Dioxane-type (2-naphthyl)methylene acetals of glycosides and their hydrogenolytic transformation into 6-O- and 4-O-(2-naphthyl)methyl (NAP) ethers

Article abstract of DOI:10.1016/S0040-4020(02)00515-X

α-, β-D-Gluco-, galacto-, 2-deoxy-2-phthalimido-β-D-glucopyranosides with different aglycons (methyl, allyl, p-methoxyphenyl, thioethyl) reacted with 2-naphthaldehyde dimethyl acetal to give rise to 4,6-O-(2-naphthyl)methylene acetals. The acetals were converted into fully protected compounds bearing benzoyl, benzyl, allyl, p-methoxybenzyl groups. The fully alkylated dioxane-type acetals were hydrogenolysed with AlH₃ (3LiAlH₄-AlCl₃) reagent to furnish 4-O-NAP/6-OH derivatives. All acetals were treated with BH₃·Me₃N-AlCl₃ in THF and a reverse regioselectivity was observed, producing 6-O-NAP/4-OH derivatives. Similar regioselectivity was also observed by using NaCNBH₃-HCl reagent. In all reactions very mild reaction conditions were required, regioselectivity was better than 93:7, and the isolated yields were between 83-92%. All compounds were characterised by ¹H and ¹³C NMR spectra. Solid-state and solution conformation of methyl 2,3-di-O-acetyl-4,6-O-(2-naphthyl)methylene-α-D-galactopyranoside were elucidated by X-ray and NMR measurements.

Full text of DOI:10.1016/S0040-4020(02)00515-X

TETRAHEDRON
Pergamon
Tetrahedron 5812002) 5723±5732
Dioxane-type ꢀ2-naphthyl)methylene acetals of glycosides
and their hydrogenolytic transformation into 6-O-
and 4-O-ꢀ2-naphthyl)methyl ꢀNAP) ethers
a
Aniko Borbas, Zoltan B. Szabo, Laszlo Szilagyi, Attila Benyei and Andras Liptak
a
b
c
a,d,p
Â
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aResearch Group for Carbohydrates of the Hungarian Academy of Sciences, P.O. Box 55, Debrecen H-4010, Hungary
bDepartment of Organic Chemistry, Faculty of Science, University of Debrecen, P.O. Box 20, Debrecen H-4010, Hungary
cFaculty of Science, Institute of Physical Chemistry, University of Debrecen, P.O. Box 7, Debrecen H-4010, Hungary
dDepartment of Biochemistry, Faculty of Science, University of Debrecen, P.O. Box 55, Debrecen H-4010, Hungary
Â
Dedicated to Professor Andras Messmer on the occasion of his 80th birthday
Received 25 January 2002; revised 23 April 2002; accepted 16 May 2002
AbstractÐa-, b-d-Gluco-, galacto-, 2-deoxy-2-phthalimido-b-d-glucopyranosides with different aglycons 1methyl, allyl, p-methoxyphenyl,
thioethyl) reacted with 2-naphthaldehyde dimethyl acetal to give rise to 4,6-O-12-naphthyl)methylene acetals. The acetals were converted
into fully protected compounds bearing benzoyl, benzyl, allyl, p-methoxybenzyl groups. The fully alkylated dioxane-type acetals were
hydrogenolysed with AlH3 13LiAlH4±AlCl3) reagent to furnish 4-O-NAP/6-OH derivatives. All acetals were treated with BH3´Me3N±AlCl3
in THF and a reverse regioselectivity was observed, producing 6-O-NAP/4-OH derivatives. Similar regioselectivity was also observed by
using NaCNBH3±HCl reagent. In all reactions very mild reaction conditions were required, regioselectivity was better than 93:7, and the
isolated yields were between 83±92%. All compounds were characterised by 1H and 13C NMR spectra. Solid-state and solution conformation
of methyl 2,3-di-O-acetyl-4,6-O-12-naphthyl)methylene-a-d-galactopyranoside were elucidated by X-ray and NMR measurements. q 2002
Elsevier Science Ltd. All rights reserved.
1. Introduction
based on benzylidene acetals/benzyl ethers is well supple-
mented by a p-methoxy counterpart,13 but the higher acid
sensitivity of these acetals and ethers diminish their prepa-
rative usefulness. Although 12-naphthyl)methyl 1NAP)
ethers have been previously described14±16 their preparative
usefulness was rediscovered17,18 only very recently.
Namely, it was shown that NAP ethers can be hydrogeno-
lysed in the presence of benzyl ethers or esters15 and they are
less sensitive to acids than p-methoxybenzyl ethers. The
most important observation, however, is that the NAP ethers
can easily be removed by DDQ 12,3-dichloro-5,6-dicyano-
1,4-benzoquinone) under conditions when other usual
protecting groups like acetyl, pivaloyl, phthalimido, benzyl
and benzylidene survive.17,18 On the basis of these observa-
tions the syntheses of some very complex oligosaccharides
have also been accomplished.19±22 In 2000 we have reported
on the synthesis of 12-naphthyl)methylene acetals of hexa-
pyranosides and converted them into 12-naphthyl)methyl
1NAP) ethers.23 To our knowledge, only the synthesis
of n-pentenyl 2,3-di-O-benzoyl-4,6-O-12-naphthyl)methyl-
ene-b-d-galactopyranosyl-11!4)-2,3,6-tri-O-benzoyl-b-d-
glucopyranoside24 has been reported before. Last year
hydrogenolysis of dioxane-type 12-naphtyl)methylene
acetals of sugars were also published by Spencer et al.25
For the hydrogenolysis of compound 723 Spencer et al.25
used DIBAL-H in toluene±dichloromethane and the
The protecting group strategy plays an essential role not
only in the design and syntheses of complex oligo-
saccharides1 but also in the chemical transformation of
sugars.2 Acetals2±4 and easily removable ether groups5
belong to the most frequently applied protecting groups.
The rules for the regio-,6,7 stereo-8 and chemoselective9
transformations of the benzylidene acetals into hydroxy/
benzyl ether derivatives are well-known. Although many
reagents were used for hydrogenolysis of acetals, three
of them are used in general: 1i) LiAlH4±AlCl3;6,7
1ii) NaCNBH3±HCl10,11 1or other strong protic acids); and
1iii) BH3´Me3N±AlCl3.12 Reagent 1i) results in 4-O-alkyl/
aryl/6-OH products, reagent 1ii) induces opposite regio-
selectivity producing 4-OH/6-O-alkyl/aryl derivatives. The
regioselectivity of the acetal cleavage using reagent 1iii) is
strongly solvent dependent, either of 4-OH/6-O-ether and
6-OH/4-O-ether can be prepared, with moderate yields,
however, in some cases. The blocking group strategy
Keywords: glycosides; acetals; sugars.
