Expedient Synthesis of a Linear Nonadecaarabinofuranoside of the Mycobacterium tuberculosis Cellular Envelope

Article abstract of DOI:10.1002/ejoc.201700712

The synthesis of oligosaccharides is demanding as it requires multiple steps and long reaction sequences. The choice of glycosylation method and protecting groups is very important for the successful synthesis of any oligosaccharide. In this paper, we show that ethynylcyclohexyl carbonate glycosyl donors are excellent for the synthesis of a nonadecasaccharide fragment of the Mycobacterium tuberculosis glycocalyx using a split/react/couple strategy. The synthesis of the target nonadecasaccharide was accomplished using eight different reactions and 23 steps in 6.4 % overall yield.

Full text of DOI:10.1002/ejoc.201700712

DOI: 10.1002/ejoc.201700712
Full Paper
Oligosaccharide Synthesis
Expedient Synthesis of a Linear Nonadecaarabinofuranoside of
the Mycobacterium tuberculosis Cellular Envelope
Bijoyananda Mishra,[a] Sujit Manmode,[a] Ravi Raja Adhikari Panda,[a] and Srinivas Hotha*[a]
Abstract: The synthesis of oligosaccharides is demanding as it nors are excellent for the synthesis of a nonadecasaccharide
requires multiple steps and long reaction sequences. The choice fragment of the Mycobacterium tuberculosis glycocalyx using a
of glycosylation method and protecting groups is very impor- split/react/couple strategy. The synthesis of the target nonadec-
tant for the successful synthesis of any oligosaccharide. In this asaccharide was accomplished using eight different reactions
paper, we show that ethynylcyclohexyl carbonate glycosyl do- and 23 steps in 6.4 % overall yield.
Introduction
Infection by multidrug-resistant (MDR) and extremely drug-
resistant (XDR) strains of Mycobacterium tuberculosis has re-
sulted in an increase in worldwide mortality due to tuberculosis,
and this has led to a growing socioeconomic burden.[1–4] Pa-
tients suffering from tuberculosis have to undergo chemother-
apy for a long period of time; this has been attributed to the
diminished passage of chemotherapeutic agents due to a thick
and waxy cellular envelope.[5] Lipoarabinomannan (LAM) and
arabinogalactan (AG) are the two major structural constituents
of the cell wall of M. tuberculosis, and arabinan is the common
motif in both of these.[6–9] These structural motifs are currently
attracting unprecedented attention for the development of
drugs, vaccines, and diagnostics owing to the xenobiotic status
of the saccharide components: arabinose and galactose are in
the furanosyl form.[10] Mycobacterial arabinan biosynthesis is
arrested in the presence of ethambutol, and so this is pre-
scribed as a drug in combination with others.[11] Mycobacterial
arabinan contains α-Araf-(1→5)-α-Araf, α-Araf-(1→3)-α-Araf and
ꢀ-Araf-(1→2)-α-Araf linkages; α-Araf-(1→5)-α-Araf linkages are
predominant, and terminal α-Araf residues are capped with ꢀ-
Araf-(1→2) linkages.[12–14] In addition, terminal ꢀ-Araf-(1→2)
residues are further esterified with mycolic acid. The synthesis
of arabinan oligosaccharides has received considerable atten-
tion due to their immense significance in disease management.
Several groups have attempted the synthesis of arabinan
Figure 1. Cartoon representation of arabinogalactan (AG) of the M. tuberculo-
sis cell wall, and the target molecule.
motifs;[15–20] a large oligoarabinan with 22 Araf units,[21,22]
a
henicosasaccharide[23] fragment of AG, and a much larger frag-
ment with 92 saccharide residues[24] have been reported (Fig-
ure 1).
Results and Discussion
In this paper, we describe the synthesis of a nonadecaarabino-
furanoside with α-Araf(1→5)-Araf linkages, as found in the ara-
binogalactan of M. tuberculosis, using gold-catalysed glycosyl-
ations.[25–29] We planned to synthesize the nonadecasaccharide
by a split/react/couple strategy in which the glycosyl donor and
the acceptor can both be synthesized from the same precursor.
The precursor saccharide is split into two portions; these then
[a] Department of Chemistry, Indian Institute of Science Education and
Research,
Dr. Homi Bhabha Road, Pune 411008, India
E-mail: s.hotha@iiserpune.ac.in
www.iiserpune.ac.in/~s.hotha
Supporting information for this article is available on the WWW under
https://doi.org/10.1002/ejoc.201700712.
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react individually with appropriate reagents to synthesize a glycosyl donor 10 by Pd-mediated hydrolysis of allyl glycoside
glycosyl donor and acceptor; and finally these are coupled (or followed by conversion into the alkynyl carbonate using rea-
glycosylated) to give the saccharide of interest. This is a power- gent 6 as described above. The second portion was treated
ful approach since it significantly decreases the number of steps with HF·py to give the required acceptor 9 in very good yield.
required for the preparation of the donor and acceptor, and Glycosylation between donor 10 and acceptor 9 gave tetra-
makes the overall synthesis more convergent.
arabinofuranoside 11 in 94 % yield. This was subsequently
transformed into acceptor 12 (Scheme 2).
The glycosylation approach that we have used in this synthe-
sis was reported recently by us. In this approach, alkynyl glyc-
osyl carbonates are activated in the presence of Au/Ag cata-
lysts.[29] The salient features of this protocol are the stable glyc-
osyl donors, consistently high yields, mild reaction conditions,
and catalytic activation; the approach is also compatible with
many of the functional groups found in carbohydrate chemis-
try.[29]
Tetrasaccharide 12 and donor 10 were treated with Au phos-
phite 7 (8 mol-%) and AgOTf (8 mol-%) in CH2Cl2 to give hexa-
saccharide 13 in 92 % yield (Scheme 3). The formation of the
hexasaccharide was confirmed by thorough NMR spectroscopic
analysis and mass spectrometry. In the 1H NMR spectrum, reso-
nances due to the vinylic CH moiety can be seen at δ = 5.93
(dddd, J = 16.5, 10.6, 5.9, 5.1 Hz, 1 H) ppm, and the protons of
Our exploration started with the synthesis of key arabino- the tert-butyl group of the TBDPS group resonate at δ = 1.01
furanoside derivative 1. -Arabinose was first locked into the (s, 9 H) ppm. Six anomeric protons of hexasaccharide 13 were
D
furanosyl form through glycosylation under acidic conditions identified by six individual singlets at δ = 5.27, 5.35, 5.39, 5.39,
using allyl alcohol and a catalytic amount of acetyl chloride. 5.40, and 5.41 ppm, and other resonances were also in com-
This gave an allyl furanoside, which was subsequently protected plete agreement with the structure of hexasaccharide 13. In the
at the C-5 position using TBDPS-Cl (tert-butyldiphenylsilyl chlor- 13C NMR spectrum of compound 13, resonances due to the six
ide) and imidazole at room temperature. The remaining second- anomeric carbon atoms can be seen at δ = 104.9, 105.8, 105.9,
ary hydroxy groups were converted into benzoates by treat- 105.9, 106.0, and 106.0 ppm; the vinylic carbon atoms resonate
ment with BzCl in pyridine. Having obtained the key substrate, at δ = 117.5 (CH2) and 133.8 (CH) ppm; twelve signals due to
compound 2 was split into two portions. The first portion was the twelve carbonyl carbon atoms of the benzoate groups can
treated with PdCl2 in CH3OH/CH2Cl2 (3:1) to give hemiacetal 3 be seen from δ = 165.2 to 165.8 ppm. In addition, the structure
in 90 % yield. This was then treated with carbonate 6 and DMAP of hexasaccharide 13 was further confirmed by HRMS (calcd.
[4-(dimethylamino)pyridine] to give glycosyl donor 4 in 96 % for C133H120O37SiNa 2360.7209; found 2360.7206).[30]
yield. For the second portion of compound 2, cleavage of the
TBDPS ether was carried out with HF·py to give glycosyl ac-
ceptor 5 in 92 % yield (Scheme 1).
The successful synthesis of glycosyl donor 4 and acceptor 5
encouraged us to go ahead with the coupling (or glycosylation).
Furanosylation between donor 4 and acceptor 5 was success-
fully carried out in the presence of gold phosphite 7 (8 mol-%)
and AgOTf (8 mol-%) in CH2Cl2 for 15 min to give the disacchar-
ide 8 in excellent yield.
