Phenylalanine derivatives as GPR142 agonists for the treatment of Type II diabetes

Article abstract of DOI:10.1016/j.bmcl.2012.08.015

GPR142 is a novel GPCR that is predominantly expressed in pancreatic β-cells. GPR142 agonists potentiate glucose-dependent insulin secretion, and therefore can reduce the risk of hypoglycemia. Optimization of our lead pyridinone-phenylalanine series led to a proof-of-concept compound 22, which showed in vivo efficacy in mice with dose-dependent increase in insulin secretion and a decrease in glucose levels.

Full text of DOI:10.1016/j.bmcl.2012.08.015

Bioorganic & Medicinal Chemistry Letters 22 (2012) 6218–6223
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Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Phenylalanine derivatives as GPR142 agonists for the treatment of Type II
diabetes
Xiaohui Du a, , Yong-Jae Kim a, SuJen Lai a, Xi Chen a, Mike Lizarzaburu a, Simon Turcotte a, Zice Fu a,
⇑
Qingxiang Liu a, Ying Zhang a, Alykhan Motani a, Kozo Oda b,c, Ryo Okuyama b,c, Futoshi Nara b,c
,
Michiko Murakoshi b,c, Angela Fu a, Jeff D. Reagan a, Peter Fan a, Yumei Xiong a, Wang Shen a, Leping Li a,
Jonathan Houze a, Julio C. Medina a
a Amgen Inc, 1120 Veterans Blvd., South San Francisco, CA 94080, USA
b Daiichi Sankyo company limited, 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan
c Daiichi Sankyo company limited, 1-16-13 Kitakasai, Edogawa-ku, Tokyo 134-8630, Japan
a r t i c l e i n f o
a b s t r a c t
Article history:
GPR142 is a novel GPCR that is predominantly expressed in pancreatic b-cells. GPR142 agonists potenti-
ate glucose-dependent insulin secretion, and therefore can reduce the risk of hypoglycemia. Optimization
of our lead pyridinone-phenylalanine series led to a proof-of-concept compound 22, which showed
in vivo efficacy in mice with dose-dependent increase in insulin secretion and a decrease in glucose
levels.
Received 7 June 2012
Revised 26 July 2012
Accepted 1 August 2012
Available online 10 August 2012
Ó 2012 Elsevier Ltd. All rights reserved.
Keywords:
GPR142 agonist
Type II diabetes
Glucose-lowering
Insulin secretagogue
Type 2 diabetes mellitus (T2DM) is characterized by hypergly-
cemia as a result of insulin resistance combined with reduced insu-
lin secretion from pancreatic b-cells. Uncontrolled hyperglycemia
is a major risk factor for microvascular and macrovascular compli-
cations including retinopathy, nephropathy, neuropathy, and
accelerated cardiovascular disease.1 Insulin secretagogues such as
sulfonylureas and meglitinides are widely used for the treatment
of type 2 diabetes. However, their action is independent of extra-
cellular blood glucose concentration and therefore can cause hypo-
glycemia.2 This liability triggered considerable interest from the
pharmaceutical industry to pursue glucose-stimulated insulin
secretagogues to treat T2DM, such as DPP-IV inhibitors, analogs
of glucagon-like peptide-1,3 and GPR40 agonists.4
GPR142 is a novel G protein-coupled receptor (GPCR) which is
predominantly expressed in pancreatic b-cells. It was found to be
a receptor for aromatic amino acids with tryptophan representing
one of the most potent ligands (EC50 of 0.2–1 mM).5 It was also
demonstrated that GPR142 agonists potentiate glucose-dependent
insulin secretion from isolated pancreatic islets and in rodent mod-
els. Thus, a potent and selective GPR142 agonist could prove to be
an effective anti-diabetic therapeutic with reduced risk of
hypoglycemia.
We have previously reported our efforts in identifying a novel
series of GPR142 agonists with a pyridinone-phenylalanine scaf-
fold.6 Previous lead optimization efforts discovered that addition
of a methyl thiazole moiety (D-ring, Scheme 1) to the amino group
of the phenylalanine motif in compound 1 boosted the potency of
the agonists more than 50-fold. Compound 2 displayed an EC50 of
93 nM and a 120% Emax compared to tryptophan in our human ino-
sitol phosphate (IP) accumulation assay.7 However, due to the lack
of metabolic stability owing to N-dealkylation, compound 2 dis-
played high clearance (3.4 L/(hꢀkg)) after an i.v. administration of
0.5 mg/kg, and poor oral exposure (11
with a 2 mg/kg oral dose) in rats. Therefore, it was not suitable
l
gꢀh/L, 2% bioavailability
as a tool compound for in vivo investigation.
