Stereocontrolled preparation of 2-,3- and 4-isothiocyanato aldopyranose derivatives

Article abstract of DOI:10.1016/S0957-4166(00)00212-3

The regio- and stereocontrolled introduction of an isothiocyanato group into the positions 2, 3 and 4 of glycopyranose derivatives starting from glycosides, glycosylamines, and aminosugars is reported. Isothiocyanato sugars with D-gluco, D-allo and D-mann

Full text of DOI:10.1016/S0957-4166(00)00212-3

Tetrahedron: Asymmetry 11 (2000) 2471±2482
Stereocontrolled preparation of 2-,3- and 4-isothiocyanato
aldopyranose derivatives
Jose Fuentes,* David Olano, Consolacion Gasch and M. Angeles Pradera
Â
Departamento de Quõmica Organica, Facultad de Quõmica, Universidad de Sevilla, Apartado 553,
Â
Â
E-41071 Sevilla, Spain
Received 13 April 2000; accepted 25 May 2000
Abstract
The regio- and stereocontrolled introduction of an isothiocyanato group into the positions 2, 3 and 4 of
glycopyranose derivatives starting from glycosides, glycosylamines, and aminosugars is reported. Iso-
thiocyanato sugars with d-gluco, d-allo and d-manno con®gurations have been prepared. # 2000 Elsevier
Science Ltd. All rights reserved.
1. Introduction
Of the sugar isothiocyanates, the glycosyl derivatives are the most well-known compounds, and
have been widely used in di€erent syntheses of glycoconjugates, whose sugar moiety is a mono-
saccharide to trisaccharide glycosyl radical.1 In recent years, various synthetic methods for both
pyranoid1c,2 and furanoid3 glycosyl isothiocyanates have been reported. However, the data on the
introduction of an NCS group onto a non-glycosydic position of a sugar,4 onto a polyol chain,5
or onto the secondary positions of sugar moieties of C-nucleosides6 are limited, in spite of the
interest of deoxy-isothiocyanato derivatives in the preparation of guanidinosugars,5 macro-
cycles,7 several glycomimetics,1c,8 and pseudonucleosides.4c Frequently, there are problems of
formation of mixtures of diastereomers,1c or of reactions between the NCS group and a neigh-
bouring hydroxyl group6c in the described synthetic methods for deoxy-isothiocyanato sugars.
In this paper we report on the stereocontrolled introduction of an isothiocyanato group into
di€erent secondary positions of d-glycopyranose rings. We have chosen, as carbohydrate deriv-
atives, glycosides, and glycosylamines, potentially useful for glycoconjugates and macrocycles
syntheses, and as con®gurations, d-gluco, d-allo and d-manno. The stereocontrol is based mainly
on the use of SN2 reactions.
* Corresponding author. E-mail: jfuentes@cica.es
0957-4166/00/$ - see front matter # 2000 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(00)00212-3

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2. Results and discussion
For the introduction of the NCS group onto the position 4 of a d-glucopyranose ring, we have
started from the a-methyl-d-galactopyranoside derivative 1,9 and from the partially O-benzoylated-
b-d-galactopyranosylamine derivative 810 (Scheme 1). Conventional O-benzoylation with benzoyl
chloride of 1 gave the di-O-benzoylderivative 2. The regioselective ring opening of the 4,6-acetal
ring of 2 with sodium cyanoborohydride in DMF and tri¯uoroacetic acid produced the partially
O-protected d-galactoglycoside 3. The chemical shifts for the resonances of H-2 and H-3 in
compounds 2 and 3 were in agreement with the presence of the benzoyl groups (see Table 1 and
Experimental). The IR spectrum of 3 showed the OH band at 3300 cm^1, and the corresponding
1H NMR spectrum had the signal for H-4 at 4.45 ppm (CHOH), and the value for J4,5 was
roughly 0 Hz, as is described11 for related d-galactopyranosyl derivatives.
Scheme 1.
Treatment of the d-galactopyranosyl compounds 3 and 8, with the hydroxyl group on C-4
being free, with mesyl chloride gave, in good yield, the corresponding 4-methanesulphonyl esters
4 and 9, which by reaction with sodium azide in hexamethylphosphoramide (HMPT) at 60±70ꢀC
produced the 4-azido-4-deoxyglucopyranosyl compounds 5 and 10 in high yield. No appreciable
elimination products were observed in the formation of 5 and 10, nor were compounds coming
from the internal nucleophilic attack of the NH (enamino group) on C-411 formed in the case of
10. Catalytic hydrogenation of 5 and 10 produced the 4-aminosugars 6 and 11, which by reaction
with thiophosgene in a basic medium gave the 4-deoxy-4-isothiocyanatoglucoside 7 or glucosylen-
amine 12, respectively.
The structures of compounds 4±7 and 9±12 were supported by analytical and spectroscopic
data. The chemical shifts for the resonances of H-4 in compounds 4 and 9 showed a down®eld

J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
2473
Table 1
Relevant NMR data for compounds 2±7, 9±12, 14, 16, 18, 21, 22 and 24 in CDCl3
shift of ꢁ1 ppm when they were compared with the same signal for 3 and 8, supporting the for-
mation of the sulphonic ester. Compounds 5 and 10 had the IR absorption at ꢁ2100 cm^1 for the
azido group, and the vicinal coupling constants values J3,4 and J4,5, roughly 10 Hz, supported
the formation of the d-glucopyranosyl ring. The presence of the isothiocyanato group in 7 and 12
was based on the IR band at ꢁ2041 cm^1, and on the NMR resonances at ꢁ140 (NCS), ꢁ57 (C-4),
and 4.30 ppm (H-4), which are characteristic1c of the isothiocyanato-sugars.
A suitable starting material to prepare 3-deoxy-3-isothiocyanato-d-allopyranosylamines is the
N-protected d-glucopyranosylamine 1310 (Scheme 2). The regioselective acetylation of 13 with
acetic anhydride and pyridine, using a molar ratio 1:3 (13: Ac2O) at ^20ꢀC, produced a mixture of
acetylated products, whose NMR spectra showed that the 2,4,6-tri-O-acetyl 14 and 2,3,6-tri-O-
acetyl derivatives are the preponderant compounds. After the mixture was boiled in ethyl ether,
transacylation took place and 14 was obtained as sole crystalline product. Its IR spectra had the
Scheme 2. Reagents and conditions. (i) Ac2O/Py, ^20ꢀC; (ii) Tf2O/Py, ^15ꢀC; (iii) NaN3, rt; (iv) H2/Pd/C, rt; (v)
Cl2CS, rt

