Ruthenium catalyzed synthesis of 2,3-unsaturated C-glycosides from glycals

Article abstract of DOI:10.1016/j.carres.2015.01.009

A highly efficient and convenient C-glycosylation method was developed using ruthenium(III) chloride for the synthesis of 2,3-unsaturated C-glycosides. Various nucleophiles such as allyl trimethylsilane, triethylsilane, trimethylsilyl cyanide, trimethylsi

Full text of DOI:10.1016/j.carres.2015.01.009

Carbohydrate Research 406 (2015) 86e92
Contents lists available at ScienceDirect
Carbohydrate Research
journal homepage: www.elsevier.com/locate/carres
Ruthenium catalyzed synthesis of 2,3-unsaturated C-glycosides
from glycals
Batthula Srinivas, Thurpu Raghavender Reddy, Sudhir Kashyap*
D-207, Discovery Laboratory, Organic and Biomolecular Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad 500 007, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A highly efficient and convenient C-glycosylation method was developed using ruthenium(III) chloride
for the synthesis of 2,3-unsaturated C-glycosides. Various nucleophiles such as allyl trimethylsilane,
triethylsilane, trimethylsilyl cyanide, trimethylsilyl azide and heterocycles such as thiophene and furan
reacted smoothly with glycals in the presence of catalytic amount of ruthenium trichloride under mild
reaction conditions.
Received 24 November 2014
Received in revised form
12 January 2015
Accepted 20 January 2015
Available online 29 January 2015
© 2015 Elsevier Ltd. All rights reserved.
Keywords:
Glycal
Ferrier glycosylation
C-glycosides
Stereoselective synthesis
Ruthenium trichloride
1. Introduction
C-glycosides.8 Another reported procedure for the synthesis of 2,3-
unsaturated C-glycosides involves a two step process, Tebbe meth-
The C-glycosides are subject of considerable interest due to the
role played by them as versatile chiral synthons and key in-
termediates for the synthesis of several carbohydrate compounds
of biological significance.1 Significantly, the C-glycosides are uti-
lized as valuable intermediates in the synthesis of several natural
products such as palytoxin, spongistatin, halichondrin,2 and various
ylenation and thermal Claisen rearrangement9a On the other hand,
the scope of Pd-mediated glycosylation9b,c has been demonstrated
in the stereoselective and regioselective construction of glycosidic
linkage via a Pd p-allyl intermediate. However, a combination of Pd-
catalyst and phosphine ligand with a sub-stoichiometric amount of
diethyl zinc as an additive at high temperature is required for the
success of these reactions. In a recent report,9d Mukherjee and co-
worker developed a highly efficient and reliable catalytic system
for the C-glycosylation of glycals with unactivated alkynes using
functionalized b
-C-saccharides.3 Furthermore, they are employed
as powerful synthetic tools for the synthesis of modified carbohy-
drates and analogs of naturally occurring C-nucleosides antibiotics4
and C-linked
a
(2,3)sialylgalactose lactone.5 Besides, the C-glyco-
a combination of Cu(OTf)2 and ascorbic acid. Similarly, the
sides are more stable to hydrolytic cleavage hence utilized as
glycosidase inhibitors and served as potential therapeutic agents
for understanding the mechanism of carbohydrate-processing en-
zymes and other critical cellular processes.6 Particularly, 2,3-
unsaturated C-glycosides are attractive due to the presence of
2,3-olefinic moiety in pyran rings, which could be further func-
tionalized into other carbohydrates derivatives and useful chiral
molecules by using various complexity generating reactions.7
As evident, several reagent systems have been evolved to effect
the Ferrier glycosylation of glycals to obtain 2,3-unsaturated
Ferrier-type C-alkynylations with silylacetylene9e and alkynyltri-
fluoroborates9f compoundshavebeenreported using stoichiometric
amount of BF3$OEt2. However, the indium-mediated C-alkynylation
with iodoalkynes using Barbier reaction required refluxing condi-
tions and excess loading of indium metal and iodoalkyne.9g
Over the decade, the palladium-catalyzed Heck reaction has
been employed for the syntheses of aryl-C-glycosides10 by cross
coupling of glycals with aryl halides,10b,c aryl boronic acids,10d,e and
benzoic acids.10f More recently, Liu and co-worker demonstrated
the synthesis of aryl-C-glycosides by a Pd-catalyzed oxidative Heck
cross-coupling of inactivated glycals and aryl hydrazines.10g How-
ever the Heck type C-glycosylation represent a significant approach
of aryl-C-glycosylation, with restricted substrate scope, use for
expensive and relatively toxic reagents, wherein less stable and
* Corresponding author. Tel.: þ91 402 716 1649; fax: þ91 402 716 0387.
E-mail address: skashyap@iict.res.in (S. Kashyap).
http://dx.doi.org/10.1016/j.carres.2015.01.009
0008-6215/© 2015 Elsevier Ltd. All rights reserved.

B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
87
moisture sensitive organometallic compounds, use of additives
such as strong bases and phosphine ligands,10b harsh conditions
and tedious work-up remains unsolved issues. Therefore, the
development of an efficient and general protocol utilizing nontoxic
and environmental friendly reagent system is desirable for the
synthesis of C-glycosides and carbohydrate intermediates en route
to several biologically important sugar molecules.
The structure and stereochemistry of compound 3a was estab-
lished through spectroscopic analysis and correlated with that of
literature data.12a The 1H NMR spectrum of 3a revealed the absence
of characteristic resonance due to anomeric proton of glucal 1a at
d
6.47 (d, J1-2¼6.2 Hz, 1H), whilst anomeric proton of C-glycoside 3a
was observed at
4.29 (ddd, J¼7.7, 5.7, 1.9 Hz, 1H). Furthermore, the
13C spectrum of C-glycoside 3a unambiguously proved the presence
of olefinic carbons at 133.8, 132.6, 123.5 and 117.4 ppm, whilst all
d
d
other resonances were in complete agreement with the assigned
structure. In addition, compound 3a gave satisfactory MS/HRMS
analysis [HRMS (ESI) m/z [MþNa]þ calcd for C13H18O5Naþ:
277.10464; found: 277.10428].
2. Results and discussion
Recently, we have demonstrated the expeditious synthesis of
a-
D-mannopyranosides and 2,3-unsaturated O-glycosides from glycal
employing ruthenium catalysis.11b,d In continuation of our research
interest towards developing efficient glycosylation methods,11 we
envisioned that the use of ruthenium(III) chloride as eco-friendly
and economical catalyst would be advantage in the carbohydrate
chemistry particularly in the C-glycosides syntheses. Herein, we
report a novel, convenient and efficient method for the C-glyco-
sylation using ruthenium(III) chloride as a versatile and efficient
catalyst under mild reaction conditions.
Next, we investigated the generality of the current protocol for
various silylated C-nucleophiles under optimized condition.
