The use of ultrastable y zeolites in the Ferrier rearrangement of acetylated and benzylated glycals

Article abstract of DOI:10.1039/b921051b

The Ferrier rearrangement of a selection of protected glycals was successfully performed using a commercially available H-USY zeolite CBV-720 as catalyst, selected after screening a range of similar catalysts. By incorporating either alcohols, thiophenol, trimethylsilyl azide or allyltrimethylsilane in the reaction it was shown that a range of O-, S-, N- and C-glycosides could be formed. With benzylated glucal and galactal in particular, use of the CBV-720 catalyst led to significantly higher yields of the 2,3-dehydroglycosides than previously reported.

Full text of DOI:10.1039/b921051b

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www.rsc.org/greenchem | Green Chemistry
The use of ultrastable Y zeolites in the Ferrier rearrangement of acetylated
and benzylated glycals
Pieter Levecque,a,b David W. Gammon,*a Pierre Jacobs,b Dirk De Vosb and Bert Selsb
Received 8th October 2009, Accepted 27th January 2010
First published as an Advance Article on the web 8th March 2010
DOI: 10.1039/b921051b
The Ferrier rearrangement of a selection of protected glycals was successfully performed using a
commercially available H-USY zeolite CBV-720 as catalyst, selected after screening a range of
similar catalysts. By incorporating either alcohols, thiophenol, trimethylsilyl azide or
allyltrimethylsilane in the reaction it was shown that a range of O-, S-, N- and C-glycosides could
be formed. With benzylated glucal and galactal in particular, use of the CBV-720 catalyst led to
significantly higher yields of the 2,3-dehydroglycosides than previously reported.
long reaction times, unsatisfactory yields, low stereoselectivity,
the requirement for an excess of promoter (BF3(OEt)2), high
Introduction
The Ferrier rearrangement1 is well documented and pro-
cost (triflates), risk of explosion, requirements for large amounts
vides easy access to 2,3-unsaturated glycals or pseudoglycals
of catalyst, limited reusability of the catalyst, and activity
(Scheme 1). These are versatile intermediates in the total syn-
restricted to certain protecting groups on the substrates or
thesis of several biologically active natural products, including
certain types of nucleophile. There is therefore as yet no truly
antibiotics, antiviral and antitumor agents.2 Following the early
general methodology for the Ferrier rearrangement.
studies on the Ferrier rearrangement using simple Lewis acids
With the current movement towards more economically and
such as BF3, considerable attention has been given to investigat-
environmentally sustainable processes the microporous and
ing alternative catalysts for this reaction. These are mainly ho-
mesoporous materials like zeolites are emerging as promising
mogeneous catalysts and include InCl3,3 ZrCl4,4 AuCl3,5 TiCl4,6
catalysts in chemical processes relevant to the fine chemicals and
NbCl5,7 ZnCl2,8 FeCl3,9 CeCl3·7H2O,10 BiCl3,11 InBr3 and
12
pharmaceutical industry,40 and their application as catalysts in
LiBF4;13 metal triflates like: Dy(OTf)3,14 Er(OTf)3,15 In(OTf)3,16
reactions of carbohydrates has been recently reviewed.41 Their
Sc(OTf)3 and Yb(OTf)3;18 TMSOTf,19 BF3·Et2O,20 ceric am-
17
low cost and easy removal from reaction mixtures present sig-
monium nitrate (CAN),21 I2 (NIS),22 ZnR,23 InR,24 B(C6F5)3,25
nificant advantages. These considerations, and our own interest
Pd(OAc)2,26 POM (potassium dodecatungstocobaltate trihy-
in developing alternative catalytic processes for classic reactions
drate, K5CoW12O44·3H2O),27 FeSO4.xH2O,28 Fe(NO3)3·9H2O,29
in carbohydrate chemistry,42 have led to this investigation of a
Bi(NO3)3·5H2O,29,30 La(NO3)2,31 reduced Ni with Grignard
selection of commercially available zeolitic materials, including
reagent32 and DDQ.33 A few effective heterogeneous catalysts
of the ultrastable Y zeolites (H-USY), as catalysts for the Ferrier
have been developed, including Montmorillonite K-10,34 silica
rearrangement. A selection of acetylated or benzylated glycals
gel,35 HClO4–SiO2,36 phosphomolybdic acid (PMA) on SiO2,37
were combined with a variety of nucleophiles in the presence of
Amberlyst-15,38 and HY.39 However, there are a number of
general limitations associated with many of these catalysts.
the catalyst, in order to evaluate the scope of this methodology
for preparation of 2,3-unsaturated C-, N-, O- and S-glycosides.
Firstly, the homogeneous catalysts have the problem of sep-
as summarized in Scheme 2.
aration from the final products, an issue which has both
environmental and economical consequences. In addition other
limitations include the need for high temperatures, strong acidity
(Mont. K-10, TiCl4, BF3(OEt)2), strong oxidizing conditions
(DDQ), incompatibility with acid-sensitive protecting groups,
Scheme 2 General scheme for the Ferrier rearrangement with zeolites.
Scheme 1 Ferrier rearrangement with acetylated glucal (1).
Results and discussion
aDepartment of Chemistry, University of Cape Town, Private Bag,
Screening of zeolites
Rondebosch, 7001, South Africa. E-mail: david.gammon@uct.ac.za;
Fax: +27-21-650-5195
bCentre for Surface Chemistry and Catalysis, K.U.Leuven, Kasteelpark
Arenberg 23, 3001, Heverlee, Belgium
A selection of acidic solids, ranging from more Brønsted-
acidic to more Lewis-acidic materials was evaluated for catalytic
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Table 2 Evaluation of initial activity of CBV series zeolites for the
Ferrier rearrangement
activity in the screening reaction of acetylated glucal with benzyl
alcohol at 30 ◦C in THF (Scheme 3).
Conv. (%)
Zeolite
10 mina
10 minb
20 minb
CBV-600
CBV-712
CBV-720
CBV-760
CBV-780
—
10
14
7
—
62
94
—
85
<1
76
100
—
Scheme 3 Overview of the screening reaction.
6
90
Acetylated glucal (1) has been recognized as one of the
preferred starting materials for this reaction due to the acetate
being a good leaving group, with the reaction understood to
proceed via the formation of a cyclic allylic oxocarbenium ion
intermediate (Scheme 4).1,20c
a Conditions: dry zeolite (22.5 wt%, 0.0612 g), THF (5 ml), acetylated
glucal (1 mmol, 0.272 g) and BnOH (144.8 ml, 1.4 eq.). b Conditions: dry
zeolite (90 wt%, 0.0612 g), THF (5 ml), acetylated glucal (0.25 mmol,
0.068 g) and BnOH (36.2 ml, 1.4 eq.). The zeolite was removed by
filtration after the indicated time, and solvent and benzyl alcohol
removed by distillation under vacuum. Conversions were determined
by comparison of integrals of selected signals in the 1H NMR spectra of
the product mixtures.