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J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
OH band at 3420 cm^1, and the resonance for H-3 appeared at 3.81 ppm, showing a coupling
between H-3 and the hydroxyl group of 5.0 Hz.
Treatment of 14 with tri¯uoromethanesulphonic anhydride gave the 3-O-trifyl-d-glucopyr-
anosylamine derivative 15. The C-3 con®guration of 15 was inverted by reaction with sodium
azide, producing the 3-azido-3-deoxy-d-allopyranosylamine 16. Catalytic [Pd(OH)2] hydrogenation
of the latter gave the amino derivative 17. This was directly reacted with thiophosgene to produce
the 3-deoxy-3-isothiocyanato-d-allopyranosylamine derivative 18.
The spectroscopic data of 16 supported both the introduction of the azido group (IR absortion
at 2130 cm^1, and H-3 and C-3 resonances at 4.46 and 60.7 ppm, respectively) and the d-allo
con®guration (J2,3=J3,4=3.2 Hz). In the case of compound 18, the presence of the NCS group
was con®rmed by the 13C resonances at 141.7 (NCS) and 58.1 ppm (C-3), and by the IR band at
2047 cm^1 (NCS).
As the 2-amino-2-deoxy monosaccharides are the most readily available aminosugars, to
introduce an isothiocyanato group into the position 2 of the d-mannopyranose ring we started
from 2-amino-2-deoxy-d-mannose hydrochloride 19 (Scheme 3). The reaction of this aminosugar
with diethyl ethoxymethylene malonate produced the N-protected d-mannosamine 20, with an
a:b ratio of 3:1. Acetylation of 20 with acetic anhydride gave a mixture of the tetra-O-acetyl-
derivatives anomers 21 and 22, the a:b anomers ratio being 4:1. This mixture was resolved by
column chromatography to obtain the a (21, 41%) and b (22, 11%) anomers as pure products.
The following reactions were performed on the major a anomer. The NMR spectra of com-
pounds 20±22 contained the characteristic1b signals of the enamino group (see Experimental); the
J1,2 value for the a-anomer 21 (2.0 Hz) and for the b-anomer 22 (1.3 Hz) were very close to that
described12 for related pairs of anomers with d-manno con®guration. In all the compounds having
the enamino group (9, 10, 12, 14, 16, 18, 21 and 22), the ꢀ values for NH (9.18±9.62 ppm), for a
CO2Et group (167.4±168.4, CˆO chelated) and the IR absorptions at 1650±1670 cm^1 (CˆO
chelated) were indicative13 of the hydrogen bond shown in Fig. 1. The J1,NH (J2,NH for 21 and 22)
value of these compounds was in the range 8.9±9.9 Hz, indicating trans relationship between the
corresponding protons (Fig. 1).
Scheme 3. Reagents and conditions. (i) EtOCHˆC(CO2Et)2, Na2CO3, rt; (ii) Ac2O/Py, ^20ꢀC; (iii) Cl2/CH2Cl2, 0ꢀC;
(iv) Cl2CS, rt

J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
2475
Figure 1. Conformation of the CH±NH bond
The N-deprotection of 21 with chlorine in dichloromethane yielded the O-acetylated amino-
sugar 23, which by reaction with thiophosgene produced the 2-deoxy-2-isothiocyanato d-manno
derivative 24 with a 75% overall yield from 21. The NCS group of 24 was evident from the IR
absorption at 2062 cm^1, and from the resonances of NCS (140.2 ppm), C-2 (57.5 ppm), and H-2
(4.26 ppm). All the vicinal coupling constant values of the mannopyranose ring were indicative12
that, in solution in chloroform, the 4C1 conformation is little distorted, in spite of the presence of
the polar NCS group in axial disposition on C-2.
3. Conclusion
For the regio- and stereocontrolled introduction of an isothiocyanato group into secondary
positions of glycopyranose rings, the reaction of O-protected aminosugar derivatives with thio-
phosgene is a useful method. In the case of the position 2, it is possible to start from a commercial
product, whereas in the cases of the positions 3 and 4 the amino group is introduced via sulphonyl-
oxy and azido derivatives using SN2 reactions. The method is potentially useful for the preparation
of diisothiocyanato derivatives when an additional enamino group exists (12), as this group is a
latent NCS group (sequence 20±24).
4. Experimental
4.1. General methods
Melting points are uncorrected. Optical rotations were measured for solutions in dichloro-
1
methane. FTIR spectra were recorded for KBr discs or thin ®lm. H NMR spectra (500 or 300
MHz) were obtained for solutions in CDCl3 or MeOH-d4. Assignments were con®rmed by
homonuclear 2D COSY correlated experiments. 13C NMR spectra were recorded at 125.7 or 75.4
MHz. Heteronuclear 2D correlated spectra were obtained in order to assist in carbon resonance
assignments. Mass spectra (EI and FAB) were recorded with a Kratos MS-80RFA and Micro-
mass AutoSpecQ instruments with a resolution of 1000 or 10 000(10% valley de®nition). For the
FAB spectra, ions were produced by a beam of xenon atoms (6±7 KeV), using 3-nitrobenzyl
alcohol and thioglycerol as matrix and NaI as salt. TLC was performed on silica gel HF254, with
detection by UV light or charring with H2SO4. Silica gel 60 (Merck, 70±230 and 230±400 mesh)
was used for preparative chromatography.

