Indole-glucosides as novel sodium glucose co-transporter 2 (SGLT2) inhibitors. Part 2

Article abstract of DOI:10.1016/j.bmcl.2005.12.006

A series of indole-O-glucosides and C-glucosides was synthesized and evaluated in SGLT1 and SGLT2 cell-based functional assays. Compounds 2a and 2o were identified as potent SGLT2 inhibitors and screened in ZDF rats.

Full text of DOI:10.1016/j.bmcl.2005.12.006

Bioorganic & Medicinal Chemistry Letters 16 (2006) 1696–1701
Indole-glucosides as novel sodium glucose co-transporter 2
(SGLT2) inhibitors. Part 2
Xiaoyan Zhang,* Maud Urbanski, Mona Patel, Geoffrey G. Cox, Roxanne E. Zeck,
Haiyan Bian, Bruce R. Conway, Mary Pat Beavers, Philip J. Rybczynski
and Keith T. Demarest
Johnson & Johnson Pharmaceutical Research and Development, L.L.C., 1000 Rt. 202, PO Box 300, Raritan, NJ 08869, USA
Received 21 October 2005; revised 1 December 2005; accepted 2 December 2005
Available online 27 December 2005
Abstract—A series of indole-O-glucosides and C-glucosides was synthesized and evaluated in SGLT1 and SGLT2 cell-based
functional assays. Compounds 2a and 2o were identified as potent SGLT2 inhibitors and screened in ZDF rats.
Ó 2006 Published by Elsevier Ltd.
Non-insulin-dependent diabetes mellitus (NIDDM) is a
metabolic disorder characterized by hyperglycemia as
well as insulin resistance and/or impaired insulin secre-
tion. Normalization of plasma glucose in NIDDM pa-
tients would be predicted to improve insulin action
and to offset the development of diabetic complications.
An inhibitor of the sodium-glucose co-transporters
(SGLTs) in the kidney would be expected to aid in the
normalization of plasma glucose levels by enhancing
glucose excretion.1 Multiple classes of glucose conju-
gates and C-glucosides have been reported as SGLT
inhibitors.2 Compound 1 has been reported to lower
blood glucose levels by inhibiting both SGLT1 and
SGLT2, the two major isoforms of SGLT in the human
body.3 In our earlier studies, we demonstrated that mod-
ification of the benzofuran moiety of compound 1
resulted in compounds with potent SGLT2 inhibitory
activity similar to that of compound 1, but highly selec-
tive for SGLT2 over SGLT1.4 Further modification of
the ketone/phenol moiety of compound 1 to benzo-fused
heteroaromatic rings led to the identification of a series
of novel heteroaryl-O-glucosides as potent SGLT2
inhibitors.5 A good example from this series is indole
analog 2a (Fig. 1), which showed in vitro SGLT2 inhib-
itory activity and selectivity similar to that of compound
1. We have continued SAR studies of compound 2a by
A
B
C
OH
O
O
HN
6'
O
O
H3C
O
4'
OH
OH
OH
OH
O
O
HO
HO
OH
OH
1
2a
Figure 1.
varying the carbon chain length (region B) and replacing
the dihydrobenzofuran moiety with other aromatic rings
(region C). We report herein a series of novel indole-
O-glucosides that are selective inhibitors of SGLT2.
Indole-C-glucosides are a logical extension of the O-glu-
cosides, and we report our progress in this area as well
(Fig. 2, compounds 3 and 4).
All of the indole-O-glucosides 2a–2v were synthesized
from the corresponding indole aglycones 5. The two-
carbon linker indoles 5 (n = 2) were prepared following
the synthetic route previously described.5 Preparation
of indoles 5a–d is outlined in Schemes 1 and 2.
As illustrated in Scheme 1, the aglycones 5a–b were
constructed by addition of a commercially available
Grignard reagent to indole-3-carbaldehyde 7 or by
Keywords: SGLT; Glucosides.
*
Corresponding author. Tel.: +1 908 704 5232; fax: +1 908 203
4861; e-mail: xzhang11@prdus.jnj.com
0960-894X/$ - see front matter Ó 2006 Published by Elsevier Ltd.
doi:10.1016/j.bmcl.2005.12.006