Herein, we describe our identification of a tool compound 22
which demonstrated in vivo efficacy for this series of agonists.
The syntheses of the agonists are shown in Schemes 2–4. The
syntheses of compounds 2–6, 14, 16, 17, 19, 20 followed the syn-
thetic route in our earlier work6, applying reductive aminations
with different heterocyclic aldehydes or ketones for the introduc-
tion of the D-ring. Compounds 7, 18, 21–24 and 27 were prepared
through a synthetic route shown in Scheme 2. 8 Suzuki coupling of
4-pyridine boronic acid with 5-bromo-2-methoxypyridin-3-amine
generated 6-methoxy-[3,40-bipyridin]-5-amine 8. (R)-2-acetoxy-3-
⇑
Corresponding author.
E-mail address: xdu@amgen.com (X. Du).
0960-894X/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.bmcl.2012.08.015

X. Du et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6218–6223
6219
H
N
B
and six-membered heterocyclic D-rings were tolerated with good
potency and efficacy, such as imidazole, pyrazole, pyridine and
pyrimidine. However, all of them displayed high turnover in rat
O
H
N
B
O
O
S
O
NH2
H
N
D
N
H
9
A
N
N
H
and human microsomal stability assays.
N
A
N
C
The benzyl-like nature of the carbon between the amino group
and the heterocyclic D-ring may be one explanation as to why N-
dealkylation was so facile. To mitigate this effect, the linker was
elongated to two carbons (compound 13 in Table 2). The potency
and efficacy were both significantly lowered, while no improve-
ment in microsomal stability was seen. The heteroaromatic D-ring
was also replaced with saturated heterocycles as in compounds
14–17. Although the microsomal stabilities of compound 14 and
17 were improved, possibly due to the presence of polar groups
such as a sulfone or amide, none of the compounds was sufficiently
potent.
C
1
2
h-GPR142 EC50 (Emax
4.8 µM (113%)
)
h-GPR142 EC50 (Emax
93 nM (120%)
)
Scheme 1. Increased potency through N-substitution.
phenylpropanoic acid 9 was converted to the acid fluoride with
cyanuric fluoride and coupled with compound 8 to form an amide
bond. Subsequent deprotection of the acetate group generated (R)-
2-hydroxy-N-(6-methoxy-[3,40-bipyridin]-5-yl)-3-phenylpropana-
mide 10. Compound 10 was converted to its nosylate upon
treatment with 4-nitrobenzene-1-sulfonyl chloride (nosyl chlo-
ride). Nucleophilic displacement of the nosylate with various
amines followed by deprotection under acidic conditions gener-
ated the final GPR142 agonists.
Compounds 25 and 26 were made through alkylation of the B-
ring pyridinone nitrogen of compound 22 with either tert-butyl 2-
bromoacetate or 2-chloro-N,N-dimethylethanamine (Scheme 3).
Synthesis of compound 35 followed the synthetic route shown
in Scheme 4. 2-Chloroisonicotinic acid 28 was refluxed in thionyl
chloride to generate the acid chloride and then coupled with
hydrazinecarbothioamide to form 2-(2-chloroisonicotinoyl)hydra-
zinecarbothioamide 29. Acidic cyclization of compound 29 using
PPA generated thiadiazole 30. The chloro group in compound 30
was then converted to a methyl amino group using a SNAr reaction.
The amino group connected to thiadiazole in compound 31 was
coupled to Boc-protected phenylalanine to generate compound
32. The Boc group in the resulting compound 32 was removed with
TFA. Reductive amination of compound 33 with thiazole-4-carbal-
dehyde led to compound 35. The other compounds in Table 5, i.e.,
34, 36, and 37, were prepared by the same route starting from the
appropriate heterocyclic carboxylic acid.
