Ferrier rearrangement catalyzed by HClO4-SiO2: Synthesis of 2,3-unsaturated glycopyranosides

Article abstract of DOI:10.1055/s-2004-837297

Alkyl 2,3-unsaturated glycopyranosides have been prepared by the Ferrier rearrangement of acetyl protected glycals catalyzed by HClO₄-SiO ₂. Operational simplicity, use of economically convenient catalyst, mild reaction conditions, high yields, short reaction times are the key features of this protocol.

Full text of DOI:10.1055/s-2004-837297

260
PAPER
Ferrier Rearrangement Catalyzed by HClO4–SiO2: Synthesis of
2,3-Unsaturated Glycopyranosides1
S
ynthesis of 2,3-U
n
nsaturated G
u
lycopyranosi
p
des Kumar Misra,* Pallavi Tiwari, Geetanjali Agnihotri
Medicinal and Process Chemistry Division, Central Drug Research Institute, Chattar Manzil Palace, Lucknow 226001, UP, India
Fax +91(522)2223938, +91(522)2223405; E-mail: akmisra69@rediffmail.com
Received 19 May 2004; revised 6 September 2004
As a part of our current interest in the development of en-
vironmental-friendly catalytic processes, we set out to ex-
plore the catalytic potential of HClO4/SiO2,18 an
inexpensive catalyst in the Ferrier rearrangement to pre-
pare 2,3-unsaturated O-glycosides and we are pleased to
report herein the HClO4/SiO2 catalyzed allylic rearrange-
ment of acetoxy glycals with alcohols leading to the for-
mation of 2,3-unsaturated O-glycosides. The reaction
proceeded smoothly at room temperature and the products
were obtained in excellent yields. A variety of functional
groups such as allyl, propargyl, isopropylidene, benzyl,
isopropyl groups are compatible under the reaction condi-
tions and no formation of by-products was observed. Af-
ter successful application of the catalyst in the formation
of 2,3-unsaturated O-glycosides, thiols have been used in-
stead of alcohols to give 2,3-unsaturated thioglycosides
and most gratifyingly 2,3-unsaturated thioglycosides
were formed cleanly without the formation of any by-
products as reported earlier in the case of Ferrier rear-
rangement using thiols. The generality of the reaction
conditions has been extended towards the formation of
several important disaccharides by using hydroxy sugars
as a substitute for simple alcohols.
Abstract: Alkyl 2,3-unsaturated glycopyranosides have been pre-
pared by the Ferrier rearrangement of acetyl protected glycals cata-
lyzed by HClO4–SiO2. Operational simplicity, use of economically
convenient catalyst, mild reaction conditions, high yields, short re-
action times are the key features of this protocol.
Key words: carbohydrates, glycosides, glycosylations, rearrange-
ments, synthesis
2,3-Unsaturated glycosides or pseudoglycals obtained by
Ferrier rearrangement represent versatile chiral intermedi-
ates towards the synthesis of modified carbohydrates and
nucleosides with important pharmacological properties.2
This class of compounds can be transformed into 2-deoxy
or 2,3-dideoxy sugars which are building blocks for the
total synthesis of many antibiotics.3 2,3-Unsaturated gly-
cosides are generally prepared by strong Lewis acid cata-
lyzed allylic rearrangement of acyloxy glycals.4 Due to its
great significance in the area of carbohydrate chemistry,
there has been a growing interest in the improvement of
the Ferrier reaction by using a variety of catalysts. Recent
literature reports describe the formation of 2,3-unsaturat-
ed O-glycosides by using strong Lewis acids such as bo-
ron trifluoride diethyl etherate5 or stannic chloride.6 Other
reagents which have been used for this transformation un-
der different conditions are iodine,7 montmorillonite K
10,8 DDQ,9 N-iodosuccinimide,10 lithium tetrafluorobo-
rate,11 indium chloride,12 indium bromide,13 scandium tri-
flate,14 ytterbium triflate,15 bismuth chloride16 and ferric
chloride.17 Despite their usefulness, many of the above-
mentioned methods suffer from disadvantages, such as,
strong acidity as in the cases of BF3·OEt2, SnCl4 and
montmorillonite K 10, strong oxidizing conditions as in
the case of DDQ, longer reaction times, unsatisfactory
yields, low stereoselectivity and use of an excess of re-
agent or catalysts as in the cases of BF3·OEt2 and NIS. For
instance, in the case of BF3·OEt2 catalyzed reaction, it re-
quires the addition of a varied quantity of catalyst. Fur-
thermore, the metal triflates that have been used for these
transformations are highly expensive. Therefore, there is
a constant need for a mild protocol for the Ferrier rear-
rangement using an inexpensive and less polluting cata-
lyst.
It can be postulated that triflate salts release triflic acid
which catalyzes the allylic rearrangement leading to the
Ferrier product.14,15 As a cheaper alternative we have cho-
sen HClO4, the strongest mineral acid to catalyze this
transformation. In order to avoid the presence of water in
the reaction medium that certainly has a deleterious effect
on the formation of the product, HClO4 has been impreg-
nated over silica gel. HClO4/SiO2 acted as an insoluble
catalyst, which could be removed from the reaction mix-
ture by simple filtration. Recently HClO4/SiO2 has been
used to catalyze the acetylation of alcohols and phenols
using acetic acid.18
In a first set of experiments, triacetyl glucal was treated
with a batch of simple alcohols in acetonitrile by varying
the quantity of alcohols, catalyst and reaction tempera-
ture. After some experimentation, it has been found that
using 2.0 equivalent of alcohol in acetonitrile in the pres-
ence of 50.0 mg of HClO4–SiO2/mmol of the glycal at
room temperature produce 2,3-unsaturated glycosides in
excellent yields. In the case of triacetyl galactal the reac-
tions went smoothly under these conditions but the yields
were a bit inferior to its glucal counterpart. In most of the
cases, a mixture two anomers of 2,3-unsaturated glyco-
sides (a and b) were obtained, the ratio of which was de-
SYNTHESIS 2005, No. 2, pp 0260–0266
x
x
.