Accordingly, the C-glycosylation reactions of glycal 1a with trime-
thylsilyl cyanide (2b) and triethylsilane (2c) furnished glycosyl cy-
anide 3b and 2,3-unsaturated glycoside 3c, respectively in excellent
yields (Table 2, entry 1,2). Interestingly, the reaction of trime-
thylsilyl azide (2d) as the acceptor with glycal 1a afforded a mixture
of the C-3 azido glycal (3d) with epimeric ratio of 72:28 and the C-1
glycosyl azide (3d0) with an
a/b ratio of 89:11 (Table 2, entry 3). The
To begin with, the C-glycosylation reactions were optimized
using 3,4,6-tri-O-acetyl glucal (1a) as the glycal donor and allyl tri-
methylsilane (2a) as the model acceptor in different organic sol-
vents, results are summarized in Table 1. In initial experiments, the
C-glycosylation coupling reaction of compound 1a with 2a was
carried out in the presence of 5 mol % of RuCl3 in dichloromethane at
room temperature. Whilst moderate conversion was observed in
8 h, the rate of conversion improved to 80% at 40 ꢀC and the corre-
sponding 4,6-di-O-acetyl-2,3-unsaturated C-allylglucoside (3a) was
obtained in 65% yield with an a/b ratio of 90:10 (Table 1, entry 2).
However, no improvement was realized when 1,2-dichloroethane
was used as solvent (Table 1, entries 3,4).
Remarkably, when acetonitrile was employed as the solvent, the
reaction proceeded smoothly at room temperature and furnished
3a in excellent yield (96%) and high selectivity (a:b, 96:4) within
anomeric and epimeric ratios were measured by 1H NMR spec-
troscopy by relative integration of anomeric or separable protons.
These results were consistent and with conformity with that of
observed by other research groups.12a,b The silyl enol ether 2e
worked equally well to obtain the corresponding C-glycosides 3e in
95% yield as stereoisomeric mixture due to prochirality at
a-carbon
(entry 4). Similarly, the C-glycosylation of -keto ester 2f proceeded
b
efficiently to afford the corresponding 2,3-unsaturated C-glycoside
3f in high yield as a stereoisomeric mixture. It is pertinent to
mention that the C-glycosides such as allyl glycosides, glycosyl
azide and glycosyl cyanides offers further synthetic usefulness in
the construction of carbon chains into sugar core and the prepa-
ration of glycopeptides and glycoconjugates bearing chiral sugar-
scaffolds.13
Encouraged by these results, we next focused on coupling of
heterocycles using present protocol to obtain sugar-heterocycles
hybrid C-glycosides, since these compounds have significant syn-
thetic utility for the preparation of biologically active molecules
with potent antiviral and anticancer activities.14 Accordingly, the
Ferrier C-glycosylation of 1a with thiophene (2g) in the presence of
5 mol % RuCl3 in acetonitrile at ambient temperature resulted the
30 min (Table 1, entry 5). On the other hand, solvents such as
toluene, THF, diethyl ether could not afford any desired C-glycoside.
Notably, when the catalytic quantity was further decreased to
2 mol %, reaction was slow and sluggish (Table 1, entries 6,7).
Nevertheless, acetonitrile as the solvent in the presence of 5 mol %
RuCl3 was found to be optimal requirement for the C-glycosylation
of glycals.
Table 1
RuCl3 catalyzed C-glycosylation of glycal 1a with allyl trimethylsilane (2a) under various conditionsa
Entry
Solvent
Time (h)
Temp (ꢀC)
Conv. (%)b
Yield (%)c
a:b
ratiod
1
2
3
4
CH2Cl2
CH2Cl2
C2H4Cl2
C2H4Cl2
CH3CN
CH3CN
CH3CN
8
16
8
16
0.5
48
16
rt
40
rt
40
rt
rt
60
80
40
80
100
10
d
65
d
60
96
d
52
d
90:10
d
90:10
96:4
d
5
6e
7e
40
60
96:4
Entry 5 represents the best reaction conditions, shown in bold.
a
Reaction conditions: Glycal 1a (1 equiv), allyltrimethylsilane (1.2 equiv) and 5 mol% RuCl3.
b
c
Progress of reaction was monitored by TLC analysis at given time, rt¼room temperature, n. r.¼no reaction.
Isolated yields.
d
e
The
The reactions were performed with 2 mol % of RuCl3.
a/b
ratios were based on the relative integration of anomeric or separable protons (1H NMR spectrum).

88
B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
Table 2
C-glycosylation of glucal 1a with various acceptors under optimized conditiona
Entry
1
Nucleophile
Glycoside
Time (min)
20
Yield (%)b
90
a:b
ratioc
2b
60:40
3b
3c
2
3
2c
40
20
98
47
d
2d
72:28
3d
20
60
35
95
89:11
83:17
3d'
4
5
2e
2f
3e
20
96
88:12
3f
6
7
2g
2h
20
40
88
68
54:46
3g
a
3h
a
All reactions were performed with glucal 1a (1 mmol), 1.2 equiv of acceptor with 5 mol % of RuCl3 in acetonitrile at room temperature.
b
c
Isolated and un-optimized yields.
The a:b
and epimeric ratios were examined by 1H NMR spectroscopy.
corresponding C-glycosyl heteroaromatic (3g) in good yield in a
mixture of ratio 1:1 (Table 2, entry 6). In contrast, the furan (2h)
underwent regioselective C-glycosylation with glucal 1a under
identical conditions to afford C-3-substituted glycal (3h) as the
major product along with a trace amount of the 2,3-unsaturated
C-1-glycoside (Table 2, entry 7).12c
We next attempted the activation of 3,4,6-tri-O-benzyl glucal
(1b) under ruthenium-mediated C-glycosylation. Accordingly, the
glucal 1b was reacted with allyltrimethylsilane (2a) to obtained the
corresponding C-allyl glucoside (3i) in 96% yield with high
anomeric selectivity (Table 3, entry 1). On the other hand, the
C-glycosylation of the trimethylsilyl cyanide (2b) with 1b provided
observed in case of per-acetylated glucal 1a than the benzylated
glucal 1b, which explain that the acetyl group behaves as better
leaving group than benzyl ether.
We next examined the scope and efficiency of current C-glyco-
sylation method in the context of other glycals. Thus, the C-glyco-
sylation reaction of 3,4,6-tri-O-acetyl galactal (1c) with silylated C-
nucleophiles (2ae2c) and silyl enol ether (2e) furnished the desired
2,3-unsaturated C-galactosides (3le3o) in high yields with exclu-
a/b
sive
a-selectivity (Table 3, entries 4e7). Similarly, the Ferrier C-
glycosylation of 3,4-di-O-acetyl xylal (1d) was performed with
silylated nucleophiles (2ae2c) under similar conditions to obtain
the corresponding 2,3-unsaturated C-xylosides (3pe3r) in good
the corresponding glycoside (3j) as mixture of
a:
b
ratio 60:40
yield with high anomeric selectivity in favor of a-anomer (Table 3,
(Table 3, entry 2). Similarly, the glycosylation reaction of 1b with
trimethylsilyl azide (2d) proceeded smoothly to afford the corre-
sponding C-3 glycal azide (3k) as major product in 80% yields along
entries 8e10).
