50–7.41 (m, 1H), 7.13–
7.00 (m, 1H), 6.97 (d, J = 7.50 Hz, 1H), 5.28–5.22 (m,
1H), 2.05–1.90 (m, 2H), 1.13 (t, J = 7.50 Hz, 3H);
IR (KBr): 1683, 3405 cmÀ1; CIMS (m/z): 178 (M+H)+.
Table 2. Comparative effects of DRF-2519 with rosiglitazone in ob/ob
mice
Plasma
parameters DRF-2519
ED50 (mg/kg) for ED50 (mg/kg) ED50 (mg/kg)
for rosiglitazone for KRP-297
PG
TG
1.2
1.5
2.0
1.1
3.6
10
>10
5.0
3
10
10
8
FFA
Insulin
ED50 was calculated according to the regression analysis of the dose–
response curve.
cycle. All animals were given standard Laboratory chow
and water ad libitum. Male SD rats weighing 180–200 g
were made hyperlipidemic by feeding a high fat diet con-

G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
Table 3. Effects of DRF-2519 on high fat fed Sprague–Dawley rats
589
Group
TG (mg/dl)
TC (mg/dl)
HDL (mg/dl)
LDL (mg/dl)
297 58
Control
116 18
59 2.8*
38 4*
49 4*
342 59
226 11*
168 25*
177 15*
22
24
2
4
DRF-2519 (3 mg/kg/day)
DRF-2519 (10 mg/kg/day)
Fenofibrate (30 mg/kg/day)
184
7
32 2*
80 3*
132 10*
130 11*
Male Sprague–Dawley rats were made hyperlipidemic as mentioned in Section 5. Compounds were given for 6 days at respective doses. Values are
expressed as means SE (n = 5 per group). TG, triglyceride; TC, total cholesterol; HDL, high density lipoprotein; LDL, low density lipoprotein.
* p < 0.05 as compared to control group (ANOVA).
In the same manner, the following compounds were
obtained.
1H NMR (200 MHz, CDCl3): d 9.88 (s, 1H), 7.94–7.85
(m, 1H), 7.82 (d, J = 6.71 Hz, 2H), 7.48–7.39 (m, 1H),
7.11–6.92 (m, 4H), 5.42–5.36 (m, 1H), 4.38–4.22 (m,
3H), 3.67–3.60 (m, 1H), 2.07–1.82 (m, 2H), 1.03 (t,
J = 7.35 Hz, 3H); IR (neat): 1662, 1601 cmÀ1; CIMS
(m/z): 326 (M+H)+.
5.3.2. Preparation of 2-propyl-3,4-dihydro-2H-benzo[1,3]-
1
oxazaine-4-one (8b). Yield: 75%; mp: 98 ꢁC; H NMR
(200 MHz, CDCl3): d 7.95–7.91 (m, 1H), 7.50–7.41 (m,
1H), 7.14–7.05 (m, 1H), 6.97 (d, J = 8.30 Hz, 1H),
5.33–5.26 (m, 1H), 2.03–1.90 (m, 2H), 1.86–1.62 (m,
2H), 1.02 (t, J = 7.35 Hz, 3H); IR (KBr): 3470, 1683,
1469 cmÀ1; CIMS (m/z): 192 (M+H)+.
Following aldehydes were prepared in a similar manner
mentioned above.
5.3.6. Preparation of 4-[2-(2-propyl-4-oxo-3,4-dihydro-
5.3.3. Preparation of 2-phenyl-3,4-dihydro-2H-benzo[1,3]-
oxazaine-4-one (8c). Yield: 68%; mp: 166–167 ꢁC; 1H
NMR (200 MHz, CDCl3): d 8.00–7.95 (m, 1H), 7.6–
7.51 (m, 2H), 7.49–7.42 (m, 4H), 7.18–7.10 (m, 1H),
6.98 (d, J = 8.06 Hz, 1H), 6.58 (br s, 1H), 6.25 (s, 1H);
IR (KBr): 3186, 1685, 1610, 1467 cmÀ1; CIMS (m/z):
225 (M+H)+.
