Chiral 5-methyl-trihydroxypyrrolidines - Preparation from 1,2-oxazines and glycosidase inhibitory properties

Article abstract of DOI:10.1016/S0040-4020(99)01078-9

Chemical transformations of chiral 1,2-oxazines 4, 5 gave the 2,5,6- trideoxy-2,5-imino D-alditols 12b, 13b in the D-altritol and D-talitol series, respectively. Basic aldehyde epimerisation led to the D-allitol isomer 15b. Compound 12b is a potent α-L-fucosidase and α-D-galactosidase inhibitor. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(99)01078-9

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 971–978
Chiral 5-Methyl-trihydroxypyrrolidines—Preparation from
1,2-Oxazines and Glycosidase Inhibitory Properties
a
a
a
Thierry Sifferlen,a Albert Defoin,a, Jacques Streith, Didier Le Nouen, Celine Tarnus,
*
´
¨
b
ˆb
´
Isabelle Dosbaa and Marie-Jose Foglietti
a
´
´
´
´
´
Ecole Nationale Superieure de Chimie de Mulhouse, Universite de Haute-Alsace, 3, rue A. Werner, 68093 Mulhouse Cedex, France
b
´
Laboratoire de Biochimie et de Glycobiologie, Universite Rene Descartes, 4, Av. de l’Observatoire, 75006 Paris, France
Received 13 September 1999; accepted 14 December 1999
Abstract—Chemical transformations of chiral 1,2-oxazines 4, 5 gave the 2,5,6-trideoxy-2,5-imino d-alditols 12b, 13b in the d-altritol and
d-talitol series, respectively. Basic aldehyde epimerisation led to the d-allitol isomer 15b. Compound 12b is a potent a-l-fucosidase and
a-d-galactosidase inhibitor. ᭧ 2000 Elsevier Science Ltd. All rights reserved.
Introduction
family (Sophoreae tribu) and is a weak b-d-mannosi-
dase inhibitor.8
Polyhydroxypiperidine and polyhydroxypyrrolidine amino-
sugars are monosaccharide analogues which mimic
these sugars in their pyranose or furanose forms so
that they are generally potent inhibitors of the corre-
sponding glycosidases.1 Among these amino-sugars,
type 1a–c 5-methyl-polyhydroxypyrrolidines, which are
also called v-deoxy-aza-sugars, have been recently
synthesised and studied as glycosidase inhibitors.
l-Arabinose derivatives of type 1b,c are potent
a-l-rhamnosidase inhibitors;2 the (^)-ribose analogues
were synthesised, but not tested.3 Some 5-methyl-pyrroli-
dine-triols 1a were obtained by chemio-enzymatic synth-
esis by Wong et al.4–6 and proved to be a-l-fucosidase
inhibitors,4,5 and also rather weak a-[1,3]-fucosyl-transfer-
ase inhibitors.7 The all-trans isomer is a natural product
isolated from the seeds of a tree of the Leguminoseae
We have already described the de novo chiral synthesis of
6-deoxy-nojirimycin and of some of its isomers from sorbal-
dehyde dimethylacetal 2 via asymmetric hetero-Diels–
Alder cycloaddition with the a-chloronitroso-d-mannose
derivative 3 and with excellent asymmetric induction
(eeϾ99%); chemical modifications of the primary Diels–
Alder adduct gave the intermediate oxazane-diols 4 and 5
(Scheme 1).9 Starting from these two diols, we describe
herein the synthesis of three 5-methyl-trihydroxy-
pyrrolidines of type 1a, as well as their glycosidase
inhibitory properties. The principle of this synthesis is a
ring reduction of 1,2-oxazane in pyrrolidine and a base-
catalysed epimerisation of the aldehyde group. A pre-
liminary communication relating to this work has already
been published.10
Scheme 1.
Keywords: trihydroxypyrrolidines; glycosidases inhibitions.
* Corresponding author. Fax: ϩ33-03-89-33-68-15; e-mail: a.defoin@univ-mulhouse.fr
0040–4020/00/$ - see front matter ᭧ 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(99)01078-9

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T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
Synthesis of Pyrrolidine Ring
trideoxy-2,5-imino-d-altritol) and the oily 13b (2,5,6-
trideoxy-2,5-imino-d-talitol) in 80–85% yields from the
corresponding alcohols 10c, 11c. In these syntheses, inter-
mediary compounds are generally not purified and only
Modifications of the oxazane ring required protection of the
diol moieties in 4, 5 as acetonides 6, 7, respectively, which
was achieved according to Ref. 11 in dimethoxy-propane
with Amberlyst-15 (Hϩ) as catalyst. Hydrogenolysis of the
N–O bond over Pd/C as described earlier for the diols 4, 59
led to the linear protected 5-amino-5,6-dideoxy-d-hexoses
8a, 9a, in the d-allose and d-fucose series, respectively,
which were N-reprotected at once with benzyl chloroformi-
ate in aqueous 1N NaOH to give 8b, 9b in 67–80% overall
yields from the diols 4, 5 after chromatographic purification.
Esterification of the remaining alcohol function with
methane sulfonyl chloride and NEt3 gave quantitatively
the mesylates 8c, 9c which were easily cyclised to the
protected 2,5-trans pyrrolidines 10a, 11a, respectively,
with aq. 2.5 N NaOH in EtOH at 80ЊC in 70–75% yield
after chromatography (Scheme 2).
1
characterised by H NMR.
The enantiomer of the talitol derivative 13b was assumed
by Wong to have been obtained by chemio-enzymatic
synthesis,4 nevertheless its physical properties are quite
different from those of 13b as obtained by us and correspond
presumably to another isomer13 (see Structural Analysis).
Aldehyde Epimerisation
Isomeric aldehydes 10b, 11b appear to be stable compounds
under normal conditions, nevertheless they cannot be
chromatographed without some degradations. They present
in their 1H NMR spectra two sets of distinct resonances for
two rotamers at 300 K; the origin of this unusual highly
hindered internal rotation of the carbamate N–CO2Bn
moiety14 is probably a steric bulkiness between this group
and the two neighbouring substituents, the CHO(1) and the
Me(6) groups. This bulkiness is particulary severe for 10b
because of the proximity of the acetonide ring, so that, even
Selective acidic deprotection of the acetal moiety was
carried out in dry acetone with Amberlyst-15 (Hϩ), accord-
ing to Coppola’s method12 at 40ЊC and led easily to
aldehyde 10b from 10a, but its isomer 11b from 11a was
more difficult to obtain.
1
Crude aldehydes 10b, 11b were reduced by NaBH4 in
MeOH into the corresponding alcohols 10c, 11c in 67 and
78% yield from acetals 10a, 11a, respectively. Deprotection
of these alcohols by Amberlyst-15 (Hϩ) in MeOH into 12a,
13a, then by hydrogenolysis over Pd/C, led to the final
trihydroxypyrrolidines, i.e. to the crystalline 12b (2,5,6-
at 330 K, the H NMR spectrum was not resolved.
