Synthesis of novel analogues of the calicheamicin γ1 and esperamicin A1B oligosaccharides

Article abstract of DOI:10.1039/b006113l

The chemical synthesis of three analogues of the calicheamicin γ₁ and esperamicin A_1B 2 oligosaccharides is described in which the carbohydrate ring E is replaced by a basic side chain E'. Our synthetic strategy begins with ABE' fragment construction which possesses an unusual β N-O glycosidic bond. Glycosylation of the nitrone 20 and the appropriate activated sugar B 13 or 22 gives the disaccharides 23 and 24 respectively. Esperamicin A_1B oligosaccharide analogue 5 is obtained after two deprotection steps of the fragment 24. After removal of the protecting groups of unit 23, the fully deprotected disulfide 33 is reduced and immediately coupled with the deprotected aromatic unit C 30 (or CD 31) to provide the calicheamicin γ₁ oligosaccharide analogues 3 and 4. We also report the synthesis of hemiacetal 7 in which the thioester function between the CD and B rings is replaced by an ester linkage. This arylsaccharide is a key intermediate required for the synthesis of a novel calicheamicin γ₁ analogue 6.

Full text of DOI:10.1039/b006113l

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I
Synthesis of novel analogues of the calicheamicin ꢀ1 and
esperamicin A1B oligosaccharides
Stéphane Moutela and Jacques Prandi*b
1
a Institut de Chimie Organique et Analytique, Université d’Orléans, BP 6759, F-45067 Orléans
Cedex 2, France. Fax: (33) 2-38-41-72-81; E-mail: stephane.moutel@univ-orleans.fr
b Institut de Pharmacologie et de Biochimie Structurale-CNRS, 205 route de Narbonne,
F-31077 Toulouse Cedex, France
Received (in Cambridge, UK) 28th July 2000, Accepted 27th November 2000
First published as an Advance Article on the web 16th January 2001
The chemical synthesis of three analogues of the calicheamicin γ1 I 1 and esperamicin A1B 2 oligosaccharides is
described in which the carbohydrate ring E is replaced by a basic side chain EЈ. Our synthetic strategy begins
with ABEЈ fragment construction which possesses an unusual β N–O glycosidic bond. Glycosylation of the nitrone
20 and the appropriate activated sugar B 13 or 22 gives the disaccharides 23 and 24 respectively. Esperamicin A1B
oligosaccharide analogue 5 is obtained after two deprotection steps of the fragment 24. After removal of the
protecting groups of unit 23, the fully deprotected disulfide 33 is reduced and immediately coupled with the
deprotected aromatic unit C 30 (or CD 31) to provide the calicheamicin γ1 I oligosaccharide analogues 3 and 4.
We also report the synthesis of hemiacetal 7 in which the thioester function between the CD and B rings is replaced
I
by an ester linkage. This arylsaccharide is a key intermediate required for the synthesis of a novel calicheamicin γ1
analogue 6.
into the minor groove of the DNA.6a,7 As a result of their
Introduction
potent biological activities, novel molecular architecture and
unusual mechanism of action, there has been considerable
interest shown by synthetic chemists in realising the total syn-
thesis of these molecules and in gaining further understanding
of the mechanism of action of this new class of natural
products.8
The nature of the calicheamicin and esperamicin DNA-
association is not fully understood and we wished to examine
which structural features of the carbohydrate domain of cali-
cheamicin γ1 I 1 and esperamicin A1B 2 are responsible for select-
ive DNA recognition. Previous works have determined the roles
of sugar rings D and E,4a,7a,9 the aromatic ring-C6b,10 and the
unusual β N–O glycosidic bond11 on the DNA–drug associ-
ation phenomenon. In conclusion of these studies, the β N–O
glycosidic bond, the iodide atom of ring-C, and the secondary
amine of carbohydrate ring E were found important for
DNA association. In this paper, we report the total synthesis of
Calicheamicin γ1 11 and esperamicin A1B 2,1c,2 isolated
respectively by fermentation of different strains of Micro-
monospora echinospora spp. Calichensis and Actinomadura
verrucosospora, are some of the most potent antitumor anti-
biotics ever discovered (Fig. 1). These compounds, which are
remarkable DNA-damaging agents, can initiate double-strand
I
DNA scission3 for calicheamicin γ1 and single-strand DNA
I
scission4 for esperamicin A1B. The chemical structure of cali-
cheamicins and esperamicins can be divided into two parts: the
enediyne bicyclic core which is responsible for DNA cleavage
following a Bergman cycloaromatisation5 mecanism and the
carbohydrate domain which plays a key role in the drug–DNA
interaction.6 For example, the oligosaccharide domain of
I
calicheamicin γ1 is largely responsible for the selectivity and
specificity of DNA cleavage, particularly towards TCCT,
TCTC,6a,7 TTTT3b sequences and has been shown to bind
Fig. 1
DOI: 10.1039/b006113l
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
This journal is © The Royal Society of Chemistry 2001
305

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Scheme 1 Reagents, conditions and yields: (i) CF3CH2SO2Cl, pyridine,
CH2Cl2, rt, 2 h; (ii) ClCH2CH2Cl, pyridine, water, reflux, 1 h, 68% from
8; (iii) BzCl, pyridine, rt, 5 h, 88%; (iv) water–AcOH 2:1, reflux, 2 h,
85% ; (v) Cl3CCN, DBU, CH2Cl2, rt, 1 h, 100%.