X. Zhang et al. / Bioorg. Med. Chem. Lett. 16 (2006) 1696–1701
1697
O
Et
HN
HN
S
Br
Ph
N
a, b
c, d
O
OCH3
O
OH
OH
Et
O
HN
OCH3
HO
9b
11
OH
O
O
O
3
OH
OH
O
S
S
Ar'
Ph
Ar'
Ph
N
N
HO
Et
O
O
HN
e
OH
OCH3
8c
OH
2o
5d
OH
OH
O
HO
Scheme 2. Reagents and conditions: (a) 4-BrPhCOCl, CH2Cl2, AlCl3;
(b) PhSO2Cl, Bu4NBr (cat.), PhH, 25% aq NaOH; (c) NaBH4, TFA,
CH2Cl2; (d) Ar0B(OH)2, PdCl2(dppf)2, CsF, CH3OCH2CH2OCH3,
72 °C; (e) BBr3, CH2Cl2, ꢀ78 °C to rt.
OH
4
Figure 2.
indole 9b introduced a 4-bromophenyl group, which
was further coupled with an arylboronic acid under
standard Suzuki coupling conditions to provide biaryl
intermediate 8c. Deprotection of the phenol gave 5d.
generation of indolemagnesium bromide from com-
pound 10 followed by addition to an aryl aldehyde.
The indolecarbinols generated by either pathway were
deoxygenated with triethylsilane and tin (IV) chloride
to give 3-alkylindoles 8a–b in excellent yield.6 Deprotec-
tion of the phenol yielded 5a–b. Indole 5c was accessed
by Suzuki coupling of iodoindole 10 followed by depro-
tection of the phenol group.7
Finally, glucosides 2a–2v were synthesized by conjugat-
ing indoles 5 with 2,3,4,6-tetra-O-acetyl-a-D-glucopyr-
anosyl bromide using the conditions as previously
described (Scheme 3).5
Target compounds were screened in the cell-based
SGLT functional assays.8 Exploration of the SAR be-
gan by replacing the dihydrobenzofuran moiety of com-
pound 2a with other aromatic groups (Fig. 1, region C).
Previous SAR studies of compound 1 showed that ben-
zofuran can be replaced with aromatics such as benzodi-
oxanyl, naphthyl or 4-ethoxyphenyl with retention of
good SGLT2 inhibitory activity.4 However, as shown
in Table 1, replacement of 2,3-dihydrobenzofuran
moiety of 2a resulted in compounds 2b–2f which were
at least 5-fold less potent against SGLT2. Thus, this line
of SAR was abandoned.
Scheme 2 describes the synthesis of indole aglycones 5d
containing a biaryl moiety. Friedel–Crafts acylation of
O
Et2N
HN
N
a
CHO
OBn
CHO
OBn
6
7
b, c
P
P
N
N
d
Ar
Ar
We next studied the carbon-chain linker (Fig. 1, region
B) and the data are presented in Table 2. Truncation
of the linker in 2a by one carbon provided analog 2g
with significant loss of SGLT2 inhibitory activity. How-
ever, modification of 2,3-dihydrobenzofuran in com-
pound 2g with other aromatic groups provided several
OBn
OH
5a P = CON(Et)2
5b P = SO2Ph
8a P = CON(Et)2
8b P = SO2Ph
g, h, c
O
S
O
S
HN
P
HN
Ph
Ph
i, d
N
Ar
e, f
N
N
O
O
a, b
n
Ar
I
n
O
OBn
OH
OCH3
OBn
OH
OH
OH
O
9a
5
HO
10
5c
OH
P = CON(Et)2 or SO2Ph
n = 0, 1 or 2
Scheme 1. Reagents and conditions: (a) N,N-diethylcarbamoyl chlo-
ride, NaH, THF; (b) ArMgBr, THF, 0 °C; (c) Et3SiH, SnCl4, CH2Cl2,
ꢀ78 °C, 20 min; (d) H2 (14 psi), 10% Pd/C, EtOAc/EtOH; (e) ICl, Py,
CH2Cl2; (f) PhSO2Cl, Bu4NBr (cat.), PhH, 25% aq NaOH; (g)
EtMgBr, THF; (h) ArCHO, THF, rt; (i) 4-MeOPhB(OH)2,
PdCl2(dppf)2, CsF, CH3OCH2CH2OCH3, 72 °C.
2
Scheme 3. Reagents and conditions: (a) 2,3,4,6-tetra-O-acetyl-a-D-
glucopyranosyl bromide, K2CO3, acetone; (b) 25% aq KOH, EtOH,
reflux.