The supposed instability of some similar pyrrolidine-2-
carbaldehydes, which is reported in the literature,15 was
usually explained as a spontaneous epimerisation and is
probably attributed to such a rotamery.
Scheme 2. (a) Dimethoxypropane/Amberlyst 15 (Hϩ). (b) H2/Pd–C. (c) ClCO2Bn/NaOH. (d)ClSO2Me/NEt3. (e) 1 N NaOH/MeOH. (f) Amberlyst 15 (Hϩ)/
acetone. (g) NaBH4/MeOH. (h) Amberlyst 15 (Hϩ)/EtOH. (i)CO3Na2/MeOH. (j) Hϩ/MeOH.

T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
973
Table 1. Glycosidases inhibition values as IC50 or (Ki) for pyrrolidines 12b, 13b, 15b [a-d-glucosidase from yeast, b-d-glucosidases from almond, a-d-
mannosidase from Jack bean, a-l-fucosidase from bovine kidney, a-d-galactosidase from green coffee beans; n.i.: no or weak (IC50Ͼ1 mM) inhibition]
a-d-Glucosidase
b-d-Glucosidase
a-d-Mannosidase
a-l-Fucosidase
a-d-Galactosidase
12b
13b
15b
1618
n.i.
n.i.
n.i.
n.i.
1.2 mM
(100 mM)
n.i.
(53 mM)
n.i.a
n.i.
(9 mM)
1 mM
(120 mM)
n.i.
(5 mM)
2 mM
(70 mM)
0.2 mM
350 mM
14 mM
a Activation (ϩ78% at 1 mM).
Epimerisation of the carbaldehyde group of 10b was pos-
sible indeed, but it required basic conditions; in this case
Na2CO3 in MeOH was a strong enough base to trigger
complete epimerisation into the thermodynamically more
stable 2,5-cis isomer 14a after 1 h at rt.16 Attemps to
epimerise its isomer 11b failed using the same experimental
conditions; more drastic conditions led to degradation. In
this latter case, the formation of the all-cis isomer is
obviously not favoured.
ascertained with the derivative 13a by nOe experiments:
irradiation of CH2(1) signals gave an enhancement of 8
and 6% of the ones of HC(3) and H-C(4), respectively;
irradiation of H-C(5) signal gave an enhancement of 6%
of the one of H-C(4).
Inhibitions of Glycosidases
The inhibition properties of pyrrolidine-triols 12b, 13b, 15b
on various glycosidases are reported in Table 1. Inhibition
constants (Ki) determined for the most potent derivatives
indicate a competitive inhibition. It is noteworthy that
a-l-fucosidase and a-d-galactosidase show similar inhibi-
tion profiles with the three evaluated compounds. It under-
lines the importance of the cis-2,3-diol group in these
pyrrolidines similar to the structure of the parent sugars,
a-l-fucose and a-d-galactose. In addition, the presence of
the CH2OH functionality improves the affinity when
the same orientation as the cis-diol group is considered,
d-altritol 12b being ca. 10 times more potent on both
enzymes than d-allitol 15b. The activity of the other studied
glucosidases is not significantly inhibited by these
compounds, except 13b on b-d-glucosidase (Kiˆ100 mM)
and 12b on a-d-mannosidase (Kiˆ53 mM).
Immediate reduction of 14a by addition of NaBH4 to the
isomerisation solution gave directly the corresponding
alcohol 14b in 54% yield from 10b. Deprotection in 15a
with Amberlyst 15 (Hϩ) followed by hydrogenolysis over
Pd/C, led to trihydroxypyrrolidine (2,5,6-trideoxy-2,5-
imino-d-allitol) 15b in 87% yield.
Structural Analysis of the Pyrrolidines
1H NMR data of the synthesised pyrrolidines 10a–c, 11a–c,
14a,b, 12a,b, 13a,b, 15a,b were carefully determined
because of strong rotation hindrances for the N-acyl
derivatives and are presented in Table 2 (see Experimental).
The structures of these products could be ascertained
unambiguously by the chemical transformations which
were carried out starting from the oxazane-diols 4, 5. Never-
theless, in the N-acylated pyrrolidines, steric interaction
between the N-acyl group and the substituents in 2- and
5-positions forces the pyrrolidine ring to adopt a conforma-
tion in which the dihedral angles of both trans vicinal
H-C(2), H-C(3) and/or H-C(4), H-C(5) protons are close
to 90Њ, so that the corresponding couplings are small or
null (0–2.5 Hz). This is clearly observed for the trans
vicinal couplings J(2,3) in 11a–c, 13a; for J(2,3) and
J(4,5) in 14a,b and for J(4,5) in 10a–c, 12a.
Comparison of our results for 12b with literature data
related to compound 1618 (Table 1) shows that the presence
of the methyl-(6) substituent is essential for the recognition
by a-l-fucosidase. An orientation of this methyl group
identical to l-fucose should increase the affinity to the
enzyme.
Conclusion
We have presented a simple synthesis as well as the glyco-
sidase inhibitor properties of three pyrrolidine-triols, start-
ing from the known oxazane-diols 4 and 5, with overall
yields of 31% for 12b and 27% for 15b from diol 4, and
of 33% for 13b from diol 5.
Similar results have been observed for methyl furanosides in
which the anomeric effect favours a quasi-axial position for
the anomeric substituent so that trans J(1,2) values are small
(0–1.5 Hz).17
As a consequence, the suppression of this steric bulkiness by
N-deprotection led to a conformational change for the final
pyrrolidines 12b, 13b, 15b and the above trans-couplings
are larger (5–9 Hz, see Table 2).
Experimental
General
Flash chromatography (FC): silica gel (Merck 60, 230–400
mesh). TLC: Al-roll silica gel (Merck 60, F254). Mp: Kofler
hot bench or Bu¨chi-SMP20 apparatus, corrected. IR spectra
(n in cmϪ1): Perkin–Elmer 157 G, [a]D: Schmidt-Haensch
Polartronic Universal polarimeter. HPLC measurements:
If we consider, in particular, the case of 13b, its stereo-
structure results from one of its N-acylated derivatives
11c, 13a and the relative position of the CH2OH(1) group
on the same side as H-C(3), H-C(4) and H-C(5) was

974
T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
liquid chromatograph Hewlett-Packard 190. 1H and 13C
NMR (62.9 MHz) spectra: Bruker AC-F250; tetramethyl-
silane (TMS) in CDCl3, CD3OD (d(CD3OD)ˆ3.30), (D6)-
DMSO (d((D6)-DMSO)ˆ2.50) or natrium (D4)-trimethyl-
silyl-propionate (D4-TSP) in D2O (1H-NMR) and CDCl3,
CD3OD, or (in D2O) CH3OH or dioxane [d(CDCl3)ˆ77.0,
d(CD3OD)ˆ49.0, in D2O d(CH3OH)ˆ50.0, d(dioxane)ˆ
67.4 with respect to TMS] (13C-NMR) as internal refer-
ences; d in ppm and J in Hz. 13C attributions were ascer-
tained by 1H–13C correlation. NOe experiments were
carried out in argon saturated solutions. High resolution
(HR)-MS were measured on a MAT-311 spectrometer at
the University of Rennes. Microanalyses were carried out
by the Service Central de Microanalyses du CNRS, F-69390
Vernaison, or Service de Microanalyse de l’ICSN-CNRS,
F-91168 Gif sur Yvette.
