A stereoselective ring-closing glycosylation via nonglycosylating pathway

Article abstract of DOI:10.1021/jo5006763

Two glycosyl partners were first coupled with as ester linkage, which upon reductive acetylation produced an α-acetoxy ether group. The subsequent activation with TfOH triggered the ring-closing process and provided the corresponding glycosidic bond in high β-selectivity without relying on neighboring group participation.

Full text of DOI:10.1021/jo5006763

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Note
A Stereoselective Ring-closing Glycosylation via Non-glycosylating Pathway
Han Liu, and Xuechen Li
J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/jo5006763 • Publication Date (Web): 30 May 2014
Downloaded from http://pubs.acs.org on June 2, 2014
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A Stereoselective Ringꢀclosing Glycosylation via
Nonꢀglycosylating Pathway
Han Liua and Xuechen Lia,b*
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a) Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong,
P. R. China. b) State Key Laboratory of Synthetic Chemistry, University of Hong Kong,
Hong Kong. Fax: 852 2857 1586; Tel: 852 2219 4992; Eꢀmail: xuechenl@hku.hk.
Abstract
Two glycosyl partners were first coupled with as ester linkage, which, upon reductive
acetylation, produced an αꢀacetoxy ether group. The subsequent activation with TfOH
triggered the ringꢀclosing process and provided the corresponding glycosidic bond in
high βꢀselectivity without relying on neighbouring group participation.
The past century has witnessed a great advance in chemical glycosylations, which have
enabled the construction of complex oligosaccharides for biological and therapeutic
applications.1 Building on the first conceptual glycosylation by Koenigs and Knorr more
than one hundred years ago,2 a plethora of modern methods have been developed.3
Although these achievements have allowed carbohydrates with complex structures to be
synthesized, if given enough time and resources, the development of new glycosylation
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methodologies leading to stereoselective construction of glycosidic linkages is still
important in preparative carbohydrate chemistry.
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Scheme 1. General glycosylation methods and our proposed ringꢀclosing glycosylation.
The typical glycosylation methods involve a glycosyl donor (i.e., a sugar with a latent
leaving group at the anomeric carbon) as an electrophile and an acceptor (e.g., a hydroxyl
group from a partially protected sugar) as the nucleophilic counterpart (Scheme 1). Upon
activation with a suitable promoter (e.g., Lewis acids), the anomeric latent leaving group
undergoes anomeric substitution by the nucleophilic glycosyl acceptor to form a
glycosidic linkage. Over the past decades, many latent leaving groups and the
corresponding activators have been developed to serve as the glycosyl donor, including
thioether,4 sulfoxide,5 halides,6 trichloroacetoimidate,7 Nꢀphenyl trifluoroacetoimidate,8
phosphate,9 phosphite,10 oꢀcarboxyl benzoate,11 oꢀalkynyl benzoate,12 terminal alkenyl
ether,13 lactol,14 glycal,15 pyranones,16 etc. Upon the glycosyl donor activation, the
oxocarbenium cation is often considered to be the critical intermediate, which can be
stabilized by the C2ꢀO participating group (e.g., acyl groups) to produce 1,2ꢀtrans
glycosidic linkage.17 Without the C2ꢀO participating group, the outcome of the resultant
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stereoselectivity is often complicated. Generally, although the kinetic anomeric effect
will favor the formation of αꢀglycosides, the mixture of both αꢀ and βꢀglycosides are
often obtained, whose distribution is subjected to various effects from solvent,
temperature, additives, glycosyl donor/promoter combination and the substrate
structure.18 New conceptual methods have emerged to control the anomeric
stereoselectivity. Of particular significance, these methods include intramolecular
aglycon delivery (IAD),19 conformationally locked glycosyl donors,20 and auxiliaryꢀbased
glycosylation.21
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In contrast to the traditional paradigm of chemical glycosylations, we reported herein a
ringꢀclosing glycosylation strategy, which resulted in high stereoselectivity without the
aid of a C2ꢀO participating group. As shown in Scheme 1, we conceived of the idea that
if two glycosyl partners were first coupled with an ester bond, which, upon reduction and
acetylation, would produce an αꢀacetoxy ether group, the subsequent activation with
Lewis acids or Brønsted acids would trigger a ringꢀclosing reaction to generate the
corresponding glycosidic bond. To the best of our knowledge, a disaccharide synthesis
via intramolecular cyclization from linear precursor is quite rare,22,23 and the ringꢀclosing
glycosylation via an αꢀacetoxy ether has not been reported previously.
Our initial studies started with a model system, as illustrated in Scheme 2. The
benzylated glucose 1 was readily converted into the corresponding acid via the activated
amide 2.24 Esterification with 1.0 equiv. of cyclohexanol was performed under
DCC/DMAP condition to give ester 3a in 82% yield. No epimerization was observed at
C2ꢀposition during the coupling reaction when 0.5 equiv. DMAP was used. The desired
αꢀacetoxy ether 4a was successfully obtained via Rychnovsky's reductive acetylation
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reaction25 in 91% yield as an inseparable mixture of diastereomers. A more advanced
model 4b containing a twoꢀsugar skeleton was obtained in a similar way. It is noted that
the compounds 4a/b were quite stable for long time storage.
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OBn
OBn
OTES
OBn
O
Ref. 24
a, b
OTES
CON(Boc)Bn
BnO
BnO
BnO
BnO
BnO
BnO
BnO
O
R
OH
BnO
BnO
O
1
2a
3a 82%
3b 75%
OBn
OH
OBn
OTES
OBn
O
c
d
e
BnO
BnO
BnO
BnO
BnO
BnO
O
O
R
R
Rychnovsky's
Reductive Acetylation
R
O
BnO
BnO
BnO
OAc
OAc
5a
4a 91%
4b 91%
6a
O
BnO
BnO
R =
BnO
3b/4b
OMe
3a/4a/5a/6a
(a) 10 eq. LiOH, 20 eq. H2O2, THF/H2O 4/1, 16 h; (b) 1 eq. ROH, 2 eq. DCC, 0.5 eq. DMAP, CH2Cl2, 4 h; (c)
(i) 2 eq. DIBAL-H, CH2Cl2, -78 οC, 40 min; (ii) 3 eq. pyridine, 2 eq. DMAP, 6 eq. Ac2O, -78 οC, 10 h, then 0
οC, 30 min. For details, see supporting information.
Scheme 2. Synthesis of model substrates and attempt of ringꢀclosing glycosylation.
With the model substrates in hand, we set out to screen conditions for the cyclization.
In our first attempt, the TES (triethylsilyl) group of 4a was removed by TBAF, and the
o
crude intermediate 5a was treated with 1.0 equiv. of nBu2BOTf in DCM at ꢀ40 C. The
cyclized product was formed in 58% yield as 1:1 mixture of anomers. The selection of
the TES group was quite critical, while the more stable TBDMS (tertꢀbutyldimethylsilyl)
group could not be easily removed under the same condition. Considering the significant
decomposition during the desilylation step, we turned to explore a oneꢀpot reaction,
hoping for a more straightforward and efficient process. In an encouraging precedent,
Mukaiyama and Kobayashi have reported that silylated alcohols could directly participate
in the glycosylation with a glycosyl acetate donor.26
Table 1. Optimization of the reaction conditions of intramolecular glycosylation.
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OBn
OTES
OBn
Conditions
O
BnO
BnO
BnO
BnO
O
R
R
O
BnO
BnO
OAc
3a, b
4a, b
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Entry
R
Activator
Eq. Solvent
Temp.
Yield%a
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(oC)
(α/β)b
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4a
4a
4a
4a
4a
Cu(OTf)2
Zn(OTf)2
TMSOTf
TBSOTf
BF3OEt2
0.5
0.5
1.0
1.0
1.0
1.0
1.0
0.1
1.0
1.0
0.1
1.0
1.0
1.0
0.1
1.0
1.0
1.0
1.0
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
TOLc
MeCN
THF
DCM
DCM
DCM
DCM
DCM
DCM
DCM
DCM
20
20
ꢀ40
ꢀ40
ꢀ40
20
ꢀ40
ꢀ40
ꢀ40
ꢀ40
ꢀ40
20
ꢀ40
ꢀ40
ꢀ40
20
75 (62 : 38)
52 (69 : 31)
90 (65 : 35)
77 (59 : 41)
69 (55 : 45)
67 (43 : 57)
89 (81 : 19)
98 (34 : 66)
34 (86 : 14)
90 (60 : 40)
56 (28 : 72)
76 (57 : 43)
97 (59 : 41)
67 (38 : 62)
62 (38 : 62)
53 (22 : 78)
88 (32 : 68)
83 (34 : 66)
88 (33 : 67)
4a nBu2BOTf
4a nBu2BOTf
4a nBu2BOTf
4a nBu2BOTf
4a nBu2BOTf
4a nBu2BOTf
TfOH
TfOH
4b nBu2BOTf
4b nBu2BOTf
4a
4a
4b
4b
4b
4b
TMSOTf
TMSOTf
TfOH
ꢀ40
20
ꢀ40
TfOH
a Isolated yields. b The glycosylation products were identified, and the α/β ratio
was determined by 1HꢀNMR of the crude reaction mixture. c toluene.
Thus, we envisaged that the TES protected hydroxyl group in 4a could react with the
acetoxy ether group intramolecularly. Gratifyingly, in the first round screening study, the
ringꢀclosing reaction of 4a proceeded smoothly upon the treatment with various types of
Lewis acids, affording 6a with varied yields and stereoselectivities (entry 1ꢀ11, Table 1).
Generally, nBu2BOTf and TMSOTf gave better results than other Lewis acids in term of
the isolated yield. To our surprise, a stoichiometric amount of strong Brønsted acid TfOH,
which was usually considered to be destructive to the glycosidic bond, also gave good
yields for the cyclization (entry 12ꢀ13, Table 1). Using DCM as solvent at lower
temperature gave good yields, while other solvents and higher temperature led to partial
decomposition. However, the stereoselectivity was not very obvious at this point,
depending on the activator, solvent, temperature, and even the activator loading.
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This result prompted us to conduct the second round screening using a more advanced
substrate 4b toward a real disaccharide. This time, all of the three selected activators
(nBu2BOTf, TMSOTf, and TfOH) gave a similar level of βꢀselectivity (β/α, ~ 2/1) (entry
14ꢀ19, Table 1), while TfOH provided higher yield at both ꢀ40 oC and room temperature.