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J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
4.2. Methyl 2,3-di-O-benzoyl-4,6-O-(4-methoxybenzylidene)-ꢁ-d-galactopyranoside 2
To a stirred solution of methyl 4,6-O-(4-methoxybenzylidene)-a-d-galactopyranoside 19 (0.719
g, 2.3 mmol) in pyridine (3.7 ml) at 0ꢀC benzoyl chloride (0.92 ml, 7.1 mmol) in pyridine (3.3. ml)
was added dropwise. The mixture was stirred for 12 h at rt and then poured into ice-water (500
ml) and extracted with CH2Cl2. The extracts were washed with H2SO4 (2N), aq. NaHCO3 (satu-
rated) and water, dried (MgSO4), and concentrated. Column chromatography (2:1 Et2O:petroleum
ether) on silica gel gave 2 (1.140 g, 95%) as an amorphous solid. [ꢁ]2D7 +209.6 (c 1.8); FABMS: m/z
1
543 [M+Na]+; H NMR (300 MHz, CDCl3): ꢀ 8.03±6.87 (m, 14H, Ar), 5.78 (m, 2H, H-2, H-3),
5.53 (s, 1H, CH-Ar), 5.29 (d, 1H, J1,2=1.6, H-1), 4.64 (d, 1H, J3,4=1.2, H-4), 4.34 (dd, 1H,
J5,6a=1.6, J6a,6b=12.5, H-6a), 4.13 (dd, 1H, J5,6b=1.7, H-6b), 3.89 (m, 1H, H-5), 3.81 (s, 3H,
CH3O-Ar), and 3.47 (s, 3H, CH3O) ppm; 13C NMR (125.7 MHz): ꢀ 166.0, 165.8 (2 CO), 159.8±
113.3 (18 C, Ar), 100.5 (CH), 97.9 (C-1), 74.1 (C-4), 69.0 (2 C, C-2, C-3), 68.7 (C-6), 62.0 (C-5),
55.5 and 55.1 (2 CH3O) ppm. Anal. calcd for C29H28O9: C, 66.91; H, 5.42. Found: C, 66.83;
H, 5.58.
4.3. Methyl 2,3-di-O-benzoyl-6-O-(4-methoxybenzyl)-ꢁ-d-galactopyranoside 3
To a solution of 2 (0.957 g, 1.84 mmol) and Na(CN)BH3 (0.578 g, 9.2 mmol) in DMF (17 ml)
over 4 A molecular sieves at 0ꢀC, a solution of 0.1% F3CCOOH in DMF (14 ml) was added
dropwise. After 7 h at rt the reaction mixture was ®ltered through Celite, poured into ice-aq.
NaHCO3 (saturated) and extracted with CH2Cl2. The organic layer was washed with cool aq.
NaHCO3 (saturated), dried (MgSO4) and concentrated. The residue was puri®ed by chromato-
graphy (CH2Cl2) to yield 3 (0.637 g, 67%) as an amorphous solid. [ꢁ]2D7 +103.3 (c 1.2); FABMS:
1
m/z 545 [M+Na]+; IR ꢂmax 3300 cm^1 (HO); H NMR (500 MHz, CDCl3); ꢀ 8.03±6.87 (m, 14H,
Ar), 5.72±5.66 (m, 2H, H-2, H-3), 5.22 (d, 1H, J1,2=3.2, H-1), 4.57, 4.52 (each d, each 1H,
JH,H=11.6, CH2), 4.45 (bs, 1H, H-4), 4.13 (m, 1H, H-5), 3.85±3.78 (m, 2H, H-6a, H-6b), 3.80 (s,
3H, CH3O-Ar) and 3.43 (s, 3H, CH3O) ppm; 13C NMR: ꢀ 165.9, 165.7 (2 CO), 159.3±113.8 (18 C,
Ar), 97.6 (C-1), 73.4 (CH2) 71.0 (C-3), 69.7 (C-6), 69.2 (C-4), 69.0 (C-2), 68.1 (C-5), 55.4 and 55.1
(2 CH3O) ppm. Anal calcd for C29H30O9: C, 66.66; H, 5.79. Found: C, 66.29; H, 6.21.
4.4. Procedure for mesylation of 3 and 8
To a stirred solution of 3 (0.48 g, 0.92 mmol) or 8 (0.2 g, 0.3 mmol) in pyridine (x ml) at 0ꢀC
mesyl chloride (y ml) was gradually added. The mixture was kept for t h at rt, then poured into
ice-water and extracted with CH2Cl2. The combined organic layers were washed with H2SO4
(2N), aq. NaHCO3 (saturated) and water, dried (MgSO4) and concentrated. The residue was
puri®ed as described.
4.4.1. Methyl 2,3-di-O-benzoyl-4-O-mesyl-6-O-(4-methoxybenzyl)-ꢁ-d-galactopyranoside 4
x=27 ml; y=0.2 ml; t=13 h. Column chromatography (CH2Cl2) gave 4 (0.49 g, 90%) as an
amorphous solid. [ꢁ]2D7 +118.5 (c 1.0); FABMS: m/z 623 [M+Na]+; 1H NMR (500 MHz, CDCl3): ꢀ
8.03±6.88 (m, 14H, Ar), 5.78 (dd, 1H, J2,3=10.9, J3,4=3.0, H-3), 5.59 (dd, 1H, J1,2=3.6, H-2),
5.45 (d, 1H, H-4), 5.16 (d, 1H, H-1), 4.55, 4.49 (each d, each 1H, JH,H=11.1, CH2), 4.31 (m, 1H, H-5),
3.81 (s, 3H, CH3O-Ar), 3.70±3.68 (m, 2H, H-6a, H-6b), 3.44 (s, 3H, CH3O) and 3.02 (s, 3H,
Ms) ppm; 13C NMR (125.7 MHz): ꢀ 165.8, 165.5 (2 CO), 159.2±113.7 (18 C, Ar), 97.3 (C-1),