Fig. 2
1
judged by H NMR spectroscopy. Final activation of hemi-
acetal 12 using trichloroacetonitrile19 in the presence of
1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) furnished trichloro-
acetimidate 13.
oligosaccharides 3 and 412 which are analogues of the cali-
cheamicin γ1 oligosaccharide. To further understand the role
I
played by the sugar ring E on the DNA–drug association, we
chose to replace it by a basic chain EЈ with or without the
rhamnopyranosyl unit D. The oligosaccharide 5, which is an
analogue of esperamicin A1B oligosaccharide is also described
(Fig. 2). Our general strategy centres on the glycosylation of
the AEЈ moiety as a nitrone with thiosugar ring B using the
approach described in our laboratory.13 The final and crucial
step is based on the coupling of the fully deprotected disacchar-
ide ABEЈ with aromatic unit CD (or C) using the selective
formation of a thioester.14
The preparation of the nitrone 20 began with alkylation
of the known alcohol 1413 with 1,4-dibromobutane in the
presence of sodium hydride to give 15 in 61% yield (Scheme 2).
In spite of recent efforts to obtain information on the nature
of the association of calicheamicin with DNA,11b,11c,15 no
examples have been reported of the role played by the sulfur
atom of the thioester linkage in the selective drug-DNA
recognition. Hence we are also interested in the synthesis of
analogue 6 (Fig. 2) which possesses an ester linkage in place
of the thioester group found in the calicheamicins. We report
the synthesis of the hemiacetal 7,16 a key precursor required for
I
the synthesis of the novel calicheamicin γ1 oligosaccharide
analogue 6 (Fig. 2). A retrosynthetic analysis of the analogue 6
suggests that its oligosaccharide portion can be constructed
from the glycosylation of a nitrone AE with the hemiacetal 7.
Further disconnections led us to conclude that the hemiacetal
7 can be made from coupling of the arylrhamnopyranosyl
subunit CD with an appropriate sugar B.
Results and discussion
Our investigation began with the synthesis of sugar unit 13
(Scheme 1). This compound was prepared in 5 steps from the
known compound 817 using an intramolecular nucleophilic
substitution as the key step. Alcohol 8 was converted into the
2,2,2-trifluoroethanesulfonate18 9 using commercially avail-
able 2,2,2-trifluoroethanesulfonyl chloride in the presence of
pyridine. Subsequent heating of 9 at reflux in a mixture 1,2-
dichloroethane–pyridine–water gave thiol 1017 in 68% yield
over the 2 steps. Alcohol 8 was also successfully converted into
the corresponding tosyl ester (toluene-p-sulfonyl chloride,
pyridine, 60 ЊC, 18 h) in 76% yield but subsequent heating
(24 h) in an identical fashion to that described earlier failed to
effect conversion to thiol 10. In this case, no reaction could be
induced and the tosyl compound was recovered unchanged.
Next, benzoylation of thiol 10 gave sugar 11 in 88% yield,
which was subjected to acidic hydrolysis to provide the corre-
sponding hemiacetal 12 as a 1:3 mixture of α and β anomers as
Scheme 2 Reagents, conditions and yields: (i) 1,4-dibromobutane,
NaH, DMF, 0 ЊC, 3 h, 61%; (ii) EtNH2, rt, 10 h; (iii) FmocCl, K2CO3,
THF–water 2.5:1, 0 ЊC, 45 min, 76% from 15; (iv) NaBH3CN,
BF3 :Et2O, CH2Cl2, Ϫ30 ЊC, 4 h, 86%; (v) morpholine, rt, 2 h, 53%; (vi)
0.3 M HCl in MeOH–water 3:1, rt, 90 min; (vii) p-MeOC6H4CHO,
toluene, reflux, 1 h, 82% from 18; (viii) morpholine, rt, 2 h, 60%.
Displacement of the bromide 15 with a large excess of ethyl-
amine followed by protection of the secondary amine 16 with
a fluoren-9-ylmethoxycarbonyl protecting group gave the amine
17 in 76% yield over the 2 steps. Selective reduction of the oxime
bond of 17 with sodium cyanoborohydride in the presence
of boron trifluoride–diethyl ether furnished the hydroxylamine
18 in 86% yield.13,8i The presence of the Fmoc group com-
plicated NMR assignment at room temperature due to the
presence of rotamers;20 this group was thus removed to yield
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J. Chem. Soc., Perkin Trans. 1, 2001, 305–315

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the free amine 19. In the 1H NMR spectrum of this compound,
the appearance of a multiplet at δ 2.85, assigned to H-4, with
two large vicinal coupling constants (J3,4 = J5,4 = 10.0 Hz) and
a small vicinal coupling constant (JNH,4 = 4.0 Hz) confirmed
the desired D-gluco configuration. Acidic hydrolysis of ketal
18 followed by condensation of the resulting hydroxylamine
with p-methoxybenzaldehyde in toluene gave nitrone 20 in
82% yield from 18. The Fmoc-protected amine 20 was treated
with morpholine to yield the more readily characterisable free
amine 21.
