Reaction of sugar allyltins with aldehydes. A remarkable difference in reactivity between furanose and pyranose organometallic derivatives

Article abstract of DOI:10.1016/S0957-4166(01)00331-7

The reaction of organometallic derivatives of monosaccharides with aldehydes catalyzed with BF₃·OEt₂ was studied. A significant difference in reactivity between the pyranosidic and furanosidic and allyltins was noted. The former reacted readily with aldehydes affording precursors of higher carbon sugars with very high stereoselectivity, while the latter underwent rearrangement with elimination of the stannyl moiety prior to reaction with the aldehyde.

Full text of DOI:10.1016/S0957-4166(01)00331-7

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 12 (2001) 1895–1905
Reaction of sugar allyltins with aldehydes. A remarkable
difference in reactivity between furanose and pyranose
organometallic derivatives
Sławomir Jarosz,a,* Stanisław Sko´ra,a Katarzyna Szewczyka and Zbigniew Ciunikb
aInstitute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44, 01-224 Warsaw, Poland
bFaculty of Chemistry, University of Wrocław, F. Joliot-Curie 14, 50-383 Wrocław, Poland
Received 30 June 2001; accepted 24 July 2001
Abstract—The reaction of organometallic derivatives of monosaccharides with aldehydes catalyzed with BF3·OEt2 was studied. A
significant difference in reactivity between the pyranosidic and furanosidic allyltins was noted. The former reacted readily with
aldehydes affording precursors of higher carbon sugars with very high stereoselectivity, while the latter underwent rearrangement
with elimination of the stannyl moiety prior to reaction with the aldehyde. © 2001 Elsevier Science Ltd. All rights reserved.
1. Introduction
We also applied the allyltin derivative 6 (which can be
prepared by a method depicted in Fig. 2) for construc-
tion of
a
higher sugar skeleton (Fig. 2).6 This
The synthesis of higher carbon sugars has gained con-
siderable attention in the last decade. Such compounds
may serve as non-metabolized analogs of sugars and
may be used for the specific complexation of inorganic
as well as organic cations (enantioselective complexa-
tion) or for studying conformational features. A num-
ber of methods leading to such molecules has been
developed.1
organometallic compound reacted with sugar aldehyde
7 leading to the unsaturated alcohol 9 in the titanium
chloride-catalyzed process. However, this reaction was
capricious and afforded mainly unsaturated aldehyde 8;
for acceptable yields of the condensation product, an
excess of the allyltin reagent had to be used.6
Although this decomposition process of allyltin deriva-
tives (which may be performed in a strictly controlled
manner7) opens a convenient route for the preparation
of chiral, highly oxygenated cyclopentanes,8 bicy-
clo[4.3.0]nonanes9 and bicyclo[4.4.0]decanes10 (Fig. 2),
the formation of the dienoaldehyde (being an undesired
side process) significantly lowers the yield of the higher
carbon sugar precursors.
In the past several years, we proposed a general
methodology for the preparation of higher carbon sug-
ars by coupling two sugar subunits2 (Fig. 1).
Sugar phosphoranes3 1, phosphonates4 2, or vinyltin
derivatives of monosaccharides5 4 were used as starting
materials for the preparation of precursors 3 which are
readily converted into higher carbon sugars2 5.
Figure 1. Methods for the preparation of higher carbon sugars.
* Corresponding author. E-mail: sljar@icho.edu.pl
0957-4166/01/$ - see front matter © 2001 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(01)00331-7

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S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
Figure 2. Preparation of sugar allyltins and their application in organic synthesis.
2. Results and discussion
The reaction of organostannane reagents with alde-
hydes catalyzed with a Lewis acid proceeds through a
different mechanism. The relatively low Lewis acidity of
the tin atom in organostannanes compared to that of
Lewis acids such as TiCl4, ZnBr2, AlCl3 and BF3,
means that the carbonyl group is complexed by these
Lewis acids but not tin. The open-chain model leading
to the same erythro isomer—regardless of the configu-
ration of starting allyltin—is, therefore, preferred14
(Fig. 3).
The reaction of the allyltin derivatives with aldehydes
can be performed either at high temperature,11 under
high pressure,12 under radical conditions,13 or may be
catalyzed with a Lewis acid.14 The relative configura-
tions of the products (homoallylic alcohols) in the
former two processes (Dt, Dp) depends on the geometry
of the double bond of the starting allyltin derivative. It
is, however, independent in an acid-catalyzed process.
The first two processes (Dt, Dp) proceed via a cyclic
six-membered transition state in which the tin atom
coordinates to a carbonyl group. It is evident, there-
fore, that both geometrical isomers must form different
homoallylic alcohols (Fig. 3).
Since sugar allyltin derivatives readily undergo decom-
position on treatment with TiCl4,6 optimization of the
conditions of the coupling process leading to a higher
carbon sugar skeleton is required. Also, the reactivity of
the pyranose- and furanose-derived organometallics
Figure 3. Stereochemical models for the reaction of allytins with aldehydes.

S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
1897
should be examined, since application of sugars with
different size of the ring would extend the usefulness of
the proposed method.
configuration at the C(7) center in 15 might be assigned
on the basis of the CD spectroscopy,17 while the relative
stereochemistry between the C(6) and C(7) centers could
be established from NMR experiments performed on a
cyclic derivative (e.g. 16), which could be prepared from
15 by standard methods.
2.1. Reaction of the pyranose allyltins with aldehyde
Reaction of methyl 2,3,4-tri-O-benzyl-6,7,8-trideoxy-8-
tributylstannyl-oct-6-eno-a-
pyranosides7 (6 in Scheme 1 or 10 in Scheme 2) with
2,3:4,5-di-O-isopropylidene-
-arabinose15 11 either at
D
-gluco- or
D
-manno-1,5-
For the temporary protection of the hydroxyl group in
12 the allyl ether blocking group was chosen. This was
basedonitsstabilityunderavarietyofreactionconditions
and the possibility of its selective removal.18 Fortunately,
protection of the C(7)-OH as an allyl ether provided a
crystalline derivative 13, the configuration of which was
determined by the X-ray analysis, thus avoiding a tedious
degradation sequence. The ORTEP drawing of 13 is
shown in Fig. 4.
D
high temperature (140°C, boiling xylene) or under high
pressure(11 kbar) did not provide the desired higher sugar
precursors; the starting materials remained unreacted.
