A substrate controlled, very highly diastereoselective Morita-Baylis- Hillman reaction: A remote activation of the diastereofacial selectivity in the synthesis of C-3-branched deoxysugars

Article abstract of DOI:10.1016/j.tet.2004.09.086

The Morita-Baylis-Hillman (MBH) reaction of p-nitrobenzaldehyde with C (6) acyl protected enuloside 1 in the presence of TiCl₄/TBAI yielded highly diastereoenriched C-3-branched deoxysugar derivative or MBH adduct 1′a in high yield, while reactions of unprotected enuloside 2a and C (6) alkyl protected enulosides 2d-e with p-nitrobenzaldehyde under the same conditions afforded the adducts 2′a and 2′d-e, respectively, in low yield with moderate selectivity. Several representative aromatic and aliphatic aldehydes were selected to undergo MBH reaction with 1 to give their respective adducts in very good yield with a very high diastereoselectivity. A plausible mechanism based on the assumption of a Zimmerman-Traxler-type transition state was proposed to explain the excellent selectivity observed with adducts derived from 1. The synthetic application of these adducts were shown by their stereoselective reduction to corresponding threo isomers in very good yield. Graphical Abstract.

Full text of DOI:10.1016/j.tet.2004.09.086

Tetrahedron 60 (2004) 11399–11406
A substrate controlled, very highly diastereoselective
Morita–Baylis–Hillman reaction: a remote activation of the
diastereofacial selectivity in the synthesis of
C-3-branched deoxysugars*
*
Ram Sagar, Chandra Shekhar Pant, Rashmi Pathak and Arun K. Shaw
Division of Medicinal and Process Chemistry, Central Drug Research Institute (CDRI), Lucknow 226001, India
Received 7 July 2004; revised 1 September 2004; accepted 23 September 2004
Available online 13 October 2004
Abstract—The Morita–Baylis–Hillman (MBH) reaction of p-nitrobenzaldehyde with C (6) acyl protected enuloside 1 in the presence of
TiCl4/TBAI yielded highly diastereoenriched C-3-branched deoxysugar derivative or MBH adduct 10a in high yield, while reactions of
unprotected enuloside 2a and C (6) alkyl protected enulosides 2d–e with p-nitrobenzaldehyde under the same conditions afforded the adducts
20a and 20d–e, respectively, in low yield with moderate selectivity. Several representative aromatic and aliphatic aldehydes were selected to
undergo MBH reaction with 1 to give their respective adducts in very good yield with a very high diastereoselectivity. A plausible
mechanism based on the assumption of a Zimmerman–Traxler-type transition state was proposed to explain the excellent selectivity
observed with adducts derived from 1. The synthetic application of these adducts were shown by their stereoselective reduction to
corresponding threo isomers in very good yield.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
prompted us to develop a convenient strategy for the
synthesis of C-3-branched deoxysugars in preparative scale.
Deoxysugars with a branched carbon skeleton occur
abundantly in nature and have been found in many
antibiotics. The appendage at the branching carbon can be
various side chains besides methyl, formyl, hydroxymethyl,
1-hydroxyethyl, acetyl, 2-hydroxyacetyl, 1,3-dimethylpro-
pyl and other side chains.1,2 There are number of antibiotics
that contain C-branched sugars as the glycosidic com-
ponents3 and they have been characterized from various
natural products.4 In synthetic organic chemistry C-
branched sugars have been identified as useful chiral
synthons for the total synthesis of natural products.2b,3a
Their use has also been explored in the synthesis of non-
carbohydrate compounds5 and carbohydrate mimetics.3a,c
Some of the most useful methods for the synthesis of
C-branched sugars involving the formation of new C–C
bond at the branching point take the advantage of the
reactivity of carbonyl group of uloses.6–8 Thus, the literature
reports on C-branched sugars for their synthetic
importance6–9 as well as biological significance1,10
The branching of a carbon skeleton by construction of C–C
bonds is one of the most challenging tasks in the field of
synthetic organic chemistry.11–13 During the last few years
Morita–Baylis–Hillman (MBH) chemistry14,15 has been
recognized as one of the most versatile and more economi-
cally feasible C–C bond forming reactions to generate
multifunctionalized allylic alcohols generally called MBH or
BH adducts. These find various applications as chiral
building blocks in organic synthesis.16 Highly diastereo-
selective BH reactions have been extensively studied during
the past few years.17 The syntheses of biologically active
important molecules involving asymmetric MBH reactions
have also been reported.18 However, the application of the
asymmetric MBH reaction in carbohydrate chemistry is very
limited.19,20 Herein, we wish to describe an efficient strategy
for an almost completely diastereoselective synthesis of C-3
branched deoxysugars involving the protocols of the
asymmetric MBH reaction. To our knowledge, this present
study represents an unprecedented substrate controlled/
directed, highly diastereoselective MBH reaction, catalyzed
by TiCl4/TBAI in carbohydrate chemistry. The various
aromatic and aliphatic aldehydes as electrophiles, and sugar-
derived chiral-activated alkenes as one of the chiral sources
were selected for the present study.
* CDRI Communication No. 6494.
Keywords: Diastereoselective; Morita–Baylis–Hillman reaction; 2,3-
Dideoxy sugar derivatives.
* Corresponding author. Tel.: C91 522 2364145; fax: C91 522 2223405;
e-mail: akshaw55@yahoo.com
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.09.086

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R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
2. Results and discussion
aldehydes (Table 1). The reactions were performed at
K78 8C/K30 8C. The efficacy of the reactivity of the
reagents TiCl4/TBAI and TiCl4/Me2S with almost all the
aldehydes used in this study showed that TiCl4/TBAI was
the superior (Scheme 1).
The required alkene 1 was prepared from the readily
3,4,6,tri-O-acetyl-D-glucal by modification of literature
methods.21 First, we attempted this reaction in CH2Cl2
with three-components, p-nitrobenzaldehyde (pnb), sugar-
22
enone 1 and TiCl4 at 0 8C. The adduct was obtained in a
Therefore, herein we wish to highlight our synthetic strategy
developed for a very high diastereoselective synthesis of
C-3-branched deoxysugar derivatives by taking the advan-
tage of MBH chemistry performed in the presence of
TiCl4/TBAI at K78 8C/K30 8C and the plausible mech-
anism for this reaction. Both aromatic as well as aliphatic
aldehydes formed the products in good to very good yield
(Table 1) with almost complete diastereoselectivity. As
expected the benzaldehyde derived adduct was obtained in
low yield (Table 1, entry 8) in 92 h. The MBH reaction of 1
with less reactive aldehyde like p-methoxybenzaldehyde did
not work under this condition. Once the reaction conditions
had been established, its generality with unprotected
enuloside 2a was examined. The free 6-OH in the adduct
could be replaced by an amino group, an H atom or a carbon
appendage by adopting standard synthetic protocols. This
could form novel 2,3,6-trideoxy branched sugar derivatives
which exist in important antibiotics.30 Therefore, when a
mixture of enuloside 2a, pnb and TiCl4/TBAI was stirred at
K78 8C/K30 8C for 33 h, the expected product formed
was in 40% (Table 2, entry 1) with moderate
diastereoselectivity.