Next, glycosylation of nitrone 20 with trichloroacetimidates
13 and 228i promoted by silver trifluoromethanesulfonate21
gave disaccharides 23 (92% yield) and 24 (76% yield)
respectively, both as inseparable mixtures of α and β anomers
(Scheme 3). The stereochemistry of the major component for
Scheme
5
Reagents, conditions and yields: (i) Me2SO4, K2CO3,
acetone, rt, 24 h, 94%; (ii) 2.5 M NaOH, reflux, 6 h, 95%; (iii)
PhOP(O)Cl2, pyridine, 1,2-dimethoxyethane (DME), rt, 1 h.
Scheme 3 Reagents, conditions and yields: (i) 20, AgOTf, CH2Cl2,
4Å molecular sieves, Ϫ20 ЊC, 2 h, 92% (for 13 → 23); 76% (for
22 → 24).
fully accomplished in the presence of two free sugar hydroxy
groups as described by Kahne and co-workers8h in the synthesis
of the calicheamicin γ1 I oligosaccharide.
The crucial step in our approach to the synthesis of
calicheamicin γ1 oligosaccharide analogues 3 and 4 was the
each disaccharide 23 and 24 was readily determined as having
the β-configuration as judged by the 1H NMR vicinal coupling
constants (J1B,2Bax = 10.5 Hz, J1B,2Beq = 2.0 Hz for 23 and 24).
In fact, each disaccharide consisted of four diastereoisomers
because of the creation of another chiral centre at the
N,O-acetal carbon atom. To account for the unusual selectivity
of these glycosylation reactions involving a 2-deoxyglycoside,22
a 1,3-participation of the benzoyl group at the C-3 position of
sugar B has been invoked.8h,23 A related observation has been
reported in a synthesis of digitoxin.24
I
selective coupling of mixed anhydrides 30 and 31 and the fully
deprotected disulfide 33. First, treatment of disaccharide 23
using the method described above for the preparation of
25β gave the desired β-anomer 32 (75%) and the unwanted
α-anomer (13%)26 separable after column chromatography
(Scheme 6). Surprisingly, treatment of the resulting β-anomer
Deprotection of the N,O-acetal within disaccharide 24 was
achieved using a catalytic amount of 2,3-dichloro-5,6-dicyano-
1,4-benzoquinone25 (DDQ) in aqueous acetonitrile (Scheme 4).
Scheme 4 Reagents, conditions and yields: (i) DDQ, CH3CN–water
9:1, 0 ЊC, 3 h, 65%; (ii) K2CO3, MeOH, rt, 2 h, 91%.
At this stage, column chromatography allowed separation of
the β-anomer 25 (48%) from the unwanted α-anomer (17%).26
Treatment of the resulting β-compound 25 with potassium
carbonate in anhydrous methanol effected simultaneous
deprotection of the Fmoc and benzoyl groups to give 5, the
analogue of esperamicin A1B oligosaccharide in 91% yield.
Scheme 6 Reagents, conditions and yields: (i) DDQ, CH3CN–water
9:1, 0 ЊC, 1 h, 88%; (ii) K2CO3, MeOH, rt, 2 h, 72%; (iii) Bun P, DME
0 ЊC, 1 h; then 30, rt, 24 h, 53%; (iv) Bun P, DME, 0 ЊC, 1 h;3then 31,
3
rt, 24 h, 72%.
I
Our efforts towards the synthesis of calicheamicin γ1 oligo-
saccharide analogues 3 and 4 carried on with the preparation
of ring C (and CD). Methylation of known phenol 2627 (94%
yield) followed by subsequent saponification of ester 27 pro-
vided the corresponding carboxylic acid 28 in 95% yield
(Scheme 5). Final activation of this carboxylic acid into
mixed anhydride 30 was accomplished using phenyl dichloro-
phosphate28 in the presence of pyridine. Using a similar
procedure, known 4-rhamnosyl-substituted benzoic acid 298h
was transformed into mixed anhydride 31. In this case it is
notable that the formation of the mixed anhydride was success-
32 under basic conditions as described earlier provided only the
disulfide 33 in 72% yield instead of the expected thiol. The
chemical structure of disulfide 33 was elucidated using mass
1
spectroscopy in conjunction with H NMR analysis. Signifi-
cantly, no doublet (J4,SH ≈ 10–15 Hz) at δ ≈ 1.60 due to the pres-
ence of a thiol proton was observed in the 1H NMR spectrum.