J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
2477
76.6 (C-4), 73.2 (CH2), 68.4 (C-2), 68.2 (C-3), 67.2 (C-6), 67.0 (C-5), 55.6, 55.1 (2 CH3O) and 23.6
(Ms) ppm. Anal. calcd for C30H32O11S: C, 59.99; H, 5.37; S, 5.34. Found: C, 60.12; H, 5.08; S,
5.10.
4.4.2. 2,3,6-Tri-O-benzoyl-4-O-mesyl-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-galactopyranosylamine 9
x=5 ml; y=0.07 ml; t=14 h. Column chromatography (1:1 AcOEt:petroleum ether) gave 9
(0.20 g, 88%) as an amorphous solid. [ꢁ]2D6 +1.8 (c 1.1); FABMS: m/z 762 [M+Na]+; IR ꢂmax 1663
1
cm^1 (CˆO chelated); H NMR (500 MHz, CDCl3): ꢀ 9.46 (dd, 1H, JNH,HCˆ=13.1, JNH,1=8.9,
NH), 8.07±7.35 (m, 15H, Ar), 7.98 (d, 1H, HCˆ), 5.78 (dd, 1H, J1,2 8.9, J2,3=10.4, H-2), 5.59
(dd, 1H, J3,4=3.1, H-3), 5.49 (dd, 1H, J4,5=0.6, H-4), 4.82 (t, 1H, H-1), 4.71 (dd, 1H, J5,6a=6.0,
J6a,6b=11.3, H-6a), 4.43 (dd, 1H, J5,6b=7.5, H-6b), 4.35 (m, 1H, H-5), 4.28 (m, 2H, CH2CH3),
4.15 (q, 2H, JH,H=7.1, CH2CH3), 3.14 (s, 3H, Ms), 1.33 and 1.25 (t, 6H, 2 CH2CH3) ppm; 13C
NMR (125.7 MHz): ꢀ 167.5, 165.8, 165.4, 165.2, 165.1 (5 CO), 157.0 (HCˆ), 133.6±128.1 (18 C,
Ar), 95.0 (Cˆ), 87.5 (C-1), 74.2 (C-4), 72.2 (C-5), 71.0 (C-3), 68.3 (C-2), 61.2 (C-6), 60.2, 59.9 (2
CH2CH3), 38.8 (Ms) and 14.1 (2 C, 2 CH2CH3) ppm. Anal. calcd for C36H37O14NS: C, 58.45; H,
5.04; N, 1.89; S, 4.33. Found: C, 58.49; H, 5.29; N, 1.97; S, 4.46.
4.5. Procedure for the displacement of MsO group with sodium azide (5,10)
To a stirred solution of the corresponding sulphonyloxysugar 4, 9 (m g) in HMPT (x ml),
sodium azide (y g) was added. The mixture was kept for t h at TꢀC, then poured into ice-water
and extracted with AcOEt. The combined organic layers were washed with water, dried (MgSO4)
and concentrated. The residue was puri®ed by column chromatography.
4.5.1. Methyl 4-azido-2,3-di-O-benzoyl-4-deoxy-6-O-(4-methoxybenzyl)-ꢁ-d-glucopyranoside 5
m=0.375 g, 0.625 mmol; x=5.5 ml; y=0.203 g, 3.12 mmol; t=13 h; T=60ꢀC. Column chrom-
atography (1:4 AcOEt:petroleum ether) gave 5 (0.300 g, 93%) as an amorphous solid. [ꢁ]D26
+177.8 (c 0.7); FABMS: m/z 570 [M+Na]+; IR ꢂmax 2108 cm^1 (N3); 1H NMR (300 MHz, CDCl3):
ꢀ 8.03±6.91 (m, 14H, Ar), 5.91 (m, 1H, H-3), 5.21±5.16 (m, 2H, H-1, H-2), 4.68, 4.55 (each d, each
1H, JH,H=11.6, CH2), 4.04 (t, 1H, J3,4=J4,5=10.0, H-4), 3.93±3.79 (m, 3H, H-5, H-6a, H-6b),
3.82 (s, 3H, CH3O-Ar) and 3.41 ppm (s, 3H, CH3O-C1); 13C NMR (125.7 MHz): ꢀ 165.7, 165.5 (2
CO), 159.3±113.8 (18 C, Ar), 97.1 (C-1), 73.3 (CH2), 71.9 (C-2), 70.9 (C-3), 69.2 (C-5), 67.9 (C-6),
60.3 (C-4), 55.5 and 55.2 (2 CH3O) ppm. Anal calcd for C29H29O8N3: C, 63.61; H, 5.34; N, 7.67.
Found: C, 63.38; H, 5.37; N, 7.40.
4.5.2. 4-Azido-2,3,6-tri-O-benzoyl-4-deoxy-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-glucopyranosylamine
10
m=0.1 g, 0.135 mmol; x =1.2 ml; y=0.044 g, 0.68 mmol; t=12 h; T=70ꢀC. Column chromato-
graphy (7:1 toluene:AcOEt) gave 10 (0.086 g, 92%) as an amorphous solid. [ꢁ]2D0 +6.4 (c 0.6);
1
FABMS: m/z 709 [M+Na]+; IR ꢂmax 2112 (N3) and 1660 cm^1 (CˆO chelated); H NMR (300
MHz, CDCl3): ꢀ 9.31 (dd, 1H, JNH,1=9.5, JNH,CHˆ=13.1, NH), 8.06±7.19 (m, 15H, Ar), 7.87 (d,
1H, HCˆ), 5.70 (t, 1H, J2,3=J3,4=9.5, H-3), 5.38 (t, 1H, J1,2=9.5, H-2), 4.70 (t, 1H, H-1), 4.64
(dd, 1H, J5,6a=2.3, J6a,6b=12.3, H-6a), 4.58 (dd, 1H, J5,6b=3.8, H-6b), 4.18, 4.06 (each q, each
2H, JH,H=7.1, 2 CH2CH3), 3.89 (t, 1H, J4,5=9.5, H-4), 3.78 (ddd, 1H, H-5), 1.23 and 1.16 (each
t, each 3H, 2 CH2CH3) ppm; 13C NMR (75.4 MHz): ꢀ 167.4, 166.0, 165.4, 165.2 (5 C, 5 CO),
157.1 (CHˆ), 133.6±128.1 (18 C, Ar), 95.0 (Cˆ), 87.4 (C-1), 74.4 (C-5), 73.4 (C-3), 71.1 (C-2), 62.9

