Glucosides with cyclic diarylpolynoid as novel C-aryl glucoside SGLT2 inhibitors

Article abstract of DOI:10.1016/j.bmcl.2011.04.063

Novel C-aryl glucoside SGLT2 inhibitors containing cyclic diarylpolynoid motif were designed and synthesized for biological evaluation. Alkylzinc bromides have been efficiently prepared by the direct insertion of zinc metal into alkyl bromides. The organozinc reagents underwent smooth Pd-catalyzed cross-coupling reactions. Subsequent ring closing metathesis using 2nd generation Grubbs catalyst successfully generated novel class of ansa-compounds. These glucosides with cyclic diarylpolynoids demonstrated moderate in vitro inhibitory activity against SGLT2 in this series to date (IC₅₀ = 59.5-103 nM).

Full text of DOI:10.1016/j.bmcl.2011.04.063

Bioorganic & Medicinal Chemistry Letters 21 (2011) 3759–3763
Contents lists available at ScienceDirect
Bioorganic & Medicinal Chemistry Letters
journal homepage: www.elsevier.com/locate/bmcl
Glucosides with cyclic diarylpolynoid as novel C-aryl glucoside SGLT2 inhibitors
⇑
Suk Youn Kang, Min Ju Kim, Jun Sung Lee, Jinhwa Lee
Research Center, Green Cross Corporation, 303 Bojeong-Dong, Giheung-Gu, Yongin, Gyeonggi-Do 446-770, Republic of Korea
a r t i c l e i n f o
a b s t r a c t
Article history:
Novel C-aryl glucoside SGLT2 inhibitors containing cyclic diarylpolynoid motif were designed and synthe-
sized for biological evaluation. Alkylzinc bromides have been efficiently prepared by the direct insertion of
zinc metal into alkyl bromides. The organozinc reagents underwent smooth Pd-catalyzed cross-coupling
reactions. Subsequent ring closing metathesis using 2nd generation Grubbs catalyst successfully gener-
ated novel class of ansa-compounds. These glucosides with cyclic diarylpolynoids demonstrated moderate
in vitro inhibitory activity against SGLT2 in this series to date (IC50 = 59.5–103 nM).
Received 27 January 2011
Revised 21 March 2011
Accepted 13 April 2011
Available online 28 April 2011
Key words:
SGLT
Ó 2011 Elsevier Ltd. All rights reserved.
Dapagliflozin
Diarylpolynoid
Glucoside
Diabetes
Diabetes has become an increasing concern to the world’s pop-
ulation. In 2010, approximately 285 million people around the
world will have diabetes, corresponding to 6.4% of the world’s
adult population, with a prediction that by 2030 the number of
people with diabetes will have grown to 438 million.1 Type 2 dia-
betes is the most common disorder of glucose homeostasis,
accounting for nearly 90–95% of all cases of diabetes.2
simultaneous transport of Na+ down a concentration gradient.3 It
is estimated that 90% of renal glucose reabsorption is facilitated
by SGLT2.4
Bristol-Myers Squibb has identified dapagliflozin 1 (Fig. 1), a
potent, selective SGLT2 inhibitor for the treatment of type 2 diabe-
tes.5–7 At present, dapagliflozin is the most advanced SGLT2 inhib-
itor in clinical trials and is expected to be the first SGLT2 inhibitor
to market.8 On the other hand, Mitsubishi Tanabe, in collaboration
with Johnson & Johnson, is developing canagliflozin 2, another
Sodium-dependent glucose cotransporters (SGLTs) couple the
transport of glucose against a concentration gradient with the
Cl
OEt
Me
O
O
HO
HO
F
S
HO
HO
OH
OH
OH
OH
2, canagliflozin
1, dapagliflozin
Cl
OEt
Cl
OEt
O
O
MeO
HO
O
HO
HO
OH
OH
OH
4, Pfizer's
OH
3, Lexicon's
Figure 1. Structures of C-aryl glucoside SGLT2 inhibitors.
⇑
Corresponding author. Tel.: +82 31 260 9892; fax: +82 31 260 9020.