Disulfide 33 was reduced with a large excess of tri-n-butyl-
phosphine in 1,2-dimethoxyethane (DME) and then added to a
I
solution of mixed anhydride 30 to furnish the calicheamicin γ1
oligosaccharide analogue 3 in 53% yield. The same protocol
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
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I
using mixed anhydride 31 provided the calicheamicin γ1
B-ring which should give preferential β-glycoside formation
oligosaccharide analogue 4 in 72% yield. Both oligosaccharides
3 and 4 were thoroughly characterised, including 1D- and
2D-NMR analysis. Thioester-bond formation was confirmed
by the chemical shifts (H-4 of unit B at δ 3.68 for both com-
pounds 3 and 4). In both cases, we have observed the formation
of only the desired thioester without competing formation of
amide or ester linkages.
during coupling with an appropriate AE nitrone. This group
should be removable without deprotection of the ester linkage
between the CD and B rings. We chose to protect hydroxy
groups of sugar rings B and D with the acetate protecting
group. The acetate group should be removed selectively using
the guanidine–guanidinium nitrate reagent.33 First, known
alcohol 4124b was converted into its corresponding sodium salt
(NaH, THF, rt, 1 h) then coupled with acid chloride 40 to give
ester 4216 in 67% yield (Scheme 8). Removal of both triethylsilyl
Our approach to the synthesis of hemiacetal 7,16 which is an
I
intermediate for the synthesis of the novel calicheamicin γ1
analogue 6, employed thiorhamnoside 348f and the phenol 358h
as starting materials. In this part, we wished to develop a
new approach to the synthesis of 4-rhamnosyloxy-substituted
benzoic acid 29.8h Glycosylation of thioglycoside 34 with
phenol 35 in presence of N-iodosuccinimide29 (NIS) and a
catalytic amount of trimethylsilyl trifluoromethanesulfonate as
promoter produced the expected aryl α-L-rhamnoside 36 in
68% yield (Scheme 7). The stereochemistry of the newly formed
Scheme 8 Reagents, conditions and yields: (i) NaH, THF, 1 h; then
40, 0 ЊC, 30 min, 67%; (ii) 1% HCl in dry MeOH, rt, 15 min, 75%;
(iii) Ac2O, pyridine, rt, 3 h, 83%; (iv) water–AcOH 2:1, reflux, 2 h, 73%.
and tetrahydropyran-2-yl groups was achieved using acidic
conditions (1% HCl in dry methanol) and subsequent acetyl-
ation of the resulting triol 43 yielded oligosaccharide 44 in 62%
over the two steps. Final acidic hydrolysis of methyl α-glycoside
44 afforded the desired hemiacetal 7 in 73% yield and as a 1:4
mixture of α and β anomers. In future work, we plan to couple
7 with a nitrone along lines similar to those described herein, to
complete the synthesis of novel calicheamicin γ1 I analogue 6.
We have undertaken some preliminary studies to evaluate the
DNA binding properties of oligosaccharides 3 and 4. The circu-
lar dichroism spectrum of oligosaccharide 4 was recorded in the
presence of oligonucleotide 5Ј-d(CCCGGTCCTAAG) using
conditions described by Ellestad.34 Although we observed some
small effects which indicated that oligosaccharide 4 was binding
the double-strand DNA, problems with the solubility of these
analogues precluded a more detailed study.
In summary, we have described the synthesis of complex
calicheamicin γ1 I and esperamicin A1B oligosaccharides 3–5, in
good yield and good stereoselectivity, which are potential DNA
ligands. Studies to evaluate the DNA-binding properties of
these oligosaccharides are ongoing. We have also reported the
synthesis of hemiacetal 7, which is a precursor to the synthesis
Scheme 7 Reagents, conditions and yields: (i) NIS, TMSOTf, CH2Cl2,
4 Å molecular sieves, 0 ЊC, 2 h, 68%; (ii) TBAF, THF, rt, 4 h, 75%;
(iii) RuCl3, NaIO4, CCl4–CH3CN–water 1:1:3, rt, 1 h, 60%; (iv) H2O2,
LiOH, THF–water 3:1, rt, 2 h, 79%; (v) Et3SiOTf, pyridine, DMAP,
CH2Cl2, rt, 1 h, 80%; (vi) (COCl)2, CH2Cl2, rt, 1 h.
I
of calicheamicin γ1 analogue 6. Continuing studies directed
α-glycosidic bond was confirmed by a small vicinal coupling
constant (J1,2 = 2.0 Hz) for the anomeric hydrogen to the neigh-
bouring H-2 hydrogen. No aryl β-L-rhamnoside was observed
in this case. Treatment of this aryl α-L-rhamnoside with tetra-n-
butylammonium fluoride (TBAF) and subsequent Sharpless
oxidation30 of the resulting primary alcohol 37 gave acid 38.