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(C-6), 60.5 (C-4), 60.2, 60.0 (2 CH2CH3), 14.2 and 14.1 (2 CH2CH3) ppm. Anal. calcd for
C35H34O11N4: C, 61.22; H, 4.99; N, 8.16. Found: C, 61.00; H, 4.86; N, 7.86.
4.6. Procedure for the reduction of the azido group 6,11
The corresponding azidosugar 5, 10 (m g) was dissolved in distilled MeOH (x ml) and hydrog-
enated in the presence of palladium-on-charcoal (y g) for t h at rt and ꢁ1 atm. The catalyst was
®ltered o€ through a Celite pad, and washed with methanol. The ®ltrate and washings were
combined and evaporated to give a syrup which was used without puri®cation in the next step.
4.6.1. Methyl 4-amino-2,3-di-O-benzoyl-4-deoxy-6-O-(4-methoxybenzyl)-ꢁ-d-glucopyranoside 6
m=0.224 g, 0.44 mmol; x=5 ml; y=0.022 g; t=6 h. TLC (1:6) AcOEt:petroleum ether;
FABMS: m/z 544 [M+Na]+.
4.6.2. 4-Amino-2,3,6-tri-O-benzoyl-4-deoxy-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-glucopyranosyl-
amine 11
m=0.2 g, 0.29 mmol; x=5 ml; y=0.02 g; t=10 h. TLC (2:1) AcOEt:petroleum ether; FABMS:
m/z 683 [M+Na]+.
4.7. General method for isothiocyanato derivatives 7, 12
To a heterogeneous mixture of the corresponding glycopyranosylamine (6, 11, x g), dichloro-
methane (y ml), calcium carbonate (z g), and water (y ml), thiophosgene (k ml) was added. The
mixture was vigorously stirred for t h and then ®ltered. The organic layer was washed with water,
dried (MgSO4), concentrated and the residue was puri®ed as indicated. The following compounds
were prepared in this manner.
4.7.1. Methyl 2,3-di-O-benzoyl-4-deoxy-4-isothiocyanato-6-O-(4-methoxybenzyl)-ꢁ-d-glucopyrano-
side 7
x=0.213 g, 0.41 mmol; y=6.5 ml; z=0.16 g, 1.64 mmol; k=0.08 ml, 0.82 mmol; t=6 h. TLC
(1:2) AcOEt:petroleum ether (0.121 g, 51% from 6); [ꢁ]2D7 +116.8 (c 1.0); FABMS: m/z 586
[M+Na]+; IR ꢂmax 2043 cm^1 (NCS); 1H NMR (500 MHz, CDCl3): ꢀ 8.01±6.92 (m, 14H, Ar), 5.98
(t, 1H, J2,3=J3,4=10.1, H-3), 5.17 (d, 1H, J1,2=3.6, H-1), 5.13 (dd, 1H, H-2), 4.65, 4.54 (each d,
each 1H, JH,H=11.7, HCH, HCH), 4.32 (t, 1H, J4,5=10.1, H-4), 4.01 (ddd, 1H, J5,6a=3.0,
J5,6b=2.0, H-5), 3.82 (s, 3H, CH3O-Ar), 3.79 (dd, 1H, J6a,6b=11.2, H-6a), 3.75 (dd, 1H, H-6b)
and 3.42 (s, 3H, CH3O) ppm; 13C NMR (125.7 MHz): ꢀ 165.6, 165.2 (2 CO), 159.3±113.7 (18 C,
Ar), 138.1 (NCS), 97.1 (C-1), 73.3 (CH2), 71.4 (C-2), 70.3 (C-3), 69.3 (C-5), 67.6 (C-6), 56.5 (C-4),
55.5 and 55.1 (2 CH3O) ppm. Anal. calcd for C30H29O8NS: C, 63.93; H, 5.19; N, 2.48; S, 5.69.
Found: C, 63.74; H, 4.96; N, 2.58; S, 6.21.
4.7.2. 2,3,6-Tri-O-benzoyl-4-deoxy-N-(2,2-diethoxycarbonylvinyl)-4-isothiocyanato-ꢃ-d-gluco-
pyranosylamine 12
x=0.192 g, 0.29 mmol; y=1.4 ml; z=0.084 g, 0.848 mmol; k=0.042 ml, 0.424 mmol; t=5 h.
TLC (1:1) ether:petroleum ether (0.111 g, 55% from 11); [ꢁ]2D7 +6.9 (c 0.5); FABMS: m/z 725
1
[M+Na]+; IR ꢂmax 2041 (NCS), and 1651 cm^1 (CˆO chelated); H NMR (500 MHz, CDCl3): ꢀ
9.39 (dd, 1H, JNH,1=9.0, JNH,CHˆ=13.0, NH), 8.12±7.37 (m, 15H, Ar), 7.88 (d, 1H, HCˆ), 5.87