In continuation, hexasaccharide 13 was again split into two
portions; the first portion was converted into alkynyl glycosyl
carbonate donor 14, and the second portion was transformed
into glycosyl acceptor 15 by treatment with HF·py. Hexasac-
charide donor 14 and hexasaccharide acceptor 15 were sub-
jected to standard Au/Ag-catalysed furanosylation conditions to
give dodecasaccharide 16 in 96 % yield. Cleavage of the silyl
ether of dodecasaccharide 16 gave glycosyl acceptor 17. This
was then subjected to glycosylation with hexasaccharide donor
Continuing our split/react/couple strategy, disaccharide 8 14 to give octadecaarabinofuranoside 18. For the synthesis of
was split into two portions. The first portion was converted into the nonadecaarabinofuranoside, one more arabinofuranoside
Scheme 1. Synthesis of the monosaccharide units.
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Scheme 2. Synthesis of the tetrasaccharide.
had to be added at the nonreducing end of compound 18.
Hence, fluoride-mediated cleavage of the silyl ether followed
by the glycosylation using donor 4 gave the desired nonadeca-
saccharide 19. The structure of nonadecasaccharide 19 was
thoroughly confirmed by NMR spectroscopy and mass spec-
1
trometry. In the H NMR spectrum of nonadecasaccharide 19,
resonances due to anomeric protons were identified at δ ≈
5.41–5.48 ppm, and the presence of the allyl moiety was dem-
onstrated by the olefinic CH signal at δ = 6.01 (dddd, J = 16.5,
10.7, 5.8, 5.2 Hz, 1 H) ppm. Furthermore, the 13C NMR spectrum
of compound 19 showed signals of all the anomeric carbon
atoms at δ ≈ 104.8–106.0 ppm. Additional confirmation was
obtained by MS studies (calcd. for C380H328O115SiNa 6784.9619;
found 6784.8623).
Cleavage of the silyl ether gave polysaccharide 20, and sa-
ponification under Zemplén conditions gave the fully depro-
tected allyl nonadecaarabinofuranoside 21 in 67 % over two
steps as a fluffy white powder. The global deprotection was
confirmed by the complete disappearance of signals in both
aliphatic and aromatic regions of the NMR spectra of 21. The
Scheme 3. Synthesis of the nonadecaarabinofuranoside.
anomeric signals of nonadecasaccharide 21 were identified at
1
δ = 5.07–5.09 ppm in the H NMR spectrum and at δ = 107.1– adduct of nonadecasaccharide 21 was observed at m/z =
108.0 ppm in the 13C NMR spectrum. Furthermore, the sodium 2590.1692 (calcd. for C98H158O77Na 2590.8379).[30]
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ers were dried with anhydrous Na2SO4 and concentrated in vacuo.
The resulting crude residue was purified by silica gel column chro-
matography to give compound 2 (8.70 g, 90 %).
Conclusions
We have described the total synthesis of a linear nonadeca-
arabinofuranoside fragment of the mycobacterial cell-wall com-
ponent arabinogalactan. Key features of our strategy were the
preparation of the glycosyl donor and acceptor from the same
precursor, and repetition of this approach, resulting in a highly
convergent synthesis. The strategy implemented in this synthe-
sis is quite general, and can be invoked for the facile synthesis
of other linear and branched oligosaccharides. Biophysical ex-
periments are currently underway, and the results will be re-
ported in due course.
2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α/ꢀ-D-arabino-
furanose (3): Compound 2 (5.00 g, 7.85 mmol) was dissolved in a
mixture of CH3OH/CH2Cl2 (3:1; 30 mL), and a solution of PdCl2
(278.5 mg, 1.57 mmol) in CH3OH (5 mL) was added dropwise. The
mixture was stirred at 25 °C. After 3 h, the reaction was quenched
by the addition of excess triethylamine, and the mixture was con-
centrated in vacuo. The residue was purified by silica gel column
chromatography using ethyl acetate/petroleum ether as mobile
phase to give compound 3 (4.22 g, 90 %) as a pale yellow solid.
The same procedure was also used in the synthesis of compounds
10 and 14.
Experimental Section
Synthesis of Donors 4, 10, and 14: DMAP (1.23 g, 10.05 mmol)
was added to a solution of hemiacetal 3 (5.0 g, 8.38 mmol) in anhy-
drous CH2Cl2 (40 mL), and the mixture was stirred for 20 min. Rea-
gent 6[29] (2.91 g, 10.05 mmol) was added portionwise (3 ×) after
every 30 min, and the mixture was then stirred at 25 °C for 1 h. The
mixture was concentrated in vacuo, and the oily residue was par-
tially purified by silica gel column chromatography (n-hexane/
EtOAc). Fractions containing compound 4 along with trace amounts
of 4-nitrophenol were concentrated under reduced pressure. The
crude residue was dissolved in CH2Cl2 (30 mL), and this solution
was washed with satd. aq. NaHCO3 (20 mL) to remove the 4-nitro-
phenol. This gave alkynyl arabinofuranosyl donor 4 (6.00 g, 96 %)
as a fluffy white solid.
General Methods: Unless otherwise noted, materials were ob-
tained from commercial suppliers and used without further purifica-
tion. 1-Ethynylcyclohexanol, p-nitrophenyl chloroformate, and all
metal salts were purchased from Sigma–Aldrich. Unless otherwise
noted, all reactions were carried out under nitrogen. Removal of
solvents in vacuo refers to distillation using a rotary evaporator at-
tached to an efficient vacuum pump. Products obtained as solids
or syrups were dried under high vacuum. Analytical thin-layer chro-
matography was carried out on precoated silica plates (F254
,
0.25 mm thickness); compounds were visualized by UV light or by
staining with anisaldehyde spray. Optical rotations were measured
with a digital polarimeter. IR spectra were recorded with an FTIR
spectrometer. Unless otherwise noted, NMR spectra were recorded
with a 400, 500, or 600 MHz instrument with CDCl3 as the solvent
and tetramethylsilane as the internal standard. High-resolution
mass spectrometry (HRMS) was carried out with an ESI-MS or
MALDI-TOF mass spectrometer. Low-resolution mass spectra (LRMS)
were obtained with a UPLC-MS instrument with a TLC interface.
The same procedure was also used for the synthesis of alkynyl carb-
onate donors 10 and 14.
Allyl 2,3-Di-O-benzoyl-α-D-arabinofuranoside (5): Silyl ether 2
(7.0 g, 10.99 mmol) was dissolved in a mixture of THF and pyridine
(5:1; 50 mL), and HF·Py (2.0 mL) was added at 0 °C. The reaction
mixture was then stirred at 25 °C. After 4 h, the mixture was cooled
to 0 °C, and silica gel (15 g) was added. Filter column chromatogra-
phy was carried out. Compound-containing fractions were concen-
trated under reduced pressure. The resulting residue was then dis-
solved in CH2Cl2 (40 mL), and the solution was washed with HCl
General Procedures
Allyl 5-O-tert-Butyldiphenylsilyl-α-
alcohol (100 mL) was cooled to 0 °C, and acetyl chloride (2.5 mL)
was added. The mixture was stirred for 1 h; then -arabinose (10.0 g,
D-arabinofuranoside (1): Allyl
D
66.6 mmol) was added. The mixture was stirred at 25 °C for a further
1 h, and then it was stirred at 80 °C for a further 5 h. The product
was purified by column chromatography (acetone/CH2Cl2, 6:4) to
(1
N aq.; 20 mL), satd. aq. NaHCO3 (20 mL), and brine (20 mL). The
CH2Cl2 layer was dried with anhydrous Na2SO4, decanted, and con-
centrated in vacuo to give compound 5 (4.03 g, 92 %) as a viscous
syrup.
give allyl α-
D-arabinofuranoside (10.39 g, 82 %) as an off-white solid.
Allyl α- -arabinofuranoside (5.00 g, 26.29 mmol) was dissolved in
D
DMF (30 mL), and imidazole (5.37 g, 78.87 mmol) was added at
25 °C. The mixture was cooled to 0 °C, and TBDPSCl (8.20 mL, 8.67 g,
31.55 mmol) was added dropwise. The reaction mixture was then
stirred at 25 °C. After 4 h, the mixture was diluted with water and
extracted with ethyl acetate (3 × 50 mL). The combined ethyl acet-
ate layers were washed with brine. The organic layer was filtered,
and the filtrate was concentrated in vacuo. The oily residue was
purified by silica gel column chromatography using ethyl acetate
and petroleum ether as the mobile phase to give compound 1
(9.58 g, 85 %).