The predominant formation of axial C-glycosides in the case
of galactal could be attributed to a vinylogous anomeric effect, an
allylic effect demonstrate a preferred quasi-axial orientation of
the C3-OAc group in per-acetylated glycals and depends on
with C-1 epimer (3k0) in 16% yield with exclusive
a
selectivity
(Table 3, entry 3). However, relatively faster reaction rate was

B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
89
Table 3
RuCl3 catalyzed C-glycosylation of glycalsa
Entry
1
Glycal
Nucleophile
Glycoside
Time (min)
30
Yield (%)b
96
a
a
:
b
ratioc
only
2a
3i
3j
1b
1b
2
3
2b
2d
40
40
92
80
60:40
67:33
1b
3k
3k'
3l
40
10
16
94
a
a
only
only
4
2a
1c
5
6
7
1c
2b
2c
2e
40
20
60
82
94
90
a
only
3m
3n
1c
1c
d
a
only
3o
3p
8
2a
10
92
95:5
1d
9
1d
2b
2c
10
30
82
88
89:11
3q
3r
10
1d
d
a
All reactions were performed with glycal (1 mmol), 1.2 equiv of acceptor with 5 mol % of RuCl3 in acetonitrile at room temperature.
Isolated and un-optimized yields.
b
c
The a:b
and epimeric ratios were examined by 1H NMR spectroscopy.
conformational equilibrium between 4H545H4, two opposite half-
chair confirmations.12d-f
and flexibility of the current reagent system was successfully
demonstrated for a wide range of substrates to achieve various
functionalized 2,3-unsaturated C-glycosides of significant synthetic
value. In the present C-glycosylation protocol, the use of environ-
mental friendly reagent system and the easy availability of starting
materials are added advantages. We believe that Ru-catalyzed
glycosylation would find its applicability and contribute in
advancing glycochemistry.
3. Conclusions
In summary, we have demonstrated an efficient, convenient and
highly catalytic system for the C-glycosylation of glycals to access C-
glycosides under mild reaction conditions. In addition, the utility

90
B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
4. Experimental
NMR (75 MHz, CDCl3): d 170.6, 170.0, 129.7, 123.5, 115.5, 72.0, 63.7,
62.6, 62.2, 20.8, 20.7; HRMS (ESI): m/z [MþNa]þ calcd for
4.1. General synthesis information, methods and materials
C
11H13O5Naþ: 262.06859; found: 262.06813.
Unless otherwise noted, materials were obtained from com-
mercial suppliers and used without purification. Reactions were
run in screw capped glass vials (4 mL) stirred with Teflon®-coated
magnetic stir bars. Moisture and air-sensitive reactions were per-
formed in flame-dried round bottom flasks, fitted with rubber septa
or glass gas adapters, under a positive pressure of nitrogen. Mois-
ture and air-sensitive liquids or solutions were transferred via
nitrogen-flushed syringe. Concentration of solvents was accom-
plished by rotary evaporation using a Büchi rotary evaporator at
temperatures between 35 ꢀC and 50 ꢀC. Analytical TLC was per-
formed using Whatman 250 micron aluminum backed UV F254
precoated silica gel flexible plates. Subsequent to elution, ultravi-
olet illumination at 254 nm allowed for visualization of UV active
materials. Staining with p-anisaldehyde, basic potassium perman-
ganate solution, or Molisch's reagents allowed for further visuali-
zation. Proton nuclear magnetic resonance spectra (1H NMR) were
recorded on Avance 300 or Avance 500 MHz nuclear magnetic
resonance spectrometers. Chemical shifts for 1H NMR spectra are
4.2.3. Compound (3b-b)
Semi solid; [
a
]
25 þ277.27 (c 1.1, CHCl3); IR (CHCl3, cmꢁ1): 2954,
D
2922, 2852,1745,1462,1372,1217, 1044, 973, 910, 770, 667; 1H NMR
(500 MHz, CDCl3):
d
6.05 (dt, J¼10.4, 2.6 Hz, 1H, H-3), 5.93 (dt,
J¼10.2, 1.8 Hz, 1H, H-2), 5.32 (dq, J¼8.3, 2.0 Hz, 1H, H-4), 5.12 (dd,
J¼2.8, 2.0 Hz, 1H, H-1), 4.28 (dd, J¼9.5, 2.8 Hz, 1H, Ha-6), 4.20 (dd,
J¼9.5, 2.8 Hz, 1H, Hb-6), 3.82 (ddd, J¼6.0, 2.8 Hz, 1H, H-5), 2.12 (s,
3H, CH3COO), 2.10 (s, 3H, CH3COO); 13C NMR (75 MHz, CDCl3):
d
170.7, 170.0, 128.7, 124.2, 115.7, 74.4, 63.5, 62.9, 62.5, 20.8, 20.7;
HRMS (ESI): m/z [MþNa]þ calcd for C11H13O5Naþ: 262.06859;
found: 262.06813.
4.2.4. Compound (3c)
Colorless oil; [
a
]
25 þ62.50 (c 1.2, CHCl3); IR (CHCl3, cmꢁ1): 3020,
D
1736, 1371, 1215, 1046, 1027, 744, 621; 1H NMR (300 MHz, CDCl3):
d
5.96 (dt, J¼11.9, 1.7 Hz, 1H, H-3), 5.76 (dt, J¼12.5, 2.1 Hz, 1H, H-2),
5.27 (m, 1H, H-4), 4.26e4.15 (m, 4H, Hab-1, Hab-6), 3.74 (ddd, J¼8.5,
5.7, 3.2 Hz, 1H, H-5), 2.11 (s, 3H, CH3COO), 2.09 (s, 3H, CH3COO). 13
C
reported as
methylsilane (
standard or tetramethylsilane itself: chloroform-d (
d
in units of parts per million (ppm) relative to tetra-
0.0) using the residual solvent signal as an internal
7.26, singlet).
NMR (75 MHz, CDCl3):
d 170.7, 170.2, 129.3, 124.1, 73.7, 65.1, 65.0,
d
63.1, 20.9, 20.7; HRMS (ESI): m/z [MþNa]þ calcd for C10H14O5Naþ:
d
237.07334; found: 237.07311.
The number of protons (n) for a given resonance is indicated by nH.
IR spectra were recorded on Bruker Alpha spectrometer and mass
analyses (ESI): were performed using a Finnegan MAT 1020 mass
spectrometer operating at 70 eV.
