Synthesis of new six- and seven-membered 1-N-iminosugars as promising glycosidase inhibitors

Article abstract of DOI:10.1016/j.bmc.2011.07.059

New six- and seven-membered 1-N-iminosugars were prepared from d-glucose by the stereoselective Michael addition of nitromethane to d-glucose derived α,β-unsaturated ester A followed by one pot reduction of nitro/ester functionality and subsequent amine p

Full text of DOI:10.1016/j.bmc.2011.07.059

Bioorganic & Medicinal Chemistry 19 (2011) 5912–5915
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Bioorganic & Medicinal Chemistry
journal homepage: www.elsevier.com/locate/bmc
Synthesis of new six- and seven-membered 1-N-iminosugars as promising
glycosidase inhibitors
Amit M. Jabgunde a, Navnath B. Kalamkar a, Sanjay T. Chavan b, Sushma G. Sabharwal b, Dilip D. Dhavale a,
⇑
a Garware Research Centre, Department of Chemistry, University of Pune, Pune 411 007, India
b Division of Biochemistry, Department of Chemistry, University of Pune, Pune 411 007, India
a r t i c l e i n f o
a b s t r a c t
Article history:
New six- and seven-membered 1-N-iminosugars were prepared from
D
-glucose by the stereoselective
Received 2 June 2011
Revised 28 July 2011
Accepted 29 July 2011
Available online 4 August 2011
Michael addition of nitromethane to D-glucose derived a,b-unsaturated ester A followed by one pot reduc-
tion of nitro/ester functionality and subsequent amine protection to get N-Cbz protected aminol 6. Hydro-
lysis of 1,2-acetonide and reductive aminocyclization gave seven membered 1-N-iminosugar 5b. While,
hydrolysis of 1,2-acetonide followed by NaIO4 oxidative cleavage and hydrogenation using 10% Pd(OH)2/
C, H2 gave six membered 1-N-iminosugar 4a; the hydrogenation using 10% Pd/C–H2 however, gave N-
methyl substituted 1-N-iminosugar 4b. The hydrochloride salts of 4a/4b and 5b were found to be specific
Keywords:
1-N-iminosugars
Isofagomine analogues
Glycosidase inhibitors
a
-galactosidase and moderate
a
-glucosidae inhibitors, respectively, in micro molar range.
Ó 2011 Elsevier Ltd. All rights reserved.
D-Glucose
1. Introduction
D-Glucose
Ref. 1
Recently, we have reported a synthetic route1 to the five- and
six-membered aminocarbasugars I and II, respectively, using a
chiral synthon 1 which is obtained by the stereoselective Michael
NO2
H
6
O
O
H
O
Michael
O
EtO
EtO
5
Reaction
7
4
addition of nitromethane to
D-glucose derived a,b-unsaturated
3
O
O
1
CH3NO2
ester A followed by the intramolecular Henry reaction (after
hydrolysis of 1,2-acetonide) as key steps (Scheme 1). In the contin-
uation of our interest in iminosugars,2 we anticipated that the
Michael adduct 1 could be exploited for the preparation of new
analogues of six- and seven-membered 1-N-iminosugars.
BnO
BnO
2
O
O
A
1
Henry
Reaction
C6-C1
C6-C2
This class of compounds, also known as azasugars, are sugar
mimics in which the ring oxygen of monosaccharide is replaced
by the basic nitrogen atom.3 Nojirimycin (NJ) 2a ( Fig. 1) and
1-deoxynojirimycin (DNJ) 2b are the early studied examples of
iminosugars which were found to be potential inhibitors of carbo-
hydrate processing enzymes namely glycosidases and glycosyl
transferases.4 The study of iminosugars subsequently led to the
discovery of Migliol™ (N-hydroxyethyl DNJ) and Zavesca,™
(N-butyl DNJ) an iminosugar based drugs, commercialized for the
treatment of type II diabetes and Gaucher’s disease, respectively.5
In the search for more potent glycosidase inhibitors, a new class
of iminosugars wherein an anomeric carbon of sugar is replaced
by the basic nitrogen atom, known as 1-N-iminosugars (or 1-aza-
sugars),6 has emerged as potent and highly selective glycosidase
inhibitors. Bols and co-workers reported the first molecule of this
CH2OH
HOH2C
NH2
6
NH2
7
5
OH
OH
7
6
1
5
4
3
3
HO
OH
2
4
2
HO
OH
I
OH
II
Aminocarbasugars
Scheme 1. Synthesis of aminocarbasugars.
