Alkylalanes and methyl furanosides: regioselective O-debenzylation or acetal cleavage

Article abstract of DOI:10.1016/j.carres.2006.05.002

Perbenzylated methyl pentofuranosides were submitted to the action of three alkylalanes and regioselective debenzylation at O-2 of the four pentoses was observed when choosing the right match between anomeric configuration and aluminium reagent. Diisobuty

Full text of DOI:10.1016/j.carres.2006.05.002

Carbohydrate Research 341 (2006) 2135–2144
Note
Alkylalanes and methyl furanosides: regioselective
O-debenzylation or acetal cleavage
Cai Jia,a,b,c Yongmin Zhang,a,b Li-He Zhang,c Pierre Sinaya,b and Matthieu Sollogouba,b,
*
¨
aEcole Normale Supe´rieure, De´partement de Chimie, UMR 8642 CNRS, 24 rue Lhomond, F-75005 Paris, France
bUniversite´ Pierre et Marie Curie-Paris 6, UMR 8642, Institut de Chimie Mole´culaire (FR 2769), Paris F-75005, France
cNational Research Laboratory of Natural and Biomimetic Drugs, Peking University, 38 Xueyuan Road,
Beijing 100083, Peoples’s Republic of China
Received 3 February 2006; received in revised form 25 April 2006; accepted 4 May 2006
Available online 30 May 2006
Abstract—Perbenzylated methyl pentofuranosides were submitted to the action of three alkylalanes and regioselective debenzylation
at O-2 of the four pentoses was observed when choosing the right match between anomeric configuration and aluminium reagent.
Diisobutylalane (DIBAL-H) allowed an easy access to reduced open-chain compounds, whereas trimethylalane (TMAL) stereo-
selectively produced methylated open chain derivatives.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: Furanose; Aluminium; Acetal cleavage; Regioselective deprotection
The regioselective access to a specific hydroxyl function
is an important target in carbohydrate chemistry,
usually achieved through protecting group manipula-
tion. Among them, the benzyl group is particularly
appreciated due to both its stability and to the mildness
of its cleavage. Various strategies have thus been deve-
loped to regioselectively introduce it, but the selective
debenzylation of easily obtainable polybenzylated com-
pounds is an interesting alternative option.1 In this con-
text, we have shown that isobutylalanes could be very
efficient agents of regioselective stripping of perbenzyl-
ated pyranosidic mono-, di- and even cyclic oligosaccha-
rides.2,3 We now report on the action of three
alkylalanes on the four possible anomeric pairs of per-
benzylated methyl D-pentofuranosides.
that both gave the products of selective O-debenzylation
at O-2, 18 and 23, respectively, in similar yields (48%).
Upon reaction with diisobutylalane (DIBAL-H), almost
all furanosidic compounds (1, 7, 9, 12, 14, 20 and 22)
gave the endocyclic reductive cleavage of the acetal
functionality to afford the corresponding acyclic pro-
ducts (2, 2, 10, 10, 15, 21, 24, respectively). The only
exception was the b-D-lyxofuranoside derivative 17
which gave a 1.1:1 mixture of 2-O and 3-O debenzylated
products 18 and 19 in 75% yield. In the course of our
studies on aluminium-promoted rearrangements, we
also showed that trimethylalane (TMAL) was able to
achieve an O-debenzylation reaction.4 We therefore sub-
mitted the four pairs of D-pentofuranoside anomers, to
the action of TMAL and two types of reactions
occurred: (i) selective debenzylation at O-2 of b-ribofur-
anoside (7), a-xylofuranoside (9), b-lyxofuranoside (17)
derivatives, or; (ii) stereoselective reductive cleavage of
b-xylo (12) and a-lyxo (14) compounds resulting in
methylated alditols.5 In the three other cases, a mixture
was obtained (Table 1).
When submitted to the action of triisobutylalane
(TIBAL), all methyl pentofuranosides gave a complex
mixture of compounds except for perbenzylated methyl
b-D-lyxofuranoside 17 and b-D-arabinofuranoside 22
*
Corresponding author. Fax: +33 1 44 32 33 97; e-mail: sollo@ens.fr
All methyl pentofuranosides were prepared by Fisher methanol
glycosylation followed by perbenzylation. The structures were
assigned by NMR spectroscopy according to Ref. 5.
Two reactions are therefore possible upon reac-
tion between pentofuranosides and alkylalanes: regio-
selective O-monodebenzylation and acetal cleavage.
0008-6215/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2006.05.002

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C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
Table 1. Reactions of perbenzylated methyl pentofuranosides with TIBAL, DIBAL-H and TMAL
Substrates
Reagents and conditions
Results
Entry
1
TIBAL (5 equiv), 60 °C, toluene, 20 h
Mixture
BnO
OMe
OMe
OH
DIBAL-H (5 equiv), 60 °C, toluene, 1 h, 65%
2
3
BnO
O
OBn OBn
2
OMe
OBn OBn
BnO
BnO
BnO
O
O
OH
15
TMAL (15 equiv), 50 °C, toluene, 20 h 43%
3/4 (1/3.8) 39% 5/6 (3.3/1)
OMe
OMe
OBn OBn
OBn OH
OH OBn
3,45
56
6
TIBAL (5 equiv), 60 °C, toluene, 80 h
Mixture
4
5
BnO
OMe
BnO
OH
OMe
O
DIBAL-H (6 equiv), 60 °C, toluene, 0.5 h, 60%
OBn OBn
2
OBn OBn
BnO
OMe
75
O
TMAL (15 equiv), 50 °C, toluene, 48 h, 38%
6
OBn OH
87
TIBAL (15 equiv), 60 °C, toluene, 2 h
Mixture
7
8
BnO
OH
OBn
OMe
BnO
O
OBn
DIBAL-H (5 equiv), 60 °C, toluene, 0.5 h, 72%
OBn
OMe
OBn
10
BnO
95
O
OBn
TMAL (15 equiv), 50 °C, toluene, 45 h, 40%
9
OMe
OH
115
TIBAL (5 equiv), 60 °C, toluene, 42 h
Mixture
10
11
BnO
OH
OBn
OMe
OMe
BnO
OMe
O
DIBAL-H (5 equiv), 60 °C, toluene, 1 h, 75%
OBn
OBn
OBn
