A simple and convenient synthetic protocol for O-isopropylidenation of sugars using bromodimethylsulfonium bromide (BDMS) as a catalyst

Article abstract of DOI:10.1016/j.carres.2009.09.017

Various O-isopropylidene derivatives of sugars and acyclic sugars were obtained in very good yields on reaction with acetone at room temperature with a catalytic amount of bromodimethylsulfonium bromide (BDMS). These O-isopropylidene derivatives can also be prepared in good yields on reaction with 2,2-dimethoxypropane (DMP) in acetonitrile using the same catalyst in shorter reaction times. Some of the advantages of this method are high effectiveness, a nonaqueous workup procedure, economic viability, and good yields.

Full text of DOI:10.1016/j.carres.2009.09.017

Carbohydrate Research 345 (2010) 154–159
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Note
A simple and convenient synthetic protocol for O-isopropylidenation
of sugars using bromodimethylsulfonium bromide (BDMS) as a catalyst
*
Abu T. Khan , Md. Musawwer Khan
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 791 039, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 12 July 2009
Received in revised form 11 September 2009
Accepted 15 September 2009
Available online 19 September 2009
Various O-isopropylidene derivatives of sugars and acyclic sugars were obtained in very good yields on
reaction with acetone at room temperature with a catalytic amount of bromodimethylsulfonium bromide
(BDMS). These O-isopropylidene derivatives can also be prepared in good yields on reaction with 2,2-
dimethoxypropane (DMP) in acetonitrile using the same catalyst in shorter reaction times. Some of the
advantages of this method are high effectiveness, a nonaqueous workup procedure, economic viability,
and good yields.
Keywords:
Acetals
Ó 2009 Elsevier Ltd. All rights reserved.
Carbohydrates
Bromodimethylsulfonium bromides
O-Isopropylidenation
Acetonation
The O-isopropylidene derivatives of sugars,1 which are also
known as acetonides of aldoses and ketoses, have been used exten-
sively in carbohydrate chemistry to selectively protect the hydro-
xyl groups of different sugars.2 They serve as valuable building
blocks in carbohydrate chemistry, such as glycosyl acceptors3
and glycosyl donors.4 In addition, many of them have been used
as key starting materials for natural product synthesis.5,6 For
(MP) in the presence of a trace amount of acid catalyst.13 Over
the years, a wide variety of catalysts have been explored for the
synthesis of O-isopropylidene derivative of sugars such as iodine,14
and many Lewis acidic metal salts namely CuSO4,15 FeCl3,16 AlCl3,17
and ceric ammonium nitrate (CAN).18 In addition, various hetero-
geneous catalysts have also been employed, such as Zeolite HY,19
montmorillonite clay,20 triphenylphosphine polymer-bound/io-
dine complex,21 and sulfuric acid immobilized on silica gel22 as
well as vanadyl triflate (VO(OTf)2ꢀxH2O).23 However, some of these
methods have certain drawbacks such as low yields, harsh,19,22 and
inert atmospheric reaction conditions.21,23 Hence, there is a need to
devise a simple and practical synthetic methodology for the prep-
aration of these valuable derivatives on a large scale.
The synthetic utility of bromodimethylsulfonium bromide (BDMS)
has been explored by us24,25 as well as by others26–28 as a brominat-
ing reagent as well as an efficient catalyst in various organic trans-
formations. Recently, Ye and co-workers have demonstrated the
usefulness of BDMS as a promoter for glycosylation reactions.29 Very
recently its application in various organic transformations has also
been reviewed by us.30 Earlier we have reported the preparation of
O,O-acetals of various carbonyl compounds with 1,2-ethanediol
or 1,3-propanediol using bromodimethylsulfonium bromide (BDMS).31
However, the acetalization reaction with carbohydrate molecules
was not studied by using BDMS as a catalyst. As part of our ongoing
research project to develop a new synthetic methodology, we wish
to report here a practical and efficient method for the synthesis of
O-isopropylidenation of sugars at room temperature with bro-
modimethylsulfonium bromide (BDMS) as a new catalyst for these
processes (Scheme 1).
