Synthesis of analogues of calicheamicin and neocarzinostatin chromophore

Article abstract of DOI:10.1016/j.tet.2004.03.021

The work presents a synthetic route to the CD ring of calicheamicin and in the case of neocarzinostatin an approach to a functionalised cyclopentane-1,3-diol containing the naturally occurring naphthoate and a glucosamine motif. In the case of the NCS derivative some biological activity (cytotoxicity) was observed.

Full text of DOI:10.1016/j.tet.2004.03.021

Tetrahedron 60 (2004) 4019–4029
Synthesis of analogues of calicheamicin and
neocarzinostatin chromophore
*
Alessandra Cirla, Angela R. McHale and John Mann
School of Chemistry, Queen’s University Belfast, Belfast BT9 5AG, UK
Received 3 December 2003; revised 6 February 2004; accepted 4 March 2004
Abstract—The work presents a synthetic route to the CD ring of calicheamicin and in the case of neocarzinostatin an approach to a
functionalised cyclopentane-1,3-diol containing the naturally occurring naphthoate and a glucosamine motif. In the case of the NCS
derivative some biological activity (cytotoxicity) was observed.
q 2004 Elsevier Ltd. All rights reserved.
1. Introduction
of the glycosyl unit has not been established. This natural
product has also been the target of numerous synthetic
studies9 and one successful synthesis by Myers.10 We have
prepared a core structure that includes a homochiral
polysubstituted cyclopentane with sugar and naphthoate
units attached, in order to explore the essential features
required for selective DNA duplex binding.
Calicheamicin gI1 1 from the soil microorganism Micro-
monospora echinospora has been the subject of numerous
synthetic and biological studies.1 Much of its biological
activity can be ascribed to th0e way in which it binds
specifically to 50-TCCT and 5 -ACCT sequences in the
minor groove of DNA,2 and a limited number of analogues
have also been prepared with a view to establish structure
activity relationships. In particular, both Nicolaou3 and
Danishefsky4 have prepared glycones with modifications to
the A, B and E rings. Moutel and Prandi have prepared AB
rings with acyclic E ring analogues, and a DCB analogue
where an ester oxygen replaces the thioester linkage.5 But
there has been no investigation of the effects of changing the
D-ring. We have devised some novel and flexible chemistry
for the production of a range of CD-analogues.
Neocarzinostatin 2 from Streptomyces carzinostaticus was
in fact the first member of the family of enediynes to be
isolated,6 and also has a range of biological activities
including anti-proliferative activity.7 Its central naphthoate
is known to bind duplex DNA intercalatively,8 but the role
Keywords: Neocarzinostatin; Calicheamicin; Cyclopentane-1,3-diol.
*
Corresponding author. Tel.: þ44-2890-975525; fax: þ44-2890-382117; e-mail address: j.mann@qub.ac.uk
0040–4020/$ - see front matter q 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.tet.2004.03.021

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A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
2. Results and discussion
optimisation, this approach allows access to novel CD-ring
analogues of calicheamicin which possess (in principle) a
range of substituents at C-2, 3 and 4 of the rhamnose
ring. Despite the efforts of Nicolaou,3 Danishefski,4 and
Prandi,5 this possibility has not been available before our
work.
Our key intermediate for the production of the CD ring
system of calicheamicin was 1-thiophenyl-a-L-rhamno-
pyranoside 3 prepared from L-rhamnose via the sequence
shown in Scheme 1 (overall yield for the three steps 35%).
Our initial target in the neocarzinostatin series was the
aminoglucoside of hydroxycyclopentyl naphthoate 15 in
order to assess its biological activity.
The ultimate intention was the preparation of a library of
core structures which carry conventional cytotoxic drugs
and various carbohydrate moieties, and an investigation of
the effects of these substituents on the intercalative binding
of the naphthoate unit to duplex DNA. The naphthoic acid
component 16 was prepared essentially according to the
route described by Myers13 (Scheme 3), though the initial
Heck reaction was improved markedly through the use of
DMF as co-solvent (time of reaction reduced from 12 to
2 h).
Scheme 1.
Compound 3 was then converted into the bis-acetal 4 using
Ley’s technology11 (butan-2,3-dione in MeOH containing
camphor sulphonic acid, 58%), and thence into the 2-methyl
derivative 5 (MeI/NaH, 67%), and the 2-acetate 6 (acetic
anhydride/pyridine, 76%). The thiophenyl group was now
removed using aqueous NBS to provide an inseparable
mixture of a:b anomers of the 2-methyl-derivative 7
(Scheme 2) (ratio around 1:1, anomeric 1H singlet and
doublet J¼1.2 Hz); and a 6:1 ratio of anomers (major
anomer 1H singlet and minor anomer 1H doublet J¼1.2 Hz)
of the 2-acetate 11 (again inseparable by flash chromato-
graphy), in yields of around 60–80% in each case.
Presumably formation of an intermediate acetoxonium
species improves the stereoselectivity for the formation of
the a-anomer of 11.
The homochiral hydroxycyclopent-2-enylacetate derivative
17 was prepared according to our optimisation14 of an
earlier preparation.15
A Mitsunobu reaction with the phenol 8 which had been
previously12 synthesised by us was carried out on the free
anomeric alcohols 7 (DEAD, Ph3P, THF), and a 3:1 ratio of
anomers of the protected CD-ring analogue 9 was obtained
(in 83% yield). Removal of the bis-acetal using brief
exposure to aqueous TFA provided a 3:1 anomeric mixture
of the desired CD-ring analogue 10 (63%). These anomers
were separated and NMR analysis suggested that the minor
product was the desired a-anomer, since the relative
d-values for H-5 were 4.2 ppm (minor compound) and
3.1 ppm (major compound) reflecting the anisotropic effect
of the aryl group upon H-5. In contrast, a Mitsunobu
reaction on anomeric alcohols 11 provided none of the
desired product, but reaction of the trichloroimidates 12
with the phenol 8 produced the protected CD-ring analogue
13. Removal of the bis-acetal (as before) provided the other
CD-ring analogue 14 as one pure anomer in an overall yield
of 19% for the three steps. Since H-5 resonated at 4.2 ppm,
we believe this to be the a-anomer, and this would be
consistent with participation of an acetoxonium inter-
mediate. While the yields of these reactions clearly require
With these key substrates in hand, we employed the fully
protected thioacetal of N-phthalimidoglucosamine 18
(prepared according to Scheme 4) as a model carbohydrate
for investigation of the coupling methodology.
Reaction of this thioacetal with (1R,3S)-(þ)-1-acetoxy-
cyclopent-2-en-3-ol 17 in the presence of N-iodosuccini-
mide and catalytic BF3 etherate16 yielded the desired
glycoside 19 (R¼triethylsilyl) exclusively as the b-anomer.
Unfortunately, during the work-up, one or more of the
triethylsilyl protecting groups were lost and a complex
mixture of products was obtained. In consequence, the fully
benzylated thioglycoside 20 (R¼benzyl) was prepared and
this could be converted into the glycoside 21 (R¼benzyl)
(60%). Removal of the acetate with methanolic potassium
carbonate to yield 22 was followed by coupling with 16
using DCC and DMAP in dichloromethane and thence
conversion into the desired naphthoate ester 23 (60%)
(Scheme 5). This was treated with Pearlman’s catalyst

A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
4021
Scheme 2.

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A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
Scheme 3. Reagents and conditions: (a) tert-butyl acrylate, Et3N, P(o-tol)3, Pd(OAc)2, 110 8C, 82%; (b) TFA, DCM, rt, quantitative; (c) CDI, magnesium
methyl malonate, THF, rt, 85%; (d) SO2Cl2, C6H6, 70 8C (85%); (e) hn, Et3N, MeOH, rt, 60%; (f) NaOH, 3:1 MeOH/H2O, 80 8C, 85%.