10
BnO
OBn
125
OH
OBn
TMAL (15 equiv), 50 °C, toluene, 48 h, 50%
12
135

C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
2137
Table 1 (continued)
Substrates
Reagents and conditions
Results
Mixture
BnO
Entry
TIBAL (10 equiv), 60 °C, toluene, 12 h
13
OH
OBn
OBn
OMe
DIBAL-H (5 equiv), 60 °C, toluene, 15 min, 64%
14
BnO
15
O
BnO
OBn
BnO
O
OMe
OH
BnO
TMAL (15 equiv), 50 °C, toluene, 96 h, 50%
15
145
Me
16
BnO
BnO
BnO
OMe
OMe
OMe
O
OBn
TIBAL (5 equiv), 60 °C, toluene, 22 h, 48%
HO
HO
HO
16
17
18
18
BnO
BnO
OMe
OMe
O
O
O
OBn
OBn
OH
BnO
DIBAL-H (5 equiv), 60 °C, toluene, 4 h 75%,
18/19 (1.1/1)
BnO
18
19
175
O
OBn
TMAL (15 equiv), 50 °C, toluene, 96 h, 74%
18
TIBAL (5 equiv), 60 °C, toluene, 18 h
Mixture
19
BnO
BnO
OH
BnO
OMe
O
BnO
DIBAL-H (10 equiv), 60 °C, toluene, 15 h, 36%
TMAL (15 equiv), 50 °C, toluene, 42 h
20
21
OMe
OBn
21
OBn
205
Mixture
BnO
OMe
O
HO
TIBAL (15 equiv), 60 °C, toluene, 22 h, 48%
22
OBn
BnO
23
BnO
OMe
O
OH
BnO
BnO
OH
DIBAL-H (5 equiv), 60 °C, toluene, 1 h, 31%
TMAL (15 equiv), 50 °C, toluene, 60 h
23
24
OBn
OBn
225
24
Mixture

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C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
BnO BnO
BnO
BnO
BnO
O
OBn
O
OBn
O
OBn
O
OBn
O
OBn
AlR3
AlR3
H2O
OMe
OBn
OMe
OMe
OMe
AlR2
OMe
OH
BnO
BnO
O
AlR3
AlR3
9
11
R3Al
R3Al
Scheme 1. Proposed mechanism for aluminium induced deprotection.
BnO
AlR3
O
R2Al
O
R
AlR2
BnO
BnO
BnO
BnO
H2O
R
O
OBn
R
O
OBn
OH
OBn
OMe
OMe
AlR3
AlR3
OMe
OBn
OBn
OMe
OBn
OMe
OBn
BnO
OBn
OBn
9
10 R=H
13 R=Me
Scheme 2. Proposed mechanism for endocleavage.
A noticeable difference in reactivity was observed with
BnO
H
the lyxo derivative 14. Upon reaction with TMAL the
C-glycosyl derivative 16 was formed, probably via exo-
cleavage and nucleophilic methylation of the transient
carbenium. Absolute configuration at C-5 of 16 was
assigned from NOESY experiment (Fig. 1).
1
H
O
2
5
OH
BnO
6
4
3
H
Me
H
H
Finally, it should be stressed that compound 22, when
reacted with DIBAL-H, results in the open chain com-
pound 24 with loss of a methyl group. It is likely that
this compound is formed via O-demethylation followed
by reduction, because no further deacetalation product
is observed in all other ring opening cases.
This systematic study of the reactivity of perbenzyl-
ated methyl pentofuranosides with three alkylalanes
shows that it is possible to regioselectively O-debenzy-
late the four pentoses at O-2 when choosing the right
match between anomeric configuration and aluminium
reagent. DIBAL-H allows an easy access to open-chain
compounds and TMAL can stereoselectively produce
methylated open chain derivatives.
Figure 1. NOESY correlations for compound 16.
Regioselective deprotection of benzyl groups, or their
derivatives, has been reported on furanosides but often
in particular cases.8 Alkylalanes allow the access at
O-2 of ribo, xylo, lyxo and arabino derivatives (entries
6, 9, 16–18 and 22). As previously proposed a vicinal-cis
di-oxygenated pattern seems to be necessary for the de-
benzylation to occur, although the regioselectivity
appears to be more difficult to explain in the case of
furanosides compared to pyranosides. As recently pro-
posed by us,2 this O-dealkylation would start with the
formation of a penta-coordinated complex between the
aluminium reagent and the 1,2-cis oxygen pattern of
the sugar. A second aluminium atom would then select
the less hindered oxygen atom and direct the O-dealkyl-
ation. In the case of TIBAL and DIBAL-H, a molecule
of toluene is probably formed, whereas the reaction with
TMAL might lead to ethylbenzene (Scheme 1).
The deprotection reaction is in competition with
Lewis acid induced endocyclic cleavage of furanosides.9
When DIBAL-H is used, a reduced compound is
obtained through complexation of the endocyclic oxygen
and hydride transfer. The same mechanism applies to
TMAL with stereoselective methyl addition, the config-
uration of the formed stereogenic centres has not been
assigned (Scheme 2).
1. Experimental
1.1. General
Optical rotations were measured at 20 2 °C with a
Perkin–Elmer Model 241 digital polarimeter, using a
10 cm, 1 mL cell. Mass spectra (CI (ammonia) and
1
FAB) were obtained with a JMS-700 spectrometer. H
NMR spectra were recorded with a Bruker DRX 400
for solns in CDCl3 at ambient temperature. Assignments
were confirmed by COSY experiments. 13C NMR spec-
tra were recorded at 100.6 MHz with a Bruker DRX 400
spectrometer for solns in CDCl3 adopting 77.00 ppm for

C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
2139
the central line of CDCl3. Assignments were confirmed
by J-mode technique and HMQC. Reactions were mon-
itored by thin-layer chromatography (TLC) on a pre-
coated plate of Silica Gel 60 F254 (layer thickness
0.2 mm; E. Merck, Darmstadt, Germany) and detection
by charring with H2SO4. Flash column chromatography
was performed on Silica Gel 60 (230–400 mesh, E.
Merck). DIBAL-H, TIBAL and TMAL were purchased
from Aldrich as 1.5, 1 and 2 M solns in toluene,
respectively.
extracted with DCM and the organic layers were com-
bined, dried and concentrated. The resulting residue
was submitted to a flash column chromatography
(8:1–5:1, cyclohexane–EtOAc) to afford the acyclic com-
pound 3 (5 mg, 0.011 mmol, 9%), its isomer 4 (19 mg,
0.042 mmol, 34%), alcohol 5 (13 mg, 0.038 mmol, 30%)
and its regioisomer 6 (4 mg, 0.012 mmol, 9%).