We then turned our attention to adding a substituent to the
benzyl-like carbon to prevent the N-dealkylation. Methyl substitu-
tion in compound 18 (Table 3) was well tolerated with good effi-
cacy and only
a two-fold decrease in potency. For mono-
substitution, the stereochemistry significantly influenced potency
with one diastereomer being more potent as evident in the diaste-
reomeric pair of compounds 18 and 19. Compounds with ethyl
substitution (20), and dimethyl substitution (21) 10 displayed a fur-
ther decline in potency and significant lowering in efficacy, indicat-
ing that there is a steric limitation in this position. The exception
was the cyclopropyl substitution on the benzylic position. Com-
pound 22 not only was more potent than the parent pyridylmethyl
compound 6, but also displayed significantly improved stability
(<10% turnover in human microsomes and 60% turnover in rat
microsomes) as well as a great efficacy (127%). Replacing the pyr-
idine D-ring in compound 22 by pyrimidine (23) or methyl thiazole
(24) also resulted in a combination of good potency, efficacy and
improved microsomal stability compared to compound 6. How-
ever, compound 22 displayed the best overall profile. The dramatic
difference between cyclopropyl- and dimethyl- substitution pat-
tern could be due to the more planar nature of the cyclopropyl ring
and reduced steric demand through distinct bond angles. As a re-
sult, the cyclopropyl ring can orient itself much differently from
the dimethyl group.
Our initial lead optimization efforts aimed at exploring different
heterocyclic D-rings to see whether the microsomal stabilities of
the agonists could be improved while maintaining the potency
and efficacy. The results are listed in Table 1. A variety of five-
The pharmacokinetic profile of compound 22 was evaluated in
rats (Table 6). Though compound 22 showed improved microsomal
stability, it nonetheless displayed high in vivo clearance. The
O
O
NH2
B(OH)2
N
NH2
N
a
+
NO2
N
Br
N
8
O
S
O
O
OH
OAc
H
O
N
H
N
O
N
HO
N
b
c
N
d
O
O
O
9
10
N
e
11
R
R
HN
O
O
N
HN
H
H
N
N
N
HN
O
O
7, 17, 18, 21-24, 27
N
12
Scheme 2. Synthesis of GPR142 agonists. a. Pd2(dba)3, X-Phos, K3PO4, BuOH, 3 h, 110 °C, 74%; b. (i) cyanuric fluoride, pyridine, DCM, ꢁ20 °C–10 °C; then 8, DIPEA, DCM; (ii)
K2CO3, 88% for 2 steps; c. 4-nitrobenzene-1-sulfonyl chloride, Et3N, 69%; d. 1-(pyridin-2-yl)cyclopropanamine or other primary amines RNH2, DMF, 100 °C, 30–59%; e.
dioxane, water, HCl, 50 °C, 41–90%.

6220
X. Du et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6218–6223
O
N
HO
O
O
N
O
O
O
HN
O
N
O
N
O
N
a
NH
b
NH
N
H
NH
N
H
N
H
N
N
N
22
25
c
N
O
N
O
N
NH
N
H
N
26
Scheme 3. Synthesis of GPR142 agonists 25 and 26. a. tert-butyl 2-bromoacetate, Cs2CO3, DMF, 70 °C, 43%; b. TFA, 100%; c. 2-chloro-N,N-dimethylethanamine, Cs2CO3, DMF,
70 °C, 34%.
O
O
N
Table 1
N
H
N
NH2
Evaluation of various D-ring heterocycles
NH2
OH
N
H
S
a
b
c
N
N
N
H
N
S
N
O
O
Cl
Cl
28
29
30
Cl
NHBoc
NHR
N
H
N
S
N
O
N
N
NH2
d
N
H
e
S
N
N
Compound
R
h-GPR142 IP
EC50
Microsome %Turnoverc
h/r
HN
31
32
HN
Emaxa,b(%)
S
N
(l
M)a
O
NH2
N
S
N
O
HN
N
N
S
N
H
f
2
3
4
0.93
2.2
120
93
68/99
78/95
60/96
N
N
N
H
S
N
N
33
HN
35
O
HN
NH
0.11
107
N
N
Scheme 4. Synthesis of GPR142 agonist 35. a. (i) SOCl2, reflux; (ii) hydra-
zinecarbothioamide, pyridine, 55%; b. PPA, 100 °C, 93%; c. MeNH2 H2O, 130 °C,
46%; d. Boc-phenylalanine, HBTU, 99%; e) TFA, 52%; f. NaBH(OAc)3, 50 °C, 1 h,
thiazole-4-carbaldehyde, 43%.
