TMSOTf mediated stereoselective synthesis of α-C-glycosides from unactivated aryl acetylenes

Article abstract of DOI:10.1007/s10719-016-9718-7

A metal free and highly stereoselective procedure for the synthesis of 2,3-unsaturated-C-glycosides has been developed between glycals and unactivated aryl acetylenes in the presence of TMSOTf through a triflated C-vinyl glycosides intermediate. The flexi

Full text of DOI:10.1007/s10719-016-9718-7

Glycoconj J
DOI 10.1007/s10719-016-9718-7
ORIGINAL ARTICLE
TMSOTf mediated stereoselective synthesis of α-C-glycosides
from unactivated aryl acetylenes
Heshan Chen1 & Xiaosheng Luo1 & Saifeng Qiu1 & Wengjie Sun 1 & Jianbo Zhang1
Received: 13 May 2016 /Revised: 7 July 2016 /Accepted: 18 July 2016
#
Springer Science+Business Media New York 2016
Abstract A metal free and highly stereoselective procedure
for the synthesis of 2,3-unsaturated-C-glycosides has been
developed between glycals and unactivated aryl acetylenes
in the presence of TMSOTf through a triflated C-vinyl glyco-
sides intermediate. The flexibility of the procedure was tested
by a wide variety of glycals and unactivated aryl acetylenes
(20 examples). The corresponding alkynyl C-glycosides were
obtained in good yields with completely α-selectivity in a
short time (<25 min). And a plausible mechanism for the
synthesis of alkynyl C-glycosides was depicted.
transformed into other chiral carbon analogues of synthetic
carbohydrates or used to build up building blocks of natu-
ral products (i.e. ciguatoxin, gambiertoxin, tautomycin)
[7–11]. The previous methods for the synthesis of C-
alkynyl glycosides are using the activated alkynes, such
as silylacetylenes [12–14], iodoacetylenes, [15]
alkynyltrifluoroborates, [16] reacted with the glycals
through a Ferrier-type rearrangement, which involves two
steps namely activation of alkynes and then Ferrier-type
alkynylation of gycals using activated alkynes. These
methods often suffer the drawbacks such as intricacy oper-
ation and low overall yield. Recently, Yousuf’s group have
reported the direct access to alkynyl C-glycosides under
coppertriflate/ascorbic acide catalysis [17] or zinc/
bromoethylacetate catalysis [18]. Another method for di-
rected C-alkynylation of glycals was reported by Shah,
et.al., [19], which used TMSOTf as a promoter to gener-
ate in situ trimethylsilylacetylene for C-alkynylation at
low -20 °C in dichloromethane. In the present paper we
describe the in situ generation of triflated C-vinyl glyco-
sides catalyzed by TMSOTf between glycals and
unactivated aryl acetylenes and its subsequent usage for
highly stereoselective synthesis of alkynyl C-glycosides in
dichloroethane at 80 °C. As far as we know, this is the
first report which describes the in situ generation of
triflated C-vinyl glycosides and its further application to
synthesis of C-glycosides.
.
.
.
Keywords Metal free C-glycosides TMSOTf Aryl
.
acetylenes Glycals
Stereoselective synthesis of C-glycosides has become very
significant in the fields of carbohydrate and biological chem-
istry, since C-glycosides widely exist in the biologically active
natural products [1–3]. C-glycosides are versatile chiral build-
ing blocks for the synthesis of optically active compounds and
many biologically natural products, since it allows for the
introduction of carbon chains into sugar chirons [4–6].
Moreover, specifically C-alkynyl glycosides are attractive
due to the presence of a triple bond that can be easily
Electronic supplementary material The online version of this article
(doi:10.1007/s10719-016-9718-7) contains supplementary material,
which is available to authorized users.
In the last years we have developed efficient methods to
synthesize 2,3-unsaturated-O-glycosides, S-glycosides, aryl-
C-glycosides and 2-deoxy-O-aryl-glycosides using solid acid
or Lewis acid as catalysts [20–25], which are often used to
synthesize bioactive glycoconjugates. Since C-glycosides are
stable analogs of O-glycosides and less prone to hydrolysis by
acids and glycosidases, we have now developed a metal free
* Jianbo Zhang
jbzhang@chem.ecnu.edu.cn
1
School of Chemistry and Molecular Engineering, East China Normal
University, Shanghai 200241, China

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and highly stereoselective method to synthesize C-glycosides
from unactivated aryl acetylenes.