example, 1,2:3,4:5,6-tri-O-isopropylidene-
been used in the total synthesis of (+)-7-epi-goniofufurone7 and
other analogues. Similarly, 2,3:4,5-di-O-isopropylidene- -xylose
D-mannitol (15) has
D
diethyl dithioacetal (22) has been utilized for the total synthesis
of (+)-phorboxazole A, a potent cytostatic agent.8 Moreover, these
sugar derivatives are also important materials for structural and
conformational studies.9 Interestingly, some of them also exhibit
important pharmacological properties. For example, 1,2:5,6-di-O-
isopropylidene-a-D-glucofuranose (12) is well known for its anti-
inflammatory and antipyretic activities with a very low toxicity.10
Therefore, there is a continued research interest to prepare these
compounds in significant quantities.
The O-isopropylidenation of a carbohydrate molecule is usually
performed by using anhydrous acetone in the presence of an acid
catalyst such as concentrated H2SO4 or anhydrous ZnCl2.11 In addi-
tion, the same transformations are also possible by employing
other acetonide-forming agents such as 2,2-dimethoxypropane
(DMP) in N,N-dimethylformamide (DMF)12 or 2-methoxypropene
* Corresponding author. Tel.: +91 361 2582305; fax: +91 361 2582349.
E-mail address: atk@iitg.ernet.in (A.T. Khan).
0008-6215/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved.
doi:10.1016/j.carres.2009.09.017

A. T. Khan, Md. Musawwer Khan / Carbohydrate Research 345 (2010) 154–159
155
mercially available
was stirred in the presence of 5 mol % of the catalyst, and the product
isolatedfromthereactionwas1,2:5,6-di-O-isopropylidene- -glu-
D-glucose (1, 2 mmol) in 10 mL of dry acetone
O
HO
HO
BDMS (5 mol%)
O
O
OH
OH
O
a-D
dry acetone or DMP
rt
cofuranose (12) in 84% yield. The product was characterized by its
melting point, 1H NMR, 13C NMR spectra and specific rotation as well
as by its elemental analysis. The spectral data were also compared
with the earlier reported data.21 Then the same reaction was carried
out with 2,2-dimethoxypropane (DMP) in acetonitrile by employing
the same amount of catalyst at room temperature. In this case we
also obtained product 12 in 90% yield. The important feature of this
modified reaction is that it took relatively much less reaction time as
compared to that using dry acetone alone, which is shown in Table 1.
From the outcome of the reactions, we conclude that only the ther-
modynamically controlled product was formed. Next, we have stud-
yields 83-95%
Scheme 1. O-Isopropylidenation of sugars.
For our requirements, bromodimethylsulfonium bromide (BDMS)
was prepared by following the literature procedure.24 At the outset,
we have tried to optimize the reaction conditions to obtain the de-
sired O-isopropylidene derivatives. Using D-glucose (1) as a model
substrate, after several trial reactions it was found that employing
5 mol % of BDMS provided the best results. Then a mixture of com-
Table 1
Preparation of O-isopropylidene derivatives of sugars using bromodimethylsulfonium bromide (BDMS)
Entry
Substrate
Product
Time (h)
Method
Yielda,b (%)
O
OH
O
O
O
HO
HO
O
1
10
4
A
B
84
90
OH
OH
O
HO
1
12
O
OH
OH
HO
OH
O
O
O
2
10
4
A
B
85
91
O
OH
OH
O
13
2
O
O
O
HO
OH
HO
HO
HO
O
3
2
1
A
B
90
95
O
O
OH
3
14
OH OH
O
O
OH
O
HO
O
4
3
1
A
B
86
89
OH OH
O
O
4
15
O
OH
O
O
O
5
10
A
86
HO
O
OH
OH
O
16
5
O
O
O
HO
O
HO
6
2
A
91
OH
OH
O
O
6
17
(continued on next page)

156
A. T. Khan, Md. Musawwer Khan / Carbohydrate Research 345 (2010) 154–159
Table 1 (continued)
Entry
Substrate
Product
Time (h)
Method
Yielda,b (%)
HO
OH
O
O
O
HO
OH
OH
7
2
A
86
OH
OH
O
7
18
O
OH
O
HO
HO
8
2
A
88
O
O
HO
OH
8
19
O
SEt
SEt
OH
OH SEt
OH
SEt
9
10
11
2
2
2
A
A
A
89
86
83
OH OH
O
OH
9
20
O
SEt
SEt
OH SEt
O
HO
HO
SEt
O
O
OH OH
10
21
O
SEt
SEt
OH SEt
O
SEt
O
O
OH OH
11
22
Method A: sugar (2 mmol) in dry acetone (10 mL) using BDMS (22 mg, 0.1 mmol).