5
0.21
92
90/100
N
6
7
0.095
0.44
155
95
95/95
90/99
N
N
N
unusually high clearance could be due to a combination of first and
second phase metabolism potentially including glucuronidation of
the pyridinone. Modifications on the pyridinone B-ring moiety of
compound 22 were made to prevent the potential glucuronidation
from occurring (Table 4). While substitution on the pyridinone
nitrogen with either a basic or an acidic group (compounds 25
and 26) still resulted in high clearance in rats, compound 27 with
a methoxy-pyridine B-ring had a much improved clearance of
1.25 L/(hꢀkg) in rat as well as good potency and efficacy. However,
the potency of compound 27 was significantly shifted in the pres-
ence of serum (20-fold in 100% serum) which rendered it unsuit-
able for in vivo validation. Nevertheless, these changes
demonstrated that B-ring modifications could influence the phar-
macokinetic properties of the agonists significantly. We decided
to next try additional heterocyclic B-rings to optimize the pharma-
cokinetic properties and serum shift.
At this point, it was also discovered that the cyclopropyl moiety
in these compounds caused CYP 3A4 time-dependent inhibition. As
this was considered undesirable even for a tool compound, we re-
moved the cyclopropyl substitution at the D-ring while exploring
further modifications on the B-ring. Previous studies6 demon-
strated that the B-ring tolerated polar heterocycles such as pyrim-
idine. The thiadiazole B-ring was among the first B-rings we
explored in our optimization efforts and it combined a number of
a
Human inositol phosphate accumulation assay with HEK293 cells. See Ref. 7 for
assay protocol.
Percentage of maximal tryptophan response at 10
% Turnover of parent compound after 30 min. of incubation with human or rat
microsomes. See Ref. 9 for detailed conditions.
b
l
M.
c
favorable attributes. Table 5 shows a number of agonists with thia-
diazole as B-ring. It was encouraging that compound 34 showed
equal potency and efficacy as compound 2, with very good micro-
somal stability and low serum shift of only two-fold. Furthermore,
consistent with the low microsomal turnover, compound 34 had
low clearance of 0.44 L/(hꢀkg) in rat (Table 5). Even though its oral
bioavailability was only 10%, it provided a good starting point. Sub-
sequent work resulted in compounds 35–37 shown in Table 5.
While compounds 36 and 37 exhibited higher in vivo clearance
than compound 34, the methylamino-substituted compound 35
showed improved in vivo clearance and bioavailability compared
to compound 34 (Table 6). With a moderate microsomal stability,
the lower in vivo clearance of 35 might be associated with higher
protein-binding as evidenced in a higher six-fold serum shift of this
compound. Though blessed with good efficacy at the human

X. Du et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6218–6223
6221
Table 2
D-ring modifications to improve microsomal stability
H
N
O
O
NHR
N
H
N
Compd
R
h-GPR142 IP
EC50
M)a
Microsome%Turnoverc h/r
(l
Emaxa,b(%)
120
S
2
0.093
1.32
68/99
N
13
76
91
100/100
N
O
14
20
21/58
S
O
15
16
0.39
1.06
78
84
83/98
66/80
O
O
HN
17
2.23
78
19/67
O
a
b
c
Human inositol phosphate accumulation assay with HEK293 cells. See Ref. 7 for assay protocol.
Percentage of maximal tryptophan response at 10 M.
% Turnover of parent compound after 30 min. of incubation with human or rat microsomes. See Ref. 9 for detailed conditions.
l
Table 3
D-ring
a-benzylic substitutions to improve microsomal stability of the agonists
H
N
O
O
NHR
N
H
N
Compd
R
h-GPR142 IP
EC50
M)a
Microsome % Turnoverc h/r
(l
Emaxa,b(%)
155
6
0.095
0.22
95/95
N
N
N
18
107
60
100/99
19
6.0
95/95
85/95
20d
0.73
81
N
N
N
N
N
21
22
23
9.45
57
127
114
>95/100
<10/60
21/67
0.054
0.099
N
S
24
0.20
106
64/74
a
b
c
Human inositol phosphate accumulation assay with HEK293 cells. See Ref. 7 for assay protocol.
Percentage of maximal tryptophan response at 10 M.
% Turnover of parent compound after 30 min. of incubation with human or rat microsomes. See Ref. 9 for detailed conditions.
l
d
Racemic.