As we have successfully used TMSOTf to synthesize 2-
deoxy-O-aryl-glycosides before [24], we then tried to use it to
promote the reaction at room temperature. At the beginning,
the 1b was got as the major product and little amount 1a was
observed in TLC; and some of 1b transformed to 1a after
extending the reation time. Finally, 24 % yield 1a and
20 % yield 1b were obtained after 4 h (Table 1, entry
4). Increasing the amount of TMSOTf from 0.3 eq to
0.6 eq, 1a could be obtained in 30 % yield. Further
increasing the catalyst amount (up to 1.2 eq) would
At the outset, tri-O-acetyl-D-glucal 1 and phenylacetylene
2 were chosen as starting materials and dichloroethane as sol-
vent. The reaction between 1 and 2 was first investigated with
two kinds of solid acids as catalyst, but the reaction did not
lead to the desired compound (Table 1, entries 1, 2). We then
used BF3·OEt2 to promote the reaction, it afforded a mixture,
and after tedious separation, 1a was isolated in a low 18 %
yield (Table 1, entry 3).
Table 1 Optimization of reaction conditions for C-alkynylation of glycalsa
a In all case 0.1 mmol of 1, 1.2 Eq. 2, 30 mg 4 Å molecular sieves (powder), 1.5 mL solvent
b Isolated yield, In all case α:β > 19:1, determined by 1 H NMR
c ND = not determined. d Without 4 Å molecular sieves

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not improve the yields of both 1a and 1b (Table 1,
entries 5–7). Interestingly, rising the reaction tempera-
ture from 20 °C to 80 °C largely favors the transforma-
tion from 1b to 1a and 80 °C was found to be the best
temperature (Table 1, entries 7–10). Further optimization
revealed that using 0.6 equivalent TMSOTf (at 80 °C)
to promote the reaction could afforded the 1a in highest
yield (67 %) in a short time (Table 1, entry 10). With
respect to other solvents, no improvement in the yield
was observed. Using toluene as solvent, C-glycoside
was obtained only in 51 % yield. When using THF as
solvent, no product could be obtained (Table 1, entries
11–13). Without adding 4 Å molecular sieves to the
reaction, the yield of 1a was slight decreased (Table 1,
entries 14), while the start materials keep intact if only
used 4 Å molecular sieves as catalyst. Under these op-
timization conditions, 1a was formed as a single α-
isomer without any anomerization. The structure of 1a
was determined through spectroscopic analysis and the
spectrum data is well agreement with the reported data
[12, 15].
With the optimal condition developed, we next investigat-
ed the reaction scope using a variety of acceptors. As show in
Table 2, glycosidation of tri-O-acetyl-D-glucal with various
phenylacetylenes bearing electron-donating or electron-
withdrawing groups proceeded smoothly under the specified
conditions (1a-4a). The reaction afforded the corresponding
acetylene glycosides in good yields with completely α-selec-
tivity. Although the reaction between tri-O-acetyl-D-glucal
and 4-methoxyphenylacetylene failed under the optimal con-
ditions, modification of the reaction temperature (at 50 °C)
successfully obtained the desired product 5a in moderate yield
in 3 min. Motivated by these results, other glycals were also
subjected to the same reaction to obtain the corresponding
products. Likewise, when tri-O-acetyl-D-galactal was treated
with various phenylacetylenes under the optimal condition, cor-
responding acetylene galactosides 6a-9a were obtained in good
yields with excellent stereoselectivity. It has been observed that in
general the galactal series reacted faster than glucal series.
Meanwhile, tri-O-benzoyl-D-glucal and tri-O-benzoyl-D-
galactal also undergo the same reaction smoothly under the op-
timal condition to afford the corresponding sugar acetylene 14a-
17a in good yields within a short time.
intact. In all cases the C-glycosides (1a–20a) were obtained
in 50–70 % isolated yields with completely α-selectivity at a
short time (3-25 min). The structures of the products 1a–20a
were determined by 1H and 13C NMR and also by comparison
with the reported data [12, 13, 16, 17].
