Stereoselective synthesis of C-phenyl D- and L-glycero heptopyranosides

Article abstract of DOI:10.1016/S0957-4166(03)00038-7

D- and L-glycero-C-Phenyl heptopyranosides 1, 2 and 3 are synthesized for the first time from (R)-glyceraldehyde and L-ascorbic acid derivatives. The main strategy involves intramolecular nucleophilic substitution and double bond functionalisation.

Full text of DOI:10.1016/S0957-4166(03)00038-7

TETRAHEDRON:
ASYMMETRY
Pergamon
Tetrahedron: Asymmetry 14 (2003) 419–427
Stereoselective synthesis of C-phenyl
D- and
L-glycero
heptopyranosidesꢀ
Palakodety Radha Krishna,* B. Lavanya and G. V. M. Sharma
D-206/B, Discovery Laboratory, Organic Chemistry Division-III, Indian Institute of Chemical Technology,
Hyderabad 500 007, India
Received 4 September 2002; accepted 6 January 2003
Abstract—D- and L-glycero-C-Phenyl heptopyranosides 1, 2 and 3 are synthesized for the first time from (R)-glyceraldehyde and
L
-ascorbic acid derivatives. The main strategy involves intramolecular nucleophilic substitution and double bond functionalisa-
tion. © 2003 Elsevier Science Ltd. All rights reserved.
1. Introduction
2. Results and discussion
C-Glycosides have been the subject of considerable
interest in carbohydrate, enzymatic and metabolic chem-
istry since C-aryl and 2-deoxy-C-aryl glycosides are
commonly encountered structural features in a variety of
natural products1 and are chiral building blocks for the
asymmetric synthesis of natural products. Because of the
strong CꢀC bond at the anomeric center C-aryl glycosides
are endowed with an ability to withstand enzymatic and
acid hydrolysis.2 Hence, the synthesis of C-aryl glycosides
has become a challenging subject to organic chemists and
several synthetic strategies have resulted.3–6 Similarly,
higher and rare monosaccharides are important structural
features of highly functionalised carbohydrates and find
applications as intermediates in natural product synthe-
sis.7 However, to date, there appears to be less attention
drawntowardsthesynthesisofC-arylglycosidesofhigher
and rare sugar homologues. In continuation of our studies
on the synthesis of C-alkyl,8,9 and aryl10 glycosides,
C-saccharides,11 spiro-C-saccharides,12 2-deoxy and rare
saccharides13 and pseudo saccharides,14 we describe
herein a simple and straightforward synthetic approach
towards the synthesis of C-aryl heptopyranosides 1, 2 and
3, starting from 1,2-O-isopropylidene-(R)-glyceralde-
2.1. Synthesis of 6-[2%,2%-dimethyl-(4%R)-1%,3%-dioxolan-
4%-yl]-3-methylcarbonyloxy-2-phenyl-(2R,3S,4S,6R)-
tetrahydro-2H-4-pyranyl acetate 1 from 1,2-O-
isopropylidine-(R)-glyceraldehyde
The envisaged synthesis of 1, as outlined in Scheme 1,
involves the construction of a carbon skeleton 4 with an
appropriately positioned leaving group and an internal
nucleophile, wherein the phenylsulphonyl group was
chosen to act as both a protecting group and a leaving
group for the base-induced ring closure. Compound 4 is
envisaged from acetylene 5, which in turn could be
formed from 6, the acetylenic group of which serves
both as a handle to extrapolate the carbon chain as well
as to introduce the cis double bond for further
functionalisation.
Accordingly, the known compound15 1,2-O-isopropyl-
idine-(R)-glyceraldehyde
7
on Grignard reaction
(Scheme 2) with propargyl bromide in the presence of
Zn dust and saturated ammonium chloride in THF
gave 6 (68%) with predominant formation of the anti
isomer.16
hyde and L-ascorbic acid.
ꢀ IICT Communication No. 020815.
* Corresponding author. Fax: 91-40-7160387, 7160757; e-mail: prkgenius@iict.ap.nic.in
0957-4166/03/$ - see front matter © 2003 Elsevier Science Ltd. All rights reserved.
PII: S0957-4166(03)00038-7

420
P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
Scheme 1.
Scheme 2.
on asymmetric dihydroxylation17 (AD Mix a,
CH3SO2NH2, aq. tert-BuOH) afforded a mixture of
diols 11 in 60% yield. Diol 11 was acetylated without
purification using Ac2O–pyridine to afford 1 in 73%
yield, which was unambiguously characterized from its
spectroscopic data. For instance, 1H NMR analysis of 1
amply indicated a cis ring junction, wherein H-2 and
H-6 resonated at l 4.4 and l 3.8, as double doublet and
multiplet, respectively.
Compound 6 thus prepared was treated with benzene
sulphonyl chloride in the presence of Et3N to afford 8
(75%), wherein the sulphonate ester not only acts as a
protective group but also serves as a good leaving
group. Reaction of 8 with n-BuLi and benzaldehyde in
THF at −78°C gave carbinol 5 in 70% yield as a
diastereomeric mixture. The thus prepared alkyne 5 was
subjected to hydrogenation with Lindlar’s catalyst (Pd/
BaSO4) at room temperature in ethyl acetate to furnish
4 in quantitative yield.
2.2. Synthesis of 6-[2%,2%-dimethyl-(4%S)-1%,3%-dioxolan-4%-
yl]-3-methoxy-2-phenyl-(2S,3S,4R,6R)-tetrahydro-2H-
4-pyranyl acetate 2 and 6-[2%,2%-dimethyl-(4%S)-1%,3%-
dioxolan-4%-yl]-4-methoxy-2-phenyl-(2S,3R,4S,6R)-
Attempted Sharpless asymmetric epoxidation of alcohol
4 with (+)-DIPT and Ti(OiPr)4 in the presence of
cumene hydroperoxide was found to be very sluggish
and 4 was recovered unchanged. Hence, it was planned
to effect an intramolecular nucleophilic substitution
reaction first to result in dihydropyrans, which could be
further functionalised. Accordingly, cyclisation of 4
with K2CO3 in methanol furnished dihydropyrans 10
(58%) as an inseparable diastereomeric mixture, which
tetrahydro-2H-3-pyranyl acetate 3 from L-ascorbic acid
The synthetic approach to the
heptopyranosides is outlined in Scheme 3, wherein the
epoxide 13 obtained from -ascorbic acid was envi-
sioned as a good starting material to realize 2. Thus, 2
L
-glycero-a-C-phenyl
L

P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
421
Scheme 3.
in 51% yield (Scheme 4). Alcohol 15 was protected as
the sulphonate ester 16 (PhSO2Cl–Et3N) which on fur-
ther reaction with DDQ in aq. CH2Cl2 (9:1) afforded 17
in 71% yield. Lindlar’s reaction of compound 17 in
ethyl acetate afforded cis olefin 18 (94%), which on
further oxidation using PCC in CH2Cl2 afforded alde-
hyde 12 in 83% yield. Aldehyde 12 was subjected to
could be made from 4a, which in turn could be
obtained on treatment of aldehyde 12 with aryl Grig-
nard, while 12 in turn could be obtained from
bic acid, through 13.