Thus, this activator was chosen in the following studies.
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Having established the validity of this approach, we next sought to evaluate the
efficiency of the glycosylation reaction for the construction of more complex
disaccharides. A range of esters 3cꢀ3i were prepared from the glucose or galactose
derived acids, which were esterified with acceptors having varied hydroxyl groups and
protecting groups. In the reductive acetylation of the hindered esters, toluene was used as
the solvent for the DIBALꢀH reduction step, while DCM gave poor conversions. No
significant stereoselectivity was observed in the reduction step, and the αꢀ acetoxy ethers
4cꢀ4i were formed in moderate to good yields (41ꢀ89%) as mixture of diastereomers with
varied ratios.
OBn
OBn
OBn
O
OBn
O
BnO
BnO
O
BnO
BnO
O
O
BnO
BnO
O
BnO
O
OMP
BnO
BnO
BnO
O
BnO
BnO
O
N3
6e
BnO
OMe
BnO
BnO
6b
OMe
BnO
r.t.
-40 o
74% < 5 : > 95
64% < 5 : > 95
r.t.
-40 o
83% 34 : 66
88% 33 : 67
C
6h
C
r.t.
-40 o
99% 17 : 83
76% 17 : 83
C
OBn
OBn
O
OBn
O
OBn
BnO
O
O
BnO
BnO
O
OMP
BnO
BnO
O
BnO
OBn
BnO
OBn
BnO
BnO
BnO
BnO
OMe
6c
6f
O
O
r.t.
-40 o
96% 12 : 88
73% 6 : 94
r.t.
-40 o
64% < 5 : > 95
73% < 5 : > 95
BnO
C
C
O
O
BnO
BnO
O
O
O
OBn
O
OBn
OBn
6i
OBn
O
BnO
BnO
O
O
O
SPh
BnO
BnO
r.t.
-40 o
75% 6 : 94
87% 6 : 94
BnO
O
BnO
BnO
C
BnO
OMe
6d
6g
r.t.
-40 o
79% < 5 : > 95
64% < 5 : > 95
r.t.
-40 o
78% < 5 : > 95
89% < 5 : > 95
C
C
Figure 1. Scope of the ringꢀclosing glycosylation. The isolated yield and α/β ratio are
shown.
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As shown in Figure 1, upon activation with TfOH in DCM, all the precursors 4cꢀ4i
cyclized smoothly and gave rise to the desired disaccharides 6cꢀ6i in good yields. Apart
from the benzyl group, protecting groups such as OMP, azide, acetonide, and
thioglycosides were compatible with our reaction conditions. The esterꢀtype protecting
groups would be potentially affected under the reductive acetylation condition. When
other activators such as TMSOTf and nBu2BOTf were used, only trace amount of
products was obtained together with significant decomposition of the acetoxy ether.
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To our delight, disaccharides 6cꢀ6g containing (1,4), (1,3), and (1,2) linkage gave
much enhanced βꢀselectivity at both low and room temperature, compared to the model
system. It appeared that the acceptor with hindered secondary alcohols promoted high
stereoselectivity. Indeed, for 6h and 6i prepared from galactoseꢀderived acid and primary
C6ꢀOH acceptors, significant βꢀselectivity was also achieved. No relationship between
the stereoselectivity after the ringꢀclosing glycosylation and the diastereomeric ratio of
the acetoxyꢀether group was observed. It is worthwhile to note that orthoester sideꢀ
reactions, often occurring when C2ꢀOꢀacyl donors were used to mediate the βꢀ
glycosylation27, unlikely took place under the current condition.
H
H
O
H
R
O
OTES
O
PGO
O
TES
R
O
R O
OAc
H
TES
A
TfOH
Steric repulsion
O
O
B'
B
Favored
Disfavored
HOAc & TfO
O
TES
OTES
O
O
O
O
O
PGO
O
O
PGO
PGO
R
R
R
B
C
D
1,2-trans
major
TES
OTES
PGO
O
O
PGO
PGO
R
O
O
R
O
O
R
O
O
B'
C'
D'
1,2-cis
minor
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Scheme 3. Postulated mechanism of the ringꢀclosing glycosylation.
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The postulated mechanism for the ringꢀclosing glycosylation was shown in Scheme 3.
As the stereoselectivity of our glycosylation was not associated with the diastereomeric
ratio of the αꢀacetoxy ether group, the SN2 pathway could be likely excluded. However,
at this stage, we cannot rule out the possibility that the αꢀacetoxy ether rapidly racemized
under the acidic conditions and only the most reactive diastereomer led to the β product.
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To test the possibility that the desilylation take places prior to the cyclization, the
silylated ester 3b (counterpart of αꢀacetoxy ether 4b without the potential for the
oxocarbenium cation generation) was subjected to the ringꢀclosing glycosylation
condition (1 equiv. TfOH in DCM at r.t.). The desilylation was observed, but the reaction
was very slow with a 50% conversion after 1 h at room temperature. Thus, we conclude
that it is more likely that the ringꢀclosing precedes the desilylation.
Thus, we propose an oxocarbenium cation based cyclization. Upon activation of the
acetoxy ether A, the oxocarbenium cation intermediate B is formed, in equilibrium with
B′ rotamer. Ringꢀclosing glycosylation via B is more likely to avoid the steric repulsion
between the acceptor part and the substituent at the C2ꢀposition. The nucleophilic attack
of the C5ꢀOꢀsilylated oxygen to the cation lead to the cyclized intermediate C, which can
be converted to the disaccharide product D via irreversible desilylation.
In summary, we developed a 3ꢀstep ringꢀclosing glycosylation procedure that proceeds
via the unconventional intramolecular pathway. This method involved coupling the two
glycosyl counterparts via an ester linkage, which upon DIBALꢀH mediated Rychnovsky's
reductive acetylation afforded an αꢀacetoxy ether moiety; next, on the treatment with
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TfOH, the C5ꢀOꢀsilylated oxygen substituted the acetoxy ether to induce a ringꢀclosing
reaction, realizing the formation of the pyranosidic linkage. Interestingly, the βꢀ
pyranosides were produced with high selectivity from C2ꢀOꢀbenzyl donors without the
aid of acyl groups for neighboring participation. This novel glycosylation offers an
alternative concept for the design of chemical glycosylation procedure.
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Experimental Section
General procedure for the preparation of esters 3aꢀ3i: To the solution of 2aꢀb (1.0
o
eq.) in THF (0.1 mmol/4 mL), H2O2 (20 eq.) was added at 0 C, followed by 1 M LiOH
(aq., 10 eq.). The mixture was warmed gradually to r.t. and stirred at r.t. for 16 h. The
o
mixture was diluted with ethyl acetate, and neutralized by 10% citric acid (aq.) at 0 C.
The organic phase was separated, and washed with water and brine. After being dried
over Na2SO4, the solvent was removed under vacuum, and the residue was purified by
flash chromatography using nꢀhexane/ethyl acetate 5 : 1 to 2 : 1 as eluent. The
corresponding acid was obtained in variable yields (>90% from 2a and ~80% from 2b)
and directly used in the next step to avoid decomposition.
The acid (1.0 eq.) and alcohol (1.0 eq.) were dissolved in anhydrous DCM (1 mmol/10
o
mL). The mixture was cooled to 0 C, then DCC (2.0 eq.) and DMAP (0.50 eq.) were
added sequentially. The white precipitation can be observed within 10 min. The mixture
was sitrred at r.t. for 4 h, and diluted with nꢀhexane. After filtration, the solution was
concentrated under vacuum, and the residue was purified by flash chromatography using
nꢀhexane/ethyl acetate 10 : 1 to 5 : 1 as eluent to afford the pure esters 3aꢀi.
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Cyclohexyl (2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoate (3a):
Yield 82% (178 mg, colorless oil, from 0.29 mmol acid). 1H NMR (400 MHz, CDCl3): δ
= 0.54−0.60 (m, 6H), 0.90 (t, J = 8.0 Hz, 9H), 1.16−1.34 (m, 5H), 1.49−1.52 (m, 1H),
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1.62−1.69 (m, 3H), 1.83−1.86 (m, 1H), 3.43 (dd, J1 = 9.6 Hz, J2 = 5.2 Hz, 1H), 3.71 (dd,
J1 = 9.6 Hz, J2 = 4.8 Hz, 1H), 3.90 (dd, J1 = 7.2 Hz, J2 = 4.0 Hz, 1H), 4.00 (q, J = 4.8 Hz,
1H), 4.13 (dd, J1 = 7.2 Hz, J2 = 3.6 Hz, 1H), 4.27 (d, J = 3.6 Hz, 1H), 4.42 (d, J = 12.0
Hz, 1H), 4.46 (d, J = 12.0 Hz, 1H), 4.48 (d, J = 11.6 Hz, 1H), 4.59 (d, J = 11.6 Hz, 1H),
4.71 (s, 2H), 4.73−4.77 (m, 1H), 4.82 (d, J = 11.2 Hz, 1H), 4.83 (d, J = 11.2 Hz, 1H),
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7.23−7.39 (m, 20H). C NMR (100 MHz, CDCl3): δ = 5.1, 7.0, 23.9, 25.4, 31.7, 31.8,
72.0, 73.1, 73.3, 73.5, 73.7, 75.0, 75.4, 79.5, 80.8, 81.5, 137.6, 138.4, 138.9, 139.2, 170.1.
ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C46H60O7SiNa+ (M+Na+): 775.4001; Found:
775.4011.
Methyl
2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (3b): Yield 75% (802 mg, colorless oil,
from 0.96 mmol acid). 1H NMR (400 MHz, CDCl3): δ = 0.54 (m, 6H), 0.87 (t, J = 8.0 Hz,
9H), 3.22 (s, 3H), 3.35 (dd, J1 = 9.6 Hz, J2 = 3.6 Hz, 1H), 3.40−3.44 (m, 2H), 3.70 (dd, J1
= 9.6 Hz, J2 = 5.2 Hz, 1H), 3.73−3.76 (m, 1H), 3.91−3.96 (m, 2H), 3.98−4.01 (m, 1H),
4.14 (dd, J1 = 7.2 Hz, J2 = 3.6 Hz, 1H), 4.25 (dd, J1 = 11.8 Hz, J2 = 2.2 Hz, 1H),
4.30−4.34 (m, 2H), 4.39−4.44 (m, 4H), 4.48 (d, J = 10.8 Hz, 1H), 4.52 (d, J = 12.0 Hz,
1H), 4.56 (d, J = 11.2 Hz, 1H), 4.66 (d, J = 12.0 Hz, 1H), 4.68 (d, J = 11.2 Hz, 1H), 4.73
(d, J = 11.2 Hz, 1H), 4.76−4.83 (m, 4H), 4.95 (d, J = 11.2 Hz, 1H), 7.16−7.36 (m, 35H).