Scheme 4 Formation of allylic oxocarbenium ion from acetylated
glucal in the Ferrier rearrangement.
presence of pores of mesoporous dimensions in the former
as opposed to microporous dimensions in the latter. Zeolites
in the CBV series arise from H-USY zeolites that have been
treated with steam and leached with mineral acid. Starting
from the mother Y zeolite (CBV-300), CBV-600 is obtained
by steam treatment at 600 ◦C. Mild acid leaching of CBV-
600 affords CBV-712. CBV-720, CBV-760 and CBV-780 are
obtained by a second steam treatment at higher temperatures
and leaching with mineral acids. The combination of leaching
and steam treatment results in materials with disrupted crystal
morphologies, with more cracks and voids (mesoporosity) and
a progressively higher degree of dealumination with higher
number in the series (Table 1).44 This may account for the
activity of these zeolites in the reaction in question, since the
relatively large pores would allow for diffusion of the relatively
large glycals and reaction products to and from active sites.
The results shown in Table 1 compare reactions at full
completion and hence only reflect the overall activity of the
materials. Additional tests were therefore run with the H-USY
CBV series in order to investigate the difference in initial activity
(Table 2). In a first set of reactions, with a protocol similar to that
of the screening reaction, the catalyst was removed by filtration
after 20 min and conversions could be assessed from 1H-NMR
spectra of the recovered product mixtures. CBV-720 and CBV-
780 showed the highest activity, as determined by % conversion,
but since conversions were still well over 50%, tests were repeated
with the catalyst being removed by filtration after just 10 min.
CBV-720 and CBV-780 again emerged as the most active zeolites.
In the last set of reactions the zeolite was again removed after
10 min but four times as much glucal was used (i.e. 22.5 wt% of
catalyst) and CBV-720 showed the highest initial activity.
In addition, it is known that O-glycosides are more readily
formed in this reaction than other glycosides, and the adequate
nucleophilicity of benzyl alcohol and the ease with which it can
be subsequently removed if desired, suggested this as a good
partner in the initial screening. The results of the screening of
catalysts are summarized in Table 1.
Some zeolites with predominantly Brønsted acidity (H-Beta,
H-BEA-30, Mordenites) and the SAPO-5 material show no
or very low conversion for this reaction. New materials like
the Metal Organic Frameworks (MOFs) with complex acidity
characteristics43 also showed no activity. In contrast, the range
of H-USY zeolites (CBV-series) from CBV-712 to CBV-780 gave
full conversion in acceptable reaction times, combined with high
selectivities and stereoselectivities which are comparable to those
reported for other catalysts. A clear exception was observed
for the H-USY zeolite CBV-600 which only showed moderate
conversion over a long reaction time.
The major difference between the H-USY zeolites and
the proton-containing zeolites (BEA and Mordenites) is the
Table 1 Ferrier rearrangement of acetylated glucal with benzyl alcohol
in the presence of different zeolitesa
Catalyst
SiO2/Al2O3 t/h Conv. (%) Sel. (%) a : b
H-USY CBV-600
H-USY CBV-712
H-USY CBV-720
H-USY CBV-760
H-USY CBV-780
5.2
12
30
60
80
48 30
—
97
97
97
97
—
—
—
—
—
—
—
1
100
6 : 1
7 : 1
6 : 1
7 : 1
—
—
—
—
—
—
0.5 100
1
1
120
48
100
100
—
5
H-Beta (CP811 BC-25) 25
H-BEA 30
30
5.9
11
—
0.1
Mordenite 5.9
Mordenite 11
Cu3(BTC)2 (MOF)
SAPO-5
120
120
150
24
—
—
—
—
Zeolite CBV-720 with the highest initial activity and highest
overall activity was selected for further investigation of optimum
reaction parameters required for the Ferrier rearrangement.
a Conditions: dry zeolite (90 wt%, 0.0612 g), THF (5 ml), acetylated
glucal (0.25 mmol, 0.068 g) and BnOH (36.2 ml, 1.4 eq.). Reaction
progress was monitored by TLC and reactions continued until starting
glycal had been consumed, or no further change in reaction progress
was evident. Conversions, selectivities and a : b ratios are determined
by integration of selected signals in the 1H NMR spectra of product
mixtures.
Optimization of reaction conditions for CBV-720
In the first instance the effect of catalyst pre-treatment was
examined. Samples of CBV-720 zeolite were heated to 400 C
and then either used directly in the reaction, without exposure
to air, or allowed to cool down in ambient air. With the former,
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Table 3 Results obtained for the CBV-720-catalysed Ferrier rearrange-
demonstrated by establishing that after 3 cycles of recovery and
re-calcining of catalyst only minor lowering of the %yield of 2,3-
unsaturated glycosides (to 93%) was observed. THF therefore
appeared to be the optimal solvent for the reaction under the
conditions applied.
ment of acetylated glucal with benzyl alcohol in different solventsa
Solvent
t/h Conv. (%) Sel. (%) a : b Colour of catalyst
CH2Cl2
CH3CN
THF
DMF
EtOAc
Et2O
Acetone
1,4-Dioxane
Nitromethane 72
2
1
100
100
99
99
97
—
99
99
50
99
60
7 : 1 Black
5 : 1 Grey
7 : 1 Light pink
0.33 100
48
—
—
White
Ferrier rearrangement with CBV-720 and various glycals
0.33 100
7.5 : 1 Light grey
7 : 1 White
7 : 1 White
7 : 1 Orange
5 : 1 Dark green
6b
100
100
Using the optimum reaction conditions determined as de-
scribed, the Ferrier rearrangement was then performed on
a range of glycals varying in their relative stereochemistries
(glucal, galactal, xylal) and protecting groups (acetyl, benzyl), in
order to gain insight into stereochemical and stereo-electronic
factors affecting reactivity in presence of the CBV-720 zeolite.
An overview of the results is given in Table 4.
It is clear from our data that compounds carrying acetyl
protecting groups (entries 1, 2 and 3) were much more re-
active and gave significantly better yields than their benzyl-
protected counterparts (entries 4 and 5). This is presumably
due to the acetyl group being a better leaving group in
the allylic rearrangement. With regard to the stereochem-
istry of the substrate, it is evident that glucal and xylal
(entries 1 and 2) have similar reactivity which is significantly
greater than that of galactal (entry 1 vs. entry 3 and entry
4 vs. entry 5). This observation is consistent with earlier
findings.19,34c
The stereochemistry of the products of the Ferrier rearrange-
ment is generally dominated by the anomeric effect resulting in
the preferred formation of a-products. The results in Table 4
show however that the orientation of ring substituents and the
nature of the protecting groups play important roles as well. For
example, acetylated glucal (entry 1) yields predominantly the
a-glycoside while acetylated xylal (entry 2) gives the b-glycoside
as the major product. This suggests an important role for the
substituent at C-5, possibly by restricting the conformational
flexibility of the ring. The role of the protecting group on the
hydroxymethyl group attached to C-5 can be illustrated by
comparing results for the acetylated glucal (entry 1) with the
benzylated glucal (entry 4), with the former giving a poorer
selectivity towards a-glycoside than the latter (6 : 1 vs. 10 : 1).