E-mail address: jinhwalee@greencross.com (J. Lee).
0960-894X/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmcl.2011.04.063

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S. Y. Kang et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3759–3763
novel C-glucoside-derived SGLT2 inhibitor.9 In addition, Boehrin-
ger Ingelheim (BI 10773), Lexicon (LX4211), Astellas (ASP1941),
and Pfizer (code unknown) are reported to be in various phase of
clinical trials.10 Our efforts on identifying inhibitors that target
SGLT2 have been previously described.11
In the middle of exploring of SGLT2 inhibitors, two cyclic diaryl-
heptanoids, acerogenin A (5) and B (6) have been reportedly iso-
lated from the bark of Acer nikoense as inhibitors of SGLT.12
Although effects of acerogenins on SGLT inhibitory activity was
only moderate, these unique diarylheptanoid structure was very
similar with diaryl or heteroaryl part of reported SGLT2 inhibitors.
Thus, we expected that combination of cyclic diaryl formation and
structure of dapagliflozin could lead to novel potent SGLT2 inhibi-
tor analogs. These interests directed us to design ansa-structure 7
of C-aryl glucoside SGLT2 inhibitors as shown in Figure 2. Herein,
we report the synthesis and biological evaluation of glucosides
Cl
OEt
O
HO
HO
OH
1, dapagliflozin
OH
O
HO
X
Y
HO
OH
OH
7
O
OH
5, acerogenin A(X=H, Y=OH)
6, acerogenin B(X=OH, Y=H)
Figure 2. Design of novel C-glucosides bearing cyclic diarylpolynoid
Br
O
OTMS
Me
O
Br
O
O
a,b
O
O
+
HO
HO
I
TMSO
OTMS
OH
8
OTMS
OH
10
9
Br
O
Br
O
d
c
O
O
HO
HO
AcO
OH
AcO
OAc
11
12
OH
OAc
O
O
n
n
O
O
f,g
e
HO
AcO
HO
OH
AcO
OAc
13
14
OH
OAc
O
n
h
O
HO
HO
OH
15
OH
Scheme 1. Reagents and conditions: (a) i-PrMgCl.LiCl, THF, À78 °C; (b) MeSO3H, MeOH, rt; (c) Et3SiH, BF3ÁOEt2, CH3CN–CH2Cl2, À10 °C; (d) Ac2O, Et3N, DMAP, CH2Cl2, rt, 47%
(four steps); (e) (i) Br(CH2)2+nCH@CH2, Zn, I2, DMA, 80 °C, (ii) Pd(PPh3)4, rt, 34–72%; (f) 2nd generation Grubbs cat., (ClCH2)2, 80 °C, 21–46%; (g) NaOMe, MeOH, 67–81%; (h)
10% Pd/C, H2, MeOH, 36–56%.

S. Y. Kang et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3759–3763
3761
with cyclic diarylpolynoid as novel C-aryl glucoside SGLT2
inhibitors.
ring closing metathesis. The initial approach toward 13 involves
Suzuki coupling of 12 using alkenylboronic acid in the presence
of a suitable Pd(0) catalyst.16 However, despite rather extensive
experimentation, we were unable to effect the required coupling
reaction in a satisfactory manner. Some typical coupling condi-
tions invariably provided the desired products in merely low
yields. At this stage, we were intrigued by the possibility of
using alkylzinc reagents for Pd-catalyzed cross-coupling reac-
tions.17 Thus, treatment of alkenyl bromide with zinc dust
(1.5 equiv), activated with I2 (5 mol %) in DMA (N,N-dimethyl-
acetamide) provides the corresponding alkenylzinc bromide. Its
subsequent cross-coupling with phenylbromide 12 using a cata-
lytic amount of Pd(PPh3)4 proceeded smoothly to completion
within 4 h at room temperature. Under these conditions, divinyl
compounds 13 were routinely obtained in 34–72% yields.