L-ascor-
Accordingly, the propargyl ether 14 was treated with
n-BuLi and epoxide 1318 in THF at −78°C to afford 15
Scheme 4.

422
P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
Table 1. Spectroscopic data for compound 2
Proton
l (ppm)
Multiplicity
NOE
H-2
H-3
H-4
H-5(a)
H-5(b)
H-6
H-4%
H-5%b
H-5%a
4.22
4.11
5.30
2.01
1.79
3.99
3.87
3.87
4.06
d (J2,3=2.2 Hz)
dd (J3,2=2.2 Hz, J3,4=4.6 Hz)
dt (J4,5=6.0 Hz, J4,3=4.6 Hz)
ddd (J5a,6=2.2 Hz, J5a,5b=13.7 Hz, J5a,4=5.6 Hz)
ddd (J5b,6=9.7, J5a,5b=13.7, J4,5b=5.6 Hz)
ddd (J6,4%=6.0, J6,5a=2.6, J6,5b=9.7 Hz)
m
m
m
With OMe, H-5(b)
With H-5(b)
With H-5(a), Ph, acetate CH3
With H-6
With H-2
With H-5(a)
With acetonide CH3
No NOE
No NOE
Table 2. Spectroscopic data for compound 3
Proton
l (ppm)
Multiplicity
NOE
H-2
H-3
H-4
H-5(a)
H-5(b)
H-6
H-4%
H-5%b
H-5%a
4.20
5.25
4.05
2.01
1.78
3.99
3.87
3.87
4.05
d (J2,3=4.6 Hz)
dd (J3,2=4.6 Hz, J3,4=6.8 Hz)
m
m
ddd (J5b,6=9.7 Hz, J5a,5b=13.7 Hz, Jb,4=5.6 Hz)
ddd (J6,4%=6.0 Hz, J6,5a=2.6 Hz, J6,5b=9.7 Hz)
m
m
m
With H-5(b)
With H-5(a)
With H-5(b)
With H-6, H-3
With H-2, H-4
With H-5(a)
No NOE
No NOE
No NOE
Grignard reaction with phenylmagnesium bromide in
THF to afford a diastereomeric mixture of alcohols 4a
in 86% yield. Kinetic resolution of 4a under Sharpless
asymmetric epoxidation conditions using (+)-DIPT,
Ti(iOPr)4 and cumene hydroperoxide afforded an insep-
arable mixture of alcohols, i.e. epoxy alcohol 19 and
allylic alcohol 4b. Subsequent reaction of the mixture of
19 and 4b with K2CO3 in refluxing methanol afforded
three chromatographically separable products 20 (34%),
21 (12%) and 22 (22%). Regioisomers 20 and 21 were
reasoned to have been derived from the epoxy alcohol
19 by cyclisation.
4.22 as a doublet (J=2.2 Hz) and H-4 at l 5.30 as
doublet by triplet (J=4.6, 6.0 Hz), while the H NMR
1
of compound 3 revealed H-2 at l 4.20 as doublet
(J=4.6 Hz) and H-4 as multiplet at l 4.05 respectively
supporting the predicted structure. The structures of
these two compounds 2 and 3 were further established
from the detailed spectral analysis (Fig. 1) using the
vicinal couplings (J) as well as the data from the
NOESY experiments (Table 1).
On reaction with Ac2O in pyridine at room tempera-
ture, the C-aryl glycosides 20 and 21, were indepen-
dently converted into the corresponding acetates 2 and
3 in quantitative yields, respectively (Scheme 5).
The structures of 2 and 3 were unambiguously deter-
1
mined based on their spectroscopic data. The H NMR
spectrum of compound 2 revealed H-2 resonance at l
Figure 1.
Scheme 5.

P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
423
The six-membered pyran ring in 2 adopts the boat
conformation (Fig. 1). The assigned structure is sup-
ported by NOESY cross peaks between H2-OCH3,
H2–H5(b) and H6–H5(a). It was also observed that
there was no NOE between H2–H4 and H2–H6, indi-
cating that both the substituents at C-2 and C-6 are
trans to each other.
27 mmol) and Et3N (3.5 g, 35.3 mmol) in CH2Cl2 (40
mL) containing DMAP (catalytic) at 0°C was stirred
for 5 h. It was treated with saturated aq. NaHCO3
solution (10 mL) for 30 min, diluted with CH2Cl2 (50
mL) and the organic layer was separated. Organic layer
was washed with water (10 mL), brine (10 mL) and
dried (Na2SO4). Evaporation of solvent and purifica-
tion of residue by column chromatography (silica gel,
60–120 mesh, EtOAc:hexane, 1:9) afforded 2,2-di-
methyl-4-[1%-phenylsulfonyloxy-(1%S)-3%-butynyl]-(4R)-
1,3-dioxolane 8 as a semi-solid (5.5 g, 75% yield). [h]D25
1
In the H NMR spectrum of compound 3 the observed
resonance for H-2 at l 4.22 as doublet and H-4 at l
4.05 as multiplet, respectively, supported the predicted
structure. For compound 3 the six-membered pyran
ring is in the boat conformation (Fig. 1). NOESY
experiments have shown the cross peaks between H2–
H5(b), H4–H5(b), H3–H5(a) and H5(a)–H6, thus con-
firming the assigned structure (Table 2).
1
+9.4 (c 1.2, CHCl3); H NMR (200 MHz, CDCl3): l
8.0–7.9 (d, 2H, J=4.7 Hz, Ar-H), 7.6 (m, 3H, Ar-H),
4.5 (q, 1H, J=4.7 Hz, H-1%), 4.24 (q, 1H, J=4.7 Hz,
H-4), 4.0 (dd, 1H, J=4.7, 5.7 Hz, H-5a), 3.82 (dd, 1H,
J=4.7, 2.3 Hz, H-5b), 2.6 (br.s, 2H, H-2%), 1.9 (br.s,
1H, H-4%), 1.4–1.2 (br.s, 6H, -CH3); IR (neat): 1360,
3320 cm−1; EIMS (m/z): 310 (M+), 311 (M++1). Anal.
calcd for C15H18O5S: C, 58.05; H, 5.85; S, 10.33; found:
C, 58.18; H, 5.60; S, 10.0%.