very low yield. After several trial experiments using various
combinations of substrate and TiCl4 at different tempera-
tures, it was found that stirring a mixture of 2 equiv
aldehyde and 1 equiv alkene with 1.5 equiv TiCl4 in CH2Cl2
at K78 8C yielded the product (45%) with moderate
diastereoselectivity after 10 h, beyond that no appreciable
change was noticed in the course of the reaction. However,
the yield of the product was increased by 6% when an
additive (TBAI or Me2S) was added. Several research
groups have reported the TiCl4 mediated MBH reaction in
the presence of additives like TBAI23,24 or Me2S.25–27
Recently, we reported that the TiCl4/Me2S mediated BH
reaction can be successfully conducted on carbohydrate
enals with methyl vinyl ketone, extending the chain of
acyclic deoxysugars, where the unsaturation in the enals did
not interfere with the electrophilicity of the aldehydic
carbon.28,29 After exploring the combination of TiCl4/TBAI
or TiCl4/Me2S in different ratios, it was found that 20 mol%
of additive with 1.5 equiv TiCl4 turned out to be an effective
combination at K78 8C. The loading of 20 mol% of either
of the two additives resulted the desired adduct from pnb in
almost same yield (51%) after 10 h. However, when the
temperature of the reaction was gradually increased to
K30 8C (K78 8C/K30 8C), remarkable change was
observed in the yield of the chromatographically pure
adducts (85% with TBAI and 62% with Me2S). Only one
Table 2. TiCl4/TBAI mediated MBH reaction of enuloside 2a–e
Entry
Time (h)
Product
dra
Yield (%)b
R0
20a
20b
20c
20d
20e
1
2
3
4
5
H
33
5
6
10
10
82/18
O99/1
O99/1
83/17
40
64
88
28
44
1
CH3CO
p-NBzc
TBDPS
TBDMS
isomer was isolated from each combination. The H NMR
and 13C NMR spectra of the crude reaction mixture
surprisingly showed a very high degree of diastereo-
selectivity (O99%). Encouraged by these results, we
opted for a representative selection of aromatic and aliphatic
66/34
a Determined by 1H NMR and 13C NMR of the crude material.
b Isolated yield of pure isomer after column chromatography on silica gel.
c p-NBzZp-nitrobenzoyl group.
Table 1. TiCl4/TBAI mediated MBH reaction of enuloside 1 with
aldehydes at K78 to K30 8C
The difference in the reactivity of the two enulosides 1 and
2a with p-nitrobenzaldehyde in our MBH reaction can be
argued on the basis of the mechanistic aspects of the
reaction, as well as the geometry of the proposed transition
states (Scheme 4). Both the active alkenes follow the same
multiple mechanistic pathways taking place successively. It
can be presumed that the reaction starts with nucleophilic
attack of iodide from the TBAI to enuloside (Michael
acceptor), with concomitant shifting of the 2,3-double bond
to 3,4. This generates the oxyanion from the C-4 carbonyl
which in turn attacks the carbonyl carbon of the titanium-
coordinated pivaloyl group. By virtue of this conjugative
Entry
RCHO
Time (h) Product
dra
Yield (%)b
10a
1
2
3
4
5
6
7
8
p-NO2PhCHO
p-FPhCHO
8
48
48
30
10
6
10
O99/1
O99/1
O99/1
O99/1
O99/1
O99/1
O99/1
O99/1
85
68
82
81
64
80
86
26
10b
10c
CH3(CH2)2CHO
CH3(CH2)8CHO
m-NO2PhCHO
o-NO2PhCHO
p-CF3PhCHO
PhCHO
10d
10e
10f
10g
10h
92
a Determined by 1H NMR and 13C NMR of the crude material.
b Isolated yield of pure isomer after column chromatography on silica gel.
Scheme 1.

R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
11401
effect the formation of an orthoester intermediate31 ‘A’
could therefore be predicted. This resembles a trans decalin
(pseudo) conformation that can activate the site of reaction
(C-3) of the enolate. The conjugate addition of iodide to the
unprotected enuloside 2a in the presence of the lewis acid
could generate an unfavorable intermediate ‘B’, where
conformation of one of the rings is in a twist-boat form that
brings steric crowding near the site of the reaction. This
mechanism can justify the low yield of adduct and its
moderate selectivity from enuloside 2a. The reaction of 2a
with pnb in presence of TiCl4/Me2S did not form any
adduct.
In order to justify the above mechanistic argument, the
MBH reactions between other acyl (acetate and benzoyl,
2b–c) and alkyl protected tert-butyldiphenyllsilyl and
tert-butyldimethylsilyl (TBDPS and TBDMS, 2d–e)
enulosides, and pnb in the presence of TiCl4/TBAI at
K78 8C/K30 8C were carried out. The acetyl and
p-nitrobenzoyl protected enulosides furnished the
respective adducts in good to very good yield with same
selectivity. The alkyl protected enulosides (2d–e) formed
their respective adducts in low to moderate yield with
moderate selectivity (Scheme 2) (Table 2).
Scheme 4.
stereochemical model TS-I revealed that one of the
enantiotopic faces of the aldehyde, playing a key role in
the diastereoface selectivity, was well disposed to C-3 of the
enuloside, resulting in its intermolecular diastereoselective
re-face attack at the electrophilic carbonyl carbon of the
approaching aldehyde.
In order to show the synthetic utility of these adducts, the
C-4 keto groups of 10a, 10d and 10f were subjected to
stereoselective reduction with NaBH4 in the presence of
CeCl3$7H2O (Scheme 3) to obtain their threo derivatives
30a, 30d and 30f in 78, 68 and 74%, respectively (Table 3).
A very high diastereoselective MBH chemistry described
herein may be explained on the basis of the assumption that
Zimmermann–Traxler-type transition-state32 TS-I, invol-
ving A and the titanium coordinated aldehyde, was formed.
