Design, synthesis, and pharmacological evaluation of 2-(4-sulfonylphenyl)-2-[(E)-pyrrolidin-1-ylimino]-N-thiazoleacetamides as glucokinase activators

Article abstract of DOI:10.1016/j.bmcl.2020.127249

This paper presents the synthesis and glucokinase activity of novel hydrazone derivatives. The 2-(4-cyclopropylsulfonylphenyl)-2-[(E)-pyrrolidin-1-ylimino]-acetamide derivatives 5a–5h presented the in vitro glucokinase activities and in vivo blood glucose-lowering effects in mice. Particularly, 5h showed an oral hypoglycemic effect in rats at 1 mg/kg. These hydrazone derivatives are a potential new class of glucokinase activators for the treatment of type 2 diabetes.

Full text of DOI:10.1016/j.bmcl.2020.127249

Journal Pre-proofs
Design, synthesis, and pharmacological evaluation of 2-(4-sulfonylphenyl)-2-
[(E)-pyrrolidin-1-ylimino]-N-thiazoleacetamides as glucokinase activators
Hiroshi Sugama, Tetsuji Matsudaira, Hideyuki Yanagisawa, Rikiya Ohashi,
Masao Nawano, Kosuke Yasuda, Hiromitsu Takayama
PII:
S0960-894X(20)30354-1
DOI:
Reference:
https://doi.org/10.1016/j.bmcl.2020.127249
BMCL 127249
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Bioorganic & Medicinal Chemistry Letters
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Revised Date:
Accepted Date:
31 January 2020
24 April 2020
4 May 2020
Please cite this article as: Sugama, H., Matsudaira, T., Yanagisawa, H., Ohashi, R., Nawano, M., Yasuda, K.,
Takayama, H., Design, synthesis, and pharmacological evaluation of 2-(4-sulfonylphenyl)-2-[(E)-pyrrolidin-1-
ylimino]-N-thiazoleacetamides as glucokinase activators, Bioorganic & Medicinal Chemistry Letters (2020), doi:
https://doi.org/10.1016/j.bmcl.2020.127249
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Design, synthesis, and pharmacological
evaluation of 2-(4-sulfonylphenyl)-2-[(E)-
pyrrolidin-1-ylimino]-N-thiazoleacetamides as
glucokinase activators
Hiroshi Sugama a,b,*, Tetsuji Matsudaira a, Hideyuki Yanagisawa a, Rikiya Ohashi a,
Masao Nawano a, Kosuke Yasuda a, Hiromitsu Takayama b
aSohyaku, Innovative Research Division, Mitsubishi Tanabe Pharma Corporation,
1000, Kamoshida-cho, Aoba-ku, Yokohama 227-0033, Japan
bGraduate School of Pharmaceutical Sciences, Chiba University, 1-8-1, Inohana, Chuo-
ku, Chiba 260-8675, Japan
Keywords:
Glucokinase activators
Type 2 diabetes
Hydrazone derivatives
hERG inhibition
Corresponding author. Tel.: +81 45 963 7196; Fax: +81 45 963 7207.
E-mail address: sugama.hiroshi@mm.mt-pharma.co.jp (H. Sugama)
1

ABSTRACT
This paper presents the synthesis and glucokinase activity of novel hydrazone
derivatives. The 2-(4-cyclopropylsulfonylphenyl)-2-[(E)-pyrrolidin-1-ylimino]-
acetamide derivatives 5a-5h presented the in vitro glucokinase activities and in vivo
blood glucose-lowering effects in mice. Particularly, 5h showed an oral hypoglycemic
effect in rats at 1 mg/kg. These hydrazone derivatives are a potential new class of
glucokinase activators for the treatment of type 2 diabetes.
2

Type 2 diabetes mellitus is a progressive and multifactorial disease, and it is difficult to
maintain appropriate glycemic controls even with several glucose-lowering agents.1 Thus,
there is a need for new agents with a complementary mechanism of action. Glucokinase
(GK) is one of the four enzymes in the hexokinase family in mammalian, which catalyzes
the conversion of glucose to glucose-6-phosphate (G6P) at the initial step of glucose
metabolism.2 Its major expression organs are the liver hepatocyte and the pancreatic beta-
cell. In the high blood glucose level, GK contributes to glucose consumption in the liver
and increasing G6P in the pancreas beta-cell enhances glucose stimulating insulin
secretion. Thus, GK activators are considered to be a promising drug target for type 2
diabetes with both hepatic and pancreatic effects.3
Representative GK activators and our designed compounds are depicted in Figure 1. In
early study, Hoffman La Roche group pioneered the field of allosteric GK activators by
developing phenylacetamide derivatives 1 and 2,4 followed by compound 3 (PSN-GK1)
from OSI-Prosidion.5 Compound 1 was reported as an orally active GK activator but
withdrawn from the development in human because of its potential cardiovascular risk
represented with a human ether-a-go-go related gene (hERG) channel inhibition.6 Based
on that knowledge, we designed a novel hydrazone derivative 4a, in which the central
carbon-carbon double bond in 2 was replaced with carbon-nitrogen double bond, to avoid
3