Smooth removal of acetate groups was performed in the
presence of lithium hydroxide and hydrogen peroxide31 to yield
known aryl rhamnoside 29.8h Silylation of both hydroxy groups
[triethylsilyl trifluoromethanesulfonate, pyridine, 4-(dimethyl-
amino)pyridine (DMAP)] and treatment of the resulting
carboxylic acid 398f,32 with oxalyl dichloride furnished acid
chloride 40.8f
towards the total synthesis of analogue 6 are in progress.
Experimental
General
Reactions requiring anhydrous conditions were performed
using oven-dried glassware and conducted under a positive
pressure of argon. Anhydrous solvents were prepared with
standard protocols and were freshly distilled. All reactions were
monitored by TLC on 0.2 mm Merck silica gel plates (60F254
)
using UV light, ethanol–sulfuric acid (10:1) solution or 2%
phosphomolybdic acid solution as spot-visualisation agent.
Flash column chromatography was performed on Merck silica
gel 60 (0.036–0.063 mm). Optical rotations were determined at
The completion of the synthesis of hemiacetal 7 involved the
introduction of a participating group at the 3-position8h,23 of
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20–25 ЊC using a Perkin-Elmer polarimeter (model 41), and
specific optical rotation-values [α]D are given in 10Ϫ1 deg cm2
g
(C-2), 18.8 (C-6); m/z 404 (M ϩ NH4)ϩ (Found: C, 64.89; H
5.40. C21H22O5S requires C, 65.27; H, 5.74%).
Ϫ1. NMR spectra were recorded on a Bruker AVANCE DPX
250 spectrometer with SiMe4 as internal reference. J-Values are
given in Hz. IR spectra were recorded on a Perkin-Elmer TF
PARAGON 1000 PC spectrophotometer. Mass spectra were
recorded under CIϩ conditions using ammonia on a Ribermag
R10-10 spectrometer at the Centre de Mesures Physiques,
Orléans University or under ion-spray conditions on a Perkin-
Elmer SCIEX API 300 spectrometer at the Institut de Chimie
Organique et Analytique, Orléans University. Accurate masses
were recorded under Fast Atom Bombardment (FAB) accurate
mass method using a NOBA matrix on Micromass Autospec
high-resolution instrument or under positive-ion electrospray
on a Finnigan MAT 900 XLT high-resolution mass spectro-
meter. Elemental analyses were carried out at the Service
Central de Microanalyses du CNRS at Vernaison, France.
3-O,4-S-Dibenzoyl-2,6-dideoxy-4-thio-ꢁ- and -ꢂ-D-ribo-hexo-
pyranose 12
A solution of compound 11 (140 mg, 0.36 mmol) in a mixture
of water (4 mL) and AcOH (2 mL) was heated at reflux for 2 h.
The solution was evaporated, then final traces of solvent were
coevaporated (3×) with toluene. Column chromatography
(heptane–ethyl acetate 2:1) provided hemiacetal 12 (115 mg,
85%) as a colorless, oily, 1:3 mixture of the α- and β-isomers.
For β-isomer: δH (250 MHz; CDCl3) 1.41 (3H, d, J5,6 6.0, H3-6),
1.97 (1H, ddd, J2eq,2ax 14.0, J2ax,3 3.0, J2ax,1 9.5, H-2ax), 2.44 (1H,
ddd, J2eq,1 2.0, J2eq,3 3.0, J2eq,2ax 14.0, H-2eq), 4.00 (1H, dd, J5,4
10.8, J4,3 3.0, H-4), 4.24 (1H, dq, J5,6 6.0, J5,4 10.8, H-5), 5.23
(1H, dd, J1,2ax 9.5, J1,2eq 2.0, H-1), 5.61 (1H, m, J3,4 = J3,2ax
=
J3,2eq = 3.0, H-3), 7.40–7.66 (6H, m, ArH), 7.97 (2H, m, ArH),
8.20 (2H, m, ArH). For α-isomer: δH (250 MHz; CDCl3) 1.38
(3H, d, J5,6 6.0, H3-6), 2.25 (1H, ddd, J2eq,2ax 15.0, J2ax,3 3.0, J2ax,1
4.0, H-2ax), 2.36 (1H, ddd, J2eq,1 1.2, J2eq,3 3.0, J2eq,2ax 15.0,
H-2eq), 4.07 (1H, dd, J5,4 10.5, J4,3 3.0, H-4), 4.63 (1H, dq, J5,6
6.0, J5,4 10.5, H-5), 5.40 (1H, d, J1,2 4.0, H-1), 5.57 (1H, m,
J3,4 = J3,2ax = J3,2eq = 3.0, H-3), 7.40–7.66 (6H, m, ArH), 7.97
(2H, m, ArH), 8.20 (2H, m, ArH); m/z 390 (M ϩ NH4)ϩ, 355
(M Ϫ OH).
Methyl 4-S-benzoyl-2,6-dideoxy-4-thio-3-O-(2,2,2-trifluoro-
ethylsulfonyl)-ꢁ-D-arabino-hexopyranoside 9
To a stirred solution of alcohol 817 (50 mg, 0.18 mmol) and
pyridine (43 µL, 0.53 mmol) in dry CH2Cl2 (1 mL) at 0 ЊC
was added 2,2,2-trifluoroethanesulfonyl chloride (26 µL, 0.23
mmol). The solution was stirred at room temperature for 2 h
and then diluted with water. The organic layer was extracted,
dried over MgSO4, filtered and the solvent was removed in
vacuo. The yellow solid 9 (65 mg) was used immediately in the
next step.