Among the other possible chelated transition-states TS-II or
TS-III, the latter can be completely ruled out by considering
severe steric repulsion arising due to 1,3-diaxial type
interactions between the a-faced O-isopropyl group at
C-1, and the approaching aldehyde from the same face
during the reaction as depicted in Scheme 4. The transition-
state TS-II is also unfavorable due to steric repulsion
between the R-group of the approaching aldehyde, and the
hydrogen at C-3 of the enuloside, therefore, giving
preference to TS-I over TS-II. Thus, consideration of the
Table 3. Diastereoselective reduction of Baylis–Hillman adducts (10a, 10d
and 10f) with NaBH4 and CeCl3$7H2O
Entry
B–H adducts
Time (h) Product
dra
Yield (%)b
10a
10d
10f
30a
1
2
3
2
5
5
O99/1
O99/1
O99/1
78
68
74
30d
30f
a Determined by 1H NMR and 13C NMR of the crude material.
b Isolated yield of pure isomer after column chromatography on silica gel.
Scheme 2.
Scheme 3.

11402
R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
3. Conclusion
by standard methods. Aldehydes were purchased from
Aldrich and Fluka chemical co. Enones 1 and 2a–e were
synthesized in the lab. IR spectra were recorded on Perkin–
Elmer 881 and FTIR-8210 PC Shimadzu Spectro-
photometers. Optical rotations were determined on an
Autopol III polarimeter using a 1 dm cell at 28 8C in
methanol or chloroform as the solvent; concentrations
mentioned are in g/100 mL. Elemental analyses were carried
out on Carlo-Erba-1108 and Vario EL III instruments.
In summary, we have developed and disclosed herein a new
and convenient strategy for the almost complete diastereo-
selective synthesis of new multifunctionalized unsaturated
C-3-alkylated 2,3-dideoxy sugars1 or derivatives of pyran-
3-ones in a good to very good yield. This involves TiCl4/
TBAI-mediated asymmetric Morita–Baylis–Hillman reac-
tion performed at K78 8C/K30 8C involving a readily
available sugar-derived enuloside and various aldehydes.33
On the basis of the experimental results, it was postulated
that a plausible chelated transition-state TS-I played a key
role in the formation of a very high diastereoenriched MBH
adduct involving multiple mechanistic pathways. The
energetically favored orthoester intermediate A governed
the remote activation34 of reaction site C-3 of the enuloside,
resulting the most favorable approach for the incoming
titanium-coordinated aldehyde to be from re-face, making
the whole reaction a substrate controlled diastereoselective
MBH reaction.35 The low yield of adducts 2a0, 2d0, 2e0 from
enulosides 2a, 2d, 2e is attributed to an energetically
unfavored twist-boat intermediate B. The resulting
unprecedented C-3 branched deoxy sugar derivatives (or
pyran-3-ones) may be as useful as other versatile key
intermediates like Corey’s lactone, the Wieland–Miescher
ketone, and the Prelog–Djerassi lactone which will find
numerous applications as chiral building blocks for the
construction of medicinally important molecules. These
may exhibit activities9,36 such as anti-microbial anti-viral,
anti-fungal, anti-coccidial, anti-inflammatory, anti-cancer,
etc. through skeleton rearrangement and functional group
transformation/manipulation or structural diversification
(Fig. 1). Our efforts to make this synthetic strategy more
versatile to obtain novel highly functionalized MBH
adducts as chiral building blocks from other active sugar-
enones are underway.
4.2. Typical reaction procedure for the preparation of
MBH adducts
To a stirred solution of tetrabutylammonium iodide, TBAI,
(0.2 mmol) in dry CH2Cl2 (5 mL) at K78 8C was added
TiCl4 (1.5 mmol) dropwise. After stirring for two minutes, a
mixture containing, 1 (1 mmol) and p-nitrobenzaldehyde
(2 mmol) in dry CH2Cl2 (5 mL) was added. The reaction
mixture was slowly warmed to K30 8C and stirred for the
specified time depending on the enulosides and aldehydes
used. A saturated aqueous solution of sodium bicarbonate
was added, followed by filtration through a celite pad.
The organic layer from the filtrate was separated, and the
aqueous layer was again extracted with ethyl acetate. The
organic layers were then combined, washed with brine
solution, and dried over sodium sulfate. The crude product
obtained after evaporation of the solvent was chromato-
graphed to yield pure compounds.
4.2.1. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (4-
nitrophenyl) methyl]-2,30-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (1 a). Oil. Eluent for column
chromatography (20% ethyl acetate/hexane); [Found: C,
59.32; H, 6.72; N, 3.09. C21H27NO8 requires C, 59.85; H,
6.46; N, 3.32%]; Rf (25% ethyl acetate/hexane) 0.39;
[a]DZK1.33 (c 0.30, CH3OH); nmax (neat) 3483, 1724,
1684 cmK1; dH (300 MHz, 0 CDCl3) 8.22 (2H, d, J4 ,3
0
0
or
0
0
0
0
0
0
0
6 ,7 Z8.7 Hz, H-4 and H-6 ), 7.57 (2H, d, J3 ,4 or 7 ,6 Z
8.7 Hz, H-30 and H-70), 6.60 (1H, d, J2,1Z3.6 Hz, H-2), 5.68
(1H, d, J1 ,OHZ4.2 Hz, H-10), 5.40 (1H, d, J1,2Z3.6 Hz,
0
H-1), 4.67 (1H, dd, J5,6aZ2.4 Hz, J5,6bZ5.6 Hz, H-5), 4.52
(1H, dd, J6a,5Z2.4 Hz, J6a,6bZ11.9 Hz, H-6a), 4.40 (1H,
dd, J6b,5Z5.7 Hz, J6b,6aZ12.0 Hz, H-6b), 4.05 (1H, sept.,
0
JZ6.3 Hz, –OCH (CH3)2), 3.13 (1H, d, JOH,1 Z4.8 Hz,
–OH), 1.24 (3H, d, JZ6.0 Hz, –OCH(CH3)2), 1.19 (3H, d,
JZ6.0 Hz, –OCH(CH3)2),1.14 (9H, s, –OCOC(CH3)3); dC
(50 MHz, CDCl3) 194.9 (C-4), 178.5 (–OCOC(CH3)3),
148.0 (C-3 and C-50), 141.2 (C-2), 138.9 (C-20), 128.0 (C-40
and C-60), 124.1 (C-30 and C-70), 92.1 (C-1), 72.9 (C-5),
71.8 (–OCH(CH3)2), 70.6 (C-10), 63.0 (C-6), 39.1
(–OCOC(CH3)3), 27.4 (–OCH(CH3)2), 23.5, 22.1
(–OCH(CH3)2); m/z (FABMS) 422 [MCH]C, 362
[MKOCH(CH3)2]C, 260, 243, 232, 217, 154, 136.
Figure 1. Arrow shows the site for diversification.