The same procedure was also used for the synthesis of compounds
9, 12, 15, 17, and 20.
Synthesis of Compounds 8, 11, 13, 16, 18, and 19: AgOTf
(138 mg, 0.54 mmol) and gold phosphite 7 (471 mg, 0.54 mmol)
were added to a solution of donor 5 (5.00 g, 6.69 mmol) and ac-
ceptor 4 (2.67 g, 6.69 mmol) in anhydrous CH2Cl2 (40 mL) contain-
ing powdered molecular sieves (4 Å; 400 mg). The mixture was
stirred at 25 °C for 15 min; then it was concentrated in vacuo. The
resulting residue was purified by silica gel column chromatography
(petroleum ether/EtOAc) to give disaccharide 8 (6.02 g, 92 %) as a
viscous syrup.
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-D-arabino-
furanoside (2): Compound 1 (8.00 g, 18.67 mmol) was dissolved in
pyridine (50 mL), and the solution was cooled to 0 °C. Benzoyl chlor-
ide (5.42 mL, 6.56 g, 46.66 mmol) was added dropwise, and then
the reaction mixture was warmed to 25 °C and stirred for 12 h. The
progress of the reaction and formation of compound 2 were
Synthesis of Compound 21: Compound 20 (120 mg, 18.4 μmol)
was dissolved in CH3OH, and NaOMe (0.5
M solution in CH3OH;
2 mL) was added. The reaction mixture was stirred at 25 °C. After
15 h, the mixture was neutralized with Amberlite IR 120 (H+) resin,
filtered, and concentrated under reduced pressure. The residue was
washed with ethyl acetate (2 × 2 mL) and CH3OH (2 × 2 mL) to give
checked by TLC. The reaction mixture was diluted with HCl (5
N aq.;
100 mL), CH2Cl2 (100 mL) and washed with water, satd. aq. sodium
hydrogen carbonate solution, and brine. The combined organic lay- compound 21 (39 mg, 83 %).
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Compound Characterization Data
1.4 Hz, 1 H), 4.31 (ddt, J = 13.1, 4.9, 1.6 Hz, 1 H), 4.38 (q, J = 4.0 Hz,
1 H), 5.24 (dq, J = 10.4, 1.5 Hz, 1 H), 5.32 (s, 1 H), 5.39 (dq, J = 17.2,
1.7 Hz, 1 H), 5.49 (dd, J = 5.0, 1.4 Hz, 1 H), 5.59 (d, J = 1.4 Hz, 1 H),
5.97 (dddd, J = 16.4, 10.5, 5.9, 5.1 Hz, 1 H), 7.45 (m, 4 H), 7.55–7.62
(m, 2 H), 8.08 (m, 4 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 62.3,
67.9, 77.8, 82.0, 83.8, 104.8, 117.4, 128.5, 128.5, 128.5, 128.5, 129.1,
129.2, 129.9, 129.9, 129.9, 129.9, 133.5, 133.6, 133.7, 165.4,
166.2 ppm. HRMS (ESI-MS): calcd. for [C22H22O7Na]+ 421.1263; found
421.1260.
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-D-arabino-
furanoside (2): M.p. 62.7 °C. [α]D25 = –14.6 (c = 1.0 in CHCl3). IR
(CHCl3): ν = 3068, 2928, 2858, 1727, 1599, 1456, 1268, 1108, 1066,
˜
1
971, 932, 707 cm–1. H NMR (400.31 MHz, CDCl3): δ = 1.05 (s, 9 H),
4.02 (d, J = 4.6 Hz, 2 H), 4.11 (ddt, J = 13.1, 6.0, 1.3 Hz, 1 H), 4.29
(ddt, J = 13.2, 5.0, 1.5 Hz, 1 H), 4.40 (q, J = 4.6 Hz, 1 H), 5.22 (dq,
J = 10.5, 1.3 Hz, 1 H), 5.27 (s, 1 H), 5.37 (dq, J = 17.2, 1.7 Hz, 1 H),
5.49 (d, J = 1.5 Hz, 1 H), 5.62 (d, J = 1.4 Hz, 1 H), 5.96 (dddd, J =
16.5, 10.6, 5.9, 5.1 Hz, 1 H), 7.31–7.41 (m, 8 H), 7.43–7.47 (m, 2 H),
7.54–7.60 (m, 2 H), 7.70–7.73 (m, 4 H), 7.98–8.00 (m, 2 H), 8.05–8.07
(m, 2 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 19.4, 26.8, 26.8,
26.9, 63.7, 67.9, 77.5, 82.6, 83.1, 105.0, 117.4, 127.7, 127.7, 127.7,
127.7, 128.4, 128.4, 128.4, 128.4, 129.3, 129.5, 129.7, 129.7, 130.0,
130.0, 130.0, 130.0, 133.3, 133.4, 133.4, 133.4, 134.0, 135.7, 135.7,
135.7, 135.7, 165.5, 165.7 ppm. HRMS (ESI-MS): calcd. for
[C38H40O7SiNa]+ 659.2441; found 659.2439.
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-D-arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α-D-arabinofuranoside (8):
Syrup. [α]D25 = –7.23 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3068,
˜
2930, 2860, 1724, 1600, 1454, 1356, 1266, 1106, 1065, 1027, 968,
1
707 cm–1. H NMR (400.31 MHz, CDCl3): δ = 1.04 (s, 9 H), 3.96 (dd,
J = 11.2, 2.9 Hz, 2 H), 4.01 (dd, J = 4.4, 1.3 Hz, 1 H), 4.09 (ddt, J =
13.2, 4.9, 1.4 Hz, 1 H), 4.23 (dd, J = 11.2, 4.6 Hz, 1 H), 4.31 (ddt, J =
13.2, 4.9, 1.4 Hz, 1 H), 4.54 (m, 2 H), 5.22 (dd, J = 10.5, 1.3 Hz, 1 H),
5.30 (s, 1 H), 5.37 (dd, J = 17.2, 1.6 Hz, 1 H), 5.41 (s, 1 H), 5.58 (d,
J = 1.1 Hz, 1 H), 5.60 (d, J = 1.1 Hz, 1 H), 5.66 (t, J = 4.9 Hz, 2 H),
5.96 (dddd, J = 16.4, 10.6, 5.9, 5.0 Hz, 1 H), 7.28–7.40 (m, 11 H),
7.40–7.52 (m, 5 H), 7.57 (m, 2 H), 7.69–7.75 (m, 4 H), 7.92–7.97 (m,
2 H), 7.97–8.03 (m, 4 H), 8.05–8.11 (m, 2 H) ppm. 13C NMR
(100.67 MHz, CDCl3): δ = 19.4, 26.9, 26.9, 26.9, 63.5, 66.2, 67.9, 77.5,
77.5, 82.0, 82.0, 82.3, 83.3, 105.0, 106.1, 117.5, 127.8, 127.8, 127.8,
127.8, 128.3, 128.4, 128.5, 128.5, 128.5, 128.6, 128.6, 128.6, 129.1,
129.4, 129.4, 129.4, 129.8, 129.8, 129.9, 129.9, 129.9, 129.9, 130.0,
130.0, 130.1, 130.1, 133.2, 133.3, 133.4, 133.4, 133.5, 133.5, 133.9,
135.8, 135.8, 135.8, 135.8, 165.4, 165.5, 165.6, 165.8 ppm. HRMS (ESI-
MS): calcd. for [C57H56O13SiNa]+ 999.3388; found 999.3389.