3-O,4-S-Dibenzoyl-2,6-dideoxy-4-thio-ꢁ- and -ꢂ-D-ribo-hexo-
pyranosyl trichloroacetimidate 13
To a stirred solution of hemiacetal 12 (39 mg, 0.10 mmol) in dry
CH2Cl2 (1.5 mL) at room temperature were added trichloro-
acetonitrile (105 µL, 1.05 mmol) and DBU (8 µL, 0.05 mmol).
The mixture was stirred for 1 h and subsequent filtration on
basic alumina HF254 (CH2Cl2) provided imidate 13 (49 mg,
quantitative) as a yellow solid.
Methyl 3-O-benzoyl-2,6-dideoxy-4-thio-ꢁ-D-ribo-hexopyrano-
side 1017
A solution of 9 (65 mg, 0.15 mmol) in 1,2-dichloroethane (3.5
mL), pyridine (25 µL, 0.30 mmol) and water (300 µL) was
heated at reflux for 1 h. The solvent was removed under reduced
pressure, finally by coevaporation with toluene. Column
chromatography (heptane–ethyl acetate 4:1) provided thiol 10
(34 mg, 68% from compound 8) as a colorless oil; νmax (thin
film)/cmϪ1 2576 (SH), 1717 (C᎐O); δ (250 MHz; CDCl3) 1.42
Methyl 2-O-(4Ј-bromobutyl)-4,6-dideoxy-4-hydroxyimino-3-O,-
4-(hydroxyimino O)-isopropylidene-ꢁ-D-xylo-hexopyranoside 15
᎐
H
To a stirred solution of alcohol 1413 (511 mg, 2.21 mmol) in dry
DMF (35 mL) at 0 ЊC were added 1,4-dibromobutane (528 µL,
4.42 mmol) and sodium hydride (60% dispersion in oil washed
with heptane; 69 mg, 2.87 mmol). The mixture was stirred for
3 h at 0 ЊC and treated with tert-butyl alcohol. The solution was
diluted with water and extracted with CH2Cl2. The organic
layer was dried over MgSO4, filtered and the solvent removed
in vacuo. Column chromatography (heptane–ethyl acetate 4:1
containing 0.2% Et3N) provided oxime 15 (494 mg, 61%) as a
colorless oil; [α]D ϩ74 (c 1.09, CHCl3); δH (250 MHz; CDCl3)
1.40 (3H, d, J5,6 6.0, H3-6), 1.42 and 1.50 (2 × 3H, 2s, CMe2),
1.74 (2H, m, J3Ј,2Ј 7.0, H2-3Ј), 1.97 (2H, m, H2-2Ј), 3.45 (2H, t,
J3Ј,4Ј 7.0, H2-4Ј), 3.48 (3H, s, OCH3), 3.51 (1H, dd, J1,2 3.5, J 2,3
9.5, H-2), 3.67 (1H, dt, J1Ј,2Ј 7.0, J1Ј,1Ј 10.0, H-1Ј), 3.75 (1H, dt,
H-1Ј), 4.44 (1H, q, J5,6 6.0, H-5), 4.52 (1H, d, J2,3 9.5, H-3), 4.82
(1H, d, J1,2 3.5, H-1); δC (62.9 MHz; CDCl3) 154.3 (C-4), 99.2
(CMe2), 98.0 (C-1), 79.9 (C-2), 71.0 (C-1Ј), 66.0 (C-3), 63.7
(C-5), 55.8 (OCH3), 33.5 (C-4Ј), 29.3, 28.4 (C-3Ј, -2Ј), 26.8
(CMe2), 20.7 (CMe2), 14.5 (C-6); m/z 366 and 368 (MHϩ)
(Found: C, 46.06; H, 6.71; N, 3.75. C14H24BrNO5 requires C,
45.91; H, 6.60; N, 3.82%).
(3H, d, J5,6 6.5, H3-6), 1.64 (1H, d, J4,SH 10.0, SH), 2.06 (1H,
ddd, J2eq,2ax 15.0, J2ax,3 3.0, J2ax,1 4.0, H-2ax), 2.33 (1H, ddd, J2eq,1
1.0, J2eq,3 3.0, J2eq,2ax 15.0, H-2eq), 2.84 (1H, td, J5,4
=
J4,SH = 10.0, J4,3 3.0, H-4), 3.35 (3H, s, OCH3), 4.19 (1H, dq, J5,6
6.5, J5,4 10.0, H-5), 4.77 (1H, d, J1,2 4.0, H-1), 5.34 (1H, m,
J3,4 = J3,2ax = J3,2eq = 3.0, H-3), 7.40–7.60 (3H, m, ArH), 8.10
(2H, m, ArH).