4. Experimental
4.1. General
All the reactions were monitored by warming the CeSO4 (1%
in 1 M H2SO4) sprayed precoated silica gel TLC plates at
100 8C. NMR spectra were recorded on Bruker Avance DPX
200 FT, Bruker Robotics and Bruker DRX 300 Spectro-
4.2.2. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (4-
fluorophenyl) methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (10b). Oil. Eluent for column
chromatography (12% ethyl acetate/hexane); [Found: C,
63.50; H, 7.52. C21H27O6F requires C, 63.94; H, 6.89%]; Rf
(25% ethyl acetate/hexane) 0.45; [a]DZK8.48 (c 0.33,
CH3OH); nmax (neat) 3481, 1726, 1686 cmK1; dH
(200 MHz, CDCl3) 7.34–7.04 (4H, m, Ph H), 6.56 (1H, d,
meters at 200, 300 MHz (1H) and 50, 75 MHz (13C). For 13
C
NMR reference CDCl3 appeared at 77.4 ppm, unless
otherwise stated. Mass spectra were recorded on a JEOL
SX 102/DA 6000 mass spectrometer using argon/xenon
(6 kV, 100 mA) as the FAB gas. Organic solvents were dried
J2,1Z3.6 Hz, H-2), 5.57 (1H, s, H-10), 5.38 (1H, d, J1,2
Z

R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
11403
3.6 Hz, H-1), 4.66(1H, dd, J5,6aZ2.6 Hz, J5,6bZ5.6 Hz, H-5),
4.53 (1H, dd, J6a,5Z2.6 Hz, J6a,6bZ11.9 Hz, H-6a), 4.39
(1H, dd, J6b,5Z5.7 Hz, J6b,6aZ11.9 Hz, H-6b), 4.02 (1H,
sept., JZ6.2 Hz, –OCH(CH3)2), 3.00 (1H, br s, –OH), 1.24
(3H, d, JZ6.1 Hz, –OCH(CH3)2), 1.19 (3H, d, JZ6.3 Hz,
–OCH(CH3)2), 1.16 (9H, s, –OCOC(CH3)3); dC (50 MHz,
CDCl3) 195.2 (C-4), 178.5 (–OCOC(CH3)3), 160.4 (C-50),
140.6 (C-2), 139.6 (C-3), 136.4 (C-20), 129.0 (C-40 and
C-60), 128.9 (C-30 and C-700), 92.2 (C-1), 72.9 (C-5), 71.6
(–OCH(CH3)2), 70.9 (C-1 ), 63.1 (C-6), 39.1 (–OCOC
(CH3)3), 27.5 (–OCOC(CH3)3), 23.6, 22.1 (–OCH(CH3)2);
m/z (FAB MS) 394 [M]C, 376 [MKH2O]C, 335
[MKOCH(CH3)2]C.
6.46; N, 3.32%] Rf (25% ethyl acetate/hexane) 0.42;
[a]DZC4.95 (c 0.20, CHCl3); nmax (neat) 3483, 1728,
1689 cmK1; dH (200 MHz, CDCl3) 8.26 (1H, s, H-30), 8.14
0
0
0
0
0
(1H, d, J5 ,6 Z7.2 Hz, H-5 ), 7.73 (1H, d,0 J7 ,6 Z7.3 Hz,
H-70), 7.53 (1H, t, J6 ,5 or 7 Z7.8 Hz, H-6 ), 6.71 (1H, d,
J2,1Z3.5 Hz, H-2), 5.42 (1H, d, J1,2Z3.6 Hz, H-1), 5.68
(1H, s, H-10), 4.66 (1H, dd, J5,6aZ2.6 Hz, J5,6bZ5.4 Hz,
H-5), 4.50 (1H, dd, J6a,5Z2.4 Hz, J6a,6bZ11.8 Hz, H-6a),
4.37 (1H, dd, J6b,5Z5.6 Hz, J6b,6aZ11.9 Hz, H-6b), 4.06
(1H, sept., JZ6.2 Hz, –OCH(CH3)2), 1.24 (3H, d, JZ
6.2 Hz, –OCH(CH3)2), 1.20 (3H, d, JZ6.2 Hz, –OCH
(CH3)2), 1.13 (9H, s, (–OCOC(CH3)3); dC (50 MHz, CDCl3)
195.0 (C-4), 178.0 (–OCOC(CH3)3), 148.8 (C-3), 143.1
(C–40), 141.2 (C-2), 138.8 0(C-20), 133.1 (C-30), 129.8 (C-50),
123.3 (C-70), 122.1 (C-6 ), 92.0 (C-1), 72.9 (C-5), 71.8
(–OCH(CH3)2), 70.6 (C-10), 63.0 (C-6), 39.1 (–OCOC
(CH3)3), 27.4 (–OCOC(CH3)3), 23.5, 22.1 (–OCH(CH3)2);
m/z (FABMS) 421 [M]C, 404 [MKOH]C, 362 [MKOCH
(CH3)2]C, 278, 260, 243, 218, 154.
0
0
0
4.2.3. Isopropyl-6-O-trimethylacetyl-3-(1-hydroxybu-
tyl)-2,3-dideoxy-a-D-glycero-hex-2-enopyranoside-4-
ulose (10c). Oil. Eluent for column chromatography (12%
ethyl acetate/hexane); [Found: C, 62.79; H, 8.07. C18H30O6
requires C, 63.13; H, 8.83%]; Rf (30% ethyl acetate/hexane)
0.55; [a]DZC44 (c 0.20, CH3OH); nmax (neat) 3424, 1726,
1686 cmK1; dH (200 MHz, CDCl3) 6.73 (1H, d, J2,1
Z
4.2.6. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (2-
nitrophenyl) methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (10f). Oil. Eluent for column
chromatography (15% ethyl acetate/hexane); [Found: C,
59.70; H, 6.71; N, 3.71. C21H27NO8 requires C, 59.85; H,
6.46; N, 3.32%]; Rf (25% ethyl acetate/hexane) 0.40;
[a]DZK6.13 (c 0.23, CHCl3); nmax (neat) 3478, 1727,
1687 cmK1; dH (200 MHz, CDCl3) 7.97 (1H, d, JZ8.0 Hz,
H-400), 7.68 (2H, m, H-50 and H-60), 7.46 (1H, t, JZ7.3 Hz,
0
3.7 Hz, H-2), 5.39 (1H, d, J1,2Z3.7 Hz, H-1), 4.68 (1H, dd,
J5,6aZ2.6 Hz, J5,6bZ5.7 Hz, H-5), 4.54 (1H, dd, J6a,5
Z
2.6 Hz, J6a,6bZ11.9 Hz, H-6a), 4.41 (2H, dd, J6b,5Z5.7 Hz,
J6b,6aZ11.9 Hz, H-6b and H-10), 4.04 (1H, sept., JZ6.2 Hz,
–OCH(CH3)2), 1.66–1.33 (4H, m, C-20 and C-30), 1.26 (3H,
d, JZ6.2 Hz, –OCH(CH3)2), 1.21 (3H, d, JZ6.3 Hz,
–OCH(CH3)2), 1.18 (9H, s, –OCOC(CH3)3), 0.93 (3H, t,
JZ7.2 Hz, H-40); dC (50 MHz, CDCl3) 195.4 (C-4), 178.5
(–OCOC(CH3)3, 140.0 (C-2), 139.4 (C-3), 92.2 (C-1), 72.9
(C-5), 71.5 (–OCH(CH3)2), 69.7 (C-10), 63.2 (C-6), 39.2
(–OCOC(CH3)3), 38.3 (C-20), 27.5 (–OCOC(CH3)3), 23.6,
22.2 (–OCH(CH3)2), 19.3 (C-30), 14.2 (C-40); m/z (FABMS)
343 [MCH]C, 324 [MKH2O]C, 283 [MKOCH(CH3)2]C,
265, 223, 181.