J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
2479
(t, 1H, J2,3=J3,4=9.5, H-3), 5.45 (t, 1H, J1,2=9.5, H-2), 4.81 (t, 1H, H-1), 4.73 (dd, 1H, J5,6a=2.5,
J6a,6b=12.4, H-6a), 4.64 (dd, 1H, J5,6b=4.1, H-6b), 4.27±4.24 (m, 3H, H-4, CH2CH3), 4.14 (q,
2H, JH,H=7.1, CH2CH3), 3.99 (ddd, 1H, J4,5=10.1, H-5), 1.31 and 1.24 (each t, each 3H, 2
CH2CH3) ppm; 13C NMR (125.7 MHz): ꢀ 167.5, 166.0, 165.5, 165.4, 165.3 (5 CO), 157.2 (CHˆ),
141.3 (NCS), 133.7±128.5 (18 C, Ar), 95.1 (C=), 87.2 (C-1), 74.6 (C-5), 72.9 (C-3), 70.9 (C-2),
62.9 (C-6), 60.4, 60.1 (2 CH2CH3), 57.1 (C-4) and 14.4 (2 C, 2 CH2CH3) ppm. Anal. calcd for
C36H34O11N2S: C, 61.53; H, 4.88; N, 3.99; S, 4.56. Found: C, 61.42; H, 4.75; N, 4.14; S, 4.84.
4.8. 2,4,6-Tri-O-acetyl-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-glucopyranosylamine 14
To a stirred solution of N-(2,2-diethoxycarbonylvinyl)-b-d-glucopyranosylamine (3 g, 8.55
mmol) in pyridine (15 ml) at ^20ꢀC, acetic anhydride (2.5 ml, 26.7 mmol) in pyridine (10 ml) was
gradually added. The mixture was kept for 24 h at that temperature, then poured into ice-water
and extracted with AcOEt. The combined organic layers were washed with H2SO4 (2N), aq.
NaHCO3 (saturated) and water, dried (MgSO4) and concentrated. Column chromatography
(40:1 CH2Cl2:MeOH) of the crude gave 2,3,6- and 2,4,6-tri-O-acetylderivatives as a mixture. The
treatment of the mixture with Et2O at re¯ux gave 14 (2.260 g, 57%) as a solid. Mp 140±142ꢀC;
[ꢁ]2D8 +8.5 (c 1.3); FABMS: m/z 498 [M+Na]+; IR ꢂmax 1670 cm^1 (CˆO chelated); 1H NMR (500
MHz, CDCl3); ꢀ 9.22 (dd, 1H, JNH,1=9.0, JNH,HCˆ=13.0, NH), 7.95 (d, 1H, HCˆ), 4.96 (t, 1H,
J1,2=J2,3=9.0, H-2), 4.95 (t, 1H, J3,4=J4,5=10.0, H-4), 4.47 (t, 1H, H-1), 4.29±4.19 (m, 5H, H-
6a, 2 CH2CH3), 4.14 (dd, 1H, J5,6b=2.2, J6a,6b=12.4, H-6b), 3.73 (ddd, 1H, J5,6a=4.6, H-5), 3.81
(ddd, 1H, J3,OH=5.0, H-3), 2.13, 2.11, 2.10 (each s, each 3H, 3 Ac), 1.33 and 1.29 (each t, each
3H, JH,H=7.1, 2 CH2CH3) ppm; 13C NMR (125.7 MHz): ꢀ 170.5 (2 C, 2 CO), 170.1, 167.5, 165.6
(3 CO), 157.3 (HCˆ), 94.5 (Cˆ), 86.8 (C-1), 73.6 (C-2), 73.5 (C-5), 72.9 (C-3), 70.2 (C-4), 61.7 (C-6),
60.2, 60.0 (2 CH2CH3), 20.6, (Ac), 20.5 (2 C, 2 Ac), 14.2, and 14.0 (2 CH2CH3) ppm. Anal. calcd
for C20H29O12N: C, 50.52; H, 6.15; N, 2.95. Found: C, 50.50; H, 6.06; N, 3.04.
4.9. 2,4,6-Tri-O-acetyl-N-(2,2-diethoxycarbonylvinyl)-3-O-tri¯yl-ꢃ-d-glucopyranosylamine 15
Tri¯uoromethanesulphonic anhydride (0.21 ml, 0.13 mmol) in pyridine (0.1 ml) was added
dropwise to a solution of 3 in freshly distilled CH2Cl2 (10 ml), and stirred for 2 h at ^15ꢀC. Then
the reaction mixture was poured into cool aq. NaHCO3 (saturated), extracted with CH2Cl2, dried
(MgSO4), and concentrated. FABMS: m/z 630 [M+Na]+. This product was directly used to pre-
pare 16.
4.10. 2,4,6-Tri-O-acetyl-3-azido-3-deoxy-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-allopyranosylamine 16
This was prepared using the same procedure described for 5 and 10. m=0.639 g, 1.053 mmol; x
=7.2 ml; y=0.34, 5.2 mmol; t=1 h; T=rt. Column chromatography (1:1 ether:petroleum ether)
of the residue and crystallisation of the product (0.515 g, 98%) from EtOH gave 16; mp 139±
140ꢀC; [ꢁ]D25 +17.0 (c 0.8); FABMS: m/z 523 [M+Na]+; IR ꢂmax 2130 (N3), and 1659 cm^1 (CˆO
1
chelated); H NMR (500 MHz, CDCl3): ꢀ 9.18 (dd, 1 H, JNH,CHˆ=13.1, JNH,1=9.1, NH), 7.96
(d, 1H, HCˆ), 4.96 (dd, 1H, J1,2=9.1, J2,3=3.2, H-2), 4.93 (dd, 1H, J4,5=10.0, J3,4=3.2, H-4),
4.82 (t, 1H, H-1), 4.46 (t, 1H, H-3), 4.28±4.19 (m, 5H, H-6a, 2 CH2CH3), 4.17±4.13 (m, 1H, H-6b),
4.14±4.10 (m, 1H, H-5), 2.14, 2.12, 2.09 (each s, each 3H, 3 Ac) and 1.37±1.26 (m, 6H, 2 CH2CH3)
ppm; 13C NMR (125.7 MHz): ꢀ 170.5, 169.3, 169.2, 167.9, 165.4 (5 C, 5 CO), 157.6 (CHˆ), 94.3