Method B: sugar (2 mmol) in dry acetonitrile (10 mL) and 2,2-dimethoxypropane (1.0 mL, 8.14 mmol) using BDMS (22 mg, 0.1 mmol.)
a
Isolated yield.
b
All products were characterized by 1H and 13C NMR spectroscopy, optical rotation, and elemental analysis.
iedthe reactionsof
same mol % of the catalyst under identical reaction conditions. In
boththecases, weobtainedthethermodynamicallycontrolledprod-
uct, 1,2:3,4-di-O-isopropylidene-
85% and 91%, respectively. By encouraging results,
was kept for isopropylidenation with acetone as well as with DMP
individually under similar reaction conditions. The product was
2,3:5,6-di-O-isopropylidene-
both the reactions in good yields. The literature reveals32 that the
isopropylidenation of -mannose (3) usually provides the thermo-
D
-galactose(2) with acetoneas well asDMP using
pylidene-
product 14a, which is shown in Figure 1.
Likewise, -mannitol (4) was converted into the corresponding
1,2:3,4:5,6-tri-O-isopropylidene- -mannitol (15) in very good
yields as shown in Table 1. Similarly, various sugars such as -arab-
inose (5), -xylose (6), -ribose (7), and -rhamnose (8) were con-
verted to the corresponding O-isopropylidene derivatives 16–19
in good yields using dry acetone in the presence of 5 mol % of
BDMS.
D-mannofuranose (14) instead of kinetically controlled
D
D
-galactopyranose(13) in a yieldof
-mannose (3)
D
D
L
D
D
L
D-mannofuranose (14) formed from
D
To show the generality of our protocol, a series of diethyl dithio-
dynamically controlled product 14 preferably on reaction with ace-
tone or DMP in the presence of an acid catalyst instead of 14a as
shown in Scheme 2. However, recently, Rajput and Mukhopadhyay
wrongly reported22 the formation of 2,3:4,6-di-O-isopropylidene-
acetal of sugars such as L-rhamnose (9), L-arabinose (10), and D-xy-
lose (11) were further examined using identical conditions. The
products 20, 21, and 22 were obtained in good yields from the cor-
responding dithioacetal derivatives. The results are summarized in
Table 1. All these products were characterized by 1H and 13C NMR
spectroscopy, as well as by elemental analysis. Interestingly, the
diethyl dithioacetal group remains unaffected under these experi-
mental conditions. Notably, we have also verified that the
conversion of the various free sugars to the corresponding O-iso-
propylidene derivatives can be carried out in an even larger scale
(100 mmol) without any difficulty by using 3 mol % of the catalyst
D-mannopyranose (14a), a kinetically controlled product, using dry
acetone in the presence of silica gel-supported sulfuric acid,
although the spectral data closely matched with those of our
compound.
To resolve the ambiguity of the structure, we have collected sin-
gle crystal X-ray diffraction data of the product, and it was found
that the structure of the product was that of 2,3:4,5-di-O-isopro-

A. T. Khan, Md. Musawwer Khan / Carbohydrate Research 345 (2010) 154–159
157
O
O
HO
O
O
HO
HO
O
OH
O
O
O
2-methoxypropene
H+
acetone or DMP
H+
O
HO
OH
OH
O
O
3
Kinetically Controlled
Thermodynamically Controlled
14a
14
Scheme 2. Rationalization of acetonation product from D-mannose.
tions, not only provided a low yield (70%) of product, but also re-
quired much longer reaction time (5 h).
