Efficient activation of thioglycosides with N-(p-methylphenylthio) - Caprolactam-TMSOTf

Article abstract of DOI:10.1016/j.carres.2012.03.024

N-(p-Methylphenylthio) - caprolactam (1) in combination with trimethylsilyl trifluoromethanesulfonate (TMSOTf) provides an efficient thiophilic promoter system, capable of activating different thioglycosides. Both 'armed' and 'disarmed' thioglycosyl donor

Full text of DOI:10.1016/j.carres.2012.03.024

Carbohydrate Research 354 (2012) 40–48
Contents lists available at SciVerse ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Efficient activation of thioglycosides with N-(p-methylphenylthio)-e-caprolac-
tam-TMSOTf
⇑
Sajal Kumar Maity, Nabamita Basu, Rina Ghosh
Department of Chemistry, Jadavpur University, Kolkata 700 032, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 January 2012
Received in revised form 17 March 2012
Accepted 22 March 2012
Available online 7 April 2012
O
STol
OBn
O
H3C
BnO
S
N
OBz
O
OBn
1
CH3
H3C
O
STol
Keywords:
Glycosylation
BzO
OBn
BzO
TMSOTf
CH2Cl2
O
N-(p-Methylphenylthio)-
TMSOTf
e-caprolactam
OBz
OBn
90%
O
BnO
HO
STol
Thioglycoside
BzO
OBz
N-(p-Methylphenylthio)-e-caprolactam (1) in combination with trimethylsilyl trifluorometh-
anesulfonate (TMSOTf) provides an efficient thiophilic promoter system, capable of activating
different thioglycosides. Both ‘armed’ and ‘disarmed’ thioglycosyl donors were activated for gly-
cosidic bond formation. Notably, this reagent combination works well in reactivity-based one-
pot oligosaccharide assembly strategy.
Ó 2012 Elsevier Ltd. All rights reserved.
1. Introduction
tion of oligosaccharides in greatly simplified manner and also for
the assembly of oligosaccharide library.
Owing to the multifaceted biological significance and remark-
able therapeutic potential of complex oligosaccharides and glyco-
conjugates in life processes,1 the synthesis of oligosaccharides
has been the subject of research for many years. Glycosylation
method is considered to be the most crucial step for the synthesis
of oligosaccharides and glycoconjugates.2 In spite of many reports
on glycosylations3 since several of them are not devoid of limita-
tions toward synthesis of oligosaccharides, development of a gen-
eral, convenient, and efficient methodology for the assembly of a
variety of oligosaccharides is still desirable.
Among the various classes of glycosyl donors, thioglycosides
have several advantages4 like their stability and accessibility.
Moreover, these are compatible with many protection and depro-
tection sequences and thus can be used for the preparation of
various glycosyl donors and glycosyl acceptors.4,5 These versatile
features of thioglycosides allow them to be used for the prepara-
So far there are many promoter systems available for the activa-
tion of thioglycosides toward glycosylation. The widely-used pro-
moters for thioglycoside activation include NIS/TfOH,6 DMTST,7
IDCP,8 MeOTf,9 MeSOTf,10 PhSeOTf,11 and its related sulfur analog.12
Sulfinamide-type activators in combination with Lewis acids such
13
as EtSNphth-TrB(C6F5)4
and N-(phenylthio)-e-caprolactam-
Tf2O14 systems have also been described. Recently various kinds
of organosulfur reagents, which include S-(4-methoxyphenyl)
benzenethiosulfinates,15 BSP/Tf2O,16 DPSO/Tf2O,17 BSM/Tf2O,18
Me2S2/Tf2O,19 BDMS/AgOTf20 and DMTPSB/AgOTf21 have been
utilized for glycosylation. It is known that benzenesulfinyl or benze-
nesulfenyl derived promoter systems are an extremely powerful
thiophilic reagent that can be used to couple thioglycosides with
various acceptors at low temperature only. While available promot-
ers are convenient to construct oligosaccharides, but, numerous
drawbacks and limitations have also been noticed which mainly in-
cludes reagent stability, solubility, and most importantly, side reac-
tions with by-products resulting from the promoters.18,22 These
issues prompted us to search for a more convenient and powerful
⇑
Corresponding author. Fax: +91 033 2414 6266.
E-mail addresses: ghoshrina@yahoo.com, ghosh_rina@hotmail.com (R. Ghosh).
0008-6215/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.carres.2012.03.024

S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
41
TMS
CH3
OTf
O
S
OTf
CH2Cl2
CH3
S
STol
OBn
STol
N
O
O
H3C
BnO
H3C
BnO
OBn
OBn
OBn
2
3
4
TMS
O
O
N
9
S
TolS STol
N
TMSOTf
CH3
5
1
OBz
O
HO
BzO
OBz
O
OTf
O
BzO
7
OMe
H3C
BnO
O
OBn
BzO
OBn
OBn
BzO
OMe
O
H3C
BnO
6
OBn
8
Scheme 1. Plausible mechanism for thioglycoside activation.
Table 1
Screening of the reaction conditions for the synthesis of 8
That the reaction does not proceed via activation of the thiogly-
coside donor with pTolSOTf formed (if any) in situ from the reac-
tion of 1 with TMSOTf is evidenced from the following sets of
experiments. The glycosyl donor 10 in reaction (following the con-
dition reported by Yamago et al.25) with pTolSCl and AgOTf at
ꢀ60 °C got activated within 5 min, which then on treatment with
the glycosyl acceptor 11 at ꢀ60 °C followed by increasing the tem-
perature to 25 °C resulted in the formation of the corresponding
disaccharide 1226 (Fig. 1). When 10 was treated with a mixture
of 1 and TMSOTf at ꢀ60 °C, and then the mixture was subjected
to react with 11, after increasing the temperature to 25 °C, 10 re-
mained intact and could be recovered in 98% yield from the reac-
tion mixture even after 24 h, but, the glycosyl acceptor 11 was
fully consumed producing a mixture of self coupled products.
Si of TMSOTf being a soft center is likely to react preferentially
with the softer amide carbonyl O rather than the hydroxyl O of the
glycosyl acceptor. Thus, we propose that, N-(p-methylphenylthio)-
Entry
Promoter system
Yielda/yieldb
1
2
3
4
5
N-(p-Methylphenylthio)-
N-(p-Methylphenylthio)-
N-(p-Methylphenylthio)-
TMSOTf
e
e
e
-caprolactam
-caprolactam/Tf2O
-caprolactam/TMSOTf
—
90%/85%
92%/89%
—/<5%
90%/84%
N-(Phenylthio)-e-caprolactam/Tf2O
a
Condition: 1.1:1.0:1.1 donor/acceptor/promoter, ꢀ45 °C to ambient
temperature, 30 min.
b
Condition: 1.1:1.0:1.1 donor/acceptor/promoter, room temperature, 15 min. All
reactions were carried out in CH2Cl2.
promoter system for the activation of thioglycosides that will
reduce the existing problem associated with glycosylation reactions
as well as can also be used in one-pot oligosaccharide assembly.
N-(p-Methylphenylthio)-e-caprolactam (1), a white crystalline,
easy to prepare, cost effective, and new shelf-stable compound, is
a convenient ‘soft’ electrophilic reagent. In continuation of our
research on carbohydrates23 including oligosaccharide syntheses,24
we report herein, 1 with TMSOTf as a new promoter system for the
activation of thioglycosides and its application in the reactivity-
based one-pot oligosaccharide synthesis.
e-caprolactam (1) may react with TMSOTf to provide a strong
electrophilic reagent 3, which is then exposed to be attacked by
the ‘soft’ nucleophile 2, producing activated sugar derived complex
4. The activated species may then liberate disulfide 5 to produce
oxacarbenium ion intermediate 6, which then reacts with acceptor
7, yielding the desired disaccharide 8 in 92% yield (Scheme 1).
Under the present activation condition a variety of glycosyl do-
nors and acceptors were employed to evaluate the efficacy and
scope of this promoter system (Table 2). The glycosylations of dif-
ferent ‘armed’ thioglycosides with various glycosyl acceptors, hav-
ing a secondary hydroxyl group exposed proceeded smoothly
(Table 2, entries 1–5). As shown, the ‘armed’ thioglycoside 13 acti-
vated by 1-TMSOTf, reacted readily with the glucoside acceptor 7,
affording the desired disaccharide 14 in high yield (entry 2). The
other ‘armed’ thioglycoside donors, such as 15 (entry 3) and 17
(entry 4), were also activated quickly and efficiently at low-tem-
perature, and the coupling products were obtained in high yields.
The latter entry also demonstrates the compatibility with several
protecting groups including TBDPS, benzyl, and acyl. As shown, a
number of 4-O-linked disaccharides, which suffered from side
2. Results and discussion
At the outset, to test the activating capability of 1 in conjugation
with TMSOTf, the glycosylation reaction of benzylated thioglycoside
donor 2 with glucoside acceptor 7 was investigated (Scheme 1).