x
x
.2
0
0
4
Advanced online publication: 23.12.2004
DOI: 10.1055/s-2004-837297; Art ID: T05304SS
© Georg Thieme Verlag Stuttgart · New York

PAPER
Synthesis of 2,3-Unsaturated Glycopyranosides
261
completion of the reaction, the reaction mixture was filtered
through a celite bed and concentrated to dryness under reduced
pressure. The crude reaction mixture was purified over SiO2 using
hexane–EtOAc as eluent to furnish the desired 2,3-unsaturated gly-
coside as summarized in Table 1. Products of all known compounds
gave acceptable NMR spectra that matched with the data reported
in the literature. New compounds were characterized according to
identity and purity.
termined by comparing the integration values of the peaks
in 1H NMR, 13C NMR, HPLC and GC analysis (Table 1).
The a-configuration of the major product was confirmed
from the optical rotation values and positions of the ano-
meric protons in the 1H NMR and 13C NMR spectra. H-1
of a-glycoside occupies an up field position compared to
its b-isomer. For further confirmation, NOE experiment
was carried out, in which NOE was observed between H-
1 and H-4 in all glucal derived products and no NOE was
observed between H-1 and H-4 of galactal-derived prod-
ucts. From the NOE experiments a conclusion can be
drawn that in the case of 2,3-unsaturated glucosides H-1
and H-4 are on the same side and in the case of 2,3-unsat-
urated galactosides, H-1 and H-4 are on the opposite side,
which is possible only in the case of a-glycosides. Follow-
ing the same reaction conditions, substitution of simple al-
cohols by sugar acceptors led to the formation of
disaccharides containing 2,3-unsaturated sugars in rea-
sonably good yields.
Ethyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyra-
noside (3a)
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +91 (c = 1.0,
CHCl3).
IR (neat): 2979, 2900, 2371, 1743, 1441, 1374, 1235, 1108, 1048,
907 cm–1.
1H NMR (CDCl3): d =5.86 (br s, 2 H, H-2, H-3), 5.34–5.29 (dd, J =
9.5, 1.0 Hz, 1 H, H-4), 5.04 (br s, 1 H, H-1), 4.24–4.20 (m, 2 H,
CH2CH3), 4.14–4.11 (m, 1 H, H-5), 3.88–3.80 (m, 1 H, H-6), 3.59–
3.58 (m, 1 H, H-6), 2.09, 2.08 (2 × s, 6 H, 2 × COCH3), 1.25 (t, J =
7.5 Hz, 3 H, OCH2CH3).
13C NMR (CDCl3): d = 171.0, 170.5, 129.3, 128.4, 94.6, 67.2, 65.7,
64.8, 63.4, 21.2, 21.0, 15.6.
In conclusion, the present method of HClO4/SiO2 cata-
lyzed Ferrier rearrangement of acylated glycals provides
MS (FAB): m/z = 259 [M + 1]+, 213 [M – OCH2CH3]+, 215 [M –
an efficient protocol to prepare 2,3-unsaturated O-glyco- COCH3]+, 199 [M – CO2CH3]+, 111 [C6H7O2]+.
sides (Scheme 1).
Anal. Calcd for C12H18O6 (258): C, 55.81; H, 7.02. Found: C, 55.72;
H, 7.10.
AcO
O
AcO
AcO
HClO4/SiO2
CH3CN, r.t.
O
AcO
n-Butyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyr-
RXH
+
AcO
XR
anoside (3b)
25
X = O, S
R = Alkyl, glycosyl
X = O, S
R = Alkyl, glycosyl
Yellow oil; Rf 0.70 (hexane–EtOAc, 3:1); [a]D +37.5 (c = 1.0,
CHCl3).
IR (neat): 2924, 2853, 1743, 1639, 1373, 1232, 1043, 761 cm–1.
Scheme 1
1H NMR (CDCl3): d = 5.85 (br s, 2 H, H-2, H-3), 5.33–5.28 (dd,
J = 9.0, 1.0 Hz, 1 H, H-4), 5.02 (br s, 1 H, H-1), 4.23–4.19 (m, 2 H,
H-6), 4.13–4.0 (m, 1 H, H-5), 3.85–3.70 (m, 1 H, OCH2), 3.50–3.45
(m, 1 H, OCH2), 2.09, 2.08 (2 × s, 6 H, 2 × COCH3), 1.53–1.42 (m,
2 H, OCH2CH2CH2), 1.35–1.25 (m, 2 H, OCH2CH2CH2), 0.97–0.89
(t, J = 4.8 Hz, 3 H, CH3).
All the reactions were monitored by TLC over silica gel coated TLC
plates. The spots on TLC were visualized by warming ceric sulphate
[2% Ce(SO4)2 in 2 N H2SO4] sprayed plates on hot plate or in an
oven at about 100 °C. Silica gel 230–400 mesh was used for column
chromatography. FAB mass spectra were recorded on JEOL SX
102/DA-6000 mass using Ar/Xe (6 KV, 10 MA) as the FAB gas.
