Spirocyclopropyl pyrrolidines as a new series of α-l-fucosidase inhibitors

Article abstract of DOI:10.1016/j.bmc.2006.02.005

Polyhydroxy 4-azaspiro[2.4]heptane derivatives (spirocyclopropyl iminosugars) were prepared in four to six steps from readily available protected aldoses. The key step of the reaction sequence involves a titanium-mediated aminocyclopropanation of glyconon

Full text of DOI:10.1016/j.bmc.2006.02.005

Bioorganic & Medicinal Chemistry 14 (2006) 4047–4054
Spirocyclopropyl pyrrolidines as a new series
of a-L-fucosidase inhibitors
Christophe Laroche,a Jean-Bernard Behr,a,* Jan Szymoniak,a Philippe Bertus,a
Catherine Schutz,b Pierre Vogelb and Richard Plantier-Royona,*
¨
aLaboratoire ‘Re´actions Se´lectives et Applications,’ Universite´ de Reims Champagne-Ardenne, UMR URCA/CNRS 6519,
UFR Sciences, BP 1039, F-51687 Reims Cedex 2, France
b
`
´
Laboratoire de Glycochimie et Synthese Asymetrique, Ecole Polytechnique Federale de Lausanne (EPFL),
´ ´
BCH CH-1015 Lausanne, Switzerland
Received 14 December 2005; revised 24 January 2006; accepted 3 February 2006
Available online 20 February 2006
Abstract—Polyhydroxy 4-azaspiro[2.4]heptane derivatives (spirocyclopropyl iminosugars) were prepared in four to six steps from
readily available protected aldoses. The key step of the reaction sequence involves a titanium-mediated aminocyclopropanation
of glycononitriles with subsequent cyclization. Five new polyhydroxypyrrolidines so-obtained have been evaluated for their ability
to inhibit 16 glycosidases. One of them exhibits selective inhibition of a-L-fucosidase from bovine kidney (Ki = 1.6 lM, competitive).
ꢀ 2006 Elsevier Ltd. All rights reserved.
1. Introduction
dase inhibitors. Nitrogen-containing fucose analogues
such as 1,5-dideoxy-1,5-iminoalditols like deoxyfuconoj-
irimycin 1, or 1,4-dideoxy-1,4-iminoalditols 2–11 were
shown to interfere with the fucose-processing enzymes
(Fig. 1). It is usually postulated that these iminosugars
compete with the natural substrate (a fucose glycoside
or fucose-GDP) by mimicking its charge distribution
and hydroxyl group topography at the transition state
of the biocatalytic reaction.15–17 Thus, deoxyfuconojiri-
mycin 1 is the most potent inhibitor of a-L-fucosidase
known so far (Ki = 5 nM).18
Fucosyltransferases and a-L-fucosidases are involved in
the processing of fucosylated glycoconjugates.1–3 Owing
to the great variety of physiological and pathological
events relevant to fucose-containing oligosaccharides,4–6
increasing attention has been drawn to the mode of ac-
tion and inhibition of these enzymes. For instance, hu-
man a-1,3-fucosyltransferase, responsible for the
production of sialyl Lex,7,8 is a potential target for the
development of antiinflammatory agents.9 On the other
hand, high activity and aberrant distribution of a-fuco-
sidases have been observed in cancer cells.10,11 Conse-
quently, fucosidases have been recognized as diagnostic
markers for the early detection of colorectal and hepato-
cellular cancers. Moreover, a-fucosidase inhibitors have
also been found to reduce HIV-infection, certainly by
altering the glycosylation pattern of viral glycoproteins
responsible for host cell surface binding.12–14
The five-membered-ring iminosugars featuring a methyl
group at C-5 also displayed potent fucosidase inhibition
properties (Ki = 8 nM for 4 and Ki = 10 nM for 2; Ki in
the micromolar range for other structures). A variety of
configurations have been encountered in the pyrrolidine
series (Fig. 1).19–23 Moreover, Wong et al. have reported
a synergistic inhibition of fucosyltransferase by imino-
sugar 7 in combination with GDP.24 Other iminosugar-
based fucosyltransferase inhibitors have been described
since then.25,26 Finally, the protected iminosugar 11 dis-
played a pronounced anti-HIV activity (50% reduction
of virus yield in infected cells at 20 lM).13
Much effort has been devoted towards the synthesis and
biological evaluation of fucosyltransferase and fucosi-
Keywords: Azasugars; Glycosidases; Inhibition; Spiro compounds.
*
Corresponding authors. Tel.: +33 326 91 32 38; fax: +33 326 91 31 66
(J.-B.B.); tel.: +33 326 91 33 08; fax: +33 326 91 31 66 (R.P.R.);
e-mail addresses: jb.behr@univ-reims.fr; richard.plantier-royon@
univ-reims.fr
We have recently explored the aminocyclopropanation
of protected carbohydrates,27 with the aim of synthesiz-
ing new cyclopropane-containing sugar analogues.28
0968-0896/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.bmc.2006.02.005

4048
C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
CH
CH
CH
3
3
3
CH
3
HO
HO
HO
HO
HO
HO
HO
HO
NH
O
NH
NH
OH
R
2
R
1
OH
R
OH
1
22a
19
1
6a: R =CH OH, R =H, K =83 μM
L-Fucose
2: R =OH, K =0.01 μM
1
2
2
i
1
i
18
22b
20
DFJ, K=0.005 μM
6b: R =H, R =CH OH, K =9 μM
i
L-3: R =CH OH, K =1.4 μM
4: R =CH CH OH, K =0.008 μM
1
2
2
i
1
2
i
19
1
2
2
i
21
N
5: R =
K =0.08 μM
1
i
N
CH
CH
3
CH
CH
3
3
3
HO
HO
HO
HO
HO
HO
O
NH
NH
O
NH
R
NH
R
2
2
OH
R
OH
R
1
1
20
20
23
23
(+)-11: anti-HIV activity,
7: R =CH OH, R =H, K =4 μM
L-9: K =8 μM
10: R =CH OH, R =H, K =44 μM
1
2
2
i
i
1
2
2
i
–
13
23
D-9:
EC =20μM
(structure not shown)
8: R =H, R =CH OH, K =165 μM
D-3: R =H, R =CH OH, K =11 μM
50
1
2
2
i
1
2
2
i
23
K =0.5 μM
i
Figure 1. Structures of compounds 1–11 and their inhibitory activities on a-L-fucosidase from bovine kidney.
materials for the synthesis of the targeted spirocyclopro-
pyl iminosugars 12a–e. As described in Scheme 1, the
reaction of the commercially available D-mannose deriv-
ative 13a with hydroxylamine hydrochloride in the pres-
ence of a base (NaHCO3) afforded the corresponding
aldoxime, which in turn was treated with an excess of
methanesulfonyl chloride in pyridine. Dehydration oc-
curred together with the mesylation of the C-5 free
hydroxyl group to afford the nitrile 14a30 in acceptable
yield (49%). Cyclopropanation of 14a required the ini-
tial formation of the reactive organometallic species,
resulting from the reaction of EtMgBr (2 equiv) with
Ti(O-iPr)4. Under these conditions, a titanacyclopro-
pane generated in situ reacted with the nitrile to form
the corresponding cyclopropylamine.29 The mechanism
of this multistep transformation has been postulated in
a previous communication29a and might be related to
HO
HO
HO
HO
NH
H
NH
R
2
R
1
HO
OH
12a
12b: R =CH OH, R =H
12c: R =H, R =CH OH
1
2
2
1
2
2
HO
HO
HO
HO
NH
OH
NH
OH
12d
12e
Figure 2. Structures of iminosugars 12a–e.