This could be attributed to the greater steric influence of the
bulky benzyl group in shielding the b-face of the substrate. The
influence of the C-4 substituent is seen when glucal derivatives
(entries 1 and 4) are compared with galactal derivatives (entries
3 and 5). For both acetyl- and benzyl-protected substrates
the stereoselectivity of the reaction is lower for the galactals.
These results are consistent with previous observations, and the
unpredictability of galactal reactivity in the Ferrier reaction has
been noted.19,36b An exceptionally high stereoselectivity (19 : 1)
using phosphomolybdic acid supported on silica gel as catalytic
system37 has been reported, but in our hands afforded an a : b
ratio of only 10 : 1.
2.5
0.33 100
80
a Conditions: dry H-USY CBV-720 (90 wt%, 0.0612 g), solvent (5 ml),
acetylated glucal (0.25 mmol, 0.068 g) and BnOH (36.2 ml, 1.4 eq.).
Reaction progress was monitored by TLC. Conversions, selectivities
and a : b ratios were determined by comparison of integrals of selected
signals in the 1H NMR spectra of the product mixtures. b TLC showed an
estimated 30% conversion after 1.5 h; reaction was complete after 20 h,
but all solvent had evaporated by then and reaction time was estimated
at 6 h.
dry zeolite reaction was complete in only about 20 min, whereas
with the latter the reaction required 36 h. It was thus clear that
drying of the zeolite prior to reaction was essential.
The effect of substrate concentration and catalyst loading
was then investigated. In the screening reactions described
above, 90 wt% of zeolite to substrate was used. In a further
experiment the concentration of glucal was doubled (0.1 M
glucal) resulting in the load of CBV-720 halving to 45 wt%.
In the second reaction the quantity of glycal was doubled again
and the volume of solvent halved (0.4 M glucal) resulting in a
catalyst load of 22.5 wt% zeolite. Full conversion was obtained
after 1 h and 2.5 h respectively, as opposed to 20 min in the
initial experiment. Selectivities and stereoselectivities were not
affected. These results demonstrate that there is no significant
deactivation of the catalyst upon increasing the concentration of
the glycal, and that the zeolite can consequently be used in fairly
small amounts, However, the rate of the reaction is significantly
lowered by reducing the catalyst loading, and further reactions
were therefore carried out at 90 wt% of catalyst to minimize
reaction times.
Attention was then turned to the effect of solvent, bearing
in mind the need to avoid limiting diffusion in zeolite-catalysed
reactions, while also optimizing product selectivities. A range of
solvents with different polarities was tested (Table 3), using the
colour developed by the zeolite in the reaction as a qualitative
measure of pore blocking or deactivation, a darker colour
indicating a larger build-up of carbon deposits which could
hamper recycling.
From the results shown in Table 3 it was evident that
dichloromethane, acetonitrile, DMF, diethyl ether and ni-
tromethane were unsuitable as solvents due to the long re-
action times, deactivation of the zeolite or a combination of
both. Acetone gave good conversions but poor selectivities
towards the Ferrier rearrangement products, even if these were
obtained with reasonable stereoselectivity, 1,4-dioxane, EtOAc
and THF gave comparable reaction times, conversions and
product selectivities, with THF showing the least tendency to
cause discolouration and therefore deactivation of the zeolite.
The effectiveness of zeolite CBV-720 in THF was further
A significant advantage of zeolite CBV-720 is in the superior
reactivity of benzylated glycals (entries 4 and 5). Relatively few
reports have appeared with data on Ferrier rearrangements of
benzylated glycals,3a,21a,21c,39 most of them recording disappoint-
ing yields, whereas the use of H-USY CBV-720 zeolite affords
yields of up to 80% in reasonable reaction times and with good
stereoselectivities.
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Table 4 Results of Ferrier rearrangement of various glycals in the presence of H-USY zeolite CBV-720a
Entry
1
Substrate
Nucleophile
BnOH
t/h
Products
Yield (%)
97
a : b
0.33
7 : 1
2
3
BnOH
BnOH
0.33
1
90
90
1 : 2
3 : 1
4
5
BnOH
BnOH
6
80
80
10 : 1
7 : 1
12
a Conditions: dry H-USY CBV-720 (90 wt%), glycal (0.25 mmol), BnOH (36.2 ml, 1.4 eq.), THF (5 ml), 30 ◦C. Reaction progress was monitored by
TLC. Yield and a : b ratios were determined by comparison of integrals of selected signals in the 1H NMR spectra of the product mixtures
Ferrier rearrangement with different nucleophiles
and nucleophiles to provide efficient access to a range of 2,3-
unsaturated glycosides. The best results were achieved with
acetylated and benzylated glucals with alcoholic nucleophiles,
where conversions and selectivities were similar to the best
reported in the literature. The most notable results are those with
benzylated glucal and galactal, for which significantly higher
yields were achieved than previously described. These results
show the potential for the use of H-USY as a general catalyst
for the Ferrier rearrangement, and extend the scope of these solid
catalysts in organic chemistry in general. The results of this study
indicate that the ideal catalyst for the Ferrier rearrangement
requires an optimal balance of the number and strength of
Brønsted acid sites combined with good accessibility of these
sites, as reflected by their micro- and mesoporosity. Techniques
such as solid state 29Si and 27Al NMR and XPS are being
employed in an ongoing attempt to rationalize these findings.44b
The Ferrier rearrangement was also tested with a range of
nucleophiles other than benzyl alcohol in order to evaluate the
scope for formation of other glycosides. Tri-O-acetyl-D-glucal (1)
was therefore treated with 4-penten-1-ol, thiophenol, allylamine,
benzylamine, trimethylsilyl azide and allyltrimethylsilane in the
presence of CBV-720 under the standard conditions (Table 5,
entries 6–11). Furthermore tri-O-benzyl-D-glucal (7) was tested
with tetradecanol and thiophenol under similar conditions
(Table 5, entries 12 and 13). The results for 1 show the successful
formation of an additional O-glycoside as well as examples of
S-, and C-glycosides, with the attempted preparation of N-
glycosides being unsuccessful. The reaction times and yields
were favourable, and stereoselectivities modest in the S-, and C-
glycosides. The reaction with TMS-azide gave satisfactory con-
version and yield but produced an approximately 1 : 1 mixture
of the C-3 and the C-1 adducts (13a,b and 14a,b). This result is
analogous to that reported by Kawabata et al.18b who could only
overcome this by adding a substituent on the C-2 position, and
has been explained as being a consequence of preference of the
soft azide nucleophile for attack at the softer C-3 electrophilic
centre.45 As found with benzyl alcohol as nucleophile, good
results were obtained with alternative nucleophiles reacting with
tri-O-benzyl-D-glucal. While the less the sterically demanding
tetradecanol gives a lower stereoselectivity (compare entries
4 and 12), the use of thiophenol as a nucleophile afforded
phenylthioglucosides 17a,b in an excellent a : b ratio of 10 : 1.
Experimental
General
Commercially obtained compounds were used as received.