GC experiments were performed on a Perkin-Elmer auto system us-
ing OV-225 column and anhyd N2 as the carrier gas. HPLC experi-
ments were run on an analytical HPLC (Agilent 1100 series) by
using C18 LichroCART®-250-4 column (4.6 × 150 mm) with a sol-
vent mixture of CH3CN–H2O (10–100%) and a flow rate of 1.0 mL/
min at 220/254 UV absorbance. 1H and 13C NMR spectra were re-
corded on Brucker Advance DPX spectrometer at 200 MHz using
TMS as internal reference. Chemical shift value is expressed in
d (ppm). Elementary analysis was carried out on Carlo ERBA-1108
analyzer. Optical rotations were measured at 25 °C on a Rudolf Au-
topol III polarimeter. Commercially available grades of organic sol-
vents of adequate purity were used in many reactions. HClO4/SiO2
was prepared following the protocol described in the literature.18
13C NMR (CDCl3): d = 171.1, 170.6, 129.3, 128.4, 94.8, 67.3, 65.7,
64.8, 63.5, 30.0, 21.3, 21.1, 19.7, 14.2.
MS (FAB): m/z = 287 [M + 1]+, 243 [M – COCH3]+, 227 [M –
CO2CH3]+, 213 [M – OC4H9]+, 111 [C6H7O2]+.
Anal. Calcd for C14H22O6 (286): C, 58.73; H, 7.74. Found: C, 58.65;
H, 7.66.
Isopropyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
enopyranoside (3c)
Yellow oil; Rf 0.66 (hexane–EtOOAc, 3:1); [a]D25 +104.5 (c = 1.0,
CHCl3).
IR (neat): 3022, 2975, 2932, 1744, 1452, 1373, 1241, 1125, 1103,
1046, 982, 755 cm–1.
1H NMR (CDCl3): d = 5.85–5.81 (m, 2 H, H-2, H-3), 5.32–5.28 (dd,
J = 8.0, 1.2 Hz, 1 H, H-4), 5.13 (br s, 1 H, H-1), 4.23–4.14 (m, 3 H,
H-6, H-5), 4.02–3.96 [m, 1 H, CH(CH3)2], 2.09, 2.08 (2 × s, 6 H,
2 × COCH3), 1.27–1.24 [d, J = 4.0 Hz, 3 H, CH(CH3)2], 1.22–1.16
[d, J = 4.0 Hz, 3 H, CH(CH3)2].
13C NMR (CDCl3): d = 171.4, 170.7, 129.2, 128.9, 93.2, 71.1, 67.2,
65.8, 63.5, 23.9, 22.4, 21.3, 21.1.
Preparation of HClO4–SiO2 Catalyst; General Procedure
HClO4 (1.8 g, 12.5 mmol, as a 70% aq solution) was added to a sus-
pension of SiO2 (230–400 mesh, 23.7 g) in Et2O (70.0 mL). The
mixture was concentrated and the residue was heated at 100 °C for
72 h under vacuum to furnish HClO4/SiO2 (0.5 mmol/g) as a free
flowing powder; (50 mg = 0.025 mmol of HClO4).
MS (FAB): m/z = 273 [M + 1]+, 213 [M – OCH(CH3)2]+, 170 [M –
Alkyl 2,3-Dideoxy-a/b-D-glycoside (3); General Procedure
To a solution of tri-O-acetyl-D-glucal (272 mg, 1.0 mmol) and alco-
hol (2.0 mmol) in CH3CN (3.0 mL) was added HClO4/SiO2 (50.0
mg) and stirred at r.t. for the appropriate time (see Table 1). After
C3H7O – COCH3]+, 111 [C6H7O2]+.
Anal. Calcd for C13H20O6 (272): C, 57.34; H, 7.40. Found: C, 57.40;
H, 7.50.
Synthesis 2005, No. 2, 260–266 © Thieme Stuttgart · New York

262
A. K. Misra et al.
PAPER
Allyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyra-
J = 12.0 Hz, 1 H, PhCH2), 4.27–4.14 (m, 2 H, H-6), 4.11–4.08 (m,
1 H, H-5), 2.08, 2.06 (2 × s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 171.2, 170.7, 130.8–126.5 (aromatic car-
bons, C-2, C-3), 94.1, 71.7, 69.9, 67.6, 64.7, 21.3, 21.1.
MS (FAB): m/z = 321 [M + 1]+, 305 [M – CH3]+, 290 [M – 2 ×
CH3]+, 276 [M – OCO]+, 229 [M – PhCH2]+, 218 [M – CH3CO2 –
CH3CO]+, 213 [M – PhCH2O]+, 197 [C13H9O2]+, 189 [C8H13O5]+,
153 [C8H9O3]+, 111 [C6H7O2]+.
noside (3d)
25
Yellow oil; Rf 0.85 (hexane–EtOAc, 3:1); [a]D +80.5 (c = 2.0,
CHCl3).
IR (neat): 2923, 2375, 1744, 1372, 1233, 1038 cm–1.
1H NMR (CDCl3): d = 6.10–5.90 (m, 1 H, CH=CH2), 5.87–5.85 (m,
2 H, H-2, H-3), 5.35–5.33 (dd, J = 8.6, 1.2 Hz, 1 H, H-4), 5.31–5.18
(m, 2 H, CH=CH2), 5.07 (br s, 1 H, H-1), 4.32–4.24 (m, 1 H, H-5),
4.24–4.20 (m, 2 H, H-6), 4.13–4.00 (m, 2 H), 2.10, 2.08 (2 × s, 6 H,
2 × COCH3).
13C NMR (CDCl3): d = 171.0, 170.6, 134.5, 129.6, 126.4, 117.8,
94.0, 69.6, 67.4, 65.7, 63.4, 21.3, 21.1.
Anal. Calcd for C17H20O6 (320): C, 63.74; H, 6.29. Found: C, 63.68;
H, 6.38.