Preparation of C-glucosides bearing the cyclic diarylpolynoid is
described in Scheme 1. Thus, treatment of 2-(4-(allyloxy)benzyl)-
1-bromo-4-iodobenzene (8)13 with isopropylmagnesium chloride
lithium chloride complex solution effected magnesium-halogen
exchange.14 Subsequently, the addition of the nascent magnesiated
aromatic compound to persilylated gluconolactone 9 produced a
mixture of the corresponding lactols. The lactols were then treated
with methanol in the presence of methanesulfonic acid to produce
the corresponding methyl acetal 10, concurrently desilylated. The
methyl acetals were reduced with triethylsilane and BF3 etherate
to afford 11.15 A mixture of alcohols 11 was then peracetylated
using acetic anhydride and triethylamine in the presence of DMAP
(4-(dimethylamino)pyridine), and subsequently was separated
through column chromatography to produce the requisite beta-
isomer 12 in 47% yield over four steps.
The stage was set for the key ring-closing metathesis to form
macrocycle. After rather extensive experimentation, we were de-
lighted to find out that treatment of divinyl 13 with 2nd generation
Grubbs catalyst (0.1 equiv) in 1,2-dichloroethane (0.01 M) at 80 °C
With the key bromide 12 in hand, focus shifted to the effi-
cient preparation of the divinyl compounds 13, precursors for
Table 1
In vitro inhibitory activity against hSGLT2
a
Compound
hSGLT2 IC50 (nM)
Dapagliflozin (1)
1.35 0.15b
O
0
O
14a
59.5
HO
HO
OH
OH
O
1
O
14b
89.6
HO
HO
OH
OH
O
2
O
14c
103
HO
HO
OH
OH
OH
OH
O
1
O
15a
81.9
HO
HO
OH
O
2
O
15b
99.7
HO
HO
OH
a
These data were obtained by single determinations.
The IC50 value was obtained by in-house multiple determinations.
b

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S. Y. Kang et al. / Bioorg. Med. Chem. Lett. 21 (2011) 3759–3763
6. Meng, W.; Ellsworth, B. A.; Nirschl, A. A.; McCann, P. J.; Patel, M.; Girotra, R. N.;
Wu, G.; Sher, P. M.; Morrison, E. P.; Biller, A. A.; Zahler, R.; Deshpande, P. P.;
Pullockaran, A.; Hagan, D. L.; Morgan, N.; Taylor, J. R.; Obermeier, M. T.;
Humphreys, W. G.; Khanna, A.; Discenza, L.; Robertson, J. G.; Wang, A.; Han, S.;
Wetterau, J. R.; Janovitz, E. B.; Flint, O. P.; Whaley, J. M.; Washburn, W. N. J. Med.
Chem. 2008, 51, 1145–1149.
for 72 h provided the desired macrocycles in moderate yields
(21–46%).18 The geometric isomers were inseparable (E/Z =
2.5–3.0/1 based on 1H NMR analysis). Subsequently, hydrolysis of
13 using NaOMe in methanol produced the corresponding deacet-
ylated compounds 14 in good yields (67–81%). Finally, hydrogena-
tion of 14 on 10% Pd/C in methanol generated the corresponding
macrocycles 15 uneventfully.
7. Washburn, W. N. J. Med. Chem. 2009, 52, 1785–1794.
8. According to a report from Business Wire on June 26, 2010, dapagliflozin as add
on therapy to insulin demonstrated improved glycemic control in patients with
type 2 diabetes inadequately controlled with insulin.
9. Nomura, S.; Sakamaki, S.; Hongu, M.; Kawanshi, E.; Koga, Y.; Sakamoto, T.;
Yamamoto, Y.; Ueta, K.; Kimata, H.; Nakayama, K.; Tsuda-Tsukimoto, M. J. Med.
Chem. 2010, 53, 6355–6360.