According to the experimental results and literature prece-
dent, [7, 26, 27] a possible mechanism is outlined in Scheme
1. Firstly, tri-O-acetyl-D-glucal was activated by TMSOTf to
generate oxocarbonium ion intermediate 21a, with concomi-
tant release of [OTf]− anion, then the [OTf]− anion activated
the phenylacetylene and attacked the intermediate 21a from
the α-side, affording the vinyl triflate 1b, which further elim-
inated at 80 °C to afford the alkynyl C-glycoside. The stereo-
chemistry should largely be determined by the coordination
between two π-electron orbitals of the oxocarbonium and
acetylene groups, while the stereoelectronic control allows
the α-pseudo-axial orbital to make the bond [7]. When the
reaction proceeded at 0 °C with other conditions unchanged,
the vinyl triflate 1b was obtained as major product. The struc-
ture of the vinyl triflate 1b was confirmed by 1H NMR spec-
trum and high resolution mass spectrum (see supporting in-
formation). The molecular formula of 1b was determined to
be C19H19F3O8S by HRMS (ESI) and 1H NMR spectroscopy
experiments. The 1H NMR spectra confirmed the presence of
19 protons, including two acetate groups and five aromatic
proton signals. Resonances at 6.01 (d, J = 9.7 Hz, 1H), 5.90
(dd, J = 10.7, 1.7 Hz, 1H), 5.86 (ddd, J = 10.5, 2.6, 1.4 Hz,
1
1H), apart from the aromatic proton signals in the H NMR
spectrum were assigned to the protons of vinyl triflate (H-7)
and the double bond in pyranoid ring (H-2 and H-3). The
coupling constant between the anomeric proton H-1 and H-7
(JH1, H7 = 9.7 Hz) confirms 1b in a α-isomer.
In summary, we have developed an efficient and metal free
method for the direct synthesis alkynyl C-glycosides from
glycals and unactivated aryl acetylenes. Various glycals, in-
cluding acetyl glycals, benzoyl glycals, deoxysugars, disac-
charides, and aryl acetylenes containning alkyl, fluoro,
methoxy groups were successfully used in the reaction. This
method offers several advantages, such as high
stereoselectivity, short reaction time and simplicity in opera-
tion. These features make this method an attractive alternative
to existing methodologies for the preparation of C- glycosides.
Further studies on using the triflated C-vinyl glycosides to
synthesis of other compounds are underway.
In a further set of experiments, we investigated the gener-
ality of the method with respect to the deoxysugars. As
depicted in Table 2, the reaction of deoxysugars with
phenylacetylenes proceeded cleanly in good yields with
completely α-selectivity (10a-13a, 18a). Compared with oth-
er sugars, the reaction time is shorter in deoxysugars series,
which possibly due to their higher reactivity [24]. Importantly,
the procedure is also reliable to disaccharides. The exclusive
α-C-disaccharides 19a, 20a were obtained in 65 % and 70 %
yields, respectively, and the 1,4-glycosidic bonds remained
General experimental methods
All reagents were purchased with purity of AR and used as
such. All the solvents for chromatography were distilled be-
fore use. Silica gel (10–40 μm, Yantai, China) was used for
column chromatography. TLC plates (10–40 μm, Yantai,
1
China) were applied to monitor reactions. H and 13C NMR

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Table 2 Substrate scope of the reaction process under optimized conditions
a The reaction temperature is 50 °C
spectra were recorded on 500 MHz and 125 MHz, respective-
ly, with a Bruker DRX 500 spectrometer in CDCl3. Chemical
shifts are expressed in parts per million (ppm) with TMS as
the internal standard. MS experiments were performed on
LTQ-XL (Thermo Scientific, USA) with an electrospray
(ESI) ion source. Glycals were prepared following the litera-
ture [25].
(19.8uL, 0.18 mmol, 1.2 equiv) in dry dichloroethane (2 mL)
at 80 °C under nitrogen atmosphere was added the TMSOTf
(16.2uL, 0.09 mmol), The reaction mixture was stirred at 80 °C
for 25 min. After complete conversion, as indicated by TLC
analysis, the reaction mixture was diluted with dichlorometh-
ane (8 mL) and quenched with saturated NaHCO3 (8 mL). The
layers were partitioned and the aqueous layer was extracted
with dichloromethane (2 × 8 mL). The combined organic
layers were washed with saturated NaHCO3 (12 mL) and sat-
urated brine (12 mL), then dried over anhydrous Na2SO4.