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X. Zhang et al. / Bioorg. Med. Chem. Lett. 16 (2006) 1696–1701
Table 1. In vitro SGLT inhibition
HN
Ar
O
OH
O
HO
OH
OH
Compound
Ar
SGLT1 IC50 SEM (lM)
SGLT2 IC50 SEM (lM)
1
—
0.139 0.013
0.011 0.002
2aa
2b
0.145 0.011
0.024 0.004
0.121 0.021
0.201 0.037
0.163 0.019
0.202 0.013
50%b
O
O
3.61 0.16
O
2c
1.1 0.028
2da
2e
OCH3
OC2H5
C2H5
0.611 0.091
1.19 0.103
46%b
2f
a See Ref. 5.
b Inhibition at a screening concentration of 10 lM.
potent SGLT2 inhibitors. The most interesting com-
pound among this series is compound 2o, which has
the same SGLT2 inhibitory activity as compound 2a.
By comparison, the two-carbon linker analog 2f exhibit-
ed much weaker SGLT2 inhibitory activity. In some
cases, shortening the linker did not result in significant
changes in SGLT2 inhibitory activity, such as 2c versus
2h, 2d versus 2i, and 2e versus 2k. However, the one-car-
bon linker analogs showed higher selectivity for SGLT2
versus SGLT1. Further truncation of the carbon-chain
linker of compound 2i provided compound 2v with a
much weaker SGLT2 inhibitory activity.
One drawback of compound 1 as an oral anti-diabetic
agent is inactivation via conversion to its aglycone by
intestinal b-glucosidase.3a Instability toward b-glucosi-
dase is also a potential problem for the indole-O-gluco-
sides. One solution to this problem is the construction of
C-glucosides, 3 and 4 (Fig. 2), based on compound 2o.
This strategy has been reported in the literature.2e
Scheme 4 depicts the synthesis of C-glucosides 3 and
4.10 Bromoindoles 12 and 15 were elaborated to com-
pounds 14a and 14b, respectively.11 Stereoselective C-
glucosylation was accomplished in two steps. First,
conversion of the bromoindoles 14a–b to the organoli-
thium derivatives and addition to 2,3,4,6-tetra-O-ben-
zyl-D-glucopyranolactone provided the corresponding
lactols. Second, reduction of the lactols with triethylsi-
lane and boron trifluoride etherate set the new stereo-
center in 17a–b.12 Debenzylation provided the desired
products 3 and 4.
The SGLT2 selective inhibitor 2o and SGLT1/SGLT2
mixed inhibitor 2a were evaluated by iv administration
in male Zucker Diabetic Fatty (ZDF) rats. The effects
on urinary glucose excretion and the pharmacokinetic
properties were measured and the results are summa-
rized in Table 3.9 When a 3 mg/kg dose was adminis-
tered iv, both compounds showed pharmacokinetic
profiles similar to that of compound 1. Compounds 2a
and 2o had similar efficacy toward urinary glucose
excretion in spite of their different in vitro selectivity
profiles. Unfortunately, the efficacy of neither com-
pound exceeded that of compound 1. Finally, com-
pounds 2a and 2o suffered from short half-life and
rapid clearance, which precluded further development
of this series.
In vitro examination of C-glucosides 3 and 4 in the cell-
based SGLT functional assay indicated that both com-
pounds were inactive at SGLT1. Compound 3 showed
only 12% inhibition of SGLT2 at a screening concentra-
tion of 10 lM. Compound 4 had a functional IC50 value
of 0.132 lM at SGLT2. These data suggests the impor-
tance of the glycosidic oxygen in this series of SGLT
inhibitors.