Scheme 4. (a) NaOH, phthalic anhydride, H2O, overnight, rt, quantitative; (b) Ac2O, pyridine, DMAP, overnight, 0 8C!rt, 72%; (c) EtSH, CHCl3, BF3·Et2O,
0 8C!rt, reflux 3 h, 70%; (d) NaOMe 25% (w/v) pH 8, MeOH, 90%; (e) triethylsilyltrifluoromethansulfonate, 2,6-lutidine, DMF, 0 8C, 4 h, 80%; (f) BnBr,
Bu4NI, NaH, DMF, 0 8C!rt, overnight, 60%.
(palladium hydroxide) in methanol and in atmosphere of H2
to provide the fully debenzylated adduct 24.
amounts of the desired analogue 15 (ESþ: 478.2). Clearly
further work will be required to optimise this chemistry.
Nonetheless, this work has established a viable route for the
synthesis of our core structure, and future work will seek to
produce a library of neocarzinostatin analogues in order to
establish the optimum structure required to maximise
binding to DNA.
Finally, removal of the phthalimide group was attempted
using methanolic hydrazine. However, although partial
hydrolysis was easily effected to provide the analogue 25
(ESþ: 640.2), further reaction led to production of only trace

A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
4023
˚
Scheme 5. (a) NIS, BF3·Et2O, 4 A MS, DCM, 20 min, 60%; (b) 1 M K2CO3, MeOH, 90%; (c) DCC, DMAP, 0 8C!rt, 60%; (d) Pd(OH)2, H2, EtOH, 60%.
2.1. Biological evaluation
The calicheamicin CD ring analogues 10 and 14 and the
neocarzinostatin core analogue 25 were evaluated for
cytotoxic activity against a range of cancer cell lines in vitro.
Cells were plated in RPMI1640 medium supplemented with
foetalcalf serumand 1%penicillin/streptomycin(1£103 cells/
well in 24 well plates). Following a 24 h attachment period at
378, the medium was removed from the wells and replaced
with 1 ml of medium containing the appropriate compound at
a range of concentrations. Cell counts were carried out using a
Coultercounterandcellgrowthcurveswereplottedfora7-day
period. While compounds 10 and 14 exhibited no significant
activity, compound 24 did exhibit modest activity at the level
of 50 mM.
This compares with the results of Caddick and co-workers
who reported17 very recently that the non-glycosyl-
ated analogue 26 exhibited activity against a range of
cancer cell lines with IC50s typically in the range
2.5–5.0 mM.
3. Experimental
3.1. General
IR were recorded using a Perkin–Elmer 881 series double

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A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
beam spectrophotometer, and samples were run as thin films
or in solution using NaCl plates. Low resolution and
accurate mass data were recorded on a VG Autospec
spectrometer and elemental analysis was carried out using a
Perkin–Elmer 2400 CHN Microanalyser by ASEP, Queen’s
University Belfast. All compounds for which accurate mass
data are provided were homogeneous by two-dimensional
NMR (CDCl3, 125 MHz): d 16.6, 17.8, 17.9, 47.7, 47.9,
58.5, 67.7, 68.6, 68.8, 80.5, 85.6, 99.5, 99.9, 127.2, 134.9.
HRMS (CI): calcd for C19H28O6S [Mþ] 384.1607. Found:
384.1595. [a]2D0¼2270.4 (c¼0.71, CHCl3). Mp¼124.4 8C.
3.1.3. 2-O-Acetyl-(20S) (30S)-phenyl-3,4-O-20,30-
dimethoxybutane-20,30-diyl-1-thio-a-L-rhamnopyrano-
side 6. (20S), (30S)-Phenyl-3,4-O- 20,30-dimethoxybutane-
20,30-diyl-1-thio-a-L-rhamnopyranoside 4(1.91 g.5.16 mmol)
was dissolved in pyridine (5.4 ml), and the reaction mixture
cooled to 0 8C. Acetic anhydride (1.47 ml) was added
dropwise, and the reaction mixture allowed to warm to room
temperature. After stirring at ambient temperature over-
night, TLC showed complete reaction. The reaction mixture
was then cooled to 4 8C, and quenched by the dropwise
addition of methanol (6 ml). The pyridine was then removed
under high vacuum and the residue was re-dissolved in
CH2Cl2 (60 ml). The organic layer was washed sequentially
with 1 M HCl (2£60 ml), sat. aq. NaHCO3 (1£60 ml), H2O
(1£60 ml) and brine (1£60 ml), dried over MgSO4, filtered
and concentrated under reduced pressure. Purification by
flash column chromatography yielded the desired com-
pound 6 as a white foam (1.61 g, 76%). IR (CHCl3) n: 2952,
1
TLC and exhibited no spurious signals in the H NMR
spectra at 300 MHz. NMR spectra were recorded using
Bruker DPX 300 and DRX 500 instruments. [a]D Values are
given in units of 1021deg cm2 g21. Solvents were dried by
distillation from calcium hydride (DCM, dichloromethane)
or from sodium-benzophenone (THF, diethyl ether). Petrol
refers to petroleum ether boiling range 40–60 8C.
Compound 3 was prepared according to Ref. 18.
3.1.1. (20S), (30S)-Phenyl-3,4-O-20,30-dimethoxybutane-
20,30-diyl-1-thio-a-L-rhamnopyranoside 4. Phenyl 1-thio-
a-L-rhamnopyranoside 3 (4.1 g, 16 mmol) was dissolved in
analar methanol (110 ml), and under a flow of argon,
trimethyl orthoformate (6.9 ml, 45.2 mmol), butan-2,3-
dione (1.76 ml, 20.1 mmol), and camphor sulphonic acid
(240 mg-catalytic) were added sequentially. The reaction
mixture was then refluxed for 72 h, after which time the
trans diol had been protected. Upon cooling, the reaction
was quenched by the addition of triethylamine to pH¼7, and
the solution was immediately concentrated onto flash silica
for purification. The title compound (4) was isolated as a
yellow foam (3.4 g, 58%). IR (CHCl3) n: 3450, 2949, 2833.
1H NMR (CDCl3, 500 MHz): d 1.26 (3H, d, J¼6.2 Hz,
C-5–CH3), 1.31, 1.32 (2s, 6H, C-20 –CH3, C-30 –CH3),
3.24, 3.30 (2s, 6H, C-20 –OCH3, C-30 –OCH3), 3.77 (at,
1H, J¼10.2 Hz, H-4), 3.97 (dd, 1H, J¼3.0, 10.2 Hz,
H-3), 4.18 (dd, 1H, J¼1.2, 3.0 Hz, H-2) 4.25 (m, 1H,
H-5), 5.49 (as, 1H, H-1) 7.24 (3H, m, S–C6H5), 7.44 (2H,
m, S–C6H5. 13C NMR (CDCl3, 500 MHz): d 16.4, 17.6,
17.7, 47.6, 48.1, 67.7, 68.5, 68.7, 71.4, 87.8, 99.8, 100.3,
127.3, 134.3. HRMS (CI): calcd for C18H26O6S [Mþ]
370.1450. Found: 370.1439. [a]2D0¼2300.0 (c¼1.31,
CHCl3).
1
1748, 1236. H NMR (CDCl3, 500 MHz): d 1.24 (d, 3H,
J¼6.2 Hz, C-5–CH3), 1.28, 1.31 (2s, 6H, C-20 –CH3, C-30 –
CH3), 2.13 (s, 3H, C-2–OCOCH3), 3.27, 3.29 (2s, 6H,
C-20 –OCH3, C-30 –OCH3), 3.71 (at, 1H, J¼10.2 Hz, H-4),
4.04 (dd, 1H, J¼3.2, 10.2 Hz, H-3), 4.25 (m, 1H, H-5) 5.29
(dd, 1H, J¼1.3, 3.2 Hz, H-2), 5.41 (as, 1H, H-1), 7.25 (3H,
m, S–C6H5), 7.44 (2H, m, S–C6H5). 13C NMR (CDCl3,
125 MHz): d 16.9, 17.9, 18.2, 21.6, 48.1, 48.5, 67.1, 68.3,
69.3, 72.8, 86.9, 100.2, 100.6, 128.0, 134.5, 170.9. HRMS
(CI): calcd for C19H25O6S1 (Mþ2OCH3) 381.1371. Found:
381.1359. [a]2D0¼2215.8 (c¼0.76, CHCl3).