300 K): 7.36 (m, 5 H arom.); 5.24, 5.13 (2d, Jˆ12.2 Hz,
CH2Ph); 4.69 (d, Jˆ8.0 Hz, H-C(10)); 4.38 (m, H-C(3),
H-C(4)); 4.24 (m, H-C(5)); 4.11 (dd, Jˆ3.0 Hz, 8.0 Hz,
H-C(6)); 3.44, 3.34 (2s, 2 OMe); 1.53,1.35 (2s, 2 Me);
1
1.30 (m, Me HzC(3)). H NMR (C6D6, 300 K): 7.27 (m, 2
H arom.); 7.08 (m, 3 H arom.); 5.13, 5.05 (2d, Jˆ12.4 Hz,
CH2Ph); 4.87 (d, H-C(10)); 4.42 (quint., H-C(3)); 3.93 (dd,
H-C(4)); 4.01 (dd, H-C(5)); 4.11 (dd, H-C(6)); 3.22, 3.40
(2s, 2 OMe); 1.39 (d, Me-C(3)); 1.39, 1.15 (2s, 2 Me).
J(10,6)ˆ8.0 Hz, J(3,4)ˆ7.3 Hz, J(3,Me-3)ˆ6.9 Hz, J(4,5)ˆ
6.1 Hz, J(5,6)ˆ2.8 Hz. 13C NMR (CDCl3, 300 K): 154.8
(NCO2); 135.7, 128.5, 128.3, 128.2 (Ph); 109.6 (CMe2));
99.9 (C(10)); 78.3 (C(6)); 71.2 (C(5)); 70.7 (CH2Ph); 67.8
(C(4)); 56.0 (OMe); 51.5 (C(3)); 50.9 (OMe); 25.6, 25.5 (2
Me); 14.6 (Me HzC(3)). Rfˆ0.48 (AcOEt/cyclohexane 1:1).
Anal. calcd for C19H27NO7 (381.42): C 59.83, H 7.14, N
3.67; found: C 59.9, H 7.1, N 3.7.
Reagents and solvents: 5% Pd/C catalyst, benzyl chloro-
formate, 2,2-dimethoxypropane, MeSO2Cl were purchased
from Fluka, Amberlyst-15 from Rohm & Haas, triethyl-
amine was distilled. Usual solvents were freshly distilled,
dry EtOH and MeOH distilled over Mg/MgI2, CH2Cl2 was
kept over Na2CO3.
Pyrrolidine derivatives
5-Amino-3,4-O-isopropylidene-5,6-dideoxy-d-allose
dimethylacetal (8a) and 5-(benzyloxy-carbonylamino)-
3,4-O-isopropylidene-5,6-dideoxy-d-allose dimethyl-
acetal (8b). A solution of crude 6 (2.07 g corresponding
to 5.06 mmol) in EtOH (8 ml) was hydrogenolysed over
5% Pd/C (0.1 g) at 50ЊC for 1 day (after 8 h, another 0.1 g
Pd/C was added). The catalyst was discarded by centrifuga-
tion, washed with EtOH and the solvents were evaporated to
give crude 8a (1.4 g, quant.).
1,2-Oxazane derivatives
Benzyl (3R)-t-4,t-5-isopropylidenedioxy-c-6-dimethoxy-
methyl-r-3-methyl-1,2-oxazane-2-carboxylate (6). To a
solution of diol 49 (2.21 g, 6.48 mmol) in 2,2-dimethoxy-
propane (8 ml) was added Amberlyst-15 (Hϩ) (0.13 g) and
the solution was stirred at 40ЊC for 2 h. The catalyst was
discarded by filtration, washed with acetone and the
solvents were evaporated to give 6 as a brownish oil
(2.6 g, quant.). For analytical purposes, it was purified by
FC (AcOEt/cyclohexane, 1:1).
To a stirred solution of crude 8a (1.4 g, 5.06 mmol) in
distilled water (10 ml) was added aq. 2.5 N NaOH (6 ml,
15 mmol) and ClCO2Bn (1.1 ml, 7.6 mmol, 1.5 equiv.).
After 3 h at rt, the solution was extracted with CH2Cl2
(5×5 ml), the organic phases were dried (MgSO4) and
evaporated. The resulting yellow oil (2.3 g) was purified
by FC (AcOEt/cyclohexane, 1:1 on 100 g silica gel) and
gave pure 8b (1.55 g, 80% yield from 4).
6: yellowish oil, [a]D20ˆϪ99 (cˆ1.0, CHCl3). IR (CHCl3):
2985, 2925, 1705, 1450, 1405, 1385, 1355, 1330, 1305,
1
1290, 1230, 1130, 1070, 900, 865, 695. H NMR (CDCl3,
298 K): 7.36 (m, 5H arom.); 5.15, 5.27 (2d, Jˆ12.3 Hz,
CH2Ph); 4.64 (dq, H-C(3)); 4.43 (d, H-C(10)); 4.35 (dd,
H-C(5)); 4.05 (dd, H-C(4)); 3.97 (dd, H-C(6)); 3.42, 3.44
(2s, 2 OMe); 1.36 (d, Me-C(3)); 1.33, 1.36 (2s, 2 Me).
J(3,4)ˆ1.2 Hz, J(3,Me-3)ˆ7.2 Hz, J(4,5)ˆ5.2 Hz, J(5,6)ˆ
8.8 Hz, J(6,10)ˆ3.4 Hz. 13C NMR (CDCl3, 300 K): 155.5
(NCO2); 136.0, 128.4, 128.2, 128.2 (Ph); 109.7 (CMe2));
102.3 (C(10)); 79.3 (C(6)); 74.7 (C(4)); 68.9 (C(5)); 67.7
(CH2Ph); 54.8, 54.5 (2 OMe); 51.5 (C(3)); 28.0, 26.3 (2
Me); 16.0 (Me-C(3)). Rfˆ0.36 (AcOEt/cyclohexane 1:1).
Anal. calcd for C19H27NO7 (381.42): C 59.83, H 7.14, N
3.67; found: C 59.5, H 7.1, N 3.7.