The replacement of the C-5 methyl group in structures
like 2–11 by a spirocyclopropane ring could induce elec-
tronic and conformational modifications and conse-
quently enhance the binding interactions towards the
biological receptor. Accordingly, we describe herein
the synthesis as well as the biological evaluation on a-
L-fucosidase and other glycosidases of a series of spiro-
cyclopropyliminosugars 12a–e (Fig. 2).
O
O
H
OMs
O
N
OH
O
O
i, ii
49%
O
O
O
O
2. Results and discussion
2.1. Chemistry
14a
iii
38%
13a
H
Titanium-mediated aminocyclopropanation of nitriles is
a very convenient reaction that has been studied in our
laboratories for several years.29 Though highly reactive
entities are involved in the process, we recently applied
this transformation to functionalized substrates such
as protected carbohydrates.27 Our first trials to synthe-
size a spirocyclopropyl iminosugar based on this chem-
ical transformation have also been reported in a
previous communication.28
O H
N
OMs
O
O
NH
2
O
O
O
O
O
15a
12a
iv
91%
Scheme 1. Synthesis of compound 12a. Reagents and conditions: (i)
NH2OHÆHCl, NaHCO3, EtOH/H2O; (ii) MsCl, pyridine; (iii) EtMgBr
(2.2 equiv), Ti(OiPr)4, ꢀ78 ꢁC to rt, then BF3ÆOEt2 (2 equiv), then
H2O; (iv) 1 M HCl, rt, then Dowex 50 W-X8.
Since nitriles can easily be obtained from aldehydes, we
envisioned the fully protected aldoses 13a–e as starting

C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
4049
the analogous Kulinkovitch and De Meijere reactions.31
Titanium tetraisopropoxide (1 equiv) and EtMgBr
(2 equiv) were added to an ethereal solution of 14a at
ꢀ78 ꢁC and the resulting yellow solution was slowly
warmed up to 0 ꢁC. The addition of BF3ÆOEt2 was re-
quired at this stage of the reaction to afford the targeted
cyclopropylamine. As expected, cyclization occurred
in situ, arising from the intramolecular nucleophilic dis-
placement of the mesylate by the cyclopropylamine moi-
ety. Protected azasugar 15a was isolated in pure form in
38% yield, after neutralization of the reaction mixture
and purification by column chromatography. Standard
deprotection of the isopropylidene and subsequent puri-
fication by ion-exchange chromatography (Dowex
50WX-8, elution with 0.8 M NH4OH) afforded azasugar
12a as a white solid. According to previous observa-
tions,28 the ring closure was assumed to occur with
inversion of the configuration at the C-4 stereocenter
of the D-mannose starting compound. Thus, azasugar
12a might be regarded as an analogue of the potent
a-L-fucosidase inhibitor 4 with a supplementary hydrox-
yl group on the side arm and a spiro cyclopropyl group
in place of the L-configured methyl substituent. Other L-
fucosidase inhibitors have been prepared following a
related approach using also diacetonide D-mannose
13a.21
(70–80% overall yield). The cyclopropanation/cycliza-
tion procedure was conducted in the presence of
Ti(O-iPr)4/2 EtMgBr and BF3ÆOEt2, which afforded the
benzyl-protected azasugars 15b–e (38–45% yield). The
structures of the so-formed pyrrolidines were confirmed
by HRMS and NMR experiments. In particular, the rel-
atively high-field chemical shift of the C-5 methine car-
bon atoms at dC 58–64 indicated that they must be
bonded to nitrogen (the 13C NMR chemical shifts of
the corresponding carbon atoms in furanoses 13b–e
are dC 75–80). The final step involved exhaustive deben-
zylation of pyrrolidines 15b–e. This is usually a difficult
task since the presence of nitrogen is known to inhibit
the hydrogenolysis of O-benzyl-protecting groups. The
introduction of HCl or AcOH in the reaction mixture
as well as the use of black Pd or ammonium formate
for hydrogen transfer allowed to overcome these draw-
backs. However, the cyclopropyl group might also be
transformed under these harsh reaction conditions. Nev-
ertheless, debenzylation of 15b–e was smoothly achieved
after N-Boc protection of the cyclic secondary amine.
Subsequent acidic removal of the urethane moiety fol-
lowed by ion-exchange chromatography provided the
targeted iminosugars 12b–e. The process, as a whole,
was successful and purification was not required in each
individual step. Azasugars 12b–e were isolated as very
hygroscopic yellow solids and their structures were con-
firmed by spectral and analytical data.
The syntheses of spirocyclopropyl azasugars 12b–e were
performed by an analogous procedure, starting from
2,3,5-tri-O-benzylated furanoses 13b–e (Scheme 2). Tri-
O-benzyl-D-arabinose 13b and its enantiomer 13d are
commercially available. Protected L-xylose 13c32 and
D-ribose 13e33 were prepared according to previously
published procedures via their methylglycofuranosides.
Conversion to the corresponding glycononitriles 14b–e
was performed in two steps as above, by the reaction
with hydroxylamine and the dehydration/mesylation
process with an excess of methanesulfonyl chloride
2.2. Glycosidase-inhibition assays
Spirocyclopropyl azasugars 12a–e have been evaluated
for their inhibitory activities towards a-L-fucosidase
from bovine kidney as well as fifteen other commercial-
ly available glycosidases (Table 1). Apart from a very
weak inhibition (9% and 16%, respectively) towards
b-galactosidases from bovine liver and Aspergillus ori-
zae, pyrrolidine 12a was a potent and selective inhibitor
of a-L-fucosidase (96%). Kinetic analysis revealed a
competitive inhibition pattern, with Ki = 1.6 lM.
Azasugar 12a did not inhibit the other glycosidases at
the maximum tested concentration of 1 mM: coffee
beans and Escherichia coli a-galactosidase, E. coli b-ga-
lactosidase, yeast and rice a-glucosidases, Aspergillus ni-
ger and rhizopus mold amyloglucosidases, almonds
b-glucosidase, and jack beans a-mannosidase, Helix
pomatia b-mannosidase, A. niger b-xylosidase, jack
beans and bovine kidney b-N-acetyl-glucosaminidase.