3. Conclusion
The present protocol describes a simple and flexible
approach for the synthesis of C-aryl heptopyranosides
with rare stereochemistries, which are otherwise inac-
cessible from natural sources. Thus, the present strategy
adopted resulted in the first synthesis of new C-aryl
heptopyrasnosides 1, 2 and 3.
4.1.3. 4-[5%-Hydroxy-5%-phenyl-(5%R/S)-1%-phenylsulfonyl-
oxy-(1%S)-3%-pentynyl]-2,2-dimethyl-(4R)-1,3-dioxolane,
5. To a stirred solution of compound 8 (1.5 g, 4.8
mmol) in dry THF (10 mL) at −78°C was added
n-BuLi (0.5 mL, 7.2 mmol; 1.5N hexane solution)
dropwise. After 30 min a solution of freshly distilled
benzaldehyde (0.62 g, 5.8 mmol) in THF (5 mL) was
added and the mixture stirred at the same temperature
for further 2 h. The reaction mixture was allowed to
attain room temperature, diluted with sat. aq. NH4Cl
solution (30 mL) and extracted with ethyl acetate (2×30
mL). Organic layer was washed with brine (5 mL),
dried (Na2SO4), evaporated and the residue purified by
column chromatography (silica gel, 60–120 mesh,
EtOAc:hexane, 3:10) to afford 4-[5%-hydroxy-5%-phenyl-
(5%R/S)-1%-phenylsulfonyloxy-(1%S)-3%-pentynyl]-2,2-di-
methyl-(4R)-1,3-dioxolane 5 as a colorless syrup (1.4 g,
4. Experimental
4.1. Synthesis of 6-[2%,2%-dimethyl-(4%R)-1%,3%-dioxolan-4-
yl]-3-methylcarbonyloxy-2-phenyl-(2R,3S,4S,6R)-
tetrahydro-2H-4-pyranyl acetate, 1
4.1.1. 1-[2%,2%-Dimethyl-(4%R)-1%,3%-dioxolan-4%-yl]-(1S)-3-
butyn-1-ol, 6. To a cooled (0°C) and stirred mixture of
7 (5.0 g, 38.4 mmol), Zn dust (4.99 g, 76.9 mmol) and
propargyl bromide (9.1 g, 76.9 mmol) in THF (60 mL)
was added a saturated aq. solution of NH4Cl (15 mL)
dropwise over a period of 30 min and the mixture was
stirred for 12 h at ambient temperature. It was filtered
and the precipitate was thoroughly washed with chloro-
form (3×25 mL). The aqueous layer was separated and
treated with 5% cold HCl (10 mL) to dissolve the
suspended turbid material. The clear solution was
extracted with CHCl3 (2×20 mL) and the combined
organic layers were washed successively with 10% aq.
NaHCO3 (30 mL), brine (25 mL), dried (NaSO4) and
concentrated to furnish crude alcohol, which was
purified by flash chromatography (silica gel, 60–120
mesh, EtOAc:hexane, 1:9) to afford 1-[2%,2%-dimethyl-
(4%R)-1%,3%-dioxolan-4%-yl]-(1S)-3-butyn-1-ol 6 as a thick
1
70%). [h]2D5 +17.0 (c 0.9, CHCl3); H NMR (200 MHz,
CDCl3): l 7.90–7.80 (m, 2H, Ar-H), 7.6–7.4 (m, 5H,
Ar-H), 7.3–7.2 (m, 3H, Ar-H), 5.3 (br.s, 1H, H-5%), 4.6
(q, 1H, J=5.2 Hz, H-1%), 4.2–3.9 (m, 2H, H-4, 5a),
3.8–3.6 (dd, 1H, J=5.2, 2.6 Hz, H-5b), 2.55 (br.d, 2H,
J=2.6 Hz, H-2%), 1.3–1.2 (br.s, 6H, -CH3); IR (neat):
1360, 2140 cm−1; FABMS (m/z): 416 (M+), 330, 275.
Anal. calcd for C22H24O6S: C, 63.45; H, 5.81; S, 7.70;
found: C, 63.48; H, 5.2; S, 7.0%.
4.1.4.
4-[5%-Hydroxy-5%-phenyl-1%-phenylsulfonyloxy-
(1%S,5%R/S,3%Z)-3%pentenyl]-2,2-dimethyl-4(R)-1,3-dioxo-
lane, 4. A solution of compound 5 (1.2 g, 2.8 mmol) in
ethyl acetate (50 mL) was treated with Lindlar’s cata-
lyst (cat.) in the presence of quinoline (two drops) and
subjected to hydrogenation for 4 h. The reaction mix-
ture was filtered, solvent evaporated and residue
purified by column chromatography (silica gel, 60–120
mesh, EtOAc:hexane, 3:10) to afford 4-[5%-hydroxy-5%-
phenyl-1%-phenylsulfonyloxy-(1%S,5%R/S,3%Z)-3%pentenyl]-
2,2-dimethyl-4(R)-1,3-dioxolane 4 as a colorless liquid
1
syrup (4.42 g, 68%). [h]D +3.8 (c 1.0, CHCl3); H NMR
(200 MHz, CDCl3): l 4.20–3.90 (m, 3H, H-5%, 4%),
3.75–3.65 (m, 1H, H-1), 2.50 (m, 2H, H-2), 2.00 (m, 1H,
H-4), 1.40, 1.39 (2s, 6H, -CH3); IR (neat): 3320 cm−1;
EIMS (m/z): 170 (M+). Anal. calcd for C9H14O3: C,
63.51; H, 8.29; found: C, 63.58; H, 8.0%.
4.1.2.
2,2-Dimethyl-4-[1%-phenylsulfonyloxy-(1%S)-3%-
1
(1.1 g, 91%). [h]2D5 +17.7 (c 1.1, CHCl3); H NMR (200
butynyl]-(4R)-1,3-dioxolane, 8. A solution of compound
6 (4.0 g, 23.5 mmol), benzene sulphonyl chloride (4.8 g,
MHz, CDCl3): l 7.95 (d, 2H, J=2.9 Hz, Ar-H), 7.50

424
P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
(m, 5H, Ar-H), 7.20 (m, 3H, Ar-H), 5.8–5.70 (dd, 1H,
J=1.17 Hz, H-4%), 5.70–5.6 (m, 1H, H-3%), 5.10 (m, 1H,
H-5%), 4.70–4.60 (m, 1H, H-1%), 4.2 (m, 1H, H-4), 3.9
(m, 1H, H-5a), 3.8 (m, 1H, H-5b), 2.50–2.42 (m, 1H,
H-2%a), 2.40–2.38 (m, 1H, H-2%b), 1.38–1.22 (s, 6H,
-CH3); 13C NMR (50 MHz, CDCl3): l 171.60, 129.84,
128.98 (3C), 128.20 (2C), 127.03, 77.64, 72.50 (3C),
70.91 (2C), 31.28, 25.41, 22.15 (3C), 22.08 (3C); IR
(neat): 728, 1360 cm−1; FABMS (m/z): 418 (M+), 332,
277. Anal. calcd for C22H26O6S: C, 63.14; H, 6.26; S,
7.66; found: C, 63.18; H, 6.32; S, 7.56%.
