ACS Medicinal Chemistry Letters
Letter
a
Scheme 1. Synthesis of Aminopyrazole GPR142 Agonist 22 and 23
a
Reagents and conditions: (a) CH3NHNH2, MeOH, conc. HCl, 60 °C, 71%; (b) Boc-L-phenylalanine, EDCI, py, DMF; (c) 20% TFA/CH2Cl2, 68%
(two steps); (d) glyoxylic acid, NaB(OAc)3H, HOAc, 1,2-dichloroethane/dioxane, 70 °C, 42% for 22; (e) ethyl bromoacetate, N,N-
diisopropylethylamine, 77% for 23.
Notes
The synthesis of the aminopyrazole−phenylalanine GPR142
agonists is exemplified by 22 as shown in Scheme 1. Treating
commercially available 3-oxo-3-(pyridin-4-yl)propanenitrile 24
with methylhydrazine in the presence of concentrated HCl
provided aminopyrazole 25 as the major regioisomeric
product.14 Amide coupling of 25 with boc-L-phenylalanine
following precedent procedures4,5 offered intermediate 26.
Removal of the N-Boc group from 26 provided the amino
intermediate 27, which after reductive amination with glyoxylic
acid provided the final compound 22 in total yield of 20% after
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We thank Dr. Paul Schnier for the high resonance mass
spectroscopy analysis of the compounds discussed in this letter.
REFERENCES
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(1) Fredriksson, R.; Hoglund, P. J.; Gloriam, D. I.; Lagerstrom, M.
C.; Schioth, H. B. Seven evolutionarily conserved human rhodopsin G
protein-coupled receptors lacking close relatives. FEBS Lett. 2003, 554,
381−388.
four steps. Reaction of 27 with ethyl bromoacetate under hunig
̈
base mediated condition offered the prodrug 23 in 77% yield.
Similar synthetic sequences were used to provide the remainder
of the compounds in this letter.
(2) Suesens, U.; Hermans-Borgmeyer, I.; Urny, J.; Schaller, H. C.
Characterisation and differential expression of two very closely related
G-protein-coupled receptors, GPR139 and GPR142, in mouse tissue
and during mouse development. Neuropharmacology 2006, 50, 512−
520.
(3) Xiong, Y.; Motani, A.; Reagan, J.; Gao, X.; Yang, H.; Ma, J.;
Schwandner, R.; Zhang, Y.; Liu, Q.; Miao, L.; Luo, J.; Tian, H.; Chen,
J.-L.; Murakoshi, M.; Nara, F.; Yeh, W.-C.; Cao, Z. Submitted for
publication.
(4) Lizarzaburu, M.; Turcotte, S.; Du, X.; Duqutte, J.; Fu, A.; Houze,
J.; Li, L.; Liu, J.; Oda, K.; Okuyama, R.; Reagan, J. D.; Yu, M.; Medina,
J. C. Discovery and optimization of a novel series of GPR142 agonists
for the treatment of type 2 diabetes mellitus. Bioorg. Med. Chem. Lett.
2012, 22, 5942−5947.
(5) Du, X.; Kim, Y.-J.; Lai, S.; Chen, X.; Lizarzaburu, M.; Turcotte, S.;
Oda, K.; Okuyama, R.; Nara, F.; Murakoshi, M.; Fu, A.; Reagan, J.; Liu,
Q.; Zhang, Y.; Motani, A.; Fan, P.; Xiong, Y.; Shen, W.; Li, L.; Houze,
J.; Medina, J. C. Phenylalanine derivatives as GPR142 agonists for the
treatment of Type II diabetes. Bioorg. Med. Chem. Lett. 2012, 22,
6218−6223.
(6) Inositol Phosphate Accumulation Assay-HEK293 cells were
dispensed into a poly-D-lysine tissue culture treated 96-well plate at a
density of 25 000 cells per well. The next day, the cells (∼80−90%
confluent) were transfected with 100 ng of receptor plasmid per well
using Lipofectamine2000 according the manufacturer’s instructions.
Six hours after transfection the media was replaced with inositol free
DMEM/10% dialyzed FCS supplemented with 1.0 μCi/mL triturated
inositol. After incubation overnight, the cells were washed once in
HBSS and then treated with the 100 μL HBSS/0.01% BSA containing
various concentrations of test compounds (prepared as above in
DMSO) and 10 mM LiCl, and incubated at 37 °C for 1 h. The media
was aspirated, and the cells were lysed with ice cold 20 mM formic
acid. After incubation at 4 °C for 5 h, the lysate were added to yttrium
silicate SPA beads, allowed to settle overnight, and read on a Beckman
In summary, the lead optimization campaign on our
aminopyrazole−phenylalanine GPR142 agonist lead series has
led to the discovery of a pyrazole ring as the optimal center ring
replacement, which provided compounds with good potency
and low serum EC50 shift. The acetic acid substituent on the
phenylalanine nitrogen significantly improved in vitro and in
vivo metabolic stability. Tool compound 22 derived from these
optimizations, together with its ethyl ester prodrug 23,
demonstrated robust in vivo efficacy through their ability to
increase insulin secretion and lowering plasma glucose level.
These effects were not unique to mouse native islets, but were
also demonstrable in an in vivo model of human islet function.
Further studies on higher species are currently in process, and
the results will be published elsewhere when they become
available.
ASSOCIATED CONTENT
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S
* Supporting Information
Synthetic procedures and characterization data for all
compounds. This material is available free of charge via the
AUTHOR INFORMATION
■
Corresponding Author
*(M.Y.) Tel: 650-244-2050. Fax 650-837-9630. E-mail: yum@
Present Address
§Presidio Pharmaceuticals, Inc., 1700 Owens Street, Suite 585,
San Francisco, California 94158, United States.
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dx.doi.org/10.1021/ml4000854 | ACS Med. Chem. Lett. XXXX, XXX, XXX−XXX