8a: yellowish oil characterised by 1H NMR (CDCl3, 300 K):
4.51 (d, H-C(1)); 4.25 (dd, H-C(3)); 3.86 (dd, H-C(2)); 3.80
(dd, H-C(4)); 3.55, 3.50 (2 s, 2 OMe); 3.15 (dq, H-C(5));
2.62 (broad s, OH, NH2); 1.40, 1.34 (2 s, 2 Me); 1.26 (d,
Me(6)). J(1,2)ˆ1.8 Hz, J(2,3)ˆ9.6 Hz, J(3,4)ˆ5.4 Hz,
J(4,5)ˆ9.4 Hz, J(5,Me(6))ˆ6.4 Hz.
8b: yellow oil. [a]D20ˆϪ4 (cˆ1.0, CHCl3). IR (CHCl3):
3560, 3435, 2990, 2935, 2840, 1710, 1510, 1450, 1380,
1370, 1230, 1070, 910, 870, 695. 1H NMR (CDCl3,
298 K): 7.32 (m, 5 H arom.); 5.08, 5.10 (2d, Jˆ12.4 Hz,
CH2Ph); 5.39 (d, NH-C(5)); 4.47 (d, H-C(1)); 3.80 (ddd,
H-C(2)); 4.08 (dd, H-C(3)); 4.16 (dd, H-C(4)); 4.05 (ddq,
H-C(5)); 3.54, 3.44 (2s, 2 OMe); 2.54 (d, OH-C(2));
1.42, 1.34 (2s, 2 Me); 1.30 (d, Me(6)). J(1,2)ˆ1.8 Hz,
Benzyl (3R)-c-4,c-5-isopropylidenedioxy-c-6-dimethoxy-
methyl-r-3-methyl-1,2-oxazane-2-carboxylate (7). Same
procedure as for 6 from diol 59 (2.65 g, 7.75 mmol) in
2,2-dimethoxypropane (10 ml) with Amberlyst-15 (Hϩ)
(0.16 g) at 45ЊC for 5 h to give pure 7 after washing with
cold i-Pr2O (1.975 g, 67%).
J(2,OH-2)ˆ4.8 Hz,
J(2,3)ˆ9.6 Hz,
J(3,4)ˆ5.4 Hz,
J(4,5)ˆ 6.0 Hz, J(5,Me(6))ˆ6.6 Hz, J(5,NH-5)ˆ8.0 Hz.
Rfˆ0.28 (AcOEt/cyclohexane 1:1). Anal. calcd for
C19H29NO7 (383.44): C 59.51, H 7.62, N 3.65; found: C
59.3, H 7.7, N 3.6.
7: beige crystals. Mpˆ107–108ЊC (i-Pr2O/cyclohexane).
[a]2D1ˆϪ40 (cˆ1.0, CHCl3). IR (KBr): 2980, 2930, 1695,
1410, 1375, 1350, 1300, 1245, 1210, 1135, 1100, 1070,
5-(Benzyloxycarbonylamino)-3,4-O-isopropylidene-2-O-
methanesulfonyl-5,6-dideoxy-d-allose dimethylacetal
(8c) and 2,5-(benzyloxycarbonylimino)-3,4-O-isopropyl-
1
1045, 1025, 1010, 965, 875, 750, 700. H NMR (CDCl3,

T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
975
1
Table 2. H NMR data (CDCl3) of pyrrolidines 10a–c, 12a,b, 11a–c, 13a,b, 14a,b, 15a,b (250 MHz, 300 K, d in ppm, J in Hz)
a
Ha-C(1)
Hb-C(1)
H-C(2)
H-C(3)
H-C(4)
H-C(5)
Me(6)
CH2
Meb
10ac
5.09
9.32
9.43
3.82
4.14
4.15
3.78
3.75
3.39
4.11
4.54
3.97
3.86
3.64
3.10
3.18
4.57
4.13
3.81
3.09
4.75
5.03
4.99
4.75
4.51
4.20
4.79
4.67
4.54
4.08
4.02
3.95
4.04
4.92
4.61
4.12
3.92
4.26
4.47
4.47
4.30
3.80
3.71
4.57
4.59
4.62
4.23
4.16
3.82
3.96
4.34
4.34
3.86
3.60
4.14
4.36
4.28
4.19
3.93
3.06
3.91
3.95
4.04
4.01
3.81
3.15
3.24
4.33
4.17
3.93
3.05
1.23
1.23
1.14
1.12
1.16
1.20
1.38
1.43
1.34
1.32
1.20
1.14
1.14
1.15
1.25
1.22
1.22
5.11
5.10
5.12
5.13
5.07
5.12
5.12
5.23
5.18
5.19
1.30
1.28
1.28
1.28
1.46
1.43
1.46
1.42
10bd maj
min
10ce
3.92
4.26
3.77
3.96
3.99
3.60
12a
12bf
11ag,h
11bi
4.43
9.59
5.08
5.25
1.33
1.33
1.33
1.47
1.50
1.48
5.11
11ch,j
13ah,k
13al
3.70
3.73
3.53
3.65
3.70
3.92
3.73
3.44
3.58
3.63
5.11
5.12
5.05
5.16
5.16
5.10
13bm
13bf
14ah
14bi,n
15ai,o
15bf
9.66
5.19
5.15
5.15
1.32
1.30
1.45
1.44
3.75
3.87
3.71
3.70
3.78
3.67
J(1a,1b)
J(1a,2)
J(1b,2)
J(2,3)
J(3,4)
J(4,5)
J(5,6)
10a
6.4
3.3
3.4
5.4
7.2
6.6
5.5
8.7
4.4
0
2.0
2.0
2.6
1.1
7.7
7.7
1.9
1.9
5.6
5.2
6.2
5.8
5.8
6.2
4.8
4.4
6.3
6.2
6.3
4.9
4.6
4.4
4.4
5.6
5.7
4.0
6.1
1.9
0
0
0
0
8.8
6.5
5.8
6.2
7.2
7.8
3.3
3.4
0
6.8
6.9
6.9
7.0
6.7
6.4
6.5
6.5
6.6
6.6
6.6
6.7
6.7
7.0
6.9
6.7
6.5
10bd maj.
min.
10c
12.7
11.4
11.0
4.8
3.4
6.8
4.8
nd
6.8
12a
12bf
11a
1.5
1.4
11b
11cj
13a
11.2
4.0
4.6
3.3
4.2
4.6
4.0
4.6
6.5
5.8
6.3
13al
13bm
13bf
14a
10.8
11.2
11.5
0
14bn
15a
11.1
10.2
11.6
5.4
2.9
5.1
5.4
4.9
5.6
1.4
2.4
7.3
15bf
a Benzyl protons, Jˆ12.3 Hz, Ph: 7.30–7.38.
b Acetonide methyls.
c Acetal OMe: 3.47, 3.48.
d Two rotamers.
i 333 K.
j OH–C(1): 2.3 (br. s), J(1a,OH-1)ˆJ(1b,OH-1)ˆ4.8 Hz.
k 3 OH: ca. 2.8, 2.83, 2.65 (3 br. s); J(1a,OH-1)ˆJ(1b,OH-1)ˆ6.2 Hz.
l In (D6)-DMSO, 350 K, 3 OH: ca. 4.45 (br. s).
e 330 K, OH–C(1): 4.6 (br. s).
f In D2O.
m In CD3OD.
n OH–C(1): 2.2 (br. s), J(1a,OH-1)ˆ4.8 Hz, J(1b,OH-1)ˆ6.2 Hz.
o 400 MHz, 3 OH: 2.32 (d, Jˆ3.6 Hz), 2.37 (d, Jˆ5.7 Hz), 2.84 (s).
g Acetal OMe: 3.30, 3.38.
h 336 K.