2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α/ꢀ-D-arabino-
furanose (3): α/ꢀ = 1:1.1. Syrup. [α]D25 = –41.1 (c = 1.0 in CHCl3). IR
(CHCl3): ν = 3012, 2935, 2860, 1728, 1603, 1455, 1366, 1268, 1107,
˜
1
952, 704 cm–1. H NMR (399.78 MHz, CDCl3): δ = 1.03 (s, 9 H), 1.10
(s, 9 H), 3.42 (d, J = 4.1 Hz, 1 H), 3.91 (dd, J = 11.1, 2.5 Hz, 1 H), 3.97
(dd, J = 4.6, 1.2 Hz, 2 H), 4.06 (dd, J = 11.1, 3.0 Hz, 1 H), 4.22–4.27
(q, J = 4.6 Hz, 1 H), 4.38 (d, J = 10.5 Hz, 1 H), 4.56 (q, J = 4.6 Hz, 1
H), 5.47 (d, J = 1.7 Hz, 1 H), 5.55 (dd, J = 5.6, 4.9 Hz, 1 H), 5.60 (d,
J = 3.7 Hz, 1 H), 5.64 (dd, J = 4.8, 1.5 Hz, 1 H), 5.71 (dd, J = 10.5,
4.8 Hz, 1 H), 6.02 (dd, J = 5.7, 4.1 Hz, 1 H), 7.27–7.46 (m, 20 H), 7.48–
7.59 (m, 4 H), 7.68–7.71 (m, 6 H), 7.78–7.80 (m 2 H), 7.94–7.97 (m, 2
H), 7.99–8.10 (m, 6 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 19.5,
19.5, 26.9, 27.0, 27.0, 27.0, 27.1, 27.1, 63.8, 65.2, 76.6, 77.7, 79.5, 82.8,
83.1, 83.6, 95.6, 101.3, 127.9, 127.9, 127.9, 127.9, 127.9, 127.9, 127.9,
127.9, 128.2, 128.2, 128.6, 128.6, 128.6, 128.6, 128.7, 128.7, 129.3,
129.3, 129.4, 129.5, 129.9, 129.9, 130.0, 130.0, 130.1, 130.1, 130.1,
130.2, 130.3, 130.4, 131.9, 132.2, 133.3, 133.4, 133.6, 133.6, 133.6,
133.6, 133.7, 133.7, 135.7, 135.7, 135.8, 135.8, 135.8, 135.9, 136.1,
136.1, 165.8, 165.8, 166.0, 166.3 ppm. HRMS (ESI-MS): calcd.
for[C35H36O7SiNa]+ 619.2128; found 619.2126.
Allyl 2,3-Di-O-benzoyl-α-
benzoyl-α-
-arabinofuranoside (9): M.p. 120.2 °C. [α]D25 = –20.4
(c = 1.0 in CHCl3). IR (CHCl3): ν = 3524, 3067, 2929, 1718, 1602,
D
-arabinofuranosyl-(1→5)-2,3-di-O-
D
˜
1490, 1453, 1257, 1176, 1106, 1066, 1027, 969, 712 cm–1 1H NMR
.
(400.31 MHz, CDCl3): δ = 2.37 (s, 1 H), 3.91 (dd, J = 11.2, 2.9 Hz, 2
H), 3.96 (dd, J = 13.1, 5.9 Hz, 1 H), 4.02 (dd, J = 13.1, 5.9 Hz, 1 H),
4.14 (dd, J = 11.2, 4.5 Hz, 1 H), 4.21 (dd, J = 13.1, 4.8 Hz, 1 H), 4.38–
4.47 (m, 2 H), 5.13 (d, J = 10.4 Hz, 1 H), 5.22 (s, 1 H), 5.28 (d, J =
11.2 Hz, 1 H), 5.35 (s, 1 H), 5.37 (d, J = 4.5 Hz, 1 H), 5.50 (s, 1 H),
5.57 (d, J = 5.1 Hz, 1 H), 5.59 (s, 1 H), 5.86 (dddd, J = 16.6, 10.4, 5.8,
5.1 Hz, 1 H), 7.21 (m, 2 H), 7.37 (m, 8 H), 7.50 (m, 2 H), 7.87 (m, 2
H), 7.97 (m, 6 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 62.2, 66.0,
67.7, 77.3, 77.7, 81.6, 81.8, 81.8, 83.7, 104.7, 105.7, 117.3, 128.2,
128.2, 128.4, 128.4, 128.4, 128.4, 128.4, 128.4, 128.9, 129.0, 129.1,
129.1, 129.7, 129.7, 129.7, 129.7, 129.8, 129.8, 129.8, 129.8, 133.2,
133.3, 133.4, 133.4, 133.7, 165.0, 165.3, 165.7, 166.0 ppm. HRMS (ESI-
MS): calcd. for [C41H38O13Na]+ 761.2210; found 761.2207.
2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-1-O-{[(1-ethynyl-
cyclohexyl)oxy]carbonyl}-D-arabinofuranose (4): α/ꢀ = 2:1. M.p.
51.4 °C. [α]D25 = –21.0 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3067, 2929,
˜
2857, 1762, 1729, 1598, 1454, 1240, 1108, 1071, 1018, 945, 910, 849,
1
707 cm–1. H NMR (400.31 MHz, CDCl3): δ = 1.03 (s, 9 H), 1.04 (s, 9
H), 1.29–1.40 (m, 3 H), 1.45–1.48 (m, 1 H), 1.49–1.60 (m, 3 H), 1.61–
1.73 (m, 6 H), 1.89–1.97 (m, 3 H), 1.98–2.24 (m, 4 H), 2.37 (s, 1 H),
2.65 (s, 1 H), 3.93–4.02 (m, 4 H), 4.34 (q, J = 5.6 Hz, 1 H), 4.58 (q, J =
4.6 Hz, 1 H), 5.67 (d, J = 1.5 Hz, 1 H), 5.73–5.76 (m, 2 H), 6.11 (dd,
J = 7.2, 6.1 Hz, 1 H), 6.32 (s, 1 H), 6.47 (d, J = 4.6 Hz, 1 H), 7.31–7.48
(m, 20 H), 7.53–7.71 (m, 12 H), 7.94–8.12 (m, 8 H) ppm. 13C NMR
(100.67 MHz, CDCl3): δ = 19.3, 19.4, 22.4, 22.4, 22.6, 22.6, 25.0, 25.1,
26.8, 26.8, 26.8, 26.9, 26.9, 26.9, 36.6, 36.8, 36.8, 36.9, 63.2, 64.7, 74.7,
75.4, 76.6, 76.8, 78.0, 78.4, 81.5, 82.2, 82.6, 82.7, 85.5, 85.5, 97.1,
102.6, 127.8, 127.8, 127.8, 127.8, 127.8, 127.8, 127.8, 127.8, 128.5,
128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.9, 129.1, 129.3,
129.4, 129.8, 129.8, 129.8, 129.8, 130.0, 130.1, 130.1, 130.1, 130.1,
130.1, 130.1, 130.3, 133.1, 133.1, 133.2, 133.2, 133.4, 133.5, 133.5,
133.6, 135.7, 135.7, 135.7, 135.7, 135.8, 135.8, 135.8, 135.8, 151.1,
151.1, 165.2, 165.5, 165.5, 165.6 ppm. HRMS (ESI-MS): calcd. for
[C44H46O9 SiNa]+ 769.2809; found 769.2805.
2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-1-O-{[(1-ethynylcyclo-
hexyl)oxy]carbonyl}-α/ꢀ- -arabinofuranose (10): α/ꢀ = 6:1. M.p.
69.8 °C. [α]D25 = –6.0 (c = 1.0 in CHCl ). IR (CHCl ): ν = 3067, 2935,
D-arabino-
D
˜
3
3
2860, 1760, 1725, 1599, 1453, 1265, 1175, 1106, 1067, 1022, 965,
824, 708 cm–1. H NMR (400.31 MHz, CDCl3): δ = 1.01 (s, 9 H), 1.04
1
(s, 9 H), 1.30–1.40 (m, 1 H), 1.43–1.47 (m, 1 H), 1.50–1.60 (m, 2 H),
1.59–1.79 (m, 8 H), 2.08 (m, 8 H), 2.35 (s, 1 H), 2.66 (s, 1 H), 3.91–
4.06 (m, 6 H), 4.12–4.28 (m, 2 H), 4.49–4.72 (m, 4 H), 5.35–5.39 (m,
2 H), 5.55 (m, 2 H), 5.64–5.72 (m, 2 H), 5.74–5.75 (m, 3 H), 5.78–6.13
(m, 1 H), 6.25–6.90 (m, 2 H), 7.31–7.41 (m, 24 H), 7.42–7.50 (m, 7 H),
7.53–7.61 (m, 5 H), 7.69–7.65 (m, 8 H), 7.94–8.04 (m, 12 H), 8.09–
8.19 (m, 4 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 19.4, 19.4,
22.6, 22.6, 22.7, 22.7, 24.9, 25.1, 26.9, 26.9, 26.9, 26.9, 26.9, 27.0, 36.6,
Allyl 2,3-Di-O-benzoyl-α-
–29.5 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3489, 3068, 2927, 1723, 1603,
D =
-arabinofuranoside (5): Syrup. [α]2D5
˜
1453, 1268, 1110, 1067, 1033, 982, 712 cm–1. H NMR (400.31 MHz, 36.6, 36.8, 36.9, 63.4, 63.5, 65.9, 67.7, 74.9, 75.2, 75.5, 76.3, 76.9, 77.2,
1
CDCl3): δ = 2.70 (s, 1 H), 3.97–4.08 (m, 2 H), 4.13 (ddt, J = 13.1, 5.9, 77.3, 77.4, 78.3, 78.5, 80.9, 81.0, 82.2, 82.6, 82.7, 83.4, 83.6, 84.4, 96.9,
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102.5, 106.0, 106.3, 127.8, 127.8, 127.8, 127.8, 127.8, 127.8, 127.8, ν = 3067, 2933, 2859, 1723, 1602, 1453, 1356, 1266, 1176, 1108,
˜
127.8, 128.4, 128.4, 128.4, 128.5, 128.5, 128.5, 128.5, 128.5, 128.6, 1069, 1027, 966, 709 cm–1
.