These results showed unambiguously that the Lewis acid
is needed to promote the coupling of sugar allyltin
reagents with aldehydes. From several acids tested (SnCl4,
TiCl4, ZnBr2, AlCl3, BF3·OEt2), boron trifluoride ether-
ate was found to be the reagent of choice. Reaction of the
An explanation of this very high selectivity is shown in
Fig. 5. According to the model14 proposed for reaction of
allyltins with aldehydes catalyzed with a Lewis acid the
erythro adduct (see Fig. 3) is preferred regardless of the
configuration of the double bond of allyltin derivative.
The attack of the pre-complexed aldehyde 11 may occur
either ‘from the front’ or ‘from behind’ of the sugar ring
of 6 (transition states A leading to the (6R,7S) isomer or
B (“6S,7R) in Fig. 5). It can be clearly seen that attack
from ‘the front of the ring’ is much more preferable to
the alternative one, since in the transition state B severe
steric repulsion between the isopropylidene group of
aldehyde 11 and the allyltin fragment of 6 is noted. This
interaction is much stronger than the Coulombic repul-
sion between the carbonyl group and the ring oxygen
atom in approach B.
D
-gluco-configurated derivative 6 with aldehyde 11 in the
presence of BF3·OEt2 gave 81% of the coupling product
12 as a single stereoisomer (Scheme 1). No decomposition
of the allyltin derivative was seen using this promoter.
We assumed that, the configurations of the newly created
stereogenic centers at C(6) and C(7) should be easily
determined by the sequence of reactions shown in Scheme
1. Compound 12 could be converted into diol 15 by simple
transformations, involving temporary protection of the
free hydroxyl group at C(7), manipulations at the ‘right’
part of the molecule and finally deprotection. Diol 15
might be further converted into a known16 octoside 17,
thus assigning the geometry at the newly created stereo-
genic C(6) and C(7) centers. Alternatively, the absolute
Scheme 1. (i) BF3·OEt2, THF, −78°C, 81%; (ii) AllBr, NaH, DMF.
Scheme 2. (i) BF3·OEt2, THF, −78°C; (ii) (a) AllBr, NaH, DMF; (b) MeOH, H(+); (c) NaIO4, then NaBH4; (d) deallylation.

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S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
Figure 6. CD spectra of the molybdenum complexes of 19
(---) and 24 (––) in the preferred threo arrangement of the
hydroxy groups. The negative sign of the Cotton effect at ca.
315 nm points to the 7R configuration (see Ref. 17).
Figure 4. ORTEP dawing of compound 13.
of 19 pointed unambiguously to the (S)-configuration
at the C(7) center (see Fig. 6).
Reaction of either 6 or 10 ((R)-configured at C(5) a- to
the allyltin unit) with aldehyde 11 ((S)-configured a to
the carbonyl group) represents a case in which both
starting materials are chiral and may have influence on
the steric course of this coupling process. The question,
however, arises as to which component (allyltin or
aldehyde) is responsible for the stereochemical outcome
of the reaction. To solve this problem we performed the
reaction of chiral allyltin 10 with the simplest achiral
sugar-like derivative, O-tert-butyldiphenylsilyl glycol
aldehyde10b,19 20. The reaction of 10 with 20 catalyzed
with BF3·OEt2 afforded 21 in 26% yield and 22 in 49%
yield (Scheme 3).
The relative configurations of both compounds were—
as expected (see Fig. 3)—erythro, as determined by
chemical and spectral correlations. Both compounds
were deprotected with HF·py complex to the corre-
sponding diols 23 and 24. Compound 23 (obtained
from minor isomer 21) was identical to the previously
obtained diol 19, proving the (6R,7S)-configuration at
the newly created stereogenic centers in 21. Periodic
acid cleavage of the C(7)ꢀC(8) bond in 23 (=19) fol-
lowed by reduction of the resulting aldehyde afforded
alcohol 25. The same sequence of reactions performed
on 24 led to stereoisomer 26, thus proving the opposite
configuration at C(6) in 22. The (7R)-configuration in
the diol 24 was assigned on the basis of the CD spectra
its dimolybdenum complex (see Fig. 6).
Figure 5. Preferred (A) and disfavoured (B) transition states
in the reaction of 6 with aldehyde 11.
Reaction of the
D
-manno-configured allyltin reagent 10
with aldehyde 11 (under the same conditions as for 6
and 11) proceeded similarly, although the selectivity
was slightly lower. The results are summarized in
Scheme 2. Treatment of a mixture of 10 and 11 with
boron trifluoride etherate afforded 18 in 80% yield
together with small amounts of isomers 18% and 18%%. It
could be postulated that the configuration of the main
isomer 18 has to be the same as that of 12, because of
only slight difference (at the distant stereogenic center)
in the geometry of 6 and 10.
The selectivity of the coupling of the allyltin 10 with
achiral aldehyde 20 was not particularly high. More-
over, the opposite product (than that obtained in reac-
tion of 10 with the chiral aldehyde 11) predominated.
This means, that the chirality of the aldehyde (a-S in
11) is much more important for the stereochemical
outcome of the coupling than the chirality of the
allyltin derivative. The explanation is shown in Fig. 7.
This assumption was verified by the CD spectral assign-
ment performed for the degradation product 19 (for its
preparation, see Section 4). The positive Cotton effect
at ca. 315 nm observed for the dimolybdenum complex

S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
1899
Scheme 3. (i) BF3·OEt2, THF, −78°C; (ii) HF·py in MeOH; (iii) NaIO4, then NaBH4.
The attack of activated aldehyde is more favored from
‘behind the ring’ than from the ‘front’ of the sugar
allyltin, since in the latter there is an unfavorable
interaction between the complexed carbonyl and the
ring oxygen atom (Fig. 7). The differentiation of both
sides of the sugar ring is not, however, particularly high
and hence the selectivity of the coupling process is
relatively low.
spectrum of the main isomer only two isopropylidene
groups were seen (at l 110.9 and 109.5 ppm). Other
signals at l 136.0, 128.4, 127.8, 118.8 (ꢁCH2), 83.8,
78.5, 70.5, 27.4, and 26.7 ppm strongly resembled those
observed in the spectrum of compound 2920 obtained
from allyltin 27 by treatment with a Lewis acid in the
absence of aldehyde.
These data suggested that the allyltin derivative decom-
posed prior to the reaction with aldehyde and the
‘decomposed’ species 30 reacted with the carbonyl
group of 11 to give the disaccharide intermediate 31
(Scheme 4). Two possible pathways of stabilization of
31 (with the loss of the molecule of acetone) should be
considered:
Attack of the oxygen anion on the C(4) position
(what is connected with the inversion of the configu-
ration at this tertiary center) leading to disaccharide
32 with a five-membered ring.