13C NMR (75 MHz, CDCl3): δ = 5.0, 7.0, 55.2, 63.3, 68.6, 71.8, 73.0, 73.2, 73.3, 73.4,
75.1, 75.2, 75.3, 75.7, 77.9, 79.3, 80.1, 80.5, 81.9, 97.9, 127.38, 127.40, 127.6, 127.76,
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127.79, 127.89, 127.94, 128.0, 128.07, 128.11, 128.18, 128.25, 128.36, 128.41, 128.44,
128.5, 137.5, 138.0, 138.1, 138.3, 138.8, 138.9, 139.2, 170.5. ESIꢀTOFꢀHRꢀMS (m/z):
Calcd. for C68H80O12SiNa+ (M+Na+): 1139.5311; Found: 1139.5307.
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Methyl
2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (3c): Yield 72% (284 mg, colorless oil,
1
from 0.36 mmol acid). H NMR (400 MHz, CDCl3): δ = 0.52−0.58 (m, 6H), 0.89 (t, J =
8.0 Hz, 9H), 3.33−3.44 (m, 3H), 3.37 (s, 3H), 3.62 (dd, J1 = 9.6 Hz, J2 = 3.6 Hz, 1H),
3.66 (dd, J1 = 9.6 Hz, J2 = 4.8 Hz, 1H), 3.78−3.80 (m, 1H), 3.83 (dd, J1 = 6.8 Hz, J2 = 4.4
Hz, 1H), 3.95−4.02 (m, 2H), 4.12−4.20 (m, 3H), 4.27−4.30 (m, 2H), 4.40 (d, J = 12.2 Hz,
1H), 4.43 (d, J = 12.2 Hz, 1H), 4.52 (d, J = 11.2 Hz, 1H), 4.55−4.63 (m, 6H), 4.67 (d, J =
12.4 Hz, 1H), 4.70 (d, J = 12.4 Hz, 1H), 4.93 (d, J = 11.6 Hz, 1H), 5.16 (t, J = 9.6 Hz,
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1H), 7.14−7.31 (m, 35H). C NMR (100 MHz, CDCl3): δ = 5.1, 7.1, 55.4, 68.8, 69.1,
71.0, 71.8, 73.0, 73.1, 73.3, 73.4, 73.5, 74.7, 74.8, 74.9, 79.0, 80.1, 81.5, 97.9, 127.17,
127.19, 127.3, 127.4, 127.6, 127.7, 127.8, 127.9, 128.0, 128.1, 128.2, 128.3, 128.38,
128.43, 128.6, 137.6, 137.9, 138.2, 138.4, 138.8, 138.9, 139.1, 170.2. ESIꢀTOFꢀHRꢀMS
(m/z): Calcd. for C68H80O12SiNa+ (M+Na+): 1139.5311; Found: 1139.5322.
Phenyl
2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀ1ꢀthioꢀβꢀDꢀglucopyranoside (3d): Yield 79% (305 mg,
colorless oil, from 0.31 mmol acid). 1H NMR (400 MHz, CDCl3): δ = 0.52−0.58 (m, 6H),
0.88 (t, J = 8.0 Hz, 9H), 3.39−3.47 (m, 2H), 3.52−3.64 (m, 4H), 3.72 (dd, J1 = 9.6 Hz, J2
= 5.2 Hz, 1H), 3.88 (dd, J1 = 7.2 Hz, J2 = 4.0 Hz, 1H), 3.99 (q, J = 4.8 Hz, 1H),
4.16−4.19 (m, 3H), 4.26−4.29 (m, 2H), 4.41 (d, J = 12.0 Hz, 1H), 4.45 (d, J = 12.0 Hz,
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1H), 4.51 (d, J = 11.2 Hz, 1H), 4.54−4.68 (m, 7H), 4.79 (d, J = 11.6 Hz, 1H), 4.86 (d, J =
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10.4 Hz, 1H), 5.10 (t, J = 9.2 Hz, 1H), 7.15−7.29 (m, 38H), 7.54−7.57 (m, 2H). 13C NMR
(100 MHz, CDCl3): δ = 5.1, 7.1, 69.6, 71.0, 71.8, 72.9, 73.1, 73.2, 73.5, 74.8, 75.0, 75.1,
75.4, 77.9, 79.8, 80.2, 81.0, 81.7, 83.7, 87.5, 127.2, 127.28, 127.32, 127.45, 127.51, 127.6,
127.70, 127.74, 127.9, 127.98, 128.03, 128.2, 128.31, 128.35, 128.46, 128.51, 129.1,
131.8, 133.8, 137.6, 137.8, 138.2, 138.3, 138.5, 138.9, 139.1, 170.2. ESIꢀTOFꢀHRꢀMS
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(m/z): Calcd. for C73H86NO11SSi+ (M+NH4 ): 1212.5685; Found: 1212.5687.
4ꢀMethoxyphenyl
2ꢀdeoxyꢀ2ꢀazidoꢀ3,6ꢀOꢀdibenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀ
tetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoyl]ꢀβꢀDꢀglucopyranoside (3e): Yield 76% (321
mg, colorless oil, from 0.40 mmol acid). 1H NMR (400 MHz, CDCl3): δ = 0.53−0.59 (m,
6H), 0.90 (t, J = 8.0 Hz, 9H), 3.33 (t, J = 9.6 Hz, 1H), 3.39−3.46 (m, 2H), 3.49−3.54 (m,
2H), 3.70−3.79 (m, 2H), 3.76 (s, 3H), 3.91 (dd, J1 = 7.2 Hz, J2 = 4.0 Hz, 1H), 4.01 (dd, J1
= 9.2 Hz, J2 = 5.2 Hz, 1H), 4.16−4.24 (m, 3H), 4.27−4.32 (m, 2H), 4.43 (d, J = 12.0 Hz,
1H), 4.47 (d, J = 12.0 Hz, 1H), 4.54−4.57 (m, 3H), 4.62−4.71 (m, 4H), 4.76 (d, J = 11.6
Hz, 1H), 5.07 (t, J = 9.2 Hz, 1H), 6.77 (d, J = 9.0 Hz, 2H), 7.04 (d, J = 9.0 Hz, 2H),
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7.16−7.34 (m, 30H). C NMR (100 MHz, CDCl3): δ = 5.1, 7.1, 55.8, 65.8, 69.3, 70.8,
71.9, 72.8, 73.1, 73.3, 73.5, 74.1, 74.2, 74.9, 75.1, 79.6, 80.1, 80.2, 81.7, 101.5, 114.7,
118.5, 127.36, 127.39, 127.5, 127.6, 127.7, 127.80, 127.84, 127.9, 128.0, 128.2, 128.3,
128.4, 128.50, 128.52, 137.5, 137.8, 138.3, 138.4, 138.8, 139.1, 151.2, 155.7, 170.2. ESIꢀ
TOFꢀHRꢀMS (m/z): Calcd. for C67H77N3O12SiNa+ (M+Na+): 1166.5169; Found:
1166.5171.
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4ꢀMethoxyphenyl 2,4,6ꢀOꢀtribenzylꢀ3ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀβꢀDꢀgalactopyranoside (3f): Yield 59% (288 mg, colorless oil,
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from 0.40 mmol acid). H NMR (400 MHz, CDCl3): δ = 0.53−0.59 (m, 6H), 0.89 (t, J =
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8.0 Hz, 9H), 3.04 (d, J = 2.8 Hz, 1H), 3.11 (dd, J1 = 8.8 Hz, J2 = 3.2 Hz, 1H), 3.42−3.49
(m, 2H), 3.56 (dd, J1 = 9.6 Hz, J2 = 6.0 Hz, 1H), 3.74 (s, 3H), 3.82 (dd, J1 = 9.6 Hz, J2 =
3.2 Hz, 1H), 3.97 (dd, J1 = 10.4 Hz, J2 = 8.0 Hz, 1H), 3.99−4.03 (m, 3H), 4.08−4.12 (m,
2H), 4.18 (d, J = 12.0 Hz, 1H), 4.31 (d, J = 12.0 Hz, 1H), 4.37 (d, J = 12.4 Hz, 1H), 4.40
(d, J = 12.4 Hz, 1H), 4.43 (d, J = 12.0 Hz, 1H), 4.46 (d, J = 12.0 Hz, 1H), 4.52−4.55 (m,
2H), 4.60 (d, J = 11.6 Hz, 2H), 4.66 (d, J = 11.6 Hz, 1H), 4.78 (d, J = 10.4 Hz, 1H), 4.88
(d, J = 7.6 Hz, 1H), 4.93 (d, J = 11.6 Hz, 1H), 5.09 (dd, J1 = 10.4 Hz, J2 = 2.8 Hz, 1H),
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6.77 (d, J = 9.2 Hz, 2H), 7.01 (d, J = 9.2 Hz, 2H), 7.09−7.34 (m, 35H). C NMR (100
MHz, CDCl3): δ = 5.2, 7.1, 55.7, 69.4, 72.4, 72.6, 73.4, 73.6, 74.1, 74.3, 74.4, 74.5, 74.6,
74.8, 74.9, 80.6, 81.0, 103.1, 114.6, 118.6, 127.4, 127.59, 127.62, 127.68, 127.69, 127.72,
127.8, 127.9, 128.07, 128.13, 128.2, 128.3, 128.36, 128.39, 128.5, 129.0, 137.8, 138.1,
138.2, 138.4, 138.6, 138.7, 151.5, 155.3, 170.3. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for
C74H84O13SiNa+ (M+Na+): 1231.5573; Found: 1231.5593.