In summary, we have developed a simple, efficient, and cata-
lytic method for the preparation of O-isopropylidene derivatives
from free sugars as well as from other sugar derivatives by employ-
ing bromodimethylsulfonium bromide as a new catalyst for these
processes. The notable advantages of the present protocol are good
yields, clean reactions, and shorter reaction time. The reaction
products can be obtained by direct recrystallization in case of solid
products without going through tedious chromatographic separa-
tions. These processes involve nonaqueous workup procedures.
Due to its operational simplicity, generality, and efficacy, this
method is expected to have much wider applicability for the prep-
aration of O-isopropylidene sugar derivatives on a large scale in the
future.
Figure 1. ORTEP plot of 2,3:5,6-di-O-isopropylidene-D-mannofuranose (3b) with
atom numbering scheme.
1. Experimental
instead of the heretofore required 5 mol %. For instance, when a
mixture of -mannitol (4) (18.22 g, 100 mmol) and dry acetone
1.1. General methods
D
(400 mL) was treated with bromodimethylsulfonium bromide
(0.670 g, 3 mmol), it was smoothly converted within 3 h to the
O-isopropylidene derivative 15 in 92% yield. The following workup
procedure was followed for the large-scale reaction. After complet-
ing the reaction, the reaction mixture was neutralized with solid
NaHCO3, and then it was passed through a Celite pad. Acetone
was removed on a rotary evaporator, and the crude solid residue
was recrystallized from ethanol to obtain the pure product. A total
of 27.82 g of the pure product 15 was obtained from the above
reaction. In this reaction, we have obtained a much better yield,
and the reaction time is shorter than that with concentrated
H2SO4.7
Starting material and reagents were purchased from commer-
cial suppliers. Concentration under reduced pressure refers to the
use of a rotary evaporator. Residual solvent was removed under
high vacuum pressure. Analytical thin-layer chromatography was
performed on precoated TLC plates (0.2 mm layer thickness of Sil-
ica Gel 60 F-254). Spots were visualized by staining with iodine va-
por or MOSTAIN solution (by dissolving 20 g ammonium
heptamolybdate and 0.4 g cerium(IV) sulfate in 400 mL of 10%
H2SO4 solution). Column chromatography was carried out using
silica gel (60–120 mesh, E. Merck or Qualigen). Melting points
were determined on a Büchi melting point apparatus and are
uncorrected. Optical rotations were measured with a Perkin–Elmer
243 polarimeter at 25 °C. IR spectra were recorded on a Perkin–El-
mer Spectrum One FTIR spectrometer. 1H and 13C NMR spectra
were recorded on a Varian (400 MHz) spectrometer using TMS as
internal reference. Chemical shifts are reported in parts per million
(ppm) down field from TMS on the d scale. 1H NMR data are re-
ported in the order of chemical shift, multiplicity (s = singlet,
d = doublet, t = triplet, dd = doublet of doublet, and m = multiplet),
number of protons, and coupling constant in hertz (Hz). Elemental
analyses were performed by Perkin–Elmer CHNS/O-2400 analyzer.
The formation of the O-isopropylidene products can be rational-
ized as follows: It has been proposed that bromodimethylsulfoni-
um bromide may generate dry HBr in the medium upon reaction
with the sugars. We believe that in situ-generated dry HBr cata-
lyzes the O-isopropylidenation reaction of sugars or sugar deriva-
tives into the corresponding O-isopropylidene derivatives
(Scheme 3). It is also noted that the pH of the solution is ꢁ2–3 dur-
ing the reaction. The reaction of D-mannitol (4) and dry acetone
was also examined with an equivalent amount of 48% aqueous
HBr at room temperature. It was observed that under these condi-
Sugar
Sugar
HBr
Me2S Br Br
OH
OH
O
OH
S Me2 Br
Sugar
Sugar
(CH3)2CO
O
OH OH
O
Scheme 3. Proposed mechanism for O-isopropylidenation of carbohydrates using BDMS.