The cell-based SGLT2 AMG (Methyl-a-D-glucopyranoside) inhi-
bition assay was performed to evaluate the inhibitory effects of all
prepared compounds on hSGLT2 activities.19,20 Table 1 shows the
structure–activity relationship upon alteration on the ring size of
ansa-macrocycles. The smallest ring 14a showed the moderate
inhibitory activity against hSGLT2 (IC50 = 59.5 nM). As the ring size
increases, the in vitro inhibitory activity gradually decreases as
exemplified by compounds 14b and 14c (IC50 = 89.6 nM for 14b,
IC50 = 103 nM for 14c), suggesting that bulky macrocyclic diaryl-
polynoid is not so favorable for overall in vitro inhibitory activity
against hSGLT2. Also saturated macrocycles 15a and 15b proved
to maintain the similar level of inhibitory activity against hSGLT2
to that of the corresponding parent molecules.23,24
In summary, although effects of acerogenins on SGLT inhibitory
activity were reported to be only moderate, our interest of SGLT
inhibition for cyclic diaryl compound combined with structure of
potent dapagliflozin led to design ansa-structure 7 of C-aryl gluco-
side SGLT2 inhibitors. We successfully performed the synthesis of
C-glucosides associated with cyclic diarylpolynoid utilizing versa-
tile organozinc chemistry and subsequent ring-closing olefin
metathesis using 2nd generation Grubbs catalyst. The synthesized
ansa-analogs were subsecutively subjected to biological evaluation
as novel C-aryl glucoside SGLT2 inhibitors. All of the analogs tested
showed the modest in vitro inhibitory activity against hSGLT2
(14a, IC50 = 59.5 nM).
10. (a) Boehringer Ingelheim Pharmaceuticals, www.clinicaltrials.gov, 2010,
NCT01164501.; (b) Lexicon Pharmaceuticals, www.clinicaltrials.gov, 2009,
NCT00962065.; (c) Astellas Pharma Inc., www.clinicaltrials.gov, 2010,
NCT01135433.; (d) Mascitti, V. Presented at the 240th American Chemical
Society National Meeting and Exposition, Boston, MA, August 22–26, 2010;
Medi-151.
11. (a) Lee, J.; Lee, S.-H.; Seo, H. J.; Son, E.-J.; Lee, S. H.; Jung, M. E.; Lee, M.; Han, H.-
K.; Kim, J.; Kang, J.; Lee, J. Bioorg. Med. Chem. 2010, 18, 2178; (b) Kim, M. J.; Lee,
J.; Kang, S. Y.; Lee, S.-H.; Son, E.-J.; Jung, M. E.; Lee, S. H.; Song, K.-S.; Lee, M.;
Han, H.-K.; Kim, J.; Lee, J. Bioorg. Med. Chem. Lett. 2010, 20, 3420; (c) Kang, S. Y.;
Song, K.-S.; Lee, J.; Lee, S.-H.; Lee, J. Bioorg. Med. Chem. 2010, 18, 6069; (d) Lee,
J.; Kim, J. Y.; Choi, J.; Lee, S.-H.; Kim, J.; Lee, J. Bioorg. Med. Chem. Lett. 2010, 20,
7046; (e) Park, E.-J.; Kong, Y.; Lee, J. S.; Lee, S.-H.; Lee, J. Bioorg. Med. Chem. Lett.
2011, 21, 742; (f) Song, K.-S.; Lee, S. H.; Kim, M. J.; Seo, H. J.; Lee, J.; Lee, S.-H.;
Jung, M. E.; Son, E.-J.; Lee, M.; Kim, J.; Lee, J. ACS Med. Chem. Lett. 2011, 2, 182–
187.
12. Morita, H.; Deguchi, J.; Motegi, Y.; Sato, S.; Aoyama, C.; Takeo, J.; Shiro, M.;
Hirasawa, Y. Bioorg. Med. Chem. Lett. 2010, 20, 1070.