hERG channel inhibition by reducing lipophilicity.7 Here we describe the synthesis, in
vitro GK activity, and in vivo hypoglycemic effects of novel hydrazone derivatives 4a
and 5a-5h.
The synthetic route is outlined in Scheme 1. The 2-oxo-2phenylacetates 6 and 9 were
set as the key intermediates and prepared by known procedures.8 For the synthesis of 4a,
the ester 68a was hydrolyzed with aqueous hydrochloric acid to obtain the acid 7, which
was converted to the hydrazone 8 through condensation reaction with 1-aminopyrrolidine
hydrochloride. Then, 8 and 2-aminothiazole were coupled by employing 1-(3-
dimethylaminopropyl)-3-ethylcarbodiimide (EDC) and catalytic amounts of 4-
dimethylaminopyridine (DMAP) to give 4a. The geometric stereochemistry in 4a was
determined as the E-isomer by 1H NMR nuclear overhauser effect (NOE) analysis.9 For
the synthesis of 5a-5h having a cyclopropylsulfonyl group in the molecule, a common
intermediate 11 was prepared as follows. The known ester 98b was treated with 1-
aminopyrrolidine hydrochloride and triethylamine to give the hydrazone ester as an E/Z
mixture, which could be separated by SiO2 column chromatography. The polar isomer 10
was hydrolyzed with aqueous sodium hydroxide to give carboxylic acid 11. The
1
geometric stereochemistry of 11 was determined as the E-isomer using H NMR NOE
analysis.9 The acid 11 was then converted to the corresponding amides 5a-5f and 12 by
4

condensation with various heteroarylamines. During the conversion process, the
isomerization of E/Z stereochemistry at the hydrazone moiety was not observed. Further,
reductive amination of 5-formylthiazol-2-ylamide 12 with the corresponding 1-
substituted piperazine derivatives gave 5g and 5h.10
The effects of these hydrazone derivatives on human GK activity and blood glucose
reduction were evaluated in fasted C57BL/6J mice. The structure−activity relationships
are shown in Table 1. First, we confirmed that the hydrazone derivative had sufficient
efficacy as GK activator because methylsulfonylphenyl derivative 4a showed GK
activation at the micromolar level. To improve in vitro potency, we adopted
cyclopropylsulfonylphenyl substituent, which was searched by Bertram et al., in the
development of compound 3.5 As a result, the cyclopropylsulfonyl-substituted hydrazone
derivative 5a had a 10-fold higher in vitro potency than 4a. Furthermore, 5a exhibited an
oral glucose-lowering effect in mice at 10 mg/kg. By introducing 5-chloro substituent
onto thiazole ring, 5b showed 10-fold more potent GK activation than 5a. However, 5b
indicated low water solubility in pH 6.5 buffer. Further, 5a and 5b also displayed hERG
inhibitory activity which could be associated with cardiotoxicity caused by QT interval
prolongation.10 Thus, we focused on increasing solubility and avoiding hERG channel
inhibition while maintaining sufficient GK activation. As a result, other heteroarylamide
5

derivatives 5c-5f were investigated. Pyridin-2-ylamide derivative 5c showed lower in
vitro GK activation and in vivo efficacy than thiazol-2-ylamide derivative 5a. 1,3,5-
Thiadiazole-2-ylamide derivative 5d had moderate in vitro GK activation. On the other
hand, 5-methyl substituted thiazole-2-ylamide 5e and 1,3,4-thiadiazole-2-ylamide 5f
showed good in vitro GK activation and in vivo efficacy. Unlike the 5-chloro-thiazole-2-
ylamide derivative 5b, the 5-methylthiazole-2-ylamide derivative 5e was found incapable
of performing hERG channel inhibitory activity. To increase the water solubility, amino
substituents were introduced onto the methyl group in 5e. 4-Methylpiperazin-1-ylmethyl
derivative 5g exhibited good water solubility and in vitro GK activation but showed
hERG inhibitory activity. We supposed that the terminal basic amine in 5g interacted with
hERG channel. In contrast, 5h having a 4-acetylpiperazin-1-ylmethyl substituent showed
moderate GK activity without hERG channel inhibition. Therefore, we conclude that 5h
is a well-balanced compound with in vivo GK efficacy in mice and good water solubility.
Based on the results described above, 5h was advanced to evaluate single oral
administration in overnight-fasted Sprague-Dawley rats. As a result, this compound
reduced blood glucose levels at 1, 3, 10 and 30 mg/kg in a dose-dependent manner
compared to the vehicle control group. Furthermore, the 10 and 30 mg/kg groups showed
6