OMs
R
R
O
R
6
6
N
i, ii
OH
R
5
5
70-80%
R
R
R
1
R
4
4
1
R
R
R
2
R
2
3
3
14b-e
iii
40-45%
13b-e
H
N
R
R
The four stereoisomers 12b–e are much weaker inhibi-
tors of a-L-fucosidase than analogue 12a but, despite
their marked differences in their absolute configurations,
12b–e display very similar affinities towards this enzyme
(41–55% inhibition at 1 mM). They also inhibit b-galac-
tosidase from bovine liver (24–73%) to a larger extent
than 12a. Surprisingly, the D-arabino configurated aza-
sugar 12c is a moderate inhibitor of amyloglucosidases
from A. niger (IC50 = 100 lM) and rhizopus mold
(IC50 = 47 lM) but is completely inactive towards other
a-glucosidases. This behaviour is very similar to that ob-
served for polyhydroxylated pyrrolizidines like casuar-
ine or analogues.34 Stereoisomers 12d,e are weak
inhibitors of rice a-glucosidase (11% and 45%,
5
iv,v,vi
6
12b-e
R
2
1
R
38-44%
4
R
R
3
15b-e
b : R =R =R =H,R =R =OBn, R =CH OBn
c : R =R =R =H,R =R =OBn, R =CH OBn
d : R =R =R =H,R =R =OBn, R =CH OBn
e : R =R =R =H,R =R =OBn, R =CH OBn
1
4
5
2
3
6
2
1
4
6
2
3
5
2
2
3
6
1
4
5
2
2
4
5
1
3
6
2
Scheme 2. Synthesis of stereoisomers 12b–e. Reagents and conditions:
(i) NH2OHÆHCl, NaHCO3, EtOH/H2O; (ii) MsCl, pyridine; (iii)
EtMgBr (2.2 equiv), Ti(O-iPr)4, ꢀ78 ꢁC to rt, then BF3ÆOEt2 (2 equiv),
then H2O; (iv) Boc2O (2 equiv), NEt3, THF; (v) H2, Pd/C, MeOH, rt;
(vi) 1 M HCl, rt, then Dowex 50 W-X8.

4050
C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
Table 1. Inhibition data of compounds 12a–e towards a-L-fucosidase from bovine kidney
Enzyme
12a
12b
12c
12d
12e
a-L-Fucosidase
Bovine kidney
97% IC50 = 13 lM Ki = 1.6 lMa
49%
50%
41%
55%
b-Galactosidase
Bovine liver
Aspergillus orizae
9%
16%
24%
b
—
73%
—
65%
—
49%
—
a-Glucosidase
Rice
—
—
—
11%
45%
Amyloglucosidase
Aspergillus Niger
Rhizopus mold
—
—
—
—
82%(IC50 = 100 lM)
84%(IC50 = 47 lM)
—
—
—
—
b-Glucosidase
Almonds
—
—
—
—
30%
Inhibition values are expressed as % of inhibition at 1 mM concentration.
a Competitive.
b No inhibition detected at 1 mM.
respectively), whereas 12b had no effect on a-glucosidas-
es. In addition, a 30% inhibition of b-glucosidase from
almonds was observed for compound 12e. Stereoisomers
12b–e did not inhibit the other glycosidases at 1 mM.
have a methyl group instead of the cyclopropyl group, it
is an attractive lead according to the observed enzyme
selectivity. Furthermore, the more pronounced hydro-
phobic character of the spirocyclopropyl iminosugars
makes them valuable models for their biological evalua-
tion as anti-HIV or anti-cancer agents.
In contrast to 1-deoxyfuconojirimycin 1, the structural
analogues or epimers of which showed reduced inhibitory
activities towards a-L-fucosidase, a variety of configura-
tions are tolerated for polyhydroxypyrrolidines (Fig. 1).
This phenomenon has been attributed to the sterically
less demanding character of the five-membered half-
chair-like inhibitors when compared to six-membered
chair-like azasugars. Accordingly, polyhydroxypyrroli-
dines from either the L-series (compounds 2–5, L-9) or
the D-series (6–8, D-9 and 10) exhibit fucosidase inhibi-
tion in the micromolar range. Nevertheless, the most ac-
tive isomers possess the all-cis orientation of the
substituents at positions 3, 4, and 5. Our results are in
agreement with this latter observation, since 12a is the
most potent inhibitor among the tested spirocyclopropyl
iminosugars. The presence of a spirocyclopropyl substi-
tuent, which could mimic the methyl group in either the
L- or D-series, seems detrimental for binding to fucosi-
dase. This is particularly obvious when comparing the
kinetic values of epimers 8 and L-9 with their cyclopro-
pyl-bearing analogue 12c. This result could be attributed
either to disfavourable interactions in the binding site or
to the inadequate conformation of the pyrrolidine ring
induced by the spirocyclopropyl substituent. The synthe-
sis and biological evaluation of a gem-dimethyl analogue
might permit us to answer this question.
4. Experimental
4.1. Chemistry
4.1.1. General information. 2,3:5,6-Di-O-isopropylidene-
a-D-mannofuranose was purchased from Acros. 2,3,5-
Tri-O-benzyl-b-L-arabinofuranose and 2,3,5-tri-O-ben-
zyl-b-D-arabinofuranose were obtained from Sigma.
All reactions were performed under argon. Diethyl ether
was distilled from sodium/benzophenone ketyl before
use. Ti(O-iPr)4 was used as received. Grignard reagents
were titrated in THF by menthol in the presence of
orthophenanthroline. Merck silica gel F254 (0.2 mm)
was used for TLC plates, detection being carried out
by spraying with an alcoholic solution of phosphomo-
lybdic acid or an aqueous solution of KMnO4 (2%)/
Na2CO3 (4%), followed by heating. Flash column chro-
matography was performed over silica gel Merck 9385
(40–63 lm) Kieselgel 60. NMR spectra were recorded
1
on a Bruker AC 250 spectrometer (250 MHz for H,
62.5 MHz for 13C). Chemical shifts are expressed in
parts per million using TMS as internal standard. Cou-
pling constants are in hertz and splitting pattern abbre-
viations are: br, broad; s, singlet; d, doublet; t, triplet; q,
quartet; m, multiplet. Optical rotations were determined
with a Perkin-Elmer Model 241 polarimeter in the spec-
ified solvents. High-resolution mass spectra (HRMS)
were performed on Q-TOF Micro micromass positive
ESI (CV = 30 V).
