Synthesis of anomerically pure vinyl sulfone-modified pent-2-enofuranosides and hex-2-enopyranosides: A group of highly reactive Michael acceptors for accessing carbohydrate based synthons

Article abstract of DOI:10.1016/S0040-4020(03)01059-7

Syntheses of the benzyl or the trityl protected α- and β-anomers of vinyl sulfone-modified pent-2-enofuranosides have been initiated by the ring opening of the suitably masked methyl α-lyxofuranosyl-epoxide or methyl β-ribofuranosyl-epoxide or by the nucleophilic displacement of the leaving groups in benzyl protected 3-O-tosyl xylofuranoside and 3-O-mesyl ribofuranoside by p-thiocresol. In case of the latter set of starting materials, α- and β-methyl glycosides formed in almost equal ratio only from the derivatives of D-xylose. For the synthesis of α- and β-anomers of vinyl sulfone-modified hex-2-enopyranosides, a D-glucose derivative was selected over a D-allose derivative as the starting material because the former almost exclusively produced the required methyl pyranosides whereas the latter produced a mixture. All sulfides were converted to vinyl sulfone-modified carbohydrates by the sequential application of oxidation, mesylation and base induced elimination reactions.

Full text of DOI:10.1016/S0040-4020(03)01059-7

Tetrahedron 59 (2003) 7203–7214
Synthesis of anomerically pure vinyl sulfone-modified
pent-2-enofuranosides and hex-2-enopyranosides: a group of
highly reactive Michael acceptors for accessing carbohydrate
based synthons
Aditya Kumar Sankia and Tanmaya Pathakb
,
*
aOrganic Chemistry Division (Synthesis), National Chemical Laboratory, Pune 411 008, India
bDepartment of Chemistry, Indian Institute of Technology, Kharagpur 721 302, India
Received 28 March 2003; revised 10 June 2003; accepted 3 July 2003
Abstract—Syntheses of the benzyl or the trityl protected a- and b-anomers of vinyl sulfone-modified pent-2-enofuranosides have been
initiated by the ring opening of the suitably masked methyl a-lyxofuranosyl-epoxide or methyl b-ribofuranosyl-epoxide or by the
nucleophilic displacement of the leaving groups in benzyl protected 3-O-tosyl xylofuranoside and 3-O-mesyl ribofuranoside by p-thiocresol.
In case of the latter set of starting materials, a- and b-methyl glycosides formed in almost equal ratio only from the derivatives of D-xylose.
For the synthesis of a- and b-anomers of vinyl sulfone-modified hex-2-enopyranosides, a D-glucose derivative was selected over a D-allose
derivative as the starting material because the former almost exclusively produced the required methyl pyranosides whereas the latter
produced a mixture. All sulfides were converted to vinyl sulfone-modified carbohydrates by the sequential application of oxidation,
mesylation and base induced elimination reactions.
q 2003 Elsevier Ltd. All rights reserved.
1. Introduction
sulfonyl-a-D-erythro-hex-2-enopyranoside 1a and methyl
2,3-dideoxy-4,6-O-(phenylmethylene)-3-C-phenylsulfonyl-
The most common methods for the modification of
monosaccharides involve reactions of various reagents
with sugar derived epoxides, tosylates and ketones although
several other minor methods are also reported.1 Nucleo-
philic addition (Michael) to double bonds activated by
electron withdrawing groups as part of carbohydrates could
serve as a useful methodology for the functionalization of
monosaccharides. Several examples of Michael addition of
nucleophiles to hex-2-enose2 and 3-nitro-hex-2-enopyrano-
sides3 have been reported.
During the course of our studies on the synthesis of
carbohydrate modified monovinylsulfone4 and bisvinylsul-
fone substituted nucleosides,5 we envisaged that due to the
high reactivities of vinyl sulfones towards a wide variety of
nucleophiles, vinyl sulfone-modified carbohydrates could
be utilized to generate numerous modified monosacchar-
ides. Vinyl sulfone-modified carbohydrates are expected to
offer several additional advantages for synthetic chemistry,
which have been discussed in detail.6 The reported anomers,3i
methyl 2,3-dideoxy-4,6-O-(phenylmethylene)-3-C-phenyl-
Keywords: vinyl sulfone; pent-2-enopyranosides; hex-2-enopyranosides;
Michael acceptors.
*
Corresponding author. Tel.: þ91-3222283342; fax: þ91-3222282252;
e-mail: tpathak@chem.iitkgp.ernet.in
Figure 1.
0040–4020/$ - see front matter q 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0040-4020(03)01059-7

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A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
b-D-erythro-hex-2-enopyranoside 1b (Fig. 1) have been
synthesized and subjected to reactions with various amine-
s.6a–d The study has later been utilized for the synthesis of
D-lividosamine (a component of aminoglycoside antibiotics)
and its analogues.6b On the other hand, a facile route for the
synthesis of new branched chain sugars has been designed
recently by utilizing the directing effects of the anomeric
configuration of vinyl sulfone-modified pent-2-enofurano-
sides and hex-2-enopyranosides.6e
In order to broaden the scope of this study and also to gather
information on the reaction patterns of endocyclic mono-
vinylsulfones derived from pentofuranoses, we needed to
develop a practical methodology for the synthesis of
anomerically pure methyl 2,3-dideoxy-3-C-(p)-tolylsul-
fonyl-a-D-erythro-pent-2-enofuranoside (2a or 3a) and
methyl 2,3-dideoxy-3-C-(p)-tolylsulfonyl-b-D-erythro-
pent-2-enofuranoside (2b or 3b) (Fig. 1). Anomerically
pure, vinyl sulfone-modified pent-2-enofuranoses were
needed because we wanted to use the anomeric configur-
ation as a tool to direct the diastereoselectivity of addition of
nucleophiles to the 2-position of these enofuranoses.
However, this particular requirement imposed greater
restrictions on the choice of methodologies for the synthesis
of compounds 1, 2 and 3 starting from a single and easily
accessible starting materials.
Scheme 1. Reagents and conditions: (a) p-Thiocresol, NaOMe, DMF,
80–908C, 2.5–3 h; (b) MMPP, MeOH, room temperature, 2–3 h; (c) MsCl,
Py., 08C, 12–24 h.
afford sulfide derivatives 13 and 14, respectively with xylo-
configuration in high yields. Compounds 13 and 14 were
converted to the corresponding vinyl sulfones 2b and 3b via
sulfone derivatives 15 and 16 in the usual manner as
described above (Scheme 2).
It should be noted that this route allows the synthesis of
vinyl sulfone-modified pentofuranoses having the C-5
hydroxyl function masked with an acid labile trityl
protecting group because the trityl group is introduced
after the acid catalyzed methyl glycoside formation.
However, separate synthesis of epoxides 5/6 and 11/12
increases the number of steps and therefore, it was necessary
to devise different approaches towards the synthesis of vinyl
sulfone-modified carbohydrates.
2. Results and discussion
A retrosynthetic analysis of the route to 1, 2 and 3
necessitated the introduction of a tolylthio group at the
C-3 position of a hexose or a pentose sugar, respectively.
One of the easiest ways of forming a C-S bond would be the
regioselective opening of epoxides derived from carbo-
hydrates.1c It is also possible to introduce the p-tolylthio
group at the C-3 position of a hexose or a pentose sugar by
displacing the leaving group at the C-3 position of the easily
accessible starting materials 17, 26, 32 or 38. Synthesis of 1
or 2 and 3 via the addition of arylsulfenyl chloride to
suitably protected methyl 2,3-dideoxy-D-hex-2-enopyrano-
sides 4pyr or methyl 2,3-dideoxy-D-pent-2-enofuranoside
4fur (Fig. 1) as a method was ruled out because such an
addition to the corresponding olefinic nucleoside derivatives
was reported to produce a mixture of at least three
diastereomers.7
2.2. Synthesis of 2a and 2b from 3-O-tosylated D-
xylofuranose
Compound 1712 was reacted with p-thiocresol in the
presence of NaOMe in DMF at 1208C to produce sulfide
derivative 18 with ribo-configuration in 59% yield.
Compound 18 was deprotected and glycosylated in one
step in the presence of conc. H2SO4 in MeOH to generate a
mixture of two anomers 19 and 20 (1:10) in 78% yield. The
anomers 19 and 20 were separated at this stage by
chromatography and oxidized separately with MMPP in
MeOH to the corresponding sulfones 21 and 22,
respectively in excellent yields. The sulfones 21 and 22
2.1. Synthesis of 2 and 3 from epoxides derived from
carbohydrates
The known lyxo-epoxides 58 and 6,9 synthesized from
D-xylose, were treated separately with the sodium salt of
p-thiocresol in DMF at 80–908C to furnish sulfide
derivatives 7 and 8, respectively in good to excellent yields.
Compounds 7 and 8, when oxidized separately with MMPP
(magnesium monoperoxyphthalate) in MeOH generated the
corresponding sulfone derivatives 9 and 10, respectively in
high yields. Compounds 9 and 10, on treatment with mesyl
chloride in pyridine separately, afforded smoothly the
desired vinyl sulfone-modified carbohydrates 2a and 3a,
respectively in 82 and 84% yields (Scheme 1). Similarly, the
known ribo-epoxides 1110 and 1211 were treated separately
with the sodium salt of p-thiocresol in DMF at 80–908C to
Scheme 2. Reagents and conditions: (a) p-Thiocresol, NaOMe, DMF,
80–908C, 2.5–3.0 h; (b) MMPP, MeOH, room temperature, 2.5–3.0 h;
(c) MsCl. Py., 08C, 12 h.