13. Preparation of 2-(4-(allyloxy)benzyl)-1-bromo-4-iodobenzene (8): To a mixture of
2-bromo-5-iodo-benzoic acid (25 g, 76.5 mmol) in CH2Cl2 (80 ml) were added
(COCl)2 (9 ml) and DMF (0.5 ml). The reaction mixture was stirred for 14 h at rt,
and all volatile constituents were removed on rotary evaporator in vacuo. The
residue was dissolved in CH2Cl2 (50 ml), and the resultant solution was cooled to
0 °C. After addition of anisole (23 ml) to the mixture, AlCl3 (12.5 g) was added
portionwise not to exceed 10 °C. The solution was stirred at rt for overnight and
then poured into ice. The organic phase was separated off, and aqueous phase
was extracted with CH2Cl2 twice. After drying organic phases with MgSO4, the
volatile
The crude product was purified with BiotageÒ to afford (2-bromo-5-
iodophenyl)(4-methoxyphenyl)methanone (25.8 g, 81%) as light yellow
solid. solution of (2-bromo-5-iodophenyl)(4-methoxyphenyl)methanone
compound
was
evaporated
in
vacuo.
a
A
(10 g, 24 mmol) and triethylsilane (TESH, 15.3 ml, 96 mmol) in a mixture of
CH2Cl2 (30 ml) and CH3CN (60 ml) is cooled to 0 °C. Then with stirring, BF3
etherate (5.0 ml, 36 mmol) was added slowly. The solution was stirred for 14 hr
at rt. Thesolutionwasstirred foradditional3hr at50ꢀ60 °Candthencooled tort.
The resulting solution was quenched with aqueous KOH solution (50 ml) and the
aqueous layer was extracted with ethyl acetate. After solvent was evaporated,
the residue was purified with column chromatography to produce 1-bromo-4-
iodo-2-(4-methoxybenzyl)benzene (6.96 g, 72%) as colorless oil. To a solution of
1-bromo-4-iodo-2-(4-methoxybenzyl)benzene (7.5 g, 18.6 mmol) in CH2Cl2
(50 ml) at 0 °C was added BBr3 in CH2Cl2 (1.0 M, 37.5 ml) dropwise, and the
reaction solution was then stirred for 3 h at rt. The resulting solution was
quenched with MeOH and the volatile constituents were removed on rotary
evaporator. The residue was purified with BiotageÒ to afford 4-(2-bromo-5-
iodobenzyl)phenol (6.7 g, 92%) as a white solid. To a mixture of 4-(2-bromo-5-
iodobenzyl)phenol (6.7 g, 17.2 mmol) and K2CO3 (9.5 g, 68.8 mmol) in CH3CN
(50 ml) was added allylbromide (3.2 ml, 37 mmol). The reaction mixture was
stirred for 24 hr at rt. After filteration of insoluble compounds, the filtrate was
evaporated, and the residue was purified with BiotageÒ to produce 2-(4-
(allyloxy)benzyl)-1-bromo-4-iodobenzene (6.9 g, 95%) as colorless oil. 1H NMR
(CDCl3) d 7.46 (d, J = 2.4 Hz, 1H), 7.41 (dd, J = 8.4, 2.0 Hz, 1H), 7.29 (s, 1H), 7.13–
7.11 (m, 2H), 6.91–6.89 (m, 2H), 6.13–6.06 (m, 1H), 5.47–5.43 (m, 1H), 5.34–5.31
(m, 1H), 5.55 (dt, J = 5.2, 2.0 Hz, 2H). MH+ 429.
Acknowledgments
This letter is dedicated to Dr. Yoshito Kishi, a Harvard Univer-
sity chemistry professor on the occasion of recent U.S. approval
of Eisai Co.’s Halaven. We appreciate Dr. Eun Chul Huh for his lead-
ership as Head of R&D, Green Cross Corporation (GCC). We are also
thankful to Dr. Jeongmin Kim and Mr. Sung-Han Lee for their help-
ful discussions.
References and notes
1. International Diabetes Federation International Diabetes Federation. Diabetes
Atlas, 4th ed.; International Diabetes Federation: Montreal, Canada, 2009.
2. Dwarakanathan, A. J. Insur. Med. 2006, 38, 20–30.
3. Mackenzie, B.; Loo, D. D. J. Biol. Chem. 1996, 20, 32678–32683.
4. Moe, O. W.; Berry, C. A.; Rector, F. C. In The Kidney; Brenner, B. M., Rector, F. C.,
Eds., 5th ed.; WB Saunders Co.: Philadelphia, 2000; pp 375–415.