2H-benzo[1,3]oxazin-3-yl)ethoxy]benzaldehyde
(9b).
Yield: 30%; 1H NMR (200 MHz, CDCl3): d 9.87 (s,
1H), 7.94–7.89 (m, 1H), 7.85–7.78 (m, 2H), 7.52–7.35
(m, 1H), 7.14–6.86 (m, 4H), 5.51–5.44 (m, 1H),
4.40–4.19 (m, 3H), 3.68–3.55 (m, 1H), 1.90–1.70 (m,
2H), 1.57–1.3 (m, 2H), 1.02 (t, J = 7.35 Hz, 3H); IR
(neat): 1663, 1601, 1471 cmÀ1
(M+H)+.
; CIMS (m/z): 340
5.3.4. Preparation of 4-[2-(4-oxo-3,4-dihydro-2H-
benz[1,3]oxazin-3-yl)ethoxy]benzaldehyde (2). To an ice-
cold stirred solution of 3-(2-hydroxyethyl)-2H-1,3-benz-
oxazin-4(3H)one4 (0.5 g, 2.59 mmol) in dry DMF (5 ml)
was added portionwise NaH (60%). After stirring for
10 min at room temperature, 4-fluorobenzaldehyde
(0.35 g, 2.85 mmol) was added dropwise at 0 ꢁC. The
reaction was stirred at room temperature for 3 h and
quenched by adding ice pieces when a cream colored sol-
id separated out, which was filtered, washed with water,
and dried to afford the title product. Yield: 0.58 g
5.3.7. Preparation of 4-[2-(2-phenyl-4-oxo-3,4-dihydro-
2H-benzo[1,3]oxazin-3-yl)ethoxy]benzaldehyde (9c).
Yield: 20%; 1H NMR (200 MHz, CDCl3): d 9.89 (s,
1H), 9.33 (d, J = 8.81 Hz, 1H), 8.23 (d, J = 8.81 Hz,
1H), 7.83 (d, J = 7.79 Hz, 2H), 7.75 (d, J = 9.72 Hz,
1H), 7.59 (t, J = 5.58 Hz, 2H), 7.43–7.29 (m, 3H),
7.00–6.50 (m, 3H), 6.51 (m, 1H), 4.44–4.34 (m, 4H);
IR (KBr): 3390, 1676, 1600 cmÀ1; CIMS (m/z): 373
(M+).
1
(75.4%); H NMR (200 MHz, CDCl3): d 9.89 (s, 1H),
5.3.8. Preparation of 4-[(2,2-diethoxy)ethoxy]benzalde-
hyde (9d). To a stirred suspension of 98% sodium hy-
dride (2.5 g, 100 mmol) in DMF (100 ml) was added a
solution of 4-hydroxybenzaldehyde (10 g, 82 mmol) in
DMF (100 ml) slowly dropwise at room temperature
and stirred for 30 min and bromoacetaldehyde diethy-
lacetal (19.7 g, 100 mmol) was added to the reaction
mixture, and the mixture was heated at 60 ꢁC for 48 h.
The reaction mixture was cooled to room temperature,
quenched with water (200 ml), and extracted with ethyl
acetate (3·300 ml). The combined organic layers were
washed with brine, dried over sodium sulfate, and
concentrated. The crude compound was purified by
chromatography using EtOAc/pet. ether (1:2) as eluent
to yield the title compound (12.65 g, 58%) as a brown
colored liquid.
7.95 (d, J = 7.60 Hz, 1H), 7.84 (d, J = 8.62 Hz, 2H),
7.45 (t, J = 7.05 Hz, 1H), 7.12 (t, J = 7.40 Hz, 1H), 7.0
(d, J = 8.62 Hz, 2H), 6.98 (d, J = 8.07 Hz, 1H), 5.37 (s,
2H), 4.30 (t, J = 4.82 Hz, 2H), 3.99 (t, J = 4.82 Hz,
2H); IR (KBr): 1697, 1650 cmÀ1; CIMS (m/z): 297 (M+).