1.3.1. 3,4,6-Tri-O-benzyl-1-deoxy-2-O-methyl-D-allitol or
20
altritol (3). ½aꢀD +20 (c 0.4, CHCl3); 1H NMR
(400 MHz, CDCl3): d 7.38–7.30 (m, 15H, H-arom.),
4.74 (d, 1H, J 11.5 Hz, CHPh), 4.70 (d, 1H, J 11.5 Hz,
CHPh), 4.69 (d, 1H, J 11.4 Hz, CHPh), 4.61 (d, 1H, J
11.4 Hz, CHPh), 4.59 (d, 1H, J 12.0 Hz, CHPh), 4.55
(d, 1H, J 12.0 Hz, CHPh), 4.12–4.07 (m, 1H, H-5),
3.77–3.72 (m, 2H, H-4, H-3), 3.71–3.62 (m, 3H, 2H-6,
H-2), 3.23 (d, 1H, JOH,5 3.6 Hz, 5-OH), 1.25 (d, 3H,
J1,2 6.0 Hz, 3H-1); 13C NMR (100 MHz, CDCl3): d
138.3, 138.26, 138.1 (3C-quat. arom.), 128.4–127.6
(15C-arom.), 81.5 (C-3), 78.9 (C-4), 77.2 (C-2), 73.5
(CH2Ph), 73.4 (CH2Ph), 73.3 (CH2Ph), 71.3 (C-6), 71.2
(C-5), 56.6 (OCH3), 15.1 (C-1); HRCIMS: Calcd for
C28H35O5 (M+H)+: 451.2484. Found: m/z 451.2480.
1.2. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-ribo-
furanoside (1) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 1
(0.23 g, 0.53 mmol) in dry toluene (0.9 mL), a soln of
DIBAL-H in toluene (1.8 mL, 2.7 mmol, 1.5 M) was
added at room temperature under argon. The reaction
mixture was heated at 60 °C for 1 h. When TLC indi-
cated the presence of a major product, the reaction
was carefully quenched with toluene saturated with
water and then aq NaOH (10%) was added at 0 °C.
The products were extracted with DCM and the organic
layers were combined, dried and concentrated. The
resulting residue was submitted to flash column chroma-
tography (4:1, cyclohexane–EtOAc) to afford 2 (0.15 g,
0.34 mmol, 65%).
1.3.2. 3,4,6-Tri-O-benzyl-1-deoxy-2-O-methyl-D-allitol or
20
altritol (4). ½aꢀD +17 (c 0.9, CHCl3); 1H NMR
(400 MHz, CDCl3): d 7.38–7.30 (m, 15H, H-arom.),
4.77 (d, 1H, J 11.5 Hz, CHPh), 4.72 (d, 1H, J 11.5 Hz,
CHPh), 4.66 (d, 1H, J 11.3 Hz, CHPh), 4.62 (d, 1H, J
11.3 Hz, CHPh), 4.59 (d, 1H, J 11.7 Hz, CHPh), 4.55
(d, 1H, J 11.7 Hz, CHPh), 4.19 (m, 1H, H-2), 3.82 (d,
1H, J3,5 6.3, J3,4 4.1 Hz, H-4), 3.74 (dd, 1H, J6,5 3.0,
1.2.1.
2,3,5-Tri-O-benzyl-1-O-methyl-D-ribitol
(2).
20
1
½aꢀD +10 (c 1.0, CHCl3); H NMR (400 MHz, CDCl3):
d 7.39–7.29 (m, 15H, H-arom.), 4.78 (d, 1H, J 11.8 Hz,
CHPh), 4.75 (d, 1H, J 11.3 Hz, CHPh), 4.66 (d, 1H, J
11.8 Hz, CHPh), 4.62 (d, 1H, J 11.3 Hz, CHPh), 4.59
(d, 1H, J 12.0 Hz, CHPh), 4.55 (d, 1H, J 12.0 Hz,
CHPh), 4.04 (m, 1H, H-2), 3.95 (q, 1H, J 4.4 Hz, H-
4), 3.81 (dd, 1H, J3,4 4.2, J3,2 6.9 Hz, H-3), 3.77 (dd,
1H, J5,4 4.2, J5,5 10.3 Hz, H-5), 3.68–3.61 (m, 3H, H-5,
2H-1), 3.41 (s, 3H, OCH3), 2.92 (d, 1H, J 4.4 Hz, 4-
OH); 13C NMR (100 MHz, CDCl3): d 138.33, 138.31,
138.0 (3C-quat. arom.), 128.4–127.6 (15C-arom.), 79.0
(C-3), 78.7 (C-4), 73.8 (CH2Ph), 73.4 (CH2Ph), 72.4
(CH2Ph), 71.8 (C-5), 71.2 (C-1), 70.9 (C-2), 59.1
(OMe); HRCIMS: Calcd for C27H36O5N [M+NH4]+:
454.2594. Found: m/z 454.2601.
0
0
0
J6,6 9.8 Hz, H-6), 3.70 (dd, 1H, J6 ,5 6.2, J6 ,6 9.8 Hz,
H-60), 3.68–3.64 (m, 2H, H-3, H-2), 3.40 (s, 3H,
OCH3), 3.17 (d, 1H, JOH,5 3.5 Hz, 5-OH), 1.25 (d, 3H,
J1,2 6.2 Hz, 3H-1); 13C NMR (100 MHz, CDCl3): d
138.34, 138.28, 138.2 (3C-quat. arom.), 128.4–127.6
(15C-arom.), 82.6 (C-3), 80.0 (C-4), 77.4 (C-2), 74.4
(CH2Ph), 73.4 (CH2Ph), 73.3 (CH2Ph), 71.4 (C-6), 71.0
(C-5), 56.9 (OCH3), 15.8 (C-1); HRCIMS: Calcd for
C28H35O5 (M+H)+: 451.2484. Found: m/z 451.2483.
