New oxadiazolidinedione derivatives as potent and selective human β3 agonists

Article abstract of DOI:10.1016/S0960-894X(01)00147-0

As part of our investigation into the development of potent and selective human β₃ agonists, a series of thiazolidinedione analogues was prepared and evaluated for their biological activity on the human β₃-adrenergic receptor. The oxadiazolidinedione derivative 17 was found to be the most potent and selective compound in this study, with an EC₅₀ value of 0.02μM at the β₃ receptor, 259-fold selectivity over the β₁ receptor, and 745-fold selectivity over the β₂ receptor.

Full text of DOI:10.1016/S0960-894X(01)00147-0

Bioorganic & Medicinal Chemistry Letters 11 (2001) 981–984
New Oxadiazolidinedione Derivatives as Potent
and Selective Human ꢀ3 Agonists
Baihua Hu,a,* Michael Malamas,b John Ellingboe,a Elwood Largis,c
Stella Han,c Ruth Mulveyc and Jeff Tillettc
aChemical Sciences, Wyeth-Ayerst Research, Pearl River, NY 10965, USA
bChemical Sciences, Wyeth-Ayerst Research, PO Box CN-800, Princeton, NJ 08543, USA
cCardiovascular/Metabolic Diseases Research, PO Box CN-800, Princeton, NJ 08543, USA
Received 11 January 2001; accepted 9 February 2001
Abstract—As part of our investigation into the development of potent and selective human b3 agonists, a series of thiazolidinedione
analogues was prepared and evaluated for their biological activity on the human b3-adrenergic receptor. The oxadiazolidinedione
derivative 17 was found to be the most potent and selective compound in this study, with an EC50 value of 0.02 mM at the b3
receptor, 259-fold selectivity over the b1 receptor, and 745-fold selectivity over the b2 receptor. # 2001Elsevier Science Ltd. All
rights reserved.
Potent and selective b3-adrenergic receptor (b3-AR)
agonists are potential drugs for the treatment of obesity,
type II diabetes, frequent urination, and related dis-
eases.1 Any b1-AR or b2-AR-agonism would likely
cause increased heart rate or muscle tremor, respec-
tively; both are unacceptable side effects in a drug. In a
previous paper, 2,4-thiazolidinedione derivative 1 was
reported as a potent and selective human b3-AR ago-
nist,2 with an EC50 value of 0.01 mM, >110-fold selec-
tivity over both the b1- and b2-ARs, and active and
selective in in vivo procedures. The previous structure–
activity relationship study on the left-hand side of gen-
eral structure 2 revealed that the combination of 4-
hydroxy and 3-methylsulfonamide on the phenyl ring
was necessary for the thiazolidinedione based b3 ago-
nist’s activity and selectivity. Herein we report further
modification on 2 by introducing a variety of thiazoli-
dinedione replacements, leading to the discovery of
oxadiazolidinedione derivative 17 as a potent and selec-
tive human b3 agonist.
The thiazolidinedione analogues described in this paper
were readily prepared by utilizing reductive amination
of piperidones with left-hand side amines2 according to
the synthetic Schemes 1–3. The thiazolidineones,
hydantoins, and pseudothiohydantoins (8, 10, and 13)
were prepared according to Scheme 1. A Knoevenagel
condensation between aldehyde 33 and 2,4-thiazolidine-
dione (4a), pseudothiohydantoin (4b) or hydantoin (4c)
followed by acidic hydrolysis provided piperidones 6.
Reductive aminations between piperidones 6 and amine
7 gave the olefines (8). Compound 5 was converted to 9
by a hydrogen transfer reaction (5% sodium mercury
amalgam) followed by an acidic ketal hydrolysis. Reduc-
tive amination of 9 with 7, as described above, gave the
reduced analogue 10. Alkylation of thiazolidinedione 9a2
(the substituents a–c for compounds 4, 5, 6, and 9 are
defined to be the same as those defined for compound 8)
with t-butyl bromoacetate followed by reductive ami-
nation with 12 and acid hydrolysis produced 13.
Oxadiazolidinedione 17 was prepared as outlined in
Scheme 2. Reductive amination of 3 with hydroxylamine
produced 14, which upon treatment with N-TMS isocy-
anate and ketal hydrolysis afforded hydroxyurea 15.
The oxadiazolidinedione ring was formed by reacting
the N-hydroxyurea 15 with methyl chloroformate and
sodium hydride.4 The final product 17 was obtained by
reductive amination of 16 with 12 using essentially the
same conditions as previously described in Scheme 1.
Synthesis of thiazolidinones (20, 22, and 23) was
achieved as illustrated in Scheme 3. The thiazolidinone
*Corresponding author. Tel.:+1-845-732-5773; fax: +1-845-732-
5561; e-mail: hub@war.wyeth.com
0960-894X/01/$ - see front matter # 2001Elsevier Science Ltd. All rights reserved.
PII: S0960-894X(01)00147-0