5.3.5. Preparation of 4-[2-(2-ethyl-4-oxo-3,4-dihydro-2H-
benzo[1,3]oxazin-3-yl)ethoxy]benzaldehyde (9a). A mix-
ture of 2-ethyl-3,4-dihydro-2H-benzo[1,3]oxazaine-4-
one (1 g, 5.64 mmol), fused K2CO3 (2.35 g, 16.94 mmol)
in 10 ml of dry DMF was stirred for a period of30 min fol-
lowed by the addition of a solution of 4-(2-bromoeth-
oxy)benzaldehyde (1.29 g, 5.64 mmol) in 5 ml of dry
DMF at room temperature. The reaction mixture was
then stirred at 70 ꢁC for a period of 24 h. The reaction
mixture was diluted with ethyl acetate (100 ml) and
washed with water (3·50 ml), brine (50 ml). The organ-
ic layer was dried over anhydrous Na2SO4, evaporated,
and chromatographed using (1:3) EtoAc/pet. ether
system to afford 30% yield of title product as a color-
less gum.
1H NMR (200 MHz, CDCl3): d 9.88 (s, 1H), 7.82 (d,
J = 8.63 Hz, 2H), 7.02 (d, J = 8.63 Hz, 2H), 4.85 (t,
J = 5.17 Hz, 1H), 4.08 (d, J = 7.17 Hz, 2H), 3.88–3.50
(m, 4H), 1.24 (t, J = 7.03 Hz, 6H); IR (neat): 1670,
1560; CIMS (m/z): 239 (M+H)+.

590
G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
5.3.9. Preparation of 5-[4-[2-[2H-1,3-benzoxazin-4(3H)
one-3-yl]ethoxy]phenylmethylene]thiazolidine-2,4-dione (3).
A mixture of 4-[2-(4-oxo-3,4-dihydro-2H-benz[1,3]oxa-
zin-3-yl)ethoxy]benzaldehyde (2.82 g, 9.49 mmol), 2,4-
thiazolidinedione (1.10 g, 9.49 mmol), benzoic acid
(0.15 g, 1.23 mmol), and piperidine (0.12 g, 1.42 mmol)
in 50 ml toluene was refluxed with continuous removal of
waterformedduringthereactionfor2 h.Thereactionmix-
ture was cooled and the yellow solid was filtered off and
dried to afford the title compound. Yield: 3.23 g, 86%;
mp: 188–190 ꢁC; 1H NMR (200 MHz, CDCl3): d 7.96 (d,
J = 7.88 Hz, 1H), 7.79 (s, 1H), 7.45 (d, J = 8.39 Hz, 2H),
7.12 (d, J = 7.47 Hz, 1H), 7.00 (d, J = 7.50 Hz, 2H), 6.99
(d, J = 8.39 Hz, 2H), 5.37 (s, 2H), 4.28 (t, J = 4.78 Hz,
2H), 3.98 (t, J = 4.78 Hz, 2H); IR (KBr): 3437, 1694,
1661 cmÀ1; CIMS (m/z): 396 (M+). Analysis calculated
for C20H16N2O5S: C, 60.65; H, 4.06; N, 7.07. Found: C,
60.45; H, 3.95; N, 7.11%.
5.78 mmol), and piperidine (0.64 ml, 6.7 mmol) in tolu-
ene (150 ml) was refluxed for 2 h under continuous
removal of water. The reaction mixture was cooled to
room temperature and diluted with EtOAc (150 ml).
The mixture was washed with water, brine, dried over
sodium sulfate, and concentrated. The crude compound
was purified by column chromatography using EtOAc/
pet. ether (1:2) as eluent to afford the title compound
(12.54 g, 70%) as a brown colored oil.