1.3.3. Methyl 3,5-di-O-benzyl-a-D-ribofuranoside (5).
20
20
D
1
½aꢀD +72 (c 0.8, CHCl3), lit.6 ½aꢀ +67 (c 1, CHCl3); H
NMR (400 MHz, CDCl3): d 7.38–7.29 (m, 10H, H-
arom.), 4.93 (d, 1H, J1,2 4.7 Hz, H-1), 4.77 (d, 1H, J
12.4 Hz, CHPh), 4.62 (d, 1H, J 12.4 Hz, CHPh), 4.55
(d, 1H, J 12.1 Hz, CHPh), 4.49 (d, 1H, J 12.1 Hz,
CHPh), 4.20 (q, 1H, J4,3 3.2, J4,5 4.0 Hz, H-4), 4.16
(ddd, 1H, J2,OH 11.2, J2,1 4.8, J2,3 7.2 Hz, H-2), 3.83
(dd, 1H, J3,2 7.2, J3,4 3.2 Hz, H-3), 3.52 (s, 3H,
1.3. Reaction of methyl 2,3,4-tri-O-benzyl-a-D-ribo-
furanoside (1) with TMAL
To a soln of the perbenzylated furanoside 1 (54 mg,
0.12 mmol) in dry toluene (0.8 mL), a soln of TMAL
in toluene (0.96 mL, 1.92 mmol, 2 M) was added at
room temperature under argon. The reaction mixture
was heated at 60 °C for 20 h. When TLC indicated the
presence of major products, the reaction was carefully
quenched with toluene saturated with water and then
aq NaOH (10%) was added at 0 °C. The products were
0
OCH3), 3.48 (dd, 1H, J5,4 4.0, J5,5 10.3 Hz, H-5), 3.40
(dd, 1H, J5 ,4 4.0, J5 ,5 10.3 Hz, H-50), 2.99 (d, 1H,
JOH,2 11.2 Hz, 2-OH); 13C NMR (100 MHz, CDCl3): d
137.85, 137.8 (2C-quat. arom.), 128.6–127.6 (10C-
arom.), 103.0 (C-1), 82.0 (C-4), 76.3 (C-3), 73.5
0
0

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C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
(CH2Ph), 73.0 (CH2Ph), 71.8 (C-2), 70.0 (C-5), 55.7
(OCH3); HRCIMS: Calcd for C20H28O5N (M+NH4)+:
362.1968. Found: m/z 362.1973.
H-arom.), 4.91 (s, 1H, H-1), 4.62 (s, 4H, 2CH2Ph),
0
4.28 (q, 1H, J4,3 = J4,5 = J4,5 5.6 Hz, H-4), 4.12 (dd,
1H, J3,2 4.9, J3.4 6.2 Hz, H-3), 4.08–4.06 (m, 1H, H-2),
0
3.588 (d, 1H, J5,4 5.1 Hz, H-5), 3.587 (d, 1H, J5 ,4
1.3.4. Methyl 2,5-di-O-benzyl-a-D-ribofuranoside (6).
5.8 Hz, H-50), 3.36 (s, 3H, OCH3), 2.76 (d, 1H, JOH,2
3.2 Hz, 2-OH); 13C NMR (100 MHz, CDCl3): d 138.1,
137.0 (2C-quat. arom.), 128.4–127.6 (10C-arom.),
108.5 (C-1), 80.5 (C-4), 79.5 (C-3), 73.3 (C-2), 73.2
(CH2Ph), 72.7 (CH2Ph), 71.6 (C-5), 55.0 (OCH3).
FABMS: calcd 344.2 for C20H24O5. Found: m/z 367.2
(M+Na)+.
20
1
½aꢀD +30 (c 0.4, CHCl3); H NMR (400 MHz, CDCl3):
d 7.39–7.30 (m, 10H, H-arom.), 4.95 (d, 1H, J1,2
4.1 Hz, H-1), 4.79 (d, 1H, J 11.9 Hz, CHPh), 4.65 (d,
1H, J 11.9 Hz, CHPh), 4.59 (d, 1H, J 12.2 Hz, CHPh),
4.52 (d, 1H, J 12.2 Hz, CHPh), 4.30 (dt, 1H, J3,4 1.9,
J4,5 3.6 Hz, H-4), 4.10 (ddd, 1H, J3,4 1.9, J3,2 6.0,
J3,OH 8.9 Hz, H-3), 3.95 (dd, 1H, J2,1 4.1, J2,3 6.0 Hz,
H-2), 3.60 (d, 2H, J5,4 3.7 Hz, 2H-5), 3.47 (s, 3H,
OCH3), 3.06 (d, 1H, JOH,3 8.9 Hz, 3-OH); 13C NMR
(100 MHz, CDCl3): d 137.9, 137.2 (2C-quat. arom.),
128.5–127.5 (10C-arom.), 102.6 (C-1), 85.5 (C-4), 77.1
(C-2), 73.5 (CH2Ph), 72.3 (CH2Ph), 70.2 (C-5), 70.0
(C-3), 55.1 (OCH3); HRCIMS: Calcd for C20H28O5N
[M+NH4]+: 362.1968. Found: m/z 362.1973.
1.6. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-xylo-
furanoside (9) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 9
(0.10 g, 0.24 mmol) in dry toluene (1 mL), a soln of DI-
BAL-H in toluene (0.79 mL, 1.2 mmol, 1.5 M) was
added at room temperature under argon. The reaction
mixture was heated at 60 °C for 0.5 h. When TLC indi-
cated the presence of a major product, the reaction was
carefully quenched with aq NaOH (10%) at 0 °C. The
products were extracted with DCM and the organic lay-
ers were combined, dried and concentrated. The resul-
1.4. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-ribo-
furanoside (7) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 7
(0.3 g, 0.69 mmol) in dry toluene (3 mL), a soln of DI-
BAL-H in toluene (2.7 mL, 4.1 mmol, 1.5 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 0.5 h. When TLC indicated the
presence of a major product, the reaction was carefully
quenched with aq NaOH (10%) at 0 °C. The products
were extracted with DCM and the organic layers were
combined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (4:1,
cyclohexane–EtOAc) to afford 2 (0.18 g, 0.41 mmol,
60%).
tant residue was submitted to
a flash column
chromatography (5:1, cyclohexane–EtOAc) to afford
product 10 (75 mg, 0.17 mmol, 72%).