After evaporation of the solvent under reduced pressure, the
crude product was purified by column chromatography on
silica gel (ethyl acetate - petroleum ether =1:12) affording 1a
(31.6 mg, 67 % yield).
Typical procedure for the synthesis
of C-alkynylglycosides
A mixture of 3, 4, 6-tri-O-acetyl-D-glucal (40.8 mg,
0.15 mmol), 4Å molecular sieves (60 mg) and phenylacetylene

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Scheme 1 Plausible mechanism of TMSOTf mediated reaction of acetylene and glucal
Product characterization data
(dt, J = 10.2, 1.8 Hz, 1H), 5.34 (dd, J = 8.9, 1.9 Hz, 1H), 5.21–
5.17 (m, 1H), 4.26 (d, J = 3.9 Hz, 2H), 4.22–4.17 (m, 1H),
2.62–2.57 (m, 2H), 2.11 (s, 3H), 2.10 (s, 3H), 1.64–1.58 (m,
2H), 1.35–1.29 (m, 4H), 0.88 (t, J = 6.9 Hz, 3H). HRMS
(ESI): m/z Calculated for [M + Na]+ C23H28O5Na 407.1829,
found 407.1844.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-
enopyranosyl)-2-phenylacetylene(1a) H NMR (500 MHz,
1
CDCl3) δ 7.45 (dd, J = 7.4, 1.7 Hz, 2H), 7.36–7.30 (m, 3H),
5.98 (ddd, J = 10.0, 3.3, 1.7 Hz, 1H), 5.83 (d, J = 10.2 Hz,
1H), 5.34 (dd, J = 8.9, 1.8 Hz, 1H), 5.23–5.18 (m, 1H), 4.27
(d, J = 3.7 Hz, 2H), 4.23–4.17 (m, 1H), 2.11 (s, 3H), 2.10 (s,
3H). 13C NMR (125 MHz, CDCl3) δ 171.07, 170.48,
131.97(2C), 129.36, 128.90, 128.47(2C), 125.63, 122.32,
86.82, 84.81, 70.17, 64.95, 64.60, 63.22, 21.17, 20.97.
HRMS (ESI): m/z Calculated for [M + Na]+ C18H18O5Na
337.1046, found 337.1057.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-
1
enopyranosyl)-(2-(4-methoxyphenyl)ethynyl ) (5a) H
NMR (500 MHz, CDCl3) δ 7.43–7.35 (m, 2H), 6.88–6.80
(m, 2H), 5.98 (ddd, J = 10.2, 3.5, 1.9 Hz, 1H), 5.81 (dt,
J = 10.2, 1.8 Hz, 1H), 5.37–5.31 (m, 1H), 5.19 (dt, J = 3.5,
1.8 Hz, 1H), 4.26 (d, J = 3.9 Hz, 2H), 4.22–4.16 (m, 1H), 3.82
(s, 3H), 2.10 (s, 6H). HRMS (ESI): m/z Calculated for [M +
Na]+ C19H20O6Na 367.1152, found 367.1171.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-
1
enopyranosyl)-(m-tolylethynyl) (2a) H NMR (500 MHz,
CDCl3) δ 7.30–7.12 (m, 4H), 5.97 (dd, J = 8.4, 1.5 Hz, 1H),
5.82 (d, J = 10.0 Hz, 1H), 5.39–5.30 (m, 1H), 5.19 (s, 1H),
4.27 (d, J = 3.4 Hz, 2H), 4.23–4.15 (m, 1H), 2.33 (s, 3H), 2.11
(s, 3H), 2.10 (s, 3H). 13C NMR (125 MHz, CDCl3) δ 170.89,
170.30, 138.02, 132.38, 129.62, 129.26, 128.88, 128.21,
125.41, 121.95, 86.84, 84.27, 69.96, 64.79, 64.47, 63.05,