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B. Hu et al. / Bioorg. Med. Chem. Lett. 11 (2001) 981–984
Scheme 1. (a) Piperidine, EtOH; (b) concd HCl; (c) NaBH(OAc)3, DMF; (d) 5% Na/Hg, THF/H2O; (e) concd HCl; (f) 7, NaBH(OAc)3, DMF; (g)
t
BrCH2CO2 Bu; NaH, DMF, 76%; (h) 12, NaBH(OAc)3, DMF, 68%; (i) TFA, CH2Cl2, 58%.
19b (the substituents for compounds 19a–e are defined
to be the same as those defined for compound 20) was
obtained by condensation of rhodanine 5d with
hydroxylamine in refluxing ethanol and ketal hydrolysis.
Alternatively, alkylation of rhodanine 5d with iodo-
methane provided the methylmercapto compound 18.
Reaction of compound 18 with various amines such as
piperidine, 4-amino-1-benzylpiperidine, N,N-dimethyl-
guanidine or cyanamide followed by ketal hydrolysis
gave the desired intermediates 19a and 19c–e. Conver-
sion of 19 to the final olefinic thiazolidinones (20, 22,
and 23) was accomplished according to Scheme 1. In all
cases of the Knoevenagel condensation, only the Z iso-
mer was obtained for the olefinic product.5
Scheme 2. (a) NH2OH HCl salt, NaOAc, 90%; (b) NaCNBH3,
MeOH, 78%; (c) Me3SiNCO, THF/dioxane (1:1), 73%; (d) concd
HCl, 98%; (e) ClCO2Me, NaH, THF; (f) NaH, DMF, 85% over e and
f; (g) 12, NaBH(OAc)3, DMF, 71%.
The thiazolidinedione derivatives and related com-
pounds were tested for their in vitro activity in stimu-
lating an increase in cAMP levels in Chinese hamster
Scheme 3. (a) NaOAc, AcOH, 66%; (b) MeI, N,N-diisopropylethylamine, EtOH, 99%; (c) NHR1R2, EtOH; (d) concd HCl; (e) 12, NaBH(OAc)3,
DMF; (f) NaBH(OAc)3, DMF.