family and named as isofagomine 3a which was found to be selec-
tive inhibitor of b-glucosidase (Ki = 0.11
M, sweet almonds).6a
l
Due to the pronounced and selective inhibition activities of
1-N-iminosugars, several other analogues with variation in the ring
size along with position and the nature of hydroxy alkyl side chain
have been prepared. For example, Takahata and co-workers8a as
well as Mehta et al.8b reported the C5 hydroxyethyl side chain ana-
logues of 1-N-iminosugars known as homoisofagomine 3b and 3c,
⇑
Corresponding author. Tel.: +91 2025691727; fax: +91 2025691728.
E-mail address: ddd@chem.unipune.ac.in (D.D. Dhavale).
0968-0896/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2011.07.059

A. M. Jabgunde et al. / Bioorg. Med. Chem. 19 (2011) 5912–5915
5913
HO
NHCbz
O
R
OH
H
N
1
5
4
1
2
1
5
R
6
HO
HO
NH
NH
5
a
1
2
3
O
4
HO
HO
OH
3
4
HO
BnO
BnO
O
OH
6
OH
OH
2a R = OH (NJ)
2b R = H (DNJ)
3a R = OH (Isofagomine)
3b R = CH2OH
3c
b
NHCbz
OCHO
NHCbz
HO
HO
OH
d
HO
1
N
O
5
4
R
1
6
H
OH
R
NH
OH
NH
BnO
HO
2
HO
HO
5
O
OH
3
Y
e
X
4
OH
HO
HO
OH
c
4a R = H
or f
CH2OH
5a
5b
4b R = CH3
CH2OH
R
Figure 1. Iminosugars and 1-N-iminosugars.
N
N
HO
HO
5b R = H
HO
respectively. Recently, Vogel and co-workers have published the
conformationally more flexible one carbon ring homologue of isof-
agomine 5a which demonstrated potent inhibitory activity against
glycosidase and glucosylceramide transferase enzymes.9 The major
intricacy in constructing 1-N-iminosugars is the stereoselective
introduction of hydroxyalkyl group at the b-position of the ring
nitrogen. Despite this difficulty, a number of asymmetric as well
as chiron approaches to a variety of 1-N-iminosugars are reported
in the literature.7–10 We now report here synthesis of six- and se-
ven-membered 1-N-iminosugars with elongated hydroxyethyl side
chain at C5 4a/4b and 5b, respectively, and glycosidase inhibitory
activity of their hydrochloride salts.
OH
OH
4a R = H
4b R = Me
4c R = H.HCl
4d R = Me.HCl
g
g
5c R = H.HCl
Scheme 2. Reagents and conditions: (a) (i) LiAlH4, THF, 0 °C to reflux, 10 h; (ii) Cbz–
Cl, aq NaHCO3, MeOH, 4 h, 65%; (b) TFA–water (3:2), rt, 2 h; (c) H2, 10% Pd/(OH)2/C,
MeOH–H2O, 80 psi, rt, 36 h, 80%; (d) NaIO4, acetone–water, rt, 1 h; (e) H2, 10%
Pd(OH)2/C, MeOH–H2O, 80 psi, rt, 36 h, 75%; (f) H2, 10% Pd/C, dry MeOH, 80 psi, 40 h
59%; (g) HCl, MeOH, rt, 4 h.
dase (isolated from Geobacillus toebii BK1),
N-acetyl-b- -glucosaminidase (isolated from Jack bean seeds) and
-glucosidase (procured from Sigma Chemical Co). The IC50 and Ki
values obtained are summarised in Table 1. The isofagomine ana-
logues 4c and 4d were found to be specific competitive inhibitors
a-mannosidase and
2. Result and discussion
D
a
The requisite sugar appended
ration was prepared in high stereoselective manner from
c-nitroester 1 with
L
-ido-configu-
D
-glucose
in six steps as described earlier.1 In the subsequent step, one-pot
reduction of nitro and ester functionality in 1 using LAH in THF
at reflux followed by reaction with benzylchloroformate and NaH-
CO3 in methanol/water afforded N-Cbz protected aminol 6 in 65%
yield (Scheme 2).
of
a
-galactosidase with Ki = 66
l
M and Ki = 54
lM, respectively.