20
1.6.1. 2,3,5-Tri-O-benzyl-1-O-methyl-D-xylitol (10). ½aꢀD
ꢁ6 (c 0.9, CHCl3); 1H NMR (400 MHz, CDCl3): d 7.40–
7.30 (m, 15H, H-arom.), 4.78 (d, 1H, J 11.4 Hz, CHPh),
4.76 (d, 1H, J 11.8 Hz, CHPh), 4.65 (d, 1H, J 11.8 Hz,
CHPh), 4.60 (d, 1H, J 11.4 Hz, CHPh), 4.56 (d, 1H, J
11.9 Hz, CHPh), 4.50 (d, 1H, J 11.9 Hz, CHPh), 4.05
(td, 1H, J2,3 2.5, J2,1 = J2,1 6.1 Hz, H-2), 3.85 (dt, 1H,
0
J4,3 5.9, J4;5 ¼ J4;5 4.4 Hz, H-4), 3.78 (dd, 1H, J3,4 5.9,
0
1.5. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-ribo-
furanoside (7) with TMAL
J3,2 2.5 Hz, H-3), 3.68 (dd, 1H, J5,4 4.4, J5;5 10.6 Hz,
H-5), 3.65 (dd, 1H, J5 ;4 4.4, J5 ;5 10.6 Hz, H-50), 3.55
(dd, 1H, J1,2 6.3, J1,1 9.4 Hz, H-1), 3.49 (dd, 1H, J1,2
6.0, J1,1 9.4 Hz, H-1), 3.41 (s, 3H, OCH3); 13C NMR
(100 MHz, CDCl3): d 138.3, 138.1, 138.0 (3C-quat.
arom.), 128.3–127.6 (15C-arom.), 78.6 (C-4), 78.0 (C-3),
74.5 (CH2Ph), 73.2 (CH2Ph), 72.8 (CH2Ph), 71.9 (C-5),
71.2 (C-1), 69.4 (C-2), 59.2 (OMe); HRCIMS: Calcd
for C27H36O5N [M+NH4]+: 454.2594. Found: m/z
454.2586.
0
0
To a soln of the perbenzylated furanoside derivative 7
(143 mg, 0.33 mmol) in dry toluene (7 mL), a soln of
TMAL in toluene (3.5 mL, 7.0 mmol, 2 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 48 h. When TLC indicated the
presence of a major product, the reaction was carefully
quenched with toluene saturated with water and then
aq NaOH (10%) was added at 0 °C. The products were
extracted with DCM and the organic layers were
combined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (4:1,
cyclohexane–EtOAc) to afford 8 (43 mg, 0.13 mmol,
38%).
1.7. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-xylo-
furanoside (9) with TMAL
To a soln of the perbenzylated furanoside derivative 9
(110 mg, 0.25 mmol) in dry toluene (1.5 mL), a soln of
TMAL in toluene (0.70 mL, 1.4 mmol, 2 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 45 h. When TLC indicated the
presence of a major product, the reaction was carefully
1.5.1. Methyl 3,5-di-O-benzyl-b-D-ribofuranoside (8).
20
20
D
½aꢀD ꢁ20 (c 1.0, CHCl3), lit.7 ½aꢀ ꢁ23 (c 0.5, CHCl3);
1H NMR (400 MHz, CDCl3): d 7.39–7.30 (m, 10H,

C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
2141
quenched with toluene saturated with water and then aq
NaOH (10%) was added at 0 °C. The products were
extracted with DCM and the organic layers were
combined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (5:1,
cyclohexane–EtOAc) to afford 11 (34 mg, 0.10 mmol,
40%).
cyclohexane–EtOAc) to afford 13 (27 mg, 0.06 mmol,
50%).
1.9.1. 3,4,6-Tri-O-benzyl-1-deoxy-2-O-methyl-D-gulitol
20
or iditol (13). ½aꢀD ꢁ17 (c 0.6, CHCl3); 1H NMR
(400 MHz, CDCl3): d 7.38–7.28 (m, 15H, H-arom.),
4.81 (d, 1H, J 11.3 Hz, CHPh), 4.78 (d, 1H, J 11.3 Hz,
CHPh), 4.70 (d, 1H, J 11.3 Hz, CHPh), 4.57 (d, 1H, J
11.3 Hz, CHPh), 4.54 (d, 1H, J 11.3 Hz, CHPh), 4.49
(d, 1H, J 11.3 Hz, CHPh), 3.95 (dq, 1H, J5,4 2.5,
1.7.1. Methyl 3,5-di-O-benzyl-a-D-xylofuranoside (11).
20
1
½aꢀD +65 (c 0.6, CHCl3); H NMR (400 MHz, CDCl3):
d 7.39–7.30 (m, 10H, H-arom.), 5.04 (d, 1H, J1,2
4.7 Hz, H-1), 4.78 (d, 1H, J 12.0 Hz, CHPh), 4.68
(d, 1H, J 12.1 Hz, CHPh), 4.60 (d, 1H, J 12.0 Hz,
CHPh), 4.58 (d, 1H, J 12.1 Hz, CHPh), 4.44 (dt,
0
J5,6 = J5,6 = J5,OH 6.3 Hz, H-5), 3.81 (dd, 1H, J4,3 6.4,
J3,2 4.3 Hz, H-3), 3.71 (dd, 1H, J4,5 2.5, J3,4 6.4 Hz, H-
4), 3.59 (dq, 1H, J2,3 4.3, J2,1 6.4 Hz, H-2), 3.55 (dd,
0
0
1H, J6,5 6.2, J6,6 9.3 Hz, H-6), 3.49 (dd, 1H, J6 ,5 6.3,
0
1H, J4,3 6.3, J4,5 4.2, J4,5 6.4 Hz, H-4), 4.31 (dt, 1H,
J6 ,6 9.3 Hz, H-60), 3.38 (s, 3H, OCH3), 2.79 (d, 1H,
0
J2,OH 7.4, J2,1 = J2,3 4.4 Hz, H-2), 4.05 (dd, 1H, J3,2
JOH,5 6.3 Hz, 5-OH), 1.31 (d, 3H, J1,2 6.3 Hz, 3H-1);
13C NMR (100 MHz, CDCl3): d 138.6, 138.3, 138.0
(3C-quat. arom.), 128.4–127.5 (15C-arom.), 81.5 (C-3),
79.0 (C-4), 77.9 (C-2), 74.9 (CH2Ph), 74.3 (CH2Ph),
73.3 (CH2Ph), 71.2 (C-6), 70.0 (C-5), 56.4 (OCH3),
14.9 (C-1); HRCIMS: Calcd for C28H35O5 [M+H]+:
451.2484. Found: m/z 451.2480.
0
4.1, J3.4 6.0 Hz, H-3), 3.78 (dd, 1H, J5,4 4.2, J5,5
0
0
10.6 Hz, H-5), 3.70 (dd, 1H, J5 ,4 6.7, J5 ,5 10.6 Hz,
H-50), 3.54 (s, 3H, OCH3), 2.65 (d, 1H, J2,OH 7.4 Hz,
2-OH); 13C NMR (100 MHz, CDCl3): d 138.2, 137.9
(2C-quat. arom.), 128.3–127.5 (10C-arom.), 101.7
(C-1), 83.5 (C-3), 77.3 (C-4), 76.9 (C-2), 73.4 (CH2Ph),
71.8 (CH2Ph), 69.0 (C-5), 55.7 (OCH3); HRCIMS:
Calcd for C20H25O5 [M+H]+: 345.1702. Found: m/z
345.1701.