4.2.5. Compound (3d C-3 isomer)/3d0 C-1 isomer)
Colorless oil; IR (CHCl3, cmꢁ1): 3020, 2928, 2103, 1742, 1646,
1370, 1217, 1088, 1049, 910, 771, 667; 1H NMR (500 MHz, CDCl3):
d
6.54 (d, J¼6.0 Hz,1H, H-1, C-3,
C-3,
), 6.04 (ddd, J¼10.4, 3.2 Hz, 0.09H, H-2, C-1,
1.5 Hz, 0.74H, H-3, C-1,
), 5.86 (dt, J¼10.0, 1.0 Hz, 0.09H, H-3, C-1,
), 5.57 (br s, 0.74H, H-1,
), 5.33 (dq, J¼9.6, 1.7 Hz, 0.74H, H-4, C-1, ), 5.28 (m, 0.09H, H-
), 5.17 (dd, J¼9.0, 7.3 Hz, 0.4H, H-2, C-3, ), 5.09 (dd, J¼10.5,
4.3 Hz, 1H, H-2, C-3, ), 5.01e4.97 (m, 0.09H, H-4, C-1, ), 4.90 (t,
),
a
), 6.51 (dd, J¼6.0, 1.8 Hz, 0.4H, H-1,
4.2. General procedure for the RuCl3-catalyzed C-glycosylation
b
b
), 5.95 (dt, J¼10.2,
a
To a stirred solution of glycal (1 equiv) and acceptor or carbon
nucleophile (1.2 equiv) in anhydrous acetonitrile (2 mL/mmol)
under an atmosphere of argon was added RuCl3 (5 mol %) at room
temperature. The reaction mixture was stirred until the complete
consumption of the starting material (glycal). The solvent was
concentrated in vacuo, the crude residue was re-dissolved in
dichloromethane and loaded on a silica gel column. The product
was purified by silica gel chromatography using Hexane/EtOAc to
afford the 2,3-unsaturated-C-glycosides in excellent yields. All the
products were confirmed by IR, 1H NMR, 13C NMR and MS/HRMS
spectroscopy, and overall spectroscopic data were in complete
agreement with assigned structures and also compared with
literature data.
b
C-1,
1, C-1,
), 5.78 (ddd, J¼7.3, 2.9 Hz, 0.74H, H-2, C-1,
a
a
a
b
b
a
b
J¼6.0 Hz, 1H, H-4, C-3,
a
), 4.81 (dd, J¼6.1, 2.6 Hz, 0.4H, H-4, C-3,
b
4.38 (dd, J¼12.5, 4.9 Hz, 1.4H, Ha-6, C-3), 4.32 (dd, J¼12.4, 2.3 Hz,
1.4H, Hb-6, C-3), 4.29e4.06 (m, 4H, Hab-6, C-1, H-5), 4.02e3.99 (m,
0.09H, H-5, C-1,
(125 MHz, CDCl3):
b
), 2.15e2.09 (s, 3H, 4 isomers, CH3COO); 13C NMR
d
170.7, 170.5, 170.1, 169.6, 146.9 (C-3 major),
145.7 (C-3 minor), 129.6, 126.3, 98.1 (C-3 minor), 96.5 (C-3 major),
84.9 (C-1 major), 74.3 (C-3 minor), 70.6 (C-3 major), 68.8 (C-1
major), 68.0 (C-3 major), 67.5 (C-3 minor), 64.5 (C-1 major), 62.5 (C-
1 major), 61.8 (C-3 major), 61.4 (C-3 minor), 57.6 (C-3 minor), 53.3
(C-3 major), 20.9, 20.7, 20.6, 20.5; HRMS (ESI): m/z [MþNa]þ calcd
for C10H13N3O5Naþ: 278.07474; found: 278.07431.
4.2.1. Compound (3a)
25
Colorless viscous oil; [
a
]
þ120.37 (c 2.7, CHCl3); IR (CHCl3,
D
cmꢁ1): 2923, 2852, 1737, 1435, 1369, 1222, 1044, 971, 913, 750, 666;
1H NMR (300 MHz, CDCl3):
d
5.95e5.78 (m, 3H, H-3, H-2, CH]CH2),
4.2.6. Compound (3e)
5.14e5.11 (m, 3H, H-4, CH]CH2), 4.28 (m,1H, H-1), 4.22 (dd, J¼11.9,
6.4 Hz, 1H, Ha-6), 4.16 (dd, J¼11.9, 3.6 Hz, 1H, Hb-6), 3.97 (td, J¼6.2,
3.6 Hz, 1H, H-5), 2.51e2.29 (m, 2H, Hab-1), 2.09 (s, 6H, 2ꢂCH3COO);
Colorless oil; [
a
]
25 þ87.50 (c 1.2, CHCl3); IR (CHCl3, cmꢁ1): 3019,
D
2933, 1736, 1370, 1214, 748, 667; 1H NMR (500 MHz, CDCl3):
d 6.14
(dt, J¼10.5, 1.5 Hz, 1H, H-3, major), 6.04 (d, J¼10.5 Hz, 1H, H-3,
minor), 5.93 (ddd, J¼4.1, 1.8 Hz, 1H, H-2, minor), 5.78 (ddd, J¼2.6,
2.1 Hz, 1H, H-2, major), 5.13 (m,1H, H-4, major), 4.99 (br s, 1H, H-1,
minor), 4.76 (m, 1H, H-4, minor), 4.46 (dd, J¼8.9, 1.9 Hz, 1H, H-1,
major), 4.29e4.06 (m, 5H, Hab-6, H-5, minor), 3.85 (m, 1H, H-5,
major), 2.76 (m, 0.65H), 2.63 (m, 1H), 2.46e2.31 (m, 4H), 2.17 (m,
1H), 2.11e2.08 (3H, 2 isomers, CH3COO), 2.04e1.90 (m, 3H),
1.74e1.45 (m, 5H), 0.90e0.82 (m, 2H); 13C NMR (75 MHz, CDCl3):
13C NMR (75 MHz, CDCl3):
d 170.5, 170.1, 133.8, 132.6, 123.5, 117.4,
(74.1-b), (74.0-b), 71.1, 69.5, (65.4-b), 64.8, (63.5-b), 62.7, 37.6, 20.8,
20.6; HRMS (ESI): m/z [MþNa]þ calcd for C13H18O5Naþ: 277.10464;
found: 277.10428.
4.2.2. Compound (3b-a)
Semi solid; [
a]
25 þ150.00 (c 1.0, CHCl3); IR (CHCl3, cmꢁ1): 2954,
D
2922, 2852,1745,1462,1372,1217,1044, 973, 910, 770, 667; 1H NMR
d 210.9 (major), 210.5 (minor), 170.6, 170.4, 170.2, 132.9 (major),
(500 MHz, CDCl3):
d
6.04 (dt, J¼10.2, 2.0 Hz, 1H, H-3), 5.90 (ddd,
132.0 (minor), 123.4 (major), 122.8 (minor), 71.7 (minor), 70.1
(major), 69.9 (major), 68.3 (minor), 64.8 (major), 64.3 (minor), 62.7
(major), 61.8 (minor), 53.6 (minor), 53.2 (major), 42.6 (major), 41.7,
30.1 (major), 28.5 (minor), 27.8 (major), 27.4 (minor), 24.5, 24.0,
J¼6.7, 2.0 Hz, 1H, H-2), 5.35 (dq, J¼9.2, 2.0 Hz, 1H, H-4), 5.08 (dt,
J¼3.4, 1.7 Hz, 1H, H-1), 4.26 (d, J¼4.0 Hz, 2H, Hab-6), 4.04 (dt, J¼9.2,
4.0 Hz, 1H, H-5), 2.12 (s, 3H, CH3COO), 2.11 (s, 3H, CH3COO); 13C

B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
91
20.9, 20.7; HRMS (ESI): m/z [MþNa]þ calcd for C16H22O6Naþ:
4.2.11. Compound (3j)
25
333.13086; found: 333.13018.