However, 4c and 4d showed weak inhibition against
a
-glucosidase
with 30% and 44% inhibition, respectively. On the other hand seven
membered iminosugar 5c was noticed to be moderate competitive
inhibitor of
IC50 values of 4c and 4d suggested 4d is more potent inhibitor of
-galactosidase under the assay condition. This may be attributed
a-glucosidase with Ki = 131 lM. Comparison of Ki and
In the next step, treatment of 6 with TFA–water (3:2) at room
temperature gave anomeric mixture of hemiacetal X (as evident
from the 1H NMR of the crude product) that was directly subjected
for the reductive aminocyclization under hydrogenation conditions
using catalytic 10% Pd(OH)2/C in methanol to afford seven
membered 1-N-iminosugar 5b in 80% yield. Treatment of 5b with
MeOH–HCl afforded hydrochloride salt 5c. While targeting the
synthesis of six membered 1-N-iminosugar 4a, the hemiacetal X
was treated with sodium metaperiodate in acetone–water to
furnish intermediate Y that on reaction with 10% Pd(OH)2/C in
methanol/water under hydrogen pressure afforded 5-epi-homoi-
sofagomine 4a in 75% yield. Reaction of 4a with MeOH–HCl gave
hydrochloride salt 4c. An interesting observation was noticed
when hydrogenation of Y was performed with 10% Pd/C in dry
methanol. After 40 h N-methylation of 5-epi-homoisofagomine
was observed to afford N-methyl-5-epi-homoisofagimine 4b as
the only product in 59% yield,11 that was converted to the hydro-
chloride salt 4d by treatment with MeOH–HCl.
a
to the N-alkylation of 4c.
Conclusion
We have demonstrated a short and an efficient methodology for
the synthesis of six- and seven-membered 1-N-iminosugars 4a, 4b,
and 5b and corresponding hydrochloride salts 4c, 4d, and 5c. Gly-
cosidase inhibitory activity study indicated that compounds 4c and
4d have higher inhibitory activity against
a-galactosidase, whereas
a-glucosidase was inhibited moderately by 5c. The increased po-
tency of alkyl derivative 4d towards
a-galactosidase encourage
further research on biological studies of modified alkyl amino
derivatives of 4d.
3. Experimental
2.1. Inhibitory activity evaluation
3.1. General methods
The glycosidase inhibitory activity of hydrochloride salt 4c, 4d
and 5c was evaluated against following glycosidases: b-galactosi-
dase and b-glucosidase (isolated from almond seeds), a-galactosi-
Melting points were recorded with Thomas Hoover melting
point apparatus and are uncorrected. IR spectra were recorded
with Shimadzu FTIR-8400 as a thin film or in nujol mull or using

5914
A. M. Jabgunde et al. / Bioorg. Med. Chem. 19 (2011) 5912–5915
Table 1
Inhibitory potencies of 4c, 4d and 5c
Enzymes
4c
4d
5c
a
a
a
IC50
(
lM)
Kib
(lM)
IC50
(lM)
Kib
(lM)
IC50
(lM)
Kib
(lM)
a
-Galactosidase (Geobacillus toebii BK 1)
b-Galactosidase (Almond Seeds)
-Glucosidase (Baker’s yeast)
b-Glucosidase (Almond Seeds)
-Mannosidases (Jack bean)
N-Acetyl-b- -glucosaminidase (Jack bean)
65
NI
NI
NI
NI
NI
66
NI
NI
NI
NI
NI
50
NI
NI
NI
NI
NI
54
NI
NI
NI
NI
NI
NI
NI
675
NI
NI
NI
NI
131
NI
NI
NI
a
a
D
NI
NI: no inhibition.
a
Less than 50% inhibition at 1 mM concentration of inhibitor.