A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7205
Scheme 3. Reagents and conditions: (a) p-Thiocresol, NaOMe, DMF, 115–
1208C, 3.5–4.0 h, 59%; (b) MeOH, conc. H2SO4, 65–708C, 3 h, 78%,
(19:20¼1:10); (c) MMPP, MeOH, room temperature, 3 h (21¼94% and
22¼93%); (d) MsCl, Py., 08C–room temperature, 18–24 h.
on treatment with mesyl chloride in pyridine afforded
smoothly the desired vinyl sulfone-modified carbohydrates
2a and 2b, respectively in high yields (Scheme 3).
The moderate yield of the ribo-product 18 can be partly
explained on the basis of the repulsion caused by the 1,2-O-
isopropylidene group to the incoming nucleophile.13
Although at this stage the less efficient conversion of 17
to 18 was acceptable, the major drawback of this
methodology was the unacceptable ratio of 19 and 20
(1:10) in the mixture. The lower ratio of a-anomer 19 in the
mixture of 19 and 20 contributed to the poor overall yield of
the vinyl sulfone derivative 2a.
Scheme 4. Reagents and conditions: (a) (i) (COCl)2,DMSO, CH2Cl2, Et3N,
2608C, 1.5 h; (ii) LAH, THF, 08C–room temperature, 3.5–4 h; (b) MsCl,
Py., 08C, 24 h; (c) NaSTol (p), DMF, 1458C, 3 h; (d) MeOH, conc. H2SO4,
65–708C, 3 h, 89% (28:13¼1.5:1); (e) MMPP, MeOH, room temperature,
3 h; (f) MsCl, Py., 08C–room temperature, 24 h.
anomers 28 and 13 in a ratio 1.5:1. Although this ratio was
acceptable for the synthesis of both the anomers 2a and 2b,
the overall yield again dropped due to the addition of two
synthetic steps for converting xylo-derivative 23 to ribo-
derivative 25 via a two-step oxidation-reduction process.
We therefore, looked for yet another route for the synthesis
of 2a and 2b.
2.3. Synthesis of 2a and 2b from 3-O-mesylated D-
ribofuranose
An examination of the percentage compositions of methyl
furanosides of D-ribose, D-arabinose, D-xylose and D-lyxose
revealed that the ratios of a- and b-furanosides present in
equilibrium were 1:3.4, 3.1:1, 1:1.5 and only a-isomer,
respectively.14 Thus, the pattern of glycosylation of various
pentose sugars dictated us to select a D-xylo-derivative
based strategy for the synthesis of an anomeric mixture
close to the ideal ratio of 1:1.
2.4. Synthesis of 2a and 2b from 3-O-tosylated methyl
D-xylofuranosides
It was possible to circumvent all the shortcomings
mentioned above by first converting the xylo-tosylate
derivative 17 to an anomeric mixture of 30 and 31.
Compound 17 was therefore treated with conc. H2SO4 in
MeOH to produce an anomeric mixture of 30 and 31 in a
ratio of 1:1.3 (a:b) in 89% yield. In the absence of any steric
hindrance exhibited by 17, the nucleophilic displacement of
the tosyl group of the mixture of 30 and 31 by p-thiocresol
proceeded smoothly at elevated temperature to afford a
mixture of 3-deoxy-3-C-(p)-tolylsulfide-D-ribofuranosides
19 and 20 in 94% yield. Compounds 19 and 20 were
separated and converted to the desired vinyl sulfone-
modified carbohydrates 2a and 2b, respectively in the
usual manner described above (Scheme 5).
5-O-Benzyl-1,2-O-isopropylidene-3-O-mesyl-a-D-ribo-
furanose 26, which had been synthesized from a known
compound 2315 (via oxidation-reduction followed by
mesylation), was subjected to nucleophilic displacement
by p-thiocresol in the presence of NaOMe in DMF to
generate a sulfide derivative 27 with xylo-configuration in
79% yield.
Compound 27 was deprotected and glycosylated in the
presence of conc. H2SO4 in MeOH in one step to afford a
mixture of both a- and b-anomers 28 and 13 (1.5:1) in
excellent yields. Compounds 28 and 13 were separated at
this stage by flash chromatography. On treatment with
MMPP in MeOH, compounds 28 and 13 produced the
corresponding sulfones 29 and 15, respectively in excellent
yields. Compound 15 on treatment with mesyl chloride in
pyridine smoothly generated the desired vinyl sulfone 2b in
87% yield whereas 29 generated the desired vinyl sulfone
2a in good yield (Scheme 4).
2.5. Synthesis of 1a and 1b from 3-O-tosylated D-
glucofuranose
For accessing relatively large amount of anomerically pure
1a and 1b through a shorter route, we applied the
glycosylation driven strategy, which was successfully
utilized in the synthesis of 2a and 2b, for the selection of
starting sugar for the synthesis of 1a and 1b. It has been
reported that the equilibrium mixture of methyl-D-allosides
Compound 27 on methanolysis produced a mixture of

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Scheme 7. Reagents and conditions: (a) PhSH, NaOMe, DMF, 135–1408C,
2 h, 39%.
Scheme 5. Reagents and conditions: (a) MeOH, conc. H2SO4, 65–708C,
3 h, 89% (30:31¼1:1.3); (b) p-Thiocresol, NaOMe, DMF, 115–1208C,
3.5–4.0 h, 94%.
this reaction sequence because it was not possible to
synthesize the desired vinyl sulfone 1a from 37.
in MeOH, contained more than 30% of furanosides16
whereas D-glucose produced14 methyl-D-pyranosides
almost exclusively. Although the reported ratio of a- and
b-anomers were not close to the ideal value of 1:1, in this
case it was more important to get the methyl pyranosides
without any contamination of the corresponding furano-
sides. This observation prompted us to study the feasibility
of using the known tosylate 32 as the starting material.17
2.6. Synthesis of 1a and 1b from 3-O-mesylated
D-allofuranose
To overcome the aforementioned problems and to have an
easy access to both 1a and 1b through a single intermediate
we studied another sequence of reactions using two possible
starting materials 39 and 40 which were obtained by
displacing the leaving groups of 32 and 38, respectively by
sodium thiophenolate. Here also, for reasons discussed
above, the gluco-derivative 40 was the starting material of
choice over the allo-derivative 39 because methanolysis of
the latter generated more than six products as reported.16
The known mesylated allo-derivative 3821 was treated with
thiophenol in the presence of NaOMe in DMF to afford
sulfide derivative 40 with gluco-configuration. Compound
40 was deprotected and glycosylated in a single operation
by using acetyl chloride and MeOH to afford a mixture of
3-deoxy-3-phenylsulfide-hexopyranosides which were
collected as the benzylidene derivatives 42 and 43 in a
ratio 2.2:1 in good yields. The anomers 42 and 43 were
separated on silica gel column and were converted
separately to the corresponding sulfones 44 and 45 in
excellent yields using MMPP in MeOH. In an alternative
approach, compound 40 was oxidized with MMPP in
MeOH to the corresponding sulfone 41 in excellent yield.
Compound 41 was deprotected and glycosylated in the
presence of acetyl chloride and MeOH in one step to
generate a mixture of anomeric sulfones, which were
collected as the benzylidene gluco-derivatives 44 and 45,
respectively in good yields in a ratio 1:1.8. The anomers
were separated by column chromatography. Compounds 44
and 45 were mesylated separately and the mesylated
derivatives on treatment with DBU produced the desired
vinyl sulfone-modified hex-2-enopyranosides 1a and 1b,
respectively in excellent yields (Scheme 8).
The known tosylate 3217 was considered as a suitable
starting material17 because it could be easily converted to a
mixture of 33 and 34 (via deprotection, glycosylation
followed by benzylidenation) in a ratio 1:1.5.18 The
anomers were separated by column chromatography. The
b-anomer 34 was reacted with thiophenol in the presence of
NaOMe in DMF to afford sulfide derivative 35. Compound
35, on oxidation with MMPP in MeOH produced the sulfone
36. Compound 36 under mesylation condition generated
smoothly the desired vinyl sulfone 1b in overall 79% yield
(in 3 steps from 34) (Scheme 6). The a-anomer 33, when
treated with the sodium salt of thiocresol, produced an
undesired sulfide derivative 37. Since it was reported19 that
33 very easily formed the epoxide A, it is logical to
conclude that under the reaction conditions altro-derivative
37 was formed20 along with some other unidentified
products (Scheme 7). No further study was carried out on
2.7. Structural elucidation
The regio- and stereospecificities of attack of sodium
thiocresolate to C-3 positions of 5/6 and 11/12 were
determined by the configurations of the epoxide rings and
the anomeric configurations. It was, therefore a foregone
conclusion that the a-lyxo-epoxides 5/6 would produce
arabino-derivatives 7/8 and the b-ribo-epoxides would
generate xylo-derivatives 13/14. Similarly, backside attack
Scheme 6. Reagents and conditions: (a) PhSH, NaOMe, DMF, 135–1408C,
2.5–3 h, 90%; (b) MMPP, MeOH, room temperature, 3 h, 95%; (c) MsCl,
Py., 08C–room temperature, 4 h.