Solvents used were AR grade or dried according to common pro-
cedures. Reaction progress was monitored by TLC. Conversion,
selectivities and a : b ratios were determined by integration of
selected signals from the 1H spectra. NMR spectra were recorded
on a Bruker AMX 300 or a Varian Mercury 300 (300 MHz) and
a Varian Unity 400 (400 MHz).
Substrates
Conclusions
Acetylated glucal was commercially obtained. Benzylated glu-
cal, acetylated and benzylated galactal and acetylated xylal were
synthesized according to literature procedures.
The Ferrier rearrangement has been successfully performed with
a H-USY zeolite CBV-720 as catalyst with a selection of glycals,
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Table 5 Results of the Ferrier rearrangement of acetylated glucal (1) and benzylated glucal (7) with various nucleophiles in the presence of H-USY
zeolite CBV-720a
Entry
1
Glucal
Nucleophile
t/h
Products
Yield (%)
97
a : b
1
Benzyl alcohol
0.33
7 : 1
6
1
4-Penten-1-ol
0.5
95
10 : 1
5 : 3
7
8
1
1
Thiophenol
AzidoTMS
0.75
3
90
80 (13 + 14)
13 : 14 = 1 : 1
13a : 13b = 3 : 2
14a : 14b = 7 : 2
9
1
Allyl TMS
1
70
2 : 1
b
10
11
12
1
1
7
Benzylamine
Allylamine
CH3(CH2)13OH
48
24
7
—
—
—
—
75
—
—
5 : 1
b
13
7
Thiophenol
6
72
10 : 1
a Conditions: dry H-USY CBV-720 (90 wt%, 0.0612 g), 1 (0.25 mmol, 0.068 g), nucleophile (1.4 eq.), THF (5 ml), 30 ◦C. Reaction progress was
1
monitored by TLC. Yield and a : b ratios were determined by comparison of integrals of selected signals in the H NMR spectra of the product
mixtures. b No products detected.
Catalysts
(36.2 ml, 1.4 eq.). The reaction vessel was closed and stirred
at 30 ◦C. On completion of the reaction, as judged by TLC, the
reaction mixture was filtered to remove zeolite and the filtrate
was taken up in DCM, then washed with 1 M NaOH (2 ¥) and
H2O (1 ¥). The organic layer was dried (MgSO4), filtered and
concentrated under reduced pressure. The identity of products
and the ratio of stereoisomers was determined from key signals
in the 1H and 13C NMR spectra, with the aid of COSY, HSQC
and DEPT analysis.
The CBV zeolites (Zeolyst), H-beta CP811-BC25 (Zeolyst), H-
Beta BEA-30 zeolite (Su¨dChemie) and Mordenites were com-
mercially obtained. SAPO-546 and Cu(BTC)3 were prepared
according to previously reported methods. All materials except
Cu2(BTC)3 were dried for 6 h at 400 ◦C (heating rate 1 ◦C min-1)
prior to reaction. Cu2(BTC)3 was dried at 110 ◦C. None of the
materials were allowed to fully cool down before use.
43
Reaction protocols
Reactions with recycled catalyst
Standard reactions. Tri-O-acetyl-D-glucal with benzyl alco-
hol: dry catalyst (61.2 mg) was weighed into a reaction vessel
and solvent (5 ml) was immediately added. Tri-O-acetyl-D-glucal
(68 mg, 0.25 mmol) was added, followed by benzyl alcohol
Reactions were performed with acetylated glucal (1), BnOH
and CBV-720 in THF following the same protocol as described
above. Reaction mixtures were stirred for 2.5 h, then filtered to
◦
recover the zeolite, which was then heated at 10 C min-1 to
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◦
400 C in an oven and left overnight at this temperature prior
4.98–4.92 (m, 1H, H-4), 4.79 (d, J = 11.83 Hz, 1H, OCH2Ph),
4.59 d, J = 11.67 Hz, 1H, OCH2Ph), 4.21 (dd, J = 12.98 and
2.78 Hz, 1H, H-5¢), 3.86 (d, J = 13.12 Hz, 1H, H-5¢), 2.09 (s,
3H, CH3-acetyl); 13C NMR (75 MHz, CDCl3): d 130.8 (C-3),
125.1 (C-2), 92.0 (C-1), 70.6 (CH2Ph), 63.3 (C-4), 61.3 (C-5),
21.1 (OCOCH3).
to use in the next experiment. A sequence of 3 experiments was
performed in this way, giving products 2a,b in yields of 95%,
93% and 93%, respectively.
Other glycals and nucleophiles
Benzyl-4,6-di-O-acetyl-2,3-dideoxy-D-threo-hex-2-
enopyranoside (galacatal) (3)
An analogous protocol to that described above was applied,
using glycal (0.25 mmol), catalyst (90% of mass of glycal) and
nucleophile (0.35 mmol, 1.4 equivalents). For benzylated glucal
the workup consist of washing with H2O (3 ¥), but not with
NaOH.
a: 1H NMR (300 MHz, CDCl3): d 7.4–7.28 (m, 5H, aromatic),
6.3–5.6 (m, 2H, H-2 and H-3), 5.39–5.29 (m, 1H, H-4), 5.10 (d,
J = 2.7 Hz, 1H, H-1), 4.69 (d, J = 11.8 Hz, 1H, OCH2Ph), 4.50
(d, J = 11.8 Hz, 1H, OCH2Ph), 4.30–3.90 (m, 3H, H-5, H-6 and
H-6¢), 2.14 and 2.06 (s, 2 ¥ 3H, CH3-acetyl).
Reactions with higher concentration of glycal
b: 1H NMR (300 MHz, CDCl3): d 7.4–7.28 (m, 5H, aromatic),
6.3–5.6 (m, 2H, H-2 and H-3), 5.39–5.29 (m, 1H, H-4), 5.17 (d,
J = 2.6 Hz, 1H, H-1), 4.82 (d, J = 11.52 Hz, 1H, OCH2Ph),
4.59 (d, J = 11.56 Hz, 1H, OCH2Ph), 4.30–3.90 (m, 3H, H-5,
H-6 and H-6¢), 2.09 and 2.08 (s, 2 ¥ 3H, CH3-acetyl).
45 wt%: analogous protocol as above with dry zeolite CBV-720
(61.2 mg), THF (5 ml), tri-O-acetyl-D-glucal (136 mg, 0.5 mmol)
and benzyl alcohol (72.4 ml).
22.5 wt%: analogous protocol as above with: dry zeolite CBV-
720 (61.2 mg), THF (2.5 ml), tri-O-acetyl-D-glucal (272 mg,
1 mmol) and benzyl alcohol (144.8 ml).