1H NMR (400.31 MHz, CDCl3): δ = 1.01
128.6, 128.6, 128.6, 128.7, 128.7, 128.7, 128.7, 128.9, 129.0, 129.3, (s, 9 H), 3.88–3.95 (m, 5 H), 3.95–3.99 (m, 2 H), 4.08 (ddt, J = 13.3,
129.3, 129.3, 129.3, 129.4, 129.6, 129.8, 129.8, 129.8, 129.8, 129.9, 6.0, 1.3 Hz, 1 H), 4.19 (m, 5 H), 4.28 (ddt, J = 13.2, 4.9, 1.5 Hz, 1 H),
129.9, 130.0, 130.0, 130.0, 130.0, 130.0, 130.1, 130.1, 130.1, 130.1, 4.48 (m, 2 H), 4.61 (m, 4 H), 5.20 (dt, J = 10.4, 1.4 Hz, 1 H), 5.27 (s,
130.1, 130.1, 130.1, 130.3, 130.3, 133.2, 133.3, 133.3, 133.3, 133.4, 1 H), 5.34 (dt, J = 10.4, 1.4 Hz, 1 H), 5.35 (s, 1 H), 5.39 (s, 1 H), 5.39
133.4, 133.4, 133.4, 133.6, 133.6, 133.7, 133.7, 135.8, 135.8, 135.8, (s, 1 H), 5.40 (s, 1 H), 5.41 (s, 1 H), 5.55–5.58 (m, 2 H), 5.65 (m, 10
135.8, 135.8, 135.8, 135.8, 135.8, 151.1, 151.1, 165.2, 165.4, 165.4, H), 5.93 (dddd, J = 16.5, 10.6, 5.9, 5.1 Hz, 1 H), 7.18–7.46 (m, 36 H),
165.6, 165.6, 165.7, 165.7, 165.7 ppm. HRMS (ESI-MS): calcd. for
7.46–7.61 (m, 6 H), 7.64–7.75 (m, 4 H), 7.82–7.93 (m, 10 H), 7.95–7.98
(m, 4 H), 8.00–8.06 (m, 10 H) ppm. 13C NMR (100.67 MHz, CDCl3):
δ = 19.4, 26.8, 26.8, 26.8, 63.4, 65.8, 65.9, 65.9, 65.9, 66.0, 67.8, 77.3,
77.3, 77.3, 77.3, 77.4, 77.4, 81.5, 81.6, 81.6, 81.6, 82.0, 82.0, 82.1, 82.2,
82.2, 82.2, 82.2, 83.2, 104.9, 105.8, 105.9, 105.9, 106.0, 106.0, 117.5,
127.7, 127.7, 127.7, 127.8, 127.8, 127.8, 128.3, 128.3, 128.3, 128.3,
128.3, 128.3, 128.3, 128.4, 128.4, 128.4, 128.4, 128.4, 128.4, 128.5,
128.5, 128.5, 128.6, 128.6, 128.6, 128.6, 128.6, 128.6, 128.6, 128.6,
129.1, 129.1, 129.1, 129.1, 129.1, 129.1, 129.2, 129.2, 129.2, 129.3,
129.3, 129.3, 129.7, 129.7, 129.7, 129.8, 129.8, 129.8, 129.8, 129.8,
129.8, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9,
129.9, 129.9, 130.0, 130.0, 130.0, 130.0, 133.1, 133.2, 133.2, 133.2,
133.2, 133.3, 133.3, 133.4, 133.4, 133.4, 133.5, 133.5, 133.5, 133.5,
133.8, 135.7, 135.7, 135.7, 135.7, 165.2, 165.2, 165.2, 165.2, 165.3,
165.5, 165.6, 165.6, 165.7, 165.7, 165.7, 165.8 ppm. HRMS (ESI-MS):
calcd. for [C133H120O37SiNa]+ 2360.7209; found 2360.7206.
[C63H62O15SiNa]+ 1109.3756; found 1109.3752.
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α-
-arabinofuranoside (11): M.p. 65.2 °C. [α]D25 = +6.3 (c =
D-arabino-
D
D
D
1.0 in CHCl3). IR (CHCl3): ν = 3067, 2927, 2858, 1723, 1601, 1454,
˜
1426, 1265, 1176, 1107, 966, 707 cm–1. 1H NMR (400.31 MHz, CDCl3):
δ = 1.09 (s, 9 H), 4.03 (m, 5 H), 4.12–4.19 (m, 1 H), 4.22–4.39 (m, 4
H), 4.57 (m, 2 H), 4.71 (m, 2 H), 5.26 (dd, J = 10.4, 1.4 Hz, 1 H), 5.35
(s, 1 H), 5.42 (dd, J = 17.2, 1.6 Hz, 1 H), 5.47 (s, 1 H), 5.49 (s, 1 H),
5.50 (s, 1 H), 5.65 (d, J = 1.1 Hz, 1 H), 5.66 (d, J = 1.1 Hz, 1 H), 5.69–
5.77 (m, 6 H), 6.00 (dddd, J = 16.5, 10.6, 5.9, 5.1 Hz, 1 H), 7.28–7.51
(m, 25 H), 7.58 (m, 5 H), 7.77 (m, 4 H), 7.94–8.01 (m, 6 H), 8.02–8.07
(m, 4 H), 8.07–8.14 (m, 6 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ =
19.3, 26.8, 26.8, 26.8, 63.5, 65.9, 66.0, 66.0, 67.8, 77.3, 77.4, 77.4, 77.4,
81.6, 81.6, 82.0, 82.0, 82.2, 82.2, 82.2, 83.3, 104.9, 105.9, 106.0, 106.0,
117.4, 127.7, 127.7, 127.7, 127.7, 127.7, 127.7, 128.3, 128.3, 128.3,
128.3, 128.3, 128.3, 128.4, 128.4, 128.5, 128.5, 128.5, 128.5, 128.6,
128.6, 128.6, 128.6, 129.1, 129.1, 129.2, 129.2, 129.2, 129.3, 129.3,
129.3, 129.7, 129.7, 129.8, 129.8, 129.8, 129.8, 129.8, 129.9, 129.9,
129.9, 129.9, 129.9, 129.9, 130.0, 130.0, 130.0, 133.1, 133.2, 133.2,
133.2, 133.3, 133.3, 133.4, 133.4, 133.4, 133.5, 133.8, 135.7, 135.7,
135.7, 135.7, 165.2, 165.2, 165.2, 165.4, 165.5, 165.6, 165.7,
165.7 ppm. HRMS (ESI-MS): calcd. for [C95H88O25SiNa]+ 1680.5315;
found 1680.5317.