5. Ellsworth, B. A.; Meng, W.; Patel, M.; Girotra, R. N.; Wu, G.; Sher, P.; Hagan, D.;
Obermeier, M.; Humphreys, W. G.; Robertson, J. G.; Wang, A.; Han, S.; Waldron,
T.; Morgan, N. N.; Whaley, J. M.; Washburn, W. N. Bioorg. Med. Chem. Lett. 2008,
18, 4770–4773.
14. Krasovsky, A.; Knochel, P. Angew. Chem., Int. Ed. 2004, 43, 3333.
15. Ellsworth, B. A.; Doyle, A. G.; Patel, M.; Caceres-Cortes, J.; Meng, W.;
Deshpande, P. P.; Pullockaran, A.; Washburn, W. N. Tetrahedron: Asymmetry
2003, 14, 3242.

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temperature) and then the radioactivity was measured using
3763
16. Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457.
a
liquid
17. Huo, S. Org. Lett. 2003, 4, 423.
18. Trnka, T. M.; Grubbs, R. H. Acc. Chem. Res. 2001, 34, 18.
scintillation counter. IC50 was determined by nonlinear regression analysis
using GraphPad PRISM.21,22
19. For cloning and cell line construction for human SGLT2, human SGLT2
(hSGLT2) gene was amplified by PCR from cDNA-Human Adult Normal
Tissue Kidney (Invitrogen, Carlsbad, CA). The hSGLT2 sequence was cloned
into pcDNA3.1(+) for mammalian expression and were stably transfected into
chinese hamster ovary (CHO) cells. SGLT2-expressing clones were selected
based on resistance to G418 antibiotic (GeneticinÒ, Invitrogen, Carlsbad, CA)
21. Han, S.; Hagan, D. L.; Taylor, J. R.; Xin, L.; Meng, W.; Biller, S. A.; Wetterau, J. R.;
Washburn, W. N.; Whaley, J. M. Diabetes 2008, 57, 1723.
22. Katsuno, K.; Fujimori, Y.; Takemura, Y.; Hiratochi, M.; Itoh, F.; Komatsu, Y.;
Fujikura, H.; Isaji, M. J. Pharmacol. Exp. Ther. 2007, 320, 323.
23. Initially, we expected that the novel series of designed compounds would be
able to provide potent inhibition against hSGLT2, showing synergistic effect by
macrocyclization. Although these current compounds appear to show only
moderate inhibition activity, the authors think that this series hinted valuable
possibilities about combination of two different structures. As a matter of fact,
we have identified much more potent series of macrocycles as SGLT2 inhibitors
in house by extending conceptually from this series.
24. In this communication, SGLT2 inhibiton data were obtained by single
determinations. Whenever we evaluate our new compounds against hSGLT2,
dapagliflozin was also included as a reference compound. The SGLT2 inhibition
for dapagliflozin has shown a certain number in the close range in each
different assay. Thus, we believe that all SAR discussions in the manuscript are
scientifically valid.
and activity in the 14C- -glucopyranoside (14C-AMG) uptake assay.
a-methyl-D
20. For sodium-dependent glucose transport assay, cells expressing hSGLT2 were
seeded into a 96-well culture plate at a density of 5 Â 104 cells/well in RPMI
medium 1640 containing 10% fetal bovine serum. The cells were used 1 day
after plating. They were incubated in pretreatment buffer (10 mM HEPES,
5 mM Tris, 140 mM choline chloride, 2 mM KCl, 1 mM CaCl2, and 1 mM MgCl2,
pH 7.4) at 37 °C for 10 min. They were then incubated in uptake buffer (10 mM
HEPES, 5 mM Tris, 140 mM NaCl, 2 mM KCl, 1 mM CaCl2, 1 mM MgCl2, and
1 mM 14C-nonlabeled AMG pH 7.4) containing 14C-labeled (8
lV) and inhibitor
or dimethyl sulfoxide (DMSO) vehicle at 37 °C for 2 h. Cells were washed twice
with washing buffer (pretreatment buffer containing 10 mM AMG at room