3. Conclusion
Efficient syntheses of new iminosugars containing spiro-
cyclopropyl groups are disclosed. One of them,
(5S,6R,7S)-6,7-dihydroxy-5-[(1S)-1,2-dihydroxyethyl]-
4-azaspiro[2.4]heptane 12a, which shares with L-fucose
the same configuration at C-2, C-3, C-4, exhibits potent
inhibition of a-L-fucosidase from bovine kidney
(Ki = 1.6 lM, competitive). Though 12a is a weaker
a-L-fucosidase inhibitor than analogues 2, L-3 or 4 that
4.1.2. Representative procedure for the preparation of
glycononitriles: 2,3,5-Tri-O-benzyl-4-O-methanesulfonyl-
D-arabinononitrile (14b). To a stirred solution of NH2O-
HÆHCl (6.40 g, 92 mmol) in EtOH (70 mL) and H2O
(70 mL) was added NaHCO3 (6.70 g, 80 mmol) by small

C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
4051
portions. After 15 min at rt, the protected aldose 13b
(8.40 g, 20 mmol) was slowly added and the resulting
mixture was reacted for 2 h at rt. The mixture was
extracted with Et2O (3· 50 mL), dried (MgSO4), filtered
and evaporated to give the corresponding oxime, which
was used as crude material in the next step.
4.1.5. 2,3,5-Tri-O-benzyl-4-O-methanesulfonyl-L-arabin-
ononitrile (14d). The nitrile 14d (1.27 g, 70% over two
steps) was prepared from 13d (1.55 g, 3.69 mmol) using
20
the procedure described for 14b. ½aꢁ +21 (c 1.58,
D
20
1
CHCl3) (lit.30 ½aꢁ +24 (c 1.45, CHCl3)); H NMR and
D
13C NMR spectra as for the enantiomer 14b; HRMS
(ESI) m/z calcd for C27H30NO6S 496.1794 (M+H)+,
found 496.1784.
A solution of the so-obtained oxime (1.46 g, 3.36 mmol)
in pyridine (5 mL) was slowly added to a cold (0 ꢁC)
solution of MsCl (1.72 mL, 22.4 mmol) in pyridine
(5 mL). The mixture was warmed to rt and left to react
for 3 h. The reaction was quenched with cold water
(30 mL) and the resulting solution was extracted with
EtOAc (2· 50 mL). The organic phases were combined,
dried (MgSO4) and evaporated to give 14b (1.27 g, 76%)
4.1.6. 2,3,5-Tri-O-benzyl-4-O-methanesulfonyl-D-ribono-
nitrile (14e). The nitrile 14e (1.25 g, 73% over two steps)
was prepared from 13e (1.45 g, 3.45 mmol) using the
20
procedure described for 14b. ½aꢁ +57 (c 2.2, CHCl3);
D
1H NMR (250 MHz, CDCl3) d 7.40–7.25 (m, 15H),
5.07 (m, 1H), 4.90 (d, 1H, J = 11.0 Hz), 4.82 (d, 1H,
J = 11.0 Hz), 4.72 (d, 1H, J = 11.0 Hz), 4.50 (m, 4H),
4.13 (m, 1H), 3.70 (m, 2H), 3.12 (s, 3H); 13C NMR
(62.5 MHz, CDCl3) d 137.6 (Cq), 136.9 (Cq), 135.5
(Cq), 129.2–128.3 (CH), 116.7 (Cq), 79.9 (CH), 78.1
(CH), 75.1 (CH2), 73.9 (CH2), 73.1 (CH2), 68.8 (CH2),
68.6 (CH), 39.1 (CH3); HRMS (ESI) m/z calcd for
C27H29NO6SNa 518.1613 (M+Na)+, found 518.1612.
as a colourless oil after purification by silica gel column
20
D
chromatography (petroleum ether/EtOAc 70:30). ½aꢁ
20
1
ꢀ21 (c 5.5, CHCl3) (lit.30 ½aꢁ ꢀ25 (c 1.0, CHCl3)); H
NMR (250 MHz, CDCl3) dD7.40–7.25 (m, 15H), 5.10
(m, 1H), 4.84 (d, 1H, J = 11.1 Hz), 4.82 (d, 1H,
J = 11.1 Hz), 4.71 (d, 1H, J = 11.1 Hz), 4.59 (d, 1H,
J = 11.1 Hz), 4.56 (s, 2H), 4.41 (d, 1H, J = 4.2 Hz),
4.10 (dd, 1H, J = 5.6, 4.2 Hz), 3.93 (dd, 1H, J = 11.2,
3.3 Hz), 3.79 (dd, 1H, J = 11.2, 6.1 Hz), 3.00 (s, 3H);
13C NMR (62.5 MHz, CDCl3) d 137.2 (Cq), 136.5
(Cq), 135.2 (Cq), 128.6–127.9 (CH), 116.5 (Cq), 78.8
(CH), 77.3 (CH), 75.0 (CH2), 73.5 (CH2), 73.1 (CH2),
68.0 (CH2), 67.4 (CH), 38.7 (CH3); HRMS (ESI) m/z
calcd for C27H29NO6SNa 518.1613 (M+Na)+, found
518.1625.
4.1.7. Representative procedure for the Ti-mediated cyclo-
propanation of glycononitriles: (5S,6R,7S)-6,7-dibenzyl-
oxy-5-benzyloxymethyl-4-azaspiro[2.4]heptane (15e).
A
solution of titrated ethylmagnesium bromide (2.2 mmol,
1–2 M in diethyl ether) was added at ꢀ78 ꢁC under ar-
gon to a solution of nitrile 14e (496 mg, 1 mmol) and
Ti(O-iPr)4 (330 lL, 1.1 mmol) in Et2O (25 mL). The yel-
low solution was warmed for ca. 1 h to 0 ꢁC. The orange
reaction mixture was warmed directly to room tempera-
ture (water bath) and after 10 min, BF3ÆOEt2 (0.25 mL,
2 mmol) was added. The solution was stirred for 1 h at rt
and 1 N HCl (3 mL) and ether (15 mL) were then added.