1
idene-2,5,6-trideoxy-d-altrose dimethylacetal (benzyl
(2S)-c-3,c-4-isopropylidenedioxy-r-2-dimethoxymethyl-
t-5-methyl-pyrrolidine-1-carboxylate, 10a). To a stirred
solution of 8b (1.56 g, 4.08 mmol) and NEt3 (0.7 ml,
5.1 mmol, 1.25 equiv.) in CH2Cl2 (9 ml), was added at
Ϫ10ЊC MeSO2Cl (0.35 ml, 4.5 mmol, 1.1 equiv.). After
1 h at Ϫ10ЊC, Et2O (20 ml) was added, the organic
phase was washed with water (3×10 ml), the aqueous
phases were extracted with Et2O (3×10 ml), the organic
phases dried (MgSO4) and evaporated to give 8c (1.88 g,
quant.).
8c: yellow oil, characterised by H NMR (CDCl3, 298 K):
7.33 (m, 5 H arom.); 5.34 (d, NH-C(5)); 5.07 (s, CH2Ph);
4.92 (dd, H-C(2)); 4.58 (d, H-C(1)); 4.41 (dd, H-C(3)); 4.35
(dd, H-C(4)); 3.81 (sext., H-C(5)); 3.52, 3.47 (2 s, 2 OMe);
3.20 (s, SO2Me); 1.45, 1.36 (2s, 2 Me); 1.34 (d, Me(6)).
J(1,2)ˆ2.6 Hz, J(2,3)ˆ6.8 Hz, J(3,4)ˆ5.7 Hz, J(4,5)ˆ
7.0 Hz, J(5,NH-5)ˆ7.8 Hz, J(5,Me(6))ˆ6.8 Hz. Rfˆ0.39
(AcOEt/cyclohexane 1:1).
10a: yellow oil, [a]D20ˆϪ46 (cˆ1.0, CHCl3). IR (CHCl3):
2980, 2930, 1700, 1450, 1410, 1380, 1350, 1290, 1235,
1
1185, 1120 1065, 965, 865, 690. H NMR: see Table 2.
A solution of 8c (1.82 g, 3.95 mmol) in EtOH (2.5 ml) and
aq. 2.5N NaOH (4.75 ml, 11.8 mmol, 3 equiv.) was stirred
at 80ЊC for 1.5 day. H2O (15 ml) was added and the solution
was extracted with AcOEt (3×10 ml), the organic phases
were dried (MgSO4) and evaporated. Crude 10a (1.2 g)
was purified by FC (CH2Cl2/Et2O 9:1 on 60 g silica gel)
to give pure 10a (1.03 g, 72% yield from 8b).
13C NMR (CDCl3, 300 K): 155.2 (NCO2); 136.6, 128.4,
128.0, 127.9 (Ph); 112.2 (CMe2)); 103.9 (C(1)); 84.3
(C(4)); 79.0 (C(3)); 66.8 (CH2Ph); 62.2 (C(2)); 59.8
(C(5)); 57.1, 56.2 (2 OMe); 26.1, 24.7 (2 Me); 17.1
(Me(6)). Rfˆ0.37 (CH2Cl2/Et2O 9:1). Anal. calcd for
C19H27NO6 (365.42): C 62.45, H 7.45, N 3.83; found: C
61.9, H 7.5, N 3.8.

976
T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
5-Amino-3,4-O-isopropylidene-5,6-dideoxy-d-fucose
dimethylacetal (9a), 5-(benzyloxy-carbonylamino)-3,4-
O-isopropylidene-5,6-dideoxy-d-fucose dimethylacetal (9b),
5-(benzyloxycarbonylamino)-3,4-O-isopropylidene-2-O-
methanesulfonyl-5,6-dideoxy-d-fucose dimethylacetal
(9c) and 2,5-(benzyloxycarbonylimino)-3,4-O-isopropyl-
idene-2,5,6-trideoxy-d-talose dimethylacetal (benzyl
(2S)-t-3,t-4-isopropylidenedioxy-r-2-dimethoxymethyl-t-
5-methyl-pyrrolidine-1-carboxylate, (11a)). Same pro-
cedure as for 8a from 7 (1.675 g, 4.39 mmol) in EtOH
(17 ml) over 5% Pd/C (88 mg) at 50ЊC for 14 h to give
crude 9a (1.3 g, quant.) which was N-protected as for 8b
in H2O (8 ml), 2.5 N NaOH (5.3 ml), with ClCO2Bn
(0.93 ml, 6.59 mmol, 1.5 equiv.) for 4.5 h at rt. Purification
by FC (AcOEt/cyclohexane 1:1) gave pure 9b (1.68 g,
quant.).
(Hϩ) (0.28 g, 0.1 g pro mmol acetal). The catalyst was
discarded by filtration and washed with acetone, the
solvents were evaporated to give crude 10b.
10b: characterised by 1H NMR (two rotamers ca. 55:45): see
Table 2.
2,5-(Benzyloxycarbonylimino)-3,4-O-isopropylidene-2,
5,6-trideoxy-d-altritol (benzyl (2R)-r-2-hydroxymethyl-
c-3,c-4-isopropylidenedioxy-t-5-methyl-pyrrolidine-1-
carboxylate, (10c)). To a stirred solution of crude 10b
(0.274 g, 0.79 mmol) in dry MeOH (1.5 ml) under Ar was
added NaBH4 (60 mg, 1.58 mmol, 2 equiv.). After 30 min at
rt, acetone (2 ml), aq. 1N HCl (0.8 ml, 0.8 mmol, 1 equiv.)
and water (10 ml) were successively added and the solution
extracted with Et2O (4×5 ml). Organic solutions were dried
(MgSO4) and evaporated. Crude 10c (0.3 g) was purified by
FC (CH2Cl2/Et2O 9:1 on 50 g silica gel) to give 10c
(170 mg, 67% yield from 10a).
Same procedure as for 8c with 9b (1.68 g, 4.39 mmol) in
CH2Cl2 (10 ml), NEt3 (0.92 ml, 6.6 ml, 1.5 equiv.) with
ClSO2Me (0.375 ml, 4.8 mmol, 1.1 equiv.) to give 9c
(2.1 g, quant.). 9c was cyclised with the same procedure
as for 10a in EtOH (9 ml) with 2.5 N NaOH (5.3 ml) at
80ЊC for 14 h to give 11a (1.17 g, 73% from 7) after FC
(AcOEt/cyclohexane 3:7 on 60 g silica gel).