dimethyl-(4%R)-1%,3%-dioxolan-4%-yl]-3-methylcarbonyl-
oxy-2-phenyl (2R,3S,4S,6R)-tetrahydro-2H-4-pyranyl
acetate 1 as a syrup (0.088 g, 70%). [h]2D5 +7.5 (c 0.8,
1
CHCl3); H NMR (200 MHz, CDCl3): l 7.4–7.2 (m,
5H, Ar-H), 5.9 (d, 1H, J=9.6 Hz, H-4), 4.9 (q, 1H,
J=3.84 Hz, H-3), 4.4 (dd, 1H, J=6.2, 3.84 Hz, H-2),
4.2 (m, 2H, H-4%, 5%a), 3.8 (m, 1H, H-6), 3.64 (m, 1H,
H-5%b), 2.1 (s, 3H, OAc), 2.0 (s, 3H, OAc), 1.79 (m, 1H,
H-5a), 1.6 (m, 1H, H-5b), 1.40, 1.35 (br.s, 6H, CH3);
FABMS (m/z): 378 (M+), 319, 260. Anal. calcd for
C20H26O7: C, 63.48; H, 6.92; found: C, 63.54; H, 7.0%.
4.1.5. (2R)-2-[2%,2%-Dimethyl-(4%R)-1%,3%-dioxolan-4%-yl)-
6-(R/S)-6-phenyl-3,6-dihydro-2H-pyran, 10. A solution
of compound 4 (0.5 g, 1.2 mmol) in methanol (10 mL)
was treated with K2CO3 (0.16 g, 1.2 mmol) and heated
under reflux for 4 h. Methanol was evaporated and the
residue extracted with ethyl acetate (50 mL). The
organic layer was washed with water (5 mL), brine (5
mL), dried (Na2SO4), concentrated and the residue
purified by column chromatography (silica gel, 60–120
mesh, EtOAc:hexane, 3:20) to afford 10 as a syrup
4.2. Synthesis of 6-[2%,2%-dimethyl-(4%S)-1%,3%-dioxolan-4%-
yl] - 3 - methoxy - 2 - phenyl - (2S,3S,4R,6R) - tetrahydro-
2H-4-pyranyl acetate, 2 and 6-[2%,2%-dimethyl-(4%S)-1%,3%-
dioxolan - 4% - yl] - 4 - methoxy - 2 - phenyl - (2S,3R,4S,6R)-
tetrahydro-2H-3-pyranyl acetate, 3
4.2.1.
1-[2%,2%-Dimethyl-(4%S)-1%,3%-dioxolan-4%-yl]-5-(4-
stirred
methoxybenzyloxy)-(1S)-3-pentyn-1-ol, 15.
A
1
(0.18 g, 58%). [h]2D5 +7.5 (c 0.8, CHCl3); H NMR (200
solution of 1-(4-methoxybenzyloxy) propyne 14 (3.6 g,
20.4 mmol) in dry THF (30 mL) at −78°C under a
nitrogen atmosphere was sequentially treated with n-
BuLi (15 mL, 216 mmol, 1.6N hexane solution),
BF3Et2O (2.95 mL, 20.7 mmol), followed by the addi-
tion 2,2-dimethyl-4-[(2S)-oxiran-2yl]-(4S)-1,3-dioxalane
13 (2.3 g, 15.9 mmol) in THF (20 mL) at an interval of
10 min. After 6 h the reaction mixture was treated with
a sat. NaHCO3 solution (15 mL) at −78°C followed by
the addition of saturated aqueous NH4Cl solution (10
mL) and stirred for 30 min. The reaction mixture was
diluted with ethyl acetate (100 mL) and washed with sat
NaHCO3 (15 mL). Combined organic extracts were
washed successively with saturated NH4Cl (50 mL),
brine (50 mL) and dried (Na2SO4). Evaporation of
solvent under reduced pressure and purification of
residue by column chromatography (silica gel 60–120
mesh, EtOAc:hexane, 3:17) gave 1-[2%,2%-dimethyl-(4%S)-
1%,3%-dioxolan-4%-yl]-5-(4-methoxybenzyloxy)-(1S)-3-pen-
tyn-1-ol, 15 as a yellow syrup (3.3 g, 51%). [h]2D5: −1.8 (c
MHz, CDCl3): l 7.4–7.2 (m, 5H, Ar-H), 6.1 (t, 1H,
J=5.26 Hz, H-4), 5.7 (dd, 1H, J=15.7, 5.26 Hz, H-5),
5.6 (m, 2H, H-6), 4.5 (m, 1H, H-2), 4.0 (m, 2H, H-5%),
3.6 (dt, 1H, J=5.26, 1.32 Hz, H-4%), 1.8–1.9 (br.s, 2H,
H-4), 1.35 (br.s, 6H, CH3); FABMS (m/z): 260 (M+).
Anal. calcd for C16H20O3: C, 73.82; H, 7.74; found: C,
73.85; H, 8.0%.
4.1.6. 6 - [2%,2% - Dimethyl - (4%R) - 1%,3% - dioxolan - 4% - yl]-
3 - methylcarbonyloxy - 2 - phenyl - (2R,3S,4S,6R) - tetra-
hydro-2H-4-pyranyl acetate, 1. A solution of AD Mix a
(0.54 g, 0.69 mmol) in water:tert-BuOH (5 mL, 1:2) was
treated with CH3SO2NH2 (0.065 g, 0.69 mmol) and
cooled to 0°C. A solution of dihydropyran 10 (0.18 g,
0.69 mmol) in tert-BuOH (2 mL) was added to the
reaction mixture all at once and the heterogeneous
slurry stirred for 24 h. Solid Na2SO4 (10 mg) was added
and the reaction mixture allowed to warm to room
temperature. After 30 min the reaction mixture was
extracted with ethyl acetate (3×10 mL), washed with
brine (2×10 mL) and dried (Na2SO4). The organic layer
was evaporated under reduced pressure and the residue
purified by column chromatography (silica gel, 60–120
mesh, ethyl acetate:pet. ether, 1:2) to afford 11 as a
thick syrup (0.36 g, 60%) as an inseparable mixture.
[h]2D5 +7.5 (c 0.8, CHCl3).