No inhibition at 1 mM concentration of inhibitor. Data is average of three sets of assay performed.
b
KBr pellets and are expressed in cmꢀ1. 1H NMR (300 MHz) and 13
C
NCO2CH2Ph), 5.51 (1H, b t, J = 5.8 Hz, NHCO, exchangeable with
D2O), 5.90 (1H, d, J = 3.8 Hz, H-1), 7.20–7.42 (10H, m, Ar-H); 13C
NMR (CDCl3) 25.9 (CH3), 26.5 (CH3), 31.1 (C-6), 35.1 (C-5), 42.1
(CH2NH), 60.4 (C-7), 66.5 (OCH2Ph), 71.7 (NCO2CH2Ph), 81.1,
81.3, 83.0 (C-4/C-3/C-2), 104.5 (C-1), 111.3 (OCO), 127.7, 127.9
(strong), 128.0 (strong), 128.3, 128.4 (strong), 136.5, 136.9 (Ar),
157.1 (CO). Anal. Calcd. for C26H33NO7: C 66.22, H 7.05. Found C
66.15, H 6.99.
NMR (75 MHz) spectra were recorded with Varian Mercury instru-
ment using CDCl3 and/or D2O as solvent(s). Chemical shifts were
reported in d unit (parts per million) with reference to TMS as an
internal standard and J values are given in Hz. Elemental analysis
were carried out with Thermo-Electron Corporation CHNS analyzer
Flash-EA 1112 at Department of Chemistry, University of Pune,
Pune. Optical rotations were measured using JASCO P1020 digital
polarimeter with sodium light (589.3 nm) at 25 C. Thin-layer chro-
matography was performed on pre-coated plates (0.25 mm, Silica
gel 60 F254). Visualization was made by absorption of UV light
or by thermal development after spraying with 3.5% solution of
2,4-dinitrophenylhydrazine in ethanol/H2SO4 and with basic aque-
ous potassium permanganate solution. Column chromatography
was carried out with silica gel (100–200 mesh). Unless not mention
the reactions were carried out in an oven-dried glassware’s under
dry N2. Acetone, Methanol, DMF, and THF were purified and dried
before use. Distilled ethyl acetate, CH2Cl2, and methanol were used
for column chromatography. Petroleum ether that was used is a
distillation fraction between 40 and 60 °C. After decomposition of
the reaction with water, work-up involves washing of combined
organic layer with water, brine, drying over anhydrous sodium sul-
fate, and evaporation of solvent under reduced pressure.
3.1.2. 2(3R,4R,5R)-3, 4-Dihydroxy-5-(hydroxyethyl) piperidine
(4a) and its hydrochloride salt (4c)
Solution of 6 (0.4 g, 0.845 mmol) in TFA–H2O (4 mL, 3:2) was
stirred at 0 °C for 20 min and at room temperature for 2 h. TFA
was co-evaporated with toluene to furnish hemiacetal. To the stir-
red solution of hemiacetal in acetone–water (6 mL, 4:1) was added
NaIO4 (0.271 g, 1.268 mmol) at 0 °C. The resulting mixture was
stirred at 15 °C for 1 h. Acetone was removed on rotary evaporater
at 20 °C and product was extracted with dichloromethane CH2Cl2
(3 ꢁ 20 mL). The combined organic layer was concentrated, dried
(Na2SO4) and purified by silica gel column chromatography (ethyl
acetate/n-hexane = 1:1) to afforded viscous oil. The crude product
was dissolved in methanol/water (9:1) and hydrogenated at 80
psi using 10% Pd(OH)2/C at 30 °C for 36 h. The reaction mixture
was filtered through Celite, concentrated and purified using col-
umn chromatography (Methanol/Chloroform, 1:4) to afford 4a as
3.1.1. 13-O-Benzyl-5-(N-benzyloxyccarbonyl)-aminomethyl-5,6-
dideoxy-1,2-O-isopropylidine-b-
L-ido-hepto-1,4-furanose (6)
viscous oil (0.102 g, 75%) Rf 0.20 (1%, NH4OH/Methanol); ½a D22
ꢂ
To an ice-cold suspension of LAH (1.90 g, 50.07 mmol) in anhy-
drous THF (20 mL), a solution of 1 (4.1 g, 10.02 mmol) in THF
(15 mL) was added over 10 min. The resulting mixture was stirred
at room temperature for 15 min and then refluxed. After 10 h, the
reaction mixture was cooled to room temperature and quenched
with ethyl acetate (20 mL) followed by saturated solution of aq
ammonium chloride. The residue was filtered through Celite, sol-
vent was dried (Na2SO4) and concentrated to afford viscous oil.