A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7207
a-D-xylofuranosides with free OH groups at C-2 position (d
3.44–3.47) were always more downfield than the corre-
sponding values of methyl b-D-ribofuranosides and b-D-
xylofuranosides (d 3.25–3.36). In the case of our compounds,
in a pair of anomers like 19 (d 3.49)/20 (d 3.34), 21 (d 3.49)/22
(d 3.26), 28 (d 3.50)/13 (d 3.36) and 29 (d 3.45)/15 (d 3.41)
a-methoxy protons always appeared at a more downfield
region. Interestingly, in the same pair of anomers the C-1
carbons of a-anomers 19, 21, 28 and 29 (d 101.2–103.2)
appeared at a more upfield region than those of b-anomers 20,
22, 13 and 15 (d 108.4–110.2). This observation is in
agreement with the report22e that the chemical shift values of
C-1 ranging from d 100.2–100.9 are characteristic of a-xylo-
configurations and those of b-xylo-derivatives have their
values ranging from d 107.8–109.8.
In the case of the pyranosyl compounds, 35 was the product
of the substitution reactions as expected, the undesired
altro-derivative 37 was obtained through a reported19,20
sequence of reactions. In the case of 42 and 43, C-S bonds at
C-3 and the gluco-configurations of the compounds were
predecided by selecting a starting thiosugar 40 which was
obtained from the known mesylate 38.
Scheme 8. Reagents and conditions: (a) PhSH, NaOMe, DMF, 120–1258C,
2–4 h, 40¼80% and 39¼90%; (b) (i) CH3COCl, anhydr. MeOH, reflux,
24 h; (ii) 1,1-dimethoxytoluene, p-TSA, DMF, 1008C, 1 h, 42þ43¼71%
(2.2:1) and 44þ45¼75% (1:1.8) (in two steps); (c) MMPP, MeOH, room
temperature, 2–3 h, 41¼94%, 44¼92%, 45¼90%; (d) (i) MsCl, Py., 08C,
12 h; (ii) DBU, CH2Cl2, room temperature, 15 min, 1a¼96%, 1b¼96% (in
two steps).
It is reported3,6a,23 that for methyl 4,6-O-(phenylmethyl-
ene)-a-D-hexopyranosides with D-gluco-and D-allo-con-
figurations, a coupling constant (J1,2) value of 3.3–3.8 Hz
is the characteristic of equatorial H-1/axial H-2 arrange-
ments. For b-series, in general a relatively large value of J1,2
(6.6–8.5 Hz) is characteristic of axial H-1/axial H-2
arrangement.22f,g Compounds 42 (3.5 Hz) and 44 (3.4 Hz)
are concluded as having a-gluco-configuration and 43
(7.3 Hz) and 45 (6.9 Hz) are regarded as possessing
b-gluco-configuration. Similarly, by comparison, it was
inferred that compound 37 (0.0 Hz) is having a-altro-
configuration and compounds 35 (8.3 Hz) and 36 (8.3 Hz)
are having b-allo-configurations.
of sodium thiocresolate at the C-3 positions of 17, 26 and
30/31 would afford products 18, 27 and 19/20, respectively.
In a similar fashion, 38 produced the gluco-derivative 40.
However, additional support for the structures, especially
the relationships between H-1 and H-2 protons came from
the analysis of the 1H NMR spectrum. It is well documented
in the literature22 that for methyl a-D-pentofuranosides with
It is also evident from literature22 that in general a-anomeric
methyl glycofuranosides show high and positive optical
rotation values while b-anomeric methyl glycosides render
either very small positive or negative values. In our case,
methyl a-D-ribofuranosides, 18 (þ100.1), 19 (þ145.1), 21
(þ100.9) and 26 (þ88.2) have shown positive rotations and
the corresponding b-intermediates 20 (240.5) and 22
(250.0) showed negative rotations. Methyl a-D-xylofurano-
sides 28 (þ163.7) and 29 (þ236.8) are having higher optical
rotations than the corresponding b-intermediates 13
(þ16.1) and 15 (þ17.2), respectively. Similarly, benzylated
or tritylated a-anomeric compounds 7 (þ128.8)/8 (þ74.2)
and 9 (þ95.2)/10 (þ81.7) with arabino-configuration were
showing higher rotation values than the b-anomeric
xylofuranosides 13 (þ16.1)/14 (þ56.9) and 15 (þ17.2)/16
(þ40.9) as expected from the literature. Among 1,2-O-
isopropylidene derivatives, intermediates with xylo-con-
figuration 17 (226.1) and 27 (231.0) showed negative
rotations whereas compounds 18 (þ100.1) and 26 (þ88.2)
with ribo-configuration showed positive rotations. In the
case of benzyl protected vinyl sulfone-modified carbo-
hydrates, the a-anomer 2a (þ5.9) is having higher rotation
than the corresponding b-isomer 2b (216.2) whereas the
tritylated a-anomer 3a (þ17.1) is having slightly higher
rotation than the b-anomer 3b (þ11.4).24
D-ribo- and D-xylo-configurations, a coupling constant (J1,2
)
value of 4.0–4.7 Hz is the characteristic of a cis-arrange-
ment for H-1 and H-2 and for methyl b-D-pentofuranoside
series with D-ribo- and D-xylo-configurations, a coupling
constant (J1,2) value of 0.0–2.0 Hz implies a trans-
arrangement of H-1 and H-2. Therefore, by comparing J1,2
values of our compounds with those of the reported
compounds, 19 (3.9 Hz) and 21 (4.9 Hz) were regarded as
possessing a-ribo-configurations and 28 (4.4 Hz)/29
(4.4 Hz) as having a-xylo-configurations. Similarly, by
comparing the J1,2 values of the corresponding b-series,
compounds 20 (0.0 Hz), 22 (0.0 Hz) were concluded as
having b-ribo-configurations and 13 (2.3 Hz), 15 (2.3 Hz),
14 (2.4 Hz) and 16 (3.0 Hz) as b-xylo-configurations.
Furthermore, for methyl a-D-pentofuranosides with ara-
bino- and lyxo-configurations, a coupling constant (J1,2
)
value of 0.0–3.0 Hz indicated the trans-orientation of H-1
and H-2. For b-series, a value of 3.0–5.0 Hz is character-
istic of a cis-arrangement for H-1 and H-2. Thus,
configurations of compounds 7 (0.0 Hz), 8 (0.0 Hz), 9
(0.0 Hz), and 10 (2.0 Hz) were assigned as having a-
arabino-configurations.
It is also evident from literature22 that the chemical shifts of
the methyl groups of methyl a-D-ribofuranosides as well as

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3. Conclusion
dryness under reduced pressure and the solid residue thus
obtained was dissolved in saturated NaHCO3. The aqueous
solution was washed with EtOAc (4£30 mL). The com-
bined organic layers were dried over anhydr. Na2SO4,
filtered and the filtrate was concentrated under reduced
pressure to get a residue. The residue was purified over
silica gel column to obtain the sulfones 9, 10, 15, 16, 21, 22,
29, 36, 41, 44 and 45.
Both a- and b-anomers of vinyl sulfone-modified
pent-2-enofuranosides 2 and 3 have been synthesized for
the first time using epoxides derived from carbohydrates as
starting materials as well as by taking advantage of the
formation of a- and b-methyl glycosides in almost equal
ratio only from derivatives of D-xylose. In the synthesis of
a- and b-anomers of vinyl sulfone-modified hex-2-eno-
pyranosides, a D-glucose derivative was selected over a
D-allose compound as the starting material because the
former almost exclusively produced the required methyl
pyranosides. Compounds 1a and 1b have been synthesized
earlier6a in a total of 15 steps from D-glucose (7 steps for 1a,
and 8 steps for 1b each). The present method makes use of
common intermediates up to compounds 44 and 45, thereby
drastically reducing the overall purification steps. Although
overall yields for both the methods are comparable, methyl
b-D-glucopyranoside, which has been used in the earlier
synthesis,6a is far too expensive as a starting material to be
used in a large-scale multi-step synthesis.
4.4. General procedure for the formation of 1, 2, 3
To a well stirred solution of the arylsulfonyl furanoses or
pyranoses in pyridine (5 mL/mmol) was added mesyl
chloride (4–6 equiv.) in pyridine (1 mL/mmol of MsCl)
dropwise at 08C under nitrogen. After completion of the
addition, the reaction mixture was kept at þ48C. After 24 h
(TLC), the reaction mixture was poured into ice-cold water
(10 mL/mmol of sugar) and aqueous layer was extracted
with CHCl3 (3£20 mL). The combined organic layers were
dried over anhydr. Na2SO4, filtered and the filtrate was
concentrated under reduced pressure. The crude material
was purified over silica gel column to get any of the title
compounds.
4. Experimental
4.4.1. Methyl 5-O-benzyl-2,3-dideoxy-3-C-(p)-tolylsul-
fonyl-a-D-erythro-pent-2-enofuranoside 2a. Compound
9 (0.48 g, 1.232 mmol) was converted to 2a following the
general procedure described above (0.38 g, 82%). Eluent:
EtOAc:pet ether (1:9). Brown gum. [a]2D5¼þ5.9 (c 0.927,
CHCl3). IR (CHCl3): 3444, 2358, 1953, 1892, 1776, 1724,
1596 cm21.1H NMR: d 7.78 (2H, d, J¼8.3 Hz, aromatic),
7.30 (7H, m, aromatic), 6.59 (1H, s), 5.88 (1H, d,
J¼4.4 Hz), 5.13 (1H, m), 4.44 (2H, s, PhCH2), 3.85 (1H,
dd, J¼10.7, 2.4 Hz), 3.60 (1H, dd, J¼10.7, 4.4 Hz), 3.39
(3H, s, OMe), 2.42 (3H, s, aromatic Me).13C NMR: d 147.2,
137.0, 145.3, 138.1, 136.4, 130.1, 128.3, 127.5, 107.5 (C-1),
83.6, 73.3 (CH2), 70.3 (CH2), 54.6 (OMe), 21.6 (aromatic
Me). MS: m/z (EI) 326 (0.4Mþ248), 251 (3), 236 (23), 219
(6), 139 (9), 105 (17), 91 (100), 77 (33), 65 (48). Anal. calcd
for C20H22O5S: C, 64.15; H, 5.91; S, 8.56. Found: C, 64.48;
H, 5.90; S, 8.67.
4.1. General methods
Melting points were determined in open-end capillary tubes
and are uncorrected. Carbohydrates and other fine chemicals
were obtained from commercial suppliers and are used
without purification. Solvents were dried and distilled
following the standard procedures.25 TLC was carried out
on precoated plates (Merck silica gel 60, f254) and the spots
were visualized with UV light or by charring the plate
dipped in 5% H2SO4–MeOH solution. Column chromato-
graphy was performed on silica gel (60–120 or 230–400
1
mesh). H NMR spectra were recorded at Bruker AC 200,
MSL 300 or DRX 500 MHz in CDCl3 using the residual
CHCl3 as standard. 13C NMR spectra were recorded at 50.3
and 75 MHz in CDCl3 using the triplet centered at d 77.27
as the standard. Optical rotations were recorded at 589 nm.
4.4.2. Methyl 2,3-dideoxy-3-C-(p)-tolylsulfonyl-5-O-tri-
tyl-a-D-erythro-pent-2-enofuranoside 3a. Compound 10
(3.14 g, 5.77 mmol) was converted to 3a following the
general procedure described above (2.56 g, 84%). Eluent:
EtOAc:pet ether (1:4). Colorless hygroscopic gum.
[a]2D6¼þ17.1 (c 1.07, CHCl3). IR (CHCl3): 4214, 3479,
2401, 1596, 1490 cm21. 1H NMR: d 7.52 (2H, d, J¼8.3 Hz,
aromatic); 7.2 (17H, m, aromatic), 6.56 (1H, s, H-2), 5.90
(1H, d, J¼4.4 Hz, H-1), 5.02 (1H, m), 3.43 (1H, dd, J¼10.7,
2.4 Hz), 3.30 (3H, s, OMe), 3.08 (1H, dd, J¼10.8, 4.9 Hz),
2.32 (3H, s, aromatic Me). 13C NMR: d 147.5, 145.2, 143.9,
137.3, 136.3, 130.0, 128.8, 128.1, 127.8, 127.1, 107.5 (C-1),
86.9, 83.8, 64.7 (CH2), 54.2 (OMe), 21.7 (aromatic Me).
MS: m/z (EI) 449 (,2), 243 (100), 165 (66), 91 (30). Anal.
calcd for C32H30O5S.1H2O: C, 70.57; H, 5.54. Found: C,
70.60; H, 5.76.
4.2. General procedure for the synthesis of 7, 8, 13 and 14
To a well stirred solution of 5, 6, 11 or 12 in DMF (4 mL/
mmol) were added p-thiocresol (5 equiv.) and NaOMe
(4 equiv.) and the mixture was heated at 80–908C for 2.5–
3.5 h with stirring. After completion of the reaction (TLC),
the reaction mixture was poured into saturated solution of
NaCl (60 mL/mmol) and the product was extracted with
EtOAc. The combined organic layers were dried over
anhydr. Na2SO4, filtered and the filtrate was concentrated
under reduced pressure to get a gummy residue. The residue
was purified over silica gel column to obtain the title
compound.
4.3. General procedure for the MMPP oxidation
To a well-stirred solution of the arylsulfide furanoses or
pyranoses in distilled MeOH (20 mL/mmol) was added
MMPP (5 equiv.) and the mixture was stirred for 2–3 h.
After completion of the reaction (TLC), the solid mass was
filtered off through celite bed. The filtrate was evaporated to
4.4.3. Methyl 5-O-benzyl-2,3-dideoxy-3-C-(p)-tolylsul-
fonyl-b-D-erythro-pent-2-enofuranoside 2b. Compound
15 (0.25 g, 0.637 mmol) was converted to 2b following
the general procedure described above (0.21 g, 87%).