H-7 ), 6.66 (1H, d, J2,1Z3.6 Hz, H-2), 6.17 (1H, d, J1 ,OH
Z
4.0 Hz, H-10), 5.39 (1H, d, J1,2Z3.6 Hz, H-1), 4.69 (1H, dd,
J5,6aZ2.4 Hz, J5,6bZ5.8 Hz, H-5), 4.52 (1H, dd, J6a,5
Z
2.4 Hz, J6a,6bZ11.9 Hz, H-6a), 4.36 (1H, dd, J6b,5Z5.8 Hz,
J6b,6aZ11.9 Hz, H-6b), 4.06 (1H, sept., JZ6.1 Hz,
0
–OCH(CH3)2), 3.41 (1H, d, JOH,1 Z4.9 Hz, OH), 1.25
(3H, d, JZ6.1 Hz, –OCH(CH3)2), 1.19 (3H, d, JZ6.1 Hz,
–OCH(CH3)2), 1.14 (9H, s, –OCOC(CH3)3); dC (50 MHz,
CDCl3) 194.4 (C-4), 178.4 (–OCOC(CH3)3), 148.6 (C-3),
141.2 (C-2), 138.0 (C-30), 136.0 (C-20), 133.9 (C-40), 129.2
(C-50 and C-60), 125.0 (C-70), 92.1 (C-1), 72.7 (C-5), 71.6
(–OCH(CH3)2), 66.4 (C-10), 63.0 (C-6), 39.1 (–OCOC
(CH3)3), 27.4 (–OCOC(CH3)3), 23.5, 22.1 (–OCH(CH3)2);
m/z (FABMS) 420 [MK1]C, 404 [MKOH]C, 362
[MKOCH(CH3)2]C, 278, 260, 218, 154.
4.2.4. Isopropyl-6-O-trimethylacetyl-3-(1-hydroxyde-
cyl)-2,3-dideoxy-a-D-glycero-hex-2-enopyranoside-4-
ulose (10d). Oil. Eluent for column chromatography (10%
ethyl acetate/hexane); [Found: C, 67.51; H, 9.24. C24H42O6
requires C, 67.57; H, 9.92%]; Rf (15% ethyl acetate/hexane)
0.33; [a]DZC32.5 (c 0.24, CH3OH); nmax (neat) 3449,
1726, 1687 cmK1; dH (200 MHz, CDCl3) 6.66 (1H, d, J2,1
Z
3.6 Hz, H-2), 5.32 (1H, d, J1,2Z3.6 Hz, H-1), 4.60 (1H, dd,
J5,6aZ2.6 Hz, J5,6bZ5.7 Hz, H-5), 4.48 (1H, dd, J6a,5
Z
2.6 Hz, J6a,6bZ11.9 Hz, H-6a), 4.33 (1H, dd, J6b,5Z5.7 Hz,
J6b,6aZ11.9 Hz, H-6b), 4.30 (1H, t, JZ3.1 Hz, H-10), 4.05
(1H, sept., JZ6.2 Hz, –OCH(CH3)2), 1.55 (2H, m, H-20),
1.16 (20H, m, –OCH(CH3)2 and H-30 to H-90), 1.11 (9H, s,
(–OCOC(CH3)3), 0.80 (3H, t, JZ6.6 Hz, H-100); dC
(50 MHz, CDCl3) 195.4 (C-4); 178.5 (–OCOC(CH3)3),
140.0 (C-2), 139.4 (C-3), 92.2 0 (C-1), 72.9 (C-5), 71.5
(–OCH(CH3)2), 70.0 (C-1 ), 63.2 (C-6), 39.2
(–OCOC(CH3)3), 36.2, 32.3, 30.1, 30.0, 29.8, 29.7 (C-20
to C-70), 27.5 (–OCOC(CH3)3), 26.2 (C-80), 23.6 (C-90),
23.0, 22.2 (–OCH(CH3)2), 14.5 (C-100); m/z (FABMS) 426
[M]C, 408 [MKH2O]C, 367 [MKOCH(CH3)2]C, 265.
4.2.7. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (4-tri-
fluoromethylphenyl) methyl]-2,3-dideoxy-a-D-glycero-
hex-2-enopyranoside-4-ulose (10g). Oil. Eluent for column
chromatography (14% ethyl acetate/hexane); [Found: C,
58.45; H, 5.93. C22H27F3O6$1/4H2O requires C, 58.85; H,
6.17%]; Rf (20% ethyl acetate/hexane) 0.40; [a]DZC3.87
(c 0.28, CHCl3); nmax (neat) 3467, 1728, 1690 cmK1; dH
0
0
0
0
0
(200 MHz, CDCl3) 7.62 (2H, d, J4 ,3 or 6 ,7 Z8.2 Hz, H-04
and H-60), 7.50 (2H, d, J3 ,4 or 7 ,6 Z8.2 Hz, H-3 and H-7 ),
0
0
0
0
0
6.59 (1H, d, J2,1Z3.7 Hz, H-2), 5.62 (1H, s, H-10), 5.39 (1H,
d, J1,2Z3.6 Hz, H-1), 4.66 (1H, dd, J5,6aZ2.6 Hz, J5,6b
Z
5.4 Hz, H-5), 4.51 (1H, dd, J6a,5Z2.6 Hz, J6a,6bZ11.9 Hz,
H-6a),), 4.40 (1H, dd, J6b,5Z5.4 Hz, J6b,6aZ11.9 Hz,
H-6b), 4.03 (1H, sept., JZ6.1 Hz, –OCH(CH3)2 1.24 (3H,
d, JZ6.1 Hz, –OCH(CH3)2), 1.19 (3H, d, JZ6.1 Hz, –OCH
(CH3)2), 1.13 (9H, s, –OCOC(CH3)3); dC (75 MHz, CDCl3)
194.6 (C-4); 177.9 (–OCOC(CH3)3), 144.1 (C-3), 140.4
(C-2), 138.6 (C-20 and C-50), 127.0 (CF3), 126.9 (C-40 and
4.2.5. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (3-
nitrophenyl) methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (10e). Oil. Eluent for column
chromatography (14% ethyl acetate/hexane); [Found: C,
59.57; H, 5.92; N, 3.25. C21H27NO8 requires C, 59.85; H,

11404
R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
C-60), 125.3 (C-30 and C-700), 91.5 (C-1), 72.3 (C-5), 71.2
(–OCH(CH3)2), 70.5 (C-1 ), 62.4 (C-6), 38.5 (–OCOC
(CH3)3), 26.8 (–OCOC(CH3)3), 23.0, 21.5 (–OCH(CH3)2);
m/z (FAB MS) 443 [MK1]C, 427 [MKOH]C, 385
[MKOCH(CH3)2]C, 368, 301, 283, 266, 240.