1,4,6-Tri-O-benzyl-2,3-dideoxy-D-erythro-hex-2-enopyranoside
(4)20b,26a
NMR data
a: 1H NMR (300 MHz, CDCl3): d 7.4–7.2 (m, 15H, aromatic),
6.09 (d, J = 10.28 Hz, 1H, H-2), 5.79 (dt, J = 10.16 Hz, 2.25 Hz,
2.5 Hz and 2.16 Hz, 1H, H-3), 5.13 (br s, 1H, H-1), 4.82–4.40
(m, 6H, 3 ¥ OCH2Ph), 4.19 (d, J = 9.41 Hz, 1H), 4.00 (d, J =
10.04 Hz, 1H), 3.73 (dd, J = 10.66 and 3.84 Hz, 1H), 3.63 (dd,
J = 10.56 and 2.0 Hz, 1H); 13C NMR (75 MHz, CDCl3): d
138.2–137.9 and 128.5–127.5 (aromatic), 130.8, 126.5 (C-2 and
C-3), 93.9 (C-1), 73.4, 71.0, 70.0 (3 ¥ OCH2Ph), 70.4, 69.3 (C-4
and C-5), 68.8 (C-6).
Product numbering refers to entries in Table 4 and 5; only
detected signals are reported.
Benzyl-4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-
enopyranoside (1)14,29,36c
1
a: H NMR (400 MHz, CDCl3): d 7.3–7.2 (m, 5H, aromatic),
5.81 (dd, J = 10.38 and 0.95 Hz, 1H, H-3), 5.77 (ddd, J =
10.22, 2.48 and 1.76 Hz, 1H, H-2), 5.25 (ddd, J = 9.33, 2.90
and 1.45 Hz, 1H, H-4), 5.05 (d, J = 1.77 Hz, 1H, H-1), 4.72
(d, J = 11.71 Hz, 1H, OCH2Ph), 4.52 (d, J = 11.71 Hz, 1H,
OCH2Ph), 4.19–4.13 (m, 1H, H-6), 4.10–4.01 (m, 2H, H-5 and
H-6¢), 2.01 and 1.99 (s, 2 ¥ 3H, CH3-acetyl); 13C NMR (100 MHz,
b: 1H NMR (300 MHz, CDCl3): d 6.07 (d, 1H, H-2), 5.88 (dt,
J = 10.03 and 0.86 Hz, 1H, H-3), 5.21 (br s, 1H, H-1).
1,4,6-Tri-O-benzyl-2,3-dideoxy-D-threo-hex-2-enopyranoside
(galacatal) (5)21a
=
CDCl3): d 170.7, 170.2 (3 ¥ C O), 137.6 (aromatic), 129.2 (C-
a: 1H NMR (300 MHz, CDCl3): d 7.4–7.2 (m, 15H, aromatic),
6.12 (dd, J = 10.14 and 5.11 Hz, 1H, H-3), 5.99 (dd, J = 10.09
and 2.93 Hz, 1H, H-2), 5.16 (d, J = 2.77 Hz, 1H, H-1), 4.70–4.40
(m, 6H, OCH2Ph), 4.00–3.60 (m, 4H, H-4, H-5, H-6 and H-6¢).
3), 128.4, 128.0, 127.8, 127.7 (aromatic), 126.9 (C-2), 93.6 (C-1),
70.2 (CH2Ph), 67.1 (C-5), 65.3 (C-4), 62.9 (C-6), 20.9 and 20.7
(2 ¥ OCOCH3).
b: 1H NMR (400 MHz, CDCl3): d 5.92–5.89 (m, 2H, H-2 and
H-3), 5.14–5.11 (m, 2H, H-1 and H-4), 4.80 (d, J = 11.79 Hz,
1H, OCH2Ph), 4.54 (d, J = 11.85 Hz, 1H, OCH2Ph); 13C NMR
(100 MHz, CDCl3): d 130.4 (C-3), 126.0 (C-2), 93.8 (C-1), 72.8
(C-5), 69.4 (CH2Ph), 64.3 (C-4), 63.4 (C-6).
1
b: H NMR (300 MHz, CDCl3): d 6.20 (dd, 1H, H-3), 6.00
(dd, 1H, H-2), 5.21 (dd, 1H, H-1).
Pent-4-enyl-4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-
enopyranoside (6)20c,22
a: 1H NMR (300 MHz, CDCl3): d 5.90–5.76 (m, 3H, H-2,
H-3 and O(CH2)3CH CH2), 5.31 (ddd, J = 9.63, 3.01 and
Benzyl-D-4-O-acetyl-2,3-dideoxypent-2-enoglyceropyranoside
=
(xylal) (2)47
=
1.56 Hz, 1H, H-4), 5.03 (ddd, 1H, OCH2(CH2)2CH CH2), 5.03–
a: 1H NMR (300 MHz, CDCl3): d 7.4–7.25 (m, 5H, aromatic),
6.12–5.85 (m, 2H, H-2 and H-3), 5.35–5.25 (m, 1H, H-4), 5.04
(br s, 1H, H-1), 4.82 (d, J = 11.71 Hz, 1H, OCH2Ph), 4.58 d,
J = 11.71 Hz, 1H, OCH2Ph), 4.00–3.80 (m, 2H, H-5 and H-5¢),
2.07 (s, 3H, CH3-acetyl); 13C NMR (75 MHz, CDCl3): d 129.0
(C-3), 126.9 (C-2), 93.3 (C-1), 69.6 (CH2Ph), 65.0 (C-4), 60.0
(C-5), 21.0 (OCOCH3).
5.00 (m, 1H, H-1), 5.00–4.95 (dtd, 1H, OCH2(CH2)2CH CH2),
=
4.24 (dd, J = 12.16 and 5.38 Hz, 1H, H-6), 4.21–4.14 (dd,
J = 12.06 and 2.45 Hz, 1H, H-6¢), 4.10 (ddd, J = 9.49,
5.43 and 2.46 Hz, 1H, H-5), 3.79 (td, J = 9.63, 6.67 and
=
6.67 Hz, 1H, OCH2(CH2)2CH CH2), 3.52 (td, J = 9.65,
=
6.45 and 6.45 Hz, 1H, OCH2(CH2)2CH CH2), 2.19–2.11
=
(m, 2H, OCH2(CH2)2CH CH2), 2.09 and 2.08 (s, 2 ¥ 3H,
b: 1H NMR (300 MHz, CDCl3): d 7.4–7.25 (m, 5H, aromatic),
6.12–5.85 (m, 2H, H-2 and H-3), 5.10 (d, J = 2.33 Hz, 1H, H-1),
CH3-acetyl), 1.76–1.67 (m, 2H, OCH2(CH2)2CH CH2); 13C
=
=
NMR (75 MHz, CDCl3): d 170.7 and 170.2 (2 ¥ C O),
This journal is
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©

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13
=
=
137.9 (O(CH2)3CH CH2), 129.0 (C-2), 127.8 (C-3), 114.9
C NMR (75 MHz, CDCl3): d 170.1 and 170.3 (2 ¥ C O),
=
=
=
(O(CH2)3CH CH2), 94.4 (C-1), 68.2 (OCH2(CH2)2CH CH2),
133.9, 132.7 and 123.6 (C-2, C-3 and -CH2CH CH2), 117.5 (–
CH2CH CH2), 71.3 (C-1), 69.7 (C-4), 64.9 (C-5), 62.8 (C-6),
37.8 (–CH2CH CH2), 20.6 and 20.8 (2 ¥ OCOCH3).