2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-1-O-{[(1-eth-
D-arabino-
D
D
D
D-
ynylcyclohexyl)oxy]carbonyl}-α-D-arabinofuranose (14): α/ꢀ =
4:1. M.p. 114.5 °C. [α]D25 = +10.8 (c = 1.0 in CHCl3). IR (CHCl3): ν =
˜
3065, 2936, 2858, 1760, 1725, 1601, 1453, 1269, 1176, 1110, 1069,
1028, 910, 709 cm–1. 1H NMR (400.31 MHz, CDCl3): δ = 1.10 (s, 9 H),
1.10 (s, 9 H), 1.26–1.43 (m, 2 H), 1.52–1.78 (m, 10 H), 1.99 (m, 4 H),
2.27 (m, 4 H), 2.51 (s, 1 H), 2.74 (s, 1 H), 4.05 (m, 14 H), 4.30 (m, 10
H), 4.46–4.82 (m, 12 H), 5.50 (m, 10 H), 5.64–5.80 (m, 21 H), 5.80–
6.70 (m, 5 H), 7.26–7.41 (m, 34 H), 7.47 (m, 37 H), 7.52–7.65 (m, 13
H), 7.78 (m, 8 H), 7.97 (m, 19 H), 8.10 (m, 29 H) ppm. 13C NMR
(100.67 MHz, CDCl3): δ = 19.4, 19.4, 22.6, 22.6, 22.6, 22.6, 24.8, 25.0,
26.8, 26.8, 26.9, 26.9, 26.9, 26.9, 36.6, 36.6, 36.8, 36.9, 63.5, 63.5, 65.8,
65.8, 65.9, 65.9, 65.9, 65.9, 65.9, 65.9, 66.0, 66.0, 74.5, 75.3, 75.6, 76.2,
76.8, 77.2, 77.2, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.4, 77.4, 77.4,
78.3, 78.4, 80.7, 81.0, 81.6, 81.6, 81.6, 81.6, 81.9, 82.2, 82.2, 82.2, 82.2,
82.2, 82.2, 82.3, 82.3, 82.6, 82.6, 83.3, 83.3, 83.3, 83.3, 84.4, 84.4, 96.6,
102.4, 105.7, 106.0, 106.0, 106.0, 106.0, 106.0, 106.0, 106.1, 106.1,
106.1, 127.7–127.8 (12 C), 128.3 (16 C), 128.4 (6 C), 128.5 (4 C), 128.6
(16 C), 128.7 (6 C), 129.1 (10 C), 129.2 (6 C), 129.3 (8 C), 129.7 (4 C),
129.8 (20 C), 129.9 (16 C), 130.0 (6 C), 130.1, 130.2, 133.1 (2 C), 133.2
(8 C), 133.3 (3 C), 133.4 (7 C), 133.5 (3 C), 133.6 (2 C), 133.7 (3 C),
135.7, 135.7, 135.7, 135.7, 135.7, 135.7, 135.7, 135.7, 151.0, 151.1,
165.1 (3 C), 165.2 (9 C), 165.5 (3 C), 165.6 (4 C), 165.7 (4 C),
165.8 ppm. HRMS (ESI-MS): calcd. for [C139H126O39SiNa]+ 2470.7577;
found 2470.7568.
Allyl 2,3-Di-O-benzoyl-α-
D
-arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-D-
D
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-D-arabinofuranos-
ide (12): M.p. 85.1 °C. [α]2D5 = +2.2 (c = 1.0 in CHCl3). IR (CHCl3): ν =
˜
3532, 3067, 2928, 2860, 1722, 1602, 1453, 1266, 1176, 1109, 1068,
1027, 966, 710 cm–1. 1H NMR (400.31 MHz, CDCl3): δ = 2.41 (s, 1 H),
3.98 (m, 5 H), 4.12 (ddt, J = 13.1, 5.9, 1.5 Hz, 1 H), 4.17–4.27 (m, 3
H), 4.31 (ddt, J = 13.1, 4.9, 1.6 Hz, 1 H), 4.50 (m, 2 H), 4.65 (m, 2 H),
5.23 (dd, J = 10.5, 1.4 Hz, 1 H), 5.31 (s, 1 H), 5.38 (dd, J = 17.2, 1.7 Hz,
1 H), 5.42–5.48 (m, 4 H), 5.59 (d, J = 1.4 Hz, 1 H), 5.61–5.72 (m, 6 H),
5.97 (dddd, J = 16.4, 10.5, 5.9, 5.1 Hz, 1 H), 7.22–7.33 (m, 6 H), 7.38–
7.49 (m, 13 H), 7.50–7.63 (m, 5 H), 7.86–7.99 (m, 6 H), 8.00–8.13 (m,
10 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 62.3, 65.9, 65.9, 66.1,
67.8, 77.3, 77.3, 77.3, 77.7, 81.6, 81.6, 81.7, 81.9, 81.9, 82.0, 82.1, 83.7,
104.8, 105.8, 105.9, 105.9, 117.4, 128.3, 128.3, 128.3, 128.3, 128.3,
128.3, 128.4, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5,
128.5, 129.0, 129.0, 129.1, 129.1, 129.1, 129.1, 129.2, 129.3, 129.8,
129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8,
129.8, 129.9, 129.9, 129.9, 129.9, 133.2, 133.2, 133.3, 133.4, 133.4,
133.4, 133.4, 133.5, 133.8, 165.1, 165.2, 165.2, 165.4, 165.7, 165.7,
165.7, 166.1 ppm. HRMS (ESI-MS): calcd. for [C79H70O25Na]+
1441.4104; found 1441.4098.
Allyl 2,3-Di-O-benzoyl-α-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
D
-arabinofuranosyl-(1→5)-2,3-di-O-
D
D-
D
D
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuran-
D-arabino- 2,3-di-O-benzoyl-α-D-arabinofuranoside (15): M.p. 123.2 °C.
D
[α]D25 = +13.3 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3067, 2931,
˜
D
2857, 1721, 1602, 1490, 1453, 1259, 1176, 1106, 1069, 1026, 965,
1
D
D
-
709 cm–1. H NMR (400.31 MHz, CDCl3): δ = 2.60 (s, 1 H), 3.93–4.08
D
(m, 7 H), 4.14 (dd, J = 13.2, 5.9 Hz, 1 H), 4.18–4.40 (m, 6 H), 4.52 (q,
oside (13): M.p. 109.5 °C. [α]D25 = +12.2 (c = 1.0 in CHCl3). IR (CHCl3): J = 4.5 Hz, 2 H), 4.65–4.70 (m, 4 H), 5.24 (dd, J = 17.2, 1.6 Hz, 1 H),
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5.34 (s, 1 H), 5.40 (dd, J = 17.2, 1.6 Hz, 1 H), 5.46–5.48 (m, 6 H), 5.63
(d, J = 1.1 Hz, 1 H), 5.65–5.77 (m, 10 H), 5.98 (dddd, J = 16.6, 10.5,
5.9, 5.1 Hz, 1 H), 7.28 (m, 10 H), 7.44 (m, 20 H), 7.50–7.57 (m, 4 H),
7.59 (m, 2 H), 7.84–8.02 (m, 10 H), 8.08 (m, 14 H) ppm. 13C NMR
5.97 (dddd, J = 16.5, 10.6, 5.8, 5.3 Hz, 1 H), 7.24–7.31 (m, 22 H),
7.40–7.48 (m, 37 H), 7.49–7.63 (m, 13 H), 7.89–7.96 (m, 22 H), 8.02–
8.11 (m, 26 H) ppm. 13C NMR (100.67 MHz, CDCl3): δ = 62.3, 65.8,
65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.9, 66.1, 67.8, 77.2, 77.2,
(100.67 MHz, CDCl3): δ = 62.3, 65.9, 65.9, 65.9, 65.9, 66.1, 67.8, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.3, 77.3, 77.3, 77.7, 81.5, 81.5, 81.5,
77.3, 77.3, 77.3, 77.3, 77.7, 81.6, 81.6, 81.6, 81.6, 81.7, 82.0, 82.0, 82.1,
82.2, 82.2, 82.2, 83.8, 104.8, 105.8, 105.9, 105.9, 105.9, 105.9, 117.4,
81.5, 81.5, 81.5, 81.6, 81.6, 81.6, 81.7, 81.9, 82.0, 82.0, 82.1, 82.1, 82.1,
82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 83.7, 104.8, 105.8, 105.9, 105.9,
128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 128.3, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 117.4, 128.3 (24
128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.5, 128.6, 128.6, C), 128.5 (24 C), 129.0 (2 C), 129.1 (20 C), 129.2, 129.3, 129.8 (40 C),
128.6, 128.6, 128.6, 128.6, 129.0, 129.0, 129.1, 129.1, 129.1, 129.1, 129.9 (8 C), 133.1 (8 C), 133.2 (2 C), 133.3, 133.4 (12 C), 133.5, 133.8,
129.1, 129.1, 129.1, 129.1, 129.2, 129.3, 129.8, 129.8, 129.8, 129.8, 165.1 (10 C), 165.2, 165.4, 165.6 (10 C), 165.7, 166.1 ppm. HRMS
129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.8, 129.9, 129.9, (MALDI-TOF): calcd. for [C231H198O73Na]+ 4164.1746; found
129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 129.9, 4164.4248.