Corresponding author. Address: Research Group for Carbohydrates of
the Hungarian Academy of Sciences, P.O. Box 55, Debrecen H-4010,
Hungary. Tel.: 136-52-512900x2256; fax: 136-52-512913; e-mail:
liptaka@tigris.klte.hu
p
0040±4020/02/$ - see front matter q 2002 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020102)00515-X

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5724
Figure 1. Reaction conditions: 1a) 2-1dimethoxymethyl)naphthalene 11.2 equiv.), pTSA, DMF, rt, overnight 187±92%); 1b) benzoyl chloride, pyridine
181.5%); 1c) benzyl bromide, NaH, DMF 191±94%); 1d) allyl bromide, NaH, DMF 188.3%); 1e) p-methoxybenzyl chloride, NaH, DMF 183.5%); 1f) acetic
anhydride, pyridine 183%).
4-ONAP/6-OH derivative 12623)was obtained in a yield
of 60%. In the case of methyl 2,3-di-O-benzyl-4,6-O-
12-naphthyl)methylene-a-d-galactopyranoside 1compound
22) the authors assigned R-con®guration to the acetal carbon
in which the bulky naphthyl group must have an axial
arrangement, but they did not gave any structural para-
meters to support this con®guration. The hydrogenolysis
of this poorly characterised compound with Et3SiH±
In this paper we wish to report on the extension of our
previous work and to con®rm the structure of all synthesized
compounds giving full experimental details and spectro-
scopic parameters.
2. Results and discussions
Ê
TfOH-4 A Ms in dichloromethane resulted in 4-ONAP/
2.1. Preparation of 4,6-O-ꢀ2-naphthyl)methylene acetals
of hexopyranosides
6-OH derivative 184%), however, its hydrogenolysis with
Et3SiH±PhBCl2 gave the 6-ONAP/4-OH compound 177%).
These structures had not been veri®ed by any data.
In the glucopyranoside series methyl a-11), methyl

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5725
hindrance was observed. Starting from methyl a-116)
methyl b-117) and p-methoxyphenyl b-d-galactopyranoside
118) crystalline acetals 119±21) were isolated with good to
excellent yields. Compounds 19±21 were benzylated to get
the fully protected compounds 22±24. For comparative
X-ray crystallographic studies compound 19 was acetylated
and the di-O-acetyl derivative 125) gave a single crystal
suitable for X-ray structure determination. ORTEP view
of 25 at 50% probability level with numbering scheme is
shown at Fig. 2. These experiments unambiguously veri®ed
that the naphthyl group had an equatorial arrangement.
1
13C and H NMR spectra of all synthesised acetals were
recorded and assigned 1Tables 1±4). The characteristic
spectral parameters were very similar to those observed
for benzylidene and substituted benzylidene acetals,26
namely, low ®eld 13C shift for C-6 and C-4 and extremely
high ®eld chemical shifts for C-5, especially in the case of
the a-anomers. In the case of the b-anomers, the high ®eld
shifts of C-5 are less pronounced. These characteristic
carbon chemical shift values are very similar in the gluco-
and galacto series. The chemical shift values of the acetalic
carbon show only small variations between 101 and
102 ppm. The typical aromatic 1naphthyl) resonances are
shown in Section 3.
Figure 2. ORTEP view of 25 shown at 50% probability level. Only one of
the molecules in the asymmetric unit is shown.
2,3-di-O-benzyl-a-12), allyl b-13), p-methoxyphenyl b-d-
glucopyranoside 14) were reacted with 2-naphthaldehyde
dimethyl acetal in DMF solution in the presence of p-tolu-
enesulfonic acid 1p-TSA) to give crystalline dioxane-type
acetals 16±9). Compound 1 or 2 reacted with 2-naphthalde-
hyde too, but the acetal-formation was slow and the reaction
did not go to completion overnight. Similar treatment of
ethyl 2-deoxy-2-phthalimido-1-thio-b-d-glucopyranoside
15) with 2-naphthaldehyde dimethyl acetal yielded the
desired acetal compound 110). Benzylation of compounds
6, 8 and 9 gave the fully protected dioxane-type acetals 7, 11
and 12. Benzoylation of 6 resulted in compound 13.
Compound 10 was allylated or p-methoxybenzylated to
obtain compounds 14 and 15 1Fig. 1).
2.2. Hydrogenolysis of 4,6-O-ꢀ2-naphthyl)methylene
acetals of pyranosides
As mentioned before, in the ®eld of carbohydrates
three reagents 1LiAlH4±AlCl3;6,7 NaCNBH3±HCl10,11 and
BH3´Me3N±AlCl312) are generally applied for the trans-
formation of benzylidene and p-methoxybenzylidene
acetals into hydroxy/benzyl or hydroxy/p-methoxybenzyl
ethers. Recently, additional reagents were proposed for
preparative purposes, namely triethylsilane±tri¯uoroacetic
acid,27 BH3´Me2NH±BF3´OEt2 in CH3CN,28 triethylsilane±
29
TiCl4 and BH3´THF±Bu2BOTf.30
All these reagents, except the LiAlH4±AlCl3, can be used in
the presence of ethers, esters, amides and imides. The
LiAlH4±AlCl3 is compatible only with ether substituents,
providing excellent regioselectivity, the 4-OBn/6-OBn
The preparation of the 12-naphthyl)methylene acetals in the
galactopyranoside series proceeded also very smoothly and,
although the two six-membered rings are cis-fused, no steric
Table 1. 13C NMR data 1d) for compounds 6±25
Compounds
C-1
C-2
C-3
C-4
C-5
C-6
C-ac
C-aglycon
55.3 1OCH3)
55.3 1OCH3)
70.6, 118.3, 133.7 1OAll)
55.0 1OCH3)
14.8, 24.1 1SEt)
70.7, 117.5, 133.7 1OAll)
55.6 1OCH3)
6
7
8
9
99.9
99.2
72.6a
79.1a
74.5a
73.9a
55.4
81.5a
81.3a
72.5a
54.5
54.6
68.8a
72.1a
69.7
75.2
79.1a
78.0
68.2
71.1a
78.5a
81.1
82.1
80.6
80.4
81.9a
82.1a
81.9a
62.3
62.3
66.4
65.8
69.4
66.0
66.1
62.6
70.3
70.4
62.5
65.9
66.0
68.9
69.1
68.7
68.0
68.6
68.8
68.8
69.0
68.4
68.5
69.1
68.7
68.6
101.8
101.3
101.9
101.0
101.9
101.3
101.3
102.1
102.2
82.2a
103.2
103.2
97.7
73.1a
72.7a
70.3
10
11
12
13
14
15
19
20
21
22
23
24
25
80.9a
80.8a
69.5a
79.5
101.855.4 1OCH
)
3
82.5a
81.5
100.3
103.9
101.9
99.4
104.7
103.2
97.7
1.7 75.88
82.9
101.1
101.4
101.1
100.1
100.1
14.7, 23.8 1SEt)
14.8, 24.0 1SEt)
55.3 1OCH3)
56.2 1OCH3)
54.9 1OCH3)
a
74.8
76.2
75.7
75.5
68.6a
70.0a
71.9
75.874.862.4
69.4
101.1
55.4 1OCH
)
3
78.3a
79.2
68.5
73.9
73.8
74.0
66.3
69.2
62.0
69.2
66.5
69.1
101.4
101.4
101.0
57.0 1OCH3)
55.8 1OCH3)
55.5 1OCH3)
a
Interchangeable assignments.