1
1.0, CHCl3); H NMR (200 MHz, CDCl3): l 7.5 (d,
2H, J=7.5 Hz, Ar-H), 6.85 (d, 2H, J=7.5 Hz, Ar-H),
4.50 (.s, 2H, -OCH2), 4.2–4.0 (m, 5H, H-4%, 5, 5%),
3.8–3.6 (m, 1H, H-1), 3.6 (s, 3H, -OCH3), 2.5–2.4 (m,
2H, H-2), 1.5–1.4 (br.s, 3H, -CH3), 1.4–1.3 (br.s, 3H,
-CH3); FABMS (m/z): 320 (M+). Anal. calcd for
C18H24O5: C, 67.5; H, 7.5; found: C, 67.6; H, 7.7%.
A solution of the above crude diol 11 (0.1 g, 0.34
mmol) in pyridine (0.50 mL) containing DMAP (cata-
lytic) was treated with Ac2O (0.068 mL, 0.68 mmol) at
0°C and stirred for 1 h at room temperature. The
reaction mixture was diluted with a saturated aq.
NaHCO3 solution (15 mL) and extracted with CH2Cl2
(2×10 mL). The combined organic layers were washed
with a saturated aq. CuSO4 solution (10 mL), water (10
mL), brine (15 mL) and dried (Na2SO4). The solvent
was evaporated under reduced pressure and the residue
was purified by column chromatography (silica gel,
60–120 mesh, EtOAc:hexane, 1:4) to afford 6-[2%,2%-
4.2.2. 4-[5%-(4-Methoxybenzyloxy)-1%-phenylsulfonyloxy-
(1%S)-3%-pentynyl]-2,2-dimethyl-(4S)-1,3-dioxolane,
16.
To a solution of 15 (1.4 g, 4.3 mmol) in CH2Cl2 (20
mL) Et3N (0.66 mL, 6.5 mmol) was added and cooled
to 0°C. After 5 min benzenesulphonyl chloride (1.15
mL, 6.5 mmol), was added the reaction mixture was
stirred at room temperature for 6 h. The reaction
mixture was diluted with water (20 mL) and extracted
with CH2Cl2 (3×50 mL). The combined organic extracts
were washed with brine (20 mL), dried (Na2SO4) and
concentrated in vacuum to a syrup, which was purified

P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
425
by column chromatography (silica gel, EtOAc:hexane,
3:22) to afford 4-[5%-(4-methoxybenzyloxy)-1%-phenylsul-
fonyloxy - (1%S) - 3% - pentynyl] - 2,2 - dimethyl - (4S) - 1,3-
dioxolane, 16 as a syrup (1.6 g, 80%). [h]2D5: −0.55 (c 1.8,
mL), decanted and washed repeatedly with ether. The
combined ethereal layers were filtered over a bed of
Celite to afford crude 4-[4%-formyl-1%-phenylsulfonyl-
oxy-(1%S,3%Z)-3%-butenyl]-2,2-dimethyl-(4S)-1,3-dioxo-
lane, 12 (0.41 g, 83%), which was used in the next
reaction without purification.
1
CHCl3); H NMR (200 MHz, CDCl3): l 7.95 (d, 2H,
J=6.9 Hz, Ar-H), 7.7 (m, 3H, Ar-H), 7.25 (d, 2H,
J=7.5 Hz, Ar-H), 6.85 (d, 2H, J=7.5 Hz, Ar-H), 4.55
(q, 1H, J=5.1 Hz, H-1%), 4.50 (s, 2H, -OCH2), 4.25–
4.02 (m, 3H, H-4, 5), 4.02–3.92 (m, 2H, H-5%), 3.80 (s,
3H, -OCH3), 2.80 (dd, 1H, J=15.3 Hz, H-2%a), 2.60
(dd, 1H, J=6.1 Hz, H-2%b), 1.3–1.2 (br.s, 6H, CH3);
FABMS (m/z): 460 (M+), 323, 319. Anal. calcd for
C24H28O7S: C, 62.5; H, 6.1; S, 6.9; found: C, 62.6; H,
6.0; S, 6.8%.
To a freshly prepared solution of phenyl magnesium
bromide [prepared from bromobenzene (0.56 g, 3.5
mmol) and magnesium (0.085 g, 3.5 mmol) in THF (10
mL)], aldehyde 12 (0.40 g, 1.2 mmol) in THF (20 mL)
was added dropwise at 0°C and stirred at room temper-
ature for 3 h. The reaction mixture was quenched with
a sat. aq. NH4Cl (5 mL) solution and extracted with
ethyl acetate (3×25 mL). The organic layer was washed
with water (10 mL), brine (10 mL), dried (Na2SO4) and
evaporated. The crude product was purified by column
chromatography (silica gel 60–120 mesh, EtOAc:
hexane, 1:4) to afford 4-[5%-hydroxy-5%-phenyl-1%-
phenylsulfonyloxy - (1%S,5%R/S,3%Z) - 3%pentenyl] - 2,2-
dimethyl-(4S)-1,3-dioxolane, 4a, as a syrup (0.42 g,
4.2.3. 4-[5%-Hydroxy-1%-phenylsulfonyloxy-(1%S)-3%-pen-
tynyl]-2,2-dimethyl-(4S)-1,3-dioxolane, 17. DDQ (0.59
g, 2.62 mmol) was added to a stirred solution of 16 (1.2
g, 2.6 mmol) in aq. CH2Cl2 (15 mL; 1:9) and stirred at
room temperature for 2 h. The reaction mixture was
diluted with water (10 mL) and extracted with CH2Cl2
(3×10 mL), organic layer was dried (Na2SO4), evapo-
rated under reduced pressure and purified the residue
by column chromatography (silica gel 60–120 mesh,
EtOAc:hexane, 3:22) to afford 4-[5%-hydroxy-1%-phenyl-
sulfonyloxy-(1%S)-3%-pentynyl]-2,2-dimethyl-(4S)-1,3-
dioxolane, 17 as a syrup (0.63 g, 71%). [h]2D5: −1.0 (c 1.1,
1
86%). [h]2D5: −14.8 (c 0.8, CHCl3); H NMR (200 MHz,
CDCl3): l 7.9 (d, 2H, J=1.3 Hz, Ar-H), 7.6 (m, 5H,
Ar-H), 7.3 (m, 3H, Ar-H), 5.8–5.7 (dd, 1H, J=1.3, 2.6
Hz, H-4%), 5.65 (m, 1H, H-3%), 5.1 (t, 1H, J=1.3 Hz,
H-5%), 4.6 (m, 1H, H-1%), 4.2 (m, 1H, H-4), 3.9 (m, 1H,
H-5a), 3.8 (m, 1H, H-5b), 2.5 (m, 1H, H-2%a), 2.39 (m,
1H, H-2%b), 1.28–1.22 (s, 6H, CH3); EIMS (m/z): 418
(M+), 332, 277. Anal. calcd for C22H26O6S: C, 63.1; H,
6.2; S, 7.6; found: C, 63.0; H, 6.3; S, 7.8%.