Methyl
3,4,6ꢀOꢀtribenzylꢀ2ꢀOꢀ[(2R,3S,4R,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀβꢀDꢀglucopyranoside (3g): Yield 70% (271 mg, colorless oil,
1
from 0.35 mmol acid). H NMR (400 MHz, CDCl3): δ = 0.52−0.58 (m, 6H), 0.89 (t, J =
8.0 Hz, 9H), 3.20 (s, 3H), 3.40 (dd, J1 = 9.6 Hz, J2 = 5.2 Hz, 1H), 3.44−3.47 (m, 1H),
3.54 (t, J = 9.2 Hz, 1H), 3.68−3.75 (m, 4H), 3.89 (dd, J1 = 7.2 Hz, J2 = 4.0 Hz, 1H), 4.01
(q, J = 4.8 Hz, 1H), 4.08 (d, J = 11.2 Hz, 1H), 4.16 (dd, J1 = 7.2 Hz, J2 = 3.2 Hz, 1H),
4.22 (d, J = 7.6 Hz, 1H), 4.24 (d, J = 3.2 Hz, 1H), 4.42 (s, 2H), 4.52 (d, J = 10.8 Hz, 1H),
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4.54 (d, J = 10.8 Hz, 1H), 4.60−4.77 (m, 9H), 5.19 (dd, J1 = 9.2 Hz, J2 = 8.4 Hz, 1H),
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7.12−7.14 (m, 2H), 7.20−7.33 (m, 33H). 13C NMR (100 MHz, CDCl3): δ = 5.1, 7.1, 56.1,
68.8, 72.2, 72.6, 73.2, 73.4, 73.5, 73.7, 74.6, 75.01, 75.04, 75.2, 75.3, 77.9, 79.4, 80.4,
81.8, 83.2, 101.4, 127.3, 127.4, 127.5, 127.7, 127.8, 127.88, 127.92, 127.94, 128.07,
128.10, 128.12, 128.17, 128.25, 128.5, 137.7, 137.9, 138.2, 138.3, 138.4, 138.8, 139.3,
169.1. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C68H80O12SiNa+ (M+Na+): 1139.5311; Found:
1139.5307.
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Methyl
2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ[(2R,3S,4S,5R)ꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (3h): Yield 38% (117 mg, colorless oil,
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from 0.27 mmol acid). H NMR (400 MHz, CDCl3): δ = 0.52−0.59 (m, 6H), 0.89 (t, J =
8.0 Hz, 9H), 3.25 (s, 3H), 3.41 (t, J = 8.4 Hz, 1H), 3.44 (dd, J1 = 9.6 Hz, J2 = 5.6 Hz, 1H),
3.51 (dd, J1 = 9.2 Hz, J2 = 6.4 Hz, 1H), 3.56 (dd, J1 = 9.2 Hz, J2 = 6.0 Hz, 1H), 3.78−3.83
(m, 1H), 3.91 (dd, J1 = 8.4 Hz, J2 = 2.4 Hz, 1H), 3.96 (t, J = 9.2 Hz, 1H), 4.22 (dt, J1 =
8.4 Hz, J2 = 2.4 Hz, 1H), 4.25−4.34 (m, 4H), 4.38 (d, J = 5.6 Hz, 1H), 4.39 (d, J = 9.2 Hz,
1H), 4.44−4.51 (m, 4H), 4.54 (d, J = 12.4 Hz, 1H), 4.58 (d, J = 12.4 Hz, 1H), 4.59 (d, J =
11.2 Hz, 1H), 4.66 (d, J = 11.2 Hz, 1H), 4.72 (d, J = 12.0 Hz, 1H), 4.79 (d, J = 10.8 Hz,
1H), 4.81 (d, J = 11.2 Hz, 2H), 4.97 (d, J = 10.8 Hz, 1H), 4.18−4.34 (m, 35H). 13C NMR
(100 MHz, CDCl3): δ = 5.6, 7.2, 55.3, 63.7, 68.6, 71.4, 72.0, 72.8, 72.9, 73.2, 73.5, 73.6,
75.2, 75.8, 77.9, 78.5, 79.2, 80.2, 82.1, 98.0, 127.3, 127.38, 127.44, 127.6, 127.7, 127.8,
127.96, 128.00, 128.05, 128.1, 128.2, 128.3, 128.4, 128.5, 128.6, 137.9, 138.0, 138.2,
138.3, 138.6, 138.8, 139.0, 171.7. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C68H80O12SiNa+
(M+Na+): 1139.5311; Found: 1139.5301.
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6ꢀOꢀ[(2R,3S,4S,5R)ꢀ2,3,4,6ꢀTetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoyl]ꢀ1,2;3,4ꢀOꢀ
diisopropylideneꢀαꢀDꢀgalactopyranoside (3i): Yield 61% (162 mg, colorless oil, from
0.29 mmol acid). 1H NMR (400 MHz, CDCl3): δ = 0.55−0.61 (m, 6H), 0.91 (t, J = 8.0 Hz,
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9H), 1.24 (s, 3H), 1.30 (s, 3H), 1.39 (s, 3H), 1.46 (s, 3H), 3.50−3.58 (m, 2H), 3.92 (dd, J1
= 8.4 Hz, J2 = 2.4 Hz, 1H), 4.04 (dt, J1 = 6.4 Hz, J2 = 1.6 Hz, 1H), 4.17 (dd, J1 = 7.6 Hz,
J2 = 1.6 Hz, 1H), 4.21−4.32 (m, 5H), 4.34 (d, J = 11.2 Hz, 1H), 4.38 (d, J = 12.4 Hz, 1H),
4.43−4.47 (m, 2H), 4.47 (d, J = 12.0 Hz, 1H), 4.53 (d, J = 12.0 Hz, 1H), 4.56 (dd, J1 =
8.0 Hz, J2 = 2.4 Hz, 1H), 4.63 (d, J = 11.2 Hz, 1H), 4.69 (d, J = 11.2 Hz, 1H), 4.89 (d, J =
11.2 Hz, 1H), 5.52 (d, J = 5.2 Hz, 1H), 7.20−7.32 (m, 18H), 7.36−7.39 (m, 2H). 13C
NMR (100 MHz, CDCl3): δ = 5.5, 7.2, 24.6, 25.0, 26.0, 26.1, 63.6, 65.6, 70.5, 70.7, 70.9,
71.5, 71.9, 72.7, 73.1, 73.7, 78.1, 78.4, 79.1, 96.3, 108.8, 109.6, 127.3, 127.5, 127.6,
127.7, 127.9, 128.18, 128.22, 128.25, 128.32, 128.4, 137.9, 138.2, 138.6, 138.9, 171.6.
ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C52H68O12SiNa+ (M+Na+): 935.4372; Found:
935.4360.
General procedure for the preparation of αꢀacetoxy ethers 4aꢀ4i: The esters 3aꢀi
(1.0 eq.) were dissolved in anhydrous DCM or toluene (3aꢀb in DCM and 3cꢀi in toluene,
0.1 mmol/1 mL). The mixture was cooled to ꢀ78 oC, and DIBALꢀH (1.0 M in hexane, 2.0
eq.) was added dropwise. The mixture was stirred at ꢀ78 oC for 60−100 min (60 min for
3aꢀb and 100 min for 3cꢀi). At this stage, the solution of pyridine (3.0 eq.) and DMAP
o
(2.0 eq.) in DCM (0.1 mmol ester /1 mL) was added dropwise at ꢀ78 C via cannular,
followed by Ac2O (6.0 eq.). The mixture was stirred at ꢀ78 oC for 10 h, and at 0 oC for 30
o
min. The reaction was quenched by saturated NH4Cl (aq.) at 0 C, extracted with ethyl
acetate, and dried over anhydrous Na2SO4. The residue was purified by flash
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chromatography using nꢀhexane/ethyl acetate 10 : 1 to 5 : 1 as eluent. The desired αꢀ
acetoxy ethers 4aꢀi were obtained as mixture of diastereomers.
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(2R,3S,4R,5R)ꢀ1ꢀcyclohexyloxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀtriethylsiloxyhexyl
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acetate (4a): Yield 91% (187 mg, colorless oil, from 0.26 mmol 3a) as the 1.8 : 1
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mixture of two inseparable diastereomers. H NMR (500 MHz, CDCl3, mixture of
isomers): δ = 0.49−0.57 (m, 6H), 0.83−0.88 (m, 9H), 1.05−1.28 (m, 6H), 1.39−1.44 (m,
1H), 1.54−1.76 (m, 3H), 1.88 (s, 1.1H, minor isomer), 1.89 (s, 1.9 H, major isomer),
3.35−3.39 (m, 0.36H, minor isomer), 3.42 (dd, J1 = 10.0 Hz, J2 = 6.0 Hz, 0.64H, major
isomer), 3.45 (dd, J1 = 10.0 Hz, J2 = 5.5 Hz, 0.36H, minor isomer), 3.53−3.59 (m, 0.64H,
major isomer), 3.64−3.69 (m, 2H), 3.75 (q, J = 5.5 Hz, 1H), 3.82 (t, J = 5.5 Hz, 0.64H,
major isomer), 3.87 (dd, J1 = 5.5 Hz, J2 = 4.5 Hz, 0.36 H, minor isomer), 3.98−4.02 (m,
1H), 4.36−4.41 (m, 2H), 4.49 (d, J = 11.0 Hz, 0.64H, major isomer), 4.55−4.69 (m,
4.36H), 4.74 (d, J = 11.5 Hz, 0.36H, minor isomer), 4.79 (d, J = 11.5 Hz, 0.64H, major
isomer), 6.15 (d, J = 5.0 Hz, 0.64H, major isomer), 6.21 (d, J = 6.5 Hz, 0.36H, minor
isomer), 7.12−7.25 (m, 20H). 13C NMR (125 MHz, CDCl3, mixture of isomers): δ = 5.27,
5.28, 7.1, 21.47, 21.53, 24.0, 24.1, 24.4, 25.66, 25.68, 32.0, 32.3, 33.4, 33.6, 72.58, 72.60,
73.3, 74.08, 74.13, 74.4, 74.46, 74.53, 74.6, 75.0, 75.1, 78.2, 78.3, 78.9, 79.8, 80.7, 81.0,
81.2, 95.4, 95.6, 127.3, 127.35, 127.37, 127.45, 127.51, 127.53, 127.7, 127.78, 127.82,
127.9, 128.0, 128.1, 128.21, 128.24, 128.29, 128.33, 128.4, 128.5, 138.56, 138.59, 138.7,
138.9, 139.1, 139.2, 170.6, 170.9. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C48H64O8SiNa+
(M+Na+): 819.4263; Found: 819.4259.