21.16, 21.00, 20.81. HRMS (ESI): m/z Calculated for [M +
Na]+ C19H20O5Na 351.1203, found 351.1216.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-
enopyranosyl)-2-phenylacetylene(6a) H NMR (500 MHz,
1
CDCl3) δ 7.44 (dd, J = 7.6, 1.8 Hz, 2H), 7.37–7.29 (m, 3H),
6.15 (dd, J = 10.0, 3.8 Hz, 1H), 6.06 (ddd, J = 10.0, 5.4,
1.8 Hz, 1H), 5.27 (dd, J = 3.6, 1.9 Hz, 1H), 5.12 (dd,
J = 5.4, 2.3 Hz, 1H), 4.44 (ddd, J = 7.4, 5.3, 2.4 Hz, 1H),
4.32 (dd, J = 11.5, 5.2 Hz, 1H), 4.22 (dd, J = 11.5, 7.3 Hz, 1H),
2.10 (s, 3H), 2.08 (s, 3H). HRMS (ESI): m/z Calculated for
[M + Na]+ C18H18O5Na 337.1046, found 337.1050.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-
1
enopyranosyl)-(2-(4-fluorophenyl)ethynyl ) (3a) H NMR
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-
enopyranosyl)-(m-tolylethynyl) (7a) H NMR (500 MHz,
1
(500 MHz, CDCl3) δ 7.46–7.40 (m, 2H), 7.02 (t, J = 8.6 Hz,
2H), 5.97 (ddd, J = 10.2, 3.4, 1.8 Hz, 1H), 5.83 (dt, J = 10.2,
1.7 Hz, 1H), 5.34 (dd, J = 8.9, 1.9 Hz, 1H), 5.21–5.16 (m, 1H),
4.27 (d, J = 3.9 Hz, 2H), 4.20–4.15 (m, 1H), 2.10 (s, 6H).
HRMS (ESI): m/z Calculated for [M + Na]+ C18H17FO5Na
355.0952, found 355.0971.
CDCl3) δ 7.29–7.18 (m, 4H), 6.15 (dd, J = 9.9, 3.6 Hz, 1H),
6.05 (ddd, J = 9.8, 5.3, 1.6 Hz, 1H), 5.26 (d, J = 1.4 Hz, 1H),
5.12 (dd, J = 5.0, 2.0 Hz, 1H), 4.43 (dd, J = 8.4, 3.4 Hz, 1H),
4.32 (dd, J = 11.5, 5.3 Hz, 1H), 4.22 (dd, J = 11.4, 7.3 Hz, 1H),
2.33 (s, 3H), 2.10 (s, 3H), 2.08 (s, 3H). 13C NMR (125 MHz,
CDCl3) δ 170.69, 170.39, 138.02, 132.35, 132.05, 129.63,
128.84, 128.20, 122.35, 121.86, 87.03, 83.68, 69.64, 64.37,
63.31, 62.80, 21.14, 20.83, 20.78. HRMS (ESI): m/z
Calculated for [M + Na]+ C19H20O5Na 351.1203, found
351.1223.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-
1
enopyranosyl)-(2-(4-pentylphenyl)ethynyl ) (4a) H NMR
(500 MHz, CDCl3) δ 7.36 (d, J = 8.1 Hz, 2H), 7.13 (d,
J = 8.0 Hz, 2H), 5.98 (ddd, J = 10.2, 3.4, 1.9 Hz, 1H), 5.81

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1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-
enopyranosyl)-(2-(4-fluorophenyl)ethynyl ) (8a) H NMR
4.9 Hz, 3H), 5.96 (ddd, J = 10.2, 3.4, 1.8 Hz, 1H), 5.80 (dt,
J = 10.2, 1.9 Hz, 1H), 5.17–5.11 (m, 1H), 5.07 (ddd, J = 8.2,
3.9, 1.9 Hz, 1H), 4.08 (dq, J = 12.6, 6.3 Hz, 1H), 2.10 (s, 3H),
1.29 (d, J = 6.3 Hz, 3H). HRMS (ESI): m/z Calculated for
[M + Na]+ C16H16O3Na 279.0992, found 279.0997.