3.1.4. 2-O-Methyl-(20S), (30S)-3,4-O-20,30-dimethoxy-
butane-20,30-diyl-L-rhamnopyranoside 7. Under a flow
of argon, the protected thioglycoside 5 (300 mg, 0.78 mmol)
was dissolved in analar acetone (10 ml), and cooled to 0 8C.
N-Bromosuccinimide (0.278 g, 1.56 mmol) was added
followed almost immediately by the addition of H2O
(0.5 ml). An immediate colour change from an orange
solution to a yellow solution was apparent. Stirring was
continued for a further 30 min, after which time a clear
solution showed the end of the reaction. The acetone was
removed under reduced pressure, and the residue re-
dissolved in EtOAc (50 ml). The organic layer was washed
with sat. aq. NaHCO3 solution (2£50 ml) and brine
(1£50 ml), dried (MgSO4), filtered, and immediately
concentrated onto flash silica for purification.
3.1.2. 2-O-Methyl-(20S), (30S)-phenyl-3,4-O-20,30-
dimethoxybutane-20,30-diyl-1-thio-a-L-rhamnopyrano-
side 5. The trans protected thioglycoside 4 (2.41 g,
65 mmol) in dry THF (50 ml) was added to sodium hydride
(4.62 g, 97.5 mmol) under a flow of argon. Iodomethane
(1.6 ml, 260 mmol) was then added dropwise, and the
reaction mixture stirred at ambient temperature for 2 h. The
reaction was then quenched by cooling the solution to 0 8C
followed by a slow dropwise addition of methanol (20 ml).
After evaporation to dryness, the residue was dissolved in
DCM (100 ml), and the organic layer sequentially washed
with H2O (2£100 ml) and brine (1£100 ml). It was then
dried (MgSO4), filtered and concentrated onto flash silica
for purification to yield the title compound as a pale yellow
crystalline solid (1.7 g, 67%). IR (CHCl3) n: 2949, 2832,
1259. 1H NMR (CDCl3, 500 MHz): d 1.28 (d, 3H,
J¼6.2 Hz, C-5–CH3), 1.31, 1.34 (2s, 6H, C-20 –CH3,
C-30 –CH3), 3.25, 3.31 (2s, 6H, C-20 –OCH3, C-30 –OCH3),
3.48 (s, 3H, C-2–OCH3) 3.73 (dd, 1H, J¼1.4, 3.0 Hz, H-2),
3.76 (at, 1H, J¼10.3 Hz, H-4), 3.95 (dd, 1H, J¼3.0,
10.3 Hz, H-3), 4.21 (m, 1H, H-5) 4.25 (d, 1H, J¼1.4 Hz,
H-1), 7.24 (3H, m, S–C6H5), 7.45 (2H, m, S–C6H5). 13C
An intractable mixture of anomers of unknown stereo-
chemistry was obtained, in a ratio of 1:1.2 (apparent from
NMR studies) (178 mg, 76%). It has been found that the
sugar proton signals for the two anomers, a, b, are
impossible to distinguish. However the major anomer
signals for other protons are highlighted in bold, and no
integration values are noted. IR (CHCl3) n: 3416, 2834,
1
1453. H NMR (CDCl3, 500 MHz): d 1.14 (d, J¼6.6 Hz,
C-5–CH3), 1.18 (d, J¼6.1 Hz, C-5–CH3), 1.21, 1.21 (2s,
C-20 –CH3, C-30 –CH3), 1.23, 1.25 (2s, C-20 –CH3, C-30 –
CH3), 3.17, 3.18 (2 s, C-20 –OCH3, C-30 –OCH3), 3.19, 3.20
(2s, C-20 –OCH3, C-30 –OCH3), 3.32–4.00 (m, C-2, C-3,

A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
4025
C-4, C-5), 3.44 (s, C-2–OCH3) 3.58 (s, C-2–OCH3), 4.66
(as, 1H, C-1), 5.17 (d, 1.2H, J¼1.2 Hz, C-1). 13C NMR
(CDCl3, 125 MHz): d 15.6, 15.7, 16.3, 16.4, 16.6, 16.7,
46.6, 46.7, 46.9, 58.3, 60.3, 66.0, 66.9, 67.0, 67.7, 69.6,
70.6, 77.8, 78.1, 91.9, 92.7, 98.5, 98.5, 98.7, 98.8. HRMS
(CI): calcd for C13H21O7 [Mþ2CH3] 277.1287. Found:
277.1274.
3.20, 3.21, 3.26 (4s, C-20 –OCH3, C-30 –OCH3), 3.17–4.30
(m, H-2, H-3, H-4, H-5), 3.48 (s, Ar–CO2CH3), 3.70 (s,
Ar–CO2CH3), 3.77 (s, Ar–OCH3), 3.80, 3.81 (2s,
Ar–OCH3), 3.84 (s, Ar–OCH3), 3.85 (s, C-2–OCH3),
3.86 (s, C-2–OCH3), 4.99 (d, 0.75H, J¼0.68 Hz, H-1), 5.50
(d, 0.25H, J¼1.34 Hz, H-1). 13C NMR (CDCl3, 62 MHz): d
15.5, 15.6, 16.7, 16.8, 16.9, 24.9, 46.7, 46.9, 47.1, 51.5,
59.9, 60.1, 60.3, 60.5, 66.8, 67.1, 68.7, 70.1, 70.5, 77.6,
77.8, 93.3, 98.5, 98.8, 98.9, 100.6, 102.3, 124.7, 132.7,
133.1, 142.4, 149.7, 150.7, 151.0, 166.7. HRMS (CI): calcd
for C24H35O11I 626.1224. Found: 626.1198.
3.1.5. 2-O-Acetyl-(20S) (30S)-3,4-O-20,30-dimethoxy-
butane-20,30-diyl-L-rhamnopyranoside 11. The thio-
glycoside 6 (1.61 g; 3.90 mmol) was dissolved in acetone
(50 ml), and cooled to 0 8C. N-Bromosuccinimide (1.42 g;
7.97 mmol) was added followed immediately by the
addition of H2O (1.42 ml). A colour change from an orange
solution to a yellow solution was apparent. Stirring was
continued for a further 30 min, after which time a clear
solution was visible. TLC showed formation of the desired
alcohol as well as the presence of unreacted starting
material. Stirring was continued for a further 30 min at
room temperature, however, no further change was
noted. The reaction mixture was immediately
concentrated onto silica for purification by flash column
chromatography. Yield 711 mg, (57%). The anomeric ratio
was 6:1, a/b. The 1H NMR signals are those for the
a-anomer. The only two discernible ‘b’ signals were those
of the anomeric proton and H-2, which are noted separately
3.1.7. Methyl 4-[2-O-methyl-L-rhamnopyranosyl]-oxy-5-
iodo-2,3-dimethoxy-6-methyl benzoate 10. Compound 9
(78 mg, 0.121 mmol) was cooled to 220 8C by placing the
flask in an acetone/dry ice bath. A 9:1 mixture of
trifluoroacetic acid/water (0.87 ml) was added dropwise
and the reaction mixture stirred at this temperature for 4 h.