2.2. Reaction of furanose allyltins with aldehyde
Reaction of the furanose-derived allyltins with alde-
hydes catalyzed with a Lewis acid proceeded via a
completely different pathway. Treatment of 3-O-benzyl-
1,2-O-isopropylidene-5,6,7-trideoxy-7-tributylstannyl-
hept-5-ene-a-
-ribo-1,4-furanose7 27 and aldehyde 11
D
with boron trifluoride etherate did not afford the
expected product 28, but a mixture of two compounds†
with the molecular formula C25H34O8, strongly suggest-
ing the loss of a molecule of acetone. In the 13C NMR
Attack of the oxygen anion on the C(5) position
leading to disaccharide 33 containing a six-membered
ring.
It is not easy to choose between those pathways analyz-
ing only the NMR spectra of the products, however,
the structures of the products (i.e. the size of the newly
formed ring) can be unequivocally assigned by chemical
correlations. Hydrolysis of the glycosydic linkage (with
simultaneous removal of the isopropylidene groups)
followed by reduction with NaBH4 and acetylation
should afford either penta-O-acetyl-xylitol21 (34; from
32) or penta-O-acetyl-
D
-arabinitol21 (35; from 33). Both
model compounds are readily distinguishable by the 13
C
NMR spectroscopy; only three signals of the pentitol
chain were observed in the spectrum of xylitol 34 (at l
61.8 (C-1,5), 69.04 (C-2,4), and 68.98 (C-3) ppm) and
five signals for arabinitol 35 (at l 61.6, 61.9 (C-1,5),
67.92, 67.97, and 68.23 (C-2,4,3) ppm).
Figure 7. Preferred (B) and disfavoured (A) transition states
in the reaction of 6 with aldehyde 20.
In the spectrum of the product obtained by degradation
of both isomers resulting from the coupling of 27 with
11 we were able to detect only the corresponding
signals of the arabinitol 37; no signals of xylitol 34 were
seen. These results proved the structure 33 and
† Both compounds obtained in this reaction had similar NMR spectra
suggesting that they were isomers.

1900
S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
Scheme 4. (i) BF3·OEt2 −78°C; (ii) ZnCl2, room temp. CH2Cl2, then Ac2O.
4. Experimental
excluded the alternative 32. Reaction of the xylofura-
nose derivative 3620 with aldehyde 11 catalyzed with
BF3·OEt2 proceeded analogously and afforded the cor-
responding disaccharide 37 (as a mixture of isomers),
the structure of which was also assigned by chemical
degradation (Scheme 4).
4.1. General
NMR spectra were recorded with a Bruker AM 500
spectrometer for solutions in CDCl3 (internal Me4Si)
unless otherwise stated. Most of the resonances were as
signed by COSY (1H–1H) and/or HETCOR and DEPT
correlations. The relative configurations of the protons
were determined by NOE or NOESY experiments.
Mass spectra were recorded with an AMD-604 (AMD
Intectra GmbH, Germany); (LSIMS (m-nitrobenzyl
alcohol was used as a matrix to which sodium acetate
was added)) mass spectrometer. Specific rotations were
measured with a JASCO DIP digital polarimeter for
chloroform solution (cꢀ1.5, unless otherwise stated) at
room temperature. Column chromatography was per-
formed on silica gel (Merck, 70–230 mesh). Organic
solutions were dried over anhydrous magnesium or
sodium sulfate.
3. Conclusion
The reaction of sugar allyltin derivatives of pyranoses
with aldehydes catalyzed by BF3·OEt2 is a convenient
and highly stereoselective method for the synthesis of
higher carbon sugars. The coupling process proceeds
according to the open-chain model, widely accepted for
such transformations.
The same reaction performed with the furanose-derived
allyltins was unsuccessful as decomposition of the fura-
nosyl ring by the Lewis acid catalyst was much faster
than the desired coupling process.
Allyltin derivatives: methyl 2,3,4-tri-O-benzyl-6,7,8-
trideoxy-8-tributylstannyl-oct-6-eno-a-D -gluco-1,5-

S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
1901
pyranoside7 6, methyl 2,3,4-tri-O-benzyl-6,7,8-trideoxy-
8-tributylstannyl-6-eno-a-
-manno-1,5-pyranoside7 10,
3-O-benzyl-1,2-O-isopropylidene-5,6,7-trideoxy-7-tribu-
tylstannyl-hept-5-ene-a-
-ribo-1,4-furanose7 27, and 3-
O-benzyl-1,2-O-iso-propylidene-5,6,7-trideoxy-7-trib-
utylstannyl-hept-5-ene-a-
-xylo-1,4-furanose 36,20 were
prepared according to literature methods. 2,3:4,5-Di-O-
isopropylidene-
-arabinose15 11 was obtained by a
periodate cleavage of 3,4:5,6-di-O-isopropylidene-
glucitol readily available22 from
-glucuronolactone.
bridge Crystallographic Data Centre as supplementary
publication no. CCDC-166869.
D
D
4.3. Reaction of allyltin pyranosides with aldehydes
D
Sugar allyltin derivative 6 or 10 (3 mmol) and aldehyde
11 or 20 (3.5 mmol) was dissolved in methylene chlo-
ride (100 mL) under an argon atmosphere and cooled
to −78°C. Boron trifluoride etherate (0.46 mL, 3.6
mmol) was added via syringe in one portion and the
mixture was stirred for ca. 30 min (TLC monitoring in
hexane:ethyl acetate, 4:1). Water (50 mL) was added,
the organic layer was separated and the aqueous phase
extracted with ethyl acetate (3×100 mL). The combined
organic phase was washed with water (30 mL), brine
(30 mL), dried, concentrated and the product(s) was
isolated by column chromatography: hexane:ethyl ace-
tate, 6:1.
D
D
-
D
4.2. Crystal data for compound 13
Crystal data for compound 13 are given in Table 1,
together with refinement details. All measurements of
crystal were performed on a Kuma KM4CCD s-axis
diffractometer with graphite-monochromated Mo Ka
radiation. The crystal was positioned at 65 mm from
the KM4CCD camera. A total of 612 frames were
measured at 0.75° intervals with a counting time of 30
s. The data were corrected for Lorentz and polarization
effects. No absorption correction was applied. Data
reduction and analysis were carried out with the Kuma
Diffraction (Wrocław) programs. The structure was
solved by direct methods (program SHELXS-9723 and
refined by the full-matrix least-squares method on all
F2 data using the SHELXL-9724 programs. Non-hydro-
gen atoms were refined with anisotropic thermal
parameters; hydrogen atoms were included from the Dz
maps and refined with isotropic thermal parameters.