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5726
Table 2. 13C NMR data 1d) for compounds 26±40
Compounds
C-1
C-2
C-3
C-4
C-5
C-6
C-aglycon
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
98.1
102.8
102.5
98.1
102.7
102.7
81.1
80.9
96.9
81.9a
84.5
84.4
79.5
81.6
81.5
54.5
54.3
71.4
79.9a
82.3
82.0
81.4
83.9
84.0
78.0
77.8
73.7
79.0
79.4a
79.3a
75.6
80.4
78.6
77.6
77.6
77.3
69.9
71.3
71.1
79.8
79.1
73.9
75.1
74.0
75.4
67.9
66.7
66.7
70.6
75.0
75.1
70.6
74.0
74.4
73.2
74.0
76.2
70.3
72.9
72.5
77.4
78.9
80.5
61.855.1 1OCH
62.1
62.0
69.2
70.1
69.9
70.5
70.5
69.2
62.3
61.6
61.9
69.5
69.1
69.2
)
3
70.6, 118.3, 133.7 1OAll)
55.6 1OCH3)
55.1 1OCH3)
70.3, 117.3, 133.9 1OAll)
55.5 1OCH3)
14.8, 23.9 1SEt)
55.4 1OCH3)
55.2 1OCH3)
55.2 1OCH3)
56.81OCH 3)
98.7
76.3
a
1.9 100.88
2.1 102.88
98.4
a
55.6 1OCH3)
55.1 1OCH3)
56.8 1OCH3)
55.5 1OCH3)
69.5
73.0
73.5
104.6
102.8
a
Interchangeable assignments.
Table 3. 1H NMR chemical shifts 1d in ppm) and coupling constants 1J in Hz) for compounds 6±25
Compounds
H-1, J1,2
H-2, J2,3
H-3, J3,4
H-4, J4,5
H-5, J5,6a
H-6a, Jgem
H-6b, J5,6b
H-ac
H-aglycon
6a
4.74d, 3.8
4.69d, 3.7
4.44d, 7.9
4.86d, 7.8
3.59dd, 9.3
3.68dd, 9.3
3.54dd, 9.2
3.52c
3.92t, 9.3
4.19t, 9.3
3.83t, 9.2
3.75t, 9.83.53
3.48t, 9.3 3.81dt, 4.7 4.30dd, 10.2 3.74dd, 10.2 5.64s 3.0 1OCH3)
7a
3.75t, 9.3 3.97dt, 4.8 4.41dd, 10.2 3.84t, 10.2
3.59t, 9.2 3.46dt, 10.5 4.36dd, 10.5 3.82t, 10.5
3.48dt, 4.7 4.27dd, 10.1 3.65dd, 4.5
4.30t, 9.84.70dt, 3.3 4.43dd, 10.0 3.6±3.9m
3.85t, 10.0 3.45m, 10.0 3.75dd, 10.0 3.40dd, 4.8
5.76s 3.08 1OCH3)
8a
5.67s 5.93;5.23;5.33;4.13 1allyl)
5.66s 3.27 1OCH3) 6.81;7.02 1arom)
5.72s 1.20 t; 2.70 m 1SEt)
9b
c
10a
11a
12a
13a
14a
15a
19d
20b
21b
22a
23a
24a
25a
5.44d, 10.0 3.60±3.90m
4.58d, 7.8
4.99d, 7.9
5.20d, 3.85.27dd, 9.86.10t, 9.8 3.92t, 9.84.13dt, 4.84.42dd, 10.3 3.96t, 9.6
5.45d, 10.6 4.39t, 10.4
5.40d, 10.6 4.31t, 10.5
3.52t, 8.0
3.71t, 8.3
3.76t, 10.0
3.79±3.83m
5.72s 5.95;5.38;5.27;4.42;4.17 1allyl)
5.70s 3.74 1OCH3) 6.80;6.95 1arom)
3.50m
4.39dd, 10.5 3.86t, 10.0
5.72s 3.44 1OCH
)
3
4.50t, 10.2
4.50c
3.80t, 9.0 3.76m, 4.7 4.45, 10.0
3.85, 10.0
3.90c
4.30dd, 12.2 4.12, 2.0
5.72s 1.20t;2.70m 1SEt)
5.81s 1.21t;2.70m 1SEt)
5.72s 3.45 1OCH3)
c
3.90c
3.79dt, 4.84.50
4.90d, 3.3
4.15c
3.85±4.10
3.56c
3.81, 9.7
4.10dd, 10.0 4.00dd, 3.4
3.87dd, 9.5
4.13dd, 9.8
3.56c
3.66, 3.5
4.14c
4.21, ,0
3.45
3.57, ,1
4.18, 12.2
4.18, 11.9
4.23
4.07, 1.9
4.10, 1.2
4.03
5.63s 3.47 1OCH3)
4.78d, 7.7
4.79d, 3.5
4.29d, 7.6
4.88d, 7.8
5.16d, 3.2
5.67s 3.68 1OCH3) 6.73;7.00 1arom)
5.62s 3.381OCH 3)
5.63s 3.61 1OCH3)
5.65s 3.76 1OCH3), 6.73; 7.00 1arom)
5.69s 3.45 1OCH3)
4.21d, ,0 3.60m
4.13d, ,0 3.29br
4.20d, 3.6 3.40dd, 1.0 4.36dd, 12.2 4.08dd, 1.6
3.56dd, 3.4
3.65dd, 3.6
4.32dd, 12.3 4.03dd, 1.5
5.42dd, 10.85.39dd, 10.9 4.56d, ,0 3.82br, ,1 4.35d, 12.5
4.14dd, 1.5
a
Measured in CDCl3.
b
c
d
Measured in DMSO-d6±CDCl3.
Overlap.
Measured in MeOD±CDCl3.