1
(500 MHz, CDCl3) δ 7.42 (dd, J = 8.5, 5.4 Hz, 2H), 7.01 (t,
J = 8.6 Hz, 2H), 6.13 (dd, J = 9.9, 3.6 Hz, 1H), 6.09–6.02 (m,
1H), 5.25 (d, J = 1.3 Hz, 1H), 5.11 (dd, J = 4.9, 2.0 Hz, 1H),
4.42 (t, J = 5.9 Hz, 1H), 4.31 (dd, J = 11.5, 5.3 Hz, 1H), 4.22
(dd, J = 11.4, 7.3 Hz, 1H), 2.08 (d, J = 13.4 Hz, 6H). 13C NMR
(125 MHz, CDCl3) δ 170.66, 170.36, 162.71 (d,
JcF = 247.5 Hz), 133.77, 133.70, 131.82, 122.49, 118.12 (d,
JcF = 3.5 Hz), 115.71, 115.53, 85.75, 83.74, 69.65, 64.27,
63.21, 62.74, 20.80, 20.75. HRMS (ESI): m/z Calculated for
[M + Na]+ C18H17FO5Na 355.0952, found 355.0966.
1-(4-O-acetyl-2,3,6-trideoxy-α-L-erythro-hex-2-
enopyranosyl)-(2-(4-fluorophenyl)ethynyl ) (13a) 1H NMR
(500 MHz, CDCl3) δ 7.44 (dd, J = 8.5, 5.5 Hz, 2H), 7.04–6.97
(m, 2H), 5.94 (ddd, J = 10.1, 2.7, 1.7 Hz, 1H), 5.80 (d,
J = 10.2 Hz, 1H), 5.12 (d, J = 1.3 Hz, 1H), 5.07 (dd,
J = 8.1, 1.7 Hz, 1H), 4.09–4.02 (m, 1H), 2.10 (s, 3H), 1.29
(d, J = 6.3 Hz, 3H). 13C NMR (125 MHz, CDCl3) δ 170.51 s),
162.65(d, JcF = 247 Hz), 133.78 (2C), 129.17, 125.71,
118.43, 115.65, 115.47, 85.25, 84.91, 70.24, 68.22, 63.74,
21.10, 18.05. HRMS (ESI): m/z Calculated for [M + Na]+
C16H15FO3Na 298.0897, found 298.0899.
1-(4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-
1
enopyranosyl)-(2-(4-pentylphenyl)ethynyl ) (9a) H NMR
(500 MHz, CDCl3) δ 7.35 (d, J = 8.2 Hz, 2H), 7.13 (d,
J = 8.2 Hz, 2H), 6.14 (dd, J = 10.1, 3.8 Hz, 1H), 6.05 (ddd,
J = 10.0, 5.4, 1.9 Hz, 1H), 5.26 (dd, J = 3.7, 1.9 Hz, 1H), 5.11
(dd, J = 5.4, 2.4 Hz, 1H), 4.44 (ddd, J = 7.5, 5.3, 2.4 Hz, 1H),
4.31 (dd, J = 11.5, 5.3 Hz, 1H), 4.21 (dd, J = 11.5, 7.3 Hz, 1H),
2.63–2.55 (m, 2H), 2.08 (d, J = 11.7 Hz, 6H), 1.60 (dd,
J = 14.2, 6.7 Hz, 2H), 1.31 (tdd, J = 12.9, 9.5, 3.5 Hz, 4H),
0.88 (t, J = 7.0 Hz, 3H). 13C NMR (125 MHz, CDCl3) δ
170.74, 170.43, 144.03, 132.17, 131.73 (2C), 128.44 (2C),
122.31, 119.19, 87.10, 83.36, 69.64, 64.45, 63.38, 62.86,
35.83, 31.38, 30.87, 22.48, 20.87, 20.82, 13.98. HRMS
(ESI): m/z Calculated for [M + Na]+ C23H28O5Na 407.1829,
found 407.1839.
1-(4,6-di-O-benzoyl-2,3-dideoxy-α-D-erythro-hex-2-
enopyranosyl)-2-phenylacetylene(14a) 1H NMR (500 MHz,
CDCl3) δ 8.11–8.00 (m, 4H), 7.60–7.28 (m, 11H), 6.06 (ddd,
J = 10.2, 3.4, 1.8 Hz, 1H), 5.99 (dt, J = 10.2, 1.7 Hz, 1H), 5.71
(dd, J = 8.7, 1.8 Hz, 1H), 5.27 (dt, J = 3.5, 1.9 Hz, 1H), 4.65
(dd, J = 11.1, 1.8 Hz, 1H), 4.56–4.46 (m, 2H). HRMS (ESI):
m/z Calculated for [M + Na]+ C28H22O5Na 461.1359, found
461.1376.