The resulting two clear phases were neutralized with
10% aq NaOH (10 mL) and the mixture was extracted
with diethyl ether (2· 30 mL). The combined organic
layers were dried (Na2SO4), filtered and concentrated
under reduced pressure. The residue was purified by sil-
4.1.3. 2,3:5,6-Di-O-isopropylidene-4-O-methanesulfonyl-
D-mannononitrile (14a). The nitrile 14a (934 mg, 49%
over two steps) was prepared from 13a (1.47 g,
20
5.65 mmol) using the procedure described for 14b. ½aꢁ
D
20
D
+48 (c 0.76, CHCl3) (lit.30 ½aꢁ +52 (c 1.0, CHCl3));
1H NMR (250 MHz, CDCl3)
d
4.92 (d, 1H,
J = 5.0 Hz), 4.80 (t, 1H, J = 9 Hz), 4.31–4.22 (m, 2H),
4.16–4.02 (m, 2H), 3.12 (s, 3H), 1.55 (s, 3H), 1.48 (s,
3H), 1.40 (s, 3H), 1.35 (s, 3H); 13C NMR (62.5 MHz,
CDCl3) d 117.0 (Cq), 112.4 (Cq), 112.0 (Cq), 81.2
(CH), 78.2 (CH), 74.5 (CH), 68.1 (CH2), 67.0 (CH),
39.3 (CH3), 27.3 (CH3), 26.6 (CH3), 26.0 (CH3), 25.8
(CH3); HRMS (ESI) m/z calcd for C13H22NO7S
336.1117 (M+H)+, found 336.1119.
ica gel flash chromatography (Et2O/NEt3 98:2) giving
20
D
15e (182 mg, 45%) as a colourless oil. ½aꢁ ꢀ34 (c 4.0,
1
CHCl3); H NMR (250 MHz, CDCl3) d 7.28–7.14 (m,
15H), 4.62 (d, 1 H, J = 12.0 Hz), 4.55–4.39 (m, 5H),
4.14 (dd, 1H, J = 5.8, 4.4 Hz), 3.74–3.61 (m, 2H),
3.56–3.45 (m, 2H), 2.41 (br s, NH), 0.98–0.85 (m, 1H),
0.68–0.50 (m, 2H), 0.26 (ddd, 1H, J = 10.2, 5.4,
3.3 Hz); 13C NMR (62.5 MHz, CDCl3) d 138.6 (Cq),
138.4 (Cq), 138.3 (Cq), 128.4–128.3 (CH), 127.7–127.4
(CH), 82.2 (CH), 80.3 (CH), 73.2 (CH2), 73.0 (CH2),
72.0 (CH2), 70.3 (CH2), 58.6 (CH), 42.8 (Cq), 11.9
(CH2), 8.5 (CH2); HRMS (ESI) m/z calcd for
C28H32NO3 430.2382 (M+H)+, found 430.2377.
4.1.4. 2,3,5-Tri-O-benzyl-4-O-methanesulfonyl-L-xylono-
nitrile (14c). The nitrile 14c (874 mg, 80% over two
steps) was prepared from 13c (925 mg, 2.20 mmol) using
20
the procedure described for 14b. ½aꢁ ꢀ39 (c 0.6,
D
1
CHCl3); H NMR (250 MHz, CDCl3) d 7.35–7.12 (m,
15H), 4.85 (q, 1H, J = 4.7 Hz), 4.76 (d, 1H,
J = 11.2 Hz), 4.71 (d, 1H, J = 11.2 Hz), 4.60 (d, 1H,
J = 11.1 Hz), 4.38 (d, 1H, J = 11.1 Hz), 4.37 (d, 1H,
J = 11.1 Hz), 4.28 (d, 1H, J = 11.1 Hz), 4.18 (d, 1H,
J = 4.5 Hz), 3.95 (t, 1H, J = 4.6 Hz), 3.64 (dd, 1H,
J = 10.9, 4.4 Hz), 3.48 (dd, 1H, J = 10.9, 5.4 Hz), 2.98
(s, 3H); 13C NMR (62.5 MHz, CDCl3) d 137.5 (Cq),
137.0 (Cq), 135.3 (Cq), 128.4–129.2 (CH), 116.6 (Cq),
79.2 (CH), 77.5 (CH), 75.9 (CH2), 73.9 (CH2), 73.2
(CH2), 68.6 (CH2), 67.5 (CH), 38.8 (CH3); HRMS
(ESI) m/z calcd for C27H29NO6SNa 518.1613
(M+Na)+, found 518.1594.
4.1.8.
(5S,6R,7S)-6,7-Di-O-isopropylidene-6,7-dihy-
droxy-5-[(1S)-1,2-di-O-isopropylidene-1,2-dihydroxyeth-
yl]-4-azaspiro[2.4]heptane (15a). The cyclopropane 15a
(127 mg, 38%) was prepared from 14a (420 mg,
20
D
1.25 mmol) using the procedure described for 15e. ½aꢁ
1
+36 (c 1.15, CHCl3); H NMR (250 MHz, CDCl3) d
4.45 (d, 1H, J = 5.6 Hz), 4.15–3.98 (m, 3H), 3.63 (t,
1H, J = 7.1 Hz), 3.18 (br d, 1H, J = 7.9 Hz), 2.81 (br s,
NH), 1.44 (s, 3H), 1.36 (s, 3H), 1.28 (s, 3H), 1.23 (s,

4052
C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
3H), 0.91–0.52 (m, 4H); 13C NMR (62.5 MHz, CDCl3) d
111.3 (Cq), 109.3 (Cq), 86.9 (CH), 84.5 (CH), 75.1 (CH),
68.2 (CH), 67.0 (CH2), 45.0 (Cq), 26.6 (CH3), 26.4
(CH3), 25.3 (CH3), 24.2 (CH3), 15.5 (CH2), 5.6 (CH2);
HRMS (ESI) m/z calcd for C14H24NO4 270.1705
(M+H)+, found 270.1702.
4.1.13. Representative procedure for the deprotection of
compounds 15b–e: (5S,6R,7R)-6,7-dihydroxy-5-hydroxy-
methyl-4-azaspiro[2.4]heptane (12b). A solution of 15b
(160 mg, 0.37 mmol), Boc2O (220 mg, 1 mmol) and
NEt3 (0.23 mL) in THF (5 mL) was stirred for 5 h at
rt. Water (5 mL) was then added and the solution was
extracted with EtOAc (2· 10 mL). The combined organ-
ic phases were dried and evaporated. The Boc derivative
was purified before debenzylation by silica gel chroma-
tography (petroleum ether/EtOAc 80:20). The fractions
with Rf = 0.5 were dissolved in MeOH (3 mL) and palla-
dium 10% on charcoal (72 mg) was added. Hydrogenol-
ysis was performed overnight and the reaction mixture
was filtered on a Celite pad and evaporated. Purification
by column chromatography (petroleum ether/EtOAc
10:90) gave the N-Boc pyrrolidine as a white solid
(73 mg, 76% from 15b). The compound was then treated
overnight with 1 M HCl. Evaporation of the solvents
gave a crude material, which was subjected to ion-ex-
change chromatography (Dowex 50WX-8 resin). Elu-
tion with 0.8 M NH4OH permitted to isolate pure 12b
4.1.9. (5S,6R,7R)-6,7-Dibenzyloxy-5-benzyloxymethyl-4-
azaspiro[2.4]heptane (15b). The cyclopropane 15b
(146 mg, 42%) was prepared from 14b (400 mg,
20
D
0.81 mmol) using the procedure described for 15e. ½aꢁ
+22 (c 3.4, CHCl3); 1H NMR (250 MHz, CDCl3) d
7.35–7.21 (m, 15H), 4.59–4.49 (m, 5H), 4.37 (d, 1H,
J = 12.1 Hz), 4.10 (dd, 1H, J = 4.2, 1.6 Hz), 3.75–3.59
(m, 4H), 1.81 (br s, NH), 0.96–0.55 (m, 4H); 13C
NMR (62.5 MHz, CDCl3) d 138.2 (Cq), 128.3–128.2
(CH), 127.7–127.3 (CH), 86.5 (CH), 84.5 (CH), 73.3
(CH2), 71.9 (CH2), 71.4 (CH2), 69.0 (CH2), 60.0 (CH),
44.3 (Cq), 12.4 (CH2), 8.1 (CH2); HRMS (ESI) m/z calcd
for C28H32NO3 430.2382 (M+H)+, found 430.2375.