To the above crude product in methanol–water (9:1) was added
sodium bicarbonate (2.25 g, 30.0 mmol) and benzylchloroformate
(50% solution in toluene) (5.1 mL, 15.0 mmol) at 0 °C. The resulting
mixture was stirred at room temperature for 4 h. Methanol was re-
moved on rotary evaporator under reduced pressure and the prod-
uct was extracted with EtOAc (3 ꢁ 40 mL). The combined organic
layer was dried (Na2SO4) and concentrated. Column purification
of crude product using pet ether/ethyl acetate = 4:1 gave 6 as a vis-
15.5 (c 0.18, MeOH); IR: 3600–2900 (broad) cmꢀ1 1H NMR
;
(D2O): d 1.48–1.61 (m, 1H, H-6), 1.62–1.78 (1H, m, H-6), 2.28–
2.42 (1H, m, H-4a), 2.93 (1H, t, J = 12.3 Hz, H-5a), 3.08–3.36 (3H,
m, H-1a, H-1e, H-5e), 3.67 (2H, t, J = 6.6 Hz, H-7), 3.87 (1H, br s,
H-3), 4.03 (1H, br s, H-2); 13C NMR (D2O): d 29.9 (C-6), 30.2 (C-
4), 43.1, 44.5 (C-1/C-5), 58.6 (C-7), 65.9 (C-2), 67.4 (C-3). Anal.
calcd. for C7H15NO3: C 52.16, H 9.38; Found C 52.20, H 9.31. Solu-
tion of 4a (0.04 g, 0.248 mmol) in methanol/HCl (2 mL, 0.5 M) was
stirred at 25 °C for 4 h. The solvent was evaporated under reduced
pressure and the residue was washed with ethyl acetate, dry ether
and dried under vacuum to get 4c (0.04 g, 81% yield) as a semisolid.
Rf 0.12 (1%, NH4OH/methanol) (elongated tail observed on TLC
plate); ½a 2D3
ꢂ
ꢀ5.4 (c 0.2, MeOH); IR: 3600–2900 (broad) cmꢀ1
;
1H
NMR (300 MHz, D2O); d 1.48–1.62 (1H, m, H-6), 1.62–1.78 (1H,
m, H-6), 2.28–2.44 (1H, m, H-4a), 2.95 (1H, t, J = 12.3 Hz, H-5a),
3.12–3.38 (3H, m, H-1a, H-1e, H-5e), 3.67 (2H, t, J = 6.6 Hz, H-7),
3.88 (1H, br s, H-3), 4.04 (1H, br s, H-2); 13C NMR (D2O): d 29.3
(C-6), 30.3 (C-4), 42.7, 44.5 (C-1/C-5), 58.5 (C-7), 65.5 (C-2), 66.5
(C-3). Anal. calcd. for C7H16ClNO3: C 42.54, H 8.16; Found C
42.39, H 8.02.