1.10. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-lyxo-
furanoside (14) with DIBAL-H
1.8. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-xylo-
furanoside (12) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 14
(138 mg, 0.32 mmol) in dry toluene (0.6 mL), a soln of
DIBAL-H in toluene (1.23 mL, 1.8 mmol, 1.5 M) was
added at room temperature under argon. The reaction
mixture was heated at 60 °C for 15 min. When TLC
indicated the presence of a major product, the reaction
was carefully quenched with aq NaOH (10%) at 0 °C.
The products were extracted with DCM and the organic
layers were combined, dried and concentrated. The
resultant residue was submitted to a flash column chro-
matography (5:1–3:1, cyclohexane–EtOAc) to afford 15
(0.07 g, 0.16 mmol, 51%).
To a soln of the perbenzylated furanoside derivative 12
(0.23 g, 0.52 mmol) in dry toluene (1 mL), a soln of DI-
BAL-H in toluene (1.8 mL, 2.7 mmol, 1.5 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 1 h. When TLC indicated the
presence of a major product, the reaction was carefully
quenched with aq NaOH (10%) at 0 °C. The products
were extracted with DCM and the organic layers were
combined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (5:1,
cyclohexane–EtOAc) to afford 10 (0.17 g, 0.39 mmol,
75%).
1.10.1. 1,3,4-Tri-O-benzyl-5-O-methyl-D-arabinitol (15).
20
½aꢀD ꢁ16 (c 0.9, CHCl3); 1H NMR (400 MHz, CDCl3): d
7.38–7.30 (m, 15H, H-arom.), 4.86 (d, 1H, J 11.7 Hz,
CHPh), 4.71 (d, 1H, J 11.3 Hz, CHPh), 4.68 (d, 1H, J
11.7 Hz, CHPh), 4.56 (d, 1H, J 12.0 Hz, CHPh), 4.56
(d, 1H, J 11.3 Hz, CHPh), 4.51 (d, 1H, J 12.0 Hz, CHPh),
1.9. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-xyloside
(12) with TMAL
0
To a soln of the perbenzylated furanoside derivative 12
(53 mg, 0.12 mmol) in dry toluene (0.8 mL), a soln of
TMAL in toluene (0.92 mL, 1.84 mmol, 2 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 48 h. When TLC indicated the
presence of a major product, the reaction was carefully
quenched with toluene saturated with H2O and then
aqueous NaOH soln (10%) at 0 °C. The products were
extracted with DCM and the organic layers were com-
bined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (7:1,
4.09 (td, 1H, J4,3 2.2, J4;5 ¼ J4;5 6.0 Hz, H-4), 3.84 (dt,
0
1H, J2,3 6.3, J2;1 ¼ J2;1 3.6 Hz, H-2), 3.81 (dd, 1H, J3,4
0
2.4, J3,2 6.3 Hz, H-3), 3.69 (dd, 1H, J1,2 3.4, J1;1
0
0
10.3 Hz, H-1), 3.63 (dd, 1H, J1 ;2 4.2, J1;1 10.3 Hz, H-
10), 3.58 (dd, 1H, J5,4 6.1, J5;5 9.6 Hz, H-5), 3.53 (dd,
0
1H, J5 ;4 5.9, J5 ;5 9.6 Hz, H-50), 3.40 (s, 3H, OCH3); 13C
NMR (100 MHz, CDCl3): d 138.0 (3C-quat. arom.),
128.4–127.6 (15C-arom.), 78.3 (C-2), 77.3 (C-3), 73.9
(CH2Ph), 73.3 (CH2Ph), 72.6 (CH2Ph), 71.4 (C-1), 71.3
(C-5), 69.7 (C-4), 59.1 (OMe); HRCIMS: Calcd for
C27H32O5N [M+NH4]+: 454.2594. Found: m/z 454.2599.
0
0

2142
C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
1.11. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-lyxo-
furanoside (14) with TMAL
J2,1 = J2,3 = J2,OH 2.6 Hz, H-2), 3.86–3.85 (m, 2H, H-
0
3, H-4), 3.79 (dd, 1H, J5,4 4.7, J5,5 10.5 Hz, H-5), 3.60
(dd, 1H, J5 ,4 8.5, J5 ,5 10.5 Hz, H-50), 3.43 (s, 3H,
OCH3), 2.59 (d, 1H, J2,OH 2.3 Hz, 2-OH); 13C NMR
(100 MHz, CDCl3): d 138.3, 138.0 (2C-quat. arom.),
128.4–127.7 (10C-arom.), 100.5 (C-1), 78.6, 74.0 (C-3,
C-4), 72.9, 72.5 (2CH2Ph), 68.7 (C-2), 60.7 (C-5), 55.1
(OCH3); HRCIMS: Calcd for C20H28O5N [M+NH4]+:
362.1968. Found: m/z 362.1970.
0
0
To a soln of the perbenzylated furanoside derivative 14
(96 mg, 0.22 mmol) in dry toluene (1.3 mL), a soln of
TMAL in toluene (1.65 mL, 3.3 mmol, 2 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 96 h. When TLC indicated the
presence of major products, the reaction was carefully
quenched with toluene saturated with water and then
aq NaOH (10%) was added at 0 °C. The products were
extracted with DCM and the organic layers were com-
bined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (6:1,
cyclohexane–EtOAc) to afford 16 (36 mg, 0.10 mmol,
50%).
1.13. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-lyxo-
furanoside (17) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 17
(0.2 g, 0.46 mmol) in dry toluene (1.6 mL), a soln of DI-
BAL-H in toluene (1.6 mL, 2.4 mmol, 1.5 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 4 h. When TLC indicated the
presence of major products, the reaction was carefully
quenched with aq NaOH (10%) at 0 °C. The products
were extracted with DCM and the organic layers were
combined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography
(5:1–3:1, cyclohexane–EtOAc) to afford products 19
(32 mg, 0.073 mmol, 35%) and 18 (36 mg, 0.083 mmol,
40%).