Colorless viscous oil; [
a]
þ44.737 (c 3.8, CHCl3); IR (CHCl3,
D
cmꢁ1): 2922, 2853, 1724, 1453, 1360, 1272, 1097, 908, 741, 698; 1H
4.2.7. Compound (3f)
NMR (500 MHz, CDCl3):
1.7H, H-3), 5.79 (dt, J¼10.2, 1.8 Hz, 0.7H, H-2,
3.5, 1.7 Hz, 1H, H-2,
d
7.36e7.22 (m, 17H, Ph), 6.17e6.11 (m,
), 5.79 (ddd, J¼6.7,
), 5.03 (dd, J¼2.6, 2.1 Hz, 0.7H, H-1, ), 5.02 (m,
), 4.68e4.45 (m, 6H, CH2Ph), 4.23 (ddd, J¼10.8, 9.0, 1.8 Hz,
), 4.05 (m, 0.7H, H-4, ),
), 3.85 (dt, J¼8.9, 2.8 Hz,1H, H-5,
), 3.67 (dd, J¼7.8, 5.3 Hz, 1H, Hb-6,
), 3.65 (dd, J¼5.5, 2.0 Hz, 0.7H, Hb-6,
); 13C NMR (75 MHz, CDCl3):
137.6, 137.3, 131.3, 130.0, 128.5e127.6, 122.8, 121.9, 116.3, 116.2,
Yellowish oil; [
a
]
D
25 þ66.00 (c 3.0, CHCl3). IR (CHCl3, cmꢁ1): 2981,
b
2928, 1738, 1717, 1445, 1221, 1037, 772, 604; 1H NMR (500 MHz,
a
b
CDCl3):
d
6.04 (m, 1H, H-2, major), 5.95 (dt, J¼10.5, 1.7 Hz, 1H, H-2,
1H, H-1,
1H, H-4,
a
a
minor), 5.91e5.83 (m, 1H, H-3, major), 5.81e5.77 (m, 1H, H-3 mi-
nor), 5.26 (m, 1H, H-1 major), 5.18e5.11 (m, 1H, H-1, minor),
4.92e4.79 (m, 2H, H-4, both isomer), 4.32e4.05 (m, 6H, H-5,
eOCH2CH3, both isomer), 3.94e3.88 (m, 4H, Hab-6, both isomer),
3.76e3.71 (m, 2H, H-10, both isomer), 2.32 (s, 3H, CH3, minor), 2.30
(s, 3H, CH3, major), 2.09e2.06 (s, 3H, 4 isomers, CH3COO), 1.30e1.27
b
a
3.76e3.70 (m, 2.4H, Ha-6, H-5,
b
a
b
d
77.2, 74.2, 73.5, 73.4, 71.8, 68.7, 67.9, 63.2, 62.9; HRMS (ESI): m/z
[MþNa]þ calcd for C21H21NO3Naþ: 358.14191; found: 358.14095.
(m, 4H, CH3, both isomer); 13C NMR (75 MHz, CDCl3):
d 201.1, 200.0,
170.5, 170.1, 166.6, 166.5, 130.1, 129.9, 129.7, 129.6, 126.6, 126.8,
125.5, 125.4, 74.3, 74.2, 73.5, 73.0, 70.2, 70.0, 64.8, 64.7, 64.4, 64.3,
63.3, 63.1, 63.0, 62.9, 62.8, 62.4, 62.4, 61.6, 61.4, 20.8, 20.5, 13.9;
HRMS (ESI): m/z [MþNa]þ calcd for C16H22O8Naþ: 365.12069;
found: 365.12014.
4.2.12. Compound (3k C-3 isomer)/3k0 C-1 isomer)
Semi solid; IR (CHCl3, cmꢁ1): 2919, 2864, 2097, 1645, 1452, 1363,
1233, 1107, 734, 696; 1H NMR (300 MHz, CDCl3):
d
7.35e7.23 (m,
), 6.48 (dd, J¼6.0, 1.7 Hz,
), 6.12 (dt, J¼10.0, 1.3 Hz, 0.3H, H-3, C-1, ), 5.70
(ddd, J¼10.2, 2.6, 0.6 Hz, 1H, H-2, C-1, ), 5.33 (br s, 0.3H, H-1, C-1,
18H, Ph), 6.52 (d, J¼5.6 Hz, 1H, H-1, C-3,
a
0.5H, H-1, C-3,
b
a
a
4.2.8. Compound (3g
a
/
b
)
a
), 4.84 (d, J¼10.8 Hz, 0.5H, H-2, C-3, b), 4.79 (t, J¼5.6 Hz,1H, H-2, C-
25
Yellowish oil; [
a
]
þ121.73 (c 2.3, CHCl3); IR (CHCl3, cmꢁ1):
D
3, a), 4.71e4.43 (m, 6.3H, CH2Ph), 4.21 (ddd, J¼9.5, 3.6, 1.7 Hz, 0.5H,
H-4, C-3, b), 4.11e4.04 (m, 3.3H, H-4), 3.97e3.92 (m, 1.8H, Ha-6),
3019, 1738, 1431, 1214, 1047, 742, 667; 1H NMR (500 MHz, CDCl3):
d
7.34 (d, J¼6.1 Hz, 1H, Ph,
J¼3.5 Hz, 0.85H, Ph, ), 7.03 (d, J¼3.2 Hz, 1H, Ph,
1H, Ph, ), 6.99e6.97 (m, 0.85H, Ph,
), 6.21 (ddd, J¼10.4, 3.4 1.8 Hz,
1H, H-2, ), 5.97 (dt, J¼10.2,
), 6.00 (dt, J¼10.2, 1.7 Hz, 0.85H, H-2,
2.0 Hz, 1H, H-3, ), 5.54 (d,
), 5.86 (dt, J¼10.2, 2.1 Hz, 0.85H, H-3,
J¼2.1 Hz, 1H, H-1, ), 5.50 (d, J¼1.5 Hz, 0.85H, H-1, ), 5.41 (dq,
J¼9.0, 2.8 Hz, 0.85H, H-4, ), 5.35 (dq, J¼8.5, 2.0 Hz, 1H, H-4, ), 4.29
(dd, J¼12.2, 2.4 Hz, 0.85H, Ha-6, ), 4.24 (dd, J¼12.2, 5.5 Hz, 1H, Ha-
6, ), 4.11 (dd, J¼12.1, 2.6 Hz,
), 4.19 (dd, J¼12.2, 6.0 Hz, 0.85H, Hb-6,
1H, Hb-6, ), 3.87 (ddd,
), 3.93 (ddd, J¼8.9, 6.0, 2.4 Hz, 0.85H, H-5,
J¼8.4, 5.5, 2.8 Hz, 1H, H-5, ), 2.11e2.08 (s, 3H, 2 isomers, CH3COO);
13C NMR (125 MHz, CDCl3):
142.8 ( ), 141.9 ( ), 131.8 ( ), 130.1 (
126.4 ( ), 126.2 ( ), 125.9 (
70.0 ( ), 68.5 ( ), 65.2 (
a
), 7.30 (d, J¼6.1 Hz, 0.85H, Ph,
b), 7.05 (d,
), 7.02e7.00 (m,
3.82e3.73 (m, 4H, Hb-6, H-5); 13C NMR (75 MHz, CDCl3):
d 147.3,
b
a
146.0, 137.8, 137.2, 131.3, 128.4, 128.4, 128.4, 128.3, 128.0, 128.0,
127.9, 127.8, 127.7, 127.6, 124.8, 98.2, 95.8, 84.9, 77.1, 74.5, 74.2, 73.4,
75.5, 73.4, 73.2, 73.2, 72.0, 71.3, 71.1, 69.4, 68.3, 68.0, 60.7, 53.4;
HRMS (ESI): m/z [MþNa]þ calcd for C20H21N3O3Naþ: 374.14751;
found: 374.14733.