“ Reaction of 6 with 11 gave 12 (81%) as the only
product.
“ Reaction of 10 with 11 gave 18 (80%) and two
side-products 18% (2%) and 18%% (3%).
“ Reaction of 10 with 20 gave 21 (26%) and 22 (49%).
4.3.1. Methyl 2,3,4-tri-O-benzyl-6-deoxy-8,9:10,11-di-O-
isopropylidene-6-vinyl-a-
D
-gluco-
D
-gulo-
D
-glycero-unde-
coside
12. HRMS (LSIMS)
m/z: 727.3453
[C41H52NaO10 (M+Na+) requires: 727.3458].
1
Acetate: [h]D +1.7; H NMR: l 5.92 (ddd, J1%,6 9.8, J1%,2%
17.1, J1%,2%a 9.9, H-1%), 5.32 (d, J6,7 9.0, H-7), 5.18 (dd,
J2%,2%a 1.0, H-2%), 5.12 (dd, H-2%a), 4.62 (d, J1,2 3.5, H-1),
4.28 (d, J8,9 6.6, H-8), 4.05 (m, H-10 and H-11), 3.90
(m, H-3 and H-11a), 3.73 (dd, J4,5 10.2, J5,6 2.1, H-5),
3.68 (dd, J9,10 6.8, H-9), 3.62 (dd, J3,4 8.7, H-4), 3.36
(H-2 and OCH3), 3.21 (m, H-6), 2.06 (CH3CO2), 1.42,
1.36, 1.34 and 1.32 [2×C(CH3)2]; 13C NMR: l 169.7
(CꢁO), 136.6 (C-1%), 118.0 (C-2%), 109.7 and 109.5 [2×
C(CH3)2], 97.5 (C-1), 82.3, 80.0, 79.8, 79.1, 77.2, 76.7,
72.5 and 71.2 (C-2,3,4,5,7,8,9,10), 75.6, 74.6 and 73.1
(3×CH2Ph), 66.8 (C-11), 55.2 (OCH3), 44.9 (C-6), 27.6,
26.8, 26.3 and 25.2 [2×C(CH3)2], 21.3 (CH3CO2).
Crystallographic data (excluding structure factors) for
the structure of 13 have been deposited with the Cam-
Table 1. Crystal data and structure refinement
Empirical formula
Formula weight
Temperature (K)
C44H56O10
744.89
100(2)
,
u (A)
0.71073
Monoclinic
P21
Crystal system
Space group
,
a (A)
11.773(2)
13.585(3)
13.888(3)
111.90(3)
2060.9(7)
2
1.200
0.084
800
,
b (A)
This compound was allylated under standard condi-
tions (AllBr, NaH in DMF) to afford methyl 7-O-allyl-
2,3,4-tri-O-benzyl-6-deoxy-8,9:10,11-di-O-isopropyli-
,
c (A)
i (°)
V (A
−3
,
)
Z
dene-6-vinyl-a-D-gluco-D-gulo-D-glycero-undecoside 15;
Dcalcd (Mg m−3
)
mp 104–105°C (heptane–ether). 13C NMR: l 137.4 and
134.6 (2×CHꢁCH2), 117.7 and 115.8 (2×CHꢁCH2),
109.5 and 108.6 [2×C(CH3)2], 97.9 (C-1), 82.6, 81.6,
80.0, 79.7, 77.2, 77.1, 77.6 and 72.7 (C-2,3,4,5,7,8,9,10),
75.4, 74.6, 73.2 and 72.7 (3×CH2Ph+CH2-CHꢁCH2),
68.1 (C-11), 45.3 (C-6), 27.1, 26.7, 26.4 and 25.2 [2×
C(CH3)2]
v (mm−1
F(000)
)
Crystal size (mm)
Diffractometer
q Range for data collection (°)
Index ranges (°)
0.20×0.20×0.15
Kuma KM4CCD
3.47–28.75
h: −15“15
k: −13“17
l: −17“18
14647
7016 (Rint=0.0150)
7016/711
1.030
For the X-ray assignment, see Fig. 4.
Reflections collected
Independent reflections
Data/parameters
4.3.2. Methyl 2,3,4-tri-O-benzyl-6-deoxy-8,9:10,11-di-O-
Goodness-of-fit (F2)
isopropylidene-6-vinyl-a-
D
-manno-
D
-gulo- -glycero-
D
Final R1/wR2 indices (I\2|I)
0.0285/0.0702
0.208/−0.196
−3
undecoside 18. HRMS (LSIMS) m/z: 727.3463
,
Largest diff. peak/hole (e A
)
[C41H52NaO10 (M+Na+) requires: 727.3458].

1902
S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
Acetate: [h]D −6.95 (c=0.6); 1H NMR: l 6.00 (ddd, J1%,6
9.8, J1%,2% 17.2, J1%,2%a 10.2, H-1%), 5.37 (d, J6,7 9.6, H-7),
5.20 (dd, J2%,2%a 1.2, H-2%), 5.13 (dd, H-2%a), 4.71 (d, J1,2
1.1, H-1), 4.34 (dd, J7,8 0.8, J8,9 5.2, H-8), 4.10 (dd, J3,4
9.0, J4,5 9.9, H-4), 4.02,(m, H-10 and H-11), 3.91 (m,
H-11a), 3.73 (m, H-2, H-3 and H-9), 3.63 (dd, J5,6 1.6,
H-5), 3.41 (m, H-6), 3.27 (OCH3), 1.96 (CH3CO2), 1.41,
1.36, 1.36 and 1.32 [2×C(CH3)2]; 13C NMR: l 170.3
(CꢁO), 137.5 (C-1%), 118.0 (C-2%), 109.7 and 109.4 [2×
C(CH3)2], 98.7 (C-1), 80.5, 78.9, 77.0, 76.9, 76.4, 75.8,
74.2 and 70.8 (C-2,3,4,5,7,8,9,10), 74.9, 73.0 and 72.1
(3×CH2Ph), 66.4 (C-11), 54.7 (OCH3), 43.6 (C-6), 27.6,
26.9, 26.4 and 25.3 [2×C(CH3)2], 21.3 (CH3CO2).