sustained hypoglycemic effects with statistically significant differences from the vehicle
group even 7 hours after administration (Figure 2).
In summary, we can conclude that among the synthetic hydrazone derivatives,
cyclopropylsulfonylphenyl substituted hydrazone 5a-5h showed in vitro GK activation
and hypoglycemic effects in mice. Particularly, 5h was compatible with good water
solubility and hERG inhibition avoidance. The 5h presented a dose-dependent oral
hypoglycemic effect in rats. These hydrazone derivatives have potential as a new
chemical class of glucokinase activators for type 2 diabetes treatment.
Acknowledgements
We thank Dr. Kazutoshi Sugawara, Dr. Sumihiro Nomura and Dr. Shigeki Sakamaki for
helpful discussion.
7

References and notes
1. (a) Turner, R. C.; Cull, C. A.; Frighi, V.; Holman, R. R. J. Am. Med. Assoc.
1999, 281, 2005-2012. (b) Krentz, A. J.; Bailey, C. J. Drugs 2005, 65, 385-411.
2. Matschinsky, F. M.; Magnuson, M. A., eds., In Glucokinase and Glycemic
Disease: From Basics to Novel Therapeutics, Karger, Basel, 2004.
3. For review, see: Matschinsky, F. M.; Assessing the potential of glucokinase
activators in diabetes therapy. Nature Review Drug Discovery 2009, 8, 399-416.
4. (a) Grimsby, J.; Sarabu, R.; Corbett, W. L.; Haynes, N. E.; Bizzarro, F. T.;
Coffey, J. W.; Guertin, K. R.; Hilliard, D. W.; Kester, R. F.; Mahaney, P. E.,
Marcus, L.; Qi, L.; Spence, C. L.; Tengi, J.; Magnuson, M. A.; Chu, C. A.;
Dvorozniak, M. T.; Matschinsky, F. M.; Grippo, J. F. Science 2003, 301, 370-
373. (b) Haynes, N. E.; Corbett, W. L.; Bizzarro, F. T.; Guertin, K. R.; Hilliard,
D. W.; Holland, G. W.; Kester, R. F.; Mahaney, P. E.; Qi, L.; Spence, C. L.;
Tengi, J.; Dvorozniak, M. T.; Railkar, A; Matschinsky, F. M.; Grippo, J. F.;
Grimsby, J.; Sarabu, R. J. Med. Chem. 2010, 53, 3618-3625. (c) Sidduri, A.;
Grimsby, J. S.; Corbett, W. L.; Sarabu, R.; Grippo, J. F.; Lou, J.; Kester, R. F.;
Dvorozniak, M.; Marcus, L.; Spence, C.; Racha, J. K.; Moore, D. J. Bioorg.
Med. Chem. Lett. 2010, 20, 5673-5676.
5. (a) Bertram, L. S.; Black, D.; Briner, P. H.; Chatfield, R.; Cooke, A.; Fyfe, M.
C. T.; Murray, P. J.; Naud, F.; Nawano, M.; Procter, M. J.; Rakipovski, G.;
Rasamison, C. M.; Reynet, C.; Schofield, K. L.; Shah, V. K.; Spindler, F.;
Taylor, A.; Turton, R.; Williams, G. M.; Wong-Kai-In, P.; Yasuda, K. J. Med.
Chem. 2008, 51, 4340-4345. (b) Fyfe, M. C. T.; White, J. R.; Taylor, A.;
Chatfield, R.; Wargent, E.; Printz, R. L.; Sulpice, T.; McCormack, J. G.; Procter,
M. J.; Reynet, C.; Widdowson, P. S.; Wong-Kai-In, P. Diabetologia, 2007, 50,
1277-1287.
6. ClogP values are 2.69 for 1, 2.98 for 2, and 1.61 for 4a.
7. Pal, M. Drug Discovery Today, 2009, 14, 784-792.
8. (a) Creary, X.; Mehrsheikh-Mohammadi, M. E. J. Org. Chem. 1986, 51, 2664-
2668. (b) Magnus, N. A.; Braden, T. M.; Buser, J. Y.; DeBaillie, A. C.; Heath,
P. C.; Ley, C. P.; Remacle, J. R.; Varie, D. L.; Wilson, T. M. Org. Process Res.
Dev. 2012, 16, 830-835.
9. In the 1H-NMR studies of 4a and 11, NOEs were observed as shown below.
8

H
H
H
H
N
N
N
NOE
H
N
NOE
H3C
H
H
OH
N
N
O
O
S
S
O O
S
O O
4a
11
10. Fermini, B.; Fossa, A. A. Nat. Rev. Drug Discovery 2003, 2, 439-447.
9