a
b
a
b
a
b
a
b
b
a
b
a
b
4.2.13. Compound (3l)
25
a
b
Colorless viscous oil; [
a
]
ꢁ145.00 (c 4.0, CHCl3); IR (CHCl3,
D
a
cmꢁ1): 2966, 2931, 1744, 1373, 1252, 1165, 1072, 1037, 846. 1H NMR
(500 MHz, CDCl3):
d
170.9 (
b
), 170.7 (
), 126.9 (
), 125.6 ( ), 125.4 (
), 63.5 ( ), 62.9 (
a
a
), 170.3 ( ), 170.2 (
), 126.7 ( ), 126.5 (
), 74.8 (a), 72.6 (
a
a
b
b
b
),
),
),
d
6.06 (dd, J¼10.4, 2.9 Hz, 1H, H-3), 6.06 (ddd,
b
a
a
a
b
a
J¼10.2, 5.0, 2.0 Hz, 1H, H-2), 5.89e5.81 (m, 1H, HC]CH2), 5.16e5.11
(m, 2H, CH]CH2), 5.08 (dd, J¼5.0, 2.6 Hz, 1H, H-4), 4.36 (ddd,
J¼10.7, 5.3, 2.3 Hz, 1H, H-1), 4.20 (dd, J¼5.7, 2.9 Hz, 2H, Hab-6),
4.15e4.12 (m, 1H, H-5), 2.44 (m, 1H, Ha-10), 2.30 (m, 1H, Hb-10), 2.08
(s, 3H, CH3COO), 2.07 (s, 3H, CH3COO); 13C NMR (125 MHz, CDCl3):
b
b
b
a
b
b
), 65.0 (
a
b
a
), 21.0, 20.8, 20.7;
HRMS (ESI): m/z [MþNa]þ calcd for C14H16O5SNaþ: 319.06107;
found: 365.06035.
d
170.6, 170.3, 134.7, 133.8, 121.9, 117.5, 72.1, 67.9, 63.7, 62.8, 36.6,
4.2.9. Compound (3h)
20.8, 20.7; HRMS (ESI): m/z [MþNa]þ calcd for C13H18O5Naþ:
25
Brownish oil; [
a
]
D
þ504.16 (c 1.2, CHCl3); IR (CHCl3, cmꢁ1):
277.10464; found: 277.10470.
2923, 2852, 1740, 1653, 1369, 1220, 1050, 771, 744, 602; 1H NMR
(500 MHz, CDCl3):
d
7.37 (d, J¼1.1 Hz, 1H, Ph), 6.53 (dd, J¼6.0, 1.5 Hz,
4.2.14. Compound (3m)
1H, H-1), 6.34 (dd, J¼3.1, 1.8 Hz, 1H, Ph), 6.14 (d, J¼3.2 Hz, 1H, Ph),
5.06 (dd, J¼9.9, 16.1 Hz, 1H, H-4), 4.81 (t, J¼5.7 Hz, 1H, H-2),
4.31e4.29 (m, 2H, Hab-6), 4.15 (ddd, J¼9.9, 4.6, 2.8 Hz, 1H, H-5), 4.03
(dt, J¼6.3, 1.4 Hz, 1H, H-3), 2.09 (s, 3H, CH3COO), 1.99 (s, 3H,
Semi solid; [
a]
25 ꢁ356.66 (c 1.5, CHCl3); IR (CHCl3, cmꢁ1): 2966,
D
2931, 1744, 1373, 1072, 1037, 846; 1H NMR (500 MHz, CDCl3):
d
6.27
(ddd, J¼10.0, 5.7, 2.1 Hz, 1H, H-3), 6.06 (dd, J¼10.0, 3.8 Hz, 1H, H-2),
5.17e5.14 (m, 2H, H-4, H-1), 4.20 (m, 3H, Hab-6, H-5), 2.11 (s, 3H,
CH3COO); 13C NMR (125 MHz, CDCl3):
d 170.7, 169.9, 153.3, 143.9,
CH3COO), 2.09 (s, 3H, CH3COO); 13C NMR (75 MHz, CDCl3):
d 170.2,
142.4, 110.2, 109.0, 98.3, 70.7, 67.7, 62.7, 33.7, 20.7, 20.7; HRMS (ESI):
169.7, 126.3, 125.9, 115.1, 71.6, 62.4, 61.9, 61.9, 20.4, 20.4; HRMS
(ESI): m/z [MþNa]þ calcd for C11H13O5Naþ: 262.06859; found:
262.06812.
m/z [MþNa]þ calcd for C14H16O6Naþ: 303.08391; found: 303.08327.