1H NMR (200 MHz, CDCl3): d 8.70 (br s, 1H, D2O
exchangeable), 7.80 (s, 1H), 7.45 (d, J = 8.72 Hz, 2H),
4.87 (t, J = 5.21 Hz, 1H), 4.08 (d, J = 5.21 Hz, 2H),
3.90–3.52 (m, 4H), 1.26 (t, J = 7.02 Hz, 6H); IR (neat):
1740, 1700, 1620 cmÀ1; CIMS (m/z): 338 (M+H)+.
5.3.14. Preparation of 5-[4-[2-[2H-1,3-benzoxazin-
4(3H)one-3-yl]ethoxy]phenylmethyl]thiazolidine-2,4-dione
(4).
A
solution of 5-[4-[2-[2H-1,3-benzoxazin-
4(3H)one-3-yl]ethoxy]phenylmethylene]thiazolidine-2,4-
dione (3.2 g, 8.08 mmol) in 75 ml of 1,4-dioxan and
10% Pd/C (8 g) was taken in a 500 ml parr hydrogena-
tion flask and hydrogenated at 60 psi for 48 h at room
temperature. The catalyst was filtered off through a
Celite bed and washed with dioxane. Combined organ-
ic layers were evaporated to afford the product, which
was crystallized from dichloromethane/hexane. Yield:
2.4 g, 74.6%; mp: 110–112 ꢁC; 1H NMR (200 MHz,
Following compounds (10a–c) and 16 were prepared in
the similar procedure mentioned above.
5.3.10. Preparation of 5-[4-[2-[2-ethyl-1,3-benzoxazin-
4(3H)one-3- yl]ethoxy]phenyl methylene]thiazolidine-2,4-
dione (10a). Yield: 79%; mp: 156–158 ꢁC; 1H NMR
(200 MHz CDCl3):
d 8.19 (br s, 1H), 7.91 (d,
J = 7.89 Hz, 1H), 7.77 (s, 1H), 7.43 (d, J = 8.63 Hz,
2H), 7.11–6.91 (m, 5H), 5.41–5.35 (m, 1H), 4.24 (t,
J = 7.90 Hz, 2H), 3.64 (t, J = 7.90 Hz, 2H), 2.02–1.88
(m, 2H), 1.03 (t, J = 7.40 Hz, 3H); IR (KBr): 1740,
1703, 1640 cmÀ1; CIMS (m/z): 425 (M+H)+. Analysis
calculated for C22H20N2O5S: C, 62.31; H, 4.75; N,
6.60. Found: C, 62.28; H, 4.76; N, 6.55%.
CDCl3):