1-(4,6-di-O-benzoyl-2,3-dideoxy-α-D-erythro-hex-2-
1
enopyranosyl)-(m-tolylethynyl) (15a) H NMR (500 MHz,
1-(4-O-acetyl-2,3-dideoxy-α-D-erythro-penta-2-
enopyranosyl)-2-phenylacetylene(10a) 1H NMR (500 MHz,
CDCl3) δ 7.44 (dd, J = 7.5, 1.8 Hz, 2H), 7.32 (t, J = 6.2 Hz,
3H), 6.14 (dd, J = 10.1, 3.6 Hz, 1H), 6.00 (dd, J = 10.0,
4.8 Hz, 1H), 5.20–5.14 (m, 1H), 5.10–5.03 (m, 1H), 4.27
(dd, J = 13.0, 3.0 Hz, 1H), 3.93 (d, J = 13.0 Hz, 1H), 2.11
(s, 3H). HRMS (ESI): m/z Calculated for [M + CH3OH +
Na]+ C16H18O4Na 297.1103, found 297.0629.
CDCl3) δ 8.05 (dd, J = 11.1, 4.1 Hz, 4H), 7.60–7.49 (m, 2H),
7.43 (t, J = 7.8 Hz, 2H), 7.36 (t, J = 7.8 Hz, 2H), 7.26–7.12 (m,
4H), 6.05 (ddd, J = 10.2, 3.4, 1.8 Hz, 1H), 5.98 (dt, J = 10.2,
1.7 Hz, 1H), 5.70 (dd, J = 8.7, 1.8 Hz, 1H), 5.26 (dt, J = 3.5,
1.8 Hz, 1H), 4.65 (dd, J = 10.9, 1.7 Hz, 1H), 4.51 (ddd,
J = 17.2, 8.7, 4.1 Hz, 2H), 2.32 (s, 3H). 13C NMR
(125 MHz, CDCl3) δ 166.34, 165.87, 138.00, 133.34,
132.96, 132.35, 129.85, 129.79 (2C), 129.74 (2C), 129.58,
129.54, 129.40, 128.86, 128.42 (2C), 128.26 (2C), 128.19,
125.78, 121.99, 86.75, 84.48, 70.35, 65.83, 64.63, 63.87,
21.17. HRMS (ESI): m/z Calculated for [M + Na]+
C29H24O5Na 475.1516, found 475.1527.
1-(4-O-acetyl-2,3-dideoxy-α-D-erythro-penta-2-
enopyranosyl)-(2-(4-fluorophenyl)ethynyl ) (11a) 1H NMR
(500 MHz, CDCl3) δ 7.42 (dd, J = 8.6, 5.4 Hz, 2H), 7.00 (t,
J = 8.6 Hz, 2H), 6.12 (dd, J = 9.9, 3.1 Hz, 1H), 6.00 (dd,
J = 9.3, 4.3 Hz, 1H), 5.15 (s, 1H), 5.07 (s, 1H), 4.25 (dd,
J = 12.9, 2.8 Hz, 1H), 3.93 (d, J = 12.9 Hz, 1H), 2.11 (s,
3H). 13C NMR (125 MHz, CDCl3) δ 170.68, 162.67 (d,
JcF = 249 Hz), 133.79, 133.71, 131.91, 122.60, 118.18,
115.68, 115.50, 85.44, 84.22, 64.25, 63.83, 63.36, 21.07.
HRMS (ESI): m/z Calculated for [M + Na]+ C15H13FO3Na
283.0741, found 283.0729.