4.2.10. Compound (3i)
25
Colorless oil; [
a]
þ73.529 (c 3.4, CHCl3); IR (CHCl3, cmꢁ1):
D
3064, 3030, 2924, 2859,1729,1453,1363,1305,1213,1092, 994, 914,
4.2.15. Compound (3n)
737, 698; 1H NMR (300 MHz, CDCl3):
d
7.36e7.24 (m, 10H, Ph),
Colorless oil; [
a
]
D
25 ꢁ33.33 (c 1.5, CHCl3); IR (CHCl3, cmꢁ1): 3020,
5.94e5.77 (m, 3H, H-3, H-2, HC]CH2), 5.14e5.05 (m, 2H, HC]CH2),
4.59 (dd, 2H, J¼12.1, 5.9 Hz, 2H, CH2Ph), 4.52 (dd, 2H, J¼13.8,
11.7 Hz, 2H, CH2Ph), 4.24 (dt, J¼7.7, 5.9, 1.9 Hz, 1H, H-1), 4.00 (dd,
J¼7.2, 1.5 Hz, 1H, H-4), 3.82 (m, 1H, H-5), 3.69e3.65 (m, 2H, Hab-6),
2.48 (m, 1H, Ha-10), 2.33 (m, 1H, Hb-10); 13C NMR (75 MHz, CDCl3):
1736, 1371, 1215, 1088, 1048, 744, 666; 1H NMR (500 MHz, CDCl3):
d
6.11 (ddd, J¼11.8, 3.7, 1.5 Hz, 1H, H-3), 6.04e5.98 (m, 1H, H-2), 5.11
(dt, J¼85.3, 2.1 Hz, 1H, H-4), 4.34 (ddd, J¼17.2, 3.5, 1.8 Hz, 1H, Ha-1),
4.26e4.17 (m, 3H, Hb-1, Hab-6), 3.89 (ddd, J¼7.3, 5.0, 2.3 Hz, 1H, H-
5), 2.09 (s, 3H, CH3COO), 2.09 (s, 3H, CH3COO); 13C NMR (125 MHz,
d
138.2, 134.5, 131.1, 138.3, 128.3, 127.9, 127.8, 127.7, 127.5, 125.6,
CDCl3): d 170.7, 170.4, 132.3, 122.0, 73.6, 65.6, 64.2, 63.2, 20.7, 20.7;
117.2, 73.3, 72.0, 71.3, 71.0, 69.9, 69.2, 38.0; HRMS (ESI): m/z
HRMS (ESI): m/z [MþNa]þ calcd for C10H14O5Naþ: 237.07334;
[MþNa]þ calcd for C23H26O3Naþ: 373.17796; found: 373.17721.
found: 237.07347.

92
B. Srinivas et al. / Carbohydrate Research 406 (2015) 86e92
Angew Chem Int Ed 2001;40:1576e624;
(d) Somsak L. Chem Rev 2001;101:81e136;
(e) Dwek RA. Chem Rev 1996;96:683e720;
4.2.16. Compound (3o)
ꢀ
Colorless oil; [
a
]
25 þ88.42 (c 3.3, CHCl3); IR (CHCl3, cmꢁ1): 3020,
D
1737, 1371, 1215, 1047, 744, 667; 1H NMR (300 MHz, CDCl3):
d 6.29
(f) Sharma GVM, RadhaKrishna P. Curr Org Chem 2004;8:1187e209;
(g) Dondoni A, Marra A. Chem Rev 2000;100:4395e422;
(h) Ritchie GE, Moffatt BE, Sim RB, Morgan BP, Dwek RA, Rudd PM. Chem Rev
2002;102:305e20;
(i) Hanessian S, Lou B. Chem Rev 2000;100:4495e538.
2. (a) Lewis MD, Cha JK, Kishi Y. J Am Chem Soc 1982;104:4976e8;
(b) Paterson I, Keown LE. Tetrahedron Lett 1997;38:5727e30;
(c) Horita K, Sakurai Y, Nagasawa M, Hachiya S, Yonemitsu O. Synlett 1994:
43e5;
(dd, J¼10.4, 3.2 Hz, 1H, H-3, major), 6.04 (dd, J¼11.9, 1.5 Hz, 1H, H-3,
minor), 5.97e5.90 (m, 2H, H-2), 5.21 (br s, 1H, H-1, minor), 5.07 (m,
1H, H-1, major), 4.80 (d, J¼6.6 Hz,1H, H-4, minor), 4.49 (d, J¼9.8 Hz,
1H, H-4, major), 4.26e4.18 (m, 5H, Hab-6, H-5), 401e3.96 (m, 1H, H-
5, major), 2.78e2.60 (m, 2H), 2.51e2.26 (m, 5H), 2.13e2.02 (s, 12H,
2 isomers, CH3COO), 1.98e1.55 (m, 12H); 13C NMR (75 MHz, CDCl3):
d
211.0, 210.3, 170.7, 170.5, 170.4,170.3, 134.7, 131.4, 123.4, 121.6, 71.1,
(d) Fraser-Reid B. Acc Chem Res 1985;18:347e54;
(e) Faul MM, Huff BE. Chem Rev 2000;100:2407e74.
3. (a) Postema MHD, Piper JL, Komanduri V, Liu L. Angew Chem Int Ed 2004;43:
2915e8;
69.5, 69.1, 68.5, 64.0, 63.7, 62.9, 61.6, 53.4, 52.4, 42.6, 41.3, 30.6, 28.8,
27.9, 27.5, 24.4, 23.4, 20.8, 20.8, 20.7, 20.6; HRMS (ESI): m/z
[MþNa]þ calcd for C16H22O6Naþ: 333.13086; found: 333.13085.
(b) Piper JL, Postema MHD. J Org Chem 2004;69:7395e8.
4. (a) Suhadolnik RJ. Nucleoside antibiotics. New York: Wiley-Interscience; 1970;
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ꢁ
(b) Stambaský J, Hocek M, Kocovský P. Chem Rev 2009;109:6729e64.
5. Watanabe T, Hiral G, Kato M, Hashizume D, Miyagi T, Sodeka M. Org Lett
2008;10:4167e70.
4.2.17. Compound (3p)
25
Colorless viscous oil; [
a
]
þ125.00 (c 1.6, CHCl3); IR (CHCl3,
D
cmꢁ1): 2984, 2924, 2853, 1743, 1373, 1222, 1070, 1045, 1004, 917,
891, 864, 772; 1H NMR (500 MHz, CDCl3):
6.02 (d, J¼11.9 Hz,
0.06H, H-3,
), 5.92 (dt, J¼10.4, 1.2 Hz, 1H, H-3), 5.87e5.79 (m, 2H,
H-2, CH]CH2), 5.25 (m, 1H, H-4), 5.15e5.09 (m, 2H, CH]CH2), 5.00
(m, 0.06H, H-4, ), 4.31 (m, 0.06H, H-1, ), 4.20e4.17 (m, 1H, H-1),
4.13 (dd, J¼11.4, 5.0 Hz, 1H, Ha-5), 3.76 (dd, J¼10.9, 1.8 Hz, 0.06H,
Hb-5,
), 3.54 (dd, J¼11.4, 6.7 Hz, 1H, Hb-5), 2.38e2.26 (m, 2H, Hab
10), 2.09 (s, 0.18H, CH3COO, ), 2.07 (s, 3H, CH3COO); 13C NMR
170.5, 133.8, 133.4, 124.4, 117.5, 73.0, 65.1, 64.9,
6. (a) Weatherman RV, Mortell KH, Chervenak M, Kiessling LL, Toone EJ.