A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7209
Eluent: EtOAc:pet ether (1:3). Brown gum. IR (CHCl3):
1722, 1596, 1494 cm21. [a]D26¼216.2 (c 1.004, CHCl3). 1H
NMR: d 7.75 (2H, d, J¼8.3 Hz, aromatic), 7.30 (7H, m,
aromatic), 6.60 (1H, s), 5.72 (1H, s), 4.95 (1H, d, J¼6.3 Hz),
4.47 (2H, s, PhCH2), 3.83 (1H, dd, J¼10.7, 2.4 Hz), 3.50
(1H, m), 3.42 (3H, s, OMe), 2.43 (3H, s, aromatic Me). 13C
NMR: d 147.6, 136.6, 145.3, 138.2, 136.3, 130.0, 128.3,
127.5, 107.3 (C-1), 83.4, 73.2 (CH2), 72.0 (CH2), 55.3
(OMe), 21.6 (aromatic Me). MS: m/z (EI) 250 (6Mþ2124),
236 (91Mþ2138), 218 (13Mþ2156), 139 (16), 105 (17),
91 (100), 77 (30), 65 (46). Anal. calcd for C20H22O5S:
C, 64.15; H, 5.91; S, 8.56. Found: C, 64.41; H, 6.36; S,
8.81.
129.7, 128.6, 127.8, 127.0, 109.4, 87.1, 83.1, 81.3, 63.8
(CH2), 54.9 (OMe), 53.5, 20.9 (aromatic Me). MS: m/z (EI)
512 (4Mþ), 270 (2), 259 (2), 251 (3), 244 (8), 243 (100).
Anal. calcd for C32H32O4S.1H2O: C, 72.43; H, 6.07; S, 6.04.
Found: C, 72.25; H, 6.45; S, 5.73.
4.4.7. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfonyl-
a-D-arabinofuranoside 9. Compound
7
(0.59 g,
1.652 mmol) was converted to 9 following the general
procedure described above (0.6 g, 93%). Eluent: EtOAc:pet
ether (1:4). Brown gum. [a]2D6¼þ95.2 (c 1.00, CHCl3). IR
(Neat on KBr plate): 3481, 3062, 3030, 2925, 1596, 1494,
1454, 1402, 1363 cm21. 1H NMR: d 7.73 (2H, d, J¼8.3 Hz,
aromatic), 7.29 (7H, m, aromatic), 4.86 (1H, s, H-1), 4.48
(5H, m), 3.69 (2H, m), 3.33 (1H, dd, J¼11.3 (10.8), 3.9
(3.4) Hz), 3.25 (3H, s, OMe), 2.39 (3H, s, aromatic Me). 13C
NMR: d 144.9, 137.3, 134.9, 129.6, 128.3, 128.1, 127.5,
108.9, 77.2, 77.0, 73.1 (CH2), 71.0, 69.4 (CH2), 54.5 (OMe),
21.2 (aromatic Me). MS: m/z (EI) 392 (,1.0Mþ), 343 (0.3),
301 (0.4), 271 (0.6), 262 (1.2), 243 (0.9), 205 (4), 155 (7),
107 (32), 92 (14), 91 (100). Anal. calcd for
C20H24O6S.0.25H2O: C, 60.50; H, 6.21; S, 8.07. Found:
C, 60.43; H, 6.46; S, 8.21.
4.4.4. Methyl 2,3-dideoxy-3-C-(p)-tolylsulfonyl-5-O-tri-
tyl-b-D-erythro-pent-2-enofuranoside 3b. Compound 16
(0.46 g, 0.838 mmol) was converted to 3b following the
general procedure described earlier (0.37 g, 84%). Eluent:
EtOAc:pet ether (1:4). White needle shaped crystal. Mp:
131–1328C. [a]2D6¼þ11.4 (c 1.012, CHCl3). IR (Nujol):
3097, 3051, 3028, 1593, 1490, 1463, 1448, 1377 cm21. 1H
NMR: d 7.53 (2H, d, J¼8.3 Hz, aromatic), 7.42 (6H, dd,
J¼8.3, 2.4 Hz, aromatic), 7.34–7.25 (9H, m, aromatic),
7.17 (2H, d, J¼7.8 Hz, aromatic), 6.64 (1H, t, J¼1.5,
1.4 Hz, H-2), 5.78 (1H, s, H-1), 5.00 (1H, d, J¼6.8 Hz), 3.48
(3H, s, OMe), 3.37 (1H, dd, J¼10.3, 2.0 Hz), 3.09 (1H, dd,
J¼10.3, 6.8 Hz), 2.41 (3H, s, aromatic Me). 13C NMR: d
147.4, 145.1, 143.9, 136.9, 136.2, 130.1, 128.9, 128.0,
127.1, 107.7 (C-1), 86.7, 83.7, 66.0 (CH2), 55.9, 21.7
(aromatic Me). MS: m/z (EI) 526 (0.1Mþ), 494 (0.1), 450
(0.8), 449 (0.9), 267 (0.9), 243 (100), 165 (36), 91 (16), 77
(9). Anal. calcd for C32H30O5S: C, 72.98; H, 5.73. Found: C,
73.12; H, 5.72.
4.4.8. Methyl 3-deoxy-3-C-(p)-tolylsulfonyl-5-O-trityl-a-
(3.82 g,
D-arabinofuranoside
10.
Compound
8
7.460 mmol) was converted to 10 following the general
procedure described above (3.31 g, 81%). Eluent: EtOAc:
pet ether (3:7). White needle shaped solid. Mp: 70–718C.
[a]2D5¼þ81.7 (c 1.01, CHCl3). IR (CHCl3): 3479, 1637,
1596, 1492 cm21
.
1H NMR: d 7.62 (2H, d, J¼8.3 Hz,
aromatic), 7.29 (17H, m, aromatic), 5.03 (1H, d, J¼2.0 Hz,
H-1), 4.64 (1H, m), 4.49 (1H, m), 3.80 (1H, m), 3.45 (1H,
dd, J¼10.8, 2.0 Hz), 3.37 (3H, s, OMe), 2.73 (2H, m), 2.42
(3H, s, aromatic Me). 13C NMR: d 145.1, 143.7, 135.3,
130.0, 128.7, 128.5, 127.9, 127.2, 109.0, 86.9, 77.3, 71.4,
63.9 (CH2), 55.3, 21.7 (aromatic Me). MS: m/z (EI) 287 (1),
259 (1), 244 (6), 243 (100), 228 (3), 165 (19). Anal. calcd
for C32H32O6S.1H2O: C, 68.31; H, 5.72; S, 5.69. Found: C,
68.01; H, 5.62; S, 6.78.
4.4.5. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfide-a-
D-arabinofuranoside 7. Compound 5 (0.57 g, 2.43 mmol)
was converted to 7 following the general procedure
described above (0.81 g, 92%). Eluent: EtOAc:pet ether
(1:4). Brown oil. [a]2D6¼þ128.8 (c 1.00, CHCl3). IR (neat on
KBr plate): 3438, 3062, 3030, 2866, 2833, 1596, 1494,
1454, 1400 cm21. 1H NMR: d 7.30 (7H, m, aromatic), 7.06
(2H, d, J¼8.3 Hz, aromatic), 4.92 (1H, s, H-1), 4.61 (1H, d,
J¼12.2 Hz), 4.48 (1H, d, J¼11.8 Hz), 4.42 (1H, m), 4.13
(1H, d, J¼10.0 Hz), 3.77 (1H, dd, J¼10.7, 2.0 Hz), 3.56
(1H, d, J¼9.8 Hz), 3.44 (2H, m), 3.38 (3H, s, OMe), 2.29
(3H, s, aromatic Me). 13C NMR: d 137.2, 136.6, 131.1,
129.5, 128.1, 127.5, 109.4 (C-1), 82.9, 81.0, 73.0 (CH2),
69.4 (CH2), 54.6 (OMe), 52.9, 20.6 (aromatic Me). MS: m/z
(EI) 360 (9Mþ), 328 (2), 221 (1), 189 (1), 179 (3), 165 (5),
124 (39), 91 (100). Anal. calcd for C20H24O4S: C, 66.64; H,
6.70; S, 8.89. Found: C, 66.34; H, 7.34: S, 8.89.
4.4.9. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfide-b-
D-xylofuranoside 13. Compound 11 (0.44 g, 1.851 mmol)
was converted to 13 following the general procedure
described above (0.53 g, 79%). Eluent: EtOAc:pet ether
(1:9). Brown gum. [a]3D0¼þ16.1 (c 1.04, CHCl3). IR (neat):
3425, 3062, 3031, 2923, 2862 cm21. 1H NMR: d 7.28 (7H,
m, aromatic), 7.03 (2H, d, J¼8.3 Hz, aromatic), 4.81 (1H, d,
J¼1.9 Hz, H-1), 4.60 (1H, m), 4.54 (2H, s, PhCH2), 4.25
(1H, dd, J¼4.9, 1.9 Hz), 3.76–3.63 (3H, 2£m), 3.36 (3H, s,
OMe), 3.25 (1H, broad hump, OH), 2.27 (3H, s, aromatic
Me). 13C NMR: d 138.0, 136.0, 132.2, 130.3, 129.7, 128.1,
127.7, 127.4, 109.4 (C-1), 81.1, 79.9, 73.1 (CH2), 71.2
(CH2), 55.3 (OMe), 54.7, 20.8 (aromatic Me). MS: m/z (EI)
360 (11Mþ), 328 (11), 149 (20), 135 (15), 124 (41), 91
(100). Anal. calcd for C20H24O4S: C, 66.64; H, 6.70; S,
8.89. Found: C, 66.32; H, 7.24; S, 8.81.
4.4.6. Methyl 3-deoxy-3-C-(p)-tolylsulfide-5-O-trityl-a-
D-arabinofuranoside 8. Compound 6 (5.1 g, 13.13 mmol)
was converted to 8 following the general procedure
described above (4.61 g, 69%). Eluent: EtOAc:pet ether
(3:7). Colorless gum. [a]2D5¼þ74.2 (c 1.09, CHCl3). IR
1
(CHCl3): 3442, 2831, 1666, 1492 cm21. H NMR: d 7.28
(17H, m, aromatic), 6.98 (2H, d, J¼8.3 Hz, aromatic), 4.99
(1H, s, H-1), 4.15 (2H, a broad hump), 3.56 (1H, dd, J¼10.3,
2.5 Hz), 3.39 (3H, s, OMe), 3.35 (1H, m), 3.05 (1H, dd,
J¼11.3, 4.0 Hz), 2.80 (1H, d, J¼2.5 Hz, OH), 2.27 (3H, s,
aromatic Me). 13C NMR: d 143.5, 136.8, 131.4, 131.2,
4.4.10. Methyl 3-deoxy-3-C-(p)-tolylsulfide-5-O-trityl-b-
D-xylofuranoside 14. Compound 12 (1.3 g, 3.37 mmol) was
converted to 14 following the general procedure described
above (1.64 g, 95%). Eluent: EtOAc:pet ether (1:9). White
plate shaped solid. Mp: 114–1158C. [a]2D6¼þ56.9 (c 1.008,