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Methyl 2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (4b): Yield 91% (529 mg, colorless oil,
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from 0.50 mmol 3b) as the 10.6 : 1 mixture of two inseparable diastereomers. H NMR
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(400 MHz, CDCl3, mixture of isomers): δ = 0.57−0.63 (m, 6H), 0.90 (t, J = 7.6 Hz, 0.78H,
minor isomer), 0.91 (t, J = 8.0 Hz, 8.22H, major isomer), 1.80 (s, 2.74H, major isomer),
1.90 (s, 0.26H, minor isomer), 3.26 (s, 2.74H, major isomer), 3.28 (s, 0.26H, minor
isomer), 3.40 (dd, J1 = 9.6 Hz, J2 = 3.6 Hz, 1H), 3.46 (dd, J1 = 9.6 Hz, J2 = 5.6 Hz, 1H),
3.55 (dd, J1 = 10.0 Hz, J2 = 8.8 Hz, 1H), 3.61−3.68 (m, 2.74H), 3.74−3.77 (m, 0.26H,
minor isomer), 3.81−3.98 (m, 5H), 4.04−4.07 (m, 1H), 4.40−4.44 (m, 2H), 4.48 (d, J =
3.6 Hz, 1H), 4.53−4.86 (m, 11H), 4.94 (d, J = 11.2 Hz, 1H), 6.19 (d, J = 6.8 Hz, 0.09H,
minor isomer), 6.24 (d, J = 6.4 Hz, 0.91H, major isomer), 7.17−7.32 (m, 35H). 13C NMR
(100 MHz, CDCl3, selected peaks of major isomer): δ = 5.1, 7.1, 21.1, 55.1, 68.3, 69.5,
72.3, 73.3, 73.4, 74.0, 74.3, 74.7, 75.0, 75.2, 75.6, 77.6, 79.8, 80.2, 80.5, 82.0, 97.1, 98.0,
127.3, 127.4, 127.48, 127.52, 127.6, 127.7, 127.8, 127.9, 128.0, 128.1, 128.17, 128.24,
128.28, 128.35, 128.39, 128.5, 138.2, 138.4, 138.5, 138.7, 139.06, 139.11, 139.3, 171.0.
ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C70H84O13SiNa+ (M+Na+): 1183.5573; Found:
1183.5568.
Methyl 2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (4c): Yield 57% (168 mg, colorless oil,
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from 0.25 mmol 3c) as the 1.3 : 1 mixture of two inseparable diastereomers. H NMR
(400 MHz, CDCl3, mixture of isomers): δ = 0.53−0.59 (m, 2.61H, minor isomer),
0.60−0.66 (m, 3.39H, major isomer), 0.91 (t, J = 8.0 Hz, 3.91H, minor isomer), 0.94 (t, J
= 8.0 Hz, 5.09H, major isomer), 1.55 (s, 1.70H, major isomer), 1.69 (s, 1.30H, minor
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isomer), 3.29 (s, 1.70H, major isomer), 3.37 (s, 1.30H, minor isomer), 3.48−3.54 (m, 3H),
3.64−3.73 (m, 3H), 3.76−3.82 (m, 3H), 3.91 (t, J = 6.0 Hz, 0.57H, major isomer),
3.97−4.06 (m, 1.43H), 4.11−4.16 (m, 1H), 4.28 (d, J = 12.4 Hz, 0.57H, major isomer),
4.35 (d, J = 10.4 Hz, 0.43H, minor isomer), 4.40 (d, J = 12.4 Hz, 0.57H, major isomer),
4.42−4.45 (m, 2H), 4.48−4.62 (m, 6H), 4.65 (d, J = 10.0 Hz, 0.57H, major isomer),
4.69−4.84 (m, 2.86H), 4.89ꢀ4.92 (m, 2H), 6.32 (d, J = 6.4 Hz, 0.57H, major isomer), 6.62
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(d, J = 2.8 Hz, 0.43H, minor isomer), 7.08−7.32 (m, 33.57H), 7.39−7.41 (m, 1.43H). 13C
NMR (100 MHz, CDCl3, mixture of isomers): δ = 5.2, 5.4, 7.1, 7.2, 21.0, 21.1, 55.3, 55.4,
67.9, 68.9, 69.6, 70.3, 72.3, 73.0, 73.2, 73.30, 73.34, 73.4, 73.6, 73.7, 73.8, 74.3, 74.4,
74.6, 74.9, 75.3, 75.7, 77.9, 78.4, 78.5, 79.4, 79.8, 80.0, 80.1, 80.5, 80.8, 81.39, 81.44,
96.8, 97.6, 98.0, 98.1, 126.8, 127.0, 127.1, 127.2, 127.28, 127.30, 127.32, 127.34, 127.4,
127.49, 127.51, 127.6, 127.66, 127.68, 127.69, 127.8, 127.86, 127.93, 128.12, 128.13,
128.19, 128.21, 128.23, 128.27, 128.33, 128.35, 128.4, 128.46, 128.47, 128.49, 138.1,
138.2, 138.3, 138.40, 138.44, 138.48, 138.52, 138.9, 139.10, 139.15, 139.2, 139.6, 170.3,
170.5. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C70H84O13SiNa+ (M+Na+): 1183.5573; Found:
1183.5565.
Phenyl 2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀ1ꢀthioꢀβꢀDꢀglucopyranoside (4d): Yield 84% (131 mg,
colorless oil, from 0.13 mmol 3d) as the 2.3 : 1 mixture of two inseparable diastereomers.
1H NMR (400 MHz, CDCl3, mixture of isomers): δ = 0.48−0.64 (m, 6H), 0.89 (t, J = 8.0
Hz, 6.27H, major isomer), 0.92 (t, J = 8.0 Hz, 2.73H, minor isomer), 1.57 (s, 0.91H,
minor isomer), 1.75 (s, 2.09H, major isomer), 3.25−3.28 (m, 0.30H, minor isomer),
3.41−3.54 (m, 3H), 3.64−3.85 (m, 6.40H), 3.91 (t, J = 6.4 Hz, 0.30H, minor isomer), 3.95
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(dd, J1 = 7.2 Hz, J2 = 3.6 Hz, 0.70H, major isomer), 4.04 (q, J = 4.8 Hz, 0.30H, minor
isomer), 4.11−4.17 (m, 1H), 4.34 (d, J = 12.0 Hz, 0.30H, minor isomer), 4.39−4.44 (m,
2.70H), 4.47−4.66 (m, 7H), 4.69−4.86 (m, 4H), 4.90 (d, J = 12.0 Hz, 0.70H, major
isomer), 4.96 (d, J = 11.2 Hz, 0.30H, minor isomer), 6.34 (d, J = 6.0 Hz, 0.30H, minor
isomer), 6.56 (d, J = 3.2 Hz, 0.70H, major isomer), 7.06−7.37 (m, 38H), 7.52−7.57 (m,
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2H). C NMR (100 MHz, CDCl3, mixture of isomers): δ = 5.2, 5.4, 7.1, 7.2, 21.0, 21.1,
68.5, 69.0, 72.3, 72.9, 73.2, 73.3, 73.36, 73.38, 73.42, 73.8, 74.05, 74.09, 74.2, 74.5, 74.7,
74.9, 75.0, 75.2, 75.6, 75.9, 78.0, 78.4, 78.6, 78.7, 79.3, 79.5, 80.1, 80.6, 80.86, 80.90,
81.5, 85.2, 86.0, 87.4, 87.5, 96.8, 97.3, 126.8, 127.20, 127.25, 127.3, 127.4, 127.48,
127.51, 127.6, 127.67, 127.74, 127.8, 127.88, 127.92, 128.15, 128.24, 128.3, 128.35,
128.38, 128.41, 128.97, 129.04, 131.8, 131.9, 133.8, 134.1, 138.0, 138.17, 138.21, 138.3,
138.4, 138.5, 138.62, 138.65, 138.75, 138.82, 139.03, 139.06, 139.2, 170.4, 170.5. ESIꢀ
+
TOFꢀHRꢀMS (m/z): Calcd. for C75H90NO12SSi+ (M+NH4 ): 1256.5953; Found:
1256.5945.
4ꢀMethoxyphenyl 2ꢀdeoxyꢀ2ꢀazidoꢀ3,6ꢀOꢀdibenzylꢀ4ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ
2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoyl]ꢀβꢀDꢀglucopyranoside (4e): Yield
74% (123 mg, colorless oil, from 0.14 mmol 3e) as the 6.1 : 1 mixture of two inseparable
1
diastereomers. H NMR (400 MHz, CDCl3, mixture of isomers): δ = 0.52−0.66 (m, 6H),
0.91 (t, J = 8.0 Hz, 7.73H, major isomer), 0.96 (t, J = 8.0 Hz, 1.27H, minor isomer), 1.63
(s, 0.42H, minor isomer), 1.79 (s, 2.58H, major isomer), 3.26−3.33 (m, 0.28H, minor
isomer), 3.39−3.46 (m, 1.72H, major isomer), 3.54 (dd, J1 = 10.0 Hz, J2 = 6.0 Hz, 1H),
3.61−3.72 (m, 3H), 3.75 (s, 0.42H, minor isomer), 3.76 (s, 2.58H, major isomer),
3.79−3.86 (m, 3.86H), 3.95 (dd, J1 = 6.8 Hz, J2 = 3.6 Hz, 1H), 4.03−4.07 (m, 0.14H,
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minor isomer), 4.13−4.16 (m, 1H), 4.30−4.40 (m, 0.56H, minor isomer), 4.42 (s, 1.72H,
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major isomer), 4.45−4.60 (m, 5H), 4.62−4.71 (m, 2.72H), 4.74−4.84 (m, 2.84H), 4.94 (d,
J = 11.2 Hz, 0.14H, minor isomer), 6.34 (d, J = 6.4 Hz, 0.14H, minor isomer), 6.50 (d, J
= 3.2 Hz, 0.86H, major isomer), 6.76 (d, J = 8.8 Hz, 0.28H, minor isomer), 6.79 (d, J =
8.8 Hz, 1.72H, major isomer), 7.01 (d, J = 8.8 Hz, 0.28H, minor isomer), 7.03 (d, J = 8.8
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Hz, 1.72H, major isomer), 7.13−7.43 (m, 30H). C NMR (100 MHz, CDCl3, selected
peaks of major isomer): δ = 5.4, 7.2, 21.1, 55.8, 65.7, 68.7, 72.9, 73.4, 73.5, 73.8, 73.9,
74.1, 74.3, 74.97, 75.04, 78.3, 79.4, 81.5, 82.4, 97.3, 101.7, 114.7, 118.7, 127.3, 127.4,
127.5, 127.59, 127.64, 127.7, 127.8, 127.9, 128.2, 128.25, 128.28, 128.38, 128.42, 138.2,
138.4, 138.5, 138.8, 139.0, 151.3, 155.7, 170.3. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for
C69H85N4O13Si+ (M+NH4 ): 1205.5882; Found: 1205.5878.