77.5, 76.8, 75.0, 71.9 and 71.5 (C-2,3,4,5,7,8,9,10), 74.3,
72.2 and 71.9 (3×CH2Ph), 66.9 (C-11), 55.5 (OCH3),
44.7 (C-6), 27.2 (double), 26.4 and 25.6 [2×C(CH3)2],
21.3 (CH3CO2).
4.3.5. Methyl 2,3,4-tri-O-benzyl-8-O-tert-butyldiphenyl-
silyl-6-deoxy-6-vinyl-a-
D
-manno- -erythro-octoside 21.
D
This compound was characterized as diacetate 23-Ac,
after removal of the TBDPS block with a HF·py com-
plex followed by reaction of resulting diol with Ac2O/
py. 23-Ac: HRMS (LSIMS) m/z: 641.2727
[C36H42NaO9 (M+Na+) requires: 641.2727]. [h]D +5.5;
1H NMR: l 5.87 (dt, J1%,6 9.9 J1%,2% 17.1, J1%.2%a 9.9, H-1%),
5.45 (ddd, J6,7 8.5, J7,8 2.3, J7,8% 6.5, H-7), 5.14 (m,
H-2%), 4.69 (d, J1,2 1.54, H-1), 4.44 (dd, J8,8a 12.2, H-8),
4.09 (t, J3,4 9.5, J4,5 9.5, H-4), 4.02 (dd, H-8a), 3.79 (dd,
J2,3 3.0, H-3), 3.73 (dd, H-2), 3.61 (dd, J5,6 1.6, H-5),
3.26 (OCH3), 3.02 (m, H-6), 1.97 and 1.90 (2×CH3CO2);
13C NMR: l 170.7 and 170.0 (2×CꢁO), 135.9 (C-1%),
118.2 (C-2%), 98.6 (C-1), 80.4, 76.5, 75.1, 73.5 and 70.4
(C-2,3,4,5,7), 74.7, 72.7 and 71.9 (3×CH2Ph), 64.6 (C-
8), 54.8 (OCH3), 43.8 (C-6), 21.1 and 20.7 (2×CH3CO2).
This compound was converted into its p-nitrobenzoate
derivative by action of p-nitrobenzoyl chloride in pyri-
dine; mp 84–85°C (heptane–ether). 13C NMR: l 163.4
(CꢁO), 137.0 (C-1%), 118.4 (C-2%), 109.7 and 109.2 [2×
C(CH3)2], 98.8 (C-1), 80.4, 79.3, 77.0, 76.7, 76.5, 75.8,
73.7 and 72.0 (C-2,3,4,5,7,8,9,10), 74.7, 72.6 and 71.7
(3×CH2Ph), 67.0 (C-11), 54.7 (OCH3), 45.1 (C-6), 27.1
(double), 26.5 and 25.3 [2×C(CH3)2].
No crystal suitable for X-ray analysis could be
obtained.
4.3.6. Methyl 2,3,4-tri-O-benzyl-8-O-tert-butyldiphenyl-
silyl-6-deoxy-6-vinyl-a-
D
-manno- -erythro-octoside 22.
L
Likewise this compound was characterized as diacetate
24-Ac. HRMS (ESI) m/z: 641.2733 [C36H42NaO9 (M+
4.3.3. Methyl 2,3,4-tri-O-benzyl-6-deoxy-8,9:10,11-di-O-
1
Na+) requires: 641.2721]. [h]D −10.7; H NMR: l 5.91
isopropylidene-6-vinyl-a-
D
-manno-
D
-galacto- -glycero-
D
undecoside 18%‡. HRMS (ESI) m/z: 727.3509
[C41H52NaO10 (M+Na+) requires: 727.3453].
(dt, J1%,6 10.2, J1%,2% 10.2, J1%.2%a 17.3, H-1%), 5.31 (dd, J2%,2%a
1.9, H-2%), 5.25 (ddd, J6,7 10.3, J7,8 2.4, J7,8a 5.2, H-7),
5.13 (dd, H-2%a), 4.66 (d, J1,2 2.3, H-1), 4.50 (dd, J8,8a
12.3, H-8), 3.96 (dd, H-8a), 3.88 (m, H-3 and H-4), 3.79
(dd, J5,6 1.4, H-5), 3.74 (t, J2,3 2.2, H-2), 3.22 (OCH3),
3.02 (H-6), 2.06 and 2.03 (2×CH3CO2); 13C NMR: l
170.6 and 170.5 (2×CꢁO), 133.0 (C-1%), 121.3 (C-2%),
98.9 (C-1), 80.3, 75.4, 74.5, 70.1 and 69.5 (C-2,3,4,5,7),
74.8, 72.3 and 71.8 (3×CH2Ph), 64.0 (C-8), 54.9
(OCH3), 45.1 (C-6), 21.1 and 20.7 (2×CH3CO2).
1
Acetate: H NMR: l 6.01 (dt, J1%,6 10.2, J1%,2% 17.3, J1%,2%a
10.2, H-1%), 5.37 (dd, J6,7 10.2, J7,8 1.6, H-7), 5.19 (dd,
J1%,2%a 2.2, H-2%), 5.06 (dd, H-2%a), 4.75 (d, J1,2 1.9, H-1),
4.40 (dd, J8,9 6.4, H-8), 4.11 (dd, J10,11 6.2, J11,11a 8.5,
H-11), 3.98 (ddd, J10,11a 5.7, H-10), 3.90 (m, H-3, H-4,
H-5, H-11a), 3.86 (dd, J2,3 2.0, H-2), 3.69 (dd, J9,10 8.5,
H-9), 3.38 (OCH3), 3.15 (t, H-6), 2.02 (CH3CO2), 1.46,
1.41, 1.36 and 1.24 [2×C(CH3)2]; 13C NMR: l 169.9
(CꢁO), 135.1 (C-1%), 119.8 (C-2%), 110.3 and 109.6 [2×
C(CH3)2], 98.9 (C-1), 80.0, 78.8, 78.0, 77.5, 75.8, 74.4,
71.1 and 70.7 (C-2,3,4,5,7,8,9,10), 74.4, 72.2 and 71.9
(3×CH2Ph), 67.8 (C-11), 55.3 (OCH3), 46.9 (C-6), 28.0,
26.9, 26.5 and 25.3 [2×C(CH3)2], 21.2 (CH3CO2).
For the CD assignment of the configuration at the C(7)
center of the diol 24, see Fig. 6.