158
A. T. Khan, Md. Musawwer Khan / Carbohydrate Research 345 (2010) 154–159
The X-ray diffraction data were collected on a Bruker Apex II smart
diffractometer at 293 K.
(s, 6H, 2 ꢄ CH3), 1.31 (d, 3H, J = 5.6 Hz, CH3), 1.30 (t, 3H,
J = 7.6 Hz, SCH2CH3), 1.29 (t, 3H, J = 7.2 Hz, SCH2CH3); 13C NMR
(100 MHz, CDCl3): d 109.2, 84.5, 80.0, 75.6, 69.3, 54.8, 27.0 (2C),
26.2, 25.9, 20.3, 14.9, 14.6. Anal. Calcd for C13H26O4S2 (312.5): C,
50.29; H, 8.44; S, 20.65. Found: C, 50.18; H, 8.36; S, 20.46.
Compounds 12–14, 16, and 18 have been reported previously,21
and the spectral data are in good agreement with our data.
1.2. General procedures for the O-isopropylidenation
1.2.7. 2,3:4,5-Di-O-isopropylidene-L-arabinose diethyl
1.2.1. Method A: using anhydrous acetone
dithioacetal (21)
Bromodimethylsulfonium bromide (BDMS) (22 mg, 0.10 mmol)
was added to a stirred solution of sugar (2 mmol) in dry acetone
(10 mL) at room temperature. The reaction time was monitored
by TLC as mentioned in Table 1. After completion of the reaction,
the reaction mixture was concentrated in rotary evaporator. The
crude residue was recrystallized in ethanol to obtain the desired
product. However, in case of a liquid product or low-melting solid
product, the crude residue was passed through a silica gel column
to obtain the pure product.
Oil; ½a 2D5
ꢂ
ꢃ80.8 (c 1.0, MeOH) [lit34
½
a 2D5
ꢂ
ꢃ81 (c 1.0, MeOH)]; IR
1H NMR
(KBr): 2986, 2931, 1455, 1372, 1219, 1064, 847 cmꢃ1
;
(400 MHz, CDCl3): d 4.28–4.32 (m, 1H), 4.12–4.16 (m, 3H), 4.04
(d, 1H, J = 2.8 Hz, H-1), 3.97 (dd, 1H, J = 4.4, 8.4 Hz), 2.60–2.80 (m,
4H, 2 ꢄ SCH2CH3), 1.45 (s, 3H, CH3), 1.42 (s, 3H, CH3), 1.38 (s, 3H,
CH3), 1.34 (s, 3H, CH3), 1.28 (t, 3H, J = 7.6 Hz, SCH2CH3), 1.26 (t,
3H, J = 7.6 Hz, SCH2CH3); 13C NMR (100 MHz, CDCl3): d 110.2,
109.8, 84.6, 79.2, 77.2, 67.8, 52.4, 27.4, 27.2, 26.8, 25.3, 25.2,
25.0, 14.5, 14.4. Anal. Calcd for C15H28O4S2 (336.5): C, 53.54; H,
8.39; S, 19.06. Found: C, 53.41; H, 8.29; S, 18.88.
1.2.2. Method B: using 2,2-dimethoxypropane
Into a mixture of sugar (2 mmol) in dry acetonitrile (10 mL) and
2,2-dimethoxypropane (1.0 mL, 8.14 mmol) was added bro-
modimethylsulfonium bromide (BDMS) (22 mg, 0.1 mmol) at room
temperature. After completion of the reaction as indicated by TLC,
the reaction mixture was concentrated on a rotary evaporator. A
similar procedure to that above (Section 1.2.1) was used to obtain
the desired product in pure form.