1
CHCl3); H NMR (200 MHz, CDCl3): l 7.9 (d, 2H,
J=5Hz, Ar-H), 7.7 (m, 1H, Ar-H), 7.6 (m, 2H, Ar-H),
4.6 (m, 1H, H-1%), 4.4 (m, 1H, H-5a), 4.2 (m, 2H, H-5b,
4), 4.0 (m, 1H, H-5%a), 3.8 (m, 1H, H-5%b), 2.8 (dd, 1H,
J=10.0, 5.0 Hz, H-2%a), 2.58 (dd, 1H, J=5.0, 10.0 Hz,
H-2%b), 1.3–1.2 (br.s, 6H, CH3); EIMS (m/z): 341 (M++
1), 340 (M+). Anal. calcd for C16H20O6S: C, 56.4; H,
5.9; S, 9.4; found: C, 56.5; H, 6.0; S, 9.3%.
4.2.6. Sharpless kinetic resolution of 4a to give 19 and
4b. Anhydrous CH2Cl2 (2 mL) was cooled to −20°C
under N2, Ti(iOPr)4 (0.29 mL, 1.06 mmol) and (+)-
DIPT (0.29 mL, 1.12 mmol) were sequentially added
and stirred for 5–10 min. A solution of alcohol 4a (0.4
g, 0.95 mmol) in CH2Cl2 (5 mL) followed by cummene
hydroperoxide (0.16 mL, 0.5 mmol) was added to the
reaction mixture. The resulting mixture was stored at
−10°C for 2 days. The cold reaction mixture was
allowed to warm to 0°C and quenched with 10% aq.
NaOH solution saturated with NaCl (8 mL) stirred
vigorously for 1 h. The reaction mixture was filtered
through Celite and extracted with ethyl acetate (2×25
mL). The organic layer was washed with brine (10 mL),
dried (Na2SO4) evaporated under reduced pressure and
purified by column chromatography (silica gel 60–120
mesh, EtOAc:hexane, 1:4) to afford a mixture of 4-
[2%(3¦ - hydroxy - (3¦S) - (phenyl)methyl - (1%R,2%R) - 2%-
(oxiranyl] - 1§ - phenylsulfonyloxy - (1§S) - ethyl) - 2,2-
dimethyl-(4S)-1,3-dioxolane 19 and 4-[5%-hydroxy-5%-
phenyl-1%-phenylsulfonyloxy-(1%S,3%Z)-3%-pentenyl]-2,2-
dimethyl-(4S)-1,3-dioxolane 4b as a syrup (0.42 g,
4.2.4. 4-[5%-Hydroxy-1%-phenylsulfonyloxy-(1%S,3%Z)-3%-
pentenyl]-2,2-dimethyl-(4S)-1,3-dioxolane, 18. To a solu-
tion of 17 (0.60 g, 1.76 mmol) in ethyl acetate (10 mL),
quinoline (0.01 mL) and Lindlar catalyst (0.01 g) were
added and stirred at room temperature under hydrogen
atmosphere for 6 h. Work up of the reaction mixture as
described for 4 purification by column chromatography
(silica gel, EtOAc:hexane, 3:22) furnished 4-[5%-
hydroxy-1%-phenylsulfonyloxy-(1%S,3%Z)-3%-pentenyl]-2,
2-dimethyl-(4S)-1,3-dioxolane, 18 as a syrup (0.56 g,
1
94%). [h]2D5: −1.7 (c 1.8, CHCl3); H NMR (200 MHz,
CDCl3): l 8.0–7.9 (d, 2H, J=5.5 Hz, Ar-H), 7.7–7.5
(m, 3H, Ar-H), 5.82–5.75 (m, 1H, H-4%), 5.45–5.28 (m,
1H, H-3%), 4.62–4.45 (m, 1H, H-1%), 4.25–3.84 (m, 4H,
H-5%a, H-4, H-5), 3.82–3.78 (m, 1H, H-5%b), 2.65–2.28
(m, 2H, H-2%), 1.25–1.20 (br.s, 6H, CH3); FABMS
(m/z): 342 (M+), 332, 277. Anal. calcd for C16H22O6S:
C, 56.1; H, 6.4; S, 9.3; found: C, 56.2; H, 6.2; S, 9.4%.
1
86%). [h]2D5: −2.7 (c 0.5, CHCl3); H NMR (200 MHz,
CDCl3): l 7.9 (br.t, 2H, J=1.3 Hz, Ar-H), 7.6 (m, 3H,
Ar-H), 7.3 (br.s, 5H, Ar-H), 5.75 (dd, 0.5H, J=1.3, 2.6
Hz, H-3%), 5.65 (m, 0.5H, H-4%), 5.1 (t, 1H, J=1.3 Hz,
H-5%), 4.6 (m, 1H, H-1%), 4.2 (m, 1H, H-4), 3.9 (m, 1H,
H-5a), 3.8 (m, 1H, H-5b), 3.12–2.93 (m, 1H, epoxy
protons), 2.5 (m, 1H, H-2%a), 2.39 (m, 1H, H-2%b),
1.28–1.22 (s, 6H, CH3).
4.2.5.
4-[5%-Hydroxy-5%-phenyl-1%-phenylsulfonyloxy-
(1%S,5%R/S,3%Z)-3%pentenyl]-2,2-dimethyl-(4S)-1,3-dioxo-
lane, 4a. To a stirred suspension of pyridinium
chlorochromate (PCC; 0.47 g, 2.21 mmol) in CH2Cl2 (5
mL), a solution of alcohol 18 (0.50 g, 1.46 mmol) in
CH2Cl2 (5 mL) was added and the mixture was stirred
for 1 h. The reaction mixture was diluted with ether (45

426
P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
4.2.7. Cyclisation of the mixture 19 and 4b. A solution
of the mixture of 19+4b (0.5 g, 1.2 mmol) in methanol
(10 mL) was treated with K2CO3 (0.16 g, 1.2 mmol) and
heated under reflux for 4 h. Work up of the reaction as
reported for 10 gave the residue, which was purified by
column chromatography (silica gel, 100–200 mesh,
EtOAc:hexane, 3:20). First eluted was 2-[2%,2%-dimethyl-
(4%S)-1%,3%-dioxolan-4%-yl]-6-phenyl-(2R,6S)-3,6-dihydro-
2H-pyran 22 as a syrup (0.033 g, 22%). [h]2D5 −17.8 (c
4.2.9.