4.4. Assignment of the configurations of 18, 21 and 22
4.4.1. Degradation of 18: methyl 2,3,4-tri-O-benzyl-6-
deoxy-6-vinyl-a-
D
-manno- -erythro-octoside 19. To a
D
4.3.4. Methyl 2,3,4-tri-O-benzyl-6-deoxy-8,9:10,11-di-O-
solution alcohol 18 (520 mg, 0.8 mmol) in DMF (25
mL) sodium hydride (60% dispersion in mineral oil, 100
mg) was added and the mixture was stirred for 30 min
at rt under an argon atmosphere. Allyl bromide (0.15
mL, 1.7 mmol) was added, the mixture was stirred for
another 2 h at rt, excess of hydride was decomposed by
careful addition of water (2 mL) and the mixture was
partitioned between water:ether. The organic phase was
separated, dried, concentrated and the product was
purified by column chromatography (hexane:ethyl ace-
tate, 6:1).
isopropylidene-6-vinyl-a-
D
-manno-D-talo-D-glycero-
undecoside 18%%. HRMS (LSIMS) m/z: 727.3443
[C41H52NaO10 (M+Na+) requires: 727.3458].
1
Acetate: H NMR: l 5.94 (dt, J1%,6 10.2, J1%,2% 17.4, J1%,2%a
10.2, H-1%), 5.49 (dd, J6,7 9.3, J7,8 3.5, H-7), 5.31 (dd,
J2%,2%a 2.0, H-2%), 5.06 (dd, H-2%a), 4.64 (d, J1,2 2.0, H-1),
4.15 (dd, J8,9 6.3, H-8), 4.05 and 3.89 (2×m, H-
3,4,5,9,10,11,11a), 3.73 (dd, J2,3 2.1, H-2), 3.30 (OCH3),
3.10 (m, H-6), 2.10 (CH3CO2), 1.35, 1.33, 1.28 and 1.27
[2×C(CH3)2]; 13C NMR: l 134.2 (C-1%), 120.5 (C-2%),
109.6 and 109.0 [2×C(CH3)2], 99.1 (C-1), 80.7, 80.2,
The product was dissolved in THF/water (2:1, v/v, 25
mL) to which conc. H2SO4 (0.5 mL) was added, the
mixture was heated under reflux for 16 h, cooled to rt
and neutralized by addition of solid sodium bicarbon-
ate. Sodium periodate (0.8 g) was added, the mixture
‡ The assignment of the configuration in 18% and 18%% is tentative; for
the more abundant isomer 18%% we proposed the alternative (to 18)
erythro structure, while for 18% the threo one with the same configu-
ration at the C(6) as in major isomer 18.

S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
1903
was stirred for 1 h at room temperature and partitioned
between brine (20 mL) and ethyl acetate (50 mL). The
organic layer was separated, washed with water, and
concentrated. The residue was dissolved in THF/
methanol (1:1, v/v, 20 mL), the crude aldehyde was
reduced with sodium borohydride (400 mg) for 3 h, and
the product 19 was isolated by column chromatography
(hexane:ethyl acetate, 2:1“1:1). The CD spectrum of
the diol 19 is shown in Fig. 6. Acetylation of 19
afforded diacetate, the NMR spectrum of which was
identical with 23-Ac.
135.5, 129.5 (C-9, C-10 and C-11), 118.5 (C-12),
110.5, 109.8 [2×C(CH3)2], 104.5 (C-6), 97.1 (C-
5), 86.8, 80.9, 78.6, 77.2, 77.0 (C-8, C-7, C-4,
C-3, C-2), 70.5 (C-1), 67.6 (CH2Ph), 27.3, 26.7,
26.2, 25.2 [2×C(CH3)2].
Mixture of 33-III and 33-IV in a 4:1 ratio
HRMS (LSIMS) m/z: 485.2145 [C25H34O8Na
(M+Na+) requires: 485.2151].
Main isomer: 1H NMR: l 6.48–6.2 (m, J9,10
14.5, J11,12 10.5, H-10 and H-11), 5.7–5.55 (dd,
J9,10 14.5, J8,9 7.3, H-9), 2×1.39, 1.36, 1.32 [2×
C(CH3)2]; 13C NMR: l 135.8 135.4, 129.6 (C-9,
C-10 and C-11), 118.5 (C-12), 110.8, 109.5 [2×
C(CH3)2], 102.6 (C-6), 97.2 (C-5), 85.1, 78.6,
78.3, 77.2, 76.1 (C-8, C-7, C-4, C-3, C-2), 70.4
(C-1), 65.6 (CH2Ph), 27.4, 26.9, 26.4, 25.2 [2×
C(CH3)2].
4.4.2. Methyl 2,3,4-tri-O-benzyl-6-deoxy-6-vinyl-a-
D-
manno- -glycero-heptoside 25. Diol 23 (obtained from
D
21, 200 mg, 0.37 mmol) was dissolved in ether (25 mL)
to which sodium periodate (0.5 g) in water (10 mL) was
added and the heterogeneous mixture was stirred for 30
min at room temperature. The organic layer was sepa-
rated, washed with water, concentrated and the crude
aldehyde was reduced with NaBH4 (250 mg) under
standard conditions to afford the title compound 25
which was characterized as acetate 25-Ac: HRMS (ESI)
m/z: 569.2552 [C33H38NaO7 (M+Na+) requires:
Minor isomer: 13C NMR: l 136.0 134.7, 130.6
(C-9, C-10 and C-11), 118.3 (C-12), 110.7, 109.6
[2×C(CH3)2], 102.8 (C-6), 94.5 (C-5), 82.5, 79.4,
77.3, 77.2, 76.8 (C-8, C-7, C-4, C-3, C-2), 71.0
(C-1), 67.5 (CH2Ph), 2×27.2, 2×26.6 [2×
C(CH3)2].