133.2, 133.2, 133.2, 133.2, 133.3, 133.4, 133.4, 133.4, 133.5, 133.5,
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
-arabino- arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
-arabinofuranosyl-(1→5)- furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
-arabinofuranosyl-(1→5)-2,3-di-O- 2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
-arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino- arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)- furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O- 2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino- arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
-arabinofuranosyl-(1→5)-
-arabinofuranoside (18): M.p. 130.8 °C. [α]
D-arabino-
133.5, 133.5, 133.8, 165.1, 165.1, 165.2, 165.2, 165.2, 165.4, 165.6,
165.7, 165.7, 165.7, 165.7, 166.0 ppm. HRMS (ESI-MS): calcd. for
[C117H102O37Na]+ 2122.6031; found 2122.6033.
D
D
D
D-
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α-
2,3-di-O-benzoyl-α-
benzoyl-α-
D
D
D
D
D
D
D
D
-
D
D-
D
D
D
D
D
D
D
D
-
D
D-
D
D
furanosyl-(1→5)-2,3-di-O-benzoyl-α-
D
-arabinofuranoside (16):
furanosyl-(1→5)-2,3-di-O-benzoyl-α-
D
M.p. 125.6 °C. [α]D25 = +15.9 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3066, 2,3-di-O-benzoyl-α-
D
˜
D
2926, 2860, 1723, 1602, 1453, 1267, 1176, 1109, 1070, 1027, 966,
= +23.6 (c = 1.0 in CHCl3). IR (CHCl3): ν = 3067, 2932, 2858, 1722,
˜
25
1
709 cm–1. H NMR (400.31 MHz, CDCl3): δ = 1.04 (s, 9 H), 3.92–4.01 1602, 1490, 1453, 1176, 1069, 1026, 965, 709 cm–1
.
1H NMR
(m, 13 H), 4.05–4.34 (m, 14 H), 4.47–4.66 (m, 12 H), 5.22 (d, J = (400.31 MHz, CDCl3): δ = 1.08 (s, 9 H), 4.00 (m, 19 H), 4.11–4.42 (m,
10.5 Hz, 1 H), 5.30 (s, 1 H), 5.33–5.48 (m, 12 H), 5.56–5.62 (m, 2 H),
5.65–5.70 (m, 21 H), 5.95 (dddd, J = 16.5, 10.4, 5.9, 4.9 Hz, 1 H),
7.21–7.29 (m, 21 H), 7.32–7.46 (m, 45 H), 7.45–7.61 (m, 12 H), 7.70–
7.73 (m, 4 H), 7.87–7.94 (m, 22 H), 7.99–8.07 (m, 26 H) ppm. 13C
NMR (100.67 MHz, CDCl3): δ = 19.4, 26.9, 26.9, 26.9, 63.5, 65.9, 65.9,
65.9, 65.9, 65.9, 65.9, 65.9, 65.9, 66.0, 66.0, 66.0, 67.9, 77.3, 77.3, 77.3,
77.3, 77.3, 77.3, 77.3, 77.3, 77.4, 77.4, 77.4, 77.5, 81.6, 81.6, 81.6, 81.6,
81.6, 81.6, 81.6, 81.7, 81.7, 81.7, 82.0, 82.1, 82.2, 82.2, 82.2, 82.2, 82.2,
82.2, 82.2, 82.2, 82.2, 82.2, 82.3, 83.3, 104.9, 105.9, 106.0, 106.0,
20 H), 4.49–4.78 (m, 18 H), 5.26 (d, J = 10.5 Hz, 1 H), 5.35 (s, 1 H),
5.47 (m, 18 H), 5.65 (m, 2 H), 5.72 (m, 33 H), 6.00 (dddd, J = 16.5,
10.6, 5.9, 5.1 Hz, 1 H), 7.20–7.34 (m, 34 H), 7.35–7.50 (m, 62 H), 7.55
(m, 18 H), 7.76 (m, 4 H), 7.95 (m, 33 H), 8.06 (m, 39 H) ppm. 13C
NMR (100.67 MHz, CDCl3): δ = 19.3, 26.8, 26.8, 26.8, 63.5, 65.8, 65.8,
65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.9, 65.9, 65.9, 65.9, 65.9,
65.9, 66.0, 67.8, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2,
77.2, 77.2, 77.3, 77.3, 77.4, 77.4, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6,
81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 82.0, 82.0, 82.1, 82.1, 82.1, 82.1,
106.0, 106.0, 106.0, 106.0, 106.0, 106.0, 106.1, 106.1, 117.5, 127.8, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1,
127.8, 127.8, 127.8, 128.4 (20 C), 128.5 (4 C), 128.6 (24 C), 129.1 (10
C), 129.2 (12 C), 129.4 (2 C), 129.8 (2 C), 129.9 (32 C), 130.0 (14 C),
130.1 (2 C), 133.2–133.3 (12 C), 133.4–133.5 (14 C), 133.9, 135.8,
135.8, 135.8, 135.8, 165.2 (9 C), 165.3 (2 C), 165.5, 165.6, 165.7 (10
82.1, 82.1, 82.1, 82.1, 83.3, 104.9, 105.9, 105.9, 105.9, 105.9, 105.9,
105.9, 105.9, 105.9, 105.9, 105.9, 106.0, 106.0, 106.0, 106.0, 106.0,
106.0, 106.0, 117.4, 127.7 (6 C), 128.3 (30 C), 128.4 (6 C), 128.5 (36
C), 129.1 (14 C), 129.2 (18 C), 129.3 (4 C), 129.7, 129.7, 129.8 (30 C),
C), 165.8 ppm. HRMS (MALDI-TOF): calcd. for [C247H216O73SiNa]+ 129.9 (38 C), 130.0, 130.0, 133.1 (2 C), 133.2 (16 C), 133.3 (2 C), 133.4
4402.2924; found 4402.4847.
Allyl 2,3-Di-O-benzoyl-α-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α-
-arabinofuranoside (17): M.p. 137.0 °C. [α]D25 = +18.1
(c = 1.0 in CHCl3). IR (CHCl3): ν = 3066, 2927, 2856, 1722, 1602, 1453,
(14 C), 133.5 (4 C), 133.8, 135.7, 135.7, 135.7, 135.7, 165.2 (16 C),
165.4, 165.4, 165.5, 165.5, 165.6 (12 C), 165.7, 165.7, 165.7,
165.7 ppm. HRMS (MALDI-TOF): calcd. for [C361H312O109SiNa]+
6444.8672; found 6446.9458.
D
-arabinofuranosyl-(1→5)-2,3-di-O-
D
D-
D
D
Allyl 2,3-Di-O-benzoyl-5-O-tert-butyldiphenylsilyl-α-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
1176, 1108, 1070, 1027, 965, 710 cm–1. 1H NMR (400.31 MHz, CDCl3): arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
-arabino-
-arabinofuranosyl-(1→5)-
-arabinofuranosyl-(1→5)-2,3-di-O-
-arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
D-arabino-
D
D
D
D
-
D
D
D
D-
D
D
D
D
D
D
D
D-
˜
D
δ = 2.44 (s, 1 H), 3.89–4.07 (m, 13 H), 4.10–4.27 (m, 12 H), 4.32 (dd,
J = 13.2, 4.9 Hz, 1 H), 4.51 (m, 2 H), 4.56–4.70 (m, 10 H), 5.24 (dd,
J = 10.4, 1.4 Hz, 1 H), 5.32 (s, 1 H), 5.39 (dd, J = 17.1, 1.7 Hz, 1 H),
5.43–5.47 (m, 12 H), 5.61 (d, J = 1.2 Hz, 1 H), 5.66–5.73 (m, 22 H),
furanosyl-(1→5)-2,3-di-O-benzoyl-α-
2,3-di-O-benzoyl-α-
benzoyl-α-
D
D
D
D-
D
Eur. J. Org. Chem. 2017, 4794–4802
www.eurjoc.org
4800
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Full Paper
furanosyl-(1→5)-2,3-di-O-benzoyl-α-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α-
-arabinofuranoside (19): M.p. 155.8 °C. [α]D25 = +25.2
D
-arabinofuranosyl-(1→5)-
165.6 (12 C), 165.7 (5 C), 166.1 ppm. HRMS (MALDI-TOF): calcd. for
[C345H294O109Na]+ 6206.7494; found 6206.1763.