Through a preliminary screening of reactions (Table 1), we found
that 1 in combination with TMSOTf furnished the best result
(performing the reaction in CH2Cl2 at ꢀ45 °C to ambient tempera-
ture, entry 3, Table 1). Thus, 1—TMSOTf combo system was able to
activate glycosyl donor 2 even at low temperature. It is worthy to
mention here that the use of sub-stoichiometric amount of TMSOTf
in the combo reagent system resulted in incomplete conversion of
the starting materials.
OBn
O
OAc
O
OAc
O
OBn
O
HO
AcO
AcO
AcO
AcO
STol
STol
O
STol
AcO
AcO
NPhth
11
NPhth
10
NPhth
12
NPhth
Figure 1.

42
S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
Table 2
Glycosylations with N-(p-methylphenylthio)-
e
-caprolactam (1) and trimethylsilyl trifluoromethane sulfonatea
Entry
Glycosyl donor
Glycosyl acceptor
Product
Yieldb (%)
92
STol
OBz
OBz
O
O
H3C
BnO
OBn
O
HO
OBn
2
O
BzO
BzO
BzO
BzO
1
OMe
OMe
O
H3C
BnO
OBn
7
8
OBn
BnO
BnO
OBz
O
BnO
OBn
OBn
O
O
HO
STol
BzO
BnO
OBz
O
BzO
7
BnO
BnO
13
2
3
4
90
89
91
OMe
O
BzO
14
BzO
OMe
Ph
OBz
O
Ph
HO
O
O
BzO
O
O
BzO
7
O
O
OMe
STol
BnO
BnO
OBz
O
BnO
15
BnO
O
BzO
BzO
16
OMe
AcO
BnO
OBz
O
AcO
BnO
OTBDPS
O
OTBDPS
O
HO
STol
BzO
OBz
O
BzO
7
BnO
17
BnO
OMe
O
BzO
BzO
OMe
18
OAc
OBn
OAc
O
BnO
BnO
BnO
BnO
BnO
BnO
OBn
O
OBn
OBn
O
HO
BnO
5
6
95
88
O
SPh
O
19
OMe
BnO
20
21
OMe
HO
BzO
BzO
Ph
O
O
Ph
O
O
O
O
O
O
SEt
BnO
BnO
BzO
AcO
22
AcO
O
BzO
OMe
23
BzO
24
BzO
OMe
BzO
BzO
HO
BzO
BzO
OBz
O
OBz
O
BzO
BzO
O
O
STol
BzO
7
8
9
95
93
95
OMe
OBz
BzO
OBz
O
23
25
BzO
26
BzO
OMe
BzO
BnO
HO
OBn
BzO
OBz
O
OBz
OBn
O
BnO
O
O
O
STol
STol
STol
BnO
BzO
BzO
BnO
OBz
OBz
OMe
20
27
OMe
25
OAc
O
HO
BzO
BzO
OAc
O
O
O
AcO
AcO
AcO
AcO
BzO
NPhth
10
NPhth
OMe
O
23
BzO
BzO
BzO
28
OMe
OBz
O
OBz
O
O
H3C
BnO
OBn
HO
STol
STol
STol
OBn
O
BzO
BzO
OBn
10
11
90
93
2
OBz
OBz
O
H3C
BnO
29
30
OBn
BnO
BnO
OBz
O
BnO
OBn
O
OBn
O
HO
STol
BzO
BnO
OBz
O
BnO
13
BnO
OBz
29
O
STol
BzO
OBz
31
OAc
O
OBz
OAc
BnO
BnO
BnO
HO
BnO
BnO
BnO
O
O
BzO
BzO
OBz
12
13
94
87
32
SPh
O
19 SPh
O
BzO
BzO
33
SPh
Ph
HO
BzO
BzO
Ph
O
STol
O
O
O
O
OBz
O
O
35
STol
O
BzO
BzO
BzO
34
BzO
BzO
O
STol
BzO
OBz
36
a
All reactions were carried out in CH2Cl2.
Isolated yield.
b

S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
43
OBn
O
OBz
O
OBn
O
1,
TMSOTf
HO
HO
BzO
BnO
BnO
STol
STol
+
BnO
BnO
OBn
O
BnO
OBn
O
OBz
BnO
OBn
29
OMe
37
38
STol
BnO
OBz
O
BnO
BnO
1, TMSOTf
OBn
O
OBn
O
STol
13
CH2Cl2
BzO
BnO
BnO
OBz
OBn
O
OBn
OBn
OBn
O
BnO
O
BnO
O
O
O
HO
BnO
BnO
BnO
+
BnO
BnO
OBn
BnO
OMe
BnO
BnO
BnO
OBn
O
OMe
OMe
39
38
40
OBz
O
OBn
1, TMSOTf
BnO
O
O
O
isolated yield
BzO
BnO
entry
solvent
CH2Cl2
BzO
BnO
39
45%
72%
MeCN-CH2Cl2 21%
40
42%
OMe
43
65 %
1
Et2O-CH2Cl2
2
19%
Scheme 4. Reactivity-based one-pot glycosylation of 43.
68%
3
Scheme 2. Solvent effects on the stereoselectivity of glycosylations.
As a final demonstration of the reagent combination, we apply
this in the reactivity-based one-pot synthesis of oligosaccharide.
A one-pot synthesis of a trisaccharide derivative, 43 as outlined in
Scheme 4, was carried out in satisfactory yield and with good stere-
oselectivity, supporting that this new reagent combination can be
used in reactivity-based one-pot assembly of oligosaccharides.
OAc
O
OH
O
AcO
AcO
HO
STol
+
BnO
NPhth
10
BnO
OMe
41
1,
TMSOTf
CH2Cl2
3. Conclusion
81 %
O
AcO
In summary, the combination of a cost-effective and stable thio-
philic reagent [N-(p-methylphenylthio)-e-caprolactam] and TMSOTf
O
AcO
AcO
AcO
AcO
AcO
NPhth
works as an efficient promoter system for the activation of thiogly-
cosides toward glycosylation reactions. Both ‘disarmed’ and ‘armed’
glycosyl donors can be triggered smoothly at low-temperature, and
the coupling reactions proceed very well with a variety of glycosyl
acceptors in high yields. This reagent overcomes limitations of some
reported methods and can be employed in the reactivity-based one-
pot oligosaccharide assembly.
O
O
O
BnO
NPhth
BnO
OMe
42
Scheme 3. Double glycosylation.
products at the glycosylation step when promoted by NIS-TfOH22a
using ‘armed’ thioglycoside donors were prepared in high yields
when relatively low reactive acceptor 7 was used.
It is noteworthy that, the ‘disarmed’ thioglycosides also reacted
very easily and efficiently. As shown, the ‘disarmed’ thioglycosides
25 activated by 1-TMSOTf, reacted readily with the acceptor 23,
affording the desired disaccharide in high yield (Table 2, entry 7).
The low-reactive benzoyl-protected acceptor 2321 also coupled
smoothly with 10 to obtain disaccharide 28 in 95% isolated yield
(entry 9). In all cases, the ‘disarmed’ thioglycosides in Table 2,
invariably afforded 1,2-trans-linked disaccharides as a result of
neighboring group participation; no orthoesters were detected.
In a different experiment, the solvent effects on the stereoselec-
tivity of glycosylation were also examined. A high combined yield
but low stereoselectivity was observed when perbenzylated thiog-
lucoside 37, was reacted with 38 in dichloromethane affording the
corresponding anomeric mixture of 39 and 40 (Scheme 2). The
4. Experimental section
4.1. General
All reactions were performed in flame-dried flasks fitted with
rubber septa under a positive pressure of argon, unless otherwise
stated. Dichloromethane was refluxed with P2O5 and distilled be-
fore use. Diethyl ether (Merck, India) and acetonitrile (Merck, In-
dia) were distilled over P2O5, and stored over 4 Å molecular
sieves before use. Trimethylsilyl trifluroromethanesulfonate was
purchased from Aldrich and used without further purification. Tri-
ethylamine was purchased from Merck (India) and distilled over
potassium hydroxide before use. N-(p-Methylthiophenyl)-e-capro-
lactam (1) was synthesized. Traces of water in the donor and
acceptor glycosides were removed by co-evaporation with toluene.
Molecular sieves (4 Å) were flame dried before use. Flash column
chromatography was performed employing Silica Gel 60 Sorbent
selectivity could be shifted significantly toward the
a-anomer by
using ether or toward the b-anomer by using acetonitrile as cosol-
vent. This can be explained by the participation of the solvents.27
Next, we apply this reagent combination in a reactivity-based
oligosaccharide synthesis. In fact, this reagent combination works
well, as we were able to synthesize various disaccharides using
thioglycosides as acceptors in excellent yields (Table 2, entries
10–13). Disaccharide 31, which suffered from by-products when
using NIS/TfOH as promoter,22a was also obtained in high yield.
To investigate the power of the new reagent combination, we
turned to the double glycosylation of carbohydrate diols. Union
of a 4,6-glucopyranosyl diol 41 and phthalimide protected glucosa-
mine donor 10, resulted in the isolation of the desired trisaccharide
42 in 81% yield (Scheme 3).