6-O-(4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyra-
nosyl)-1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (3h)
White solid; mp 137 °C [Lit. 136–38 °C];4a Rf 0.60 (hexane–EtOAc,
3:1); [a]D25 +16.8 (c = 1.0, CHCl3).
MS (FAB): m/z = 271 [M + 1]+, 227 [M – COCH3]+, 213 [M –
C3H5O]+, 211 [M – CO2CH3]+, 111 [C6H7O2]+.
Anal. Calcd for C13H18O6 (270): C, 57.77; H, 6.71. Found: C, 57.69;
H, 6.78.
IR (KBr): 2993, 2927, 2372, 1742, 1596, 1382, 1229, 1069, 1044,
1003, 894 cm–1.
Propargyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
1H NMR (CDCl3): d = 5.86 (br s, 2 H, H-2¢, H-3¢), 5.51 (d, J = 4.7
Hz, 1 H, H-1), 5.34–5.29 (dd, J = 8.0, 1.2 Hz, 1 H, H-4¢), 5.09 (br s,
1 H, H-1¢), 4.63–4.59 (dd, J = 8.0, 2.4 Hz, 1 H, H-3), 4.37–4.25 (m,
3 H, H-5¢, H-6¢), 4.19–4.11 (m, 2 H, H-6), 4.04–3.97 (m, 1 H), 3.91–
3.83 (m, 1 H), 3.79–3.71 (m, 1 H, H-5), 2.09, 2.08 (2 × s, 6 H, 2 ×
COCH3), 1.53 [s, 3 H, CH(CH3)2], 1.44 [s, 3 H, CH(CH3)2], 1.34 [s,
6 H, CH(CH3)2].
13C NMR (CDCl3): d = 171.2, 170.6, 129.6, 128.1, 109.7, 108.9,
96.7, 94.9, 71.3, 70.9 (2 × C), 67.5, 67.4, 66.6, 65.7, 63.3, 26.4
(2 × C), 25.3, 24.9, 21.3, 21.1.
enopyranoside (3e)
25
Yellow oil; Rf 0.85 (hexane–EtOAc, 3:1); [a]D +42.5 (c = 1.0,
CHCl3).
IR (neat): 3281, 1743, 1373, 1237, 1041, 966, 733 cm–1.
1H NMR (CDCl3): d = 5.90–5.85 (m, 2 H, H-2, H-3), 5.36–5.31 (dd,
J = 9.6, 1.2 Hz, 1 H, H-4), 5.24 (br s, 1 H, H-1), 4.36–4.31 (m, 2 H),
4.28–4.20 (m, 2 H), 4.13–4.04 (m, 1 H, H-5), 2.50–2.48 (t, J = 2.2
Hz, 1 H, CH≡C), 2.10, 2.08 (2 × s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 171.0, 170.5, 130.1, 127.6, 93.1, 79.5, 75.2,
67.6, 66.6, 63.1, 55.4, 21.2, 21.1.
MS (FAB): m/z = 471 [M – 1]+, 457 [M – CH3]+, 442 [M – 2 ×
CH3]+, 414 [M – C3H6O]+, 383 [M – C3H6O2 – CH3]+, 340 [M –
CH3CO2 – CH3CO – 2 × CH3]+, 213 [C10H13O5]+, 153 [C8H9O3]+,
111 [C6H7O2]+.
MS (FAB): m/z = 269 [M + 1]+, 225 [M – COCH3]+, 213 [M –
C3H3O]+, 209 [M – CO2CH3]+, 111 [C6H7O2]+.
Anal. Calcd for C13H16O6 (268): C, 58.20; H, 6.01. Found: C, 58.12;
H, 6.10.
Anal. Calcd for C22H32O11 (472): C, 55.92; H, 6.83. Found: C,
55.85; H, 6.90.
Octyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyra-
Methyl 6-O-(4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
enopyranosyl)-2,3,4-tri-O-benzyl-a-D-glucopyranoside (3i)
noside (3f)
25
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +29.7 (c = 1.0,
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +61.2 (c = 1.0,
CHCl3).
CHCl3).
IR (neat): 2928, 2375, 1743, 1370, 1231, 1033, 766, 700 cm–1.
IR (neat): 3430, 2930, 2372, 1743, 1654, 1372, 1225, 1039, 769
cm–1.
1H NMR (CDCl3): d = 7.33–7.29 (m, 15 H, aromatic protons), 5.85
(m, 2 H, H-2¢, H-3¢), 5.34–5.28 (dd, J = 8.0, 1.5 Hz, 1 H, H-4¢) 5.10
(br s, 1 H, H-1¢), 5.01–4.67 (3 × dd, 3 × J = 11.6 Hz, 6 H, 3 ×
PhCH2), 4.63–4.60 (m, 2 H), 4.22–4.20 (dd, J = 8.0, 1.2 Hz, 1 H),
4.05–3.96 (m, 4 H), 3.80–3.64 (m, 2 H), 3.62–3.40 (m, 1 H, H-5),
3.37 (s, 3 H, OCH3), 2.06, 1.99 (2 × s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 171.1, 170.6, 139.1, 138.8, 138.5, 128.8,
128.7–127.9 (aromatic carbons), 98.5, 95.2, 82.4, 80.5, 76.2, 75.3,
73.7, 70.4, 67.4, 65.6, 63.1, 55.6, 21.4, 21.1.
MS (FAB): m/z = 677 [M + 1]+, 585 [M – CH2Ph]+, 551 [M –
OCH2Ph – H2O]+, 526 [M – OCH2Ph – COCH3]+, 462 [M – 2 ×
OCH2Ph]+, 419 [M – 2 × OCH2Ph – COCH3]+, 385 [M – 3 ×
CH2Ph – H2O]+, 341 [M – 3 × CH2Ph – H2O – COCH3 – 1]+, 327
[M – 2 × OCH2Ph – CH2Ph – OCO]+, 312 [C15H20O7]+, 281
[C14H17O6]+, 213 [C10H13O5]+, 111 [C6H7O2]+.