10c: yellow oil. [a]D20ˆϪ31 (cˆ1.0, CHCl3). IR (CHCl3):
3400, 2980, 2930, 1675, 1445, 1415, 1375, 1355, 1305,
1
1265, 1230, 1130, 1100, 1090, 1055, 1000, 855. H NMR:
see Table 2. Anal. calcd for C17H23NO5 (321.37): C 63.53, H
7.21, N 4.36; found: C 63.6, H 7.3, N 4.3.
9a: yellowish oil characterised by 1H NMR (CDCl3, 300 K):
4.42 (d, H-C(1)); 3.70 (dd, H-C(2)); 4.38 (dd, H-C(3)); 4.11
(dd, H-C(4)); 3.29 (dq, H-C(5)); 4.04 (br. s, OH, NH2); 3.49,
3.46 (2s, 2 OMe); 1.55, 1.37 (2s, 2 Me); 1.35 (d, Me(6)).
J(1,2)ˆ7.5 Hz, J(2,3)ˆ0.8 Hz, J(3,4)ˆ7.9 Hz, J(4,5)ˆ
1.9 Hz, J(5,Me(6))ˆ6.7 Hz.
9b: yellowish oil characterised by 1H NMR (CDCl3, 300 K):
7.32 (m, 5 H arom.); 5.32 (br. s, NH-C(5)); 5.09, 5.10 (2d,
CH2Ph, Jˆ12.4 Hz); 4.34 (d, H-C(1)); 3.68 (ddd, H-C(2));
4.24 (dd, H-C(3)); 4.08 (dd, H-C(4)); 4.03 (m, H-C(5));
3.44, 3.39 (2s, 2 OMe); 2.36 (d, OH-C(2)); 1.52, 1.37 (2s,
2 Me); 1.28 (d, Me(6)). J(1,2)ˆ6.7 Hz, J(2,OH-2)ˆ4.6 Hz,
J(2,3)ˆ 3.1 Hz, J(3,4)ˆ6.6 Hz, J(4,5)ˆ4.0 Hz, J(5,NH-5)ˆ
7.1 Hz, J(5,Me(6))ˆ6.4 Hz. Rfˆ0.21 (AcOEt/cyclohexane
1:1).
2,5-(Benzyloxycarbonylimino)-3,4-O-isopropylidene-
2,5,6-trideoxy-d-talose (benzyl (2S)-r-2-formyl-t-3,t-4-
isopropylidenedioxy-t-5-methyl-pyrrolidine-1-carboxylate,
(11b)) and 2,5-(benzyloxycarbonylimino)-3,4-O-isopropyl-
idene-2,5,6-trideoxy-d-talitol (benzyl (2S)-r-2-hydroxy-
methyl-t-3,t-4-isopropylidenedioxy-t-5-methyl-pyrrolidine-
1-carboxylate, (11c)). To a stirred solution of 11a (0.85 g,
2.32 mmol) in acetone (9.5 ml) under Ar at 40ЊC was added
Amberlyst-15 (Hϩ) (1.22 g) in six times (four additions of
0.23 g at 0, 3, 4.5, 7 h and two additions of 0.15 g at 11 and
15 h). After 17.5 h the conversion was complete and the
same treatment as for 10b gave crude 11b (0.96 g, quant.)
which was reduced with the same procedure as for 10b in
dry MeOH (3.7 ml) with NaBH4 (90 mg, 2.3 mmol,
1 equiv.) to give after FC (CH2Cl2/Et2O 9:1) 11c (0.58 g,
78% from 11a).
1
9c: yellow oil, characterised by H NMR (CDCl3, 333 K):
1
7.34 (m, 5 H arom.); 5.13 (s, CH2Ph); 4.88 (br d, NH-C(5));
4.51 (d, H-C(1)); 4.99 (dd, H-C(2)); 4.43 (dd, H-C(3)); 4.03
(dd, H-C(4)); 4.14 (ddq, H-C(5)); 3.51, 3.46 (2s, 2 OMe);
2.96 (s, SO2Me); 1.52, 1.38 (2s, 2 Me); 1.21 (d, Me(6)).
J(1,2)ˆ4.6 Hz, J(2,3)ˆ8.8 Hz, J(3,4)ˆ6.6 Hz, J(4,5)ˆ
2.4 Hz, J(5,Me(6))ˆ6.6 Hz, J(5,NH-5)ˆ9.3 Hz. Rfˆ0.33
(AcOEt/cyclohexane 1:1).
11b: yellow-brownish oil characterised by H NMR: see
Table 2. Rfˆ0.25 (CH2Cl2/Et2O 9:1).
11c: yellow oil. [a]D21ˆϪ62 (cˆ1.0, CHCl3). IR (CHCl3):
2980, 2940, 1690, 1455, 1415, 1395, 1355, 1310, 1240,
1
1165, 1140, 1100, 1070, 1030, 870. H NMR: see Table 2.
13C NMR (CDCl3, 333 K): 168.3 (NCO2); 136.7, 128.6,
128.2, 128.1 (Ph); 112.0 (CMe2)); 81.6 (C(3)); 80.1
(C(4)); 67.1 (CH2Ph); 64.8 (C(2)); 63.0 (C(1)); 58.1
(C(5)); 26.2, 25.2 (2 Me); 15.4 (Me(6)). Rfˆ0.08 (CH2Cl2/
Et2O 9:1), Rfˆ0.35 (AcOEt/cyclohexane 7:3). No satisfac-
tory elemental analysis.
11a: yellow oil. [a]D20ˆϪ93 (cˆ1.0, CHCl3). IR (CHCl3):
2990, 2930, 2830, 1685, 1450, 1410, 1385, 1375, 1350, 1320,
1305, 1240, 1190, 1165, 1140, 1110, 1070, 1025, 870, 695.
1H NMR: see Table 2. Rfˆ0.49 (AcOEt/cyclohexane 1:1).
Anal. calcd for C19H27NO6 (365.42): C 62.45, H 7.45, N
3.83; found: C 62.4, H 7.4, N 3.9.
2,5-(Benzyloxycarbonylimino)-2,5,6-trideoxy-d-altritol
(benzyl (2R)-c-3,c-4-dihydroxy-r-2-hydroxymethyl-t-5-
methyl-pyrrolidine-1-carboxylate, (12a)) and 2,5-imino-
2,5,6-trideoxy-d-altritol ((2R,3S,4R,5R)-2-hydroxy-
methyl-5-methyl-pyrrolidine-3,4-diol, (12b)). A solution
of 10c (0.327 g, 1.02 mmol) in EtOH (2 ml) was stirred with
Amberlyst-15 (Hϩ) (40 mg, 40 mg pro mmol acetonide) at
2,5-(Benzyloxycarbonylimino)-3,4-O-isopropylidene-2,
5,6-trideoxy-d-altrose (benzyl (2S)-r-2-formyl-c-3,c-4-isopro-
pylidenedioxy-t-5-methyl-pyrrolidine-1-carboxylate, (10b)).