cous oil (3.07 g, 65%). Rf 0.42 (ethyl acetate/pet ether = 1:4); ½a D25
ꢂ
ꢀ35.4 (c 4.8, CHCl3); IR (neat): 3650–3200 (broad), 2982, 1712,
1518, 1255, 1074, 1024 cmꢀ1 1H NMR (CDCl3) d 1.22–1.44 (5H,
;
m, CH3, H-6), 1.48 (3H, s, CH3), 2.12–2.25 (1H, m, H-5), 2.45 (1H,
br s, –OH, exchangeable with D2O), 3.30 (1H, dt, J = 11.8 and
5.9 Hz, CH2NH), 3.46–3.59 (1H, m, CH2NH), 3.62–3.78 (2H, m, H-
7), 3.87 (1H, d, J = 3.0 Hz, H-3), 3.95 (1H, dd, J = 10.0 and 3.0 Hz,
H-4), 4.45 (1H, d, J = 11.7 Hz, OCH2Ph), 4.62 (1H, d, J = 3.8 Hz, H-
2), 4.69 (1H, d, J = 11.7 Hz, OCH2Ph), 5.07 (2H, ABq, J = 12.3 Hz,
3.1.3. 31,5,6-Trideoxy-5-hydroxyethyl-1-6-imino-(2S,3R,4R,5R)-
D-glucitol (5b) and its hydrochloride salt (5c)
Reaction of 6 (0.198 g, 0.421 mmol) with TFA–H2O (3 mL, 3:2)
at 0 °C gave hemiacetal as a viscous oil. That on hydrogenation in

A. M. Jabgunde et al. / Bioorg. Med. Chem. 19 (2011) 5912–5915
5915
methanol using 10% Pd(OH)2/C (0.060 g) at 80 psi using at 30 °C for
36 h. Work up of reaction afforded 5b as viscous oil (0.064 g, 80%).
and absorbance of the liberated p-nitrophenol was measured at
405 nm with a UV–visible Spectrophotometer. Controls were run
simultaneously in the absence of test compound. One unit of glyco-
sidase activity is defined as the amount of enzyme that hydrolyzed
Rf 0.15 (1%, NH4OH /Methanol); ½a D27
ꢀ3.3593 (c 0.16, MeOH); IR
ꢂ
(neat): 3650–2900 (broad) cmꢀ1 1H NMR (D2O) d 1.52–1.84 (2H,
;
m, H-7), 2.17–2.32 (1H, m, H-5), 2.89 (1H, dd, J = 13.6 3.9 Hz, H-
1a) 3.02–3.28 (3H, m, H-1e, H-6), 3.69 (2H, t, J = 6.6 Hz, H-8),
3.82–4.02 (3H, m, H-2, H-3, H-4); 13C NMR (D2O) d 33.1 (C-7),
33.7 (C-5), 45.9, 47.5 (C-1/C-6), 59.5 (C-8), 72.1, 75.1, 76.3 (C-2)/
(C-3)/(C-4). Reaction of compound 5b (0.043 g, 0.225 mmol) with
methanol–HCl (2 mL, 0.5 M) gave hydrochloride salt (following
the same procedure as 4c) as semisolid 5c (0.047 g, 93% yield): Rf
1 lmol of p-nitrophenol per minute under assay condition. The
inhibition constants (Ki) and the nature of the inhibition were
determined from Lineweaver Burk plots.
Acknowledgments
We are thankful to the CSIR (Project No. 01(2343)/09/EMR-II),
New Delhi, for financial support. A.M.J. is thankful to the UGC
(New Delhi). N.B.K. and S.T.C. are thankful to the CSIR (New Delhi)
for Senior Research Fellowships.
0.11 (1% NH4OH/methanol); ½a D22
ꢀ16.5 (c 0.3, MeOH); IR (neat):
ꢂ
3650–2900 (broad) cmꢀ1 1H NMR (D2O) d 1.60–1.82 (2H, m, H-
;
7), 2.36–2.49 (1H, m, H-5), 3.21 (1H, dd, J = 13.2, 4.7 Hz, H-6)
3.25–3.48 (3H, m, H-1a, H-1e, H-6), 3.68 (2H, t, J = 6.5 Hz, H-8),
3.94–4.04 (2H, narrow m, H-3, H-4), 4.40–4.53 (1H, m, H-2); 13C
NMR (D2O) d 30.2 (C-7), 33.1 (C-5), 44.9, 45.0 (C-1/C-6), 58.9 (C-
8), 69.8, 73.9, 74.2 (C-2)/(C-3)/(C-4).