D
D
Allyl α-
D
-Arabinofuranosyl-(1→5)-α-
D
-arabinofuranosyl-(1→5)-
(c = 1.0 in CHCl3). IR (CHCl3): ν = 3066, 2926, 1723, 1602, 1453, 1265,
˜
α- -arabinofuranosyl-(1→5)-α-
D
D
-arabinofuranosyl-(1→5)-α-
D
D
D
D
D
D
D
D
-
-
-
-
-
-
-
-
1176, 1108, 1070, 1028, 966, 710 cm–1. 1H NMR (400.31 MHz, CDCl3):
δ = 1.09 (s, 9 H), 3.96–4.01 (m, 18 H), 4.02–4.06 (m, 2 H), 4.16 (dd,
J = 13.2, 6.0 Hz, 1 H), 4.20–4.29 (m, 18 H), 4.35 (dd, J = 13.2, 4.7 Hz,
1 H), 4.51–4.60 (m, 2 H), 4.65–4.75 (m, 17 H), 5.28 (d, J = 10.4 Hz, 1
H), 5.35 (s, 1 H), 5.41–5.48 (m, 19 H), 5.64 (m, 2 H), 5.70–5.72 (m, 36
H), 6.01 (dddd, J = 16.5, 10.7, 5.8, 5.2 Hz, 1 H), 7.24–7.35 (m, 36 H),
7.36–7.51 (m, 66 H), 7.54–7.61 (m, 18 H), 7.77 (m, 4 H), 7.92–7.99
(m, 36 H), 8.04–8.13 (m, 40 H) ppm. 13C NMR (100.67 MHz, CDCl3):
δ = 19.3, 26.8, 26.8, 26.8, 63.4, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8,
65.8, 65.8, 65.8, 65.8, 65.9, 65.9, 65.9, 65.9, 65.9, 65.9, 66.0, 67.8, 77.2,
77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2,
77.2, 77.3, 77.3, 77.4, 77.4, 81.5, 81.5, 81.5, 81.5, 81.5, 81.5, 81.5, 81.5,
81.5, 81.5, 81.5, 81.5, 81.5, 81.5, 81.6, 81.6, 81.6, 81.6, 81.9, 81.9, 82.1,
82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1,
82.1, 82.1, 82.1, 83.2, 104.8, 105.8, 105.9, 105.9, 105.9, 105.9, 105.9,
105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9,
106.0, 106.0, 117.4, 127.7 (6 C), 128.3 (34 C), 128.4 (4 C), 128.5 (38
C), 129.1 (35 C), 129.3 (3 C), 129.7 (2 C), 129.8 (70 C), 129.9 (2 C),
130.0 (2 C), 133.0, 133.1 (16 C), 133.2 (2 C), 133.3 (4 C), 133.4 (17
C), 133.8, 135.7, 135.7, 135.7, 135.7, 165.1 (16 C), 165.2, 165.2, 165.4,
165.5, 165.6 (17 C), 165.7 ppm. HRMS (MALDI-TOF): calcd. for
[C380H328O115SiNa]+ 6784.9619; found 6784.8623.
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
arabinofuranosyl-(1→5)-α-
D
D
D
D
D
D
D
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
-arabinofuranosyl-(1→5)-α-
arabinofuranoside (21): M.p. 254.3 °C. [α]D25 = +113.2 (c =
1.0 in H2O). IR (CHCl3): ν = 3355, 1696, 1642, 1425, 1368, 1237,
˜
1095 cm–1. 1H NMR (600.40 MHz, D2O, internal standard CH3COCH3):
δ = 2.22 (CH3COCH3), 3.71 (dd, J = 12.3, 5.8 Hz, 1 H), 3.78–3.82 (m,
18 H), 3.84–3.90 (m, 19 H), 3.95 (dd, J = 6.0, 3.3 Hz, 1 H), 4.00–4.01
(m, 18 H), 4.08–4.10 (m, 3 H), 4.11–4.13 (m, 18 H), 4.18–4.23 (m, 18
H), 4.23–4.27 (m, 1 H), 5.07–5.09 (m, 19 H), 5.28 (dt, J = 10.5, 1.4 Hz,
1 H), 5.36 (dt, J = 17.3, 1.5 Hz, 1 H), 5.97 (dddd, J = 16.5, 10.8, 5.7,
5.3 Hz, 1 H) ppm. 13C NMR (100.67 MHz, D2O, internal standard
CH3COCH3): δ = 30.8 (CH3), 61.7, 67.3, 67.4, 67.4, 67.4, 67.4, 67.4,
67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 67.4, 69.4,
77.0, 77.0, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 77.3,
77.3, 77.3, 77.3, 77.3, 77.3, 77.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3,
81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.3, 81.4, 81.4, 82.6,
82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9, 82.9,
82.9, 82.9, 82.9, 82.9, 84.5, 107.1, 107.9, 108.0, 108.0, 108.0, 108.0,
108.0, 108.0, 108.0, 108.0, 108.0, 108.0, 108.0, 108.0, 108.0, 108.0,
108.0, 108.0, 108.0, 119.1, 133.9, 215.9 (CO) ppm. HRMS (MALDI-
TOF): calcd. for [C98H158O77Na]+ 2590.8379; found 2590.1692.
Allyl 2,3-Di-O-benzoyl-α-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofur-
anosyl-(1→5)-2,3-di-O-benzoyl-α-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α- -arabino-
furanosyl-(1→5)-2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-
2,3-di-O-benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-
benzoyl-α- -arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-D-
D
-arabinofuranosyl-(1→5)-2,3-di-O-
D
D-
D
D
D
Acknowledgments
B. M. acknowledges a research fellowship from the Council of
D
D-
D
D
-arabinofuranosyl-(1→5)- Scientific and Industrial Research (CSIR) – UGC-NET. R. R. A. P.
D
thanks the IISER Pune for a fellowship. The authors thank Nitin
Dalvi and the Department of Science and Technology (DST) –
FIST for funding the high-field NMR facilities at IISER Pune. S. M.
and S. H. thank the Department of Science and Technology
(DST) – SERB, New Delhi (SB-OC/CB-03/2014) for financial sup-
port.
D
D-
D
D
D
D
arabinofuranosyl-(1→5)-2,3-di-O-benzoyl-α-D-arabinofuran-
oside (20): M.p. 135.3 °C. [α]D25 = +22.4 (c = 1.0 in CHCl3). IR (CHCl3):
ν = 3065, 2931, 2861, 1722, 1602, 1490, 1453, 1176, 1102, 1069,
Keywords: Glycosylation · Oligosaccharides · Gold ·
Homogeneous catalysis · Carbohydrates · Polysaccharides
˜
1027, 965, 709 cm–1. 1H NMR (400.31 MHz, CDCl3): δ = 2.47 (s, 1 H),
3.90–4.95 (m, 20 H), 4.12 (dd, J = 6.5, 1.7 Hz, 1), 4.15 (dd, J = 6.5,
1.7 Hz, 1 H), 4.20–4.28 (m, 16 H), 4.33 (dd, J = 13.2, 4.9 Hz, 1 H),
4.52 (q, J = 4.7 Hz, 2 H), 4.61–4.69 (m, 16 H), 5.25 (dd, J = 10.5,
1.5 Hz, 1 H), 5.33 (s, 1 H), 5.36–5.49 (m, 19 H), 5.62 (d, J = 1.2 Hz, 1
H), 5.67–5.72 (m, 33 H), 5.98 (dddd, J = 16.6, 10.5, 5.9, 5.0 Hz, 1 H),
7.24–7.30 (m, 35 H), 7.40–7.48 (m, 55 H), 7.49–7.63 (m, 18 H), 7.90–
7.97 (m, 34 H), 8.05–8.10 (m, 38 H) ppm. 13C NMR (100.67 MHz,
CDCl3): δ = 62.3, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.8,
65.8, 65.8, 65.8, 65.8, 65.8, 65.8, 65.9, 66.1, 67.8, 77.2, 77.2, 77.2, 77.2,
77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.2, 77.3, 77.3, 77.3, 77.7, 81.6,
81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6, 81.6,
81.6, 81.6, 81.6, 81.6, 81.7, 82.0, 82.0, 82.0, 82.1, 82.1, 82.1, 82.1, 82.1,
82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 82.1, 83.7, 104.8,
105.8, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9,
105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 105.9, 117.4, 128.3 (36 C),
128.5 (36 C), 129.0, 129.0, 129.0, 129.0, 129.1 (28 C), 129.2, 129.2,
129.3, 129.3, 129.8 (32 C), 129.9 (40 C), 133.2 (16 C), 133.3, 133.4
(12 C), 133.5 (6 C), 133.6, 133.8, 165.1 (12 C), 165.2 (5 C), 165.4,
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Received: May 22, 2017
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