2480
J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
(Cˆ), 84.1 (C-1), 71.2 (C-5), 69.4 (C-2), 66.9 (C-4), 61.8 (C-6), 60.7 (C-3), 60.2, 60.0 (2 CH2CH3),
20.6, 20.4, 20.3 (3 Ac), 14.2, and 14.1 (CH2CH3) ppm. Anal. calcd for C20H28O11N4: C, 48.00; H,
5.64; N, 11.20. Found: C, 47.84; H, 5.68; N, 10.70.
4.11. 2,4,6-Tri-O-acetyl-3-amino-3-deoxy-N-(2,2-diethoxycarbonylvinyl)-ꢃ-d-glucopyranosylamine
17
A stirred solution of 16 (0.2 g, 0.042 mmol) in (2:3) dioxane:EtOH (10 ml) was hydrogenated in
the presence of Pd(OH)2 for 2.5 h at 4 atm. The catalyst was ®ltered o€ through a Celite pad, and
washed with ethanol. The ®ltrate and washings were combined, and evaporated to give a syrup
which was used without puri®cation in the next step. FABMS: m/z 497 [M+Na]+.
4.12. 2,4,6-Tri-O-acetyl-3-deoxy-N-(2,2-diethoxycarbonylvinyl)-3-isothiocyanato-ꢃ-d-allopyranosyl-
amine 18
This was prepared following the procedure described for 7 and 12. x=0.190 g, 0.4 mmol;
y=6.5 ml; z=0.16 g, 1.6 mmol; k=0.08 ml, 0.8 mmol; t=15 h. TLC (12:1) ether:petroleum ether
(0.090 g, 44% from 16); [ꢁ]2D5 ^19.7 (c 1.0); FABMS: m/z 539 [M+Na]+; IR ꢂmax 2047 (NCS) and
1
1663 cm^1 (CˆO chelated); H NMR (500 MHz, CDCl3): ꢀ 9.24 (dd, 1H, JNH,CHˆ=13.0,
JNH,1=8.9, NH), 7.98 (d, 1H, HCˆ), 4.91±4.86 (m, 3H, H-2, H-3, H-4), 4.82 (t, 1H, J1,2=8.8,
H-1), 4.34±4.19 (m, 6H, H-6a, H-6b, 2 CH2CH3), 4.13 (ddd, 1H, J4,5=9.9, J5,6a=2.1, J5,6b=4.2,
H-5), 2.15, 2.13, 2.10 (each s, each 3H, 3 Ac), 1.33 and 1.31 (each t, each 3H, JH,H=7.1, 2
CH2CH3) ppm; 13C NMR (125.7 MHz): ꢀ 170.3, 169.1, 169.0, 167.9, 165.2 (5 CO), 157.4 (CHˆ),
141.7 (NCS), 94.6 (Cˆ), 84.3 (C-1), 71.6 (C-5), 68.3 (C-2), 66.0 (C-4), 61.6 (C-6), 60.2, 60.0
(2 CH2CH3), 58.1 (C-3), 20.5, 20.4, 20.3 (3 Ac), 14.2 and 14.0 (CH2CH3) ppm. Anal. calcd for
C21H28O11N2S: C, 48.83; H, 5.46; N, 5.42. Found: C, 48.74; H, 5.51; N, 5.75.
4.13. 2-Deoxy-N-(2,2-diethoxycarbonylvinyl)amino-d-mannopyranose 20
To a stirred solution of d-mannosamine hydrochloride (0.25 g, 1.4 mmol) and sodium car-
bonate (0.074 g, 0.7 mmol) in water (1.2 ml), diethyl ethoxymethylenemalonate (0.56 ml, 2.8
mmol) was added and the mixture was stirred for 24 h at rt. The water was evaporated under
reduced pressure. The residue was puri®ed by column chromatography (6:1 CH2Cl2:MeOH) to
yield 13 (0.33 g, 68%) as an amorphous solid. FABMS: m/z 372 [M+Na]+; 13C NMR (125.7
MHz, MeOH-d4): ꢀ 170.0, 166.8 (each 2 C, 4 CO), 162.6 (HCˆb), 161.6 (HCˆa), 94.6 (C-1b),
94.4 (C-1a), 90.4 (Cˆa), 90.2 (Cˆb), 78.8 (C-5b), 74.1 (C-5a), 73.9 (C-3b), 70.6 (C-3a), 69.3 (C-4a),
69.0 (C-4b), 66.1 (C-6b), 65.1 (C-6a), 62.8 (2 C, C-2a, C-2b), 60.9±60.8 (4 C, 4 CH2CH3) and
14.8±14.7 (4 C, 4 CH2CH3) ppm. Anal. calcd for C14H23O9N: C, 48.13; H, 6.64; N, 4.01. Found:
C, 48.19; H, 6.94; N, 3.86.
4.14. 1,3,4,6-Tetra-O-acetyl-2-deoxy-N-(2,2-diethoxycarbonylvinyl)amino-ꢁ-d-mannopyranose 21
and 1,3,4,6-tetra-O-acetyl-2-deoxy-N-(2,2-diethoxycarbonylvinyl)amino-ꢃ-d-mannopyranose 22
Compound 20 (0.25 g, 0.716 mmol) was dissolved in (1:1) acetic anhydride: Py (2.5 ml) at 0ꢀC.
The mixture was stirred at rt for 18.5 h, then poured into ice-water and extracted with ether. The
combined organic layers were washed with H2SO4 (2N), aq. NaHCO3 (saturated) and water,