7210
A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
CHCl3). IR (CHCl3): 4212, 3608, 3431, 2399, 1492,
1
(2H, d, J¼2.9 Hz, PhCH2), 4.16 (1H, m), 3.80 (1H, dd,
J¼11.2, 1.5 Hz), 3.53 (2H, m), 2.32 (3H, s, aromatic Me),
1.56 (3H, s, Me), 1.37 (3H, s, Me). 13C NMR: d 137.9,
137.0, 131.9, 129.6, 128.0, 127.3, 111.8, 104.1, 81.3, 73.1
(PhCH2), 67.6 (CH2), 50.7, 26.5 (Me), 26.3 (Me), 20.8
(aromatic Me). MS: m/z (EI) 386 (18Mþ), 328 (20), 207
(33), 163 (20), 123 (75), 91 (100). Anal. calcd for
C22H26O4S: C, 68.36; H, 6.77; S, 8.29. Found: C, 68.25;
H, 6.87; S, 8.62.
1448 cm21. H NMR: d 7.51 (6H, d, J¼6.8 Hz, aromatic),
7.25 (10H, m, aromatic), 7.02 (3H, dd, J¼26.3, 7.8 Hz,
aromatic), 4.88 (1H, d, J¼2.4 Hz, H-1), 4.57–4.49 (1H, m),
4.35 (1H, bs), 3.58 (1H, t, J¼6.9, 5.8 Hz), 3.43 (3H, s,
OMe), 3.41–3.32 (2H, m), 2.65 (1H, J¼4.4 Hz, OH), 2.25
(3H, s, aromatic Me). 13C NMR: d 144.2, 137.1, 132.1,
131.4, 129.9, 129.0, 127.8, 127.4, 109.6 (C-1), 87.1, 88.9,
81.2, 65.3 (CH2), 55.9, 55.6, 21.1 (aromatic Me). MS: m/z
(EI) 512 (2Mþ), 269 (30), 243 (100). Anal. calcd for
C32H32O4S: C, 74.97; H, 6.28; S, 6.25. Found: C, 75.00; H,
6.21; S, 6.22.
4.4.14. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfide-
a-D-ribofuranoside 19 and methyl 5-O-benzyl-3-deoxy-
3-C-(p)-tolylsulfide-b-D-ribofuranoside 20. A solution of
18 (2.08 g, 5.39 mmol) and conc. H2SO4 (1 mL) in dry
MeOH (30 mL) was heated under reflux in an inert
atmoshphere. After 3.5 h, the reaction mixture was cooled
to room temperature and neutralized by BaCO3. The
mixture was evaporated to dryness under reduced pressure
and the residue was triturated with EtOAc (3£40 mL). The
mixture was filtered through celite and the combined
filtrates were concentrated to dryness under reduced
pressure. Purification of the gummy residue over silica gel
using EtOAc:pet ether (4:21) furnished a mixture of 19 and
20 (1.52 g, 78%). Compound 19 and 20 were isolated as
colorless thick gum.
4.4.11. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfonyl-
b-D-xylofuranoside 15. Compound 13 (0.4 g, 1.11 mmol)
was converted to 15 following the general procedure
described above (0.39 g, 89%). Eluent: EtOAc:pet ether
(3:7). Brown gum. [a]2D7¼þ17.2 (c 1.10, CHCl3). IR
1
(CHCl3): 3479, 3087, 3062, 3029, 2927, 2869 cm21. H
NMR: d 7.75 (2H, d, J¼8.0 Hz, aromatic), 7.31 (7H, m,
aromatic), 4.87 (1H, d, J¼2.3 Hz, H-1), 4.74 (1H, dd,
J¼8.0, 2.0 Hz), 4.58 (2H, s, PhCH2), 4.48 (1H, m), 3.91
(3H, m), 3.41 (3H, s, OMe), 3.00 (1H, bs, OH), 2.42 (3H, s,
aromatic Me). 13C NMR: d 144.9, 137.8, 136.2, 129.7,
128.0, 127.5, 127.3, 110.2 (C-1), 78.1, 76.2, 73.1 (CH2),
71.3, 69.8 (CH2), 55.6 (OMe), 21.2 (aromatic Me). MS: m/z
(EI) 392 (,1Mþ), 360 (6), 205 (9), 187 (9), 155 (20), 139
(22), 107 (33), 99 (32), 99 (100). Anal. calcd for
C20H24O6S: C, 61.20; H, 6.16. Found: C, 61.37; H, 5.89.
Compound 19 (0.05 g, 2.6%). Brown gum. [a]2D6¼þ145.1 (c
1.024, CHCl3). IR (CHCl3): 3523, 1492 cm21. 1H NMR: d
7.31 (7H, m, aromatic), 7.08 (2H, d, J¼8.3 Hz, aromatic),
4.97 (1H, d, J¼3.9 Hz), 4.53 (2H, m, PhCH2), 4.39 (1H, m),
4.25 (1H, m), 3.61 (3H, m), 3.49 (3H, s, OMe), 3.2 (1H, d,
J¼9.8 Hz, OH), 2.33 (3H, s, aromatic Me).13C NMR: d
138.3, 137.3, 132.7, 131.7, 130.0, 128.6, 127.8, 103.2 (C-1),
82.9, 73.8 (CH2), 71.9, 70.4 (CH2), 55.5 (OMe), 52.8, 21.2
(aromatic Me). MS: m/z (EI) 360 (3Mþ), 328 (2), 163 (4),
124 (38), 91 (100). Anal. calcd for C20H24O4S: C, 66.64; H,
6.70; S, 8.89. Found: C, 66.90; H, 6.72; S, 9.05.
4.4.12. Methyl 3-deoxy-3-C-(p)-tolylsulfonyl-5-O-trityl-
b-D-xylofuranoside 16. Compound 14 (1.38 g, 2.69 mmol)
was converted to 16 following the general procedure
described above (1.08 g, 74%). Eluent: EtOAc:pet ether
(1:3). White needle shaped solid. Mp: 74–758C.
[a]2D6¼þ40.9 (c 1.00, CHCl3). IR (Nujol): 3469, 1596,
1490, 1463, 1448, 1377 cm21. 1H NMR: d 7.51–7.20 (19H,
a broad multiplet, aromatic), 4.94 (1H, d, J¼3.0 Hz, H-1),
4.75 (1H, dd, J¼2.5(3.0), 7.8(8.3) Hz), 4.34 (1H, m), 3.83
(1H, t, J¼58.3, 7.8 Hz), 3.42–3.64 (2H, m), 3.46 (3H, s,
OMe), 2.82 (1H, bs, OH), 2.43 (3H, s, aromatic Me). 13C
NMR: d 145.8, 144.5, 136.7, 130.7, 129.5, 128.6, 128.4,
127.6, 110.9, 87.5, 79.2, 77.2, 72.2, 64.5 (CH2), 56.8, 21.8
(aromatic Me). MS: m/z (EI) 544 (1Mþ), 470 (2), 405 (2),
360 (3), 243 (100). Anal. calcd for C32H32O6S.2H2O: C,
66.18; H, 6.24; S, 5.52. Found: C, 66.28; H, 6.30; S, 5.93.
Compound 20 (1.07 g, 55%). Brown gum. [a]2D6¼240.5 (c
1.01, CHCl3). IR (CHCl3): 3444, 1951, 1888, 1598 cm21
.
1H NMR: d 7.35 (7H, m, aromatic), 7.11 (2H, d, J¼7.9 Hz,
aromatic), 4.98 (1H, s, H-1), 4.64 (2H, s, PhCH2), 4.17 (1H,
m), 3.98 (1H, dd, J¼3.9, 1.4 Hz), 3.71 (4H, m), 3.34 (3H, s,
OMe), 2.90 (1H, d, J¼1.5 Hz, OH), 2.33 (3H, s, aromatic
Me). 13C NMR: d 138.5, 138.0, 132.1, 130.2, 129.9, 128.5,
127.6, 108.4 (C-1), 81.7, 74.9, 73.4 (CH2), 71.8 (CH2), 54.7
(OMe), 53.5, 21.1 (aromatic Me). MS: m/z (EI) 360 (13Mþ),
328 (4), 124 (23), 123 (18), 91 (100). Anal. calcd for
C20H24O4S: C, 66.64; H, 6.70; S, 8.89. Found: C, 66.80; H,
7.00; S, 8.82.
4.4.13. 5-O-Benzyl-3-deoxy-1,2-O-isopropylidene-3-C-
(p)-tolylsulfide-a-D-ribofuranose 18. To a well stirred
solution of NaOMe (1.98 g, 36.79 mmol) in DMF (40 mL)
was added p-thiocresol (5.7 g, 45.99 mmol) and the mixture
was stirred for 0.5 h. A solution of 17 (3.99 g, 9.19 mmol) in
DMF (20 mL) was added and the reaction mixture was then
heated at 1208C. After 4 h, the mixture was cooled to room
temperature and poured into brine (150 mL) solution. The
aqueous phase was extracted with EtOAc (5£30 mL). The
combined organic phases were dried over anhydr. Na2SO4,
filtered and the filtrate was concentrated to dryness under
reduced pressure. Purification of the crude product on silica
gel using EtOAc:pet ether (1:19) yielded 18 (2.08 g, 59%).
Brown gum. [a]2D6¼þ100.1 (c 1.02, CHCl3). IR (CHCl3):
1492, 1454, 1384 cm21. 1H NMR: d 7.28 (9H, m, aromatic);
5.84 (1H, d, J¼3.4 Hz, H-1), 4.80 (1H, t, J¼3.9 Hz), 4.37
4.4.15. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfonyl-
a-D-ribofuranoside
21.
Compound
19
(0.05 g,
0.127 mmol) was converted to 21 following the general
procedure described above (0.04 g, 94%). Eluent: EtOAc:
pet ether (3:7). Brown gum. [a]2D6¼þ100.9 (c 1.006,
CHCl3). IR (CHCl3): 4214, 3531, 2401, 2343, 1730,
1
1596 cm21. H NMR: d 7.77 (2H, d, J¼8.3 Hz, aromatic),
7.31 (7H, m, aromatic), 4.95 (1H, d, J¼4.9 Hz, H-1), 4.72
(1H, dq, J¼2.9, 2.0 Hz), 4.59 (1H, d, J¼12.2 Hz, PhCH),
4.46 (1H, d, J¼12.2 Hz, PhCH), 4.33–4.45 (1H, m), 3.93
(1H, m), 3.65 (1H, dd, J¼10.7, 1.9 Hz), 3.45–3.52 (5H, m),
2.43 (3H, s, aromatic Me). 13C NMR: d 144.8, 137.8, 136.9,