(3H, d, JZ6.1 Hz, –OCH(CH3)2), 1.19 (3H, d, JZ6.1 Hz,
–OCH(CH3)2); dC (50 MHz, CDCl3) 194.7 (C-4), 171.0
(–OCOCH3), 148.0 (C-3 and C-50), 141.1 (C-2), 138.9
(C-20), 128.0 (C-40 and C-60), 124.0 (C-30 and C-700), 92.4
(C-1), 72.5 (C-5), 72.2 (–OCH(CH3)2), 70.3 (C-1 ), 62.8
(C-6), 23.4, 22.3 (–OCH(CH3)2), 21.0 (COCH3); m/z
(FABMS) 380 [MC1]C, 362 [MKOH]C, 320 [MKOCH
(CH3)2]C, 307, 289, 260, 232, 154.
4.2.8. Isopropyl-6-O-trimethylacetyl-3-[hydroxy (phe-
nyl) methyl]-2,3-dideoxy-a-D-glycero-hex-2-enopyrano-
side-4-ulose (10h). Oil. Eluent for column chromatography
(12% ethyl acetate/hexane); [Found: C, 64.94; H, 7.19.
C21H28O6$1/2H2O requires C, 65.43; H, 7.58%]; Rf (20%
ethyl acetate/hexane) 0.49; [a]DZK10.0 (c 0.08, CHCl3);
nmax (neat) 3430, 1727, 1687 cmK1; dH (200 MHz, CDCl3)
7.38–7.33 (5H, m, PhH), 6.56 (1H, dd, J2,1Z3.7 Hz, and
4.2.11. Isopropyl-6-O-4-nitrobenzoyl-3-[hydroxy (4-
nitrophenyl) methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (20c). Amorphous solid. Eluent for
column chromatography (16% ethyl acetate/hexane);
[Found: C, 56.27; H, 4.98; N, 5.79. C23H22N2O10 requires
C, 56.79; H, 4.55; N, 5.75%]; Rf (25% ethyl acetate/hexane)
0.50; [a]DZK39.13 (c 0.05, CHCl3); nmax (neat) 3453,
1727, 1688 cmK1; dH NMR (300 MHz, CDCl3) 8.27 (2H, d,
0
J2,1 Z1.2 Hz, H-2), 5.38 (1H, d, J1,2Z3.6 Hz, H-1), 5.58
(1H, s, H-10), 4.66 (1H, dd, J5,6aZ2.6 Hz, J5,6bZ5.7 Hz,
H-5), 4.53 (1H, dd, J6a,5Z2.6 Hz, J6a,6bZ11.9 Hz, H-6a),
4.40 (1H, dd, J6b,5Z5.7 Hz, J6b,6aZ11.9 Hz, H-6b), 4.02
(1H, sept., JZ6.2 Hz, –OCH(CH3)2), 1.24 (3H, d, JZ
6.2 Hz, –OCH(CH3)2), 1.18 (3H, d, JZ6.2 Hz, –OCH
(CH3)2), 1.15 (9H, s, –OCOC(CH3)3); dC (50 MHz, CDCl3)
195.2 (C-4), 178.4 (–OCOC(CH3)3), 140.6 (C-2 and C-20),
139.7 (C0-3), 128.9 (C-30 and C-70), 128.4 (C-50), 127.2 (C-40
and C-6 ), 92.2 (C-1), 72.9 (C-5), 71.5 (C-10 and –OCH
(CH3)2), 63.1 (C-6), 39.1 (–OCOC(CH3)3), 27.4 (–OCOC
(CH3)3), 23.5, 22.1 (–OCH(CH3)2); m/z (FABMS) 375
[MK1]C, 359 [MKOH]C, 317 [MKOCH(CH3)2]C, 233,
215, 198, 173, 154.
00 00
00 00
00 00
0
0
J4 ,3
0
Z9.0 Hz, H-4 and H-6 ), 8.19 (2H, d, J4 ,3
or 6 ,7
or
0
0
0
00 00
00 00
or 7 ,6
6 ,7 Z9.0 Hz, H-4 and H-6 ), 8.13 (2H, d, J3 ,4
Z
9.0 Hz, H-300 and H-700), 7.59 (2H, d, J3 ,4 or 7 ,6 Z9.0 Hz,
H-30 and H-70), 6.68 (1H, d, J2,1Z3.7 Hz, H-2), 5.44 (1H, d,
J1,2Z3.9 Hz, H-1), 5.74 (1H, s, H-10), 4.83–4.78 (2H, m,
0
0
0
0
H-5 and H-6a), 4.73 (1H, dd, J6b,5Z5.7 Hz, J6b,6a
Z
12.0 Hz, H-6b), 4.02 (1H, sept., JZ6.3 Hz, –OCH(CH3)2),
1.24 (3H, d, JZ6.0 Hz, –OCH(CH3)2), 1.20 (3H, d, JZ
6.0 Hz, –OCH(CH3)2); dC (50 MHz, CDCl3) 194.4 (C-4)
164.6 (C-100), 151.00 (C-500), 148.0 (C-50), 147.800(C-3), 141.3
(C-2), 138.09 (C-2 ),0 135.4 (C-200), 131.1 (C-4 and C-600),
128.0 (C-4 andC-6 ), 124.1 (C-30 and C-70), 123.9 (C-300
and C-700), 92.5 (C-1), 72.5 (C-5), 72.4 (–OCH(CH3)2), 70.2
(C-10), 64.1 (C-6), 23.5, 22.3 (–OCH(CH3)2); m/z (FABMS)
487 [MC1]C, 469 [MKOH]C, 427 [MKOCH(CH3)2]C,
410, 392, 307, 289, 278, 154.
4.2.9. Isopropyl-6-hydroxy-3-[hydroxy (4-nitrophenyl)
methyl]-2,3-dideoxy-a-D-glycero-hex-2-enopyranoside-
4-ulose (20a). Oil. Eluent for column chromatography (30%
ethyl acetate/hexane); [Found: C, 54.29; H, 6.07; N, 3.87.