6-[2%,2%-Dimethyl-(4%S)-1%,3%-dioxolan-4%-yl]-4-
methoxy - 2 - phenyl - (2S,3R,4S,6R) - tetrahydro - 2H - 3-
pyranyl acetate, 3. A solution of 22 (0.10 g, 0.32 mmol)
in pyridine (0.5 mL) containing DMAP (catalytic) was
treated with Ac2O (0.03 mL, 0.32 mmol) at 0°C and
stirred for 1 h at room temperature. Work up of the
reaction as described for 1 and purification by column
chromatography (silica gel, 100–200 mesh, EtOAc:
hexane, 1:4) gave 6-[2%,2%-dimethyl-(4%S)-1%,3%-dioxolan-
4%-yl]-4-methoxy-2-phenyl-(2S,3R,4S,6R)-tetrahydro-
2H-3-pyranyl acetate, 3 as a syrup (0.10 g, 92%). [h]D25
1
0.8, CHCl3); H NMR (200 MHz, CDCl3): l 7.4–7.2
(m, 5H, Ar-H), 5.8–5.9 (dt, 1H, J=2.6 Hz, H-4),
5.7–5.6 (dd, 1H, J=5.2, 2.6 Hz, H-5), 5.2 (m, 1H, H-6),
4.5 (m, 1H, H-2), 4.1 (m, 2H, H-5%), 3.59 (dt, 1H,
J=5.2 Hz, H-4%), 1.9 (m, 2H, H-3), 1.4–1.35 (br.s, 6H,
CH3). EIMS (m/z): 260 (M+). Anal. calcd for C16H20O3:
C, 73.8; H, 7.7; found: C, 73.6; H, 7.8%.
1
−6.4 (c 0.5, CHCl3); H NMR (400 MHz, CDCl3): l
7.4–7.2 (m, 5H, Ar-H), 5.25 (dd, 1H, J3,2=4.6, J3,4=6.8
Hz, H-3), 4.2 (d, 1H, J2,3=4.6 Hz, H-2), 4.05 (m, 2H,
H-4,5%a), 3.99 (ddd, 1H, J6,4%=6.0, J6,5a=2.6, J6,5b=9.7
Hz, H-6), 3.87 (m, 2H, H-4%,5%b), 3.25 (s, 3H, OCH3),
2.01 (m, 1H, H-5a), 1.98 (s, 3H, OAc), 1.78 (ddd, 1H,
Second eluted was 6-[2%,2%-dimethyl-(4%S)-1%,3%-dioxolan-
4%-yl]-3-methoxy-2-phenyl-(2S,3S,4R,6R)-tetrahydro-
2H-4-pyranol, 20 as a syrup (0.06 g, 34%). [h]2D5 −18.7
J5b,6=9.7, J5a,5b=13.7, J5b,4=5.6 Hz, H-5b), 1.4, 1.38
(2s, 6H, CH3). FABMS (m/z): 350 (M+).
1
(c 1.2, CHCl3); H NMR (200 MHz, CDCl3): l 7.4–7.2
(m, 5H, Ar-H), 4.3 (m, 1H, H-4), 4.1 (d, 1H, J=3.1 Hz,
H-2), 3.95 (m, 2H, H-3,5%a), 3.85 (dt, 1H, J=4.7 Hz,
H-6), 3.75 (m, 2H, H-4%,5%b), 3.25 (s, 3H, OCH3), 2.1
(m, 2H, H-5), 1.38, 1.36 (2s, 6H, CH3). Anal. calcd for
C17H25O5: C, 66.0; H, 8.1; found: C, 66.1; H, 8.0%.
Acknowledgements
B. Lavanya acknowledges the financial support in the
form of a fellowship from the CSIR, New Delhi, India.
Thirdelutedwas6-[2%,2%-dimethyl-(4%S)-1%,3%-dioxolan-4%-
yl] - 4 - methoxy - 2 - phenyl - (2S,3R,4S,6R) - tetrahydro-
2H-3-pyranol 21 as a syrup (0.021 g, 12%). [h]2D5 +2.66
References
1
(c 1.2, CHCl3); H NMR (200 MHz, CDCl3): l 7.4–7.2
1. (a) Anthracycline Antibiotics; E. I. Khadem, H. S., Ed.;
Academic Press: New York, 1992; (b) Lee, M. D.;
Dunne, T. S.; Chang, C. C.; Ellestad, G. A.; Siegel, M.
M.; Morton, G. O.; McGahren, W. J.; Borders, D. B. J.
Am. Chem. Soc. 1987, 109, 3466–3468; (c) Roush, W. R.;
Lin, X.-F. J. Org. Chem. 1991, 56, 5740–5742.
(m, 5H, Ar-H), 4.3 (m, 1H, H-4), 4.2 (dd, 1H, J=4.4,
6.6 Hz, H-3), 4.1 (d, 1H, J=4.4 Hz, H-2), 4.0 (m, 1H,
H-6), 3.9 (m, 2H, H-4%, 5%a), 3.6 (dd, 1H, J=4.4, 2.2
Hz, H-5%b), 3.25 (s, 3H, OCH3), 2.2 (ddd, 1H, J=6.7,
4.4, 2.2 Hz, H-5a), 1.8 (m, 1H, H-5b), 1.3, 1.2 (2s, 6H,
CH3).
2. Du, Y.; Linhardt, R. J.; Vlahov, I. R. Tetrahedron 1998,
54, 9913–9959.
4.2.8.
6-[2%,2%-Dimethyl-(4%S)-1%,3%-dioxolan-4%-yl]-3-
3. (a) Hadfield, A. F.; Sartoslli, A. F. Carbohydr. Res. 1982,
701, 197–208; (b) Ciment, D. M.; Ferrier, R. J. J. Chem.
Soc. 1980, 441–445; (c) Grynkiewicz, G.; Priebe, W.;
Zamojski, A. Carbohydr. Res. 1979, 68, 33–41.
4. (a) Hocksell, A.; Daves, G. D. J. Prog. Med. Chem. 1985,
22, 1–65; (b) Franz, G.; Gruen, M. Plasta 1983, 47,
131–140.
5. (a) Toshima, K.; Matsuo, G.; Nakata, M. J. Chem. Soc.,
Chem. Commun. 1994, 199–200; (b) Allev, P.; Anastasia,
M.; Ciuffreda, P.; Fiecchi, A.; Scala, A.; Bingham, S.;
Muir, M.; Tyman, J. J. Chem. Soc., Chem. Commun.
1991, 1319–1320; (c) Parker, K. A.; Coburn, C. A. J. Am.
Chem. Soc. 1991, 113, 8516–8518; (d) Daves, G. D. J.