After this time, TLC showed the formation of two anomers
and thus the reaction was quenched by allowing the reaction
mixture to warm to ambient temperature, and then
immediately removing the TFA under high vacuum. The
residue was then concentrated under reduced pressure onto
flash silica for purification by flash chromatography and
eluted with EtOAc to provide two anomers. Rf¼0.56 ‘a’ and
Rf¼0.41 b. Overall yield 40 mg, (63%); b 230 mg, (47%),
a 210 mg, (16%). b-Anomer. 1H NMR (CDCl3, 400 MHz):
d 1.29 (d, 3H, J¼6.2 Hz, C-5–CH3), 2.35 (s, 3H, Ar–CH3),
3.11 (m, 1H, H-5), 3.38 (at, 3H, J¼9.1 Hz, H-4), 3.47 (dd,
1H, J¼3.6, 9.1 Hz, H-3), 3.84 (s, 3H, Ar–CO2CH3), 3.89,
3.89 (2s, 6H, Ar–OCH3), 3.93 (s, 3H, C-2–OCH3), 4.00
(dd, 1H, J¼0.63, 3.6 Hz, H-2), 5.10 (as, 1H, H-1). 13C NMR
(CDCl3, 100 MHz): d 17.4, 25.9, 52.6, 61.1, 61.5, 62.4,
72.4, 73.9, 74.1, 80.1, 94.7, 103.6, 126.1, 133.9, 143.6,
150.7, 151.6, 167.7. [a]2D0¼219 (c¼1.0, MeOH).
a-Anomer. IR (CHCl3) n: 3475, 2939, 1750, 1452. 1H
NMR (CDCl3, 500 MHz) d: 1.25 (d, 3H, J¼6.9 Hz, C-5–
CH3), 2.37 (s, 3H, Ar–CH3), 3.49 (at, 3H, J¼8.0 Hz, H-4),
3.56 (s, 3H, Ar–CO2CH3), 3.84, 3.89 (2s, 6H, Ar–OCH3),
3.93 (s, 3H, C-2–OCH3), 3.56–3.93 (m, 1H, H-2), 4.07 (dd,
1H, J¼3.3, 9.8 Hz, H-3), 4.20 (m, 1H, H-5), 5.66 (as, 1H,
H-1). 13C NMR (CDCl3, 100 MHz) d: 17.4, 25.9, 52.7, 59.0,
61.1, 61.6, 71.1, 72.8, 80.6, 93.4, 100.5, 125.6, 134.5, 143.2,
151.3, 151.9, 168.0. HRMS (CI): calcd for C18H25O9I [Mþ]
512.0543. Found 513.0616. [a]D¼211.4 (c¼0.66, MeOH).
1
below. IR (CHCl3) n: 3440, 2932, 1732, 1373. H NMR
(CDCl3, 300 MHz): d 1.26 (d, 3H, J¼6.2 Hz, C-5–CH3),
1.27, 1.29 (2s, 6H, C-20 –CH3, C-30 –CH3), 2.15 (s, 3H,
C-2–OCOCH3), 3.25, 3.26 (2s, 6H, C-20 –OCH3, C-30 –
OCH3), 3.63 (at, 1H, J¼10.0 Hz, H-4), 4.00 (m, 1H, H-5),
4.14 (dd, 1H, J¼3.3, 10.0 Hz, H-3), 5.05 (dd, 1H, J¼1.5,
3.3 Hz, H-2), 5.15 (as, 1H, H-1). 13C NMR (CDCl3,
75 MHz): d 15.6, 16.7, 16.8, 20.2, 46.7, 47.0, 64.5, 65.6,
67.8, 70.2, 91.7, 98.7, 99.1, 169.8. b-anomer. 4.90 (d, 1H,
J¼1.2 Hz, H-1), 5.29 (dd, 1H, J¼1.2, 3.1 Hz, H-2). HRMS
(CI): calcd for C13H21O7 (Mþ2OCH3) 289.1287. Found:
289.1285.
3.1.6. Methyl 4-[2-O-methyl-(20S), (30S)-3,4-O- 20,30-
dimethoxybutane-20,30-diyl-L-rhamnopyranosyl]-oxy-5-
iodo-2,3-dimethoxy-6-methyl benzoate 9. Under a flow of
argon, the phenol 8 (80 mg, 0.23 mmol) and the alcohol 7
(100 mg, 0.34 mmol) were dissolved in dry THF (2 ml) and
triphenylphosphine (89 mg, 0.34 mmol) was added. The
reaction mixture was then cooled to 0 8C, and DEAD
(53.8 ml, 0.34 mmol) was added dropwise. The reaction
mixture was then allowed to warm to room temperature and
stirred at ambient temperature for 72 h. TLC showed major
conversion to a new product, running between the alcohol
and the phenol. This was then followed by the removal of
solvents under reduced pressure and concentration onto
flash silica for purification, yielding the title compound as a
yellow oil (119 mg, 83%).
3.1.8. 2-O-Acetyl-(20S) (30S)-3,4-O-20,30-dimethoxy-
butane-20,30-diyl-1-O-trichloroimidate-L-rhamno-
pyranoside 12. Under a flow of argon, the alcohol 11
(200 mg, 0.625 mmol) was dissolved in dry CH2Cl2 (4 ml),
and trichloroacetonitrile (0.62 ml, 6.25 mmol) was added.
After cooling to 212 8C, a catalytic amount of DBU
(4.6 mg) in dry CH2Cl2 (1 ml) was added dropwise. Stirring
was then continued at this temperature for 45 min. TLC
showed complete disappearance of starting material, and so
the reaction mixture was immediately concentrated onto
flash silica for purification to yield 181 mg, (62%) of the
trichloroimidates.
The following data shows an intractable mixture of
anomers. It can be clearly seen from the 1H NMR spectrum
that there is a mixture in a ratio of 3:1, and investigation of
the coupling constants reveals a probable ratio of 3:1, b/a.
The signals for the major b-anomer in the proton spectrum
are highlighted in bold type. IR (CHCl3) n: 2946, 1734,
1457. 1H NMR (CDCl3, 300 MHz): d 1.26–1.36 (m, C-5–
CH3, C-20 –CH3, C-30 –CH3), 2.29, 2.30 (2s, Ar–CH3), 3.17,
1
Due to the instability of the trichloroimidate the H NMR
spectrum was the only characterisation carried out on this
compound. The spectrum only showed the presence of one
anomer which was probably the b-anomer. 1H NMR

4026
A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
(CDCl3, 300 MHz) d: 1.27, 1.30 (2s, 6H, C-20 –CH3,
C-30 –CH3), 1.33 (d, 3H, J¼6.2 Hz, C-5–CH3), 2.17 (s,
3H, C-2–OCOCH3), 3.26, 3.27 (2s, 6H, C-20 –OCH3, C-30 –
OCH3), 3.72 (at, 1H, J¼10.1 Hz, H-4), 3.99 (m, 1H, H-5),
4.13 (dd, 1H, J¼3.4, 10.1 Hz, H-3), 5.25 (dd, 1H, J¼1.5,
3.4 Hz, H-2), 6.19 (d, 1H, J¼1.5 Hz, H-1), 8.62 (bs, 1H,
N–H).
3.1.11. 3-(40-Methoxy-20-methyl-phenyl)-acrylic acid
tert-butyl ester. A mixture of 4-bromo-3-methylanisole
(5 ml, 3.48 mmol), tri-o-tolylphosphine(423 mg,1.39 mmol),
tert-butylacrylate (7.6 ml, 0.05 mol), Et3N (5.8 ml,
4.20 mmol) and Pd(OAc)2 all dissolved in anhydrous DMF
(14 ml), was heated at 110 8C. After 30 min a precipitate had
formedand theheatingwascontinuedfor 2 h,thenthereaction
mixture was cooled and EtOAc was added. The reaction was
washed with water, sat. NaHCO3 solution, brine and the
organic extract was dried (MgSO4) and the solvent removed
under reduced pressure. The residue was purified by column
chromatography (eluent: petrol/ether, 95:5) to give the
unsaturated ester as a white solid. Yield: 7.1 g (82%). Rf:
0.62 (petrol/ethyl acetate, 9:1). IR (CHCl3): n 2976, 1704,
1604, 1256, 1147, 863. 1H NMR (CDCl3, 500 MHz): d 1.53
(9H, s, tert-butyl), 2.41 (3H, s, CH3), 3.80 (3H, s, OMe), 6.20
(1H, d, J¼15.80Hz, H-2), 6.75 (2H, m, H-50/30), 7.50 (1H, d,
J¼8.5 Hz, H-6 ), 7.83 (1H, d, J¼15.8 Hz, H-3). 13C NMR
(CDCl3, 125 MHz): d 20.3, 55.8, 112.0, 115.5, 118.4, 126.2
127.9 139.53, 140.8, 160.8, 166.8. m/z (EI): 248 ([M]þ, 17%),
192 (55), 175 (58), 147 (60), 132 (95), 104 (55), 77 (95), 56
(100). HRMS (EI): calcd for C15H20O3 [M]þ: 248.1412.