Methyl 3-O,4-S-dibenzoyl-2,6-dideoxy-4-thio-ꢁ-D-ribo-hexo-
pyranoside 11
Benzoyl chloride (490 µL, 4.23 mmol) was added dropwise to a
stirred solution of thiol 10 (597 mg, 2.11 mmol) in dry pyridine
(3 mL) at 0 ЊC. The mixture was stirred for 5 h at room temper-
ature and diluted with CH2Cl2. The organic layer was washed
successively with water, saturated aq. NaHCO3, then brine,
and dried over MgSO4. The filtrate was concentrated in vacuo to
give a yellow oil. Column chromatography (toluene–acetone
50:1) provided compound 11 (715 mg, 88%) as a colorless oil;
[α]D ϩ308 (c 1.43, CHCl3); νmax (thin film)/cmϪ1 1720 (O–C᎐O),
᎐
1670 (S–C᎐O); δ (250 MHz; CDCl3) 1.40 (3H, d, J5,6 6.5, H3-
᎐
H
6), 2.23 (1H, ddd, J2eq,2ax 15.0, J2ax,3 3.0, J2ax,1 4.0, H-2ax), 2.38
(1H, ddd, J2eq,1 1.0, J2eq,3 3.0, J2eq,2ax 15.0, H-2eq), 3.35 (3H, s,
OCH3), 4.11 (1H, dd, J5,4 10.5, J4,3 3.0, H-4), 4.48 (1H, dq, J5,6
6.5, J5,4 10.5, H-5), 4.97 (1H, d, J1,2 4.0, H-1), 5.45 (1H, m,
J3,4 = J3,2ax = J3,2eq = 3.0, H-3), 7.40–7.66 (6H, m, ArH), 7.97
(2H, m, ArH), 8.20 (2H, m, ArH); δC (62.9 MHz; CDCl3) 190.0
Methyl 4,6-dideoxy-2-O-[4Ј-(ethylamino)-butyl]-4-hydroxy-
imino-3-O,4-(hydroxyimino O)-isopropylidene-ꢁ-D-xylo-hexo-
pyranoside 16
A solution of oxime 15 (480 mg, 1.31 mmol) in DMF (3 mL)
was added dropwise to a stirred solution of ethylamine (11 mL)
at 0 ЊC. The mixture was stirred for 10 h at room temperature
then evaporated to dryness. Column chromatography (CH2Cl2–
MeOH 8:1 containing 2% of 32% aq. ammonia) provided a
pale yellow oil. This oil was dissolved in CH2Cl2 (5 mL) and the
(SC᎐O), 165.7 (OC᎐O), 136.5 (CH arom), 133.6 (C arom),
᎐
᎐
132.9 (CH arom), 130.5 (CH arom), 130.1 (CH arom), 129.8
(CH arom), 129.0 (CH arom), 128.6 (CH arom), 128.3 (CH
arom), 128.2 (CH arom), 127.4 (CH arom), 125.2 (CH arom),
97.4 (C-1), 69.9 (C-3), 63.5 (C-5), 55.2 (OCH3), 47.8 (C-4), 34.0
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
309

View Article Online
solution was saturated with gaseous ammonia at room tem-
perature for 15 min. The resulting solution was filtered from a
white solid on Celite and the solvent removed to afford com-
pound 16 (433 mg) as a colorless oil; δH (250 MHz; CDCl3) 1.10
(3H, t, J5Ј,6Ј 7.0, H3-6Ј), 1.32 (3H, d, J5,6 6.5, H3-6), 1.34 and 1.42
(2 × 3H, 2s, CMe2), 1.58 (4H, m, H2-2Ј, -3Ј), 2.64 (2H, m,
H2-4Ј), 2.66 (2H, m, H2-5Ј), 3.41 (3H, s, OCH3), 3.45 (1H, dd,
J1,2 3.5, J2,3 9.5, H-2), 3.56 (1H, m, H-1Ј), 3.70 (1H, m, H-1Ј),
4.36 (1H, m, J5,6 6.5, H-5), 4.44 (1H, d, J2,3 9.5, H-3), 4.76 (1H,
d, J1,2 3.5, H-1), 6.00 (1H, br s, NH); δC (62.9 MHz; CDCl3)
154.2 (C-4), 99.1 (CMe2), 97.9 (C-1), 79.8 (C-2), 71.8 (C-1Ј),
66.0 (C-3), 63.5 (C-5), 55.6 (OCH3), 48.9 (C-4Ј), 43.7 (C-5Ј),
27.5 (C-3Ј), 26.7 (CMe2), 26.5 (C-2Ј), 20.6 (CMe2), 14.6, 14.4
(C-6, -6Ј); m/z 331 (MH)ϩ.