4.1.10. (5R,6R,7R)-6,7-Dibenzyloxy-5-benzyloxymethyl-
4-azaspiro[2.4]heptane (15c). The cyclopropane 15c
(270 mg, 40%) was prepared from 14c (776 mg,
(26 mg, 44% from 15b) as a yellowish hygroscopic solid,
20
D
after lyophilization of the corresponding fractions. ½aꢁ
1
+40 (c 0.16, H2O); H NMR (250 MHz, D2O) d 4.10
(dd, 1H, J = 4.6, 1.6 Hz, H-6), 3.66 (dd, 1H, J = 11.2,
6.6 Hz, H-10a), 3.60 (d, 1H, J = 1.6 Hz, H-7), 3.53 (dd,
1H, J = 11.2, 6.6 Hz, H-10b), 3.36 (td, 1H, J = 6.6,
4.7 Hz, H-5), 0.72–0.50 (m, 4H); 13C NMR
(62.5 MHz, D2O) d 81.8 (CH), 78.2 (CH), 61.3 (CH),
60.5 (CH2), 45.0 (Cq), 12.2 (CH2), 6.1 (CH2); HRMS
(ESI) m/z calcd for C7H14NO3 160.0974 (M+H)+, found
160.0975.
20
1.57 mmol) using the procedure described for 15e. ½aꢁ
D
+52 (c 2.0, CHCl3); 1H NMR (250 MHz, CDCl3) d
7.35–7.25 (m, 15H), 4.57–4.51 (m, 5H), 4.45 (d, 1H,
J = 11.9 Hz), 4.04 (dd, 1H, J = 4.7, 1.6 Hz), 3.66–3.55
(m, 3H), 3.35 (q, 1H, J = 4.9 Hz), 2.51 (br s, NH),
0.95–0.66 (m, 3H), 0.62–0.52 (m, 1H); 13C NMR
(62.5 MHz, CDCl3) d 138.3 (Cq), 138.2 (Cq), 128.4–
128.3 (CH), 127.7–127.5 (CH), 88.5 (CH), 87.5 (CH),
73.2 (CH2), 71.9 (CH2), 70.9 (CH2), 70.0 (CH2), 63.9
(CH), 44.9 (Cq), 12.5 (CH2), 7.0 (CH2); HRMS (ESI)
m/z calcd for C28H32NO3 430.2382 (M+H)+, found
430.2387.
4.1.14. (5R,6R,7R)-6,7-Dihydroxy-5-hydroxymethyl-4-
azaspiro[2.4]heptane (12c). The cyclopropane 12c
(30 mg, 38% over three steps) was prepared from 15c
(215 mg, 0.50 mmol) using the procedure described for
20
4.1.11. (5R,6S,7S)-6,7-Dibenzyloxy-5-benzyloxymethyl-
4-azaspiro[2.4]heptane (15d). The cyclopropane 15d
(172 mg, 40%) was prepared from 14d (500 mg,
12b. ½aꢁ +58 (c 0.52, H2O); 1H NMR (250 MHz,
D2O) dD3.95 (dd, 1H, J = 5.4, 3.1 Hz, H-6), 3.77 (d,
1H, J = 3.1 Hz, H-7), 3.70 (t, 2H, J = 5.1 Hz, H-10a,b),
3.09 (dt, 1H, J = 5.4, 5.1 Hz, H-5), 0.83–0.62 (m, 4H);
13C NMR (62.5 MHz, D2O) d 82.1 (CH), 80.6 (CH),
65.4 (CH), 61.6 (CH2), 44.8 (Cq), 11.5 (CH2), 5.5
(CH2); HRMS (ESI) m/z calcd for C7H14NO3 160.0974
(M+H)+, found 160.0977.
20
1.01 mmol) using the procedure described for 15e. ½aꢁ
D
1
ꢀ24 (c 2.1, CHCl3); H NMR and 13C NMR spectra
as for the enantiomer 15b; HRMS (ESI) m/z calcd for
C28H32NO3 430.2382 (M+H)+, found 430.2375.
4.1.12. (5S,6R,7S)-6,7-Dihydroxy-5-[(1S)-1,2-dihydroxy-
ethyl]-4-azaspiro[2.4]heptane (12a). The diacetonide 15a
(127 mg, 0.47 mmol) was treated with a 1 M HCl solu-
tion (2 mL) overnight. Evaporation of the water gave
a crude material, which was subjected to ion-exchange
chromatography on a Dowex 50WX-8 resin (H+ form).
Elution with 0.8 M NH4OH permitted us to isolate pure
12a (81 mg, 91%) as a white solid, after lyophilization of
4.1.15.
(5R,6S,7S)-6,7-Dihydroxy-5-hydroxymethyl-4-
azaspiro[2.4]heptane (12d). The cyclopropane 12d
(34 mg, 45% over three steps) was prepared from 15d
(205 mg, 0.48 mmol) using the procedure described for
20
12b. ½aꢁ ꢀ36 (c 0.52, H2O); H NMR and 13C NMR
1
D
spectra as for the enantiomer 12b; HRMS (ESI) m/z
calcd for C7H14NO3 160.0974 (M+H)+, found 160.0972.
20
1
the corresponding fractions. ½aꢁ +3.3 (c 0.8, H2O); H
D
NMR (250 MHz, D2O) d 4.03 (dd, 1H, J = 8.1,
4.9 Hz, H-6), 3.63 (dt, 1H, J = 7.4, 4.2 Hz, H-10), 3.47
(d, 1H, J = 4.9 Hz, H-7), 3.45 (dd, 1H, J = 11.5,
4.2 Hz, H-20a), 3.23 (dd, 1H, J = 11.5, 7.4 Hz, H-20b),
2.96 (dd, 1H, J = 8.1, 4.2 Hz, H-5), 0.73–0.42 (m, 4H);
13C NMR (62.5 MHz, D2O) d 75.9 (CH), 73.5 (CH),
71.0 (CH), 64.0 (CH2), 63.2 (CH), 44.6 (Cq), 11.1
(CH2), 6.9 (CH2); HRMS (ESI) m/z calcd for
C8H16NO4 190.1079 (M+H)+, found 190.1085.