1.11.1. 2,5-Anhydro-1,4-di-O-benzyl-6-deoxy-D-altritol
20
(16). ½aꢀD +41 (c 0.5, CHCl3); 1H NMR (400 MHz,
CDCl3): d 7.42–7.30 (m, 10H, H-arom.), 4.71 (d, 1H, J
11.7 Hz, CHPh), 4.67 (d, 1H, J 12.2 Hz, CHPh), 4.61
(d, 1H, J 11.7 Hz, CHPh), 4.60 (d, 1H, J 12.2 Hz,
0
CHPh), 4.30 (q, 1H, J 3.9 Hz, H-3), 4.23 (dt, 1H, J2,1
6.6, J2,3 = J2,1 4.3 Hz, H-2), 4.12 (dq, 1H, J5,4 7.5, J5,6
0
6.3 Hz, H-5), 3.83 (dd, 1H, J1,2 4.8, J1,1 10.0 Hz, H-1),
3.73 (dd, 1H, J1 ,2 6.5, J1 ,1 10.0 Hz, H-10), 3.66 (dd,
1H, J4,3 4.5, J4,5 7.5 Hz, H-4), 2.68 (d, 1H, JOH,3
3.3 Hz, 3-OH), 1.32 (d, 3H, J6,5 6.3 Hz, 3H-6); 13C
NMR (100 MHz, CDCl3): d 138.1, 137.2 (2C-quat.
arom.), 128.6–127.6 (10C-arom.), 85.1 (C-4), 79.2 (C-
2), 75.4 (C-5), 73.5 (CH2Ph), 72.6 (CH2Ph), 70.2 (C-3),
69.1 (C-1), 19.0 (C-6); HRCIMS: Calcd for
C20H28O4N [M+NH4]+: 346.2018. Found: m/z
346.2025.
0
0
1.13.1. Methyl 2,5-di-O-benzyl-b-D-lyxofuranoside (19).
20
1
½aꢀD +5 (c 0.9, CHCl3); H NMR (400 MHz, CDCl3): d
7.41–7.30 (m, 10H, H-arom.), 4.79 (d, 1H, J 11.8 Hz,
CHPh), 4.74 (d, 1H, J 11.9 Hz, CHPh), 4.69 (d, 1H, J
11.9 Hz, CHPh), 4.68 (d, 1H, J1,2 3.3 Hz, H-1), 4.67 (d,
1H, J 11.8 Hz, CHPh), 3.99 (ddd, 1H, J3,2 3.5, J3,OH
6.3, J3,4 7.8 Hz, H-3), 3.81–3.71 (m, 3H, H-2, H-4, H-
5), 3.58 (dd, 1H, J5,4 8.0, J5,5 10.8 Hz, H-5), 3.41 (s,
3H, OCH3), 2.46 (d, 1H, JOH,3 6.3 Hz, 3-OH); 13C
NMR (100 MHz, CDCl3): d 138.3, 137.9 (2C-quat.
arom.), 128.6–127.7 (10C-arom.), 99.2 (C-1), 77.6, 75.8
(C-2, C-4), 73.3 (CH2Ph), 72.6 (CH2Ph), 70.6 (C-3),
60.8 (C-5), 55.3 (OMe); HRCIMS: Calcd for
C20H28O5N [M+NH4]+: 362.1968. Found: m/z 362.1957.
1.12. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-lyxo-
furanoside (17) with TIBAL
A soln of TIBAL in toluene (2.4 mL, 2.4 mmol, 1 M)
was added to the perbenzylated furanoside derivative
17 (197 mg, 0.45 mmol) at room temperature under ar-
gon. The reaction mixture was heated at 60 °C for
22 h. When TLC indicated the presence of a major prod-
uct, the reaction was carefully quenched with ice-cold
water. The products were extracted with DCM and the
organic layers were combined, dried and concentrated.
The resultant residue was submitted to a flash column
chromatography (4:1, cyclohexane–EtOAc,) to afford
18 (75 mg, 0.22 mmol, 48%).
1.14. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-lyxo-
furanoside (17) with TMAL
To a soln of the perbenzylated furanoside derivative 17
(82 mg, 0.19 mmol) in dry toluene (1.2 mL), a soln of
TMAL in toluene (1.41 mL, 2.82 mmol, 2 M) was added
at room temperature under argon. The reaction mixture
was heated at 60 °C for 96 h. When TLC indicated the
presence of a major product, the reaction was carefully
quenched with toluene saturated with water and then
aq NaOH (10%) was added at 0 °C. The products were
extracted with DCM and the organic layers were com-
bined, dried and concentrated. The resultant residue
was submitted to a flash column chromatography (4:1,
1.12.1. Methyl 3,5-di-O-benzyl-b-D-lyxofuranoside (18).
20
½aꢀD +47 (c 0.7, CHCl3); 1H NMR (400 MHz, CDCl3): d
7.41–7.36 (m, 10H, H-arom.), 4.78 (d, 1H, J 11.6 Hz,
CHPh), 4.76 (d, 1H, J 10.3 Hz, CHPh), 4.74 (d, 1H, J
10.3 Hz, CHPh), 4.70 (d, 1H, J1,2 3.2 Hz, H-1), 4.68
(d, 1H,
J
11.6 Hz, CHPh), 4.00 (q, 1H,

C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
2143
cyclohexane–EtOAc) to afford 18 (48 mg, 0.14 mmol,
74%).
H-3), 3.58 (d, 2H J4,5 5.7 Hz, 2H-5), 3.46 (s, 3H,
OCH3), 2.65 (d, 1H, JOH,2 9.5 Hz, 2-OH); 13C NMR
(100 MHz, CDCl3): d 138.0, 137.9 (2C-quat. arom.),
128.3–127.6 (10C-arom.), 102.6 (C-1), 84.5 (C-3), 80.7
(C-4), 77.9 (C-2), 73.2 (CH2Ph), 72.0 (C-5), 71.8
(CH2Ph), 55.3 (OCH3); HRCIMS: Calcd for
C20H28O5N [M+NH4]+: 362.1968. Found: m/z
362.1971.
1.15. Reaction of methyl 2,3,5-tri-O-benzyl-a-D-arabino-
furanoside (20) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 20
(0.16 g, 0.37 mmol) in dry toluene (1.8 mL), a soln of
DIBAL-H in toluene (2.5 mL, 3.8 mmol, 1.5 M) was
added at room temperature under argon. The reaction
mixture was heated at 60 °C for 15 h. When TLC indi-
cated the presence of a major product, the reaction
was carefully quenched with aq NaOH (10%) at 0 °C.