(40–63 lm, 230–400 mesh). Thin-layer chromatography (analyti-
cal and preparative) was performed using Merck silica gel plates
(60-F254) to monitor the reactions and visualized under UV
(254 nm) and/or by charring with 5% ethanolic solution of sulfuric
acid. 1H and 13C NMR spectra were recorded on a Bruker DPX-300
(300 MHz),
a Bruker DPX-400 (400 MHz), a Bruker DPX-500
(500 MHz), or a Bruker DPX-600 (600 MHz) spectrometer at ambi-
ent temperature in CDCl3, and assigned using 2D-methods (COSY,
HSQC). Chemical shifts were expressed in parts per million (d
scale). Optical rotations were measured using Jasco P-1020 digital
polarimeter. High Resolution Mass Spectra (HRMS) were measured

44
S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
in a QTOF I (quadrupole-hexapole-TOF) mass spectrometer with an
orthogonal Z-spray-electrospray interface on Micro (YA-263) mass
spectrometer (Manchester, UK).
warmed gradually to ambient temperature over 30 min. The reac-
tion was then quenched with Et3N (180 L), filtered off through a
l
pad of Celite, and concentrated. The crude residue was directly
purified by silica gel flash column chromatography (hexane/EtOAc,
6:1) to afford 1414 (72.9 mg, 90%) as a white foam. Rf 0.22 (20%
4.2. Preparation of N-(p-methylphenylthio)-e-caprolactam (1)
EtOAc in hexane); ½a D24
ꢂ
+79.2 (c 1.0, CHCl3); 1H NMR (500 MHz,
A solution of freshly prepared p-toluenesulfenyl chloride12
(5.0 g, 31.6 mmol), in CCl4 (20 mL) was added drop wise with stir-
ring, at 0–5 °C and under anhydrous conditions, to a solution of cap-
rolactam (6.85 g, 31.6 mmol) and Et3N (5.3 mL, 38 mmol) in CCl4
(30 mL). The reaction mixture was stirred at ambient temperature
for 3 h, and then filtered to remove the precipitate. The precipitate
was washed with CCl4 (2 ꢁ 10 mL). The combined filtrate and wash-
ings were washed with water. The organic phase was dried over
anhydrous Na2SO4, and concentrated under reduced pressure. The
crude residue was purified by column chromatography on silica
gel (eluent: hexane/EtOAc, 15:1) to give N-(p-methylphenylthio)-
CDCl3): d 8.11 (d, 2H, J = 8.0 Hz), 8.02–8.00 (m, 2H, ArH), 7.63–
7.14 (m, 29H, ArH), 6.24 (t, 1H, J = 9.5 Hz), 5.26 (dd, 1H, J = 11.0,
3.5 Hz), 5.20 (d, 1H, J = 3.5 Hz), 5.17 (d, 1H, J = 3.5 Hz), 4.86–4.83
(m, 2H), 4.70–4.64 (m, 3H), 4.47 (d, 1H, J = 11.0 Hz), 4.38–4.27
(m, 4H), 4.21 (d, 1H, J = 12.0 Hz), 4.10 (d, 1H, J = 12.0 Hz), 4.05 (t,
1H, J = 6.8 Hz), 3.96–3.93 (m, 2H), 3.86 (dd, 1H, J = 10.0, 4.0 Hz),
3.49–3.47 (m, 1H), 3.46 (s, 3H), 3.41 (dd, 1H, J = 9.0, 6.0 Hz). The
spectral data were consistent with those in the literature.14
4.5. Methyl (2,3-di-O-benzyl-4,6-O-benzylidene-a-D-galacto-
pyranosyl)-(1?4)-2,3,6-tri-O-benzoyl- -glucopyranoside (16)
a-D
e
-caprolactam as white solid (6.56 g, 88%). Crystallization from hex-
ane–EtOAc afforded white needle shaped crystal; mp 70–72 °C; 1H
NMR (400 MHz, CDCl3): d 7.28–7.26 (m, 2H, ArH), 7.13–7.11 (m,
2H, ArH), 3.86–3.83 (m, 2H), 2.70–2.67 (m, 2H), 2.31 (s, 3H), 1.72–
1.65 (m, 6H); 13C NMR (100 MHz, CDCl3): d 178.1 (C@O), 137.9,
134.4, 130.0, 128.4, 58.3, 37.3, 29.8, 29.2, 23.5, 21.3; HRMS (ESI-
TOF) calcd for C13H17NOSNa [M+Na]+ 258.0929, found 258.0926.
A mixture of 1522a,30 (60.2 mg, 0.1087 mmol), 7 (50.0 mg,
0.0988 mmol), N-(p-methylphenylthio)- -caprolactam (28.2 mg,
0.1195 mmol) and flame activated 4 Å MS was stirred in dry CH2Cl2
e
(2 mL) for 30 min at ambient temperature. The reaction mixture
was then cooled to ꢀ5 °C. After stirring for 5 min, TMSOTf (24
lL,
0.1326 mmol) was added via a micro-syringe. The reaction mixture
was further stirred for 30 min at ꢀ5 °C and then warmed gradually
to ambient temperature. The reaction was then quenched with
4.3. Methyl (2,3,4-tri-O-benzyl-
a-L-fucopyranosyl)-(1?4)-2,3,6-
tri-O-benzoyl-1-thio- -glucopyranoside (8)
a
-
D
Et3N (220 lL), filtered off through a pad of Celite, and concen-
trated. The crude mixture was directly purified by silica gel flash
column chromatography (hexane/EtOAc, 4:1) to afford 1614
(82.5 mg, 89%) as a white foam. Rf 0.22 (20% EtOAc in hexane).
A mixture of 228 (46.9 mg, 0.0869 mmol), 729 (40.0 mg, 0.0791
mmol), N-(p-methylphenylthio)- -caprolactam (22.0 mg, 0.0932
mmol), and flame activated 4 Å MS were stirred in dry CH2Cl2
e
½
a 2D6 +117.4 (c 1.07, CHCl3); 1H NMR (500 MHz, CDCl3): d 8.13–
ꢂ
(3 mL) for 30 min at ambient temperature. The reaction mixture
8.11 (m, 2H, ArH), 8.02–7.99 (m, 4H, ArH), 7.63–7.14 (m, 24H,
ArH), 6.24 (t, 1H, J = 10.0 Hz), 5.40 (s, 1H, PhCH), 5.32 (d, 1H,
J = 3.5 Hz), 5.23 (dd, 1H, J = 10.0, 3.5 Hz), 5.18 (d, 1H, J = 3.5 Hz),
4.84 (dd, 1H, J = 12.0, 3.5 Hz), 4.67 (d, 1H, J = 12.0 Hz, PhCHaHb),
4.63 (d, 1H, J = 12.0 Hz, PhCHaHb), 4.51 (dd, 1H, J = 12.0, 4.0 Hz),
4.36–4.32 (m, 2H), 4.26 (m, 1H), 4.21–4.17 (m, 2H), 4.00–3.91
(m, 3H), 3.82 (dd, 1H, J = 12.5, 1.5 Hz), 3.67 (s, 1H), 3.44 (s, 3H).
The spectral data were consistent with those in the literature.14
was then cooled to ꢀ45 °C. After stirring for 5 min, TMSOTf (19
lL,
0.105 mmol) was added to the reaction mixture via a micro-syringe.
The reaction was further stirred for 10 min and then warmed grad-
ually to ambient temperature over 30 min. The reaction was
quenched with Et3N (150 lL), filtered off through a pad of Celite,
and concentrated. The crude residue was directly purified by silica
gel flash column chromatography (hexane/EtOAc, 6:1) to afford 8
(67.2 mg, 92%) as a white foam. Rf 0.24 (25% EtOAc in hexane);
½
a 2D6
ꢂ
+46.2 (c 1.06, CHCl3); 1H NMR (600 MHz, CDCl3): d 8.12–8.11
4.6. Methyl (4-O-acetyl-2,3-di-O-benzyl-6-O-tert-butyldi-
(m, 2H, ArH), 7.96–7.93 (m, 4H, ArH), 7.62 (m, 1H, ArH), 7.52–7.22
(m, 23H, ArH), 6.02 (t, 1H, J = 9.6 Hz), 5.14–5.12 (m, 2H, H-1), 4.96
(dd, 1H, J = 12.0, 1.8 Hz), 4.93 (d, 1H, J = 3.0 Hz, H-10), 4.89–4.82
(m, 3H), 4.79–4.76 (m, 2H), 4.73 (d, 1H, J = 12.0 Hz), 4.54 (d, 1H,
J = 12.0 Hz), 4.20 (dd, 1H, J = 9.6, 2.4 Hz), 4.05 (t, 1H, J = 9.6 Hz),
4.01 (dd, 1H, J = 10.8, 3.6 Hz), 3.97 (dd, 1H, J = 10.2, 2.4 Hz), 3.83
(q, 1H, J = 6.6 Hz, H-5), 3.54 (br s, 1H), 3.42 (s, 3H), 0.67 (d, 1H,
J = 6.0 Hz); 13C NMR (150 MHz, CDCl3): d 166.1 (C@O), 166.0
(C@O), 165.9 (C@O), 138.6, 138.4, 138.0, 133.2, 133.1, 132.9,
130.0, 129.8, 129.73, 129.68, 129.66, 129.0, 128.42, 128.41,
128.35, 128.31, 128.27, 128.2, 128.1, 127.7, 127.5, 127.44, 127.36,
100.6 (C-10), 96.6 (C-1), 79.3, 77.6, 76.7, 75.6, 74.8, 74.3, 72.6, 72.4,
71.7, 69.0, 67.6, 63.0, 55.3, 16.0; HRMS (ESI-TOF) calcd for
phenylsilyl-a-D-galactopyranosyl)-(1?4)-2,3,6-tri-O-benzoyl-a-
D-glucopyranoside (18)
A
mixture of 17 (48.6 mg, 0.0651 mmol),
7
(30.0 mg,
0.0593 mmol), N-(p-methylphenylthio)- -caprolactam (17.0 mg,
e
0.072 mmol), and flame activated 4 Å MS was stirred in dry CH2Cl2
(3 mL) for 30 min at ambient temperature. The reaction mixture
was then cooled to ꢀ45 °C, stirred for 5 min followed by addition
of TMSOTf (14 lL, 0.0774 mmol). The reaction mixture was
warmed gradually to ꢀ10 °C over 30 min. The reaction was then
quenched with Et3N (130 L), filtered off through a pad of Celite,
l
and concentrated. The crude residue was directly purified by silica
gel flash column chromatography (hexane/EtOAc,) to afford 18
(60.9 mg, 91%) as a white foam. Rf 0.32 (20% EtOAc in hexane).