Table 4. 1H NMR chemical shifts 1d in ppm) and coupling constants 1J in Hz) for compounds 26±40
H-1, J1,2
H-2, J2,3
H-3, J3,4
H-4, J4,5
H-5, J5,6a
H-6a, Jgem
H-6b, J5,6b
H-aglycon
3.38s 1OCH3)
5.91;5.31;5.18;4.36;4.12 1allyl)
3.82 1OCH3) 6.88;7.05 1arom)
3.30 1OCH3)
5.90; 5.31; 5.20; 4.36; 4.17
1allyl)
3.77 1OCH3) 6.88;7.05 1arom)
2.65;1.20 1SEt)
2.63;1.17 1SEt)
26
27
28
29
30
4.57d, 3.6
4.47d, 7.83.424t, 8
4.92d, 7.5
4.63d, 3.1
4.53b
3.51dd, 9.7
4.04dd, 8.8
3.59t, 9.0a
3.67±3.88
3.79t, 9.2
3.56±3.83m
3.67t, 9.0
3.67±3.88
3.61t, 9.2
3.56±3.83m
3.36m, 2.5
3.55m
3.68±3.75m
,3.65m, 3.5
3.56±3.83m
3.86dd, 12.0
3.96dd, 11.8
3.56±3.83
3.70dd, 4.6
,3.75
a
3.67±3.88
3.53dd, 9.5
3.42±3.60
3.87dd, 10.5
3.92dd, 10.5
3.81dd, 5.0
31
32
33
34
35
36
37
38
39
40
4.81d, ,10
5.32d, 9.83.65±4.33
5.30d, 9.83.65±4.33
5.15d, 3.6
4.72d, 4.2
4.25d, 7.83.45±3.90
3.50±3.85
,3.75
5.27dd, 10.1
4.07dd, 10.1
5.79t, 8.6
3.94dd, 3.0
3.97bm
3.89d, ,0
4.00bm, 4.0
3.88dd, 10.5
3.73dd, 10.3
3.45±3.90
3.8dd, 3.1
3.47dd, 4.0
3.41 1OCH3)
3.33 1OCH3)
,3.7bm, 6.7
3.30brt
3.52 1OCH
)
3
4.89d, 7.7
4.67d, 3.6
4.27d, 7.7
4.86d, 7.8
4.14dd, 9.7
3.62dd, 2.9
3.86dd, 3.0
3.46dd, 3.4
3.58dd, 3.3
3.86d, ,0
4.02d, ,0
4.00br, ,0
4.07d, ,0
3.83m, 6.7
3.83dd, 5.4
3.65m,35d.8d3, .180
3.70t, 4.7
4.87dd, 12.0
3.75dd, 10.2
3.77dd, 6.0
3.88dd, 10.1
3.47m
3.75 1OCH3) 6.80;7.00 1arom)
3.38 1OCH3)
3.89dd, 8.0
3.57t, 9.4
3.92t, 9.1
3.70dd, 6.4
3.56 1OCH
3.82dd, 6.3
)
3
3.70 1OCH3) 6.77;7.04 1arom)
Measured in CDCl3.
Interchangeable assignments.
Overlap.
a
b

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5727
Table 5. The product distribution for the reductive ring-opening reactions
Starting compounds
3LiAlH4±AlCl3 1%)
BH3´Me3N±AlCl3 1%)
4-ONAP/6-OH 6-ONAP/4-OH
4-ONAP/6-OH
6-ONAP/4-OH
7
97
3
10.3
0
3.5
3.9
5.6
6.9
6.9
10.5
4.895.2
6.9
5.2
93.1
93.1
89.5
11
12
22
23
24
89.7
100
96.5
96.1
94.4
93.1
94.8
ratios being $9:1. The Et3SiH/TiCl4 and the BH3´THF/
Bu2BOTf reagents gave rise to the formation of 4-OBn
ethers, the latter one, however, provided mixtures, occasion-
ally. All other reagents resulted in 6-O-benzyl ethers, but
Et3SiH±CF3COOH27 did not work in the galactopyranoside
series.
27 1,90%). These results demonstrated that the method is
equally useful both in the gluco- and in the galacto series.
Fully substituted 4,6-O-12-naphthyl)methylene acetals 17,
11±15 and 22±24) in both series were treated with
6 equiv. of BH3´Me3N±AlCl3 reagent in abs. THF at room
temperature to give rise to the 6-ONAP ethers 129±34 and
38±40), the regioselectivities being better than 93:7, except
for 12 1,90%). Hydrogenolysis experiments on 11 and 12
indicated, that the aglycon has greater in¯uence on the
regioselectivity in the glucoside series, than in the galacto-
side series, using either LiAlH4±AlCl3 or BH3´Me3N±AlCl3
reagents. The regioselectivity of the ring cleavage reactions
with Me3N´BH3±AlCl3 was somewhat higher for the
galactopyranoside derivatives, than for the glucopyrano-
sides.
The ether substituted 4,6-O-12-naphthyl)methylene acetals
17, 11, 12, 22±24) were cleaved by LiAlH4±AlCl3 reagent
under very mild conditions, with only 3 equivalents of AlH3
13LiAlH41AlCl3), at room temperature in dichloromethane/
diethyl ether 11:1) solution. The reaction time varied
between 20 min and 3 h. The regioselectivity was better
than 94:6 1Table 5, determined by HPLC), favouring the
4-O-NAP ether 126, 28, 35±37, Fig. 3). The allyl glucoside
11 could be cleaved with slightly lower regioselectivity to
Figure 3. Hydrogenolytic products of the 12-naphthyl)methylene acetals of hexopyranosides.

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5728
Figure 4. Reaction conditions: 1a) DDQ 10.4 equiv.) in CH3CN/H2O 19:1), 2±3 h 179±83%); 1b) DDQ 11.2 equiv.) in CH2Cl2/MeOH 14:1), 1 drop of water,
30±60 min 180±82%).
It is worth mentioning that the cleavage of 15 using
BH3´Me3N±AlCl3 reagent gave ethyl 2-deoxy-6-O-12-
naphthyl)methyl-3-O-1p-methoxy)benzyl-2-phthalimido-1-
thio-b-d-glucopyranoside 133) in a yield of 87%, without
appreciable loss of the sensitive p-methoxybenzyl group.
and benzylidene).17,18 We have found that DDQ smoothly
removed the NAP group, while other protecting groups
1benzoyl, TBDMS) survived.23 Treatment of 28 or 31 with
1.2 equiv. of DDQ in CH2Cl2/MeOH 14:1) yielded 41,
respectively, in 30 min. Similarly, compound 32 resulted
in the diol 42 1Fig. 4).
Treatment of 7 and 13 with NaCNBH3±HCl 112 equiv.) in
THF, resulted in the formation of the 6-ONAP ethers 29 and
34 in a ratio of 91:9. The product distribution of the ring
opening reaction was determined by HPLC and the data are
presented in Table 5.