J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
2481
dried (MgSO4) and concentrated. The residue was puri®ed by column chromatography (1:1
ether:petroleum ether) to give compounds 21 and 22 as amorphous solids.
Compound 21 (0.154 g, 41%); [ꢁ]D26 ^97.1 (c 1.0); FABMS: m/z 540 [M+Na]+; IR ꢂmax 1657
1
cm^1 (CˆO chelated); H NMR (500 MHz, CDCl3): ꢀ 9.56 (dd, 1H, JNH,CHˆ=13.2, JNH,2=9.9,
NH), 7.83 (d, 1H, HCˆ), 6.19 (d, 1H, J1,2=2.0, H-1), 5.34 (dd, 1H, J2,3=3.7, J3,4=9.3, H-3), 5.29
(t, 1H, J4,5=9.3, H-4), 4.25 (q, 2H, JH,H=7.1, CH2CH3), 4.21±4.18 (m, 4H, H-6a, H-6b, CH2CH3),
4.08 (dt, 1H, J5,6a=J5,6b=3.2 Hz, H-5), 3.86 (ddd, 1H, H-2), 2.20, 2.19, 2.08, 2.06 (each s, each
3H, 4 Ac), 1.35 and 1.28 (each t, each 3H, 2 CH2CH3) ppm; 13C NMR (125.7 MHz): ꢀ 170.7, 170.1,
169.0, 168.7, 168.0, 165.4 (6 CO), 158.8 (CHˆ), 92.7 (Cˆ), 91.5 (C-1), 70.6 (C-5), 69.5 (C-3), 65.0 (C-4),
61.1 (C-6), 60.0, 59.8 (2 CH2CH3), 58.9 (C-2), 20.7, 20.5, 20.4, 20.3 (4 Ac), 14.3 and 14.2 (2 CH2CH3)
ppm. Anal. calcd for C22H31O13N: C, 51.06; H, 6.04; N, 2.71. Found: C, 50.97; H, 6.20; N, 2.73.
Compound 22 (0.037 g, 11%); [ꢁ]D26 ^142.8 (c 0.6); FABMS: m/z 540 [M+Na]+; IR ꢂmax 1659
1
cm^1 (CˆO chelated); H NMR (300 MHz, CDCl3): ꢀ 9.62 (dd, 1H, JNH,CHˆ=13.2, JNH,2=9.6,
NH), 7.83 (d, 1H, HCˆ), 5.88 (d, 1H, J1,2=1.3, H-1), 5.23 (t, 1H, J3,4=J4,5=9.8, H-4), 5.09 (dd,
1H, J2,3=3.8, H-3), 4.29±4.15 (m, 6H, H-6a, H-6b, 2 CH2CH3), 3.94 (ddd, 1H, H-2), 3.83 (ddd,
1H, J5,6a=3.6, J5,6b=2.6, H-5), 2.17, 2.12, 2.08, 2.05 (each s, each 3 H, 4 Ac), 1.35 and 1.28 (each
t, each 3H, JH,H=7.1, 2 CH2CH3) ppm; 13C NMR (75.4 MHz): ꢀ 170.7, 169.9, 169.1, 168.7,
168.4, 165.8 (6 CO), 159.4 (CHˆ), 92.3 (Cˆ), 90.3 (C-1), 73.2 (C-5), 71.7 (C-3), 64.8 (C-4), 61.1
(C-6), 59.9, 59.7 (2 CH2CH3), 59.4 (C-2), 20.7, 20.5, 20.4 (4 C, 4 Ac), 14.3 and 14.2 (2 CH2CH3)
ppm. HREIMS calcd for C22H31O13N: 517.1795. Found: 517.1825.
4.15. 1,3,4,6-Tetra-O-acetyl-2-amino-2-deoxy-ꢁ-d-mannopyranose 23
Compound 22 (0.05 g, 0.097 mmol) was dissolved in Cl2/CH2Cl2 (1 ml) at 0ꢀC for 30 min. The
solvent was evaporated under reduced pressure to give a syrup which was used without puri®cation
in the next step. FABMS: m/z 370 [M+Na]+.
4.16. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-isothiocyanato-ꢁ-d-mannopyranose 24
This was prepared following the same procedure described for 7, 12, and 18. x=0.034 g, 0.097
mmol; y=2 ml; z=0.050 g, 0.50 mmol; k=0.03 ml, 0.3 mmol; t=6 h. TLC (3:1) ether:petroleum
ether (0.028 g, 75% from 21); [ꢁ]D26 ^28.8 (c 1.7); FABMS: m/z 412 [M+Na]+; IR ꢂmax 2062 cm^1
(NCS); 1H NMR (500 MHz, CDCl3): ꢀ 6.18 (d, 1H, J1,2=2.0, H-1), 5.39 (t, 1H, J3,4=J4,5=10.0,
H-4), 5.28 (dd, 1H, J2,3=4.0, H-3), 4.26 (dd, 1H, H-2), 4.24 (dd, 1H, J5,6b=4.1, J6a,6b=12.5, H-6a),
4.15 (dd, 1H, J5,6b=2.4, H-6b), 4.05 (ddd, 1H, H-5), 2.17, 2.13, 2.12 and 2.07 (each s, each 3H, 4
Ac) ppm; 13C NMR (125.7 MHz): ꢀ 170.6, 170.0, 169.0, 167.9 (4 CO), 140.2 (NCS), 91.0 (C-1),
70.7 (C-5), 69.2 (C-3), 64.9 (C-4), 61.4 (C-6), 57.5 (C-2), 20.7, 20.6 and 20.5 (4 C, 4 Ac) ppm.
HREIMS calcd for C13H15O7NS: 329.0569. Found: 329.0562.
Acknowledgements
We thank the Direccion General de Ensenanza Superior e Investigaciones Cientõ®cas of Spain
for ®nancial support (grant number PB97/0730), and Bioalava for the samples of 2-amino-2-
deoxy-d-mannose and for the award of a fellowship to D.O.G. This work is part of the European
Programme COST D13, action number D13/0001/99.

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J. Fuentes et al. / Tetrahedron: Asymmetry 11 (2000) 2471±2482
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