1
569.2510]. [h]D 13.0; H NMR (200 MHz): l 5.91 (ddd,
“ Reaction of 36 with 11 gave 37 [92%; four isomers in
J1%,6 8.5, J1%,2% 10.2, J1%,2%a 17.3, H-1%), 5.16 and 5.09 (2×m,
both H-2%), 4.69 (d, J1,2 2.4, H-1), 4.34 (dd, J6,7 5.5, J7,7a
11.1, H-7), 4.24 (dd, J6,7a 7.7, H-7a), 3.92 (t, J3,4=J4,5
9.0, H-4), 3.85 (m, H-5), 3.75 (dd, H-2), 3.65 (dd, J2,3
3.3, H-3), 3.26 (OCH3), 2.87 (m, H-6), 2.00 (CH3CO2);
13C NMR: l 170.9 (CꢁO), 137.3 (C-1%), 116.5 (C-2%),
98.8 (C-1), 80.5, 76.0, 74.8 and 72.7 (C-2,3,4,5), 74.4,
72.5 and 72.1 (3×CH2Ph), 63.8 (C-7), 54.7 (OCH3), 43.7
(C-6), 21.1 (CH3CO2).
the ratio
1
(single isomer):5 (three other
compounds)]
Compound 37-I
HRMS (ESI) m/z: 485.2134 [C25H34O8Na (M+
Na+) requires: 485.2151]
1
[h]D +36.9; H NMR: l 6.48–6.17 (m, J9,10 14.5,
J11,12 10.6, H-10 and H-11), 5.70–5.56 (dd, J9,10
14.5, J8,9 8.5, H-9), 1.43, 2×1.40, 1.32 [2×
C(CH3)2]; 13C NMR: l 135.9 135.8, 128.9 (C-9,
C-10 and C-11), 118.5 (C-12), 110.5, 109.7 [2×
C(CH3)2], 104.7 (C-6), 96.6 (C-5), 86.7, 80.7,
78.2, 77.1, 76.8 (C-8, C-7, C-4, C-3, C-2), 70.1
(C-1), 67.4 (CH2Ph), 27.1, 26.6, 26.1, 25.1 [2×
C(CH3)2].
4.4.3. Methyl 2,3,4-tri-O-benzyl-6-deoxy-6-vinyl-a-
D-
manno- -glycero-heptoside 26. Diol 24 (obtained from
L
22, 200 mg) was converted in the same manner into 26
(170 mg), which was characterized as acetate 26-Ac:
HRMS (ESI) m/z: 569.2546 [C33H38NaO7 (M+Na+)
Mixture 37-II, 37-III, and 37-IV in a 8:2:1 ratio
HRMS (ESI) m/z: 485.2140 [C25H34O8Na (M+
Na+) requires: 485.2151].
1
requires: 569.2510]. H NMR (200 MHz): l 5.94 (ddd,
J1%,6 9.3, J1%,2% 10.4, J1%,2%a 17.2, H-1%), 5.27 and 5.19 (2×m,
both H-2%), 4.20 (dd, J6,7 7.33, J7,7a 10.7, H-7), 4.13 (dd,
J6,7a 8.4, H-7a), 3.92–3.74 (m, H-2,3,4,5), 3.27 (OCH3),
3.00 (m, H-6), 2.03 (CH3CO2); 13C NMR: l 170.8
(CꢁO), 134.0 (C-1%), 119.9 (C-2%), 98.7 (C-1), 80.5, 75.5,
74.5 and 69.8 (C-2,3,4,5), 74.9, 72.4 and 71.9 (3×
CH2Ph), 64.5 (C-7), 54.5 (OCH3), 43.3 (C-6), 20.0
(CH3CO2).
1
Main isomer: H NMR: l 6.48–6.18 (m, J9,10
14.6, J11,12 10.5, H-10 and H-11), 5.75–5.57 (m,
J9,10 14.5, J8,9 7.5, H-9), 2×1.41, 2×1.40 [2×
C(CH3)2]; 13C NMR: l 135.8, 135.5, 129.0 (C-9,
C-10 and C-11), 118.6 (C-12), 110.7, 109.4 [2×
C(CH3)2], 102.8 (C-6), 96.6 (C-5), 85.0, 78.4,
78.1, 77.1, 76.0 (C-8, C-7, C-4, C-3, C-2), 70.4
(C-1), 65.5 (CH2Ph), 27.4, 27.0, 26.4, 25.3 [2×
C(CH3)2].
4.5. Reaction of allyltin furanosides with aldehyde 11
This reaction was performed in the same manner as for
6 and 10, except that the products were purified using
hexane:ethyl acetate, 4:1.
4.6. Degradation of the products from reactions of
furanose-allyltins with aldehyde 11
“ Reaction of 27 with 11 gave 33 (72%; two pairs of
isomers in the ratio 1:4)
The appropriate disaccharide (ca. 1.5 mmol; from con-
densation of either 27 or 36 with 11) was dissolved in
THF (10 mL) and water (4 mL) to which conc. sulfuric
acid (25 drops) was added. The mixture was stirred for
12 h at room temperature and neutralized by addition
of triethylamine (0.8 mL). More water (2 mL) was
added followed by NaBH4 (ca. 50 mg), the mixture was
stirred at room temperature for a further 3 h, and
concentrated. The residue was dried by co-evaporation
Mixture of 33-I and 33-II in a 7:1 ratio
HRMS (LSIMS) m/z: 485.2135 [C25H34O8Na
(M+Na+) requires: 485.2151].
1
Main isomer: H NMR: l 6.48–6.17 (m, J9,10
14.4, J11,12 10.6, J11,12a 16.8, H-10 and H-11),
5.68–5.50 (dd, J9,10 14.4, J8,9 7.7, H-9), 1.44,
1.41, 1.39, 1.32 [2×C(CH3)2]; 13C NMR: l 135.9

1904
S. Jarosz et al. / Tetrahedron: Asymmetry 12 (2001) 1895–1905
with toluene (3×15 mL). The boronic species were
removed by co-evaporation with methanol (3×15 mL)
and the residue was finally dried by co-evaporation
with toluene (10 mL). Pyridine (10 mL) was added
followed by Ac2O (5 mL) and DMAP (ꢀ50 mg). The
mixture was stirred at room temperature for 2 h and
concentrated. Ether (100 mL) was added to the residue,
the organic layer was washed with water, brine, dried
and concentrated and the pentitol derivative (identified
with the standard prepared independently see Section
4.6) was isolated by column chromatography (hex-
ane:ethyl acetate, 4:1“2:1)
References
1. Gyorgydeak, Z.; Pelyvas, I. In Monosaccharide sugars:
chemical synthesis by chain elongation, degradation and
epimerization; Academic Press, 1998, this book covers
the literature up to 1997. For more recent papers see
for example: Marquis, Ch.; Picasso, S.; Vogel, P. Syn-
thesis 1999, 1441–1452; Blackwell, H. E.; O’Leary, D.
J.; Chatterjee, A. K.; Washenfelder, R. C.; Bussmann,
D. A.; Grubbs, R. H. J. Am. Chem. Soc. 2000, 122,
58–71; Maria, E. J.; da Silva, A. D.; Fourrey, J.-L. Eur.
J. Org. Chem. 2000, 627–631 and references cited
therein.
2. Jarosz, S. J. Carbohydr. Chem. 2001, 20, 93–107.
3. (a) Jarosz, S.; Mootoo, D. R.; Fraser-Reid, B. Carbo-
hydr. Res. 1986, 147, 59–68; (b) Jarosz, S. Carbohydr.