X. Zhang et al. / Bioorg. Med. Chem. Lett. 16 (2006) 1696–1701
1699
Table 2. In vitro SGLT inhibition
HN
HN
Ar
O
O
OCH3
OH
OH
OH
OH
O
O
HO
HO
OH
OH
2g – 2u
2v
Compound
Ar
SGLT1 IC50 SEM (lM)
SGLT2 IC50 SEM (lM)
2g
30%a
1.87b
O
2h
2i
68%a
0.293 0.045
0.121 0.014
0.143 0.029
0.094 0.022
0.052 0.011
0.066 0.009
0.099 0.022
0.028 0.004
0.119 0.042
0.296 0.042
0.089 0.021
0.182 0.048
1.51 0.174
79%a
OCH3
F
2j
OCH3
2k
2l
49%a
OC2H5
2.89 0.473
4.39 0.358
42%a
SCH3
CH3
2m
2n
2o
2p
2q
2r
2s
F
CH3
2.14 0.016
C2H5
3.2b
nPr
Cl
58%a
63%a
Ph
F
35%a
Ph
2t
2.24 0.245
1.97 0.599
0%a
0.050 0.011
0.143 0.007
37%a
S
N
2u
2v
Structure at the top of the table
a Inhibition at a screening concentration of 10 lM.
b The compound had one IC50 determination.