Biochemistry 1996;35:3619e24;
(b) Sutherlin DP, Stark TM, Hughes R, Armstrong RW. Org Chem 1996;61:
8350e4;
(c) Zou W. Curr Top Med Chem 2005;5:1363e91.
7. (a) Ferrier RJ. J Chem Soc 1964:5443e9;
(b) Ciment DM, Ferrier RJ. J Chem Soc C 1966:441e5;
(c) Ferrier RJ, Sankey GH. J Chem Soc C 1966:2345e9.
8. (a) Ferrier RJ, Prasad N. J Chem Soc C 1969:570e5;
(b) Ferrier RJ, Prasad N. J Chem Soc C 1969:581e6;
d
b
b
b
b
-
b
ꢀ
ꢀ
(c) Review: Gomez AM, Lobo F, Uriel C, Lopez JC Eur J Org Chem 2013;32:
7221e62;
(125 MHz, CDCl3):
38.6, 21.0.
d
(d) Ansari AA, Lahiri R, Vankar YD. ARKIVOC 2013;(Pt. ii):316e62.
9. (a) Godage HY, Fairbanks AJ. Tetrahedron Lett 2000;41:7589e93;
(b) Kim H, Men H, Lee C. J Am Chem Soc 2004;126:1336e7;
(c) Zeng J, Xiang S, Cai S, Liu X-W. Angew Chem Int Ed 2013;125:1576e80;
(d) Kusunuru AK, Tatina M, Yousuf SK, Mukherjee D. Chem Commun 2013;49:
10154e6;
(e) Isobe M, Phoosaha W, Saeeng R, Kira K, Yenjai C. Org Lett 2003;5:4883e5;
(f) Vieira AS, Fiorante PF, Hough TLS, Ferreira FP, Lüdtke DS, Stefani HA. Org Lett
2008;10:5215e8;
(g) Lubin-Germain N, Hallonet AH, Huguenot F, Palmier S, Uziel J, Aüge J. Org
Lett 2007;9:3679e82.
10. (a) Wellington KW, Benner SA. Nucleosides Nucleotides Nucleic Acids 2006;25:
1309e33;
4.2.18. Compound (3q)
25
Colorless oil; [
a
]
þ184.00 (c 1.6, CHCl3); IR (CHCl3, cmꢁ1):
D
3020, 2922, 2851, 1739, 1463, 1373, 1215, 750, 667; 1H NMR
(500 MHz, CDCl3):
J¼10.4, 2.3 Hz, 0.12H, H-3,
(ddd, J¼11.8, 6.1, 2.5 Hz, 0.12H, H-2,
5.09e5.05 (m, 2H, H-4, H-1), 4.97 (m, 0.12H, H-4,
d
6.22 (ddd, J¼10.0, 7.2, 1.5 Hz, 1H, H-3), 6.11 (dt,
), 6.06 (dd, J¼10.6, 3.8 Hz, 1H, H-2), 5.94
), 5.28 (m, 0.12H, H-1, ),
), 4.10e4.08 (m,
b
b
b
b
2H, Hab-5), 3.83 (dd, J¼9.7, 5.7 Hz, 0.12H, Hb-5), 2.10 (s, 3H,
CH3COO); 13C NMR (75 MHz, CDCl3):
d 170.1, 126.5, 125.8, 115.4,
(b) Lei M, Gao L, Yang J-S. Tetrahedron Lett 2009;50:5135e8;
(c) Li H-H, Ye X-S. Org Biomol Chem 2009;7:3855e61;
(d) Ramnauth J, Poulin O, Rakhit S, Maddaford SP. Org Lett 2001;3:2013e5;
(e) Ramnauth J, Poulin O, Bratovanov SS, Rakhit S, Maddaford SP. Org Lett
2001;3:2571e3;
65.3, 62.2, 61.5, 20.7.
4.2.19. Compound (3r)
25 þ69.44 (c 1.8, CHCl3); IR (CHCl3, cmꢁ1): 2920,
(f) Xiang S, Cai S, Zeng J, Liu X-W. Org Lett 2011;13:4608e11;
(g) Bai Y, Kim LMH, Liao H, Liu X-W. J Org Chem 2013;78:8821e5.
11. (a) Narasimha G, Srinivas B, RadhaKrishna P, Kashyap S. Synlett 2014:523e6;
(b) Srinivas B, Narasimha G, RadhaKrishna P, Kashyap S. Synthesis 2014:
1191e6;
Colorless oil; [
a
]
D
2851, 1725, 1462, 1378, 1283, 1215, 1123, 1074, 754, 667; 1H NMR
(300 MHz, CDCl3):
d
6.08 (dt, J¼10.2, 2.1 Hz, 1H, H-3), 5.96e5.90 (m,
1H, H-2), 5.09 (m, 1H, H-4), 4.21 (dt, J¼17.0, 1.8 Hz, 1H, Ha-1), 4.09
(dd, J¼17.0, 2.1 Hz, 1H, Hb-1), 3.95 (dd, J¼12.5, 1.7 Hz,1H, Ha-5), 3.81
(dd, J¼12.5, 3.2 Hz, 1H, Hb-5), 2.10 (s, 3H, CH3COO); 13C NMR
(c) Srinivas B, Reddy TR, RadhaKrishna P, Kashyap S. Synlett 2014:1325e9;
(d) Chittela S, Reddy TR, RadhaKrishna P, Kashyap S. RSC Adv 2014;4:
46327e31;
(e) Reddy TR, Chittela S, Kashyap S. Tetrahedron 2014;70:9224e9.
12. (a) Ansari AA, Reddy YS, Vankar YD. Beilstein J Org Chem 2014;10:300e6;
(b) Kawabata H, Kubo S, Hayashi M. Carbohydr Res 2001;333:153e8;
(c) Yadav JS, Reddy BVS, Raman JV, Niranjan N, Kumar SK, Kunwar AC.
Tetrahedron Lett 2002;43:2095e8;
(75 MHz, CDCl3):
d 170.7, 132.2, 122.4, 67.7, 65.0, 64.8, 21.2.
Acknowledgments
(d) Curran DP, Suh Y-G. J Am Chem Soc 1984;106:5002e4;
(e) Denmark SE, Dappen MS. J Org Chem 1984;49:798e806;
(f) Katritzky AR, Steel PJ, Danisenko SN. Tetrahedron 2001;57:3309e14.
13. (a) Nicolaou KC, Duggan ME, Hwang CK, Somers PK. J Chem Soc Chem Commun
1985:1359e62;
This research is supported by Department of Science and Tech-
nology, New Delhi (GAP0397 & 0471). The authors are grateful to the
Director CSIR-IICT for providing necessary infrastructure. B.S ac-
knowledges a UGC Fellowship.
(b) Wincott FE, Danishefsky SJ, Schutte G. Tetrahedron Lett 1987;28:4951e4;
(c) Hanessian S. Total synthesis of natural products: the chiron approach. Oxford:
Pergamon Press; 1984;
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