4.1.16.
(5S,6R,7S)-6,7-Dihydroxy-5-hydroxymethyl-4-
azaspiro[2.4]heptane (12e). The cyclopropane 12e
(38 mg, 38% over three steps) was prepared from 15e
(273 mg, 0.64 mmol) using the procedure described for
20
12b. ½aꢁ ꢀ47 (c 0.74, H2O); 1H NMR (250 MHz,
D2O) dD4.40 (dd, 1 H, J = 5.9, 4.7 Hz, H-6), 3.91 (d,
1 H, J = 4.7 Hz, H-7), 3.75 (dd, 1 H, J = 11.4, 5.9 Hz,
H-10a), 3.66 (dd, 1 H, J = 11.4, 5.9 Hz, H-10b), 3.35 (q,
1 H, J = 5.9 Hz, H-5), 0.90-0.50 (m, 4H); 13C NMR

C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
4053
15. Sinnott, M. L. Chem. Rev. 1990, 90, 1171.
16. Palcic, M. M.; Heerze, L. D.; Srivastava, O. P.; Hinsgaul,
O. J. Biol. Chem. 1989, 264, 17174.
17. Vasella, A.; Davies, G. J.; Bo¨hm, M. Curr. Opin. Chem.
Biol. 2002, 6, 619.
(62.5 MHz, D2O) d 75.4 (CH), 72.9 (CH), 60.4 (CH2),
60.3 (CH), 43.6 (Cq), 10.1 (CH2), 7.0 (CH2); HRMS
(ESI) m/z calcd for C7H14NO3 160.0974 (M+H)+, found
160.0969.
18. (a) Wong, C.-H.; Provencher, L.; Porco, J. A.; Jung, S.
H.; Wang, Y.-F.; Chen, L.; Wang, R.; Steensma, D. H.
J. Org. Chem. 1995, 60, 1492; For other inhibitors of L-
fucosidase, see, for example, (b) Beacham, A. R.; Smelt,
K. H.; Biggadike, K.; Britten, C. J.; Hackett, L.;
Winchester, B. G.; Nash, R. J.; Griffiths, R. C.; Fleet,
G. W. J. Tetrahedron Lett. 1998, 39, 151; Witczak, Z. J.;
Boryczewski, D. Bioorg. Med. Chem. Lett. 1998, 8, 3265;
Nishimura, Y.; Shitara, E.; Takeuchi, T. Tetrahedron
Lett. 1999, 40, 2351; Blaser, A.; Reymond, J.-L. Helv.
Chim. Acta 1999, 82, 760; Peer, A.; Vasella, A. Helv.
4.2. Enzymatic assays
The experiments were performed essentially as previous-
ly described.35 Briefly, 0.01–0.5 U/mL of enzyme
(1 U = 1 mol of glycoside hydrolyzed/min), preincubat-
ed for 5 min at 20 ꢁC with the inhibitor, and increasing
concentrations of aqueous solution of the appropriate
p-nitrophenyl glycoside substrates buffered to the opti-
mum pH of the enzyme were incubated for 20 min at
37 ꢁC (45 ꢁC for the amyloglucosidases). The reaction
was stopped by the addition of a 2.5 volumes of 0.2 M
sodium borate buffer, pH 9.8. The p-nitrophenolate
formed was quantified at 410 nM, and IC50 value was
calculated. Double-reciprocal (Lineweaver–Burk) plots
were used to determine the inhibition characteristics.
´
Chim. Acta 1999, 82, 1044; McCort, I.; Fort, S.; Dureault,
A.; Depezay, J.-C. Bioorg. Med. Chem. 2000, 8, 135;
Shitara, E.; Nishimura, Y.; Kojima, F.; Takeuchi, T.
Bioorg. Med. Chem. 2000, 8, 343; Blaser, A.; Reymond,
J.-L. Org. Lett. 2000, 2, 1733; Ogawa, S.; Sekura, R.;
Maruyama, A.; Odagiri, T.; Yuasa, H.; Hashimoto, H.
Carbohydr. Lett. 2000, 4, 13; Joubert, M.; Defoin, A.;
Tarnus, C.; Streith, J. Synlett 2000, 1366; Ogawa, S.;
Maruyama, A.; Odagiri, T.; Yuasa, H.; Hashimoto, H.
Eur. J. Org. Chem. 2001, 967; Robina, I.; Moreno-Vargas,
A. J.; Fernandez-Bolanos, J. G.; Fuentes, J.; Demange,
R.; Vogel, P. Bioorg. Med Chem. Lett. 2001, 11, 2555;
Blaser, A.; Reymond, J.-L. Helv. Chim. Acta 2001, 84,
2119; Yasuda, K.; Kizu, H.; Yamashita, T.; Kameda, Y.;
Kato, A.; Nash, R. J.; Fleet, G. W. J.; Molyneux, R. J.;
Asano, N. J. Nat. Prod 2002, 65, 198; Ogawa, S.;
Watanabe, M.; Maruyama, A.; Hisamatsu, S. Bioorg.
Med. Chem. Lett. 2002, 12, 749; Jensen, H. H.; Jensen, A.;
Hazell, R. G.; Bols, M. J. Chem. Soc., Perkin Trans.1
2002, 1190; Ogawa, S.; Mori, M.; Takeuchi, G.; Doi, F.;
Watanabe, M.; Sakata, Y. Bioorg. Med. Chem. Lett. 2002,
12, 2811; Moreno-Vargas, A. J.; Robina, I.; Demange, R.;
Vogel, P. Helv. Chim. Acta 2003, 86, 1894; Carmona, A.
T.; Popowycz, F.; Gerber-Lemaire, S.; Rodriguez-Garcia,
E.; Schuetz, C.; Vogel, P.; Robina, I. Bioorg. Med. Chem.
2003, 11, 4897; Painter, G. F.; Eldridge, P. J.; Falshaw, A.
Bioorg. Med. Chem. 2004, 12, 225; Tite, T.; Lallemand,
M.-C.; Poupon, E.; Kunesch, N.; Tillequin, F.; Gravier-
Pelletier, C.; Le Merrer, Y.; Husson, H.-P. Bioorg. Med.
Chem. 2004, 12, 5091; Kato, A.; Kato, N.; Kano, E.;
Adachi, I.; Ikeda, K.; Yu, L.; Okamoto, T.; Banba, Y.;
Ouchi, H.; Takahata, H.; Asano, N. J. Med. Chem. 2005,
Acknowledgments
The authors thank M. Choumane (undergraduate stu-
dent) for her help concerning 0technical aspects of this
`
work and the ‘Ministere de l Enseignement Superieur
et de la Recherche’ for a doctoral fellowship (C.L.)