A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7211
129.6, 128.7, 128.4, 127.7, 101.9 (C-1), 76.1, 73.5 (CH2),
72.1, 69.5 (CH2), 62.9, 55.3 (OMe), 21.6 (aromatic Me).
MS: m/z (EI) 360 (0.6Mþ2O2), 205 (6.7), 175 (1.3), 155
(4.0), 139 (4.3), 117 (2.0), 91 (100). Anal. calcd for
C20H24O6S: C, 61.20; H, 6.16; S, 8.17. Found: C, 61.21; H,
6.23; S, 8.09.
procedure for the synthesis of 18. The reaction mixture
was heated at 135–1408C for 2.5–3 h (2.43 g, 79%).
Eluent: EtOAc:pet ether (1:21). Brown gum. [a]3D0¼231.0
1
(c 1.00, CHCl3). IR (CHCl3): 2985, 2931, 1496 cm21. H
NMR: d 7.36 (7H, m, aromatic), 7.14 (2H, d, J¼7.8 Hz,
aromatic), 5.94 (1H, d, J¼3.4 Hz, H-1), 4.70–4.53 (4H, m),
3.83 (2H, d, J¼5.9 Hz, PhCH2), 3.76 (1H, d, J¼3.9 Hz),
2.53 (3H, s, aromatic Me), 1.53 (3H, s, Me), 1.29 (3H, s,
Me). 13C NMR: d 137.9, 136.8, 130.8 129.8, 128.1, 127.6,
111.5, 104.7, 85.2, 77.9, 73.3 (CH2), 69.2 (CH2), 54.2, 26.5,
26.2, 20.8 (aromatic Me). MS: m/z (EI) 386 (19Mþ), 233
(10), 207 (24), 205 (10), 178 (20), 139 (14), 124 (14), 123
(40), 107 (14), 99 (16), 91 (100). Anal. calcd for
C22H26O4S: C, 68.36; H, 6.77; S, 8.29. Found: C, 68.03;
H, 7.23; S, 8.29.
4.4.16. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfonyl-
b-D-ribofuranoside 22. Compound 20 (0.95 g, 2.64 mmol)
was converted to 22 following the general procedure
described above (0.96 g, 93%). Eluent: EtOAc:pet ether
(1:3). Brown needle shaped solid. Mp: 79–808C.
[a]2D6¼250.0 (c 1.00, CHCl3). IR (CHCl3): 4214, 3479,
2401, 1596 cm21
.
1H NMR: d 7.80 (2H, d, J¼8.1 Hz,
aromatic), 7.32 (7H, m, aromatic), 4.93 (1H, m), 4.84 (1H, s,
H-1), 4.54 (2H, d, J¼5.5 Hz, PhCH2), 4.15 (1H, t,
J¼4.3 Hz), 3.87 (2H, m), 3.72 (1H, dd, J¼10.7, 2.2 Hz),
3.52 (1H, dd, J¼10.7, 5.5 Hz), 3.26 (3H, s, OMe), 2.45 (3H,
s, aromatic Me). 13C NMR: d 145.5, 138.1, 136.4, 130.0,
128.2, 127.5, 108.4 (C-1), 77.1, 75.5, 73.3 (CH2), 72.0
(CH2), 65.1, 54.4 (OMe), 21.6 (aromatic Me). MS: m/z (EI)
360 (0.5Mþ2MeOH), 271 (0.3), 243 (0.4), 205 (10), 155
(6), 107 (10), 91 (100). Anal. calcd for C22H24O6S: C,
61.20; H, 6.16; S, 8.17. Found: C, 61.06; H, 6.38; S, 8.47.
4.4.21. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfide-
a-D-xylofuranoside 28 and methyl 5-O-benzyl-3-deoxy-
3-C-(p)-tolylsulfide-b-D-xylofuranoside 13. A solution of 27
(2.43 g, 6.29 mmol) and conc. H2SO4 (1 mL) in dry MeOH
(70 mL) was heated under reflux. After 2.5 h, the reaction
mixture was worked up as described for 19 and 20. The
anomers were separated on silica gel using EtOAc:pet ether
(1:3) to give 28 and 13. Compound28 (1.2 g, 53%). Yellowish
gum. [a]3D0¼þ163.7 (c 1.13, CHCl3). IR (neat): 3487, 3062,
3024, 2916, 1862 cm21. 1H NMR: d 7.37 (7H, m, aromatic),
7.10 (2H, d, J¼8.3 Hz, aromatic), 4.98 (1H, d, J¼4.4 Hz, H-
1), 4.60 (1H, m), 4.60 (2H, d, J¼11.2 Hz, PhCH2), 4.29 (1H,
dd, J¼8.0, 4.6 Hz), 3.78 (2H, d, J¼3.9 Hz), 3.65 (1H, t,
J¼7.8 Hz), 3.50 (3H, s, OMe), 2.76 (1H, bs, OH), 2.34 (3H, s,
aromatic Me).13C NMR: d 137.7, 136.0, 132.3, 130.2, 129.4,
128.0, 127.3, 127.1, 101.2 (C-1), 77.4, 76.3, 72.9 (CH2), 70.2
(CH2), 55.0 (OMe), 54.0, 20.5 (aromatic Me). MS: m/z (EI)
360 (13Mþ), 159 (11), 149 (11), 124 (100), 91 (61). Anal.
calcd for C20H24O4S: C, 66.64; H, 6.70. Found: C, 66.57; H,
7.07. Compound 13 (0.81 g, 36%).
4.4.17. Methyl 5-O-benzyl-2,3-dideoxy-3-C-(p)-tolyl-
sulfonyl-a-D-erythro-pent-2-enofuranoside 2a. Com-
pound 21 (0.38 g, 0.977 mmol) was converted to 2a
following the general procedure described above (0.27 g,
74%). The reaction mixture was kept at þ48C for 12 h and
then it was stirred for 8 h at ambient temperature.
4.4.18. Methyl 5-O-benzyl-2,3-dideoxy-3-C-(p)-tolyl-
sulfonyl-b-D-erythro-pent-2-enofuranoside 2b. Com-
pound 22 (0.369 g, 0.941 mmol) was converted to 2b
following the general procedure described above (0.32 g,
92%).
4.4.22. Methyl 5-O-benzyl-3-deoxy-3-C-(p)-tolylsulfonyl-
a-D-xylofuranoside 29. Compound 28 (0.62 g, 1.72 mmol)
was converted to 29 following the general procedure
described above (0.61 g, 90%). Eluent: EtOAc:pet ether
(3:7). White needle shaped solid. Mp: 127–1288C.
[a]2D7¼þ236.8 (c 1.00, CHCl3). IR (CHCl3): 3487, 2954,
4.4.19. 5-O-Benzyl-1,2-O-isopropylidene-3-O-mesyl-a-D-
ribofuranose 26. To a stirred solution of 25 (0.32 g,
1.14 mmol) was added a solution of mesyl chloride (0.3 mL,
3.42 mmol) in dry pyridine (10 mL) dropwise at 08C under
nitrogen atmosphere. After completion of addition, the
reaction mixture was kept at þ48C for 24 h. The reaction
mixture was worked up as per the procedure mentioned for
17 to obtain an oil which was purified over silica gel using
EtOAc:pet ether (1:4) to afford 26 (0.4 g, 98%). Brown oil.
[a]2D6¼þ88.2 (c 1.07, CHCl3). IR (CHCl3): 3446, 2343,
2923, 2854 cm21
.
1H NMR: d 7.79 (2H, d, J¼7.8 Hz,
aromatic), 7.36 (7H, m, aromatic), 4.98 (1H, d, J¼4.4 Hz,
H-1), 4.62 (4H, m), 4.09 (2H, m), 3.74 (1H, t, J¼7.8 Hz),
3.45 (3H, s, OMe), 3.00 (1H, bs, OH), 2.42 (3H, s, aromatic
Me). 13C NMR: d 145.1, 138.2, 136.6, 129.9, 129.0, 128.0,
127.9, 101.3 (C-1), 76.6, 73.9, 73.6 (CH2), 69.7 (CH2), 69.4,
55.6 (OMe), 21.7 (aromatic Me). MS: m/z (EI) 392
(,1Mþ), 360 (5Mþ2O2), 115 (10), 139 (11), 107 (10),
99 (16), 99 (100). Anal. calcd for C20H24O6S: C, 61.20; H,
6.16. Found: C, 61.07; H, 6.05.
1
1417, 1373, 1365 cm21. H NMR: d 7.43–7.26 (5H, m),
5.85 (1H, d, J¼3.9 Hz, H-1), 4.87 (1H, m), 4.77 (1H, t,
J¼3.9 (4.4) Hz), 4.65 (1H, d, J¼12.2 Hz), 4.56 (1H, d,
J¼11.7 Hz), 4.26 (1H, dt, J¼3.4 (3.8), 3.0 Hz), 3.76 (1H,
dd, J¼11.7, 2.4 Hz), 3.65 (1H, dd, J¼11.7, 3.4 Hz), 3.05
(3H, s, OMe), 1.58 (3H, s, Me), 1.38 (3H, s, Me). 13C NMR:
d 137.7, 128.5, 127.8, 113.5, 104.1, 77.3, 76.6, 75.8, 73.7
(CH2), 67.0 (CH2), 38.3, 26.6. MS: m/z (EI) 358 (14Mþ),
343 (6), 237 (7), 179 (23), 175 (13), 151 (14), 107 (22), 91
(100), 85 (18). Anal. calcd for C16H22O7S: C, 53.62; H,
6.18; S, 8.94. Found: C, 53.62; H, 6.17; S, 8.72.
4.4.23. Methyl 5-O-benzyl-2,3-dideoxy-3-C-(p)-tolyl-
sulfonyl-a-D-erythro-pent-2-enofuranoside 2a. Com-
pound 29 (0.5 g, 1.27 mmol) was converted to 2a
following the general procedure (0.36 g, 76%).
Compound 19 from 30. Compound 30 (1.71 g, 4.196 mmol)
was converted to 19 following a procedure described for the
synthesis of 18. The reaction mixture was heated at 115–
1208C for 3.5 h (1.33 g, 88%).
4.4.20. 5-O-Benzyl-3-deoxy-1,2-O-isopropylidene-3-C-
(p)-tolylsulfide-a-D-xylofuranose 27. Compound 26
(2.84 g, 7.93 mmol) was converted to 27 following a