1.2.8. 2,3:4,5-Di-O-isopropylidene-D-xylose diethyl dithioacetal
(22)
Oil; ½a 2D5
ꢂ
ꢃ68.6 (c 2.0, Me2CO) [lit8 ½a D25
ꢂ
ꢃ70.1 (c 2.6, Me2CO)]; IR
1H NMR
(KBr): 2981, 2935, 1453, 1370, 1229, 1063, 841 cmꢃ1
;
(400 MHz, CDCl3): d 4.32–4.36 (m, 2H), 4.15 (dd, 1H, J = 3.2,
7.2 Hz), 4.06 (dd, 1H, J = 6.8, 8.0 Hz), 3.94 (t, 1H, J = 7.6 Hz), 3.91
(d, 1H, J = 5.6 Hz), 2.69–2.81 (m, 4H, 2 ꢄ SCH2CH3), 1.47 (s, 3H,
CH3), 1.44 (s, 6H, CH3), 1.38 (s, 3H, CH3), 1.28 (t, 3H, J = 7.6 Hz,
SCH2CH3), 1.27 (t, 3H, J = 7.6 Hz, SCH2CH3); 13C (100 MHz, CDCl3):
d 110.3, 109.8, 80.3, 78.9, 75.5, 66.1, 53.3, 27.6, 27.4, 26.4, 25.8,
25.6, 25.2, 14.6, 14.5. Anal. Calcd for C15H28O4S2 (336.5): C,
53.54; H, 8.39; S, 19.06. Found: C, 53.28; H, 8.32; S, 19.22.
1.2.3. 1,2:3,4:5,6-Tri-O-isopropylidene-D-mannitol (15)
White solid; mp 70–71 °C (lit7 68–70 °C); ½a D25
ꢂ
+13.4 (c 1.0,
;
MeOH); IR (KBr): 2983, 1371, 1256, 1064, 749 cmꢃ1
1H NMR
(400 MHz, CDCl3): d 4.18–4.22 (m, 2H), 4.08 (dd, 2H, J = 6.4,
8.4 Hz), 3.99 (dd, 2H, J = 6.0, 8.4 Hz), 3.95 (dd, 2H, J = 2.0, 4.8 Hz),
1.43 (s, 6H, 2 ꢄ CH3), 1.40 (s, 6H, 2 ꢄ CH3), 1.36 (s, 6H, 2 ꢄ CH3);
13C NMR (100 MHz, CDCl3): d 110.4, 109.8, 79.6, 76.5, 66.5, 27.7,
26.7, 25.5. Anal. Calcd for C15H26O6 (302.4): C, 59.58; H, 8.67.
Found: C, 59.44; H, 8.58.
1.2.9. X-ray crystallographic data
2:3;5:6-Di-O-isopropylidene-D-mannofuranose (14): empirical
formula C12H20O6, colorless prismatic crystal, formula wt 260.28,
orthorhombic, P2(1), a = 6.6693(9), b = 10.8368(18), c = 18.904(3) Å,
V = 1366.3(4) Å3, Z = 4,
l
(k Mo K
(0 0 0) = 560, GOF(S) = 0.986. Final indices R1 = 0.0418, wR2 =
0.0899 with I > 2 (I); R1 = 0.0857, wR2 = 0.1060 for all data.
a
0.71073 Å) = 0.101 mmꢃ1. F
1.2.4. 1,2:3,5-Di-O-isopropylidene-D-xylofuranose (17)
White solid; mp 42–44 °C (lit14 44–46 °C); ½a D25
ꢂ
+12.2 (c 1.5,
r
H2O) [lit14
½
a 2D5
+12.8 (c 2.6, H2O)]; IR (KBr): 2990, 2938, 1375,
ꢂ
1200, 1165, 1081, 824 cmꢃ1 1H NMR (400 MHz, CDCl3): d 6.01
;
Acknowledgments
(d, 1H, J = 4.0 Hz, H-1), 4.53 (d, 1H, J = 4.0 Hz), 4.30 (d, 1H,
J = 2.4 Hz), 4.08–4.10 (m, 2H), 4.03–4.04 (m, 1H), 1.50 (s, 3H,
CH3), 1.45 (s, 3H, CH3), 1.39 (s, 3H, CH3), 1.33 (s, 3H, CH3); 13C
NMR (100 MHz, CDCl3): d 111.8, 105.3, 97.6, 84.8, 73.3, 71.7,
60.3, 29.0, 26.9, 26.3, 18.8. Anal. Calcd for C11H18O5 (230.3): C,
57.38; H, 7.88. Found: C, 57.22; H, 7.78.