d
7.96 (d, J = 7.56 Hz, 1H), 7.45 (t,
J = 7.20 Hz, 1H), 7.15 (d, J = 8.63 Hz, 2H), 7.08 (t,
J = 7.40 Hz, 1H), 6.95 (d, J = 7.40 Hz, 1H), 6.84 (d,
J = 8.63 Hz, 2H), 5.38 (s, 2H), 4.50 (dd, J = 9.20 and
3.87 Hz, 1H), 4.20 (t, J = 4.60 Hz, 2H), 3.97 (t,
J = 4.60 Hz, 2H), 3.44 (dd, J = 14.11 and 4.15 Hz, 1H),
3.12 (dd, J = 14.10 and 9.40 Hz, 1H); IR (KBr): 1756,
1701, 1650 cmÀ1; CIMS (m/z): 399 (M+H)+. Analysis
calculated for C20H18N2O5S: C, 60.35; H, 4.55; N,
7.04. Found: C, 60.29; H, 4.40; N, 7.02%.
5.3.11. Preparation of 5-[4-[2-[2-propyl-1,3-benzoxazin-
4(3H)one-3-yl]ethoxy]phenylmethylene]thiazolidine-2,4-
dione (10b). Yield: 81%; mp: 160–162 ꢁC; 1H NMR
(200 MHz, CDCl3): d 8.80 (br s, 1H), 7.90 (d,
J = 7.80 Hz, 1H), 7.77 (s, 1H), 7.50–7.39 (m, 3H),
7.15–6.90 (m, 4H), 5.51–5.40 (m, 1H), 4.40–4.10 (m,
4H), 3.81–3.5 (m, 2H), 2.10–1.70 (m, 2H), 0.98 (t,
J = 7.40 Hz, 3H); IR (KBr): 3035, 1745, 1703,
1641 cmÀ1; CIMS (m/z): 439 (M+H)+. Analysis calculat-
ed for C23H22N2O5S: C, 63.06; H, 4.05; N, 6.39. Found:
C, 62.83; H, 4.93; N, 6.60%.
5.3.15. 5-[4-[[4-oxo-3,4-dihydro-(2H)-1,3-benzoxazine-2-
yl]methoxy]phenylmethyl]thiazolidine-2,4-dione
(13a).
To a stirred solution of polyphosphonate ethyl ester
(PPE) (3.15 g, 7.29 mmol) in chloroform (4 ml) was
added salicylamide (0.5 g, 3.65 mmol) followed by addi-
tion of a solution of 5-[4-[(2,2-diethoxy]phenylmethyl-
ene]thiazolidine-2,4-dione (10d) (1.36 g, 4.0 mmol) in
chloroform (10 ml) dropwise at room temperature.
The reaction mixture was refluxed for 3 h, cooled to
room temperature, and CHCl3 was removed under re-
duced pressure. To the resultant residue aq saturated
NaHCO3 solution was added (25 ml) and stirred for
30 min. The precipitated brown colored solid was
filtered and purified by column chromatography by
EtOAc/pet. ether (1:1) to yield the title compound,
(1.15 g, 81%). mp: 134–138 ꢁC; 1H NMR (200 MHz,
CDCl3): d 8.40 (br s, 1H, D2O exchangeable), 7.90
(d, J = 7.50 Hz, 1H), 7.15 (d, J = 8.30 Hz, 2H), 7.05
(t, J = 7.50 Hz, 1H), 6.90 (d, J = 7.50 Hz, 1H), 6.80
(d, J = 8.30 Hz, 2H), 5.80 (t, J = 5.30 Hz, 1H), 4.42
(dd, J = 9.50, 3.80 Hz, 1H), 4.30–4.10 (m, 2H), 3.34
(dd, J = 14.10, 3.80 Hz, 1H), 3.02 (dd, J = 14.10,
9.50 Hz, 1H); IR (KBr): 1751, 1699, 1650 cmÀ1; CIMS
(m/z): 385 (m/z): 385 (M)+. Analysis calculated for
5.3.12. Preparation of 5-[4-[2-[2-phenyl-1,3-benzoxazin-
4(3H)one-3-yl]ethoxy]phenylmethylene]thiazolidine-2,4-
dione (10c). Yield: 85%; mp:170–172 ꢁC; 1H NMR
(200 MHz, CDCl3): d 9.41 (d, J = 9.60 Hz, 1H), 8.90
(br s, 1H, D2O exchangeable), 8.32 (d, J = 8.0 Hz,
1H), 7.89 (d, J = 8.0 Hz, 1H), 7.86 (s, 1H), 7.80–7.60
(m, 1H), 7.58–7.25 (m, 5H), 7.27–6.80 (m, 4H), 6.60 (s,
1H), 4.60–4.30 (m, 4H); IR (KBr): 3368, 1740, 1701,
1597 cmÀ1; CIMS (m/z): 473(M+H)+. Analysis calculat-
ed for C26H20N2O5S: C, 66.15; H, 4.26; N, 5.93. Found:
C, 65.97; H, 4.17; N, 5.99%.
5.3.13.