6222
X. Du et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6218–6223
Table 4
Modifications on B-ring
N
O
B
NH
N
H
N
Compd
R
h-GPR142 IP
Micorsome % Turnoverc h/r
CLd
5.0
EC50
(l
M)a
Emaxa,b(%)
HOOC
N
O
25
26
0.26
83
10/12
N
N
O
0.28
0.35
118
123
19/22
15/54
3.1
1.3
N
O
27
a
Human inositol phosphate accumulation assay with HEK293 cells. See Ref. 7 for assay protocol.
Percentage of maximal tryptophan response at 10 lM.
% Turnover of parent compound after 30 min. of incubation with human or rat microsomes. See Ref. 9 for detailed conditions.
CL in L/(hꢀkg).
b
c
d
Table 5
Table 6
Agonists with thiadiazole as B-ring and various A rings
Detailed pharmacokinetic parameters of selected compounds
S
N
N
O
Compound #
22
34
35
H
N
A
iva
CL(L/(hꢀkg))
5.0
177
1.1
0.44
1235
0.21
0.23
S
N
N
H
AUC
Vdss (L/kg)
l
gꢀh/L)
3030
0.23
T1/2 (h)
Dose (mg/kg)
0.2
0.89
1.2
0.5
1.2
0.67
Compd
R
h-GPR142 IP
EC50
Emaxa,b(%)
M)a
Microsome%Turnoverc
h/r
CL/%Fd
(L/
(hꢀkg))
poa
AUC
MRT (h)
F (%)
l
gꢀh/L)
77
1.79
20
2.0
480
1.93
10
2.0
1730
2.36
36
2.0
(
l
Dose (mg)
34
35
0.086
0.036
115
14/10
58/66
0.44/10
0.23/36
a
PK done in rat. For iv in rat, 0.5 mg/kg for all compounds except 0.67 mg/kg for
N
N
compound 35, n = 2; for po in rat, 2 mg/kg for all compounds, n = 3.
96
HN
N
both human and mouse GPR142 IP assay (mGPR142 EC50 = 1.8 nM,
36
37
0.18
0.39
86
74
19/35
29/57
1.7/19
2.4/32
Emax = 81%).
N
B6D2F1 (Harlan) male mice were dosed subcutaneously with
N
increasing doses of compound 22 or vehicle (milliQ water) at
10 mL/kg. 15 min later, mice were challenged with an oral glucose
bolus (2 g/kg). 7.5 min after glucose challenge, blood samples were
collected and assayed for blood glucose (AccuChek glucometer),
serum insulin (ELISA, Alpco) and serum levels of compound 22.
The 7.5 min time point was based on the previously determined
time to reach peak insulin levels in response to oral glucose chal-
lenge (Tmax). The Tmax was unaffected by treatment with com-
pound 22.
S
a
Human inositol phosphate accumulation assay with HEK293 cells. See Ref. 7 for
assay protocol.
Percentage of maximal tryptophan response at 10
% Turnover of parent compound after 30 min. of incubation with human or rat
microsomes. See Ref. 9 for detailed conditions.
b
lM.
c
d
PK done in rat. For iv in rat, 0.5 mg/kg for all compounds except 0.67 mg/kg for
compound 35, n = 2; for po in rat, 2 mg/kg for all compounds, n = 3.
Dose-related increase in serum insulin levels (plasma
EC50 = 0.29
l
M; GraphPad Prism; non-linear fit, variable Hill slope)
M) were ob-
GPR142, a further study of compound 35 indicated that it was a
partial agonist (15 nM IC50, 37% Emax) in HEK293 cells transfected
with mouse GPR142. In addition, compound 35 was chemically
not stable under weakly acidic condition. Both issues prevented
this compound from being further used as a tool compound to
demonstrate in vivo efficacy. Nevertheless, the modifications on
the B-ring again indicated that this was a good site for improving
and decrease in blood glucose levels (EC50 = 0.85
l
served in mice (Fig. 1). These results correlated very well with
the observed dose-dependent increase in serum levels of com-
pound 22.
In conclusion, continued optimization of the phenylalanine ser-
ies demonstrated that the D-ring tolerated a variety of heterocy-
cles, and that B-ring variation could have significant impact on
the pharmacokinetic properties of the agonists. The optimization
also led to compound 22, which showed in vivo efficacy in mouse
the pharmacokinetic properties11
.