MMK is thankful to UGC, New Delhi, India for a research fellow-
ship. We acknowledge DST, New Delhi for providing the single
crystal XRD facility to the Department of Chemistry under FIST Pro-
gramme (S. No.: SR/FST/CSII-007/2003). We are grateful to the
Director, IIT Guwahati, for providing the general facilities to carry
out this work.
1.2.5. 2,3-O-Isopropylidene-
L
-rhamnofuranose (19)
+16.2 (c 2.0, water) [lit33
+17.6 (c 2.8, H2O)]; IR
1H NMR
Oil; ½a 2D5
ꢂ
½ ꢂ
a 2D5
Supplementary data
(Neat): 3434, 2923, 1489, 1071, 1021, 825 cmꢃ1
;
(400 MHz, CDCl3): d 5.40 (d, 1H, J = 1.6 Hz, H-1), 4.87 (dd, 1H,
J = 3.6, 6.0 Hz), 4.60 (d, 1H, J = 6.0 Hz), 4.05–4.00 (m, 1H), 3.93
(dd, 1H, J = 3.6, 7.2 Hz), 2.80 (br s, 1H, OH), 2.61 (d, 1H, J = 6.0 Hz,
OH), 1.46 (s, 3H, CH3), 1.32 (d, 3H, J = 6.0 Hz, CH3), 1.31 (s, 3H,
CH3); 13C NMR (100 MHz, CDCl3): d 112.9, 101.1, 85.6, 83.6, 80.3,
66.8, 26.1, 24.7, 20.6. Anal. Calcd for C9H16O5 (204.22): C, 52.93;
H, 7.90. Found: C, 52.81; H, 7.79.
Complete crystallographic data of 14 for the structural analysis
have been deposited with the Cambridge Crystallographic Data
Centre, CCDC No. 685637. Copies of this information may be ob-
tained free of charge from the Director, Cambridge Crystallographic
Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK, (fax: +44-
1223-336033, e-mail: deposit@ccdc.cam.ac.uk or via: www.ccdc.
cam.ac.uk). Supplementary data (CIF file, 1H NMR, 13C NMR) asso-
ciated with this article can be found, in the online version, at
doi:10.1016/j.carres.2009.09.017.
1.2.6. 2,3-O-Isopropylidene-L-rhamnose diethyl dithioacetal
(20)
Oil; ½a 2D5
ꢂ
ꢃ30 (c 2.0, CHCl3); IR (KBr): 3350, 2972, 2929, 1453,
1H NMR (400 MHz, CDCl3): d 4.19
References
1373, 1259, 1071, 873 cmꢃ1
;
(d, 1H, J = 2.0 Hz, H-1), 4.07 (dd, 1H, J = 7.2, 8.8 Hz, H-3), 3.84 (dd,
1H, J = 2.0, 8.8 Hz, H-2), 3.79 (dd, 1H, J = 6.4, 7.6 Hz), 3.71 (t, 1H,
J = 7.6 Hz), 2.66–2.76 (m, 4H, 2 ꢄ SCH2CH3), 2.09 (s, 1H, OH), 1.38
1. Greene, T. W.; Wuts, P. G. M. Protecting Groups in Organic Synthesis, 4th ed.;
Wiley & Sons: New York, 2007; pp 306–318.
2. Clode, D. M. Chem. Rev. 1979, 79, 491–513.

A. T. Khan, Md. Musawwer Khan / Carbohydrate Research 345 (2010) 154–159
159
3. Yamanoi, T.; Oda, Y.; Matsuda, S.; Yamazaki, I.; Matsumura, K.; Katsuraya, K.;
Watanabe, M.; Inazu, T. Tetrahedron 2006, 62, 10383–10392.
4. Veeneman, G. H. In Carbohydrate Chemistry; Boons, G.-J., Ed.; Blackie Academic
& Professional: London, 1998; pp 141–142.
19. Rauter, A. P.; Ramôa-Ribeiro, F.; Fernandes, A. C.; Figueiredo, J. A. Tetrahedron
1995, 51, 6529–6540.