1-(4,6-di-O-benzoyl-2,3-dideoxy-α-D-threo-hex-2-
enopyranosyl)-2-phenylacetylene(16a) 1H NMR (500 MHz,
CDCl3) δ 8.08–8.02 (m, 4H), 7.62–7.27 (m, 11H), 6.22 (p,
J = 10.2 Hz, 2H), 5.45 (d, J = 1.9 Hz, 1H), 5.34 (d, J = 1.6 Hz,
1H), 4.76–4.62 (m, 2H), 4.55 (dd, J = 11.1, 4.7 Hz, 1H).
HRMS (ESI): m/z Calculated for [M + Na]+ C28H22O5Na
461.1359, found 461.1375.
1-(4-O-acetyl-2,3,6-trideoxy-α-L-erythro-hex-2-
enopyranosyl)-2-phenylacetylene (12a) 1H NMR
(500 MHz, CDCl3) δ 7.52–7.41 (m, 2H), 7.32 (dd, J = 6.0,
1-(4,6-di-O-benzoyl-2,3-dideoxy-α-D-threo-hex-2-
enopyranosyl)-(m-tolylethynyl) (17a) H NMR (500 MHz,
CDCl3) δ 8.05 (m, 4H), 7.55 (dt, J = 21.1, 7.3 Hz, 2H), 7.41
1

Glycoconj J
(m, 4H), 7.25–7.11 (m, 4H), 6.27–6.16 (m, 2H), 5.45 (s, 1H),
5.33 (s, 1H), 4.75–4.62 (m, 2H), 4.56 (dd, J = 11.2, 4.6 Hz,
1H), 2.30 (s, 3H). 13C NMR (125 MHz, CDCl3) δ 166.21,
165.97, 137.97, 133.26, 133.00, 132.32, 132.31, 129.81,
129.77 (2C), 129.70 (2C), 129.62, 129.56, 128.80, 128.43
(2C), 128.29 (2C), 128.17, 122.59, 121.89, 86.95, 83.91,
70.24, 64.5, 64.11, 63.52, 21.14. HRMS (ESI): m/z
Calculated for [M + Na]+ C29H24O5Na 475.1516, found
475.1515.
(dd, J = 9.6, 1.5 Hz, 1H), 4.23 (dd, J = 12.1, 6.3 Hz, 1H), 4.17
(dd, J = 12.0, 2.9 Hz, 1H), 3.99 (ddd, J = 9.1, 5.2, 1.5 Hz, 1H),
2.12 (s, 3H), 2.07 (s, 3H). Calculated for [M + Na]+
C19H19F3O8SNa 487.0645, found 487.0633.
Acknowledgments This project was financially supported by Natural
Science Foundation of Shanghai (11ZR1410400), BDAXIA^ Foundation
of East China Normal University (No. 2011DX-288) National Students
Innovative Experimental Projects (No. 1310269021) and large instru-
ments Open Foundation of East China Normal University (2014-
03&20151043).
1-(4-O-benzoyl-2,3-dideoxy-α-D-erythro-penta-2-
enopyranosyl)-2-phenylacetylene(18a) 1H NMR (500 MHz,
CDCl3) δ 8.12–8.05 (m, 2H), 7.59–7.55 (m, 1H), 7.46 (dt,
J = 12.6, 4.6 Hz, 4H), 7.37–7.30 (m, 3H), 6.19 (ddd,
J = 10.1, 3.6, 0.7 Hz, 1H), 6.12 (dddd, J = 10.1, 4.7, 1.8,
1.1 Hz, 1H), 5.35–5.31 (m, 1H), 5.22 (dd, J = 3.1, 2.3 Hz,
1H), 4.39 (dd, J = 13.0, 3.2 Hz, 1H), 4.07 (ddd, J = 12.9, 1.9,
1.1 Hz, 1H). 13C NMR (125 MHz, CDCl3): δ 166.20, 133.13,
132.21, 131.83 (2C), 129.94, 129.78 (2C), 128.69, 128.36
(2C), 128.30 (2C), 122.71, 122.18, 86.52, 84.63, 64.45,
64.42, 63.52. HRMS (ESI): m/z Calculated for [M + Na]+
C20H16O3Na 327.0992, found 327.0989.
Compliance with ethical standards
Conflicts of interest The authors declare that they have no conflicts of
interest.
Ethical approval This article does not contain any studies with human
participants or animals performed by any of the authors.
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1
The vinyl triflates 1b H NMR (500 MHz, CDCl3) δ 7.54
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