+
4ꢀMethoxyphenyl
2,4,6ꢀOꢀtribenzylꢀ3ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀ
tetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoyl]ꢀβꢀDꢀgalactopyranoside (4f): Yield 84%
(154 mg, colorless oil, from 0.15 mmol 3f) as the 2.3 : 1 mixture of two inseparable
1
diastereomers. H NMR (400 MHz, CDCl3, mixture of isomers): δ = 0.55−0.66 (m, 6H),
0.95 (t, J = 8.0 Hz, 6.27H, major isomer), 0.96(t, J = 8.0 Hz, 2.73H, minor isomer), 1.59
(s, 2.09H, major isomer), 2.04 (s, 0.91H, minor isomer), 3.47 (dd, J1 = 10.0 Hz, J2 = 6.4
Hz, 0.30H, minor isomer), 3.52−3.57 (m, 1.40H), 3.59−3.73 (m, 2.60H), 3.77−3.81 (m,
0.70H, major isomer), 3.79 (s, 0.91H, minor isomer), 3.80 (s, 2.09H, major isomer),
3.85−4.05 (m, 5H), 4.11−4.14 (m, 0.30H, minor isomer), 4.15 (dd, J1 = 7.2 Hz, J2 = 3.2
Hz, 0.70H, major isomer), 4.20 (dd, J1 = 9.6 Hz, J2 = 3.2 Hz, 0.30H, minor isomer),
4.23−4.27 (m, 0.70H, major isomer), 4.40−4.50 (m, 5H), 4.58−4.68 (m, 2.40H),
4.73−4.78 (m, 1.70H), 4.81−4.87 (m, 3.30H), 4.91 (d, J = 10.4 Hz, 0.30H, minor isomer),
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4.92 (d, J = 10.8 Hz, 1H), 4.97 (d, J = 12.0 Hz, 1H), 5.11 (d, J = 11.6 Hz, 0.30H, minor
isomer), 6.27 (d, J = 2.0 Hz, 0.70H, major isomer), 6.61 (d, J = 5.6 Hz, 0.30H, minor
isomer), 6.79 (d, J = 9.2 Hz, 0.61H, minor isomer), 6.82 (d, J = 9.2 Hz, 1.39H, major
isomer), 6.99 (d, J = 9.2 Hz, 0.61H, minor isomer), 7.04 (d, J = 9.2 Hz, 1.39H, major
isomer), 7.09−7.44 (m, 35H). 13C NMR (100 MHz, CDCl3, mixture of isomers): δ = 5.2,
5.3, 7.16, 7.21, 21.0, 21.5, 55.7, 68.91, 68.94, 72.6, 73.0, 73.3, 73.37, 73.39, 73.5, 73.6,
73.7, 73.8, 73.9, 74.3, 74.4, 74.5, 74.9, 74.97, 75.03, 75.1, 75.6, 75.7, 78.0, 78.1, 78.4,
79.5, 80.4, 80.5, 80.9, 81.5, 81.8, 82.3, 95.7, 98.6, 102.9, 103.3, 114.5, 118.36, 118.44,
127.2, 127.30, 127.32, 127.4, 127.48, 127.55, 127.59, 127.66, 127.71, 127.78, 128.85,
127.90, 127.94, 128.11, 128.14, 128.16, 128.19, 128.21, 128.26, 128.34, 128.37, 128.40,
128.5, 138.1, 138.3, 138.41, 138.44, 138.5, 138.6, 138.7, 138.79, 138.85, 138.90, 139.0,
139.3, 151.5, 151.8, 155.16, 155.19, 170.6, 171.5. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for
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C76H92NO14Si+ (M+NH4 ): 1270.6287; Found: 1270.6275.
+
Methyl 3,4,6ꢀOꢀtribenzylꢀ2ꢀOꢀ[(2R,3S,4R,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀβꢀDꢀglucopyranoside (4g): Yield 41% (69 mg, colorless oil,
from 0.14 mmol 3g) as the 7.6 : 1 mixture of two partially separable diastereomers. The
1
major diastereomer can be obtained in pure form. H NMR (400 MHz, CDCl3, selected
peaks of major isomer): δ = 0.52−0.63 (m, 6H), 0.90 (t, J = 8.0 Hz, 9H), 1.68 (s, 3H),
3.26 (s, 3H), 3.31−3.35 (m, 1H), 3.47 (t, J = 9.2 Hz, 1H), 3.50 (dd, J1 = 10.0 Hz, J2 = 6.0
Hz, 1H), 3.57 (t, J = 9.2 Hz, 1H), 3.66 (dd, J1 = 10.8 Hz, J2 = 4.4 Hz, 1H), 3.68−3.73 (m,
2H), 3.76−3.81 (m, 2H), 3.93 (dd, J1 = 6.4 Hz, J2 = 4.0 Hz, 1H), 3.97 (dd, J1 = 6.4 Hz, J2
= 3.6 Hz, 1H), 4.08 (d, J = 8.0 Hz, 1H), 4.16 (dt, J1 = 5.6 Hz, J2 = 2.0 Hz, 1H), 4.40 (s,
2H), 4.50 (d, J = 10.4 Hz, 1H), 4.53 (d, J = 12.4 Hz, 1H), 4.61 (d, J = 12.4 Hz, 1H),
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4.69−4.82 (m, 7H), 4.90 (d, J = 11.2 Hz, 1H), 4.99 (d, J = 11.2 Hz, 1H), 6.42 (d, J = 4.4
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Hz, 1H), 7.11−7.13 (m, 2H), 7.20−7.37 (m, 33H). C NMR (100 MHz, CDCl3, selected
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peaks of major isomer): δ = 5.4, 7.2, 21.0, 56.7, 68.8, 72.8, 73.3, 73.5, 73.6, 73.7, 74.9,
75.0, 75.19, 75.21, 75.7, 77.8, 79.2, 80.8, 80.9, 81.0, 84.0, 96.8, 103.7, 127.30, 127.34,
127.49, 127.52, 127.6, 127.67, 127.72, 127.77, 127.81, 127.85, 127.91, 128.02, 128.05,
128.26, 128.28, 128.32, 128.4, 128.5, 138.21, 138.24, 138.4, 138.8, 138.95, 139.02, 139.1,
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+
170.7. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C70H88NO13Si+ (M+NH4 ): 1178.6025; Found:
1178.6028.
Methyl 2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ[(2R,3S,4S,5R)ꢀ1ꢀacetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀ
triethylsiloxyhexanoyl]ꢀαꢀDꢀglucopyranoside (4h): Yield 87% (99 mg, colorless oil,
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from 0.10 mmol 3h) as a single diastereomer. H NMR (400 MHz, CDCl3): δ =
0.55−0.62 (m, 6H), 0.91 (t, J = 8.0 Hz, 9H), 1.76 (s, 3H), 3.31 (s, 3H), 3.46 (dd, J1 = 9.6
Hz, J2 = 3.6 Hz, 1H), 3.53−3.59 (m, 2H), 3.61−3.64 (m, 1H), 3.65 (dd, J1 = 9.6 Hz, J2 =
4.8 Hz, 1H), 3.67−3.71 (m, 1H), 3.86−3.97 (m, 4H), 4.05 (dd, J1 = 6.8 Hz, J2 = 3.2 Hz,
1H), 4.21−4.24 (m, 1H), 4.41 (d, J = 12.0 Hz, 1H), 4.47 (d, J = 12.0 Hz, 1H), 4.54 (d, J =
3.6 Hz, 1H), 4.58−4.64 (m, 4H), 4.67−4.75 (m, 5H), 4.80 (d, J = 10.0 Hz, 1H), 4.83 (d, J
= 10.0 Hz, 1H), 4.95 (d, J = 10.8 Hz, 1H), 6.21 (d, J = 6.4 Hz, 1H), 7.21−7.34 (m, 35H).
13C NMR (100 MHz, CDCl3): δ = 5.5, 7.2, 21.0, 55.2, 68.1, 69.6, 72.4, 72.6, 72.8, 73.2,
73.5, 73.7, 74.2, 75.0, 75.8, 77.6, 78.2, 78.5, 79.7, 80.3, 82.2, 97.0, 98.1, 127.31, 127.35,
127.5, 127.58, 127.60, 127.62, 127.7, 127.8, 127.9, 128.1, 128.30, 128.33, 128.38, 128.43,
128.48, 128.51, 138.28, 138.32, 138.5, 139.00, 139.02, 139.1, 171.0. ESIꢀTOFꢀHRꢀMS
+
(m/z): Calcd. for C70H88NO13Si+ (M+NH4 ): 1178.6025; Found: 1178.6022.