20. Asakura, J.-I.; Matsubara, Y.; Yoshihara, M. J. Carbohydr. Chem. 1996, 15, 231–
239.
5. Alam, M. A.; Vankar, Y. D. Tetrahedron Lett. 2008, 49, 5534–5536.
6. Garegg, P. J. In Preparative Carbohydrate Chemistry; Hanessian, S., Ed.; Marcel
Dekker: New York, 1997; pp 3–33.
7. Yadav, V. K.; Agrawal, D. Chem. Commun. (Cambridge) 2007, 48, 5232–5234.
8. Pattenden, G.; González, M. A.; Little, P. B.; Millan, D. S.; Plowright, A. T.;
Tornos, J. A.; Ye, T. Org. Biomol. Chem. 2003, 1, 4173–4208.
9. Roslund, M. U.; Klika, K. D.; Lehtila, R. L.; Taehtinen, P.; Sillanpaeae, R.; Leino, R.
J. Org. Chem. 2004, 69, 18–25.
10. Goi, A.; Bruzzese, T.; Notarianni, A. F.; Riva, M.; Ronchini, A. Arzneim.-Forsch./
Drug Res. 1979, 29, 986–990.
11. Schmidt, O. Th. Methods Carbohydr. Chem. 1963, 2, 318–320.
12. Kitamura, M.; Isobe, M.; Ichikawa, Y.; Goto, T. J. Am. Chem. Soc. 1984, 106,
3252–3257.
21. Silvana, P.; Annalisa, G.; Daniele, D.; Mauro, D. N.; Giovanni, P. Synthesis 2006,
305–308.
22. Rajput, V. K.; Mukhopadhyay, B. Tetrahedron Lett. 2006, 47, 5939–5941.
23. Lin, C.-C.; Jan, M.-D.; Weng, S.-S.; Lin, C.-C.; Chen, C.-T. Carbohydr. Res. 2006,
341, 1948–1953.
24. Khan, A. T.; Ali, M. A.; Goswami, P.; Choudhury, L. H. J. Org. Chem. 2006, 71,
8961–8963.
25. Khan, A. T.; Parvin, T.; Choudhury, L. H. J. Org. Chem. 2008, 73, 8398–8402. and
references cited therein.
26. Jiang, B.; Dou, Y.; Xu, X.; Xu, M. Org. Lett. 2008, 10, 593–596.
27. Bhalerao, D. S.; Akamanchi, K. G. Synlett 2007, 2952–2956.
28. Das, B.; Srinivas, Y.; Holla, H.; Laxminarayana, K.; Narender, R. Tetrahedron Lett.
2007, 48, 6681–6683.
13. Gelas, J.; Horton, D. Heterocycles 1981, 16, 1587–1601.
14. Kartha, K. P. R. Tetrahedron Lett. 1986, 27, 3415–3416.
15. Hering, K. W.; Karaveg, K.; Moremen, K. W.; Pearson, W. H. J. Org. Chem. 2005,
70, 9892–9904.
29. Xiong, D.-C.; Zhang, L.-H.; Ye, X.-S. Adv. Synth. Catal. 2008, 350, 1696–1700.
30. Khan, A. T.; Parvin, T.; Choudhury, L. H. Tetrahedron 2009, 65, 9513–9526.
31. Khan, A. T.; Mondal, E.; Ghosh, S.; Islam, S. Eur. J. Org. Chem. 2004, 2002–
2009.
16. Singh, P. P.; Gharia, M. M.; Dasgupta, F.; Srivastava, H. C. Tetrahedron Lett. 1977,
5, 439–440.
32. Stick, R. V. Carbohydrates: The Sweet Molecules of Life, Academic Press: New
York, 2001; pp 55–56.
17. Lal, B.; Gidwani, R. M.; Rupp, R. H. Synthesis 1989, 711–713.
18. Manzo, E.; Barone, G.; Parrilli, M. Synlett 2000, 887–889.
33. Haines, A. H. Carbohydr. Res. 1965, 1, 214–228.
34. Horton, D.; Varela, O. Carbohydr. Res. 1984, 134, 205–214.