Found: 248.1418. Mp: 44–46 8C (lit.13 39 8C).
3.1.9. Methyl 4-[2-O-acetyl-(20S), (30S)-3,4-O-20,30-
dimethoxy butane-20,30 diyl-a-L-rhamnopyranosyl]-
oxy-5-iodo-2,3-dimethoxy-6-methyl benzoate 13. Under
an argon atmosphere, the imidate 12 (90 mg, 0.20 mmol),
˚
the phenol (52 mg, 0.15 mmol), and 4 A molecular sieves
(300 mg), were stirred in dry CH2Cl2 (2 ml) for 1 h at
ambient temperature. The reaction mixture was then cooled
to 270 8C, and boron trifluoride diethyl etherate (28 ml,
0.22 mmol) was added dropwise. With constant monitoring
by TLC, the reaction mixture was allowed to warm to
250 8C over a period of 1 h. With the formation of the
desired glycosylated compound apparent by TLC, the
reaction was quenched by the addition of solid NaHCO3
(10 mg) at 250 8C, followed by further warming to 220 8C
and final addition of H2O (1 ml). The reaction mixture was
then diluted with CH2Cl2, the organic layer washed with sat.
aq. NaHCO3 (2£20 ml), dried over MgSO4, filtered and
concentrated onto flash silica for purification to yield 85 mg,
(86%) of 13. IR (CHCl3) n: 3054, 2987, 1734, 1653, 1457.
1H NMR (CDCl3, 500 MHz) d: 1.26 (d, 3H, J¼6.4 Hz,
C-5–CH3), 1.30, 1.32 (2s, 6H, C-20 –CH3, C-30 –CH3), 2.17
(s, 3H, C-2–OCOCH3), 2.36 (s, 3H, Ar–CH3), 3.27, 3.32
(2s, 6H, C-20 –OCH3, C-30 –OCH3), 3.75 (at, 1H,
J¼10.1 Hz, H-4), 3.83 (s, 3H, Ar–CO2CH3), 3.87 (s, 3H,
Ar–OCH3), 3.91 (s, 3H, Ar–OCH3), 4.33 (m, 1H, H-5),
4.48 (dd, 1H, J¼3.3, 10.1 Hz, H-3), 5.50 (dd, 1H, J¼1.6,
3.3 Hz, H-2), 5.59 (d, 1H, J¼1.6 Hz, H-1). 13C NMR
(CDCl3, 125 MHz) d: 16.7, 17.7, 17.8, 21.1, 25.3, 47.7,
48.2, 61.0, 61.6, 61.7, 65.8, 68.3, 69.6, 70.6, 93.1, 100.0,
100.9, 101.0, 125.5, 134.1, 142.7, 150.5, 151.2, 167.7,
170.3. HRMS (CI): calcd for C24H32O11I (Mþ2OCH3)
623.0989. Found: 623.1012. [a]2D0¼256.1 (c¼0.66,
CHCl3).
3.1.12. 2-Deoxy-2-phthalimido-D-glucopyranose. D-Gluco-
samine hydrochloride (1.0 g, 4.64 mmol) was dissolved in a
1 M solution of NaOH (240 mg, 5.8 mmol) in water (6.0 ml)
and then phthalic anhydride (756 mg, 5.10 mmol) was
added. The reaction mixture was left overnight at room
temperature. The following day the reaction mixture was
washed with diethyl ether to eliminate the excess of phthalic
anhydride and then the water was concentrated under
reduced pressure to give a white foam. The product was a
mixture of a and b anomers in the ratio (a/b¼1:1). Yield:
quantitative. IR (KBr): n 3420, 1636, 1586, 1559, 870, 839,
753, 696.
NMR data. The integration values below are not related to
the a/b ratio. The integration values given treat the two
1
anomers as separate compounds in an equal amount. H
NMR (D2O, 500 MHz): d 3.50–3.90 (11H, b H-2, a H-3, b
H-3, a H-4, b H-4, a H-5, b H-5, a H-6, b H-6, a H-60, b
H-60), 4.05 (1H, dd, J¼10.6, 3.5 Hz, a H-2), 4.83 (1H, d,
J¼8.4 Hz, b H-1), 5.32 (1H, d, J¼3.5 Hz, a H-1), 7.49–
7.54 (6H, m, Phth.–CH), 7.65 (2H, m, H–Ar). 13C NMR
(D2O, 125 MHz): d 57.6 (a C-2), 60.7, 63.4, 63.6, 72.6,
73.0, 74.0, 74.6, 75.0, 77.2, 79.0, 93.8, 97.6, 130.2, 130.2,
131.3, 131.36, 132.77, 133.10, 133.39, 133.46, 137.39,
139.51, 176.30, 176.38, 178.22, 178.51. HRMS (EI): calcd
for C14H15NO7 [M]þ: 309.0848. Found: 309.0841.
3.1.10. Methyl 4-[2-O-acetyl-a-L-rhamnopyranosyl]-
oxy-5-iodo-2, 3-dimethoxy-6-methyl benzoate 14. A
dropwise addition of a 9:1 mixture of trifluoroacetic acid/
H2O (0.42 ml) to the acetal 14 (40 mg, 0.0611 mmol) was
carried out at ambient temperature. After stirring for 1 min,
the reaction was quenched by removing the TFA under high
vacuum. The residue was then concentrated onto flash silica
and purified using column chromatography (100% EtOAc),
and the title compound was isolated as a white foam.
Yield¼30 mg, (91%). IR (CHCl3) n: 3441, 2937, 1773,
1460. 1H NMR (CDCl3, 400 MHz) d: 1.30 (d, 3H,
J¼6.2 Hz, C-5–CH3), 2.17 (s, 3H, C-2–OCOCH3), 2.36
(s, 3H, Ar–CH3), 3.59 (at, 1H, J¼9.6 Hz, H-4), 3.84 (s, 3H,
Ar–OCH3), 3.87 (s, 3H, Ar–OCH3), 3.92 (s, 3H, Ar–CO2-
CH3), 4.20 (m, 1H, H-5), 4.40 (dd, 1H, J¼3.6, 9.6 Hz, H-3),
5.53 (dd, 1H, J¼1.7, 3.6 Hz, H-2), 5.72 (d, 1H, J¼1.7 Hz,
H-1). 1H NMR (CDCl3, 100 MHz) d: 17.5, 21.0, 25.9, 52.6,
61.0, 61.6, 70.1, 70.7, 72.0, 73.0, 92.9, 100.1, 125.5, 134.3,
142.7, 150.5, 151.2, 167.7, 170.8. HRMS (CI): calcd for
C19H25O10I [MþþNH4þ] 558.0835. Found: 558.0825.
[a]2D0¼220.7(c 0.58, MeO).
3.1.13. 1,3,4,6-Tetra-O-acetyl-2-deoxy-2-phthalimido-D-
glucopyranoside. 2-Deoxy-2-phthalimido-D-glucopyranose
(2.8 g, 9.38 mmol) was dissolved in pyridine (30 ml) and
the solution was cooled to 0 8C. Acetic anhydride
(48.80 mmol, 4.5 ml) was added dropwise with a catalytic
amount of DMAP. The reaction mixture was then left at
room temperature overnight. The following day the starting
material had disappeared and the reaction was quenched by
addition of MeOH (5 ml) at 0 8C. After evaporation of the
solvents under reduced pressure, the pyridine was removed
under high vacuum. The resultant oil was diluted with DCM
and the organic phase was washed sequentially with 1 M

A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
4027
HCl (3£80 ml), sat. aq. NaHCO3 (2£80 ml), H2O (1£80 ml)
and brine. After drying with MgSO4 the extract was filtered
and concentrated under pressure. Purification was carried
out by flash chromatography (petrol/EtOAc, 6:4) to give a
white solid as a mixture of anomers in the ratio (a/b, 1.5:1).