The products were extracted with DCM and the organic
layers were combined, dried and concentrated. The
resultant residue was submitted to a flash column chro-
matography (5:1, cyclohexane–EtOAc) to afford 21
(57 mg, 0.13 mmol, 35%).
1.17. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-arabino-
furanoside (22) with DIBAL-H
To a soln of the perbenzylated furanoside derivative 22
(116 mg, 0.25 mmol) in dry toluene (1 mL), a soln of DI-
BAL-H in toluene (0.84 mL, 1.3 mmol, 1.5 M) was
added at room temperature under argon. The reaction
mixture was heated at 60 °C for 1 h. When TLC indi-
cated the presence of a major product, the reaction
was carefully quenched with aq NaOH (10%) at 0 °C.
The products were extracted with DCM and the organic
layers were combined, dried and concentrated. The
resultant residue was submitted to a flash column chro-
matography (3:1, cyclohexane–EtOAc) to afford 24
(35 mg, 0.083 mmol, 31%).
1.15.1. 2,3,5-Tri-O-benzyl-1-O-methyl-D-arabinitol (21).
20
1
½aꢀD +6 (c 1.3, CHCl3); H NMR (250 MHz, CDCl3): d
7.30–7.16 (m, 15H, H-arom.), 4.63 (d, 1H, J 11.6 Hz,
CHPh), 4.54 (d, 1H, J 11.6 Hz, CHPh), 4.47 (s, 2H,
CH2Ph), 4.44 (s, 2H, CH2Ph), 3.90 (m, 1H, H-2), 3.80
(m, 1H, H-4), 3.60 (dd, 1H, J 3.3, 7.5 Hz, H-3), 3.52
(m, 4H, 2 H-5, 2 H-1), 3.23 (s, 3H, OCH3), 2.85 (d,
1H, J 5.3 Hz, 4-OH); 13C NMR (62.5 MHz, CDCl3): d
138.2, 138.2, 138.1 (3C-quat. arom.), 128.6–127.0
(15C-arom.), 77.9, 77.7 (C-4, C-3), 73.8 (CH2Ph), 73.4
(CH2Ph), 73.2 (CH2Ph), 72.1 (C-5), 71.2 (C-1), 70.4
(C-2), 59.0 (OMe); HRCIMS: Calcd for C27H36O5N
[M+NH4]+: 454.2594. Found: m/z 454.2599.
20
1.17.1. 2,3,5-Tri-O-benzyl-D-arabinitol (24). ½aꢀD +2 (c
1
1.7, CHCl3); H NMR (400 MHz, CDCl3): d 7.41–7.30
(m, 15H, H-arom.), 4.70 (d, 1H, J 11.6 Hz, CHPh),
4.67 (d, 1H, J 11.6 Hz, CHPh), 4.66 (d, 1H, J 11.4 Hz,
CHPh), 4.62 (d, 1H, J 11.4 Hz, CHPh), 4.60 (d, 1H, J
11.9 Hz, CHPh), 4.57 (d, 1H, J 11.9 Hz, CHPh), 4.10–
4.05 (m, 1H, H-4), 3.88–3.75 (m, 4H, 2H-1, H-2, H-3),
0
3.71 (dd, 1H, J5,4 4.0, J5;5 9.8 Hz, H-5), 3.69 (dd, 1H,
0
0
1.16. Reaction of methyl 2,3,5-tri-O-benzyl-b-D-arabino-
furanoside (22) with TIBAL
J5 ;4 5.0, J5;5 9.8 Hz, H-50), 3.08 (d, 1H, JOH,4 5.2 Hz,
4-OH), 2.38 (br t, 1H, 1-OH); 13C NMR (100 MHz,
CDCl3): d 137.82, 137.80, 137.7 (3C-quat. arom.),
128.5–127.7 (15C-arom.), 79.3, 78.3 (C-2, C-3), 73.7
(CH2Ph), 73.4 (CH2Ph), 72.7 (CH2Ph), 70.9 (C-5), 70.4
(C-4), 61.4 (C-1); HRCIMS: Calcd for C26H34O5N
[M+NH4]+: 440.2437. Found: m/z 440.2442.
A soln of TIBAL in toluene (3.8 mL, 3.8 mmol, 1 M)
was added to the perbenzylated furanoside derivative
22 (0.11 g, 0.25 mmol) at room temperature under
argon. The reaction mixture was heated at 60 °C for
22 h. When TLC indicated the presence of a major prod-
uct, the reaction was carefully quenched with ice-cold
water. The products were extracted with DCM and the
organic layers were combined, dried and concentrated.
The resultant residue was submitted to a flash column
chromatography (5:1, cyclohexane–EtOAc) to afford
product 23 (42 mg, 0.12 mmol, 48%).
Acknowledgements
The authors thank Olivia Bistri, for her precious help,
the French Embassy in China, for joint Ph.D. fellow-
ship. (C.J.) The authors express their gratitude to one
of the referees for drawing our attention to the structure
of compound 16.
1.16.1. Methyl 3,5-di-O-benzyl-b-D-arabinofuranoside
20
(23). ½aꢀD ꢁ16 (c 1.0, CHCl3); 1H NMR (400 MHz,
CDCl3): d 7.40–7.30 (m, 10H, H-arom.), 4.91 (d, 1H,
J1,2 4.7 Hz, H-1), 4.80 (d, 1H, J 11.9 Hz, CHPh), 4.67
(d, 1H, J 11.9 Hz, CHPh), 4.64 (d, 1H, J 12.2 Hz,
CHPh), 4.60 (d, 1H, J 12.2 Hz, CHPh), 4.31 (ddd, 1H,
J2,1 4.7, J2,3 5.9, J2,OH 9.5 Hz, H-2), 4.19 (q, 1H,
J4,3 = J4,5 5.6 Hz, H-4), 3.90 (t, 1H, J3.2 = J3.4 5.8 Hz,
Supplementary data
Supplementary data associated with this article can be
found, in the online version, at doi:10.1016/j.carres.
2006.05.002.

2144
C. Jia et al. / Carbohydrate Research 341 (2006) 2135–2144
6. Su, T.-L.; Klein, R. S.; Fox, J. J. J. Org. Chem. 1982, 47,
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