7212
A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
Compound 20 from 31. Compound 31 (1.15 g, 3.705 mmol)
was converted to 20 following a procedure described for the
synthesis of 18. The reaction mixture was heated at 115–
1208C for 3 h (1.11 g, 83%).
(0.17 g, 0.407 mmol) was converted to 37 following a
procedure reported for 35 (0. 06 g, 39%). Eluent: EtOAc:pet
ether (1:4). Colorless gum. IR (CHCl3): 3500, 2360, 2331,
1671, 1583 cm21. 1H NMR: d 7.32 (10H, m, aromatic), 5.61
(1H, s, PhCH), 4.81 (1H, s, H-1), 4.22 (3H, m), 4.04 (1H, dd,
J¼9.8, 3.0 Hz), 3.81 (1H, t, J¼8.3 Hz), 3.58 (1H, d,
J¼2.4 Hz), 3.35 (3H, s, OMe), 3.09 (1H, d, J¼5.8 Hz,
OH). 13C NMR: d 137.3, 133.9, 131.0, 129.4, 129.1, 128.2,
127.6, 126.3, 102.2, 101.3, 76.4, 69.1 (CH2), 68.8, 58.6,
55.7 (OMe), 51.6. MS: m/z (EI) 374 (36Mþ), 343 (4), 165
(88), 152 (88), 123 (42), 105 (82), 91 (100), 77 (90). Anal.
calcd for C20H22O5S: C, 64.15; H, 5.91; S, 8.56. Found: C,
63.90; H, 6.23; S, 8.27.
Compounds 19 and 20 from the mixture of 30 and 31. A
mixture of compounds 30 and 31 (3.99 g, 9.19 mmol) was
converted to the mixture of 19 and 20 following the
procedure described for the synthesis of 18 (2.09 g, 94%).
4.4.24. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsulfide-b-D-allopyranoside 35. To a well stirred
solution of NaOMe (0.506 g, 9.38 mmol) in DMF (10 mL)
was added dropwise thiophenol (1.2 mL, 11.726 mmol)
under nitrogen at ambient temperature. After 15 min, 34
(0.98 g, 2.345 mmol) in DMF (20 mL) was added into the
mixture and the mixture was heated at 135–1408C. After
2 h, the mixture was cooled to room temperature, poured
into brine (150 mL) and the aqueous phase was extracted
with EtOAc (4£40 mL). The combined extracts were dried
over anhydr. Na2SO4, filtered and the filtrate was evaporated
to dryness under reduced pressure to get the crude material.
Purification of the crude material over silica gel using
EtOAc:pet ether (1:4) produced the title compound (0.79 g,
90%). White solid. Mp: 133–1348C. [a]2D6¼240.5 (c 1.00,
4.4.28. 3-Deoxy-1,2:5,6-di-O-isopropylidene-3-C-phenyl-
sulfide-a-D-allofuranose 39. Compound 32 (10.72 g,
25.88 mmol) was converted to 39 following the procedure
reported for 35 (8.23 g, 90%). The reaction mixture was
heated at 1258C for 4 h. Eluent: EtOAc:pet ether (1:9).
Colorless needle shaped solid. Mp: 84–858C. IR (Nujol):
1647, 1461 cm21
.
1H NMR: d 7.50 (2H, d, J¼5.9 Hz,
aromatic), 7.28 (3H, m, aromatic), 5.81 (1H, d, J¼3.4 Hz,
H-1), 4.77 (1H, t, J¼4.4, 3.9 Hz), 4.17–4.45 (2H, m), 4.04
(1H, t, J¼6.8, 9.3 Hz), 3.92 (1H, t, J¼7.9, 6.8 Hz), 3.29 (1H,
dd, J¼9.8, 4.4 Hz), 1.58 (3H, s, Me), 1.37 (3H, s, Me), 1.30
(6H, s, 2£Me). 13C NMR: d 143.8, 132.0, 129.0, 127.4,
112.3, 109.6, 104.1, 81.7, 80.6, 75.7, 65.1 (CH2), 52.5, 26.7,
26.5, 26.1. MS: m/z (E1) 352 (27Mþ), 337 (13), 193 (100),
109 (76Mþ2PhS). Anal. calcd for C18H24O5S: C, 61.34; H,
6.86. Found: C, 61.26; H, 7.17.
1
CHCl3). IR (CHCl3): 3475, 3018, 2401, 2358 cm21. H
NMR: d 7.59 (2H, m, aromatic), 7.39 (5H, m, aromatic),
7.24 (3H, t, J¼3.4 Hz, aromatic), 5.60 (1H, s, PHCH), 4.40
(2H, m), 4.02 (5H, m), 3.60 (3H, s, OMe), 3.12 (1H, d,
J¼8.8 Hz, OH). 13C NMR: d 137.4, 135.7, 132.8, 129.1,
128.2, 127.6, 126.4, 103.3, 101.5, 78.6, 70.4, 69.1 (CH2),
65.4, 57.9, 57.3 (OMe). MS: m/z (EI) 374 (6Mþ), 233 (2),
187 (3), 159 (9), 129 (20), 107 (100), 91 (75). Anal. calcd
for C20H22O5S: C, 64.15; H, 5.91. Found: C, 63.98; H, 5.81.
4.4.29. 3-Deoxy-1,2:5,6-di-O-isopropylidene-3-C-phenyl-
sulfide-a-D-glucofuranose 40. Compound 38 (2.35 g,
6.96 mmol) was converted to 40 following a procedure
reported for 35 (1.98 g, 80%). The reaction mixture was
heated at 1258C for 2 h. Eluent: EtOAc:pet ether (4%–
10%). Brown solid. Mp: 75–768C. [a]2D6¼231.3 (c 1.06,
CHCl3). IR (CHCl3): 2889, 2434, 2401, 1944, 1868, 1583,
4.4.25. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsulfonyl-b-D-allopyranoside 36. Compound 35
(0.58 g, 1.54 mmol) was converted to 36 following the
general procedure described above (0.59 g, 95%). Eluent:
EtOAc:pet ether (3:7). Brownish needle shaped solid. Mp:
129–1308C. [a]2D6.5¼246.3 (c 1.00, CHCl3). IR (CHCl3):
1
1481, 1454, 1375 cm21. H NMR: d 7.43 (2H, dd, J¼8.3,
1.5 Hz, aromatic), 7.40–7.19 (3H, m, aromatic), 5.89 (1H,
d, J¼3.4 Hz, H-1), 4.62 (1H, d, J¼3.5 Hz, H-2), 4.45–4.30
(2H, m), 4.16 (1H, dd, J¼8.2, 5.5 Hz), 4.03 (1H, dd, J¼8.8,
4.4 Hz), 3.90 (1H, d, J¼3.4 Hz), 1.52 (3H, s, Me), 1.45 (3H,
s, Me), 1.36 (3H, s, Me), 1.27 (3H, s, Me). 13C NMR: d
134.0, 130.3 129.2, 126.8, 111.9, 109.5, 105.0, 85.4, 80.0,
73.8, 67.7 (CH2), 53.6, 26.9 (Me), 26.7 (Me), 26.3 (Me),
25.3 (Me). MS: m/z (EI) 352 (30Mþ), 337 (29), 193 (58),
164 (25), 101 (100). Anal. calcd for C18H24O5S: C, 61.34;
H, 6.86; S, 9.09. Found: C, 61.66; H, 7.66; S, 9.53.
1
3450, 3427, 3016, 1448 cm21. H NMR: d 7.76 (2H, d,
J¼7.8 Hz, aromatic), 7.23 (8H, a series of m, aromatic),
5.22 (1H, s, PhCH), 5.11 (1H, d, J¼8.3 Hz, H-1), 4.87 (1H,
broad hump), 4.74 (1H, m), 4.35 (1H, q), 4.18 (1H, t,
J¼4.9 Hz), 3.85 (1H, broad hump), 3.68 (1H, q), 3.57 (3H,
s, OMe), 3.54 (1H, m). 13C NMR: d 140.9, 136.1, 133.4,
128.7, 128.5, 128.3, 127.7, 125.9, 101.1 (C-1), 77.1, 76.3,
72.4, 69.3 (CH2), 63.8, 63.2, 56.9 (OMe). MS: m/z (EI) 233
(7), 187 (6), 159 (10), 127 (30), 107 (100), 91 (38), 77 (57).
Anal. calcd for C20H22O7S C, 59.10; H, 5.45; S, 7.88.
Found: C, 58.97; H, 5.66; S, 7.86.
4.4.30. 3-Deoxy-1,2:5,6-di-O-isopropylidene-3-C-phenyl-
sulfonyl-a-D-glucofuranose 41. Compound 40 (0.2 g,
0.565 mmol) was converted to 41 following the general
procedure described above (0.2 g, 94%). Eluent: EtOAc:pet
ether (1:3). Colorless needle shaped solid. Mp: 158–1598C.
[a]2D7¼20.5 (c 1.02, CHCl3). IR (CHCl3): 2358, 2341,
1595, 1585, 1448 cm21. 1H NMR: d 7.96 (2H, d, J¼6.9 Hz,
aromatic), 7.74–7.56 (3H, m, aromatic), 5.96 (1H, d,
J¼3.9 Hz, H-1), 4.96 (1H, d, J¼3.5 Hz, H-2), 4.83–4.73
(1H, m), 4.31 (1H, dd, J¼8.8, 4.8 Hz), 4.18 (1H, dd, J¼8.8,
5.9 Hz), 4.02 (1H, dd, J¼8.8, 4.9 Hz), 3.87 (1H, d,
J¼4.8 Hz), 1.49 (3H, s, Me), 1.35 (3H, s, Me), 1.29 (3H,
s, Me), 1.21 (3H, s, Me). 13C NMR: d 139.6, 134.2, 129.5,
4.4.26. Methyl 2,3-dideoxy-4,6-O-(phenylmethylene)-3-
C-phenylsulfonyl-b-D-erythro-hex-2-enopyranoside 1b.
Compound 36 (0.59 g, 1.472 mmol) was converted to 1b
following the general procedure described above (0.53 g,
93%). The reaction mixture was stirred for 4 h allowing it to
warm up from 08C to room temperature. Eluent: EtOAc:pet
ether (2:3).
4.4.27. Methyl 2-deoxy-4,6-O-(phenylmethylene)-2-C-
phenylsulfide-a-D-altropyranoside 37. Compound 33