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6ꢀOꢀ[(2R,3S,4S,5R)ꢀ1ꢀAcetoxyꢀ2,3,4,6ꢀtetrabenzyloxyꢀ5ꢀtriethylsiloxyhexanoyl]ꢀ
1,2;3,4ꢀOꢀdiisopropylideneꢀαꢀDꢀgalactopyranoside (4i): Yield 83% (140 mg, colorless
oil, from 0.17 mmol 3i) as the >20 : 1 mixture of two inseparable diastereomers. 1H NMR
(400 MHz, CDCl3, selected peaks of major isomer): δ = 0.57−0.64 (m, 6H), 0.93 (t, J =
8.0 H, 9H), 1.21 (s, 3H), 1.30 (s, 3H), 1.35 (s, 3H), 1.51 (s, 3H), 1.93 (s, 3H), 3.57 (dd, J1
= 9.6 Hz, J2 = 6.8 Hz, 1H), 3.65 (dd, J1 = 9.6 Hz, J2 = 4.4 Hz, 1H), 3.68−3.73 (m, 2H),
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3.86 (dd, J1 = 6.4 Hz, J2 = 3.2 Hz, 1H), 3.90−3.93 (m, 1H), 3.95 (dd, J1 = 6.4 Hz, J2 = 3.2
Hz, 1H), 4.04 (dd, J1 = 6.4 Hz, J2 = 3.2 Hz, 1H), 4.20 (dd, J1 = 8.0 Hz, J2 = 1.2 Hz, 1H),
4.21−4.26 (m, 1H), 4.29 (dd, J1 = 4.8 Hz, J2 = 2.4 Hz, 1H), 4.43 (d, J = 12.0 Hz, 1H),
4.49 (d, J = 12.0 Hz, 1H), 4.56 (dd, J1 = 8.0 Hz, J2 = 2.0 Hz, 1H), 4.61 (s, 2H), 4.66 (d, J
= 12.0 Hz, 1H), 4.70 (d, J = 11.6 Hz, 1H), 4.72 (d, J = 11.6 Hz, 1H), 4.73 (d, J = 11.6 Hz,
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1H), 5.49 (d, J = 5.2 Hz, 1H), 6.24 (d, J = 6.4 Hz, 1H), 7.20−7.38 (m, 20H). C NMR
(75 MHz, CDCl3, selected peaks of major isomer): δ = 5.5, 7.2, 21.2, 24.6, 25.0, 26.1,
26.2, 66.3, 67.5, 70.7, 70.8, 72.6, 72.7, 73.0, 73.3, 73.8, 74.2, 78.1, 78.8, 79.4, 96.4, 96.7,
108.7, 109.4, 127.3, 127.4, 127.5, 127.6, 127.7, 127.8, 128.0, 128.30, 128.33, 128.4,
138.4, 139.0, 139.07, 139.10, 170.8. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C54H76NO13Si+
+
(M+NH4 ): 974.5080; Found: 974.5081.
General procedure for intramolecular glycosylation: The αꢀacetoxy ether 4aꢀi (1.0
eq.) was dissolved in DCM (0.010 mmol/1 mL), and molecular sieves 4Å (100 mg/1 mL
DCM) was added. The mixture was stirred at r.t. for 1 h, then the temperature was
o
adjusted to the designated value (r.t. or ꢀ40 C). TfOH (1.0 eq.) was added, and the
o
mixture was stirred at the same temperature for 0.5 h (at r.t.) to 2 h (at ꢀ40 C). The
reaction was quenched by Et3N, and the product was purified by flash chromatography on
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silica gel using nꢀhexane/ethyl acetate 6 : 1 to 4 : 1 as eluent. The desired disaccharides
6aꢀi were obtained as mixture of α/β anomers. The α/β ratio was determined by 1H NMR
of the mixture. The ratios and yields under different temperatures were shown in Figure 1.
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Cyclohexyl 2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀglucopyranoside (6a): H NMR (400 MHz,
CDCl3, βꢀanomer): δ = 1.22−1.33 (m, 3H), 1.39−1.54 (m, 3H), 1.72−1.78 (m, 2H),
1.92−2.03 (m, 2H), 3.45 (dd, J1 = 8.8 Hz, J2 = 8.0 Hz, 1H), 3.45−3.48 (m, 1H), 3.54 (t, J
= 9.2 Hz, 1H), 3.61−3.67 (m, 2H), 3.68−3.72 (m, 1H), 3.74 (dd, J1 = 10.8 Hz, J2 = 1.6 Hz,
1H), 4.51 (d, J = 8.0 Hz, 1H), 4.53 (d, J = 11.2 Hz, 1H), 4.56 (d, J = 12.0 Hz, 1H), 4.61
(d, J = 12.0 Hz, 1H), 4.71 (d, J = 10.8 Hz, 1H), 4.78 (d, J = 11.2 Hz, 1H), 4.82 (d, J =
10.8 Hz, 1H), 4.92 (d, J = 10.8 Hz, 1H), 5.00 (d, J = 10.8 Hz, 1H), 7.16−7.18 (m, 2H),
7.24−7.36 (m, 18H). 13C NMR (100 MHz, CDCl3, βꢀanomer): δ = 24.1, 24.2, 25.8, 32.2,
33.9, 69.3, 73.5, 74.9, 75.0, 75.1, 75.8, 78.1, 82.4, 85.0, 102.1, 127.66, 127.70, 127.77,
127.82, 127.9, 128.0, 128.2, 128.4, 128.46, 128.49, 128.52, 138.2, 138.4, 138.6, 138.8.28
Methyl
2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀglucopyranosyl)ꢀαꢀDꢀ
glucopyranoside (6b): 1H NMR (400 MHz, CDCl3, βꢀanomer): δ = 3.32 (s, 3H),
3.41−3.45 (m, 1H), 3.46−3.53 (m, 3H), 3.56 (t, J = 9.2 Hz, 1H), 3.63 (t, J = 9.0 Hz, 1H),
3.66−3.74 (m, 3H), 3.81−3.84 (m, 1H), 3.99 (t, J = 9.2 Hz, 1H), 4.18 (dd, J1 = 10.8 Hz, J2
= 1.6 Hz, 1H), 4.35 (d, J = 7.6 Hz, 1H), 4.49−4.54 (m, 3H), 4.56 (d, J = 12.0 Hz, 1H),
4.60 (d, J = 3.6 Hz, 1H), 4.65 (d, J = 12.4 Hz, 1H), 4.71 (d, J = 11.2 Hz, 1H), 4.75 (d, J =
11.2 Hz, 1H), 4.76−4.82 (m, 4H), 4.91 (d, J = 10.8 Hz, 1H), 4.96 (d, J = 10.8 Hz, 1H),
4.97 (d, J = 11.2 Hz, 1H), 7.15−7.35 (m, 35H). 13C NMR (100 MHz, CDCl3, βꢀanomer):
δ = 55.3, 68.7, 69.1, 69.9, 73.49, 73.54, 75.0, 75.1, 75.8, 75.9, 78.0, 78.1, 78.8, 82.1, 82.2,
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84.9, 98.2, 103.9, 127.6, 127.67, 127.71, 127.74, 127.8, 127.9, 127.98, 128.01, 128.04,
128.08, 128.10, 128.3, 128.46, 128.49, 128.52, 128.6, 138.18, 138.23, 138.3, 138.4, 138.5,
138.6, 138.9.29
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Methyl
2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀglucopyranosyl)ꢀαꢀDꢀ
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glucopyranoside (6c): H NMR (400 MHz, CDCl3, βꢀanomer): δ = 3.28−3.31 (m, 1H),
3.34−3.38 (m, 1H), 3.36 (s, 3H), 3.44−3.50 (m, 3H), 3.54 (dd, J1 = 10.8 Hz, J2 = 4.4 Hz,
1H), 3.57−3.62 (m, 2H), 3.70−3.72 (m, 1H), 3.82−3.85 (m, 1H), 3.85 (t, J = 9.6 Hz, 1H),
3.97 (t, J = 9.6 Hz, 1H), 4.36−4.40 (m, 3H), 4.44 (d, J = 12.0 Hz, 1H), 4.54−4.61 (m, 4H),
4.72−4.82 (m, 6H), 4.87 (d, J = 10.8 Hz, 1H), 5.09 (d, J = 11.6 Hz, 1H), 7.17−7.30 (m,
13
33H), 7.40−7.42 (m, 2H). C NMR (100 MHz, CDCl3, βꢀanomer): δ = 55.4, 68.0, 69.1,
70.1, 73.5, 73.7, 74.9, 75.0, 75.3, 75.5, 75.7, 76.7, 78.2, 79.0, 80.5, 82.9, 85.0, 98.5, 102.6,
127.2, 127.4, 127.61, 127.64, 127.68, 127.74, 127.8, 127.9, 128.08, 128.10, 128.12, 128.2,
128.3, 128.4, 128.6, 138.0, 138.4, 138.5, 138.68, 138.72, 139.7.29
Phenyl 2,3,6ꢀOꢀtribenzylꢀ4ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀglucopyranosyl)ꢀ1ꢀthioꢀβꢀ
Dꢀglucopyranoside (6d): 1H NMR (400 MHz, CDCl3, βꢀanomer): δ = 3.31−3.41 (m, 3H),
3.44 (t, J = 9.2 Hz, 1H), 3.54−3.59 (m, 2H), 3.62−3.66 (m, 2H), 3.70 (dd, J1 = 10.8 Hz, J2
= 1.6 Hz, 1H), 3.75 (dd, J1 = 10.8 Hz, J2 = 1.6 Hz, 1H), 3.85 (dd, J1 = 10.8 Hz, J2 = 4.4
Hz, 1H), 4.04 (t, J = 9.6 Hz, 1H), 4.39 (s, 2H), 4.46 (d, J = 12.0 Hz, 1H), 4.52 (d, J = 7.6
Hz, 1H), 4.54 (d, J = 10.8 Hz, 1H), 4.56 (d, J = 11.6 Hz, 1H), 4.63 (d, J = 9.6 Hz, 1H),
4.69−4.75 (m, 4H), 4.78−4.82 (m, 3H), 4.89 (d, J = 10.8 Hz, 1H), 5.14 (d, J = 11.2 Hz,
1H), 7.15−7.36 (m, 38H), 7.54−7.57 (m, 2H). 13C NMR (100 MHz, CDCl3, βꢀanomer): δ
= 68.3, 69.0, 73.3, 73.4, 75.0, 75.2, 75.5, 75.6, 75.8, 76.6, 78.1, 79.4, 80.2, 82.9, 85.06,
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85.11, 87.5, 102.7, 127.4, 127.50, 127.53, 127.6, 127.7, 127.82, 127.84, 127.9, 128.0,
128.1, 128.2, 128.35, 128.38, 128.43, 128.47, 128.50, 129.0, 132.2, 133.8, 138.30, 138.32,
138.4, 138.48, 138.54, 138.7, 139.2.30
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4ꢀMethoxyphenyl 2ꢀdeoxyꢀ2ꢀazidoꢀ3,6ꢀOꢀdibenzylꢀ4ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀ
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glucopyranosyl)ꢀ1ꢀβꢀDꢀglucopyranoside (6e): H NMR (400 MHz, CDCl3, βꢀanomer):
δ = 3.34 (dd, J1 = 9.6 Hz, J2 = 3.2 Hz, 1H), 3.39−3.43 (m, 3H), 3.54−3.65 (m, 4H),
3.68−3.74 (m, 2H), 3.75 (s, 3H), 3.83 (dd, J1 = 10.8 Hz, J2 = 4.0 Hz, 1H), 4.06 (t, J = 9.2
Hz, 1H), 4.40 (s, 2H), 4.44 (d, J = 12.0 Hz, 1H), 4.50 (d, J = 7.6 Hz, 1H), 4.55 (d, J =
12.0 Hz, 1H), 4.56 (d, J = 10.8 Hz, 1H), 4.66 (d, J = 8.4 Hz, 1H), 4.74−4.83 (m, 5H),
4.89 (d, J = 11.2 Hz, 1H), 5.10 (d, J = 11.2 Hz, 1H), 6.79 (d, J = 8.8 Hz, 2H), 7.03 (d, J =
13
8.8 Hz, 2H), 7.17−7.30 (m, 28H), 7.42−7.44 (m, 2H). C NMR (100 MHz, CDCl3, βꢀ
anomer): δ = 55.7, 65.8, 67.9, 69.0, 73.38, 73.43, 75.0, 75.1, 75.17, 75.22, 75.5, 75.8,
76.4, 78.1, 81.1, 82.9, 85.0, 101.6, 102.7, 114.6, 118.8, 127.5, 127.58, 127.61, 127.7,
127.8, 127.87, 127.90, 127.93, 128.26, 128.34, 128.4, 128.5, 138.1, 138.3, 138.4, 138.5,
138.59, 138.62, 151.3, 155.7. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C61H63N3O11Na+
(M+Na+): 1036.4355; Found: 1036.4355.