=
66.9 (C-5), 65.2 (C-4), 63.0 (C-6), 30.3 and 28.9
=
=
(OCH2(CH2)2CH CH2), 20.9 and 20.8 (OCOCH3).
b: 1H NMR (300 MHz, CDCl3):
d
5.21–5.18 (m,
b: 13C NMR (75 MHz, CDCl3): d 170.1 and 170.2 (2 ¥ C O),
=
1H, H-4); 13C NMR (100 MHz, CDCl3): d 170.6 and
133.3, 132.2 and 125.0 (C-2, C-3 and –CH2CH CH2), 117.6 (–
CH2CH CH2), 74.2 (C-1), 74.15 (C-4), 65.5 (C-5), 63.6 (C-6),
39.3 (–CH2CH CH2), 20.6 and 20.8 (2 ¥ OCOCH3).
=
=
=
=
170.2 (2 ¥ C O), 137.9 (O(CH2)3CH CH2), 130.5 (C-2),
126.0 (C-3), 114.8 ((O(CH2)3CH CH2), 95.1 (C-1), 70.6
(OCH2(CH2)2CH CH2), 67.7 (C-5), 64.3 (C-4), 63.4 (C-6), 30.2
and 28.8 (OCH2(CH2)2CH CH2), 20.9, and 20.7 (OCOCH3).
=
=
=
=
Tetradecanyl-4,6-di-O-benzyl-2,3-dideoxy-a-D-erythro-hex-2-
enopyranoside (12)39a
Thiophenyl-4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-
a: 1H NMR (300 MHz, CDCl3): d 7.43–7.22 (m, 10 H, aromatic),
6.06 (d, J = 10.29 Hz, 1H), 5.77 (dt, J = 10.38, 2.43 and 1.99 Hz,
1H, H-2), 5.01 (m, 4H, 2 ¥ OCH2Ph), 4.17 (dd, J = 9.34, 1.00 Hz,
1H, H-4), 3.96 (q, 1H, H-5), 3.81–3.58 (m, 3H, H-6, H-6¢ and
–OCH2–), 3.48 (td, J = 9.53, 6.55 and 6.55 Hz, 1H, –OCH2–
), 1.9–0.5 (m, 27H, aliphatic); 13C NMR (75 MHz, CDCl3): d
138.2 (aromatic) 130.5 (C-3), 128.3, 128.3, 127.8, 127.7 and 127.6
(aromatic), 126.8 (C-2), 94.6 (C-1), 73.3 and 71.0 (OCH2Ph),
70.4 (C-4), 69.1 (C-5), 68.9 (C-6), 68.7 (–OCH2–), 31.9, 29.8,
29.7, 29.4, 29.3 and 22.7 (aliphatic), 14.1 (–CH3).
enopyranoside (7)48
a: 1H NMR (300 MHz, CDCl3); d 7.34–7.26 (m, 5H, aromatic),
6.06 (ddd, J = 10.11, 3.18 and 1.95 Hz, 1H, H-2), 5.86 (td, J =
10.13, 1.73 and 1.73 Hz, 1H, H-3), 5.76 (td, J = 3.56, 1.89 and
1.89 Hz, 1H, H-1), 5.38 (qd, J = 9.54, 2.03, 2.00 and 2.00 Hz, 1H,
H-4), 4.47 (ddd, J = 9.01, 5.87 and 2.55 Hz, 1H, H-5), 4.35–4.19
(m, 2H, H-6 and H-6¢), 2.11 and 2.06 (s, 2 ¥ 3H, CH3-acetyl); 13
C
=
NMR (75 MHz, CDCl3): d 170.7 and 170.3 (2 ¥ C O), 132.7 (C-
2), 131.8 (C-3), 130-127 (5C, aromatic), 83.7 (C-1), 67.3 (C-4),
65.2 (C-5), 63.1 (C-6), 21.0 and 20.7 (OCOCH3).
b: 1H NMR (300 MHz, CDCl3): d 6.03 (d, J = 10.34 Hz, 1H,
H-3), 5.83 (dt, 1H, H-2), 5.10 (d, J = 1.28 Hz, 1H).
1
b: H NMR (300 MHz, CDCl3): d 7.57–7.52, 5.96 (td, J =
10.22, 1.78 and 1.78 Hz, 1H, H-2), 5.81 (td, J = 10.19, 2.43 and
2.43 Hz, 1H, H-3), 5.63 (dd, J = 4.53 and 2.20 Hz, 1H, H-1),
5.25–5.10 (m, 1H, H-4), 4.35–4.19 (m, 2H, H-6 and H-6¢), 3.91
(ddd, J = 7.51, 5.47 and 4.24 Hz, 1H, H-5), 2.09 and 2.06 (s,
2 ¥ 3H, CH3-acetyl); 13C NMR (75 MHz, CDCl3): d 81.4 (C-1),
74.9 (C-4), 64.5 (C-5), 63.3 (C-6), 20.9 and 20.8 (OCOCH3).
Thiophenyl-4,6-di-O-benzyl-2,3-dideoxy-D-erythro-hex-2-
enopyranoside (13)
Yellowish oil, Rf: 0.8 (1 : 9 EtOAc : petroleum ether), HRMS
(EI+): 418.8 m/z.
1
a: H NMR (300 MHz, CDCl3): d 7.57–7.52 (m, 2H, SPh),
3-Azido-4,6-di-O-acetyl-1,2-dideoxy-D-erythro-hex-2-
7.34–7.22 (m, 13H, aromatic), 6.04 (td, J = 10.21, 1.29 and
1.29 Hz, 1H, H-2), 5.98 (ddd, J = 10.19, 2.67 and 1.53 Hz, 1H,
H-3), 5.77 (br s, 1H, H-1), 4.63 (dd, J = 11.82 and 2.51 Hz,
2H, OCH2Ph), 4.49 (dd, J = 11.81, 5.54 Hz, 2H, OCH2Ph),
4.33 (ddd, J = 9.28, 3.91 and 2.55 Hz, 1H, H-5), 4.24 (ddd, J =
9.27, 3.30 and 1.56 Hz, 1H, H-4), 3.79–3.76 (m, 2H, H-6 and
H-6¢); 13C NMR (75 MHz, CDCl3): d 131.6 (1C, SPh), 129.1
(C-2), 127.2 (C-3), 129.0-127.3 (17C, aromatic), 84.1 (C-1), 73.3
(CH2Ph), 71.2 (CH2Ph), 70.3 (C-4), 69.7 (C-5), 69.0 (C-6).
b: 1H NMR (300 MHz, CDCl3): d 5.87 (td, J = 2.68, 1.66 and
1.66 Hz, 1H, H-2), 5.81-5.77 (m, 1H, H-3), 5.64 (q, J = 2.15,
2.13 and 2.13 Hz, 1H, H-1); 13C NMR (75 MHz, CDCl3): d 81.1
(C-1), 71.8 (CH2Ph), 71.0 (CH2Ph).
enopyranoside (8A)49
1
a: H NMR (300 MHz, CDCl3): d 6.53 (d, J = 5.96 Hz, 1H,
H-1), 5.10 (dd, J = 10.51 and 4.33 Hz, 1H), 4.90 (t, J = 5.86 Hz,
1H), 2.09 and 2.15 (s, 2 ¥ 3H, CH3-acetyl); 13C NMR (75 MHz,
=
CDCl3): d 170.5 and 169.6 (2 ¥ C O), 146.9 (C-1), 96.4 (C-2),
68.0 (C-4 or C-5), 61.8 (C-6), 53.3 (C-3).
b: 13C NMR (75 MHz, CDCl3): d 98.1 (C-2), 53.4 (C-3).