C
55H54O13Na [M+Na]+ 945.3462, found 945.3455.
½
a 2D6 +77.7 (c 1.0 , CHCl3); 1H NMR (500 MHz, CDCl3): d 8.04–7.97
ꢂ
4.4. Methyl (2,3,4,6-tetra-O-benzyl-
a-D
-galactopyranosyl)-
(m, 6H, ArH), 7.65–7.10 (m, 29H, ArH), 6.15 (m, 1H), 5.65 (d, 1H,
J = 2.0 Hz), 5.24 (dd, 1H, J = 10.5, 3.5 Hz, H-1), 5.15 (d, 1H,
J = 3.5 Hz), 4.98 (d, 1H, J = 3.5 Hz, H-10), 4.79 (d, 1H, J = 12.0 Hz),
4.71 (d, 1H, J = 10.5 Hz), 4.57 (dd, 1H, J = 12.0, 2.5 Hz), 4.37 (d,
1H, J = 10.5 Hz), 4.25–4.20 (m, 2H), 4.16–4.13 (m, 2H), 3.96–3.93
(m, 2H), 3.67 (dd, 1H, J = 10.0, 6.5 Hz), 3.57 (dd, 1H, J = 10.0,
7.0 Hz), 3.51 (dd, 1H, J = 10.0, 3.5 Hz), 3.46 (s, 3H, OCH3), 1.88 (s,
3H, COCH3), 1.07 (s, 9H); 13C NMR (125 MHz, CDCl3): d 169.9
(C@O), 166.2 (C@O), 166.0 (C@O), 165.8 (C@O), 138.6, 138.4,
135.8, 135.7, 133.4, 133.3, 133.2, 133.1, 132.9, 130.3, 130.1,
(1?4)-2,3,6-tri-O-benzoyl- -glucopyranoside (14)
a-D
A
mixture of 1322a (56.2 mg, 0.087 mmol),
0.0791 mmol), N-(p-methylphenylthio)- -caprolactam (22.6 mg,
7 (40.0 mg,
e
0.0958 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to ꢀ45 °C. After stirring for 5 min,
TMSOTf (19 lL, 0.105 mmol) was added to reaction mixture via a
micro-syringe. The reaction was further stirred for 10 min and then

S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
45
130.07, 129.92, 129.87, 129.8, 129.3, 128.6, 128.51, 128.41, 128.32,
4.9. Methyl (2,3,4,6-tetra-O-benzoyl-b-
D-galactopyranosyl)-
128.29, 128.25, 127.94, 127.88, 127.6, 127.5, 99.9 (C-10), 96.9 (C-1),
76.6, 74.7, 73.1, 72.5, 72.2, 71.7, 70.8, 69.2, 67.9, 63.5, 62.1, 55.6,
26.9, 20.9, 19.2. HRMS (ESI-TOF) calcd for C66H68O15SiNa [M+Na]+
1151.4225, found 1151.4214.
(1?6)-2,3,4-tri-O-benzoyl-
a-D
glucopyranoside (26)6
A solution of 2521,22a (53.7 mg, 0.0763 mmol), 23 (35.1 mg,
0.0694 mmol), N-(p-methylphenylthio)- -caprolactam (19.8 mg,
e
0.0839 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to ꢀ45 °C, stirred for 5 min followed by
4.7. Methyl (2-O-acetyl-3,4,6-tri-O-benzyl-
a-D-mannopyra-
nosyl)-(1?4)-3,4,6-tri-O-benzyl- -mannopyranoside (21)
a
-D
the addition of TMSOTf (17 lL, 0.0939 mmol). The reaction mixture
A mixture of 1931 (49.0 mg, 0.0839 mmol), 2032 (35.5 mg,
0.0765 mmol), N-(p-methylphenylthio)- -caprolactam (22.0 mg,
was warmed gradually to ambient temperature over 30 min. The
e
reaction was then quenched with Et3N (160 L), filtered off
l
0.0932 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to ꢀ45 °C. After stirring for 5 min,
through a pad of Celite, and concentrated. The crude residue was
directly purified by silica gel flash column chromatography (hex-
ane/EtOAc, 6:1) to afford 266 (71.8 mg, 95%) as a white foam. Rf
TMSOTf (18
lL, 0.0995 mmol) was injected into the reaction mix-
0.22 (20% EtOAc in hexane); ½a D24
ꢂ
+77.2 (c 1.1, CHCl3); Lit.6
½ ꢂ
a 2D0
ture via a micro-syringe. The reaction mixture was warmed grad-
ually to ambient temperature over 30 min. The reaction was then
quenched with Et3N (170 lL), filtered off through a pad of Celite,
+78.1 (c 1.0, CDCl3); 1H NMR (500 MHz, CDCl3): d 8.03–8.01 (m,
2H, ArH), 7.97–7.95 (m, 4H, ArH), 7.90–7.84 (m, 4H, ArH), 7.76–
7.73 (m, 4H, ArH), 7.57–7.17 (m, 21H, ArH), 6.04 (t, 1H,
J = 10.0 Hz), 5.95 (d, 1H, J = 3.0 Hz), 5.80 (dd, 1H, J = 10.0, 8.0 Hz),
5.60 (dd, 1H, J = 10.0, 3.0 Hz), 5.29 (t, 1H, J = 10.0 Hz), 5.02 (dd,
1H, J = 10.0, 3.5 Hz), 4.91 (d, 1H, J = 7.5 Hz), 4.87 (d, 1H,
J = 3.5 Hz), 4.56 (m, 1H), 4.36 (dd, 1H, J = 11.0, 7.0 Hz), 4.28 (t,
1H, J = 7.0 Hz), 4.21 (t, 1H, J = 9.0, 8.5 Hz), 4.13 (d, 1H,
J = 11.0 Hz), 3.76 (dd, 1H, J = 11.0, 7.5 Hz), 3.06 (s, 3H, OCH3). The
spectral data were consistent with those in the literature.6,21
and concentrated. The crude residue was directly purified by sil-
ica gel flash column chromatography (hexane/EtOAc, 4:1) to af-
ford 21 (68.2 mg, 95%) as a white foam. Rf 0.28 (25% EtOAc in
hexane). ½a 2D6
ꢂ
+28.2 (c 1.0, CHCl3); 1H NMR (600 MHz, CDCl3): d
7.34–7.13 (m, 30H, ArH), 5.47 (br s, 1H), 5.42 (br s, 1H, H-10),
4.80 (d, 1H, J = 10.8 Hz), 4.76 (s, 1H, H-1), 4.67 (d, 1H,
J = 10.8 Hz), 4.65–4.60 (m, 4H), 4.58–4.53 (m, 3H), 4.43 (br s,
1H), 4.41 (br s, 1H), 4.35 (d, 1H, J = 12.0 Hz), 4.16 (t, 1H,
J = 9.0 Hz), 3.85–3.84 (m, 3H), 3.77–3.70 (m, 5H), 3.63 (dd, 1H,
J = 10.8, 3.0 Hz), 3.43 (d, 1H, J = 10.8 Hz), 3.35 (s, 3H, OCH3), 2.01
(s, 3H, COCH3); 13C NMR (150 MHz, CDCl3): d 169.9 (C@O),
138.51, 138.48, 138.3, 138.2, 138.1, 137.9, 128.29, 128.27, 128.2,
128.0, 127.9, 127.82, 127.76, 127.61, 127.57, 127.52, 127.45,
127.4, 127.3, 99.4 (C-1), 98.7 (C-10), 80.1, 78.4, 75.0, 74.0, 73.9,
73.4, 73.2, 72.5, 72.3, 71.7, 71.4, 71.1, 69.9, 68.6, 68.5, 54.9,
21.0; HRMS (ESI-TOF) calcd for C57H62O12Na [M+Na]+ 961.4139,
found 961.4131.