1H NMR (CDCl3): d = 5.86–5.84 (m, 2 H, H-2, H-3), 5.33–5.29 (dd,
J = 8.0, 1.0 Hz, 1 H, H-4), 5.02 (br s, 1 H, H-1), 4.25–4.19 (m, 2 H,
H-6), 4.14–4.01 (m, 1 H, H-5), 3.79–3.75 (m, 1 H, OCH2C7H15),
3.53–3.48 (m, 1 H, OCH2C7H15), 2.10, 2.08 (2 × s, 6 H, 2 ×
COCH3), 1.70–1.58 (m, 2 H, octyl), 1.28 (m, 10 H, octyl), 0.91–
0.85 (t, J = 6.8 Hz, 3 H, CH3).
13C NMR (CDCl3): d = 171.2, 170.7, 129.3, 128.4, 94.8, 69.4, 67.3,
64.8, 63.4, 32.2, 30.1, 29.8, 29.6, 26.6, 23.0, 21.3, 21.1, 14.4.
MS (FAB): m/z = 343 [M + 1]+, 213 [M – Ooctyl]+, 153 [C8H9O3]+,
111 [C6H7O2]+.
Anal. Calcd for C18H30O6 (342): C, 63.14; H, 8.83. Found: C, 63.07;
H, 8.90.
Benzyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-enopyr-
anoside (3g)
Anal. Calcd for C38H44O11 (676): C, 67.44; H, 6.55. Found: C,
67.38; H, 6.62.
25
Yellow oil; Rf 0.70 (hexane–EtOAc, 3:1); [a]D +8.4 (c = 1.0,
CHCl3).
3-O-Benzyl-1,2-O-isopropylidene-5-O-(4,6-di-O-acetyl-2,3-
dideoxy-a-D-erythro-hex-2-enopyranosyl)-a-D-xylofuranose
(3j)
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +15.0 (c = 1.0,
CHCl3).
IR (neat): 3032, 2904, 1729, 1453, 1374, 1226, 1102, 1037, 971,
910, 738, 701, 604 cm–1.
1H NMR (CDCl3): d = 7.36–7.31 (m, 5 H, C6H5), 5.97–5.87 (m, 2
H, H-2, H-3), 5.35–5.30 (dd, J = 9.4, 1.0 Hz, 1 H, H-4), 5.12 (br s,
1 H, H-1), 4.83–4.77 (d, J = 11.7 Hz, 1 H, PhCH2), 4.62–4.56 (d,
25
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Synthesis of 2,3-Unsaturated Glycopyranosides
263
IR (neat): 3022, 2373, 1740, 1375, 1218, 1076, 1045, 760, 699 cm–1.
H, H-2), 5.84–5.78 (dd, J = 10.1, 1.3 Hz, 1 H, H-3), 5.65 (br s, 1 H,
H-1), 5.37–5.32 (dd, J = 9.3, 1.6 Hz, 1 H, H-4), 4.49–4.42 (m, 1 H,
H-5), 4.30–4.17 (m, 2 H, H-6), 2.30 (s, 3 H, C6H4CH3), 2.07, 2.05
(2 × s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 170.9, 170.5, 138.2, 132.8 (2 × C), 130.1
(3 × C), 129.1, 127.8, 84.4, 67.6, 65.6, 63.5, 21.5, 21.3, 21.1.
MS (FAB): m/z = 337 [M + 1]+, 321 [M – CH3]+, 277 [M –
CO2CH3]+, 235 [M – CO2CH3 – COCH3 + 1]+, 213 [M – SC6H5 –
CH3]+, 153 [C8H9O3]+, 111 [C6H7O2]+.
1H NMR (CDCl3): d = 7.35–7.32 (m, 5 H, aromatic protons), 5.94–
5.92 (d, J = 4.0 Hz, 1 H, H-1), 5.84 (m, 1 H, H-2¢), 5.74 (m, 1 H, H-
3¢), 5.39–5.30 (dd, J = 7.6, 1.2 Hz, 1 H, H-4¢), 4.99 (br s, 1 H, H-1¢),
4.85–4.72 (d, J = 12 Hz, 1 H, PhCH2), 4.51–4.45 (d, J = 12 Hz, 1 H,
PhCH2), 4.40 (m, 1 H, H-5), 4.25–4.16 (m, 3 H), 4.01–3.95 (m, 1
H), 3.79–3.77 (dd, J = 8.0, 3.0 Hz, 1 H), 2.09, 2.07 (2 × s, 6 H, 2 ×
COCH3), 1.49, 1.32 [2 × s, 6 H, CH (CH3)2].
13C NMR (CDCl3): d = 171.2, 170.7, 137.8, 130.8-127.9 (aromatic
carbons, C-2¢, C-3¢), 112.1, 105.5, 94.9, 83.1, 81.9, 79.2, 72.3, 67.3,
66.1, 65.6, 61.3, 27.2, 26.7, 21.3, 21.1.
MS (FAB): m/z = 493 [M + 1]+, 462 [M – 2 × CH3]+, 401 [M –
CH2Ph]+, 385 [M – OCH2Ph]+, 339 [C6H19O8]+, 326 [C15H18O8]+,
267 [C13H15O6]+, 252 [C12H12O6]+, 213 [C10H13O5]+, 139 [C7H7O3]+,
111 [C7H6O2]+.
Anal. Calcd for C17H20O5S (336): C, 60.70; H, 5.99. Found: C,
60.77; H, 6.10.
Isopropyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-enopyr-
anoside (3n)
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D –11.6 (c = 1.0,
CHCl3).
Anal. Calcd for C25H32O10 (492): C, 60.97; H, 6.55. Found: C,
60.91; H, 6.62.
IR (neat): 2371, 1741, 1637, 1372, 1229, 1021, 769, 699 cm–1.
1H NMR (CDCl3): d = 6.19–6.07 (m, 1 H, H-2), 6.03–5.95 (m, 1 H,
H-3), 5.18–5.17 (d, J = 2.7 Hz, 1 H, H-1), 5.04–5.01 (dd, J = 5.1,
2.5 Hz, 1 H, H-4), 4.40–4.38 (m, 1 H, H-5), 4.24–4.20 (m, 2 H, H-
6), 4.08–3.98 [m, 1 H, CH(CH3)2], 2.10, 2.08 (2 × s, 6 H, 2 ×
COCH3), 1.27–1.24 (d, J = 4.0 Hz, 3 H), 1.19–1.16 (d, J = 4.0 Hz,
3 H).
Ethyl Glycolyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-erythro-hex-2-
eno-1-thiopyranoside (3k)
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +93.0 (c = 1.0,
CHCl3).
IR (neat): 2978, 2939, 1744, 1597, 1379, 1224, 1128, 1072, 1042,
979, 956, 832, 782 cm–1.
13C NMR (CDCl3): d = 171.0, 170.8, 131.6, 125.3, 92.8, 70.9, 67.0,
63.4, 63.3, 23.8, 22.9, 21.2, 21.1.
1H NMR (CDCl3): d = 5.95–5.87 (m, 1 H, H-2), 5.80–5.75 (m, 1 H,
H-3), 5.68 (br s, 1 H, H-1), 5.35 (dd, J = 8.0, 1.0 Hz, 1 H, H-4),
4.25–4.07 (m, 5 H, H-6, H-5, OCH2CH3), 3.49–3.17 (q, J = 16.0 Hz
each, 2 H, SCH2), 2.03, 2.02 (2 × s, 6 H, 2 × COCH3), 1.22 (t, J =
7.0 Hz, 3 H, CH2CH3).
13C NMR (CDCl3): d = 170.9, 170.4 (2C), 128.4, 128.3, 80.1, 67.5,
65.4, 63.1, 61.7, 33.0, 21.2, 21.0, 14.4.
MS (FAB): m/z = 333 [M + 1]+, 273 [M – CO2CH3]+, 230 [M –
CO2CH3 – CH3CO]+, 213 [C10H13O5]+, 153 [C8H9O3]+, 111
[C6H7O2]+.
MS (FAB): m/z = 273 [M + 1]+, 213 [M – OCH(CH3)2]+, 170 [M –
C3H7O – COCH3]+, 111 [C6H7O2]+.
Anal. Calcd for C13H20O6 (272): C, 57.34; H, 7.40. Found: C, 57.26;
H, 7.50.
Allyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-enopyrano-
side (3o)
25
Yellow oil; Rf 0.75 (hexane–EtOAc, 3:1); [a]D –7.6 (c = 1.0,
CHCl3).
Anal. Calcd for C14H20O7S (332): C, 50.59; H, 6.07. Found: C,
50.50; H, 6.13.
IR (neat): 2923, 2375, 1744, 1372, 1233, 1038 cm–1.
1H NMR (CDCl3): d = 6.15–6.05 (m, 2 H, H-2, H-3), 6.0–5.85 (m,
1 H, CH=CH2), 5.34 (d, J = 1.2 Hz, 1 H, H-1), 5.25–5.23 (m, 1 H,
H-4), 5.18–5.01 (m, 2 H, CH2=CH), 4.45–4.27 (m, 2 H, OCH2),
4.25–4.10 (m, 2 H, H-6), 4.05–3.95 (m, 1 H, H-5), 2.08, 2.06 (2 ×
s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 170.6, 170.4, 134.5, 130.9, 125.5, 117.7,
93.4, 69.1, 67.1, 63.0 (2 × C), 20.9 (2 × C).
Phenyl 4,6-Di-O-acetyl-2,3-dideoxy-erythro-hex-2-eno-1-thio-
a-D-pyranoside (3l)
25
Yellow oil; Rf 0.76 (hexane–EtOAc, 3:1); [a]D +28.2 (c = 1.0,
CHCl3).
IR (neat): 2954, 1744, 1371, 1232, 1055, 775, 747, 693 cm–1.
1H NMR (CDCl3): d = 7.57–7.26 (m, 5 H, C6H5), 6.10–6.02 (m, 1
H, H-3), 5.89–5.84 (m, 1 H, H-2), 5.76 (br s, 1 H, H-1), 5.41–5.35
(dd, J = 9.4, 1.4 Hz, 1 H, H-4), 4.55–4.42 (m, 1 H, H-5), 4.34–4.23
(m, 2 H, H-6), 2.10, 2.06 (2 × s, 6 H, 2 × COCH3).
13C NMR (CDCl3): d = 170.6, 170.2, 131.9–128.0 (aromatic car-
bons, C-2, C-3), 84.1, 65.6, 63.5, 62.6, 21.4, 21.1.
MS (FAB): m/z = 321 [M – 1]+, 263 [M – CO2CH3]+, 220 [M –
CH3CO2 – CH3CO]+, 213 [M – SC6H5]+, 203 [C13H15O2]+, 187
[C8H11O5]+, 153 [C8H9O3]+, 111 [C6H7O2]+.
MS (FAB): m/z = 271 [M + 1]+, 227 [M – COCH3]+, 213 [M –
C3H5O]+, 211 [M – CO2CH3]+, 111 [C6H7O2]+.