1-Azido-4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-
enopyranoside (8B)49
a: 1H NMR (300 MHz, CDCl3): d 5.96 (dt, J = 10.19 Hz, 1H,
H-2 or H-3), 5.78 (dt, 1H, H-2 or H-3), 5.57 (br s, 1H, H-1),
5.36–5.33 (m, 1H, H-4), 4.43-4.05 (m, 3H, H-5, H-6 and H-
6¢), 2.11 and 2.12 (s, 2 ¥ 3H, CH3-acetyl); 13C NMR (75 MHz,
CDCl3): d 129.6 (C-2 or C-3), 126.3 (C-2 or C-3), 68.8 (C-4 or
C-5), 64.5 (C-4 or C-5), 62.5 (C-6), 57.6 (C-1).
b: 1H NMR (300 MHz, CDCl3): d 6.05 (ddd, 1H, H-2 or H-3),
5.86 (dt, 1H, H-2 or H-3); 13C NMR (75 MHz, CDCl3): d 128.5
(C-2 or C-3), 128.0 (C-2 or C-3).
Acknowledgements
This research is supported by the National Research Foundation
(South Africa) and the Flemish Government (Bilateral Scientific
Cooperation). The authors further like to thank Methusalem,
for long term financing of the Flemish government, IAP (Belgian
Federal Government) and the Claude Leon Foundation for
funding.
Allyl-4,6-di-O-acetyl-2,3-dideoxy-D-erythro-hex-2-
enopyranoside (9)4,12,18c
Notes and references
1
a: H NMR (300 MHz, CDCl3); d 6.06–5.60 (m, 3H, H-2, H-
3 and –CH2CH CH2), 5.35–5.20 (m, 1H, H-4), 5.18–5.05 (m,
2H, -CH2CH CH2), 4.35–4.05 (m, 3H, H-1, H-6 and H-6¢),
4.01–3.92 (m, 1H, H-5), 2.54–2.25 (m, 2H, –CH2CH CH2);
1 R. J. Ferrier and N. Prasad, J. Chem. Soc. C, 1969, 570.
=
2 (a) S. J. Danishefsky and M. T. Bilodeau, Angew. Chem., Int. Ed.
Engl., 1996, 35, 1380; (b) B. Fraser-Reid, Acc. Chem. Res., 1985,
18, 347; (c) N. R. Williams and J. D. Wander, The Carbohydrates
=
=
834 | Green Chem., 2010, 12, 828–835
This journal is
The Royal Society of Chemistry 2010
©

View Article Online
in Chemistry and Biochemistry, Academic Press, New York, 1980, p
761.
31 N. Suryakiran, S. M. Reddy, M. Srinivasulu and Y. Venkateswarlu,
Synth. Commun., 2008, 38, 170.
32 M. Tingoli, B. Panunzi and F. Santacroce, Tetrahedron Lett., 1999,
40, 9329.
33 K. Toshima, T. Ishizuka, G. Matsuo, M. Nakata and M. Kinoshita,
J. Chem. Soc., Chem. Commun., 1993, 704.
34 (a) R. N. de Oliveira, J. R. d. F. Filho and R. M. Srivastava,
Tetrahedron Lett., 2002, 43, 2141; (b) K. Toshima, N. Miyamoto, G.
Matsuo, M. Nakata and S. Matsumura, Chem. Commun., 1996, 1379;
(c) B. Shanmugasundaram, A. K. Bose and K. K. Balasubramanian,
Tetrahedron Lett., 2002, 43, 6795.
35 Wenting Du and Yongzhou Hu, Synth. Commun., 2006, 36, 2035.
36 (a) A. Agarwal, S. Rani and Y. D. Vankar, J. Org. Chem., 2004, 69,
6137; (b) P. Tiwari, G. Agnihotri and A. K. Misra, Carbohydr. Res.,
2005, 340, 749; (c) A. K. Misra, P. Tiwari and G. Agnihotri, Synthesis,
2005, 260.
37 J. S. Yadav, M. Satyanarayana, E. Balanarsaiah and S. Raghavendra,
Tetrahedron Lett., 2006, 47, 6095.
3 (a) B. Sobhana Babu and K. Kuppuswamy Balasubramanian,
Tetrahedron Lett., 2000, 41, 1271; (b) S. K. Das, K. A. Reddy,
C. Abbineni, J. Roy, K. V. L. N. Rao, R. H. Sachwani and J.
Iqbal, Tetrahedron Lett., 2003, 44, 4507; (c) S. B. Boga and K. K.
Balasubramanian, Arkivoc, 2004, 87; (d) R. Ghosh, A. Chakraborty
and S. Maiti, Arkivoc, 2004, 1.
4 N. Swamy, M. Srinivasulu, T. S. Reddy, T. V. Goud and Y.
Venkateswarlu, J. Carbohydr. Chem., 2004, 23, 435.
5 S. Kashyap and S. Hotha, Tetrahedron Lett., 2006, 47, 2021.
6 S. Danishefsky and J. F. Kerwin, J. Org. Chem., 1982, 47, 3803.
7 S. Hotha and A. Tripathi, Tetrahedron Lett., 2005, 46, 4555.
8 B. K. Bettadaiah and P. Srinivas, Tetrahedron Lett., 2003, 44, 7257.
9 R. D. Tilve, M. V. Alexander, A. C. Khandekar, S. D. Samant and
V. R. Kanetkar, J. Mol. Catal. A: Chem., 2004, 223, 237.
10 J. S. Yadav, B. V. S. Reddy, K. B. Reddy and M. Satyanarayana,
Tetrahedron Lett., 2002, 43, 7009.
11 N. R. Swamy and Y. Venkateswarlu, Synthesis, 2002, 598.
12 J. S. Yadav and B. V. S. Reddy, Synthesis, 2002, 511.
13 J. S. Yadav, B. V. S. Reddy, L. Chandraiah and K. S. Reddy,
Carbohydr. Res., 2001, 332, 221.
14 J. S. Yadav, B. V. S. Reddy and J. S. S. Reddy, J. Chem. Soc., Perkin
Trans. 1, 2002, 2390.
15 A. Procopio, R. Dalpozzo, A. De Nino, L. Maiuolo, M. Nardi, M.
Oliverio and B. Russo, Carbohydr. Res., 2007, 342, 2125.
16 R. Ghosh, A. Chakraborty and D. K. Maiti, Synth. Commun., 2003,
33, 1623.