B. Hu et al. / Bioorg. Med. Chem. Lett. 11 (2001) 981–984
983
ovary (CHO) cells expressing the human b3-, b2-, and
b1-ARs6 and the results are summarized in Tables 1and
2. The olefinic thiazolidinedione 8a was found to be as
potent (b3 EC50=0.006 mM, IA=1.03)7 and selective
(96-fold vs b2 and 492-fold vs b1) as 1. The correspond-
ing olefinic pseudothiohydantoin 8b and hydantion 8c,
although having comparable agonist activity, were less
selective against the b2 (61- and 18-fold, respectively)
and b1 (113- and 38-fold, respectively) receptors. The
reduced alkyl analogues 10a and 10b showed reduced b3
potency (EC50=0.09 and 0.23 mM, respectively). Repla-
cement of thiazolidinedione with oxadiazolidinedione
(17) gave good potency (EC50=0.02 mM, IA=1.0) at
the b3 receptor and increased selectivity against the b1
(259-fold) and b2 receptors (745-fold).
selectivity of 20d and 20e, two more series of thiazolidi-
nones with phenoxypropanolamines2 on the left-hand
side were synthesized. In contrast to phenethanolamines
20a–e, all of the tested phenoxypropanolamines (22 and
23) had no measurable b2 agonist activity. For both the
guanidine and piperidine series, many potent b3-ago-
nists were identified, including compounds with a car-
bostyril (22b and 23b), benzimidazolone (22a and 23a),
or 4-OH-3-methylsulfonamide phenyl (23e) substituent.
However, only benzimidazolones (22a and 23a) dis-
played a good b3 agonist selectivity profile. The guani-
dines with a phenoxy (22c) or 4-hydroxyphenoxy (22d)
substituent had low potency at the b3 receptors with
EC50’s of 0.94 and 0.4 mM, respectively.
Selected compounds with good agonist activity/selectiv-
ity profiles were examined in b1 and b2-AR binding
assays (Table 3).9 Benzimidazolone 22a exhibited strong
antagonist activity against both b1 and b2 receptors with
binding constants (Ki) of 0.0038 mM for b2 and
0.0072 mM for b1. In contrast, compounds 13 and 17
exhibited low binding affinity (Ki >2 mM) for both b2
and b1 receptors, suggesting good selectivity for the b3
receptor.
Results from our earlier chemical series demonstrated
that introduction of a carboxylic acid group on the
right-hand side of 2-(1-phenyl-piperidin-4-ylamino)-
ethanol b3 agonists would enhance selectivity while
maintaining the b3 agonist activity.8 Introducing a car-
boxylic acid group to 1 did enhance the b2 selectivity.
However, the activity of 13 was decreased 3-fold relative
to 1.
A variety of thiazolidinones with different substitution
on the thiazolidinone ring were tested, some of which
are shown in Tables 1and 2. Thiazolidinones with a
cyanamide (20a), hydroxylamine (20b) or 4-amino-1-
benzylpiperidine (20c) substituent were generally very
potent at the b3 receptor (with EC50’s of single digits
nM and maximal activation 83–122% of that evoked by
isoproterenol), however, they were not very selective
against both the b2 and b1 receptors. Further modifica-
tion of the substitution on the right-hand side of thia-
zolidinones led to guanidine 20d and piperidine 20e,
which were found to be potent at the b3 receptor (with
EC50’s of 0.003 and 0.009 mM, respectively) and moder-
ately selective (73- to 423-fold) against the b2 and b1
receptors. In view of the potent activity and modest
The ability of b3 agonist 17 to treat or inhibit disorders
related to obesity or type II diabetes was confirmed in
an in vivo procedure,10 which measured thermogenesis
in human b3 AR-transgenic mice (Tg mice). Adminis-
tered 10 mg/kg (ip) to Tg mice, 17 produced a sig-
nificant effect (30Æ8%) in thermogenesis.
There have been a number of reports that the thiazoli-
dinediones are high-affinity peroxisome proliferator-
activated receptor (PPARg) agonists, and there is a
significant positive relationship between the in vitro
Table 2. Comparison of b3-AR agonist activity and selectivity of
thiazolidineones
Compd
b3-ARa
EC50 (mM)(IA)
b2-ARa
(IA)
b1-AR
S3/1b (IA)
Table 1. Comparison of b3-AR agonist activity and selectivity of
thiazolidinediones and related analogues7
22a
22b
22c
22d
23a
23b
23c
23e
0.01(0.94)
0.002(1.0)
0.94(0.79)
0.40(0.93)
0.009(0.95)
0.006(1.1)
0.075(0.96)
0.001(1.0)
(0)
(0)
(0.09)
6(0.65)
nd
b
b
Compd
b3-ARa
EC50 (mM)(IA)
S3/2
(IA)
S3/1
(IA)
ndc
nd
nd
(0.25)
(0)
(0)
(0.25)
1.7(0.79)
221(0.47)
9(0.76)
CL316243
1
8a
8b
8c
10a
10b
17
1.15(0.63)
0.01(1.19)
0.006(1.03)
0.009(1.0)
0.034(0.94)
0.086(1.2)
0.23(1.0)
227(0.43)
119(0.67)
96(0.83)
61(0.40)
18(0.38)
27(0.19)
ndc
259(0.59)
>290(0.0)
48(0.54)
28(0.86)
10(0.58)
110(0.47)
97(0.62)
97(0.21)
272(0.82)
492(0.87)
113(0.80)
38(0.82)
38(0.76)
nd
745(0.29)
86(0.56)
290(0.86)
54(0.71)
133(0.69)
423(0.82)
73(0.90)
(0)
aSee footnotes in Table 1.
bSee footnotes in Table 1.
cSee footnotes in Table 1.
0.02(1.0)
13
0.034(1.1)
0.001(1.0)
0.008(0.83)
0.009(1.22)
0.003(0.86)
0.009(1.06)
20a
20b
20c
20d
20e
Table 3. b1-AR and b2-AR binding inhibition constants (Ki)
Compd
b1-AR Bindinga
(Ki, mM)
b2-AR Bindinga
(Ki, mM)
ab-AR agonistic activities were assessed by measurement of cAMP
accumulation levels in CHO cells expressing human b-ARs; the
intrinsic activities (IA) were given as a fraction of the maximal stimu-
lation with isoproterenol.
13
17
22a
9.10
9.49
0.0038
2.10
74.0
0.0072
bAgonist selectivity for b3 over bn is defined by S3/n=bn EC50/b3 EC50
.
aBinding potency was reported as Ki (mM), the binding inhibition
cnd=not determined.
constant, determined by inhibition of 125I-iodocyanopindolol.