Yield: 3.2 g (72%). IR (DCM): n: 2940, 1755, 1721.
starting material. The reaction mixture was neutralised with
acid ion exchange resins, the solvent was evaporated and the
crude product was purified by flash chromatography
(EtOAc¼100%) to give the target compound. Yield: 9.5 g
(90%). Rf: 0.42 (EtOAc¼100%). IR (CHCl3): n 3420, 1711,
1
1388. H NMR (CDCl3, 500 MHz): d 1.13–1.16 (3H, t,
J¼7.4 Hz, CH2CH3), 2.58–2.69 (2H, m, CH2CH3), 3.45–
3.48 (1H, m, H-5), 3.067 (1H, at, J¼5.5 Hz, H-4), 3.86–4.15
(2H, m, H-6 and H-6 ), 4.10–4.15 (1H, m, H-2), 4.29–4.33
(1H, at, J¼9.6 Hz, H-3), 5.31 (1H, d, J¼10.4 Hz, H-1),
7.68–7.72 (2H, m, Phth.–CH), 7.72–7.81 (2H, m, Phth.–
CH). 13C NMR (CDCl3, 75 MHz): d 14.9, 21.0, 55.8, 61.9,
71.2, 72.6, 79.6, 81.3, 123.4, 123.8, 131.7, 134.1, 168.3,
168.5. m/z (ESþ): 376.4 ([MþþNa). CHN: C, 54.50; H,
5.57; N, 3.81. C16H19NO6S requires C, 54.38; H, 5.42; N,
3.96%. [a]D¼þ8.73 (c 0.91, DCM).
NMR data. The integration values below are not related to
the a/b ratio. The integration values given treat the two
anomers as separate compounds in an equal amount. H
1
NMR (CDCl3, 500 MHz): d 1.87–2.12 (24H, a, b-CH3),
4.04 (1H, m, b-H-5), 4.13–4.15 (2H, m, a, b-H-6), 4.20
(1H, m, a-H-5), 4.35–4.38 (2H, dd, J¼12.4, 4.2 Hz, a,
b-H-60), 4.47–4.50 (1H, at, J¼8.9 Hz, b-H-2), 4.71–4.74
(1H, dd, J¼11.57, 3.4 Hz, a-H-2), 5.15–5.21 (1H, a, b-H-
4), 5.87–5.89 (1H, at, J¼9.1 Hz, b-H-3), 6.28 (1H, d,
J¼3.4 Hz, a-H-1), 6.52 (1H, d, J¼8.9 Hz, b-H-1),
6.54–6.58 (1H, at, J¼9.1 Hz, a-H-3), 7.74–7.76 (4H, m,
a, b-Phth.–CH), 7.84–7.88 (4H, m, a, b-Phth.–CH). 13C
NMR (CDCl3, 125 MHz): d 20.4, 21.0, 52.9, 53.6, 61.6,
67.0, 68.4, 69.4, 70.2, 70.6, 72.7, 89.8, 90.6, 123.7, 123.8,
131.2, 131.3, 134.47 (a, 167.39–170.65 (a, b-CvO). m/z
(ESþ): 500.3 ([MþþNa).
3.1.16. Ethyl-2,3,4-tri-O-triethylsilyl-2-deoxy-2-phthali-
mido-1-thio-b-glucopyranoside 18. Ethyl-2-deoxy-2-
phthtalimido-1-thio-b-glucopyranoside (530 mg, 1.50 mmol)
was dissolved in DMF (10.0 ml) and the solution was cooled
to 278 8C. 2,6-Lutidine (1.6 ml, 13.41 mmol) and TESOTf
(2.0 ml, 8.94 mmol) were then added. The reaction mixture
was left for 3 h at 0 8C, it was then diluted with a sat.
NaHCO3 sol. and extracted with EtOAc. The organic phase
was washed with water, the solvent was concentrated in
vacuo and the crude was purified by flash column (petrol/
EtOAc, 93:7) to afford a white foam. Yield: 830 mg (80%).
Rf: 0.45 (petrol/EtOAc, 95:5). IR (CHCl3) n: 2955, 2877,
1778, 1716, 1386, 1111, 1009, 974. 1H NMR (CDCl3,
500 MHz): d 0.36–0.43 (6H, m, CH2), 0.62–0.66 (9H, m,
CH3), 0.72–0.78 (12H, m, CH2), 0.97–1.00 (18H, t, J¼
8.00 Hz, CH3), 1.14 (3H, t, J¼7.4 Hz, S–CH3), 2.58–2.67
(2H, m, S–CH2), 3.36 (1H, m, H-5), 3.67–3.70 (1H, t,
J¼9.6 Hz, H-4), 3.82–3.88 (2H, m, H-6 and H-60), 4.13–
4.17 (1H, t, J¼10.4 Hz, H-2), 4.43–4.47 (1H, t, J¼9.6 Hz,
H-3), 5.18 (1H, d, J¼10.4 Hz, H-1), 7.73–7.87 (4H, 2£m,
Phth.–CH). 13C NMR (CDCl3, 500 MHz): d 4.62, 7.1, 14.7,
23.5, 56.9, 62.2, 73.1, 75.0, 80.5, 81.2, 123.4, 132.0, 134.1,
168.1, 168.8. m/z (ESþ): 718.3 ([M]þþNa). CHN: C, 58.55;
H, 8.71; N, 2.05. C34H61NO6SSi3 requires C, 58.67; H, 8.84;
N, 2.01%. [a]2D4¼þ20.0 (c 0.25, CHCl3).
3.1.14. Ethyl-3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-
1-thio-b-glucopyranoside. 1,3,4,6-Tetra-O-acetyl-2-deoxy-
2-phthalimido-D-glucopyranoside (6.5 g, 13.70 mmol) was
dissolved in CHCl3 (80 ml) and BF3·Et2O (5.50 ml,
44.0 mmol) was added dropwise at 0 8C. The reaction
mixture was stirred for 30 min at room temperature. Then
EtSH (1.5 ml, 20.5 mmol) was added dropwise. The
reaction was left for 2 h at room temperature and then
refluxed for 4 h until disappearance of the starting material.
The reaction was quenched with sat. sol. NaHCO3 at 0 8C,
extracted with DCM and washed with NaHCO3 and water.
The organic layers were dried over MgSO4, the solvent was
evaporated and the crude product was purified by flash
column (petrol/EtOAc, 8:2) to give the b-anomer as a white
solid. Yield: 4.6 g (70%). IR (DCM): n 1750, 1718, 1636,
1
1387, 914, 722. H NMR (CDCl3, 500 MHz): d 1.21–1.24
(3H, t, J¼13.5 Hz, CH2CH3), 1.87–2.04–2.11 (3H, 3£s,
COCH3), 2.63–2.74 (2H, m, CH2CH3), 3.90–3.91 (1H, m,
C-5), 4.17–4.19 (1H, brd, J¼11.9 Hz, H-6), 4.30–4.33 (1H,
dd, J¼4.4, 11.9 Hz, H-60), 4.38–4.42 (1H, t, J¼20.6 Hz,
H-2), 5.17–5.20 (1H, t, J¼18.8 Hz, H-4), 5.48–5.50 (1H, d,
J¼10.5 Hz, H-1), 5.82–5.85 (1H, t, J¼19.2 Hz, H-3), 7.73–
7.76 (2H, m, Phth.–CH), 7.84–7.86 (2H, m, Phth.–CH).