3. Experimental
3.1. General methods
The structures of the ONAP ethers are evident from 13C
Optical rotations were measured at room temperature with a
Perkin±Elmer 241 automatic polarimeter. Melting points
were determined on a Ko¯er hot-stage apparatus and are
uncorrected. TLC was performed on Kieselgel 60 F254
1Merck) with detection by charring with 50% aqueous
sulfuric acid. Column chromatography was performed on
Silica Gel 60 1E. Merck 0.062±0.200 nm). The organic
solutions were dried over MgSO4, and concentrated in
1
NMR data. Complete H and 13C NMR assignments were
accomplished for all new compounds 1Table 1±4). The 13C
a-shifts for the ONAP ethers are generally ,17 ppm. It is
noteworthy, that compound 32 and 33 showed unusual high
®eld chemical shifts for C-4. We could not found com-
pletely assigned 13C NMR data for related compounds in
the literature. On the basis of the skeleton chemical shift
values of ethyl 3,6-di-O-benzyl-2-deoxy-2-phthalimido-1-
thio-b-d-glucopyranoside31 and 3-O-allyl-6-O-benzyl-2-
deoxy-2-phthalimido-b-d-glucopyranosyl azide32 ,79.5±
77.4 ppm chemical shifts can be assigned as C-4, similarly
to our observetion for 32 and 33.
1
vacuum. The H 1200, 360 and 500 MHz) and 13C NMR
150.3, 90.54, 125.76 MHz) spectra were recorded with
Bruker WP-200SY, Bruker AM-360 and Bruker DRX-500
spectrometers for solutions in CDCl3 or in D2O. Internal
1
references: TMS 10.00 ppm for H), CDCl3 177.00 ppm for
13C). Single crystal of 25, suitable for X-ray diffraction
measurement was obtained after recrystallization from
EtOAc±nhexane. X-Ray diffraction data were collected at
293 11) K, Enraf Nonius MACH3 diffractometer, Mo Ka
We also investigated the stability and the compatibility of
the new acetals and the NAP ethers with other generally
used protecting groups. Alkylation, acylation or silylation
can be achieved in high yield in the presence of the
12-naphthyl)methylene acetals.23
Ê
radiation lˆ0.71073 A. Colourless block crystals 10.68£
0.44£0.28mm 3) of C22H24O8, Mˆ416.41, monoclinic,
Ê
Ê
Ê
aˆ15.580 18) A, bˆ8.894 16) A, cˆ16.232 16) A,
Ê 3
2.3. Removal of the 2-ꢀnaphthyl)methylene acetals and
NAP ethers
bˆ101.7 11)8, Vˆ2203 12) A , Zˆ4, space group: P21,
rcalcˆ1.256 g cm23. v ±2u motion, umaxˆ268, 4586
measured, 3179 re¯ections were unique with I.2s1I),
decay: 5%. The structure was solved using the SIR-92 soft-
ware34 and re®ned on F2 using SHELX-9735 program, publi-
cation material was prepared with the WINGX-97 suite,36
R1F)ˆ 0.0676 and wR1F2)ˆ0.2137 for 4586 re¯ections, 541
The removal of isopropylidene, benzylidene as well as
dithioacetal protecting groups of sugars by DDQ has been
reported.33 The new acetal blocking group reported here can
also be removed by using DDQ at room temperature, in a
relatively short time 12±3 h); the yields are nearly quanti-
tative 112!41 and 14!42). These reactions required
0.4 equiv. of freshly crystallized DDQ in acetonitrile/water
19:1) solution 1Fig. 4).
parameters.37 Residual electron density: 0.502/20.312 e A .
Ê 23
A Hewlett±Packard 1090 series II Liquid Chromatograph
equipped with a diode array detector 1DAD), an automatic
samples and Chem Station were used for the separation
experiments. The separation was performed using a
LiChrospher Si-60 1250£4 mm2) 5 mm column. Hexane/
The NAP ethers can also be cleaved in the presence of a
variety of blocking groups 1acetyl, pivaloyl, NPhth, benzyl

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5729
ethyl acetate mixture was used as eluent. The ef¯uent was
monitored for UV active groups at 270 nm. The component
ratio was given on the basis of the Area% of HPLC analysis.
3.6. General method E for the removal of 4,6-O-ꢀ2-
naphthyl)methylene acetals of hexopyranosides
To a solution of starting acetal compound in acetonitrile/
water 9:1 110 ml/100 mg) was added freshly crystallized
DDQ 10.4 equiv.). The reaction mixture was stirred at
room temperature for several hours. After complete con-
version the mixture was evaporated in vacuo, and the
residue was puri®ed by column chromatography.
3.2. General method A for the preparation of 4,6-O-ꢀ2-
naphthyl)methylene acetals of hexopyranosides ꢀ6±10,
19±21)
To a solution of starting hexopyranoside in dry DMF
10.01 mol in 3±5 ml) 2-naphthaldehyde dimethyl acetal
11.2 equiv.) and catalytic amount of p-toluenesulfonic acid
were added. The reaction mixture was stirred at room
temperature for 24 h, then neutralized with triethylamine
and evaporated in vacuo. The residue was dissolved in
dichloromethane, washed with water 13£50 ml), dried
and evaporated. The crude product was puri®ed by
crystallization.
3.7. General method F for the removal of ꢀ2-naphthyl)-
methyl ether group of hexopyranosides
To a solution of starting NAP-ether in dichloromethane/
methanol 4:1 11±2 ml/100 mg) freshly crystallized DDQ
11.2 equiv.) and one drop of water were added, and the
mixture was stirred at room temperature. After complete
conversion 130±60 min) the mixture was evaporated in
vacuo, and the residue was puri®ed by column chroma-
tography.
In large scale 10.03 mol and above), the reaction mixture
was poured into water, the precipitated product was ®ltered
off and washed with water until neutral. The excess of the
reagent was removed by successive washing with hexane,
then the crude product was crystallized.
3.7.1. Methyl 4,6-O-ꢀ2-naphthyl)methylene-a-d-gluco-
pyranoside ꢀ6). Compound 1 was converted by method A
to give 6 191.5%) as a white solid, mp 193±1948C 1from
EtOH), [a]Dˆ199.30 1c 0.50, chloroform); nmax 1KBr)
3464, 2956, 1344, 1128, 1072, 1056, 808, 756, 484 cm21
;
3.3. General method B for the alkylation of 4,6-O-ꢀ2-
naphthyl)methylene acetals of hexopyranosides ꢀ7, 11,
12, 14, 15, 22±24)
1H NMR d 1500 MHz, CDCl3) 7.95±7.40 17H, aromatic);
13C NMR d 1125 MHz, CDCl3) 134.4, 133.7, 132.81Cq,
aromatic), 128.3, 128.1, 127.6, 126.4, 126.1, 125.8, 123.7
1CH, aromatic). Anal. calcd for C18H20O6: C 65.05, H 6.07.
Found: C 65.01, H 6.10.
To a solution of the starting acetal compound in dry DMF
10.01 mol in 10 ml) 80% NaH was added at 08C 11.5 equiv./
OH) and stirred for 30 min. Then alkyl bromide/chloride
11.2 equiv./OH) was added to the mixture and stirred until
the t.l.c. showed complete conversion 11±2 h). After usual
work-up procedure the residue was puri®ed by crystalli-
zation or column chromatography.