Res. 1988, 183, 201–207; (c) Jarosz, S. Carbohydr. Res.
1992, 224, 73–81; (d) Jarosz, S.; Salanski, P.; Mach, M.
Tetrahedron 1998, 54, 2583–2594.
In the 13C NMR spectra of the products obtained from
degradation of all stereoisomers derived from conden-
sation of furanosidic allyltins with aldehyde 11 only
signals characteristic for penta-O-acetyl-D-arabinitol
were seen while no signals of the penta-O-acetyl-xylitol
were visible.
4. Jarosz, S.; Mach, M. J. Chem. Soc., Perkin Trans. 1
1998, 3943–3948 and references cited therein.
5. (a) Jarosz, S. Carbohydr. Res. 1987, 167, 211; (b)
Jarosz, S. Tetrahedron Lett. 1988, 29, 1193–1196; (c)
Jarosz, S. J. Carbohydr. Chem. 1993, 12, 1149–1160.
6. Jarosz, S.; Fraser-Reid, B. J. Org. Chem. 1989, 54,
4011–4013.
7. Kozlowska, E.; Jarosz, S. J. Carbohydr. Chem. 1994,
13, 889–898.
8. Mach, M.; Jarosz, S. Polish J. Chem. 1997, 71, 936–
940.
9. (a) Jarosz, S.; Kozlowska, E.; Jezewski, A. Tetrahedron
1997, 53, 10775–10782; (b) Jarosz, S.; Sko´ra, S. Tetra-
hedron: Asymmetry 2000, 11, 1425–1432.
10. (a) Jarosz, S. J. Chem. Soc., Perkin Trans. 1 1997,
3579–3580; (b) Jarosz, S.; Sko´ra, S. Tetrahedron: Asym-
metry 2000, 11, 1433–1448.
11. Servens, C.; Pereyre, M. J. Organomet. Chem. 1972, 35,
C20–C22.
12. Yamamoto, Y.; Maruyama, K.; Matsumoto, K. J.
Chem. Soc., Chem Commun. 1983, 489–490.
4.7. Synthesis of models
4.7.1. Penta-O-acetyl-xylitol21 34.
D-Xylose (0.5 g, 3.3
mmol) was dissolved in water (5 mL), reduced with
NaBH4 (60 mg) at rt for 1 h, concentrated and the
residue was dried by co-evaporation with toluene (3×10
mL). Boron species were removed by co-evaporation
with methanol (3×10 mL) and the residue was finally
dried by co-evaporation with toluene (2×10 mL). Pyri-
dine (10 mL) was added followed by Ac2O (5 mL) and
DMAP (ꢀ20 mg). The mixture was stirred at room
temperature for 2 h and concentrated. Ether (50 mL)
was added to the residue, the organic layer was washed
with water, brine, dried and concentrated and the
desired penta-O-acetyl xylitol was isolated by column
chromatography (hexane:ethyl acetate, 4:1“2:1); yield
1
470 mg. H NMR: l 5.39 (d, J 5.3, H-3), 5.29 (ddd, J
4.3, 5.3 and 6.0, H-2 and H-4), 4.35 (dd, J 4.3 and
12.05, H-1 and H-5), 3.99 (dd, J 6.0 and 12.05, H-1a
and H-5a), 2.11 (CH3CO2), 2.10 (2×CH3CO2), 2.06
(2×CH3CO2); 13C NMR: l 170.2 (2×CꢁO), 169.8 (2×
CꢁO), 169.5 (CꢁO), 2×69.0 (C-2, C-4), 68.9 (C-3), 62.4
(C-1, C-5), 20.7 (double), 20.6 (double) and 20.5 (5×
CH3CO2).
13. Keck, G. E.; Enholm, E. J.; Kachensky, D. F. Tetra-
hedron Lett. 1984, 25, 1867–1870.
14. (a) Yamamoto, Y.; Yatagi, H.; Ishihara, Y.; Maeda,
N.; Maruyama, K. Tetrahedron 1984, 40, 2239–2246; (b)
Yamamoto, Y. Acc. Chem. Res. 1987, 20, 243–249; (c)
Yamamoto, Y.; Asao, N. Chem. Rev. 1993, 93, 2207–
2293; (d) Sumida, S.; Ohga, M.; Mitani, J.; Nokami, J.
J. Am. Chem. Soc. 2000, 122, 1310–1313 and references
cited therein.
15. Regeglink, H.; de Rouville, E.; Chittenden, G. J. F.
Recl. Trav. Chim. Pays-Bas 1987, 106, 461–464.
16. Jarosz, S.; Sko´ra, S.; Kosciolowska, I. Polish J. Chem.
1999, 73, 1797–1802.
17. (a) Frelek, J.; Pakulski, Z.; Zamojski, A. Tetrahedron:
Asymmetry 1996, 7, 1363–1372; (b) Frelek, J.; Geiger,
M.; Voelter, W. Curr. Org. Chem. 1993, 3, 145–174 and
references cited therein; (c) Jarosz, S.; Mach, M.;
Frelek, J. J. Carbohydr. Chem. 2000, 19, 693–715; (d)
Jarosz, S.; Sko´ra, S.; Stefanowicz, A.; Mach, M.;
Frelek, J. J. Carbohydr. Chem. 1999, 18, 961–974.
4.7.2. Penta-O-acetyl-
isopropylidene-
-arabinose15 (11; 0.55 g, 2.4 mmol) was
D
-arabinitol21 35. 2,3:4,5-Di-O-
D
dissolved in methanol (5 mL) and reduced with NaBH4
(150 mg) for 2 h. The product—isolated in usual way—
was dissolved in methanol (10 mL) to which conc.
H2SO4 (0.5 mL) was added and the mixture was stirred
at rt for 48 h. The mixture was neutralized with Et3N,
concentrated, the residue was dried and acetylated (as
for 34) to give penta-O-acetyl-D
-arabinitol (408 mg): 1H
NMR: l 5.45–5.10 (m, H-2, H-3 and H-4), 4.34–3.86
(m, both H-1 and both H-5), 2.13, 2.08, 2.062, 2.06,
2.04 (5×CH3CO2); 13C NMR: l 170.1, 170.0, 169.7,
169.3, 169.2 (5×CꢁO), 68.0, 67.8 (double) (C-2, C-3 and
C-4), 61.7, 61.4 (C-1 and C-5), 20.5, 3×20.4, 20.3 (5×
CH3CO2).

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