Compound 22 was therefore selected for in vivo evaluation in a
glucose-challenged model in mice. Compound 22 was potent in

X. Du et al. / Bioorg. Med. Chem. Lett. 22 (2012) 6218–6223
6223
400
350
300
250
with dose-dependent increase in insulin secretion and decrease in
glucose level. Further optimization on this series is ongoing and
will be reported in due course.11
+6%
0%
-3%
-4%
-13%
-15%*
References and notes
1. a) Nazimek-Siewniak, B.; Moczulski, D.; Grzeszczak, W. J. Diabetes
Complications 2002, 16, 271; b) Kles, K. A.; Vinik, A. I. Curr. Diabetes Rev.
2006, 2, 131; c) Rahman, S.; Rahman, T.; Ismail, A. A.; Rashid, A. R. Diabetes
Obes. Metab. 2007, 9, 767.
2. Burge, M. R.; Sood, V.; Sobhy, T. A.; Rassam, A. G.; Schade, D. S. Diabetes Obes.
Metab. 1999, 1, 199.
3. Drucker, D. J.; Nauck, M. A. Lancet 2006, 368, 1696.
4. For a review, see Bharate, S. B.; Nemmani, K. VS; Vishwakarma, R. A Expert Opin.
Ther. Pat. 2009, 19, 237.
0
00
10
30
00
00
00
5.
.0
0.
0.
0.
1.
3.
30
Dose of Cmpd 22
(mg/kg, sc)
5. 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. manuscript is in preparation.
6. Lizarzabura, M.; Turcotte, S.; Du, X.; Duquette, J.; Fu, A.; Houze, J.; Li, L.; Liu, J.;
Oda, K.; Okuyama, R.; Yu, M.; Reagan, J.; Medina, J. C. in press,corrected proof,
Bioorg. Med. Chem. Lett..
7. 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 (ꢂ80–90% confluent) were transfected with 100 ng
receptor plasmid per well using Lipofectamine2000 according the
manufacturer’s instructions. 6 h after transfection the media was replaced
+98%*
+81%*
40
30
20
10
0
+58%
+41%
+15%
-9%
with inositol free DMEM/10% dialyzed FCS supplemented with 1
tritiated inositol. After incubation overnight, the cells were washed once in
HBSS and then treated with the 100 L HBSS/0.01% BSA containing various
lCi/mL
00
3.
00
30.
0.00
0.10
0.30
1.00
5.00
l
Dose of Cmpd 22
(mg/kg, sc)
concentrations of test compounds (prepared as above in DMSO), 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 TopCount scintillation counter. In measuring the EC50 with
serum, HBSS/0.01% BSA was replaced with100% human serum.
100
10
1
8. Compound 13 was prepared through a similar route as depicted in Scheme 2
with nosylate chemistry but relying on a slightly different sequence of steps.
Compound 15 was also synthesized by
a similar route with (R)-
(tetrahydrofuran-2-yl)methanamine as nucleophile and triflate as leaving
group (pyridinone as the B-ring) in 23% yield.
9. Microsome stability was measured in a high throughput format by incubating
inhibitors at 1 lM concentration with rat(r) or human (h) microsomes and the
0.1
0.01
0.1
1
10
100
percentage of the parent compounds remaining were measured after 30 min. of
incubation by liquid chromatography/mass spectrometry analysis. The% of
parent compounds which was metabolized is reported as%turnover.
Dose of Cmpd 22
(mg/kg, sc)
10. Compound 21 had an additional methyl group alpha to the A ring pyridine
nitrogen for the purpose of improving CYP inhibition. The potency difference
was usually within 2 fold between pyridine A ring and methyl pyridine A ring.
11. For further work in this series including more work in B-ring modifications, see
Yu, M. et al. manuscript in preparation to ACS Med. Chem. Lett.
Fig. 1. The in vivo results of dosing compound 22 in a mice glucose-challenge
model. Mice were dosed with compound 22 15 min prior to oral glucose challenge.
Blood samples were collected and assayed for blood glucose, serum insulin and
exposure 7.5 min after oral glucose challenge. Data are shown as mean + sem, n = 7
mice per dose group. (a) Compound 22 lowered glucose in a dose-dependent
manner. (b) Compound 22 stimulated the secretion of insulin in a dose-dependent
manner. (c) Plasma exposure of compound 22 at different doses.