17 J. S. Yadav, B. V. S. Reddy and P. K. Chand, Tetrahedron Lett., 2001,
42, 4057.
18 (a) M. Takhi, A. A.-H. Abdel-Rahman and R. R. Schmidt, Tetrahe-
dron Lett., 2001, 42, 4053; (b) H. Kawabata, S. Kubo and M. Hayashi,
Carbohydr. Res., 2001, 333, 153; (c) S. Anjaiah, S. Chandrasekhar and
R. Gre´e, J. Mol. Catal. A: Chem., 2004, 214, 133.
19 A. A.-H. Abdel-Rahman, G. A. Winterfeld, M. Takhi and R. R.
Schmidt, Eur. J. Org. Chem., 2002, 713.
38 Qiang Tian, Xing-Mei Zhu and Jin-Song Yang, Synth. Commun.,
2007, 37, 691.
39 (a) A. P. Rauter, T. Almeida, A. I. Vicente, V. Ribeiro, J. C. Bordado,
J. P. Marques, F. R. Ribeiro, M. J. Ferreira, C. Oliveira and M.
Guisnet, Eur. J. Org. Chem., 2006, 2429; (b) A. P. Rauter, T. Almeida,
N. M. Xavier, F. Siopa, A. I. Vicente, S. D. Lucas, J. P. Marques,
F. Ramoˆa Ribeiro, M. Guisnet and M. J. Ferreira, J. Mol. Catal. A:
Chem., 2007, 275, 206.
40 (a) D. E. De Vos, M. Dams, B. F. Sels and P. A. Jacobs, Chem. Rev.,
2002, 102, 3615;(b) D. E. De Vos and P. A. Jacobs, in Catalytic Science
Series-Vol. 3, Zeolites for Cleaner Technologies, ed. Michel Guisnet
and Jean-Pierre Gilson, Imperial College Press, London, 2002, pp.
261–280; (c) A. Corma and H. Garcia, Catal. Today, 1997, 38, 257–
308; (d) P. B. Venuto, in Studies in Surface Science and Catalysis, ed.
Hakze Chon, Son Kilhm and Young Sun Uh, Elsevier, Amsterdam,
1997, pp. 811–852.
41 N. M. Xavier, S. D. Lucas and A. P. Rauter, J. Mol. Catal. A: Chem.,
2009, 305, 84–89.
20 (a) L. V. Dunkerton, N. K. Adair, J. M. Euske, K. T. Brady and
P. D. Robinson, J. Org. Chem., 1988, 53, 845; (b) E. Wieczorek and
J. Thiem, Carbohydr. Res., 1998, 307, 263; (c) S. Konstantinovic, J.
Predojevic, S. Gojkovic and V. Pavlovic, J. Serb. Chem. Soc., 2001,
66, 73.
21 (a) K. Pachamuthu and Y. D. Vankar, J. Org. Chem., 2001, 66, 7511;
(b) J. S. Yadav, V. B. S. Reddy and S. K. Pandey, New J. Chem., 2001,
25, 538; (c) S. Paul and N. Jayaraman, Carbohydr. Res., 2004, 339,
2197.
42 (a) D. W. Gammon, H. H. Kinfe, D. E. De Vos, P. A. Jacobs and B. F.
Sels, Tetrahedron Lett., 2004, 45, 9533; (b) B. Sels, P. Levecque, R.
Brosius, D. E. De Vos, P. A. Jacobs, D. W. Gammon and H. H. Kinfe,
Adv. Synth. Catal., 2005, 347, 93; (c) P. Levecque, D. Gammon, H. H.
Kinfe, P. Jacobs, D. De Vos and B. Sels, Org. Biomol. Chem., 2007,
5, 1800; (d) D. W. Gammon, H. H. Kinfe, D. E. De Vos, P. A. Jacobs
and B. F. Sels, J. Carbohydr. Chem., 2007, 26, 141; (e) P. Levecque,
D. W. Gammon, H. H. Kinfe, P. Jacobs, D. De Vos and B. Sels,
Adv. Synth. Catal., 2008, 350, 1557; (f) D. W. Gammon and B. F.
Sels, in Handbook of Chemical Glycosylation, ed. A. V. Demchenko,
Wiley-VCH, Weinheim, 2008, pp. 416–448.
22 J. Cristobal Lopez, A. M. Gomez, S. Valverde and B. Fraser-Reid,
J. Org. Chem., 1995, 60, 3851.
23 S. Xue, L. He, K. Han, X. Zheng and Q. Guo, Carbohydr. Res., 2005,
340, 303.
24 S. Price, S. Edwards, T. Wu and T. Minehan, Tetrahedron Lett., 2004,
45, 5197.
25 S. Chandrasekhar, C. R. Reddy and G. Chandrashekar, Tetrahedron
Lett., 2004, 45, 6481.
43 L. Alaerts, E. Se´guin, H. Poelman, F. Thibault-Starzyk, P. A. Jacobs
and D. E. D. Vos, Chem.–Eur. J., 2006, 12, 7353.
44 (a) R. A. Beyerlein, C. ChoiFeng, J. B. Hall, B. J. Huggins and G. J.
Ray, Top. Catal., 1997, 4, 27; (b) M. J. Remy, D. Stanica, G. Poncelet,
E. J. P. Feijen, P. J. Grobet, J. A. Martens and P. A. Jacobs, J. Phys.
Chem., 1996, 100, 12440.
26 (a) H. Kim, H. Men and C. Lee, J. Am. Chem. Soc., 2004, 126, 1336;
(b) N. de la Figuera, P. Forns, J. Ferna`ndez, S. Fiol, D. Ferna´ndez-
Forner and F. Albericio, Tetrahedron Lett., 2005, 46, 7271.
27 E. Rafiee, S. Tangestaninejad, M. H. Habibi and V. Mirkhani, Bioorg.
Med. Chem. Lett., 2004, 14, 3611.
28 G. Zhang, Q. Liu, L. Shi and J. Wang, Tetrahedron, 2008, 64, 339.
29 P. U. Naik, S. J. Nara, J. R. Harjani and M. M. Salunkhe, J. Mol.
Catal. A: Chem., 2005, 234, 35.
45 W. Priebe and A. Zamojski, Tetrahedron, 1980, 36, 287–297.
46 (a) B. M. Lok, C. A. Messina, R. L. Patton, R. T. Gajek, T. R. Cannan
and E. M. Flanigen, J. Am. Chem. Soc., 1984, 106, 6092; (b) B. M.
Lok, C. A. Messina, R. L. Patton, R. T. Gajek, T. R. Cannan and
E. M. Flanigen, US Pat., 4440871, 1984.
47 C. Fava, R. Galeazzi, G. Mobbili and M. Orena, Tetrahedron:
Asymmetry, 2001, 12, 2731–2741.
48 A. de Raadt and R. J. Ferrier, Carbohydr. Res., 1992, 216, 93–
30 B. K. Banik, D. Adler, P. Nguyen and N. Srivastava, Heterocycles,
2003, 61, 101.
107.
49 M. Koreeda and T. A. Houston, World Pat., 94/07900, 1994.
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