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X. Zhang et al. / Bioorg. Med. Chem. Lett. 16 (2006) 1696–1701
Table 3. In vivo urinary glucose excretion and pharmacokinetic
profiles of SGLT2 inhibitors in ZDF ratsa
2001, 7, 417; (e) Zhou, L.; Cryan, E. V.; D’Andrea, M. D.;
Belkowski, S.; Conway, B. R.; Demarest, K. T. J. Cell.
Biochem. 2003, 90, 339.
Compound Glucosuria AUC (nM h) T1/2
(h)
Clp
(mL/min/kg)
2. (a) Ohsumi, K.; Matsueda, H.; Hatanaka, T.; Hirama, R.;
Umemura, T.; Oonuki, A.; Ishida, N.; Kageyama, Y.;
Maezono, K.; Kondo, N. Bioorg. Med. Chem. Lett. 2003,
13, 2269; (b) Nishimura, T.; Fujikura, H.; Fushimi, N.;
Tatani, K.; Katsuno, K.; Isaji, M. WO03/000712, 2003;
Chem. Abstr. 2003, 138, 49945; (c) Nishimura, T.; Fush-
imi, N.; Fujikura, H.; Katsuno, K.; Komatsu, Y.; Isaji, M.
WO02/068439; Chem. Abstr. 2002, 137, 232854; (d)
Fujikura, H.; Fushimi, N.; Nishimura, T.; Tatani, K.;
Katsuno, K.; Hiratochi, M.; Tokutake, Y.; Isaji, M.
WO01/68660; Chem. Abstr. 2003, 135, 242456; (e) Wash-
burn, W. N.; Ellsworth, B.; Meng, W.; Wu, G.; Sher, P.
M. US 03/0114390; Chem. Abstr. 2003, 139, 36736; (f)
Link, J. T.; Sorensen, B. K. Tetrahedron Lett. 2000, 41,
9213.
(mg/4 h)
1
244 114
148 63
155 87
2087 335
2460 326
1992 154
0.97 53.1 7.9
0.67 46.6 4.8
0.86 61.0 4.8
2a
2o
a Dose, iv 3.0 mpk.
O
TBS
N
S
Ph
NH
N
O
c, d, e
Ar
a, b
Ar
Br
O
Br
Br
12
13
14a
3. (a) Tsujihara, K.; Hongu, M.; Saito, K.; Kawanishi, H.;
Kuriyama, K.; Matsumoto, M.; Oku, A.; Ueta, K.; Tsuda,
M.; Saito, A. J. Med. Chem. 1999, 42, 5311; (b) Ueta, K.;
Ishihara, T.; Matsumoto, Y.; Oku, A.; Nawano, M.;
Fujita, T.; Saito, A.; Arakawa, K. Life Sci. 2005, 76, 2655;
(c) Tazawa, S.; Yamato, T.; Fujikura, H.; Hiratochi, M.;
Itoh, F.; Tomae, M.; Takemura, Y.; Maruyama, H.;
Sugiyama, T.; Wakamatsu, A.; Isogai, T.; Isaji, M. Life
Sci. 2005, 76, 1039.
4. Dudash, J., Jr.; Zhang, X.; Zeck, R. E.; Johnson, S. G.;
Cox, G. G.; Conway, B. R.; Rybczynski, P. J.; Demarest,
K. T. Bioorg. Med. Chem. Lett. 2004, 14, 5121.
5. Zhang, X.; Urbanski, M.; Patel, M.; Zeck, R. E.; Cox, G.
G.; Bian, H.; Conway, B. R.; Rybczynski, P. J.; Demarest,
K. T. Bioorg. Med. Chem. Lett. 2005, 15, 5202.
O
TBS
O
N
Et2N
N
Et2N
Ar
N
h, e
f, g
Ar
CHO
Br
Br
Br
16
15
14b
HN
TBS
N
Ar
Ar
TBS
N
k, l
i, j
Ar
OBn
OBn
OH
OH
O
O
BnO
HO
Br
6. Comins, D. L.; Stroud, E. D. Tetrahedron Lett. 1986, 27,
1869.
OBn
OH
3, 4 Ar =
7. All compounds provided satisfactory spectral data (1H
NMR, LCMS) and were homogeneous by TLC. Full
experimental details on individual compounds can be
found in Beavers, M.P.; Patel, M.; Urbanski, M.; Zhang,
X. WO05/012243A2; Chem. Abstr. 2005, 142, 219489.
8. CHO-K1 cells overexpressing human SGLT2 or SGLT1
were used for the cell-based functional screens. Cells were
treated with compound in the absence or presence of NaCl
for 15 min. Cells were then labeled with 14C a-methylg-
lucopyranoside (AMG)—a non-metabolizable glucose
analog specific for sodium-dependent glucose transport-
ers. After 2 h the labeled cells were washed three times
with ice-cold PBS. Cells were then solubilized and Na-
dependent 14C AMG uptake was quantified by measuring
radioactivity.
14a-b
17a-b
Et
Scheme 4. Reagents and conditions: (a) ArCOCl, AlCl3, CH2Cl2; (b)
PhSO2Cl, Bu4NBr (cat.), PhH, 25% aq NaOH; (c) t-BuNH2–BH3,
AlCl3, CH2Cl2, 0 °C; (d) 50% aq NaOH, THF, reflux; (e) NaH, TBSCl,
THF, 0 °C to rt; (f) ArMgBr, THF, 0 °C; (g) Et3SiH, SnCl4, CH2Cl2,
ꢀ78 °C, 20 min; (h) 25% aq NaOH, EtOH, reflux; (i) t-BuLi (2 equiv),
2,3,4,6-tetra-O-benzyl-D-gluconolactone, THF, ꢀ78 °C; (j) Et3SiH,
BF3ÆEt2O, CH3CN, ꢀ30 °C; (k) 25% aq NaOH, THF, reflux; (l) H2
(14 psi), Pearlman’s cat., EtOAc, EtOH.
In summary, the SAR study of indole-O-glucosides ex-
tends our previous work. Several potent SGLT2 inhibi-
tors were identified with a range of SGLT1/SGLT2
selectivity. The reduced biological activity of the C-glu-
cosides suggests the importance of the anomeric oxygen
to SGLT inhibitory activity. The important questions as
to the functional significance of SGLT1 in the kidney
and the consequence of SGLT subtype selectivity are
the subject of ongoing studies.
9. Male Zucker Diabetic Fatty (ZDF) rats (7–8 weeks) were
obtained from Charles River. Animals were maintained
on a 12 h light/dark cycle in a temperature-controlled
room. Animals were given ad libitum access to food
(standard rodent diet Purina 5008) and water. Animals
were fasted for 12 h prior to initiation of the experiment.
On the morning of the experiment, animals were admin-
istered (10% Solutol) or compound (2 mL/kg) by intra-
venous injection. After 1 h, animals received an oral
glucose challenge (4 mL/kg of 50% solution) and were
immediately placed in metabolism cages. Animals were
given free access to water and urine was collected for 4 h.
Urinary glucose was quantified using the Trinder Reagent
(Sigma).
References and notes
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10. All compounds provided satisfactory spectral data (1H
NMR, LCMS) and were homogeneous by TLC. Full
experimental details on individual compounds can be
found in Rybczynski, P.; Urbanski, M; Zhang, X. WO05/
012318A2; Chem. Abstr. 2005, 142, 219490.

X. Zhang et al. / Bioorg. Med. Chem. Lett. 16 (2006) 1696–1701
1701
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