A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7213
128.5, 112.4, 109.7, 105.0, 81.3, 80.2, 72.6, 69.9, 68.0
(CH2), 26.7, 26.8, 26.4, 25.2. MS: m/z (EI) 369 (12), 311 (7),
141 (17), 125 (13), 101 (100), 77 (28). Anal. calcd for
C18H24O7S: C, 56.23; H, 6.28; S, 8.34. Found: C, 56.19; H,
6.90; S, 8.62.
4.4.32. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsufonyl-a-D-glucopyranoside 44. Compound 42
(0.13 g, 0.35 mmol) was converted to 44 following the
general procedure described above (0.13 g, 92%). White
needle shaped solid. Mp: 104–1058C. [a]2D7¼þ37.8 (c 0.98,
CHCl3). IR (CHCl3): 3504, 2401, 2360, 23443, 1448,
1
4.4.31. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsulfide-a-D-glucopyranoside 42 and Methyl
3-deoxy-4,6-O-(phenylmethylene)-3-C-phenylsulfide-b-
D-glucopyranoside 43. Acetyl chloride (0.2 mL,
2.451 mmol) was added drop-wise to a well stirred solution
of 40 (0.173 g, 0.491 mmol) in anhydr. MeOH at an ambient
temperature and the mixture was heated under reflux. After
24 h, the reaction mixture was neutralized with BaCO3. The
mixture was concentrated to dryness under reduced pressure
to get a solid mass. The solid was triturated with EtOAc
(30 mL) and the liquid was decanted. The process was
repeated four times. The combined organic layers was
passed through a celite bed. The filtrate was then
concentrated to dryness under reduced pressure to get a
mixture of methyl 3-deoxy-3-C-phenylsulfide-a- and -b-D-
glucopyranosides. To a well stirred solution of the anomers
(0.14 g, 0.491 mmol) in DMF (10 mL) was added a catalytic
amount p-TSA and 1,1-dimethyl toluene (0.15 mL,
0.982 mmol) and the mixture was heated at 1008C with
stirring under reduced pressure. After 1 h, the reaction
mixture was neutralized with pyridine. Excess DMF and
other volatile matters were removed under reduced pressure.
The residue thus obtained was dissolved in saturated
NaHCO3 solution and the aqueous phase was extracted
with EtOAc (4£20 mL). Combined organic layers after
usual work up generated solid material which on purifi-
cation over silica gel using EtOAc:pet ether (1:3) produced
a mixture of 42 and 43 (0.131 g, 71%). Compounds 42 and
43 were finally separated over silica gel using a mixture of
acetone:chloroform:pet ether (7:7:86).
1365 cm21. H NMR: d 7.81 (2H, d, J¼8.3 Hz, aromatic),
7.50 (1H, t, J¼8.0 Hz, aromatic), 7.30 (5H, m, aromatic),
7.10 (2H, d, J¼7.3 Hz, aromatic), 5.44 (1H, s, PhCH), 4.87
(1H, d, J¼3.4 Hz, H-1), 4.50–4.41 (2H, m), 4.23 (1H, dd,
J¼9.3, 3.9 Hz), 3.94–3.69 (4H, m), 3.48 (3H, s, OMe). 13C
NMR: d 140.6, 136.5, 133.9, 129.3, 128.9, 128.8, 128.2,
126.4, 102.0, 98.9, 76.2, 69.4 (CH2), 67.3, 65.9, 62.6, 55.6.
MS: m/z (EI) 406 (,1Mþ), 405 (1), 375 (,1), 233 (20), 187
(12), 159 (14), 127 930), 107 (100), 91 (34), 77 (60). Anal.
calcd for C20H22O7S: C, 59.10; H, 5.45. Found: C, 59.30; H,
5.48.
4.4.33. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsufonyl-b-D-glucopyranoside 45. Compound 43
(0.07 g, 0.181 mmol) was converted to 45 following the
general procedure described above (0.07 g, 90%). Pale
brown solid. Mp: 145–1468C. [a]2D7¼278.6 (c 1.00,
CHCl3). IR (CHCl3): 3502, 2401, 2360, 2331, 1448,
1
1365 cm21. H NMR: d 7.83 (2H, d, J¼6.9 Hz, aromatic),
7.54 (1H, t, J¼7.3 Hz, aromatic), 7.31 (5H, m, aromatic),
7.10 (2H, dd, J¼7.8, 1.9 Hz, aromatic), 5.40 (1H, s, PhCH),
4.45 (1H, d, J¼6.9 Hz, H-1), 4.30 (1H, dd, J¼10.8, 4.8 Hz),
4.18 (1H, dd, J¼9.8, 7.3 Hz), 3.89–3.43 (5H, m), 3.60 (3H,
s, OMe). 13C NMR: d 140.0, 136.5, 134.0, 129.4, 129.1,
128.9, 128.2, 126.3, 104.7, 101.7, 75.8, 69.2, 69.0 (CH2),
68.5, 67.7, 57.6. MS: m/z (EI) 265 (3), 233 (8), 187 (8), 159
(10), 127 (30), 107 (100), 91 (31), 77 (77). Anal. calcd for
C20H22O7S: C, 59.10; H, 5.45. Found: C, 58.88; H, 5.66.
4.4.34. Methyl 3-deoxy-4,6-O-(phenylmethylene)-3-C-
phenylsulfonyl-a-D-glucopyranoside 44 and Methyl 3-
deoxy-4,6-O-(phenylmethylene)-3-C-phenylsulfonyl-b-
D-glucopyranoside 45. Compound 41 (0.21 g, 0.557 mmol)
was converted to an anomeric mixture of 44 and 45 (0.17 g,
75%) following the procedure described for 42 and 43. The
anomers 44 (0.02 g, 11%) and 45 (0.05 g, 28%) were
separated on silica gel. Eluent: acetone:chloroform:pet ether
(1:1:8).
Compound 42 (0.08 g, 44%). Cotton-like white solid. Mp:
129–1308C. [a]2D7¼þ19.2 (c 1.00, CHCl3). IR (CHCl3):
1
3444, 2725, 2360, 2324, 1456, 1373 cm21. H NMR: d
7.57–7.21 (10H, series of m, aromatic), 5.41 (1H, s, PhCH),
4.77 (1H, d, J¼3.5 Hz, H-1), 4.20 (1H, dd, J¼10.2, 4.9 Hz),
3.88–3.81 (1H, m), 3.57 (1H, t, J¼10.3 Hz), 3.50–3.41
(1H, m), 3.41 (3H, s, OMe), 3.28 (1H, t, J¼10.3 Hz), 3.19
(1H, t, J¼10.3 Hz), 2.72 (1H, d, J¼6.3 Hz, OH). 13C NMR:
d 137.3, 135.2, 131.3, 128.9, 128.6, 126.2, 101.6, 99.5, 78.5,
69.7, 69.0 (CH2), 64.4, 55.4 (OMe), 52.4. MS: m/z (EI) 374
(72Mþ), 237 (13), 165 (15), 129 (29), 107 (100), 91 (41), 77
(25). Anal. calcd for C20H22O5S: C, 64.15; H, 5.91. Found:
C, 64.17; H, 6.37.
4.4.35. Methyl 2,3-dideoxy-4,6-O-(phenylmethylene)-3-
C-phenylsulfonyl-a-D-erythro-hex-2-enopyranoside 1a.
To a well stirred solution of 44 (0.09 g, 0.214 mmol) in
pyridine (2 mL) at 08C was added drop-wise mesyl chloride
(0.1 mL, 1.071 mmol) in pyridine (3 mL) and the mixture
was left at þ48C. After 15 h the reaction mixture was
worked up as described in the general procedure. A solution
of the crude material in CH2Cl2 (10 mL) was treated with
DBU (2 equiv.) for 15 min. Excess solvent was removed
under reduced pressure. Purification of the crude residue
over silica gel using EtOAc:pet ether (2:3) furnished 1a as a
solid (0.08 g, 96%).
Compound 43 (0.03 g, 16%). Brown needle shaped solid.
Mp: 84–858C. [a]2D7¼2116.3 (c 0.92, CHCl3). IR (CHCl3):
3502, 2360, 2331, 1471, 1452, 1386, 1365, 1217 cm21. 1H
NMR: d 7.60–7.25 (10H, m, aromatic), 5.45 (1H, s, PhCH),
4.36 (1H, d, J¼7.3 Hz, H-1), 4.31 (1H, dd, J¼10.3, 4.4 Hz),
3.65 (1H, t, J¼10.2 Hz), 3.55 (3H, s, OMe), 3.52–3.40 (1H,
m), 3.34–3.01 (4H, m). 13C NMR: d 137.3, 135.6, 130.6,
129.2, 128.8, 128.4, 126.2, 105.4, 101.6, 77.9, 71.2, 69.5,
68.8 (CH2), 57.4, 54.5. MS: m/z (EI) 374 (65Mþ), 187 (13),
159 (11), 129 (21), 107 (100), 91 (84), 77 (52). Anal. calcd
for C20H22O5S: C, 64.15; H, 5.91; S, 8.56. Found: C, 64.33;
H, 5.81; S, 8.95.
4.4.36. Methyl 2,3-dideoxy-4,6-O-(phenylmethylene)-3-
C-phenylsulfonyl-b-D-erythro-hex-2-enopyranoside 1b.
Compound 45 (0.05 g, 0.120 mmol) was converted to
1b following the procedure described for 1a (0.045 g,
96%).

7214
A. K. Sanki, T. Pathak / Tetrahedron 59 (2003) 7203–7214
7. Welch, C. J.; Bazin, H.; Chattopadhyaya, J. Acta Chem. Scand.
Acknowledgements
1986, B40, 343–357.
8. Baker, B. R.; Schaub, R. E.; Williams, J. H. J. Am. Chem. Soc.
1955, 77, 7–12.
This work has been supported by a research grant from the
Department of Science and Technology, New Delhi, India.
AKS thanks the Council of Scientific and Industrial
Research, New Delhi, India for a fellowship.
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