4.10. Methyl (2,3,4,6-tetra-O-benzoyl-b-D-galactopyranosyl)-
(1?4)-2,3,6-tri-O-benzyl- mannopyranoside (27)
a
-D
A
solution of 25 (54.4 mg, 0.0773 mmol), 20 (32.6 mg,
0.0703 mmol), N-(p-methylphenylthio)- -caprolactam (20.0 mg,
e
0.0847 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (2 mL) for 0.5 h at ambient temperature. The reaction mix-
ture was then cooled to ꢀ45 °C. After stirring for 5 min, TMSOTf
(17 lL, 0.0939 mmol) was injected into the reaction mixture via
a micro-syringe. The reaction mixture was then warmed gradually
4.8. Methyl (2-O-acetyl-3-O-benzyl-4,6-O-benzylidene-b-
D-glu-
to ambient temperature. The reaction was then quenched with
copyranosyl)-(1?6)-2,3,4-tri-O-benzoyl- -glucopyranoside (24)
a
-
D
Et3N (160 lL), filtered off through a pad of Celite, and concen-
trated. The crude residue was directly purified by silica gel flash
column chromatography (hexane/EtOAc, 4:1) to afford 27
(68.3 mg, 93%) as a white foam. Rf 0.21 (25% EtOAc in hexane).
A mixture of 2233 (40.0 mg, 0.0901 mmol), 2334 (41.4 mg,
0.0818 mmol), N-(p-methylphenylthio)- -caprolactam (23.4 mg,
0.0992 mmol), and flame activated 4 Å MS were stirred in dry
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to 0 °C. After stirring for 5 min, TMSOTf
e
½
a 2D6 +59.5 (c 1.06, CHCl3); 1H NMR (600 MHz, CDCl3): d 7.97 (d,
ꢂ
2H, J = 7.2 Hz, ArH), 7.94 (d, 2H, J = 7.8 Hz, ArH), 7.89 (d, 2H,
J = 7.8 Hz, ArH), 7.76 (d, 2H, J = 7.2 Hz, ArH), 7.57–7.17 (m, 27H,
ArH), 5.87 (d, 1H, J = 3.6 Hz), 5.72 (dd, 1H, J = 10.2, 8.4 Hz), 5.40
(dd, 1H, J = 10.8, 3.6 Hz), 4.99 (d, 1H, J = 8.4 Hz, H-10), 4.92 (d, 1H,
J = 12.0 Hz), 4.73–4.67 (m, 3H, H-1), 4.61 (d, 1H, J = 12.0 Hz), 4.40
(apparent t, 1H, J = 6.0, 4.8 Hz), 4.37 (apparent t, 1H, J = 9.6,
9.0 Hz), 4.26 (dd, 1H, J = 12.0, 8.0 Hz), 3.94 (t, 1H, J = 6.6 Hz), 3.90
(dd, 1H, J = 3.0 Hz), 3.76 (t, 1H, J = 2.4 Hz), 3.64–3.60 (m, 2H),
3.39 (d, 1H, J = 9.6 Hz), 3.25 (s, 3H, OCH3); 13C NMR (150 MHz,
CDCl3): d 166.0 (C@O), 165.7 (C@O), 165.6 (C@O), 165.3 (C@O),
139.3, 138.6, 133.5, 133.4, 133.30, 133.26, 130.0, 129.9, 129.7,
129.4, 129.3, 129.0, 128.7, 128.57, 128.55, 128.4, 128.0, 127.9,
127.6, 127.4, 127.0, 101.2 (C-10), 99.5 (C-1), 78.5, 75.6, 73.5, 73.0,
72.7, 72.1, 71.2, 70.7, 68.8, 61.8, 54.9; HRMS (ESI-TOF) calcd for
(20
tion mixture was further stirred for 30 min at the same tempera-
ture, and then the reaction was quenched with Et3N (190 L),
lL, 0.1105 mmol) was injected via a micro-syringe. The reac-
l
filtered off through a pad of Celite, and concentrated. The crude
residue was directly purified by silica gel flash column chromatog-
raphy (hexane/EtOAc, 3:1) to afford 24 (64.1 mg, 88%) as a white
foam. Rf 0.30 (25% EtOAc in hexane); mp 185–186 °C; ½a D26
ꢂ
+29.6
(c 1.0, CHCl3); 1H NMR (300 MHz, CDCl3): d 7.99–7.94 (m, 4H,
ArH), 7.88–7.85 (m, 2H, ArH), 7.54–7.49 (m, 4H, ArH), 7.42–7.35
(m, 8H, ArH), 7.31–7.26 (m, 7H, ArH), 6.15 (t, 1H, J = 9.3 Hz), 5.55
(s, 1H, PhCH), 5.45 (t, 1H, J = 9.8 Hz), 5.27–5.23 (m, 1H), 5.23 (br
s, 1H, H-1), 5.08 (dt, 1H, J = 7.6, 2.4 Hz), 4.88 (d, 1H, J = 12.1 Hz),
4.69 (d, 1H, J = 12.1 Hz), 4.54 (d, 1H, J = 7.9 Hz, H-10), 4.31 (dd,
1H, J = 10.5, 4.9 Hz), 4.25 (m, 1H), 4.06 (dd, 1H, J = 10.8, 1.5 Hz),
3.77–3.71 (m, 3H), 3.68 (dd, 1H, J = 10.8, 6.7 Hz), 3.46 (s, 3H,
OCH3), 3.42 (m, 1H), 2.07 (s, 3H, COCH3); 13C NMR (75 MHz, CDCl3):
d 169.4 (C@O), 165.8 (C@O), 165.7 (C@O), 165.3 (C@O), 138.2,
137.1, 133.5, 133.3, 133.0, 129.9, 129.8, 129.6, 129.03, 128.99,
128.87, 128.43, 128.40, 128.3, 128.2, 127.8, 127.6, 126.0, 101.8
(C-10), 101.2, 96.7 (C-1), 81.4, 78.4, 74.1, 72.6, 72.0, 70.5, 69.4,
68.5, 68.3, 66.2, 55.4, 20.9; HRMS (ESI-TOF) calcd for C50H48O15Na
[M+Na]+ 911.2891, found 911.2889.
C
62H58O15Na [M+Na]+ 1065.3673, found 1065.3665.
4.11. Methyl (3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-b-
D-glu-
copyranosyl)-(1?6)-2,3,4-tri-O-benzoyl-a-D-glucopyranoside
(28)
A
solution of 1035 (46.6 mg, 0.0884 mmol), 23 (40.7 mg,
0.0804 mmol), N-(p-methylphenylthio)- -caprolactam (23.0 mg,
e
0.0975 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (2 mL) for 30 min at room temperature. The reaction mix-

46
S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
ture was then cooled to ꢀ45 °C. After stirring for 5 min, TMSOTf
(19 L, 0.105 mmol) was added via a micro-syringe. The reaction
mixture was warmed gradually to ambient temperature over
30 min. The reaction was then quenched with Et3N (180 L), fil-
tered off through a pad of Celite, and concentrated. The crude res-
idue was directly purified by silica gel flash column
chromatography (hexane/EtOAc, 11:9) to afford 2836 (70.7 mg,
2H), 4.58 (dd, 1H, J = 12.0, 5.0 Hz), 4.44 (d, 1H, J = 11.0 Hz), 4.31
(d, 1H, J = 12.0 Hz), 4.25 (d, 1H, J = 12.5 Hz), 4.24–4.16 (m, 2H),
4.01–3.94 (m, 3H), 3.90 (s, 1H), 3.86 (dd, 1H, J = 10.5, 2.5 Hz),
3.78 (dd, 1H, J = 10.0, 3.5 Hz), 3.45–3.37 (m, 2H), 2.26 (s, 3H). The
spectral data were consistent with those in the literature.14
l
l
4.14. Phenyl (2-O-acetyl-3,4,6-tri-O-benzyl-
a-D
-mannopyrano-
95%) as a white foam. Rf 0.20 (40% EtOAc in hexane). ½a D24
ꢂ
+45.3
syl)-(1?6)-2,3,4-tri-O-benzoyl-1-thio-a-D-mannopyranoside
(33)
(c 1.65, CHCl3); 1H NMR (500 MHz, CDCl3): d 7.92–7.85 (m, 4H,
ArH), 7.80–7.73 (m, 6H, ArH), 7.49–7.46 (m, 2H, ArH), 7.40–7.32
(m, 5H, ArH), 7.25–7.22 (m, 2H, ArH), 6.00 (t, 1H, J = 10.0 Hz),
5.81 (t, 1H, J = 10.0 Hz), 5.41 (d, 1H, J = 8.0 Hz), 5.26 (t, 1H,
J = 10.0 Hz), 5.15 (t, 1H, J = 9.5 Hz), 5.06 (dd, 1H, J = 10.0, 3.5 Hz),
4.72 (d, 1H, J = 3.5 Hz), 4.36 (t, 1H, J = 10.0, 9.0, Hz), 4.31 (dd, 1H,
J = 12.5, 4.5 Hz), 4.12–4.10 (m, 2H), 4.05 (d, 1H, J = 10.5 Hz), 3.87
(d, 1H, J = 7.5 Hz), 3.61 (dd, 1H, J = 10.0, 7.5 Hz), 3.08 (s, 3H,
OCH3), 2.05 (s, 3H, COCH3), 2.02 (s, 3H, COCH3), 1.86 (s, 3H, COCH3).