Supplementary Material
Detailed synthetic procedure for 4a and 5a-5h; description of in vitro GK assay. This
material is available free of charge via the internet.
Declaration of interests
☒
The authors declare that they have no known competing financial interests or
personal relationships that could have appeared to influence the work reported in this
paper.
☐The authors declare the following financial interests/personal
relationships which may be considered as potential competing interests:
10

O
H
N
H
H
N
N
N
N
N
O
S
Me
O
S
Me
O
S
S
S
S
F
O
O
O
O
O
O
3
2
OSI-Prosidion (PSN-GK1)
Roche
1
Roche (RO-28-1675)
N
N
N
N
H
H
N
N
N
N
Het
Me
O
S
O
S
S
O
O
O
O
5a-h
4a
Figure 1. Structures of glucokinase activators and our design for novel hydrazone derivatives.
N
N
O
O
N
N
H
(a)
(c)
(b)
(ref. 8a)
O
OH
OH
N
N
Me
O
Me
O
Me
O
Me
O
S
Me
S
S
S
S
S
O
O
O
O
O
O
O
O
6
7
8
4a
N
N
N
O
N
N
N
(f) or (g)
H
(e)
(d)
O
O
OH
N
N
(ref. 8b)
Het
O
O
O
O
S
S
S
S
S
O
O
O
O
O
O
O
O
9
10
11
5a-f, 12
*
N
*
*
*
N
*
*
*
*
*
*
(h)
N
N
N
N
N
N
N
N
=
N
,
,
,
,
,
,
,
Het
S
S
S
S
S
S
S
S
N
CH3
Cl
CH3
CH3
(61%)
CHO
N
N
NCH3
N
O
5a
5b
5c
5d
5e
5f
12
5g
5h
(85%)
(69%)
(69%)
(59%)
(49%)
(67%)
(67%)
(64%)
o
Scheme 1. Reagents and reaction conditions: (a) 16% aq. HCl, 100 C, 24 h (68%); (b) 1-amino-
pyrrolidine hydrochloride (4.0 equiv.), AcONa (8.0 equiv.), MeOH, RT, 5 h (crude); (c) 2-
aminothiazole (4.0 equiv.), EDC (2.0 equiv.), DMAP (catalytic amounts), CH2Cl2, RT, 5 h (2 steps,
13%); (d) 1-amino-pyrrolidine hydrochloride (3.0 equiv.), Et3N (3.0 equiv.), THF, reflux, 3 d, then
SiO2 column chromatography (40%, polar isomer); (e) 2M aq. NaOH, EtOH, RT, 4 h (81%); (f)
heteroarylamine (1.5-3.0 equiv.), EDC·HCl (1.5 equiv.), DMAP (1.5 equiv.), CH2Cl2, RT, 24 h; (g)
heteroarylamine hydrochloride (3.0 equiv.), EDC (1.5 equiv.), DMAP (1.5 equiv.), CH2Cl2, RT, 24 h;
(h) 1-substituted piperazine (2.4 equiv.), sodium tri-acetoxy borohydride (3.0 equiv.), CH2Cl2, RT, 20
11

h.
Table 1. SAR exploration of hydrazone derivatives.
GK activation
Maximum blood
Solubility in buffer
hERG inhibition
Compd
4a
Heteroaryl
glucose reduction b)
a)
EC50 (M
(g/mL) d)
IC50 (M)
*
N
5.60
0.42
0.041
2.40
0.16
0.22
1.17
0.70
1.92
N.A. c)
5.4
2.4
N.D. e)
S
*
*
N
N
5a
-36%
-37%
-19%
-45%
-32%
-41%
-41%
-42%
17.5
S
S
5b
5c
0.1
16.7
Cl
*
N
0.9
N.D. e)
5.3
*
*
N
5d
5e
7.7
S
S
N
N
1.2
>100
>100
16.9
Me
*
*
N
N
N
5f
6.5
S
S
Me
5g
345.0
78.0
N
N
Me
*
N
S
5h
>100
O
N
N
Me
a) EC50 was measured at 5 mM glucose.
b) C57BL/6J fasted mice, 10 mg/kg, p.o. vs vehicle control.
c) N.A. = Not active.
d) Solubility in pH 6.5 phosphate buffer was determined.
e) N.D. = Not determined.
12

Figure 2. Effect of 5h on blood glucose level in overnight fasted Sprague-Dawley (SD) rats. 5h or
vehicle (10% Gelucire) was orally administered to overnight fasted SD rats at 0 hour. Values are mean
± S.E.M. (n=5). **P<0.01, *P<0.05 vs. control (Dunnett’s method)
N
N
H
N
N
O
S
S
CH3
N
N
O
O
O
5h
GK EC50 1.92 M

No hERG inhibition
13

14