3.7.2. Methyl 2,3-di-O-benzyl-4,6-O-ꢀ2-naphthyl)methyl-
ene-a-d-glucopyranoside ꢀ7). Compound 238 was con-
verted by method A to give 7 194%) as white needles,
mp 118±1198C 1from EtOH), [a]Dˆ254.80 1c 0.33,
chloroform).
3.4. General method C for the hydrogenolysis of 4,6-O-
ꢀ2-naphthyl)methylene acetals of hexopyranosides with
LiAlH4±AlCl3 ꢀ26±28, 35±37)
Compound 7 was also prepared from 6 by method B using
benzyl bromide, as the reagent. nmax 1KBr) 2970, 2914,
1454, 1386, 1088, 1052, 854, 792, 762, 474 cm21 1H
;
NMR d 1200 MHz, CDCl3) 8.05±7.20 117H, m, aromatic);
To a stirred solution of the starting acetal compound
10.01 mol) and LiAlH4 14.5 equiv.) in dry CH2Cl2/Et2O
12:1, 15 ml), AlCl3 in Et2O 11.5 equiv. in 10 ml) was
added dropwise at room temperature. After complete
conversion 120 min±2 h) 2±3 ml of ethyl-acetate and 3±5
drops of water were added, the mixture was diluted with
ethyl acetate, washed with water 13£50 ml), dried and
concentrated. The residue was puri®ed by crystallization
or column chromatography.
13C NMR d 150 MHz, CDCl3) 138.7, 138.1, 134.7 12£),
133.5, 132.81C , aromatic), 128.4-123.6 1CH, aromatic).
q
Anal. calcd for C32H32O6: C 74.97, H 6.30. Found: C
75.02, H 6.22.
3.7.3. Allyl 4,6-O-ꢀ2-naphthyl)methylene-b-d-gluco-
pyranoside ꢀ8). Compound 339 was converted by method
A to give 8 187.2%) as white needles, mp 162±1638C 1from
EtOH), [a]Dˆ245.40 1c 0.61, chloroform). Anal. calcd for
C20H22O6: C 67.01, H 6.19. Found: C 67.11, H 6.13.
3.5. General method D for the hydrogenolysis of 4,6-O-
ꢀ2-naphthyl)methylene acetals of hexopyranosides with
Me3N´BH3±AlCl3 ꢀ29±33, 38±40)
3.7.4. p-Methoxyphenyl 4,6-O-ꢀ2-naphthyl)methylene-b-
d-glucopyranoside ꢀ9). Compound 440 was converted by
method A to give 9 192%)as white crystals, mp 207±
2108C 1from EtOH), [a]Dˆ234.13 1c 0.15, chloroform);
nmax 1KBr) 3404, 2888, 1508, 1402, 1366, 1220, 1176,
1082, 824, 760, 480 cm21; Anal. calcd for C24H24O7: C
67.91, H 5.70. Found: C 67.71, H 5.66.
Ê
The mixture of the starting acetal compound 10.01 mol), 4 A
molecular sieves 12 g) and Me3N´BH3 16 equiv.) in dry THF
130 ml) was stirred for 30 min at room temperature, then
AlCl3 16 equiv.) was added. After complete conversion
12±3 h) the mixture was ®ltered through a layer of Celite,
diluted with CH2Cl2, washed with water, dried, concentrated
and co-evaporated three times with MeOH.
3.7.5. Ethyl 2-deoxy-4,6-O-ꢀ2-naphthyl)methylene-2-
phthalimido-1-thio-b-d-glucopyranoside ꢀ10). Compound

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A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5730
541 was converted by method A to give 10 191%) as white
needles, mp 105±1088C 1from EtOH), [a]Dˆ211.781 c
0.24, chloroform); nmax 1KBr) 3442, 2970, 2872, 1774,
1714, 1626, 1388, 1092, 748, 480 cm21; Anal. calcd for
C27H25O6NS: C 65.97, H 5.13, N 2.85, S 6.52. Found: C
66.11, H 5.16, N 2.91, S 6.47.
3422, 2362, 1344, 1092, 1044, 794, 778, 478 cm21; Anal.
calcd for C18H20O6: C 65.05, H 6.07. Found: C 64.84, H
6.01.
3.7.12. Methyl 4,6-O-ꢀ2-naphthyl)methylene-b-d-galac-
topyranoside ꢀ20). Compound 17 was converted by method
A to give 20 192.6%) as white solid, mp 223±2248C 1from
EtOH), [a]Dˆ236.75 1c 0.22, chloroform); nmax 1KBr)
3424, 2858, 1630, 1366, 1174, 1078, 1050, 1002, 822,
780, 480 cm21. Anal. calcd for C18H20O6: C 65.05, H
6.07. Found: C 64.97, H 6.11.
3.7.6. Allyl 2,3-di-O-benzyl-4,6-O-ꢀ2-naphthyl)methyl-
ene-b-d-glucopyranoside ꢀ11). Compound 8 was con-
verted by method B using benzyl bromide as the reagent
to give the colourless syrupy 11 191.4% after column
chromatography in hexane/EtOAc, 8:2), [a]Dˆ252.41
1c 0.41, chloroform). Anal. calcd for C34H44O6: C 74.42,
H 8.08. Found: C 74.70, H 8.06.
3.7.13. p-Methoxyphenyl 4,6-O-ꢀ2-naphthyl)methylene-
b-d-galactopyranoside ꢀ21). Compound 1842 was
converted by method A to give 21 191%) as white solid,
mp 254±2578C 1from EtOH), [a]Dˆ285.38 1c 0.22,
DMSO); nmax 1KBr) 3428, 2862, 1508, 1402, 1366, 1220,
1176, 1082, 824, 760, 480 cm21. Anal. calcd for C24H24O7:
C 67.91, H 5.70. Found: C 68.24, H 5.80.
3.7.7.
p-Methoxyphenyl
2,3-di-O-benzyl-4,6-O-ꢀ2-
naphthyl)methylene-b-d-glucopyranoside ꢀ12). Com-
pound 9 was converted by method B using benzyl bromide
as the reagent to give 12 194%) as white needles, mp 180±
1838C 1from EtOH), [a]Dˆ231.1 1c 0.66, chloroform);
nmax 1KBr) 3432, 2876, 1508, 1244, 1092, 1030, 798, 746,
472 cm21; Anal. calcd for C38H36O7: C 75.48, H 6.00.
Found: C 75.81, H 6.02.
3.7.14. Methyl 2,3-di-O-benzyl-4,6-O-ꢀ2-naphthyl)-
methylene-a-d-galactopyranoside ꢀ22). Compound 19
was converted by method B to give 22 193.7%) as white
needles, mp 122±1248C 1from EtOH), [a]Dˆ189.23 1c
0.21, chloroform); nmax 1KBr) 3458, 2908, 1452, 1366,
1098, 1056, 1026, 820, 780, 474 cm21; Anal. calcd for
C32H32O6: C 74.98, H 6.29. Found: C 75.34, H 6.21.