Supplementary data
Supplementary data (general experimental methods. 1H and 13
NMR spectra of compounds 6, 4a, 4c, 4d, 5b, and 5c. Lineweaver–
Burk plot of 4c, 4d, with -galactosidase and 5c with -glucosi-
C
a
a
3.1.4. 4(3R,4R,5R)-3,4-Dihydroxy-5-(hydroxyethyl)-N-methyl-
piperidine (4b) and its hydrochloride salt (4d)
dase) associated with this article can be found, in the online ver-
sion, at doi:10.1016/j.bmc.2011.07.059.
Reaction of 6 (0.164 g, 0.348 mmol) with TFA–H2O (3 mL, 3:2)
followed by treatment with NaIO4 (0.112 g, 0.522 mmol). Follow-
ing the same reaction procedure as in 4a, afforded intermediate
Y. That on hydrogenation in dry methanol at 80 psi using 10%
Pd-C (0.050 g) at 30 °C for 40 h and work up afforded 4b as a vis-
cous oil (0.036 g, 59%). Treatment of 4b (0.036 g, 0.205 mmol) with
methanol–HCl (2 mL, 0.5 M) as in case of 4a, afforded hydrochlo-
ride salt 4d (0.038 g, 89% yield) as a semisolid. Rf 0.22 (1%, NH4OH
References and notes
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Kumar, K. S.; Chaudhari, V. D.; Sharma, T.; Sabharwal, S. G.; Reddy, P. J. Org.
Biomol. Chem. 2005, 3, 3720; (e) Sanap, S. P.; Ghosh, S.; Jabgunde, A. M.; Pinjari,
R. V.; Gejji, S. P.; Singh, S.; Chopade, B. A.; Dhavale, D. D. Org. Biomol. Chem.
2010, 8, 3307; (f) Mane, R. S.; Ajish Kumar, K. S.; Dilip, D. D. J. Org. Chem. 2008,
73, 3284; (g) Bande, O. P.; Jadhav, V. H.; Puranik, V. G.; Dhavale, D. D.
Tetrahedron: Asymmetry 2007, 18, 1176. and references cited therein.
3. Iminosugars: From Synthesis to Therapeutic Applications; Compain, P., Martin,
O. R., Eds.; John Wiley: Chichester, UK, 2007; For recent reviews on iminosugars
see (b) De Melo, E. B.; Gomes, A. S.; Carvalho, I. Tetrahedron 2006, 62, 10277; (c)
Lillelund, V. H.; Jensen, H. H.; Liang, X.; Bols, M. Chem. Rev. 2002, 102, 515.
4. Stutz, A. E. Iminosugars as Glycosidase: Inhibitors Nojirimycin and Beyond, first
ed.; Wiley: Weinheim, Germany, 1999.
/methanol) (elongated tail observed on TLC plate); ½a D22
ꢂ
6.5 (c 1,
MeOH); IR (neat): 3650–2900 (broad) cmꢀ1 1H NMR (D2O): d
;
1.47–1.62 (1H, m, H-6), 1.63–1.78 (1H, m, H-6), 2.36–2.48 (1H,
m, H-4a), 2.86 (3H, s, NCH3), 2.96 (1H, t, J = 12.6 Hz, H-5a), 3.25
(1H, dd, J = 12.6, 3.9 Hz, H-5e), 3.32 (2H, br s, H-1a, H-1e, accidental
equivalence), 3.68 (2H, t, J = 6.5 Hz, H-7), 3.85 (1H, apparent triplet,
J = 2.7 Hz, H-5a), 4.03–4.12 (1H, narrow multiplet, J = 1.7 Hz, H-2e);
13C NMR (D2O): d 29.9, 30.1 (C-6)/(C-4), 43.2 (NCH3), 53.1 (C-5)
54.1 (C-1), 58.2 (C-7), 65.2 (C-2), 66.2 (C-3). Anal. calcd. for
C8H18ClNO3: C 45.39, H 8.57, Found C 45.36, H 8.62.