The spectral data were consistent with those in the literature.36
A solution of 19 (40.0 mg, 0.0685 mmol), 3238 (40.1 mg, 0.0685
mmol), N-(p-methylphenylthio)- -caprolactam (17.8 mg, 0.0754
e
mmol), and flame activated 4 Å MS were stirred in dry CH2Cl2
(3 mL) for 30 min at room temperature. The reaction mixture was
then cooled to ꢀ10 °C. After stirring for 5 min, TMSOTf (15
lL,
0.0829 mmol) was injected via a micro-syringe. The reaction mix-
ture was warmed gradually to ambient temperature over 1 h. The
reaction was then quenched with Et3N (130 lL), filtered off through
a pad of Celite, and concentrated. The crude residue was directly
purified by silica gel flash column chromatography (hexane/EtOAc,
3:1) to afford 33 (68.2 mg, 94%) as a white foam. Rf 0.25 (30% EtOAc
4.12. p-Methylphenyl (2,3,4-tri-O-benzyl-
a-L-fucopyranosyl)-
(1?4)-2,3,6-tri-O-benzoyl-1-thio-b- -glucopyranoside (30)
D
in hexane); ½a 2D6
ꢂ
+16.3 (c 1.34, CHCl3); 1H NMR (600 MHz, CDCl3): d
A
solution of
2
(40.7 mg, 0.0754 mmol), 2922a (45.0 mg,
0.0753 mmol), N-(p-methylphenylthio)- -caprolactam (19.6 mg,
8.07 (d, 2H, J = 7.2 Hz, ArH), 8.00 (d, 2H, J = 7.2 Hz, ArH), 7.85 (d, 2H,
J = 7.2 Hz, ArH), 7.57–7.41 (m, 9H, ArH), 7.35–7.22 (m, 19H, ArH),
7.16–7.13 (m, 3H, ArH), 5.99 (t, 1H, J = 10.2 Hz), 5.94 (m, 1H), 5.81
(dd, 1H, J = 9.6, 3.0 Hz), 5.73 (d, 1H, J = 1.2 Hz, H-1), 5.36 (dd, 1H,
J = 3.0, 1.8 Hz), 4.87 (d, 1H, J = 1.3 Hz, H-10), 4.84 (d, 1H,
J = 10.8 Hz), 4.81 (m, 1H), 4.58 (d, 1H, J = 12.0 Hz), 4.50 (d, 1H,
J = 10.8 Hz), 4.44 (d, 1H, J = 10.8 Hz), 4.36 (d, 1H, J = 12.0 Hz), 4.32
(d, 1H, J = 10.8 Hz), 4.00 (dd, 1H, J = 10.8, 5.4 Hz), 3.95 (dd, 1H,
J = 9.6, 3.6 Hz), 3.87 (t, 1H, J = 9.6 Hz), 3.75 (dd, 1H, J = 10.2,
3.0 Hz), 3.69 (m, 1H), 3.68 (m, 1H), 3.53 (d, 1H, J = 9.6 Hz), 2.10 (s,
3H, COCH3); 13C NMR (150 MHz, CDCl3): d 170.3 (C@O), 165.44
(C@O), 165.36 (C@O), 138.5, 138.0, 137.9, 133.6, 133.5, 133.25,
133.22, 132.1, 131.5, 129.92, 129.89, 129.8, 129.74, 129.71, 129.4,
129.3, 129.2, 128.9, 128.6, 128.54, 128.47, 128.4, 128.32, 128.27,
128.23, 128.18, 128.0, 127.90, 127.88, 127.7, 127.51, 127.50, 98.0
(C-10), 86.0 (C-1), 78.4, 75.1, 74.0, 73.2, 72.0, 71.8, 71.5, 70.48,
70.45, 68.46, 68.44, 67.3, 66.6, 21.0, HRMS (ESI-TOF) calcd for
e
0.0831 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to ꢀ45 °C. After stirring for 5 min,
TMSOTf (17 lL, 0.0939 mmol) was injected into the reaction mix-
ture via a micro-syringe. The reaction mixture was warmed gradu-
ally to ambient temperature over 30 min. The reaction was then
quenched with Et3N (160 lL), filtered off through a pad of Celite,
and concentrated. The crude residue was directly purified by silica
gel flash column chromatography (hexane/EtOAc, 5:1) to afford
3014,37 (68.7 mg, 90%) as a white foam. Rf 0.30 (25% EtOAc in hex-
ane). ½a 2D4
ꢂ
ꢀ8.2 (c 0.98, CHCl3); 1H NMR (500 MHz, CDCl3): d 8.08–
8.07 (m, 2H, ArH), 7.90–7.89 (m, 2H, ArH), 7.85–7.83 (m, 2H, ArH),
7.64 (m, 1H, ArH), 7.52–7.19 (m, 25H, ArH), 6.87–6.85 (m, 2H), 5.69
(apparent t, 1H, J = 9.5, 9.0 Hz), 5.24 (t, 1H, J = 9.5 Hz), 5.06 (dd, 1H,
J = 12.0, 1.5 Hz), 4.86–4.82 (m, 4H), 4.79 (d, 1H, J = 12.0 Hz), 4.73 (d,
1H, J = 12.0 Hz), 4.68 (d, 1H, J = 11.5 Hz), 4.64 (dd, 1H, J = 12.0,
4.5 Hz), 4.50 (d, 1H, J = 11.5 Hz), 3.97–3.93 (m, 2H), 3.91–3.87 (m,
2H), 3.71 (q, 1H, J = 6.0 Hz), 3.45 (br s, 1H), 2.23 (s, 3H), 0.60 (d,
3H, J = 6.0 Hz). The spectral data were consistent with those in
the literature.37
C
62H58O14SNa [M+Na]+ 1081.3445, found 1081.3441.
4.15. p-Methylphenyl (2,3-di-O-benzoyl-4,6-O-benzylidene-b-D-
galactopyranosyl)-(1?6)-2,3,4-tri-O-benzoyl-b-D-glucopyrano-
side (36)
4.13. p-Methylphenyl (2,3,4,6-tetra-O-benzyl-
a
-
D
-galactopyra-
A solution of 3439 (48.7 mg, 0.0837 mmol), 3534c (50.0 mg,
0.0836 mmol), N-(p-methylphenylthio)- caprolactam (21.7 mg,
0.0919 mmol) and flame activated 4 Å MS was stirred in dry CH2Cl2
(2 mL) for 30 min at ambient temperature. The reaction mixture
nosyl)-(1?4)-2,3,6-tri-O-benzoyl-1-thio-b-
D-glucopyranoside
e
(31)
A
solution of 13 (43.3 mg, 0.067 mmol), 29 (40.0 mg,
was then cooled to ꢀ5 °C. After stirring for 5 min, TMSOTf (18
lL,
0.0669 mmol), N-(p-methylphenylthio)-e-caprolactam (17.4 mg,
0.0995 mmol) was injected into the reaction mixture via a micro-
syringe. The reaction mixture was further stirred for 1 h at ꢀ5 °C
and then warmed gradually to ambient temperature. The reaction
0.0737 mmol), and flame activated 4 Å MS was stirred in dry
CH2Cl2 (3 mL) for 30 min at room temperature. The reaction mix-
ture was then cooled to ꢀ45 °C. After stirring for 5 min, TMSOTf
mixture was then quenched with Et3N (170 lL), filtered off
(15 lL, 0.0829 mmol) was injected via a micro-syringe. The reac-
through a pad of Celite, and concentrated. The crude mixture was
directly purified by silica gel flash column chromatography (hex-
ane/EtOAc, 2:1) to afford 3621 (76.8 mg, 87%) as a white foam. Rf
tion mixture was warmed gradually to room temperature over
30 min. The reaction was quenched with Et3N (140 L), filtered
off through a pad of Celite, and concentrated. The crude residue
was directly purified by silica gel flash column chromatography
(hexane/EtOAc, 5:1) to afford 3114 (69.8 mg, 93%) as a white foam.