5-[4-[(2,2-Diethoxy)]phenyl]methylene]thiazoli-
dine-2,4-dione (10d). A mixture of 4-[2,2-diethoxy]eth-
oxy]benzaldehyde (10.6 g, 44.53 mmol), thiazolidine-
2,4-dione (5.21 g, 44.53 mmol), benzoic acid (0.7 g,

G. R. Madhavan et al. / Bioorg. Med. Chem. 14 (2006) 584–591
591
C19H16N2O5S: C, 59.42; H, 4.19; N, 7.29. Found: C,
59.39; H, 4.11; N, 7.14%.
1612, 1586 cmÀ1 ; CIMS (m/z): 398 (M+; for metal free
ligand).
5.3.16. 5-[4-[[3-Methyl-4-oxo-3,4-dihydro-(2H)-1,3-ben-
zoxazine-2-yl]methoxy]phenylmethyl]thiazolidine-2,4-di-
one (13b). This compound was prepared in a similar
manner as described for 13a starting from N-methyl sali-
cylamide. Yield: 60%; mp: 187 ꢁC; 1H NMR (200 MHz,
CDCl3): d 8.23 (br s, 1H, D2O exchangeable), 7.95
(d, J = 7.50 Hz, 1H), 7.43 (t, J = 7.50 Hz, 1H), 7.12
(d, J = 8.54 Hz, 2H), 7.08 (t, J = 5.39 Hz, 1H), 6.93 (d,
J = 7.50 Hz, 1H), 6.77 (d, J = 8.54 Hz, 2H), 5.62
(t, J = 5.39 Hz, 1H), 3.21 (d, J = 3.83 Hz, 3H), 3.10 (dd,
J = 14.05, 9.04 Hz, 1H); IR (KBr): 1757, 1702,
1646 cmÀ1; CIMS (m/z): 399 (M+H)+. Analysis calculat-
ed for C20H18N2O5S: C, 60.35; H, 4.55; N, 7.04. Found: C,
60.22; H, 4.58; N, 7.14%.
Acknowledgment
We are thankful for Dr. ReddyÕs management and the
encouragement and support provided.
References and notes
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Heyman, R. A.; Briggs, M.; Deeb, S.; Staels, B.; Auwerx,
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5.3.17. Preparation of 5-[4-[2-[2H-1,3-benzoxazin-
4(3H)one-3-yl]ethoxy]phenylmethyl]thiazolidine-2,4-dione
sodium salt (5; DRF-2519). To a stirred solution of 5-[4-
[2-[2H-1,3-benzoxazin-4(3H)one-3-yl]ethoxy]phenylmeth-
yl]thiazolidine-2,4-dione (0.65 g, 1.63 mmol) in 9 ml of
dry MeOH was added NaOMe (freshly prepared by
dissolving 150 mg sodium in 6 ml MeOH) and stirred
for 30 min. About 25 ml of dry ether was added to
the reaction mixture when a white solid separated
out, which was filtered and dried. Yield: 0.53 g,
77.3%; mp: 277 ꢁC; 1H NMR (200 MHz, CDCl3): d
7.80 (d, J = 7.50 Hz, 1H), 7.49 (t, J = 7.50 Hz, 1H),
7.18 (t, J = 7.50 Hz, 1H), 7.09 (d, J = 8.53 Hz, 2H),
7.05 (d, J = 7.50 Hz, 1H), 6.84 (d, J = 8.53 Hz, 2H),
5.40 (s, 2H), 4.11 (t, J = 5.39 Hz, 2H), 4.03 (dd,
J = 10.47 and 3.33 Hz, 1H), 3.84 (t, J = 5.39 Hz, 2H),
3.33 (dd, J = 14.02 and 3.33 Hz, 1H), 2.60 (dd,
J = 14.02 and J = 10.47 Hz, 1H); IR (KBr): 1666,
8. Johnson, J. R. Org. React. 1942, 1, 210.
9. Madhavan, G. R.; Chakrabarti, R.; Vikramadithyan, R.
K. V.; Rao, N. V. S. M.; Balaraju, V.; Rajesh, B. M.;
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