C16H19NO7$H2O requires C, 54.01; H, 5.95; N, 3.94%]; Rf
(50% ethyl acetate/hexane) 0.39; [a]DZK10.86 (c 0.09,
4.2.12. Isopropyl-6-O-trimethyldiphenylsilyl-3-[hydroxy
(4-nitrophenyl)methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (20d). Oil. Eluent for column
chromatography (10% ethyl acetate/hexane); [Found: C,
65.82; H, 6.26; N, 2.12. C32H37NO7Si$1/2H2O requires C,
65.73; H, 6.55; N, 2.39%]; Rf (20% ethyl acetate/hexane)
0.50; [a]DZC9.0 (c 0.20, CHCl3); nmax (neat) 3464,
CHCl3); nmax (neat) 3405, 1686 cmK1; dH 0 (200 MHz,
0
0
0
0
0
CDCl3) 8.21 (2H, d, J4 ,3 or 6 ,7 Z8.6 Hz, H-40 and H-6 ),
0
0
0
0
0
7.57 (2H, d, J3 ,4 or 7 ,6 Z8.7 Hz, H-3 and H-7 ), 6.63 (1H,
d, J2,1Z3.4 Hz, H-2), 5.71 (1H, s, H-10), 5.42 (1H, d, J1,2
Z
3.7 Hz, H-1), 4.46 (1H, t, JZ3.9 Hz, H-5), 4.13–3.96 (2H,
m, H-6a and OCH(CH3)2), 3.89 (1H, dd, J6b,5Z3.9 Hz,
J6b,6aZ11.9 Hz, H-6b), 1.23 (3H, d, JZ6.3 Hz, –OCH
(CH3)2), 1.19 (3H, d, JZ6.2 Hz, –OCH(CH3)2); dC
(50 MHz, CDCl3) 196.7 (C-4) 148.0 (C-3 and C-50), 141.3
(C-2), 139.3 (C-20), 128.0 (C-40 and C-60), 124.1 (C-30 and
C-70), 92.2 (C-1), 74.5 (C-5), 71.9 (–OCH(CH3)2), 70.0
(C-10), 62.0 (C-6), 23.5, 22.1 (–OCH(CH3)2); m/z (FABMS)
338 [MC1]C, 320 [MKOH]C, 307 [MK32]C, 278
[MKOCH (CH3)2]C, 218, 154, 136.
1688 cmK1; dH (0200 MHz, CDCl3) 8.17 (2H, d, J4 ,3
0
0
or
0
0
0
6 ,7 Z8.7 Hz, H-4 and H-6 ), 7.66–7.63 (4H, m, PhH), 7.56
(2H, d, J3 ,4 or 7 ,6 Z8.7 Hz, H-3 and H-7 ), 7.42–7.36 (6H,
m, PhH), 6.58 (1H, dd, J2,1Z3.6 Hz, J2,1 Z1.0 Hz, H-2),
0
0
0
0
0
0
0
5.62 (1H, s, H-10), 5.47 (1H, d, J1,2Z3.5 Hz, H-1), 4.50 (1H,
dd, J5,6aZ2.8 Hz, J5,6bZ4.6 Hz, H-5), 4.09–3.99 (3H, m,
H-6a, H-6b and OCH(CH3)2), 1.23 (3H, d, JZ6.3 Hz,
–OCH(CH3)2), 1.19 (3H, d, JZ6.3 Hz, –OCH(CH3)2), 0.98
(9H, s, –C(CH3)3); dC (50 MHz, CDCl3) 196.1 (C-4), 148.1
(C-50), 148.0 (C-3), 141.60(C-2), 139.3 (C-20), 136.0 (PhC),
133.0 (PhC), 0 130.1 (C-4 and C-60), 128.0 (PhC), 124.1
(C-30 and C-7 ), 92.1 (C-1), 76.1 (C-5), 71.6 (–OCH(CH3)2),
71.2 (C-10), 63.7 (C-6), 27.0 (–C(CH3)3), 23.6, 22.1
(–OCH(CH3)2), 19.6 (–C(CH3)3); m/z (FABMS) 574
[MK1]C, 558 [MKOH]C, 518 [MK(CH3)3C]C, 498,
458, 438, 365, 335, 307, 241.
4.2.10. Isopropyl-6-O-acetyl-3-[hydroxy (4-nitrophenyl)
methyl]-2,3-dideoxy-a-D-glycero-hex-2-enopyranoside-
4-ulose (20b). Oil. Eluent for column chromatography (18%
ethyl acetate/hexane); [Found: C, 57.01; H, 5.36; N, 3.83.
C18H21NO8 requires C, 56.98; H, 5.58; N, 3.69%]; Rf (30%
ethyl acetate/hexane) 0.39; [a]DZK7.93 (c 0.12, CHCl3).
nmax (neat) 3483, 1740, 1692 cmK1; d0H (200 MHz, CDCl3)
0
0
0
0
0
8.22 (2H, d, J4 ,3 or 6 ,7 Z8.7 Hz, H-4 and H-6 ) 7.58 (2H,
0
0
0
0
0
0
0
d, J3 ,4 or 7 ,6 Z8.7 Hz, H-3 and H-7 ), 5.69 (1H, s, H-1 ),
6.65 (1H, d, J2,1Z3.7 Hz, H-2), 5.42 (1H, d, J1,2Z3.6 Hz,
H-1), 4.65 (1H, t, J5,6a&6bZ4.5 Hz, H-5), 4.46 (2H, d,
J6a&6b, 5Z4.5 Hz, H-6), 4.02 (1H, sept., JZ6.1 Hz, –OCH
(CH3)2), 3.13 (1H, br s, –OH), 2.03 (3H, s, OCOCH3), 1.24
4.2.13. Isopropyl-6-O-trimethyldimethylsilyl-3-[hydroxy
(4-nitrophenyl)methyl]-2,3-dideoxy-a-D-glycero-hex-2-
enopyranoside-4-ulose (20e). Oil. Eluent for column
chromatography (12% ethyl acetate/hexane); [Found: C,
58.42; H, 7.26; N, 2.81. C22H33NO7Si requires C, 58.52; H,

R. Sagar et al. / Tetrahedron 60 (2004) 11399–11406
11405
7.36; N, 3.10%]; Rf (30% ethyl acetate/hexane) 0.30;
[a]DZC8.33 (c 0.24, CHCl3); nmax (neat) 3467, 1687 cmK1
4.2.16. Isopropyl-6-O-(trimethylacetyl)-3-[hydroxy (2-
nitrophenyl) methyl]-2,3-dideoxy-a-D-threo-hex-2-eno-
pyranoside (30f). Sticky oil. Eluent for column chromatog-
raphy (25% ethyl acetate/hexane); [Found: C, 59.70; H,
6.88; N, 2.90. C21H29NO8 requires C, 59.56; H, 6.90; N,
3.30%]; Rf (40% ethyl acetate/hexane) 0.49; [a]DZK38.89
;
0
0
0
0
0
dH (300 MHz, CDCl3) 8.20 (2H, d, J4 ,3 or 6 ,7 Z8.7 Hz, H-04
0
and H-60), 7.56 (2H, d, J3 ,4 or 7 ,6 Z8.4 Hz, H-3 and H-7 ),
6.57 (1H, d, J2,1Z3.6 Hz, H-2), 5.63 (1H, s, H-10), 5.45
(1H, d, J1,2Z3.6 Hz, H-1), 4.44 (1H, t, JZ3.6 Hz, H-5),
4.08–4.01 (3H, m, H-6a, H-6b and –OCH(CH3)2), 1.24
(3H, d, JZ6.0 Hz, –OCH(CH3)2), 1.19 (3H, d, JZ6.0 Hz,
–OCH(CH3)2), 0.84 (9H, s, –C(CH3)3), 0.03 (6H, s,
–Si(CH3)2); dC (50 MHz, CDCl3) 196.1 (C-4), 147.7 (C-3
and C-50), 141.1 (C-2), 138.6 (C-20), 127.5 (C-40 and C-60),
123.6 (C-30 and C-70), 91.7 (C-1), 75.7 (C-5), 71.2 (–OCH
(CH3)2), 70.6 (C-10), 62.5 (C-6), 25.7 (–C(CH3)3) 23.1, 21.7
(–OCH(CH3)2), 18.2 (–C(CH3)3), K5.46 (–Si(CH3)2; m/z
(FABMS) 452 [MC1]C, 434 [MKOH]C, 392 [MKOCH
(CH3)2]C, 334, 318, 289, 266.