l
0.28 (30% EtOAc in hexane); ½a D24
ꢂ
+51.2 (c 1.1, CHCl3); Lit.21
½ ꢂ
a 2D7
+50.0 (c 1.0, CDCl3); 1H NMR (500 MHz, CDCl3): d 7.93–7.90 (m,
2H, ArH), 7.87–7.84 (m, 4H, ArH), 7.78–7.60 (m, 2H, ArH), 7.66
(d, 2H, J = 8.0 Hz, ArH), 7.45–7.23 (m, 20H, ArH), 7.17–7.14 (m,
2H, ArH), 7.02 (d, 2H, J = 8.0 Hz, ArH), 5.80 (dd, 1H, J = 10.5,
8.0 Hz), 5.68 (t, 1H, J = 9.5 Hz), 5.45 (s, 1H, PhCH), 5.27–5.19 (m,
3H), 4.87 (d, 1H, J = 8.0 Hz), 4.72 (d, 1H, J = 10.0 Hz), 4.52 (d, 1H,
J = 3.5 Hz), 4.22 (d, 1H, J = 12.5 Hz), 4.03–3.92 (m, 3H), 3.86 (dd,
Rf 0.30 (25% EtOAc in hexane); ½a D26
ꢂ
+30.6 (c 1.02, CHCl3); 1H NMR
(500 MHz, CDCl3): d 8.06–8.04 (m, 2H, ArH), 7.97–7.92 (m, 4H,
ArH), 7.64 (t, 1H, J = 7.5 Hz, ArH), 7.53–7.07 (m, 30H, ArH), 6.90
(d, 2H, J = 8.0 Hz, ArH), 5.86 (t, 1H, J = 9.0 Hz), 5.37 (t, 1H,
J = 10.0 Hz), 5.00 (d,1H, J = 3.5 Hz), 4.96 (dd, 1H, J = 12.0, 2.0 Hz),
4.89 (d, 1H, J = 9.5 Hz), 4.79 (d, 1H, J = 11.0 Hz), 4.64–4.61 (m,

S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
47
1H, J = 11.5, 7.5 Hz), 3.56 (s, 1H), 2.22 (s, 3H). The spectral data
CH2Cl2 (3 mL) for 30 min at ambient temperature. The reaction
mixture was then cooled to 0 °C. After stirring for 5 min, TMSOTf
were consistent with those in the literature.21
(36 lL, 0.1989 mmol) was injected into the reaction mixture via
a micro-syringe. The reaction mixture was further stirred for
30 min and then warmed gradually to ambient temperature.
4.16. Glycosylation method for 39 and 40
The reaction was then quenched with Et3N (400 lL), filtered
A mixture of 3740 (0.0825 mmol), 3841 (0.075 mmol), N-(p-
methylphenylthio)-e-caprolactam (0.091 mmol), and flame acti-
off through a pad of Celite, and concentrated. The crude residue
was directly purified by silica gel flash column chromatography
(hexane/EtOAc, 1:2) to afford 4216 (66.2 mg, 81%) as a white
vated 4 Å MS was stirred in dry solvent (3 mL) for 30 min at room
temperature. The reaction mixture was then cooled to ꢀ45 °C.
After stirring for 5 min, TMSOTf (0.10 mmol) was injected via a mi-
cro-syringe. The reaction mixture was warmed gradually to ambi-
ent temperature over 30 min. The reaction was then quenched
with Et3N, filtered off through a pad of Celite, and concentrated.
The crude residue was directly purified by silica gel flash column
chromatography (CH2Cl2/hexane, 3:2) to afford the title
compounds.
foam. Rf 0.31 (60% EtOAc in hexane). ½a D24
ꢂ
+24.6 (c 1.0, CHCl3);
Lit.16
½
a 2D0 +23.9 (c 0.8, CHCl3); 1H NMR (500 MHz, CDCl3): d
ꢂ
7.88–7.87 (m, 2H, ArH), 7.79–7.75 (m, 4H, ArH), 7.67–7.65 (m,
2H, ArH), 7.33–7.32 (m, 4H, ArH), 7.26–7.21 (m, 4H, ArH),
7.16–7.15 (m, 2H, ArH), 5.69 (dd, 1H, J = 10.5, 9.5 Hz), 5.52 (dd,
1H, J = 10.5, 9.5 Hz), 5.47 (d, 1H, J = 8.5 Hz), 5.12–5.05 (m, 3H),
4.90 and 4.82 (d, each 1H, J = 12.0 Hz, PhCH2), 4.53 and 4.41
(d, each 1H, J = 12.0 Hz, PhCH2), 4.34 (dd, 1H, J = 12.5, 5.0 Hz),
4.20–4.11 (m, 4H), 4.08 (dd, 1H, J = 12.5, 4.0 Hz), 3.84 (dd, 1H,
J = 12.5, 2.5 Hz), 3.76 (apparent t, 1H, J = 9.5, 8.5 Hz), 3.68–3.66
(m, 2H), 3.59–3.52 (m, 2H), 3.40 (apparent t, 1H, J = 10.0,
9.0 Hz), 3.19–3.17 (m, 2H), 3.06 (s, 3H, OCH3), 2.12 (s, 3H,
COCH3), 2.03 (s, 3H, COCH3), 1.99 (s, 3H, COCH3), 1.97 (s, 3H,
COCH3), 1.84 (s, 3H, COCH3), 1.80 (s, 3H, COCH3). The spectral
data were consistent with those in the literature.16
Procedure A: solvent: CH2Cl2.
Procedure B: solvent: Et2O–CH2Cl2 (3:1).
Procedure C: solvent: CH3CN–CH2Cl2 (3:1).
4.16.1. Methyl (2,3,4,6-tetra-O-benzyl-
(1?4)-2,3,6-tri-O-benzyl- -glucopyranoside (39) and Methyl
(2,3,4,6-tetra-O-benzyl-b- -glucopyranosyl)-(1?4)-2,3,6-tri-O-
benzyl-
-glucopyranoside (40)43
a-D-glucopyranosyl)-
a-D
D
a
-D
Reaction of 37 with 38 following the procedure A, afforded 39
and 40 in 45% and 42% yields, respectively. Following the proce-
dure B, the corresponding yields were 72% and 19%, whereas pro-
cedure C provided 39 and 40 in 21% and 68% yields.
4.18. Methyl (2,3,4,6-tetra-O-benzyl-
(1?4)-(2,3,6-tri-O-benzoyl-b- -glucopyranosyl)-(1?4)-2,3,6-
tri-O-benzyl- -glucopyranoside (43)
a-D-galactopyranosyl)-
D
a-D
Compound 39:42 syrupy oil; Rf 0.43 (80% CH2Cl2 in hexane);
A solution of 13 (54.0 mg, 0.0836 mmol), 29 (50.0 mg, 0.0836
mmol), N-(p-methylphenylthio)- -caprolactam (21.7 mg, 0.092
½
a 2D4
ꢂ
+46.2 (c 1.0, CHCl3); Lit.42a
½
a 2D0 +40 (c 1.1, CHCl3), Lit.19
[a]
D
ꢂ
e
+46 (c 0.6, CHCl3); 1H NMR (500 MHz, CDCl3): d 7.34–7.10 (m,
35H, ArH), 5.69 (d, 1H, J = 3.0 Hz), 5.03 (d, 1H, J = 11.5 Hz), 4.88
(d, 1H, J = 10.5 Hz), 4.80 (d, 1H, J = 11.0 Hz), 4.78 (d, 1H,
J = 10.0 Hz), 4.77 (d, 1H, J = 11.0 Hz), 4.70 (d, 1H, J = 12.0 Hz), 4.60
(d, 1H, J = 3.0 Hz), 4.58–4.55 (m, 3H), 4.51 (d, 1H, J = 12.0 Hz),
4.49 (s, 2H), 4.42 (d, 1H, J = 10.5 Hz), 4.28 (d, 1H, J = 12.0 Hz),
4.09 (t, 1H, J = 9.0 Hz), 4.04 (t, 1H, J = 9.0 Hz), 3.90 (t, 1H,
J = 9.5 Hz), 3.86–3.81 (m, 2H), 3.72 (d, 1H, J = 10.0 Hz), 3.66–3.62
(m, 2H), 3.59 (dd, 1H, J = 9.0, 3.5 Hz), 3.50 (d, 1H, J = 3.0 Hz), 3.48
(d, 1H, J = 3.0 Hz), 3.40 (br s, 1H), 3.38 (s, 3H, OCH3). The spectral
data were consistent with those in the literature.42a
mmol), and flame activated 4 Å MS was stirred in dry CH2Cl2
(2 mL) for 30 min at ambient temperature. The reaction mixture
was then cooled to ꢀ45 °C. After stirring for 5 min, TMSOTf
(18 lL, 0.0995 mmol) was injected via a micro-syringe and then
allowed to warm to ambient temperature. The formation of 31
was monitored by TLC (hexanes/EtOAc 3:1). After the starting
materials were consumed, 38 (35.2 mg, 0.0759 mmol) and N-(p-
methylphenylthio)-