3.7.8. Methyl 2,3-di-O-benzoyl-4,6-O-ꢀ2-naphthyl)-
methylene-a-d-glucopyranoside ꢀ13). To a stirred solution
of compound 6 11.66 g, 5 mmol) in dry pyridine 15 ml)
benzoyl chloride 11.74 ml, 15 mmol) was added at 08C.
After usual work-up procedure the residue was crystallized
from EtOH to give 13 181.5%) as white needles, mp 216±
3.7.15. Methyl 2,3-di-O-benzyl-4,6-O-ꢀ2-naphthyl)-
methylene-b-d-galactopyranoside ꢀ23). Compound 20
was converted by method B to give 23 194.2%) as white
needles, mp 213±2158C 1from EtOAc), [a]Dˆ176.75 1c
0.45, chloroform); nmax 1KBr) 3458, 2860, 1402, 1388,
1180, 1114, 1062, 822, 696, 476 cm21; Anal. calcd for
C32H32O6: C 74.98, H 6.29. Found: C 74.84, H 6.23.
1
2178C, [a]Dˆ135.61 1c 0.40, chloroform). H NMR d
1500 MHz, CDCl3) 8.10±7.80 117H, m, aromatic); 13C
NMR d 1125 MHz, CDCl3) 134.3, 133.6 1Cq, aromatic),
133.3, 133.0 1CH, aromatic), 132.81C , aromatic), 130.0,
q
129.7, 129.0 1Cq, aromatic), 128.4, 128.3, 128.2, 128.0,
127.6, 126.3, 126.0, 125.7, 123.7 1CH, aromatic); nmax
1KBr) 2974, 2966, 2930, 1728, 1600, 1450, 1276, 1098,
1026, 806, 714, 486 cm21; MALDI-TOF measurment for
C32H28O8: 563.02 [M1Na]1, calcd: 563.17.
3.7.16. p-Methoxyphenyl 2,3-di-O-benzyl-4,6-O-ꢀ2-naph-
thyl)methylene-b-d-galactopyranoside ꢀ24). Compound
21 was converted by method B to give 24 190.6%) as
white needles, mp 204±2068C 1from EtOAc), [a]Dˆ
21.181 c 0.50, chloroform); nmax 1KBr) 3440, 3030, 1630,
1508, 1226, 1066, 1028, 824, 736, 478 cm21; MALDI-TOF
measurment for C38H36O7: 627.08, calcd: 627.24.
3.7.9. Ethyl 3-O-allyl-2-deoxy-4,6-O-ꢀ2-naphthyl)methyl-
ene-2-phthalimido-1-thio-b-d-gluco-pyranoside
ꢀ14).
Compound 10 was converted by method B using allyl
bromide as the reagent to give 14 188.3% after column
chromatography in hexane/EtOAc, 7:3) as a colourless
syrup, [a]Dˆ25.49 1c 0.50, chloroform). Anal. calcd for
C30H29O6NS: C 67.78, H 5.50, N 2.63, S 6.03. Found: C
67.91, H 5.51, N 2.68, S: 6.05.
3.7.17. Methyl 2,3-di-O-acetyl-4,6-O-ꢀ2-naphthyl)methyl-
ene-a-d-galactopyranoside ꢀ25). To a stirred solution of
compound 19 1500 mg) in dry pyridine 12 ml), acetic anhy-
dride was added 11 ml). After usual work-up procedure the
crystalline residue was recrystallized from EtOAc±nhexane
to give 25 183%) as white crystals, mp 184±1868C, [a]Dˆ
1207.46 1c 0.35, chloroform); nmax 1KBr) 3458, 2938,
1744, 1370, 1246, 1176, 1050, 990, 866, 826, 776,
3.7.10. Ethyl 2-deoxy-3-O-ꢀp-methoxybenzyl)-4,6-O-ꢀ2-
naphthyl)methylene-2-phthalimido-1-thio-b-d-gluco-
pyranoside ꢀ15). Compound 4 was converted by method B
using p-methoxybenzyl chloride as the reagent to give 11
186.5%) as white needles, mp 131±1338C 1from EtOH),
[a]Dˆ149.09 1c 0.40, chloroform); nmax 1KBr) 3456,
2926, 1714, 1388, 1066, 720, 484 cm21; MALDI-TOF
measurment for C35H33O7NS: 634.13 [M1Na]1, calcd:
634.18.
482 cm21
;
MALDI-TOF measurment for C22H24O8:
438.66 [M1Na]1, calcd: 439.13.
3.7.18. Methyl 2,3-di-O-benzyl-4-O-ꢀ2-naphthyl)methyl-
a-d-glucopyranoside ꢀ26). Compound 7 was converted by
method C to give 26 174%) as white needles, mp 68±738C
1from c-hexane), [a]Dˆ11.07 1c 0.37, chloroform). 1H
NMR d 1200 MHz, CDCl3) 7.85±7.20 117H, m, aromatic);
13C NMR d 150 MHz, CDCl3) 138.7, 138.0, 135.5 12£), 133.2,
132.9 1Cq, aromatic), 128.4±125.8 1CH, aromatic). Anal.
calcd for C32H34O6: C 74.69, H 6.66. Found: C 74.34, H 6.51.
3.7.11. Methyl 4,6-O-ꢀ2-naphthyl)methylene-a-d-galacto-
pyranoside ꢀ19). Compound 16 was converted by method A
to give 19 191.5%) as white solid, mp 179±1828C 1from
EtOH), [a]Dˆ199.46 1c 0.48, chloroform); nmax 1KBr)

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A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5731
3.7.19. Allyl 2,3-di-O-benzyl-4-O-ꢀ2-naphthyl)methyl-b-
d-glucopyranoside ꢀ27). Compound 11 was converted by
method C to give 27 179%) as white needles, mp 105±1088C
1from Et2O), [a]Dˆ220.581 c 0.19, chloroform). Anal.
calcd for C34H36O6: C 75.53, H 6.71. Found: C 75.14, H
6.67.
chloroform). Anal. calcd for C32H34O6: C 74.69, H 6.66.
Found: C 74.98, H 6.69.
3.7.28. Methyl 2,3-di-O-benzyl-4-O-ꢀ2-naphthyl)methyl-
b-d-galactopyranoside ꢀ36). Compound 23 was converted
by method C to give syrupy 36 171%), [a]Dˆ220.05 1c
0.37, chloroform). Anal. calcd for C32H34O6: C 74.69, H
6.66. Found: C 75.14, H 6.61.
3.7.20. p-Methoxyphenyl 2,3-di-O-benzyl-4-O-ꢀ2-naph-
thyl)methyl-b-d-glucopyranoside ꢀ28). Compound 12
was converted by method C to give 28 183%) as white
needles, mp 154±1558C 1from Et2O), [a]Dˆ219.23 1c
0.33, chloroform); nmax 1KBr) 3438, 2912, 1632, 1508,
1232, 1068, 820, 750, 734, 476 cm21; MALDI-TOF
measurment for C38H38O7: 629.09 [M1Na]1, calcd: 629.25.