13C NMR (CDCl3, 125 MHz): d 15.3, 20.8, 21.0, 21.1, 24.7,
54.0, 62.7, 69.3, 71.9, 76.3, 81.6, 124.1, 131.5, 132.0, 134.7,
167.5, 168.2, 169.9, 170.5, 171.1. HRMS (EI): calcd for
C20H20NO9 [Mþ2SEt], 418.1138. Found 418.1134. Mp:
115–116 8C. CHN; calcd for C22H25NO9S: C, 55.10%;
H, 5.25%; N, 2.92%. Found: C, 55.19%; H, 5.24%,
N, 2.92%. [a]2D4¼þ39.5 (c 0.6, DCM). HRMS (EI):
calcd for C14H20O9 [MþþNHþ4 ]: 350.1451. Found:
350.1464.
3.1.17. 1-O-[(10R,40S)-40-Acetoxy]-cyclopent-20-enyl-b-2-
phthalimido-3,4,6-tri-O-triethylsilyl-b-glucopyranoside
19. Ethyl 2,3,4-tri-O-ethylsilyl-2-deoxy-2-phthalimido-1-
thio-b-glucopyranoside (100 mg, 0.14 mmol) and (1R,4S)-
(þ)-4-hydrocyclopent-2-enylacetate (20 mg, 0.14 mmol)
were stirred in DCM (4 ml) in the presence of chopped
˚
MS 4 A (100 mg) for 20 min. The reaction mixture was
cooled to 230 8C and NIS (97 mg, 0.43 mmol) was added
and after 5 min. BF3·Et2O (5 ml, 0.04 mmol) was added.
After 30 min the reaction was quenched with a 10% sol. of
Na2S2O3, washed with sat. NaHCO3 sol. and extracted with
EtOAc. The solvent was evaporated and the crude mixture
was purified by flash chromatography (petrol/EtOAc,
98:2!9:1) to give a colourless oil. Yield: 30 mg (25%).
Rf: 0.23 (petrol/EtOAc, 9:1). IR (CHCl3) n: 2955, 2878,
1734, 1717, 1386, 1240, 1065, 828. 1H NMR (CDCl3,
500 MHz): d 0.36–0.43 (6H, m, TES–CH2), 0.63–0.66
(9H, m, TES–CH3), 0.72–0.78 (12H, m, TES–CH2), 0.97–
1.00 (18H, m, TES–CH3), 1.61–1.66 (1H, m, H-50), 1.95
(3H, s, OAc), 2.63–2.66 (1H, m, H-50), 3.24 (1H, m, H-5),
3.1.15. Ethyl 2,3,4-hydroxyl-2-deoxy-2-phthtalimido-1-
thio-b-glucopyranoside. Ethyl-3,4,6-tri-O-acetyl-2-deoxy-
2-phthalimido-1-thio-b-glucopyranoside (14.0 g, 0.03 mol)
was dissolved in MeOH and a few drops of NaOMe 25%
sol. in MeOH was added until pH 8 was obtained and left to
stir for 4 h at room temperature until disappearence of the

4028
A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
3.66–3.69 (1H, at, J¼8.2 Hz, H-4), 3.82–3.85 (2H, m, H-6
and H-60), 4.02–4.07 (1H, at, J¼8.5 Hz, H-2), 4.36–4.40
(1H, at, J¼8.2 Hz, H-3), 4.45 (1H, m, CH–O–sug.), 5.18
(1H, d, J¼8.5 Hz, H-1), 5.35 (1H, m, CH–O–OAc), 5.74–
5.78 (2H, m, vCH), 7.73–7.87 (4H, 2£m, Phth.–CH). 13C
NMR (CDCl3, 125 MHz): d 4.61–7.1 (3£TES-C), 21.0,
29.7, 38.3, 57.8, 62.1, 73.3, 73.9, 76.6, 76.8, 81.0, 97.0,
123.2, 132.0, 132.9, 134.1, 135.7, 170.7. m/z (ESþ): 798.5
([MþþNa, 100%), 634.6 (40), 502.6 (65), 301.5 (18).
[a]2D4¼26.4 (c 0.46, CHCl3).
138.2 (25£C), 133.1, 133.7, 170.8 (3£C). HRMS (FAB):
calcd for C42H41NO9 [M]þ: 703.2781. Found: 703.2794.
[a]2D4¼þ6.1 (c 0.66, DCM).
3.1.20. 1-O-[(10R,40S)-40-Hydroxy]-cyclopent-20-enyl-b-
2,3,4-tri-O-benzyl-2-deoxy-2-phthalimido-b-glucopyra-
noside 22. Compound 21 (450 mg, 0.64 mmol) was
dissolved in MeOH and few drops of a 1 M sol. of K2CO3
were added until pH 8. After 3 h the solvent was evaporated,
EtOAc and water were added. The organic extracts were
dried over MgSO4, the solvent was evaporated in vacuum
and the crude product was purified by flash chromatography
(petrol/EtOAc, 6:4) to give the target compound. Yield:
380 mg (90%). Rf: 0.19 (petrol/EtOAc, 6:4). IR (CHCl3) n:
3.1.18. Ethyl 2,3,4-tri-O-benzyl-2-deoxy-2-phthtalimido-
1-thio-b-glucopyranoside 20. Ethyl 2-deoxy-2-phthtali-
mido-1-thio-b-glucopyranoside (2.70 g, 7.64 mmol), was
dissolved in DMF (30 ml). Tetrabutylammonium iodide
(TBAI) (300 mg, 0.76 mmol) and benzylbromine (5.71 ml,
45.88 mmol) were added. The solution was cooled down to
0 8C and then NaH (1.9 g, 45.88 mmol) was added slowly.
The reaction mixture was left for 1 hr. at 0 8C and stirred at
rt overnight. The following day the reaction was quenched
with NH4Cl sat. sol. and extracted with DCM. The organic
phase was washed with NH4Cl sat. sol. and brine. The
solvent was evaporated and the crude product was purified
by flash chromatography (petrol/EtOAc, 9:1) to give a white
foam. Yield: 2.9 g (60%). Rf: 0.85 (petrol/EtOAc, 75:25). IR
1
3470, 3030, 2870, 1774, 1713, 1389. H NMR (CDCl3,
500 MHz): d 1.57–1.61 (1H, dt, J¼14.4 Hz, 4.1, H-50),
2.58–2.64 (1H, m, H-50), 3.70 (1H, m, H-5), 3.73–3.77 (3H,
H-4 and CH2), 4.15–4.18 (1H, at, J¼8.5 Hz, H-2), 4.42
(1H, at, J¼8.5 Hz, H-3), 4.42–4.85 (8H, 2£Bn–CH2, H-6,
H-60, H-10 and H-40), 5.27 (1H, d, J¼8.5 Hz, H-1), 5.74 (1H,
d, J¼8.6 Hz, CHv), 5.81 (1H, d, J¼8.6 Hz, CHv), 6.86–
7.77 (19H, Bn–CH2 and Phth.–CH). 13C NMR (CDCl3,
125 MHz): d 41.7, 55.9, 68.8, 73.5, 74.8, 75.0, 75.1, 79.2,
79.7, 81.4, 97.1, 123.2–138.14 (25£C), 133.37, 137.60,
168.00. m/z (ESþ): 684.3 ([M]þþNa). [a]2D4¼þ186.6 (c
0.75, DCM).
1
(CHCl3) n: 3005, 2926, 1773, 1715, 1387, 720. H NMR
(CDCl3, 500 MHz): d 1.16–1.20 (3H, t, J¼7.4 Hz,
CH2CH3), 2.58–2.71 (2H, m, CH2CH3), 3.68 (1H, m,
H-5), 3.76–3.80 (3H, m, H-4 and Bn–CH2), 4.26 (1H, at,
J¼8.5 Hz, H-2), 4.37–4.84 (7H, 2£Bn–CH2, H-3, H-6,
H-60), 5.25 (1H, d, J¼10.4 Hz, H-1), 6.88–7.78 (19H,
3£Bn–CH2, 1£Phth.–CH). 13C NMR (CDCl3, 125 MHz):
d 14.9, 23.9, 54.9, 68.9, 73.4, 74.9, 75.01, 79.4, 79.5, 80.3,
81.0, 123.3–138.2 (24£C), 167.5, 168.0. HRMS (FAB):
calcd for C37H37NSO6 [M]þ: 623.2342. Found: 623.2360.