added to the reaction mixture and stirred for 30 min. The solution
L, 0.105 mmol) was
e-caprolactam (22.0 mg, 0.0932 mmol) were
was cooled to ꢀ45 °C and then TMSOTf (19
l
injected into the reaction mixture, the mixture was stirred for
Compound 40.42 White solid; Rf 0.33 (80% CH2Cl2 in hexane); mp
5 min at ꢀ45 °C, and then for 2 h at ambient temperature. The
84–85 °C (hexanes), Lit.41a mp 88–89 °C, Lit.19 mp 79–81 °C (ether–
reaction was then quenched with Et3N (380 lL), filtered off
hexanes); ½a 2D4
ꢂ
+22.8 (c 1.15, CHCl3); Lit.42a
½
a 2D0
+20 (c 1.0, CHCl3),
ꢂ
through a pad of Celite, and concentrated. The crude mixture
was directly purified by silica gel flash column chromatography
(toluene/EtOAc, 10:1) to afford 43 (72.1 mg, 65%) as a colorless
Lit.19 +22 (c 0.4, CHCl3); 1H NMR (500 MHz, CDCl3): d 7.26–
[a]
D
7.18 (m, 35H, ArH), 5.09 (d, 1H, J = 11.5 Hz), 4.87 (d, 1H,
J = 11.0 Hz), 4.80 (d, 1H, J = 12.5 Hz), 4.80 (d, 1H, J = 11.5 Hz), 4.79
(s, 1H), 4.75 (d, 1H, J = 11.5 Hz), 4.75 (d, 1H, J = 9.5 Hz), 4.74 (d,
1H, J = 11.5 Hz), 4.60 (d, 1H, J = 12.5 Hz), 4.57 (d, 1H, J = 11.5 Hz),
4.57 (d, 1H, J = 4.0 Hz), 4.55 (d, 1H, J = 10.0 Hz), 4.44 (d, 1H,
J = 12.0 Hz), 4.39 (d, 1H, J = 12.0 Hz), 4.38 (d, 1H, J = 8.0 Hz), 4.38
(d, 1H, J = 12.5 Hz), 3.96 (t, 1H, J = 9.5 Hz), 3.84 (t, 1H, J = 9.5 Hz),
3.83 (dd, 1H, J = 10.5, 3.5 Hz), 3.71 (dd, 1H, J = 10.5, 1.5 Hz), 3.59
(t, 1H, J = 9.5 Hz), 3.54 (dd, 1H, J = 11.0, 5.0 Hz), 3.50–3.46 (m, 3H),
3.36 (m, 1H), 3.36 (s, 3H, OCH3), 3.29 (m, 1H). The spectral data were
consistent with those in the literature.42a
oil. Rf 0.56 (10% EtOAc in toluene); ½a D26
ꢂ
+32.5 (c 1.22, CHCl3);
1H NMR (300 MHz, CDCl3): d 8.02 (d, 2H, J = 7.6 Hz, ArH), 7.95
(d, 2H, J = 7.5 Hz, ArH), 7.87 (d, 2H, J = 7.2 Hz, ArH), 7.45–7.08
(m, 44H, ArH), 5.67 (t, 1H, J = 9.3 Hz), 5.43 (dd, 1H, J = 8.1,
1.8 Hz), 5.10 (d, 1H, J = 11.4 Hz), 4.94 (d, 1H, J = 3.6 Hz, H-1),
4.81–4.75 (m, 3H, H-10), 4.71–4.65 (m, 5H), 4.55–4.52 (m, 2H,
H-100), 4.46–4.42 (m, 2H), 4.37 (br s, 1H), 4.33 (br s, 1H), 4.28–
4.16 (m, 3H), 3.97–3.86 (m, 6H), 3.76 (dd, 1H, J = 9.9, 2.4 Hz),
3.66 (dd, 1H, J = 9.6, 1.5 Hz), 3.56 (br s, 1H), 3.51 (br s, 1H),
3.48–3.36 (m, 4H), 3.26 (s, 3H, OCH3); 13C NMR (75 MHz, CDCl3):
d 165.8 (C@O), 165.5 (C@O), 165.1 (C@O), 139.3, 138.8, 138.5,
138.4, 138.1, 137.8, 133.2, 132.9, 130.0, 129.79, 129.75, 129.3,
128.8, 128.4, 128.3, 128.19, 128.13, 128.11, 128.08, 127.95,
127.92, 127.85, 127.7, 127.6, 127.52, 127.48, 127.43, 127.37,
127.3, 127.0, 100.3 (C-10), 99.6 (C-1), 98.1 (C-100), 80.6, 78.8,
78.6, 77.5, 75.5, 75.3, 75.2, 75.0, 74.8, 74.7, 73.6, 73.5, 73.4,
73.3, 73.1, 72.9, 62.7, 63.6, 55.3. HRMS (ESI-TOF) calcd for
4.17. Methyl (3,4,6-tri-O-acetyl-2-deoxy-2-phathalimido-b-
D-
glucopyranosyl)-(1?4)-(3,4,6-tri-O-acetyl-2-deoxy-2-
phathalimido-b-D-glucopyranosyl)-(1?6)-2,3-di-O-benzyl-a-D-
glucopyranoside (42)
A
solution of 10 (85.9 mg, 0.163 mmol), 4143 (25.4 mg,
0.0679 mmol), N-(p-methylphenylthio)- -caprolactam (42.4 mg,
0.1797 mmol), and flame activated 4 Å MS were stirred in dry
e
C
89H88O19Na [M+Na]+ 1483.5818, found 1483.5812.

48
S. K. Maity et al. / Carbohydrate Research 354 (2012) 40–48
23. (a) Ghosh, R.; De, D.; Shown, B.; Maiti, S. B. Carbohydr. Res. 1999, 321, 1–3; (b)
Acknowledgments
Ghosh, R.; Chakraborty, A.; Maiti, D. K. Synth. Commun. 2003, 33, 1623–1632;
(c) Ghosh, R.; Chakraborty, A.; Maiti, S. Arkivoc 2004, xiv, 1–9; (d) Ghosh, R.;
Chakraborty, A.; Maiti, D. K.; Puranik, V. G. Tetrahedron Lett. 2005, 46, 8047–
8050; (e) Ghosh, R.; Chakraborty, A.; Maiti, D. K.; Puranik, V. G. Org. Lett. 2006,
8, 1061–1064; (f) Das Sarma, M.; Ghosh, R.; Patra, A.; Chowdhury, R.;
Chaudhuri, K.; Hazra, B. Org. Biomol. Chem. 2007, 5, 3115–3125; (g) Roy, S.;
Chakraborty, A.; Ghosh, R. Carbohydr. Res. 2008, 343, 2523–2529; (h) Roy, S.;
Chakraborty, A.; Chattopadhaya, S.; Bhattacharya, A.; Mukherjee, A. K.; Ghosh,
R. Tetrahedron 2010, 66, 8512–8521; (i) Basu, N.; Maity, S. K.; Singha, S.; Ghosh,
R. Carbohydr. Res. 2011, 346, 534–539.
Financial support from the CSIR, New Delhi, India (Scheme No.
01/2382/10/EMR-II) to R.G. and from the CAS-UGC and the FIST-
DST, India to the Department of Chemistry, Jadavpur University
are acknowledged. N.B. is grateful to the CSIR for providing a fel-
lowship (SRF).
24. (a) Maity, S. K.; Maiti, S.; Patra, A.; Ghosh, R. Tetrahedron Lett. 2008, 49, 5847–
5849; (b) Maity, S. K.; Patra, A.; Ghosh, R. Tetrahedron 2010, 66, 2809–2814.
25. Yamago, S.; Yamada, T.; Maruyama, T.; Yoshida, J. I. Angew. Chem., Int. Ed. 2004,
43, 2145–2148.
Supplementary data
Supplementary data (preparation of compound 17; copies of
spectra (1H, 13C NMR) of compounds 1 and 17; copies of spectra
(1H NMR) of compounds 12, 39 and 40; copies of 1H-, 13C- and
2D-NMR spectra of compounds 8, 18, 21, 24, 27, 33 and 43) asso-
ciated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.carres.2012.03.024.
26. Compound 12: 1H NMR (500 MHz, CDCl3): d 7.84–7.83 (m, 4H, ArH), 7.74–7.72
(m, 4H, ArH), 7.38–7.14 (m, 10H, ArH), 5.73–5.67 (m, 2H), 5.59 (d, 1H,
J = 11.0 Hz), 5.45 (d, 1H, J = 8.5 Hz), 5.10 (t, 1H, J = 9.5 Hz), 4.50 (d, 1H,
J = 11.5 Hz), 4.44 (d, 1H, J = 12.0 Hz), 4.36 (dd, 1H, J = 12.5, 4.0 Hz), 4.25–4.18
(m, 2H), 4.12 (t, 1H, J = 9.5 Hz), 3.94 (dd, 1H, J = 11.5, 1.0 Hz), 3.60–3.54 (m, 3H),
3.47 (dd, 1H, J = 11.0, 3.0 Hz), 2.03 (s, 3H, COCH3), 1.99 (s, 3H, COCH3), 1.89 (s,
3H, COCH3), 1.82 (s, 3H, COCH3).
27. (a) Lemieux, R. U. Pure Appl. Chem. 1971, 25, 527–548; (b) Lönn, H. J. Carbohydr.
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