3.7.29. p-Methoxyphenyl 2,3-di-O-benzyl-4-O-ꢀ2-naph-
thyl)methyl-b-d-galactopyranoside ꢀ37). Compound 24
was converted by method C to give 37 180%) as white
needles, mp 153±1558C 1from EtOAc±nhexane), [a]Dˆ
237.16 1c 0.26, chloroform); nmax 1KBr) 3384, 2870,
1508, 1228, 1084, 1058, 820, 744, 698, 476 cm21
;
MALDI-TOF measurment for C38H38O7: 629.11
3.7.21. Methyl 2,3-di-O-benzyl-6-O-ꢀ2-naphthyl)methyl-
a-d-glucopyranoside ꢀ29). Compound 7 was converted by
method D to give syrupy 29 171%), [a]Dˆ18.21 1c 0.53,
chloroform). 1H NMR d 1500 MHz, CDCl3) 7.85±7.20
117H, m, aromatic); 13C NMR d 1125 MHz, CDCl3)
138.7, 138.0, 135.4 12£), 133.1, 132.9 1Cq, aromatic),
128.5±125.5 1CH, aromatic). Anal. calcd for C32H34O6: C
74.69, H 6.66. Found: C 74.93, H 6.57.
[M1Na]1, calcd: 629.25.
3.7.30. Methyl 2,3-di-O-benzyl-6-O-ꢀ2-naphthyl)methyl-
a-d-galactopyranoside ꢀ38). Compound 22 was converted
by method D to give syrupy 38 164%), [a]Dˆ124.11 1c
0.81, chloroform). Anal. calcd for C32H34O6: C 74.69, H
6.66. Found: C 75.23, H 6.68.
3.7.22. Allyl 2,3-di-O-benzyl-6-O-ꢀ2-naphthyl)methyl-b-
d-glucopyranoside ꢀ30). Compound 11 was converted by
method D to give 30 179%) as white needles, mp 66±688C
1from EtOH), [a]Dˆ227.99 1c 0.18, chloroform). Anal.
calcd for C34H36O6: C 75.53, H 6.71. Found: C 75.97, H
6.68.
3.7.31. Methyl 2,3-di-O-benzyl-6-O-ꢀ2-naphthyl)methyl-
b-d-galactopyranoside ꢀ39). Compound 23 was converted
by method D to give syrupy 39 184%), [a]Dˆ0 1c 0.37,
chloroform). Anal. calcd for C32H34O6: C 74.69, H 6.66.
Found: C 74.14, H 6.62.
3.7.32. p-Methoxyphenyl 2,3-di-O-benzyl-6-O-ꢀ2-naph-
thyl)methyl-b-d-galactopyranoside ꢀ40). Compound 24
was converted by method D to give 40 167%) as white
needles, mp 86±888C 1from EtOH), [a]Dˆ26.39 1c 0.31,
chloroform); nmax 1KBr) 3446, 2910, 1506, 1364, 1216,
1096, 1062, 826, 740, 696, 474 cm21; MALDI-TOF
measurment for C38H38O7: 629.11 [M1Na]1, calcd: 629.25.
3.7.23. p-Methoxyphenyl 2,3-di-O-benzyl-6-O-ꢀ2-naph-
thyl)methyl-b-d-glucopyranoside ꢀ31). Compound 12
was converted by method D to give 31 183%) as white
needles, mp 119±1208C 1from EtOH), [a]Dˆ236.79 1c
0.55, chloroform); nmax 1KBr) 3474, 3060, 3024, 1506,
0384, 1230, 1086, 822, 754, 744 cm21; MALDI-TOF
measurment for C38H38O7: 629.08[M 1Na]1, calcd: 629.25.
3.7.33. p-Methoxyphenyl 2,3-di-O-benzyl-b-d-gluco-
pyranoside ꢀ41). Compound 12 was converted by method
E to give 41 179%) as white needles, mp 96±988C 1from
EtOH), [a]Dˆ225.03 1c 0.30, chloroform). Compound 41
was also prepared by method F, starting from 28 or 31,
respectively. Anal. calcd for C27H30O7: C 69.51, H 6.48.
Found: C 68.74, H 6.49.
3.7.24. Ethyl 3-O-allyl-2-deoxy-6-O-ꢀ2-naphthyl)methyl-
2-phthalimido-1-thio-b-d-glucopyranoside ꢀ32). Com-
pound 14 was converted by method D to give syrupy 32
178%), [a]Dˆ112.33 1c 0.83, chloroform). Anal. calcd for
C30H31O6NS: C 67.52, H 5.86, N 2.62, S 6.01. Found: C
67.47, H 5.88, N 2.60, S 6.08.
3.7.25. Ethyl 2-deoxy-3-O-ꢀp-methoxybenzyl)-6-O-ꢀ2-
naphthyl)methyl-2-phthalimido-1-thio-b-d-glucopyrano-
side ꢀ33). Compound 15 was converted by method D to
give syrupy 33 180%), [a]Dˆ141.33 1c 0.21, chloroform);
MALDI-TOF measurement for C35H35O7NS: 636.11
[M1Na]1, calcd: 636.23.
3.7.34. Ethyl 3-O-allyl-2-deoxy-2-phthalimido-1-thio-b-
d-glucopyranoside ꢀ42). Compound 14 was converted by
method E to give syrupy 42 183%), [a]Dˆ121.97 1c 3.54,
chloroform). Compound 42 was also prepared by method F,
starting from 32. Anal. calcd for C19H23O6NS: C 58.00,
H 5.89, N 3.56, S 8.15. Found: C 57.74, H 5.94, N 3.66, S
8.19.
3.7.26.
Methyl
2,3-di-O-benzoyl-6-O-ꢀ2-naphthyl)-
methyl-a-d-glucopyranoside ꢀ34). Compound 13 was
converted by method D to give syrupy 34 174%),
[a]Dˆ1109.95 1c 0.67, chloroform); MALDI-TOF
measurement for C32H30O8: 567.03, [M1Na]1, calcd:
567.19.
Acknowledgements
This reseach was supported by the Hungarian Scienti®c
Research Fund 1OTKA T 25244) and the Hungarian
Academy of Sciences 1AKP 2000-162 2,4). A. B. acknowl-
edges the Bolyai fellowship of the Hungarian Academy of
Sciences.
3.7.27. Methyl 2,3-di-O-benzyl-4-O-ꢀ2-naphthyl)methyl-
a-d-galactopyranoside ꢀ35). Compound 22 was converted
by method C to give syrupy 35 185%), [a]Dˆ23.95 1c 0.50,

Â
A. Borbas et al. / Tetrahedron 58 22002) 5723±5732
5732
   Â
23. Liptak, A.; Borbas, A.; Janossy, L.; Szilagyi, L. Tetrahedron
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