Acc. Chem. Res. 1990, 23, 201–206; (e) Bellosta, V.;
Czernecki, S. J. Chem. Soc., Chem. Commun. 1989, 199–
200; (f) Czeonecki, S.; Vilee, G. J. Org. Chem. 1989, 54,
610–612; (g) Casiraghi, G.; Cornia, M.; Colombo, L.;
Rassu, G.; Favo, G. G.; Bericch, M. F.; Zetta, L. Tetra-
hedron Lett. 1988, 29, 5549–5552; (h) Schmidt, R. R.;
Frick, W.; Haag-Zieno, B.; Apaarao, S. Tetrahedron Lett.
1987, 28, 4045–4048; (i) Bellosta, V.; Czernecki, S. Carbo-
hydr. Res. 1987, 171, 279–288.
methoxy - 2 - phenyl - (2S,3S,4R,6R) - tetrahydro - 2H - 4-
pyranyl acetate, 2. A solution of 20 (0.1 g, 0.32 mmol)
in pyridine (0.5 mL) containing DMAP (catalytic) was
treated with Ac2O (0.03 mL, 0.32 mmol) at 0°C and
stirred for 1 h at room temperature. The reaction
mixture was worked up as described for 1 and purified
by column chromatography (silica gel, 100–200 mesh,
EtOAc:hexane, 1:4) to afford 6-[2%,2%-dimethyl-(4%S)-
1%,3%-dioxolan-4%-yl]-3-methoxy-2-phenyl-(2S,3S,4R,6R)-
tetrahydro-2H-4-pyranyl acetate, 2 as a thick syrup
1
(0.10 g, 92%). [h]2D5 −20.5 (c 1.0, CHCl3); H NMR (400
MHz, CDCl3): l 7.4–7.2 (m, 5H, Ar-H), 5.3 (dt, 1H,
J4,3=4.6, J4,5=6.0 Hz, H-4), 4.22 (d, 1H, J2,3=2.2 Hz,
H-2), 4.11 (dd, 1H, J3,2=2.2, J3,4=4.6 Hz, H-3), 4.06
(m, 1H, H-5%a), 3.99 (ddd, 1H, J6,4%=6.0, J6,5a=2.6,
J
6,5b=9.7 Hz, H-6), 3.87 (m, 2H, H-4%,5%b), 3.25 (s, 3H,
OCH3), 2.01 (ddd, 1H, J5a,6=2.2, J5a,5b=13.7, J5a,4
5.6 Hz, H-5a), 1.98 (s, 3H, OAc), 1.79 (ddd, 1H,
=
J
5b,6=9.7, J5a,5b=13.7, J5b,4=5.6 Hz, H-5b), 1.38, 1.34
(2s, 6H, CH3). 13C NMR (50 Hz, CDCl3): l 21.26,
25.46, 28.68, 29.77, 35.86, 57.34, 67.59, 75.51, 76.83,
79.87, 84.01, 87.54, 127.71, 128.32. FABMS (m/z): 350
(M+). Anal. calcd for C19H26O6: C, 65.13; H, 7.48;
found: C, 65.11; H, 7.44%.
6. (a) Kometani, T.; Konda, H.; Fujimori, Y. Synthesis
1988, 1005–1007; (b) Matsumoto, T.; Katsuki, M.;
Suzuki, K. Tetrahedron Lett. 1988, 29, 6935–6938; (c)

P. Radha Krishna et al. / Tetrahedron: Asymmetry 14 (2003) 419–427
427
Mastumoto, T.; Katsuki, M.; Juna, H.; Suzuki, K. Tetra-
hedron Lett. 1989, 30, 6185–6188; (d) Mastumoto, T.;
Hosoga, T.; Suzuki, K. Tetrahedron Lett. 1990, 31, 4629–
4632; (e) Matsumoto, T.; Hosoya, T.; Suzuki, K. Synlett
1991, 709–711.
M.; Reddy, V. G.; Radha Krishna, P. Tetrahedron 2002,
58, 3801–3812.
13. Sharma, G. V. M.; Subhas Chander, A.; Radha Krishna,
P. Tetrahedron: Asymmetry 2001, 12, 539–544.
14. (a) Sharma, G. V. M.; Subhas Chander, A.; Radha
Krishna, P.; Krishnudu, K.; Rao, M. H. V. R.; Kunwar,
A. C. Tetrahedron: Asymmetry 2000, 11, 2643–2646; (b)
Sharma, G. V. M.; Rajendra Prasad, T.; Radha Krishna,
P.; Krishnudu, K.; Rao, M. H. V. R.; Kunwar, A. C.
Tetrahedron: Asymmetry 2000, 11, 4499–4507.
15. Schmid, C. R.; Bryant, J. D. Org. Synth. 1995, 72, 6–12.
16. (a) Chattopadhyay, A. J. Org. Chem. 1996, 61, 6104–
6107; (b) Petrier, C.; Luche, J. L. J. Org. Chem. 1985, 50,
910–911; (c) Anh, N. T. Top. Curr. Chem. 1980, 88,
145–170; (d) Lubineau, A.; Auge, J.; Queneau, Y. Syn-
thesis 1994, 741–760.
7. Scott, J. W. In Asymmetric Synthesis; Morrison, J. D.;
Scott, J. W., Eds.; Academic Press: New York, 1984; Vol.
4, pp. 1–209.
8. Sharma, G. V. M.; Subhas Chander, A.; Krishnudu, K.;
Radha Krishna, P. Tetrahedron Lett. 1997, 38, 9051–
9054.
9. Sharma, G. V. M.; Subhas Chander, A.; Krishnudu, K.;
Radha Krishna, P. Tetrahedron Lett. 1998, 39, 6957–
6960.
10. (a) Radha Krishna, P.; Lavanya, B.; Ilangovan, A.;
Sharma, G. V. M. Tetrahedron: Asymmetry 2000, 11,
4463–4472; (b) Sharma, G. V. M.; Raman Kumar, K.;
Sreenivas, P.; Radha Krishna, P.; Chorghade, M. S.
Tetrahedron: Asymmetry 2002, 13, 687–690.
17. Sharpless, K. B.; Amberg, W.; Bernni, L. H.; Crispino,
A. G.; Hartung, J.; Jeong, K.-S.; Kwong, H.-L.;
Morikawa, K.; Wang, Z.-M.; Xu, D.; Zhang, X.-L. J.
Org. Chem. 1992, 57, 2768–2771.
11. Sharma, G. V. M.; Hymavati, L.; Radha Krishna, P.
18. Abushanab, E.; Vemishetti, P.; Leiby, R. W.; Singh, H.
K.; Mikkilineni, A. B.; Wu, D. C.-J.; Saibaba, R.; Panz-
ica, R. P. J. Org. Chem. 1988, 53, 2598–2602.
Tetrahedron Lett. 1997, 38, 6929–6932.
12. (a) Sharma, G. V. M.; Reddy, V. G.; Radha Krishna, P.
Tetrahedron Lett. 1999, 40, 1783–1786; (b) Sharma, G. V.