Anal. Calcd for C13H18O6 (270): C, 57.77; H, 6.71. Found: C, 57.71;
H, 6.80.
Benzyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-enopyra-
noside (3p)
25
Yellow oil; Rf 0.70 (hexane–EtOAc, 3:1); [a]D –13.1 (c = 1.0,
CHCl3).
Anal. Calcd for C16H18O5S (322): C, 59.61; H, 5.63. Found: C,
59.55; H, 5.70.
IR (neat): 3030, 2905, 1730, 1456, 1370, 1222, 1100, 1032, 976,
913, 739, 700, 607 cm–1.
1H NMR (CDCl3): d = 7.35–7.28 (m, 5 H, C6H5), 6.18–6.08 (m, 1
H, H-2), 6.06–5.95 (m, 1 H, H-3), 5.15 (d, J = 2.6 Hz, 1 H, H-1),
5.04–5.00 (dd, J = 5.0, 2.4 Hz, 1 H, H-4), 4.84–4.78 (d, J = 11.6 Hz,
1 H, CH2Ph), 4.60–4.55 (d, J = 11.6 Hz, 1 H, CH2Ph), 4.45–4.36 (m,
1 H, H-5), 4.24–4.20 (m, 2 H, H-6), 2.07, 2.03 (2 × s, 6 H, 2 ×
COCH3).
para-Methylphenyl 4,6-Di-O-acetyl-2,3-dideoxy-erythro-hex-2-
eno-1-thio-a-D-pyranoside (3m)
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D +163.0 (c = 1.0,
CHCl3).
25
IR (neat): 2925, 2373, 1745, 1643, 1371, 1235, 1048, 811, 759 cm–1.
1H NMR (CDCl3): d = 7.44–7.41 (m, 2 H, aromatic proton), 7.17–
7.07 (m, 2 H, aromatic protons), 6.05–5.95 (dd, J = 10.1, 2.5 Hz, 1
13C NMR (CDCl3): d = 171.0, 170.8, 130.9–125.7 (aromatic car-
bons, C-2, C-3), 93.3, 70.6, 67.4, 63.3 (2 × C), 21.2 (2 × C).
Synthesis 2005, No. 2, 260–266 © Thieme Stuttgart · New York

264
A. K. Misra et al.
PAPER
MS (FAB): m/z = 321 [M + 1]+, 305 [M – CH3]+, 290 [M – 2 ×
CH3]+, 229 [M – PhCH2]+, 218 [M – CH3CO2 – CH3CO], 213 [M –
PhCH2O]+, 197 [C13H9O2]+, 189 [C8H13O5]+, 153 [C8H9O3]+, 111
[C6H7O2]+.
6-O-(4,6-Di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-enopyrano-
syl)-1,2:3,4-di-O-isopropylidene-a-D-galactopyranose (3r)
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D –8.7 (c = 1.0,
CHCl3).
Anal. Calcd for C17H20O6 (320): C, 63.74; H, 6.29. Found: C, 63.67;
H, 6.35.
IR (neat): 2996, 2953, 2374, 1741, 1631, 1591, 1381, 1247, 1068,
1009, 893 cm–1.
1H NMR (CDCl3): d = 6.15–5.95 (m, 2 H, H-2¢, H-3¢), 5.52 (d, J =
5.0 Hz, 1 H, H-1), 5.12 (d, J = 2.2 Hz, 1 H, H-1¢), 5.03–5.01 (m, 1
H, H-4), 4.61–4.59 (dd, J = 7.6, 2.4 Hz, 1 H, H-3), 4.40–4.29 (m, 2
H), 4.24–4.20 (m, 3 H), 4.0–3.95 (m, 1 H, H-5), 3.85–3.76 (m, 2 H),
2.08 (2 × s, 6 H, 2 × COCH3), 1.53, 1.44 [2 × s, 6 H, CH(CH3)2],
1.34, 1.33 [2 × s, 6 H, CH(CH3)2].
13C NMR (CDCl3): d = 170.9, 170.6, 130.9, 125.5, 109.6, 108.8,
96.7, 94.5, 71.3, 71.0 (2 × C), 67.1 (2 × C), 66.5, 63.1, 62.9, 26.4,
26.3, 25.3, 24.8, 21.1 (2 × C).
MS (FAB): m/z = 471 [M – 1]+, 457 [M – CH3]+, 442 [M – 2 ×
CH3]+, 414 [M – C3H6O]+, 383 [M – C3H6O2 – CH3]+, 368 [M –
CH3CO2 – CH3CO – 2 × CH3]+, 213 [C10H13O5]+, 153 [C8H9O3]+,
111 [C6H7O2]+.
Octyl 4,6-Di-O-acetyl-2,3-dideoxy-a-D-threo-hex-2-enopyrano-
side (3q)
25
Yellow oil; Rf 0.65 (hexane–EtOAc, 3:1); [a]D –3.3 (c = 1.0,
CHCl3).
IR (neat): 3432, 2933, 2370, 1740, 1656, 1375, 1226, 1033, 766
cm–1.
1H NMR (CDCl3): d = 6.15–5.95 (m, 2 H, H-2, H-3), 5.34 (br s, 1
H, H-1), 5.10–4.99 (m, 1 H), 4.40–4.30 (m, 1 H, H-5), 4.14–4.08
(m, 2 H, H-6), 3.60–3.41 (m, 2 H, octyl), 2.07, 1.98 (2 × s, 6 H, 2 ×
COCH3), 1.60–1.54 (m, 2 H, octyl), 1.30 (m, 10 H, octyl), 0.88 (t,
J = 5.2 Hz, 3 H, CH3).