´
References and notes
1. Kobata, A.. In Biology of Carbohydrates; Ginsburg, V.,
Robbins, P. W., Eds.; John Wiley and Sons: New York,
1984; 2, p 87.
2. Feizi, T. Nature 1985, 314, 53.
3. Hakomori, S. Adv. Cancer Res. 1989, 52, 257.
4. Varki, A. Glycobiology 1993, 3, 97.
5. Moloney, D. J.; Shair, L. H.; Lu, F. M.; Xia, J.; Locke, R.;
Matta, K. L.; Haltiwanger, R. S. J. Biol. Chem. 2000, 275,
9604.
6. Hiraishi, K.; Suzuki, K.; Hakamori, S.; Adachi, M.
Glycobiology 1993, 3, 381.
7. Ichikawa, Y.; Halcomb, R. L.; Wong, C.-H. Chem. Ber.
1994, 117.
´
48, 2036; Li, H.; Bleriot, Y.; Mallet, J.-M.; Rodriguez-
Garcia, E.; Vogel, P.; Zhang, Y.; Sinay, P. Tetrahedron:
8. Murray, B. W.; Takayama, S.; Schultz, J.; Wong, C.-H.
Biochemistry 1996, 35, 11183.
¨
Asymmetry 2005, 16, 313; Ogawa, S.; Asada, M.; Ooki,
Y.; Mori, M.; Itoh, M.; Korenaga, T. Bioorg. Med. Chem.
2005, 13, 4306.
9. Van der Marel, G. A.; Heskamp, B. M.; Veeneman, G. H.;
van Boeckel, C. A. A.; van Boom, J. H. In Carbohydrate
Mimics—Concepts and Methods; Chapleur, Y., Ed.;
Wiley-VCH: Weinheim, 1998; pp 491–510.
10. Ayude, D.; Fernandez-Rodriguez, J.; Rodriguez-Berrocal,
F. J.; Martinez-Zorzano, V. S.; de Carlos, A.; Gil, E.; de la
Cadena, M. P. Oncology 2000, 59, 310.
19. Chevrier, C.; LeNouen, D.; Neuburger, M.; Defoin, A.;
Tarnus, C. Tetrahedron Lett. 2004, 45, 5363.
20. Wang, Y. F.; Dumas, D. P.; Wong, C.-H. Tetrahedron
Lett. 1993, 34, 403.
21. Moreno-Vargas, A. J.; Carmona, A. T.; Mora, F.; Vogel,
P.; Robina, I. Chem. Commun. 2005, 4949.
22. (a) Palmer, A. M.; Ja¨ger, V. Eur. J. Org. Chem. 2001,
2547; (b) Sifferlen, T.; Defoin, A.; Streith, J.; LeNouen,
D.; Tarnus, C.; Dosbaa, I.; Foglietti, M.-J. Tetrahedron
2000, 56, 971.
11. Fernandez-Rodriguez, J.; Ayude, D.; de la Cadena, M. P.;
Martinez-Zorzano, V. S.; de Carlos, A.; Caride-Castro,
A.; de Castro, G.; Rodriguez-Berrocal, F. J. Cancer
Detect. Prev. 2000, 24, 143.
12. Robina, I.; Moreno-Vargas, A. J.; Carmona, A. T.; Vogel,
P. Curr. Drug Metab. 2004, 5, 329.
23. Asano, N.; Yasuda, K.; Kizu, H.; Kato, A.; Fan, J.-Q.;
Nash, R. J.; Fleet, G. W. J.; Molyneux, R. J. Eur. J.
Biochem. 2004, 268, 35.
24. Wong, C.-H.; Dumas, D. P.; Ichikawa, Y.; Koseki, K.;
Danishefsky, S. J.; Weston, B. W.; Lowe, J. B. J. Am.
Chem. Soc. 1992, 114, 7321.
13. Behr, J.-B.; Defoin, A.; Mahmood, N.; Streith, J. Helv.
Chim. Acta 1994, 78, 1166.
14. Fleet, G. W. J.; Karpas, A.; Dwek, R. A.; Fellows, L. E.;
Tyms, A. S.; Petursson, S.; Namgoong, S. K.; Ramsden, N.
G.; Smith, P. W.; Son, P. W.; Wilson, F.; Witty, D. R.;
Jacob, G. S.; Rademacher, T. W. FEBS Lett. 1988, 237, 128.

4054
C. Laroche et al. / Bioorg. Med. Chem. 14 (2006) 4047–4054
25. Compain, P.; Martin, O. R. Curr. Top. Med. Chem. 2003,
3, 541.
A. K.; Es-Sayed, M.; de Meijere, A. Eur. J. Org. Chem.
2002, 2499.
26. Schuster, M.; Blechert, S. Bioorg. Med. Chem. Lett. 2001,
11, 1809.
27. Laroche, C.; Behr, J.-B.; Szymoniak, J.; Bertus, P.;
Plantier-Royon, R. Eur. J. Org. Chem. 2005, 5084.
28. Laroche, C.; Plantier-Royon, R.; Szymoniak, J.; Bertus,
P.; Behr, J.-B. Synlett 2006, 223.
29. (a) Bertus, P.; Szymoniak, J. Chem. Commun. 2001, 1792;
(b) Bertus, P.; Szymoniak, J. J. Org. Chem. 2002, 67, 3965;
(c) Bertus, P.; Szymoniak, J. Synlett 2003, 265; (d)
Laroche, C.; Bertus, P.; Szymoniak, J. Tetrahedron Lett.
2003, 44, 2485; (e) Bertus, P.; Szymoniak, J. J. Org. Chem.
2003, 68, 7133; (f) Laroche, C.; Harakat, D.; Bertus, P.;
Szymoniak, J. Org. Biomol. Chem. 2005, 3, 3482; (g)
Gensini, M.; Kozhushkov, S. I.; Yufit, D. S.; Howard, J.
30. Buchanan, J. G.; Lumbard, K. W.; Sturgeon, R. J.;
Thompson, D. K.; Wightman, R. H. J. Chem. Soc., Perkin
Trans. 1 1990, 699.
31. De Meijere, A.; Kulinkovich, O. G. Chem. Rev. 2000, 100,
2789.
32. Behr, J.-B.; Erard, A.; Guillerm, G. Eur. J. Org. Chem.
2002, 1256.
33. Finch, P.; Iskander, G. M.; Siriwardena, A. H. Carbohydr.
Res. 1991, 210, 319.
34. Carmona, A. T.; Whightman, R. H.; Robina, I.; Vogel, P.
Helv. Chim. Acta 2003, 86, 3066.
35. Brandi, A.; Cicchi, S.; Cordero, F. M.; Frignoli, B.;
Goti, A.; Picasso, S.; Vogel, P. J. Org. Chem. 1995, 60,
6806.