A solution of 10a (1.03 g, 2.83 mmol) in dry acetone
(12 ml) was stirred at 40ЊC for 1 h with Amberlyst-15

T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
977
80ЊC for 7 h. The catalyst was discarded and washed with
MeOH, the solvents were evaporated to give 12a (0.29 g,
quant.).
with Et2O (4×10 ml)), gave after FC (AcOEt/cyclohexane
7:3) pure 14b (0.49 g, 54% from 10a).
14a can be isolated by evaporation of the isomerisation
A solution of 12a (0.29 g, 1.02 mmol) in EtOH (2 ml) was
hydrogenolysed over 5% Pd/C (21 mg) at 40ЊC for 1 h. The
catalyst was discarded by centrifugation and washed with
EtOH, the solvents were evaporated to give 12b (0.12 g,
80% from 10c after recrystallisation in MeOH/Et2O).
solution as a yellowish oil, characterised by 1H NMR
1
(CDCl3, 336 K): see Table 2. H NMR (CDCl3, 300 K,
two rotamers 50:50): 9.70, 9.63 (2s, CHO(1), two rotamers);
7.35 (m, 5 H arom.); 5.20, 5.15 (2s, CH2Ph, two rotamers);
4.93 (s, H-C(3)); 4.64, 4.51 (2s, H-C(2), two rotamers); 4.36
(d, Jˆ5.7 Hz, H-C(4)); 4.32 (m, H-C(5)); 1.43, 1.31 (2 Me);
1.16, 1.12 (2d, Jˆ7.0 Hz, Me(6), two rotamers). Rfˆ0.29
(CH2Cl2/Et2O 9:1).
1
12a: yellow oil, characterised by H NMR (CDCl3, 298 K,
two rotamers in 70:30 proportions): see Table 2 for the
major rotamer, 7.35 (m, 5 H arom.); 5.05–5.21 (m,
CH2Ph); 4.51 (dd, Jˆ4.8, 8.7 Hz, H-C(3)); 4.26 (dd, Jˆ
3.4, 11.4 Hz, Ha-C(1) maj.); 3.95, 3.79 (2m, Ha-C(1) min.,
Hb-C(1), H-C(2), H-C(4), H-C(5); 1.24, 1.16 (2d, Jˆ6.7 Hz,
Me(6) min. and maj.). Rfˆ0.43 (AcOEt/EtOH 9:1).
14b: yellow oil. [a]D20ˆϩ13 (cˆ1.0, CHCl3). IR (CHCl3):
3430, 2985, 2940, 1685, 1450, 1410, 1375, 1355, 1325,
1
1265, 1235, 1155, 1130, 1100, 1060 1020, 865, 690. H
NMR: see Table 2. 13C NMR (CDCl3, 333 K): 155.6
(NCO2); 136.7, 128.5, 128.1, 127.8, (Ph); 112.0 (CMe2);
85.6 (C(4)); 81.9 (C(3)); 67.3 (CH2Ph); 66.9 (C(2)); 64.2
(C(()); 60.5 (C(5)); 27.4, 25.4 (2 Me); 19.7 (Me(6)).
Rfˆ0.37 (AcOEt/cyclohexane 7:3). Anal. calcd for
C17H23NO5 (321.37): C 63.53, H 7.21, N 4.36; found: C
63.8, H 7.3, N 4.3.
12b: colourless crystals, mpˆ118–120ЊC (MeOH/Et2O).
[a]2D0ˆϩ36 (cˆ0.83, MeOH). IR (KBr): 3390, 3260,
2910, 1440, 1370, 1320, 1105, 1080, 1040, 1020, 950,
880, 810, 765, 685. 1H NMR: see Table 2. 13C NMR
(D2O, 300 K): 65.3 (C(1)); 63.5 (C(2)); 76.6 (C(3)); 83.3
(C(4)); 59.6 (C(5)); 21.8 (Me(6)). Anal. calcd for:
C6H13NO3 (147.17): C 48.96, H 8.90, N 9.52; found: C
48.6, H 8.9, N 9.3.
2,5-(Benzyloxycarbonylimino)-2,5,6-trideoxy-d-allitol
(benzyl (2S)-t-3,t-4-dihydroxy-r-2-hydroxymethyl-c-5-
methyl-pyrrolidine-1-carboxylate, (15a)). Same procedure
as for 12a, starting from 14b (0.40 g, 1.25 mmol) in EtOH
(4 ml) with Amberlyst 15 (Hϩ) (50 mg) at 80ЊC for 18 h.
Purification by FC (AcOEt/cyclohexane 7:3 on 30 g silica
gel) gave pure 15a (0.313 g, 90%).
2,5-(Benzyloxycarbonylimino)-2,5,6-trideoxy-d-talitol
(benzyl (2R)-t-3,t-4-dihydroxy-r-2-hydroxymethyl-t-5-
methyl-pyrrolidine-1-carboxylate, (13a)) and 2,5-imino-
2,5,6-trideoxy-d-talitol ((2R,3R,4S,5R)-2-hydroxy-
methyl-5-methyl-pyrrolidine-3,4-diol, (13b)). Same pro-
cedure as for 12a from 11c (0.317 g, 0.99 mmol) in EtOH
(2 ml) with Amberlyst-15 (Hϩ) (40 mg) for 4 h at 80ЊC to
give 13a (0.257 g, 92%) after FC (AcOEt on 30 g silica gel).
Hydrogenolysis of 13a as for 12a in EtOH (2 ml) over 5%
Pd/C (18 mg) for 1 h at 40ЊC gave 13b (0.125 g, 93%) after
evaporation of the solvent.
15a: yellow oil. [a]D20ˆϩ9 (cˆ1.0, CHCl3). IR (CHCl3):
1
3385, 2940, 1670, 1450, 1415, 1355, 1145, 1085, 690. H
NMR: see Table 2. 13C NMR (CDCl3, 336 K): 156.7
(NCO2); 136.4, 128.5, 128.1, 127.8 (Ph); 76.2 (C(4)); 72.7
(C(3)); 67.4 (CH2Ph); 65.2 (C(2)); 63.7 (C(1)); 60.1 (C(5));
18.8 (Me(6)). Rfˆ0.07 (AcOEt/cyclohexane 7:3). Anal.
calcd for C14H19NO5 (281.31): C 59.77, H 6.81, N 4.98;
found: C 59.8, H 6.5, N 4.8.
1
13a: colourless oil, characterised by H NMR: see Table 2.
Rfˆ0.05 (AcOEt/cyclohexane 7:3), Rfˆ0.34 (AcOEt/EtOH 9:1).