0
0
0
0
(c 0.09, CHCl3); nmax (neat) 3428, 2925, 1721, 1349 cmK1
;
0
0
0
dH (200 MHz, CDCl3) 7.88 (1H, d, J4 ,5 Z7.5 Hz, H-4 ),
0
0
0
0
0
0
7.87 (1H, d, J7 ,6 Z7.3 Hz, H-7 ), 7.67 (1H, t, J6 ,7 or 5 Z
7.3 Hz, H-60), 7.45 (1H, t, J5 ,4 or 6 Z7.5 Hz, H-4 ), 6.03
0
0
0
0
(1H, brd, J1 ,OHZ5.8 Hz, H-10), 5.52 (1H, br s, H-2), 5.05
0
(1H, d, J1,2Z2.8 Hz, H-1), 4.43 (1H, dd, J6a,5Z4.7 Hz,
J6a,6bZ12.1 Hz, H-6a), 4.19 (1H, dd, J6b,5Z2.0 Hz, J6b,6a
Z
12.2 Hz, H-6b), 4.12 (1H, d, JZ7.1 Hz, H-4), 4.06–3.89
(2H, m, H-5 and –OCH(CH3)2), 1.24 (3H, d, JZ6.4 Hz,
–OCH(CH3)2), 1.20 (3H, d, JZ6.3 Hz, –OCH(CH3)2), 1.14
(9H, s, –OCOC(CH3)3); dC (50 MHz, CDCl3) 180.2
(–OCOC(CH3)3), 148.7 (C-3), 140.5 (C-30), 136.5 (C-20),
133.5 (C-40), 129.6 (C-60), 129.0 (C-50), 126.3 (C-2), 125.0
(C-70), 92.9 (C-1), 72.2 (C-5), 70.4 (C-10 and –OCH(CH3)2),
65.1 (C-4), 64.3 (C-6), 39.3 (–OCOC(CH3)3), 27.5
(–OCOC(CH3)3), 24.0, 22.1 (–OCH(CH3)2); m/z
(FABMS) 424 [MC1]C, 364 [MKOCH(CH3)2]C, 346
[MKH2O–OCH (CH3)2]C, 265, 244, 202.
4.2.14. Isopropyl-6-O-(trimethylacetyl)-3-[hydroxy (4-
nitrophenyl) methyl]-2,3-dideoxy-a-D-threo-hex-2-eno-
pyranoside (30a). Solid, mp 122–24 8C. Eluent for column
chromatography (30% ethyl acetate/hexane); [Found: C,
59.62; H, 6.41; N, 3.34. C21H29NO8 requires C, 59.56; H,
6.90; N, 3.30%]; Rf (40% ethyl acetate/hexane) 0.47;
[a]DZC36.84 (c 0.03, CHCl3); nmax (KBr) 3425, 3027,
2978, 1728 cmK1; dH0 (200 MHz, CDCl3) 8.19 (2H, d, J4 ,3
0
0
0
0
0
0
0
0
0
or 6 ,7 Z8.7 Hz, H-4 and H-6 ), 7.57 (2H, d, J3 ,4 or 7 ,6 Z
8.5 Hz, H-30 and H-70), 5.66 (1H, d, J2,1Z2.8 Hz, H-2), 5.44
Acknowledgements
(1H, d, J1 ,OHZ6.5 Hz, H-10) 5.12, (1H, d, J1,2Z2.8 Hz, H-
0
1), 4.39 (1H, dd, J6b,5Z4.9 Hz, J6b,6aZ12.2 Hz, H-6b), 4.27
(1H, d, JZ7.2 Hz, H-4), 4.17 (1H, dd, J6a,5Z2.1 Hz,
J6a,6bZ12.2 Hz, H-6a), 4.01 (1H, sept., JZ6.0 Hz, –OCH
(CH3)2), 3.87 (1H, m, H-5), 1.23 (3H, d, JZ6.1 Hz, –OCH
(CH3)2), 1.16 (3H, d, JZ6.1 Hz, –OCH(CH3)2), 1.11 (9H, s,
–OCOC(CH3)3); dC (50 MHz, CDCl3) 180.4 (–OCOC
(CH3)3), 149.4 (C-50), 147.7 (C-3), 141.6 (C-20), 127.3
(C-40 and C-60), 126.8 (C-2), 123.9 (C-30 and C-700), 93.0
(C-1), 76.4 (C-5), 70.7 (–OCH(CH3)2), 70.4 (C-1 ), 65.2
(C-4), 64.3 (C-6), 39.2 (–OCOC(CH3)3), 27.4 (–OCOC
(CH3)3), 24.0, 22.1 (–OCH(CH3)2); m/z (FABMS) 422
[MK1]C, 406 [MKOH]C, 364 [MKOCH(CH3)2]C, 346
[MK18–OCH(CH3)2]C, 262, 244, 154.
We are thankful to Sophisticated Analytical Instrument
Facility (SAIF) for providing spectral data and Mr. Anoop
Kishore Pandey for technical assistance.
References and notes
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