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B. Hu et al. / Bioorg. Med. Chem. Lett. 11 (2001) 981–984
activity at the PPARg receptor and the in vivo anti-
hyperglycemic activity in genetically diabetic mice.11
Although our compounds possess thiazolidinedione
substituents, they showed essentially no activity (data
not shown) at the PPARg receptor.
L.; Malamas, M.; Nulvey, R.; Oliphant, A.; Sum, F. W.;
Tillett, J.; Wong, V. Bioorg. Med. Chem. Lett. 2001, 11, 757.
3. Taylor, E. C.; Skotnicki, J. S. Synthesis 1981, 606.
4. Malamas, M.; Sredy, J.; Gunawan, I.; Mihan, B.; Sawicki,
D.; Seestaller, L.; Sullivan, D.; Flam, B. J. Med. Chem. 2000,
43, 995.
5. Unangst, P. C.; Connor, D. T.; Cetenko, W. A.; Sorenson,
R. J.; Kostlan, C. R.; Sircar, J. C.; Wright, C. D.; Schrier,
D. J.; Dyer, R. D. J. Med. Chem. 1994, 37, 322.
6. The human b3 receptor was cloned as described in Van, S.
A.; Nahmias, C. K. S.; Briend-Sutren, M. M.; Strosberg, A.
D.; Emorine, L. J. Eur. J. Biochem. 1993, 213, 1117. The
human b2 and b1 receptors were cloned as described in Tate,
K. M.; Briend-Sutren, M. M.; Emorine, L. J.; Delavier-
Klutchko, C.; Marullo, S.; Strosberg, A. D. Eur. J. Biochem.
1991, 196, 357.
In conclusion, the synthesis and structure–activity
relationship of thiazolidinedione based b3 agonists
have been discussed. Replacement of the 2,4-thiazoli-
dinedione group with an oxadiazolidinedione has led
to the identification of a potent and selective agonist
(17) with an EC50 of 0.02 mM, 259-fold selectivity
over b2 and 745-fold selectivity over b1. It has also
been showed to be thermogenic in human b3-AR trans-
genic mice.
7. Compounds 8a–c and 10a–b were tested as racemates (as
indicated in Scheme 1).
8. Hu, B.; Ellingboe, J.; Han, S.; Largis, E.; Lim, K.; Mala-
mas, M.; Nulvey, R.; Niu, C.; Oliphant, A.; Pelletier, J.; Sin-
ganallore, T. V.; Sum, F. W.; Tillett, J.; Wong, V. Bioorg.
Med. Chem., in press.
9. For radioligand binding procedure see: Zheng, W.; Niku-
lin, V. I.; Konkar, A. A.; Vansal, S. S.; Shams, G.; Feller,
D. R.; Miller, D. D. J. Med. Chem. 1999, 42, 2287.
10. Susulic, V. S.; Frederich, R. C.; Lawitts, J.; Tozzo, E.;
Khahn, B. B.; Harper, M.-E.; Himms-Hagen, J.; Flier, J. S.;
Lowell, B. B. J. Biol. Chem. 1995, 270, 29483.
Acknowledgements
The authors acknowledge the members of the Wyeth-
Ayerst Discovery Analytical Chemistry group for ana-
lytical and spectral determinations.
References and Notes
1. (a) For recent reviews on b3-agonists see: Weyer, C.; Gau-
tier, J. F.; Danforth, E., Jr. Diabetes Metab. 1999, 25, 11. (b)
Kordik, C. P.; Reitz, A. B. J. Med. Chem. 1999, 42, 181.
2. Hu, B.; Ellingboe, J.; Gunawan, I.; Han, S.; Largis, E.; Li,
11. (a) Lehman, J. M.; Moore, L. B.; Smith-Oliver, T. A.;
Wilkinson, W. O.; Kliewer, S. A. J. Biol. Chem. 1995, 270,
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