[a]2D4¼þ8.0 (c 0.75, DCM).
3.1.21. (40R,10S)-[40-(200-Hydroxy, 700-methoxy-500-methyl-
naphthoate)]-[10-O-1-3,4,6-tri-O-benzyl-2-deoxy-2-
phthalimido-b-glucosyl]-10,40-dihydroxy-cyclopentene
23. The previous product (1.62 g, 2.45 mmol), naphthoic
acid 16 (682 mg, 2.88 mmol) and DMAP (60 mg,
0.48 mmol) were dissolved in DCM (12.0 ml). The reaction
mixture was cooled to 0 8C and then DCC (740 mg,
3.60 mmol) was added. The reaction was left at 0 8C for
1 h and then at rt overnight. The following day the reaction
mixture was filtered, the solvent was concentrated in vacuo
and the crude product was purified by flash chromatography
(petrol/ EtOAc, 75:25) to give a white foam. Yield: 1.3 g
(60%). Rf: 0.48 (petrol/EtOAc, 7:3). IR (CHCl3) n: 3450,
2922, 1773, 1713, 1615, 1388. 1H NMR (CDCl3, 500 MHz):
d 2.05–2.10 (1H, dt, J¼14.8 4.1 Hz,), 2.60 (3H, s), 2.91–
2.95 (1H, m), 3.67 (1H, m), 3.71 (3H, s), 3.77 (3H), 4.13
(1H, at, J¼9.6 Hz), 4.41 (1H, at, J¼9.6 Hz), 4.55- 4.85 (7H,
m), 5.34 (1H, d, J¼8.5 Hz), 5.75 (1H, m), 5.97 (1H, d,
J¼5.7 Hz), 6.04 (1H, d, J¼5.7 Hz), 6.84–7.54 (21H, m),
7.98 (2H, m). 13C NMR (CDCl3, 125 MHz): d 19.9, 38.4,
55.1, 55.9, 68.8, 73.5, 74.8, 75.0, 76.8, 78.4, 79.3, 79.7,
81.2, 97.7, 104.5, 117.0, 122.9, 127.3, 127.6, 127.7, 127.8,
127.9, 128.0, 128.0, 128.4, 128.5, 132.4, 132.9, 133.6,
134.2, 136.4, 136.5, 137.9, 138.0, 138.1, 159.5, 164.5,
172.1. HRMS (FAB): calcd for C53H49NO11 [M]þ:
875.3305. Found: 875.3297. CHN: C, 72.15; H, 5.94; N,
1.91. C53H49NO11 requires C, 72.55; H, 5.64; N, 1.60%.
[a]2D4¼þ17.63 (c 0.7, DCM).
3.1.19. 1-O-[(10R,40S)-40-Acetoxy]-cyclopent-20-enyl-b-
2,3,4-tri-O-benzyl-2-deoxy-2-phthalimido-b-glucopyra-
noside 21. Ethyl 2,3,4-tri-O-benzyl-2-deoxy-2-phthtali-
mido-1-thio-b-glucopyranoside (570.0 mg, 0.91 mmol)
and (1R,4S)-(þ)-4-hydroxycyclopent-2-enylacetate (130.0 mg,
0.91 mmol) were dissolved in DCM (8.0 ml) and stirred for
10 min at rt. The reaction mixture was cooled to 230 8C and
˚
chopped 4 A molecular sieves (5700mg) and NIS (615 mg,
2.73 mmol) were added. After 10 at 230 8C BF3·Et2O
(23 ml, 0.18 mmol) was added and the reaction mixture was
left for 200 and then quenched with sodium thiosulfate 10%
sol. The solution was filtered, diluted with DCM and washed
with sodium sulfate, NaHCO3 sat. sol. and water. The
solvent was evaporated and the residue was purified by flash
chromatography (petrol/EtOAc, 8:2!7:3). Yield: 460 mg
(70%). Rf: 0.44 (petrol/EtOAc, 75:25). IR (CHCl3) n: 3030,
2868, 1776, 1732, 1714, 1389. 1H NMR (CDCl3, 500 MHz):
d 1.67–1.72 (1H, dt, J¼4.4 Hz, 14.6, H-50), 1.94 (3H, s,
CH3), 2.67–2.72 (1H, m, H-50), 3.65 (1H, m, H-5), 3.75–3.
78 (3H, m, H-3 and Bn–CH2), 4.18 (1H, at, J¼8.5 Hz, H-2),
4.30 (1H, at, J¼8.5 Hz, H-3), 4.42–4.85 (7H, H-6, H-60,
2£Bn–CH2 and H-10), 5.27 (1H, d, J¼8.5 Hz, H-1), 5.84
(1H, m, H-40), 5.77 (1H, brd, J¼5.6 Hz, CHv), 5.84 (1H,
brd, J¼5.6 Hz, CHv), 6.84–7.77 (19H, Bn–CH and
Phth.–CH). 13C NMR (CDCl3, 75 MHz): d 21.1, 38.2,
55.9, 68.7, 73.5, 74.8, 75.0, 79.2, 79.6, 81.1, 97.2, 123.2–
3.1.22. (40R,10S)-[4-(200-Hydroxy-700-methoxy-500-methyl-
naphthoate]-10-O-1-2-deoxy-2-phthalimido-b-glucosyl-
10,40-dihydroxy-cyclopentane 24. Pd(OH)2 20% (140 mg)
was dissolved in EtOH (8.0 ml). The previous product
(70 mg, 0.08 mmol) was added and then it was left to react
with H2 at rt under 1 atm pressure overnight. The following
day the solution was filtered through celite the solvent was

A. Cirla et al. / Tetrahedron 60 (2004) 4019–4029
4029
8. Coleman, R. S.; Perez, R. J.; Burk, C. H.; Navarro, A. J. Am.
Chem. Soc. 2002, 124, 13008.
evaporated and the crude product was purified by flash
chromatography (DCM/MeOH, 9:1). Yield: 30 mg (60%).
Rf: 0.47 (DCM/ MeOH, 9:1). IR (DCM) n: 3414, 2926,
9. Wender, P. A.; Harmata, M.; Jeffrey, D.; Mukai, C.; Suffert, J.
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Yamada, H.; Shiraki, T.; Suguira, Y. Angew. Chem., Int. Ed.
1993, 32, 1657. Matsumoto, Y.; Kuwatani, Y.; Ueda, I.
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1
1775, 1713, 1615, 1388. H NMR (CDCl3, 500 MHz): d
1.68–1.78 (2H, m), 2.06 (1H, m), 2.24–2.31 (2H, 2£m),
2.59 (3H, s, CH3), 2.82 (1H, m), 3.44–3.58 (3H, 2£m), 3.78
(3H, s, OCH3), 3.80 (1H, m), 4.00–4.04 (1H, at, J¼8.3 Hz),
4.13 (1H, m), 4.33 (1H, m), 5.32–5.36 (2H, m), 6.83 (1H, s),
6.93 (1H, d, J¼9.2 Hz), 7.47–7.60 (4H, m), 7.94 (1H, d,
J¼9.2 Hz), 7.99 (1H, s). 13C NMR (CDCl3, 125 MHz): d
19.9, 30.4, 30.8, 39.5, 55.3, 55.7, 62.0, 71.7, 72.2, 75.7,
79.2, 79.2, 97.2, 103.3, 104.7, 115.9, 116.9, 122.9, 124.0,
131.3, 132.1, 133.9, 134.3, 136.5, 159.4, 163.3, 168.3,
171.4. HRMS (FAB): calcd for C32H33NO11 [Mþ]:
607.2054. Found: 607.2049. [a]2D4¼264.8 (c 1.05, DCM).
Acknowledgements
A. Ciral thanks the McClay Trust for a PhD studentship,
A. McHale thanks the EPSCR and Dextra Laboratories,
and we thank Dr. Hendrik van den Berg for the in vitro
anti-cancer screening.
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