4ꢀMethoxyphenyl
2,4,6ꢀOꢀtribenzylꢀ3ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀ
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glucopyranosyl)ꢀ1ꢀβꢀDꢀgalactopyranoside (6f): H NMR (400 MHz, CDCl3, βꢀanomer):
δ = 3.38−3.40 (m, 1H), 3.48 (t, J = 8.0 Hz, 1H), 3.58 (dd, J1 = 9.2 Hz, J2 = 6.4 Hz, 1H),
3.61−3.71 (m, 6H), 3.74 (s, 3H), 3.98 (dd, J1 = 9.6 Hz, J2 = 3.2 Hz, 1H), 4.02−4.03 (m,
1H), 4.09 (dd, J1 = 9.6 Hz, J2 = 7.6 Hz, 1H), 4.39 (d, J = 11.6 Hz, 1H), 4.45 (d, J = 11.6
Hz, 1H), 4.50 (d, J = 12.4 Hz, 1H), 4.55−4.63 (m, 3H), 4.72 (d, J = 12.0 Hz, 1H),
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4.79−4.88 (m, 5H), 4.92 (d, J = 7.6 Hz, 1H), 4.98 (d, J = 11.2 Hz, 1H), 5.05 (d, J = 11.2
Hz, 1H), 5.07 (d, J = 11.2 Hz, 1H), 6.77 (d, J = 9.2 Hz, 2H), 7.01 (d, J = 9.2 Hz, 2H),
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7.16−7.32 (m, 33H), 7.38−7.40 (m, 2H). C NMR (100 MHz, CDCl3, βꢀanomer): δ =
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55.7, 68.9, 69.1, 73.4, 73.7, 74.0, 74.7, 74.9, 75.0, 75.16, 75.17, 75.8, 76.2, 78.0, 79.3,
80.0, 82.8, 84.7, 103.2, 103.9, 114.5, 118.6, 127.5, 127.6, 127.68, 127.71, 127.8, 127.9,
128.0, 128.1, 128.25, 128.32, 128.34, 128.48, 128.51, 138.1, 138.2, 138.3, 138.4, 138.5,
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+
138.7, 138.8, 151.7, 155.2. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C68H74NO12 (M+NH4 ):
1096.5206; Found: 1096.5210.
Methyl
3,4,6ꢀOꢀtribenzylꢀ2ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀglucopyranosyl)ꢀβꢀDꢀ
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glucopyranoside (6g): H NMR (400 MHz, CDCl3, βꢀanomer): δ = 3.36−3.39 (m, 1H),
3.46−3.52 (m, 2H), 3.50 (s, 3H), 3.57 (t, J = 9.2 Hz, 1H), 3.63−3.76 (m, 7H), 3.86 (t, J =
8.0 Hz, 1H), 4.40 (d, J = 7.6 Hz, 1H), 4.54−4.58 (m, 4H), 4.63 (d, J = 12.0 Hz, 1H), 4.65
(d, J = 12.0 Hz, 1H), 4.72 (d, J = 11.2 Hz, 1H), 4.74 (d, J = 10.4 Hz, 1H), 4.77−4.81 (m,
3H), 4.86 (d, J = 10.8 Hz, 1H), 4.89 (d, J = 11.6 Hz, 1H), 4.90 (d, J = 7.6 Hz, 1H), 4.97
13
(d, J = 11.2 Hz, 1H), 7.14−7.36 (m, 35H). C NMR (100 MHz, CDCl3, βꢀanomer): δ =
56.2, 68.8, 69.0, 73.6, 73.7, 75.0, 75.05, 75.06, 75.09, 75.3, 75.7, 78.0, 78.2, 78.3, 82.8,
85.0, 85.6, 102.4, 102.5, 127.5, 127.61, 127.62, 127.66, 127.71, 127.8, 127.88, 127.91,
127.98, 128.03, 128.2, 128.3, 128.4, 128.48, 128.50, 128.54, 138.1, 138.2, 138.3, 138.4,
138.5, 138.67, 138.73. ESIꢀTOFꢀHRꢀMS (m/z): Calcd. for C62H66O11Na+ (M+Na+):
1009.4497; Found: 1009.4491.
Methyl 2,3,4ꢀOꢀtribenzylꢀ6ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀgalactopyranosyl)ꢀαꢀDꢀ
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glucopyranoside (6h): H NMR (400 MHz, CDCl3, βꢀanomer): δ = 3.29 (s, 3H), 3.46 (t,
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J = 10.0 Hz, 1H), 3.47−3.52 (m, 3H), 3.54−3.63 (m, 3H), 3.80−3.89 (m, 3H), 3.97 (t, J =
9.2 Hz, 1H), 4.14 (d, J = 10.4 Hz, 1H), 4.30 (d, J = 7.6 Hz, 1H), 4.39 (d, J = 11.6 Hz, 1H),
4.43 (d, J = 11.6 Hz, 1H), 4.50 (d, J = 11.2 Hz, 1H), 4.57 (d, J = 12.0 Hz, 1H), 4.58 (d, J
= 2.8 Hz, 1H), 4.64 (d, J = 12.0 Hz, 1H), 4.69−4.78 (m, 6H), 4.91−4.97 (m, 3H),
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7.15−7.35 (m, 35H). C NMR (100 MHz, CDCl3, βꢀanomer): δ = 55.3, 68.66, 68.74,
70.0, 73.0, 73.4, 73.5, 73.6, 74.7, 74.9, 75.3, 75.8, 78.2, 79.4, 80.0, 82.1, 82.4, 98.0, 104.3,
127.5, 127.57, 127.63, 127.8, 127.9, 128.0, 128.06, 128.10, 128.2, 128.3, 128.39, 128.43,
128.45, 128.54, 138.0, 138.3, 138.5, 138.6, 138.8, 138.9, 139.0.29
6ꢀOꢀ(2,3,4,6ꢀOꢀtetrabenzylꢀβꢀDꢀgalactopyranosyl)ꢀ1,2;3,4ꢀOꢀdiisopropylideneꢀαꢀDꢀ
galactopyranoside (6i): 1H NMR (400 MHz, CDCl3, βꢀanomer): δ = 1.30 (s, 6H), 1.43 (s,
3H), 1.48 (s, 3H), 3.48−3.58 (m, 4H), 3.69 (dd, J1 = 10.4 Hz, J2 = 7.6 Hz, 1H), 3.82 (dd,
J1 = 9.6 Hz, J2 = 7.6 Hz, 1H), 3.88 (d, J = 2.8 Hz, 1H), 4.06−4.09 (m, 1H), 4.13 (dd, J1 =
10.4 Hz, J2 = 3.6 Hz, 1H), 4.21 (dd, J1 = 8.0 Hz, J2 = 1.6 Hz, 1H), 4.30 (dd, J1 = 4.8 Hz,
J2 = 2.4 Hz, 1H), 4.39 (d, J = 12.0 Hz, 1H), 4.41 (d, J = 7.6 Hz, 1H), 4.43 (d, J = 12.0 Hz,
1H), 4.57 (dd, J1 = 8.0 Hz, J2 = 2.4 Hz, 1H), 4.60 (d, J = 11.6 Hz, 1H), 4.70 (d, J = 12.0
Hz, 1H), 4.73 (d, J = 10.8 Hz, 1H), 4.78 (d, J = 12.0 Hz, 1H), 4.92 (d, J = 11.6 Hz, 1H),
5.05 (d, J = 10.8 Hz, 1H), 5.56 (d, J = 4.8 Hz, 1H), 7.23−7.36 (m, 18H), 7.43−7.46 (m,
13
2H). C NMR (100 MHz, CDCl3, βꢀanomer): δ = 24.5, 25.2, 26.10, 26.14, 67.5, 68.8,
69.7, 70.6, 70.9, 71.6, 73.2, 73.4, 73.6, 73.7, 74.6, 74.9, 79.2, 82.0, 96.5, 104.8, 108.7,
109.4, 127.4, 127.6, 127.9, 128.0, 128.2, 128.4, 128.50, 128.52, 128.7, 138.0, 138.75,
138.77, 139.1.31
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1H and C NMR spectra for compounds 3aꢀi, 4aꢀi, and 6aꢀi. This material is available
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Author Information
Corresponding author
Eꢀmail: xuechenl@hku.hk
Note
The authors declare no competing financial interest.
Acknowledgement
The work was supported by the National Basic Research Program of China (973
Program, 2013CB836900), the Area of Excellence Scheme of the University Grants
Committee (AoE/Mꢀ12/06) and Seed Funding from The University of Hong Kong
(201210159054).
References
(1) For leading reviews, see: (a) Carbohydrate-based Drug Discovery; Wong, C.ꢀH. Eds.;
WileyꢀVCH, Weinheim, 2003. (b) Seeberger, P. H.; Werz, D. B. Nature, 2007, 446,
1046−1051. (c) Galonic, D. P.; Gin, D. Y. Nature, 2007, 446, 1000−1007. (d) Nicolaou,
K. C.; Mitchell, H. J. Angew. Chem. Int. Ed. 2001, 40, 1576−1624.
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