2,5-Imino-2,5,6-trideoxy-d-allitol ((2S,3S,4R,5R)-2-hydroxy-
methyl-5-methyl-pyrrolidine-3,4-diol, (15b)). Hydro-
genolysis of 15a (0.20 g, 0.71 mmol) as for 12b in EtOH
(2 ml) over 5% Pd/C (14 mg) for 3 h at 40ЊC gave 15b
(0.102 g, 97%).
13b: colourless oil. [a]1D9ˆϩ46 (cˆ1.0, CH3OH). IR (KBr):
3380, 2900, 1400, 1370, 1335, 1230, 1195, 1155, 1110,
1075, 1060, 1025, 1000, 940, 875, 800. 1H NMR: see
Table 2. 13C NMR (CD3OD, 300 K): 63.8 (C(1)); 64.3
(C(2)); 75.9 (C(3)); 75.4 (C(4)); 56.4 (C(5)); 14.8 (Me(6)).
Anal. calcd for: C6H13NO3 (147.17): C 48.96, H 8.90, N
9.52; found: C 48.9, H 8.8, N 9.3.
1
15b: colourless oil. [a]2D0ˆϪ2 (cˆ1.0, MeOH). H NMR:
see Table 2. 13C NMR (D2O, 300 K): 65.2 (C(1)); 62.1
(C(2)); 72.5 (C(3)); 77.3 (C(4)); 58.2 (C(5)); 17.3 (Me(6)).
Anal. calcd for C6H13NO3 (147.17): C 48.96, H 8.90, N
9.52; found: C 48.7, H 8.9, N 9.4.
2,5-(Benzyloxycarbonylimino)-3,4-O-isopropylidene-
2,5,6-trideoxy-d-allose (benzyl (2R)-r-2-formyl-t-3,t-4-
isopropylidenedioxy-c-5-methyl-pyrrolidine-1-carboxylate,
(14a)), 2,5-(benzyloxycarbonylimino)-3,4-O-isopropylidene-
2,5,6-trideoxy-d-allitol (benzyl (2S)-r-2-hydroxymethyl-
t-3,t-4-isopropylidenedioxy-c-5-methyl-pyrrolidine-1-
carboxylate, (14b)). A solution of crude 10b (0.876 g,
2.75 mmol) in MeOH (10 ml) was stirred with Na2CO3
(0.29 g, 2.74 mmol, 1 equiv.) at rt under Ar for 1 h to give
a solution of 14a which was reduced at once by adding
NaBH4 (0.207 g, 5.49 mmol, 2 equiv.) and stirring for
15 min. Same treatment as for 10c (addition of acetone
(5 ml), aq. 1N HCl (2.7 ml), water (30 ml) and extraction
Enzyme inhibitions
Glycosidase activities were determined at 25ЊC at the
optimal pH of each enzyme19 with the corresponding
p-nitrophenyl glycopyranoside as substrate against a-d-
glucosidase (EC 3.2.1.20) from baker’s yeast (9 units per
mg of protein, Kmˆ0.3 mM, pHˆ6.8), b-d-glucosidase (EC
3.2.1.21) from almonds (20–40 units per mg of protein,
Kmˆ2 mM, pHˆ5.0), a-d-mannosidase (EC 3.2.1.24)
from Jack beans (ca. 20 units per mg of proteins,

978
T. Sifferlen et al. / Tetrahedron 56 (2000) 971–978
6. Liu, K. K.-C.; Kajimoto, T.; Cheng, L.; Zhong, Z.; Ichikawa,
Y.; Wong, Ch.-H. J. Org. Chem. 1991, 56, 6280–6289.
7. Wong, Ch.-H.; Dumas, D. P.; Ishikawa, Y.; Koseki, K.;
Danishefsky, S. J.; Weston, Br. W.; Lowe, J. B. J. Am. Chem.
Soc. 1992, 114, 7321–7322; Ishikawa, Y.; Lin, Y.-Ch.; Dumas,
D. P.; Shen, G.-J.; Garcia-Junceda, E.; Williams, M. A.; Bayer,
R.; Ketcham, C.; Walker, L. E.; Paulson, J. C.; Wong, Ch.-H. J. Am.
Chem. Soc. 1992, 114, 9283–9298; Qiao, L.; Murray, Br. W.;
Shimazaki, M.; Schultz, J.; Wong, Ch.-H. J. Am. Chem. Soc.
1996, 118, 7653–7662.
8. Molyneux, R. J.; Pan, Y. T.; Tropea, J. E.; Elbein, A. D.;
Lawyer, C. H.; Hughes, D. J.; Fleet, G. W. J. J. Nat. Prod. 1993,
56, 1356–1364.
9. Defoin, A.; Sarazin, H.; Streith, J. Tetrahedron 1997, 53,
13769–13782; 13783–13796.
Kmˆ2 mM, pHˆ4.5), a-l-fucosidase (EC 3.2.1.51) from
bovine kidney (5–15 units per mg, Kmˆ0.15 mM,
pHˆ6.0) and a-d-galactosidase (EC 3.2.1.22) from green
coffee beans (10 units per mg, Kmˆ0.3 mM, pHˆ6.0).
Glycosidases and corresponding p-nitrophenyl glyco-
pyranosides were obtained from Sigma Chemical Co. The
release of p-nitrophenol was measured continuously at
400 nm to determine initial velocities.20 All kinetics were
started by enzyme addition in a 1 ml assay medium using
substrate concentrations around the Km value of each
enzyme. Ki values were determined for the most potent
inhibitors using the Dixon graphical method,21 IC50 values
were determined for weak inhibitions (at a substrate concen-
tration equal to Km value) and correspond to the inhibitor
concentration required for 50% inhibition of the enzyme in
our experimental conditions.
ˆ
10. Defoin, A.; Sifferlen, Th.; Streith, J.; Dosbaa, I.; Foglietti,
M.-J. Tetrahedron: Asymmetry 1997, 8, 363–366.
ˇ
11. Tschamber, Th.; Waespe-Sarcevic, N.; Tamm, Ch. Helv.
Chim. Acta 1986, 69, 621–625; Defoin, A.; Pires, J.; Streith, J.
Helv. Chim. Acta 1991, 74, 1653–1670.
Acknowledgements
12. Coppola, G. M. Synthesis 1984, 1021–1023.
13. According to the last step of Wong’s synthesis,4 the isomer he
synthesised probably had the all-cis configuration.
14. Lustig, E.; Benson, W. R.; Duy, N. J. Org. Chem. 1967, 32,
851–852.
The support of the Centre National de la Recherche Scien-
tifique (UPRES-A 7015) is gratefully acknowledged. We
`
also wish to thank the Ministere de l’Enseignement et de
la Recherche for a Ph.D. grant to Th. Sifferlen.
¨
15. Wehner, V.; Jager, V. Angew. Chem., Int. Ed. Engl. 1990, 29,
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