5. (a) Cox, T.; Lachmann, R.; Hollak, C.; Aerts, J.; van Weely, S.; Hrebicek, M.; Platt,
F. M.; Butters, T. D.; Dwek, R.; Moyses, C.; Gow, I.; Elstein, D.; Zimran, A. Lancet
2000, 355, 1481; (b) Johnston, P.; Feig, P.; Coniff, R.; Krol, A.; Kelley, D.;
Mooradian, A. Diabetes Care 1998, 21, 416.
3.2. General procedure for inhibition assay
6. (a) Jespersen, T. M.; Dong, W.; Sierks, M. R.; Skrydstrup, T.; Lundt, I.; Bols, M.
Angew. Chem., Int. Ed. Engl. 1994, 33, 1778; (b) Jespersen, T. M.; Bols, M.; Sierks,
M. R.; Skrydstrup, T. Tetrahedron 1994, 50, 13449.
7. Liu, H.; Liang, X.; Søhoel, H.; Bulow, A.; Bols, M. J. Am. Chem. Soc. 2001, 123,
5116.
8. (a) Ouchi, H.; Mihara, Y.; Takahata, H. J. Org. Chem. 2005, 70, 5207; (b) Mehta,
G.; Mohal, N. Tetrahedron Lett. 2000, 41, 5747; (c) Ouchi, H.; Mihara, Y.;
Watanabe, H.; Takahata, H. Tetrahedron Lett. 2004, 45, 7053.
The substrates p-nitrophenyl-
nyl-b- -glucopyranoside, p-nitrophenyl-
p-nitrophenyl-b- -galactopyranoside, p-nitrophenyl-N-acetyl-b-
glucopyranoside and p-nitrophenyl- -mannopyranoside were
procured from Sigma Chemicals Co., USA.
a
-
D
-glucopyranoside, p-nitrophe-
D
a-D
-galactopyranoside,
D
D-
a-D
Inhibition activities of 5-epi-homoisofagomine hydrochloride
4c, N-methyl-5-epi-homoisofagomine hydrochloride 4d and tri-
hydroxyazepane hydrochloride 5c were determined by measuring
the residual hydrolytic activities of the glycosidases with 2 mM
concentration of p-nitrophenyl-glycopyranoside prepared in cit-
rate buffer (0.025 M, pH 4.0) and used for assay. The test com-
9. (a) Li, H.; Liu, T.; Zhang, Y.; Favre, S.; Bello, C.; Vogel, P.; Butters, T. D.;
Oikonomakos, N. G.; Marrot, J.; Bleriot, Y. ChemBioChem 2008, 9, 253; (b) Li, H.;
Zhang, Y.; Vogel, P.; Sinay, P.; Bleriot, Y. Chem. Commun. 2007, 183; (c) Mehta,
G.; Lakshminath, S. Tetrahedron Lett. 2002, 43, 331.
10. (a) Ichikawa, Y.; Igarashi, Y.; Ichikawa, M.; Suhara, Y. J. Am. Chem. Soc. 1998,
120, 3007; (b) Kim, Y. J.; Ichikawa, M.; Ichikawa, Y. J. Org. Chem. 2000, 65, 2599;
(c) Pandey, G.; Kapur, M. Tetrahedron Lett. 2000, 41, 8821; (d) Pandey, G.;
Kapur, M. Org. Lett. 2002, 4, 3883; (e) Pandey, G.; Dumbre, S. G.; Khan, M. I.;
Shabab, M. J. Org. Chem. 2006, 71, 8481; (f) Gupta, P.; Dharuman, S.; Vankar, Y.
D. Tetrahedron: Asymmetry 2010, 21, 2966. and references cited therein.
11. In 13C NMR spectrum of compound 4d along with N–CH3 signal at d 45.8 Hz,
the C2 and C6 (–N–CH2) appeared at d 56.7 and 55.6 Hz as a downfield signals
compared to the corresponding piperidine 4c. This is due to the b-substituent
(N-substitution) effect.
pound (of various concentrations from 10
pre-incubated with the enzyme, buffered at its optimal pH, for
1 h at 37 °C (for -galactosidase at 60 °C). The enzyme reaction
was initiated by the addition of 100 L of substrate. Reaction was
terminated with the addition of 0.05 M borate buffer (pH 9.8)
lM to 1000 lM) was
a
l