13C NMR (CDCl3): d = 170.8, 170.5, 131.2, 125.4, 97.8, 67.2, 66.7,
63.3, 62.9, 32.2, 30.1, 29.8, 29.6, 26.6, 23.0, 21.3, 21.2, 14.4.
Anal. Calcd for C22H32O11 (472): C, 55.92; H, 6.83. Found: C,
55.86; H, 6.91.
MS (FAB): m/z = 343 [M + 1]+, 213 [M – OC8H17]+, 198
[C11H18O3]+, 153 [C8H9O3]+, 111 [C6H7O2]+.
Anal. Calcd for C18H30O6 (342): C, 63.14; H, 8.83. Found: C, 63.20;
H, 8.90.
Table 1 HClO4–SiO2 Catalyzed Ferrier Rearrangements of Acetyl Glycals Towards the Formation of 2,3-Unsaturated Glycosides
Entry Glycals (1)
Acceptors (2)
Products
Time (min)
20
Yield (%)
85
a/b
7:1
Ref
4a
a
C2H5OH
OAc
OAc
AcO
AcO
O
O
AcO
AcO
AcO
OC2H5
OC4H9
b
c
C4H9OH
OAc
30
30
80
90
3:1
3:1
19
4a
OAc
O
AcO
AcO
O
(CH3)2CHOH
OAc
OAc
O
O
AcO
AcO
OCH(CH3)2
d
e
CH2=CHCH2OH
60
60
85
76
6:1
20
21
OAc
OAc
O
O
AcO
AcO
AcO
AcO
OCH2CH=CH2
CH≡CCH2OH
11:1
OAc
OAc
O
O
AcO
AcO
O
f
C8H17OH
60
45
90
85
75
58
3:1
6:1
5:1
19
21
4a
OAc
OAc
O
O
AcO
AcO
AcO
AcO
OC8H17
g
h
C6H5CH2OH
OAc
OAc
O
O
AcO
AcO
OCH2C6H5
O
O
O
OAc
O
OH
OAc
O
O
O
AcO
AcO
O
AcO
O O
O
O
O
Synthesis 2005, No. 2, 260–266 © Thieme Stuttgart · New York

PAPER
Synthesis of 2,3-Unsaturated Glycopyranosides
265
Table 1 HClO4–SiO2 Catalyzed Ferrier Rearrangements of Acetyl Glycals Towards the Formation of 2,3-Unsaturated Glycosides
(continued)
Entry Glycals (1)
Acceptors (2)
Products
Time (min)
30
Yield (%)
65
a/b
8:1
Ref
–
i
OH
OAc
OAc
O
O
AcO
AcO
BnO
O
AcO
AcO
BnO
O
BnO
OCH3
O
BnO
OCH3
OBn
BnO
j
O
OBn
50
68
5:1
–
–
OAc
OAc
HO
O
AcO
AcO
O
O
O
OBn
O
O
O
O
k
l
SCH2COOEt
C6H5SH
OAc
30
20
72
78
80
82
1:0
12:1
6:1
OAc
O
AcO
AcO
O
AcO
AcO
SCH2COOEt
OAc
22, 23
OAc
O
AcO
AcO
O
SC6H5
m
n
4-(CH3)-C6H4SH
(CH3)2CHOH
OAc
20
–
–
OAc
O
AcO
AcO
O
AcO
AcO
S-C6H4-(4-CH3)
120
1:0
OAc
OAc
O
AcO
AcO
O
OCH(CH3)2
o
CH2=CHCH2OH
C6H5CH2OH
OAc
90
80
76
76
14:1
1:0
12b
–
OAc
O
AcO
AcO
O
AcO
AcO
OCH2CH=CH2
p
OAc
O
OAc
AcO
AcO
O
OCH2C6H5
q
r
C8H17OH
90
60
78
62
1:1
1:0
–
–
OAc
OAc
O
AcO
AcO
O
AcO
AcO
OC8H17
O
OAc
O
O
OAc
O
OH
O
O
O
O
AcO
AcO
O
O
O
O
O
Carbohydr. Res. 2001, 332, 335.
Acknowledgment
(3) (a) Holder, N. Chem. Rev. 1982, 82, 287. (b) Liu, Z. J.;
Zhou, M.; Min, J. M.; Zhang, L. H. Tetrahedron: Asymmetry
1999, 10, 2119. (c) Brito, T. M. B.; Silva, L. P.; Siqueira, V.
L.; Srivastava, R. M. J. Carbohydr. Chem. 1999, 18, 609.
(4) (a) Ferrier, R. J.; Prasad, N. J. Chem. Soc. C 1969, 570.
(b) Ferrier, R. J. Top. Curr. Chem. 2001, 215, 153.
(5) (a) Descotes, G.; Martin, J.-C. Carbohydr. Res. 1977, 56,
168. (b) Klaffke, W.; Pudlo, P.; Springer, D.; Thiem, J.
Liebigs Ann. Chem. 1991, 6, 509.
Instrumentation facilities from SAIF, CDRI are gratefully acknow-
ledged. P. T. thanks CSIR, New Delhi for providing a fellowship.
This project was partly funded by DST, New Delhi (Project no. SR/
FTP/CSA-10/2002), India. The authors thank Dr. B. Kundu, CDRI
for his help and support to perform HPLC experiments. The authors
thank referees for their valuable comments to improve the quality of
the manuscript.
(6) (a) Grynkiewiez, G.; Priebe, W.; Zamojski, A. Carbohydr.
Res. 1979, 68, 33. (b) Bhate, P.; Horton, D.; Priebe, W.
Carbohydr. Res. 1985, 144, 331.
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Synthesis 2005, No. 2, 260–266 © Thieme Stuttgart · New York