71.1, 70.7 (C-4, -1Ј), 66.5 (CH2 Fmoc), 64.4, 63.0 (C-5, -3), 55.2
(OCH3), 47.5 (CH Fmoc), 46.8 (C-4Ј), 42.3 (C-5Ј), 27.2 (CMe2,
C-3Ј), 24.8 (C-2Ј), 19.9 (CMe2), 17.1 (C-6), 13.7 (C-6Ј); m/z 555
(MH)ϩ (Found: C, 67.12; H, 7.92; N, 4.77. C31H42N2O7 requires
C, 67.13; H, 7.63; N, 5.05%).
Methyl 4,6-dideoxy-2-O-[4Ј-(ethylamino)-butyl]-4-hydroxy-
amino-3-O,4-(hydroxyamino O)-isopropylidene-ꢁ-D-gluco-
pyranoside 19
The hydroxylamine 18 (22 mg, 40 µmol) was treated with
morpholine (0.5 mL) at room temperature. After 2 h, the
solvent was removed and the residue was subjected to column
chromatography (CH2Cl2–MeOH 6:1 containing 2% Et3N) to
give a colorless oil. This oil was dissolved in CH2Cl2 (0.5 mL),
and the solution was saturated with gaseous ammonia and
stirred at room temperature for 15 min. The resulting solution
was filtered from a white solid on Celite and the solvent was
removed to afford amine 19 (7 mg, 53%) as a colorless oil; [α]D
ϩ42 (c 0.65, CHCl3); δH (250 MHz; CDCl3) 1.11 (3H, t, J5Ј,6Ј 7.0,
H3-6Ј), 1.16 (3H, d, J5,6 6.5, H3-6), 1.37 and 1.60 (2 × 3H, 2s,
CMe2), 1.59 (4H, m, H2-2Ј, -3Ј), 2.62 (2H, t, J4Ј,3Ј 7.0, H2-4Ј),
2.65 (2H, q, J5Ј,6Ј 7.0, H2-5Ј), 2.85 (1H, dt, J3,4 = J4,5 = 10.0, J4,NH
4.0, H-4), 3.41 (3H, s, OCH3), 3.43 (1H, dd, J1,2 3.5, J2,3 10.0,
H-2), 3.57 (1H, dt, J1Ј,1Ј 10.0, J1Ј,2Ј 6.0, H-1Ј), 3.70 (1H, dt, J1Ј,1Ј
10.0, J1Ј,2Ј 6.0, H-1Ј), 3.71 (1H, dq, J5,6 6.5, J4,5 10.0, H-5), 4.18
(1H, dd, J2,3 = J3,4 = 10.0, H-3), 4.76 (1H, d, J1,2 3.5, H-1), 5.15
(1H, s, JNH,4 4.0, NH); δC (62.9 MHz; CDCl3) 101.4 (CMe2),
98.9 (C-1), 77.6 (C-2), 71.4, 70.7 (C-1Ј, -4), 64.3, 63.0 (C-5,
-3), 55.2 (OCH3), 49.5 (C-4Ј), 44.0 (C-5Ј), 27.8, 27.7 (CMe2,
C-3Ј), 26.5 (C-2Ј), 19.9 (CMe2), 17.1 (C-6), 15.2 (C-6Ј); m/z 333
(MH)ϩ.
Methyl 4,6-dideoxy-2-O-{4Ј-[N-ethyl-N-(fluoren-9-ylmethoxy-
carbonyl)amino]butyl}-4-hydroxyimino-3-O,4-(hydroxyimino
O)-isopropylidene-ꢁ-D-xylo-hexopyranoside 17
To a stirred solution of amine 16 (433 mg, 1.31 mmol) in THF–
water (2.5:1; 3.7 mL) at 0 ЊC were added K2CO3 (363 mg, 2.62
mmol) and fluoren-9-ylmethyl chloroformate (510 mg, 1.97
mmol) over a period of 30 min. The mixture was stirred for 45
min at 0 ЊC and diluted with CH2Cl2. The organic layer was
dried over MgSO4, filtered and the solvent removed in vacuo.
Column chromatography (heptane–ethyl acetate 4:1 contain-
ing 0.2% Et3N) provided tertiary amine 17 (550 mg, 76% from
compound 15) as a colorless oil; [α]D ϩ42 (c 1.04, CHCl3);
νmax (thin film)/cmϪ1 1700 (C᎐O); δ (250 MHz; CDCl3) 0.90–
᎐
H
1.10 (3H, m, H3-6Ј), 1.39 (3H, d, J5,6 6.5, H3-6), 1.40 and 1.50
(2 × 3H, 2s, CMe2), 1.40–1.60 (4H, m, H2-2Ј, -3Ј), 3.00 (1H, br s,
H-4Ј), 3.25 (3H, m, H2-5Ј, H-4Ј), 3.48 (3H, s, OCH3), 3.58 (1H,
br s, H-2), 3.60 (1H, br s, H-1Ј), 3.70 (1H, br s, H-1Ј), 4.22 (1H,
m, H Fmoc), 4.50 (4H, m, H-3, -5, CH2 Fmoc), 4.80 (1H, br s,
H-1), 7.30–7.44 (4H, m, Fmoc), 7.60 (2H, d, Fmoc), 7.78 (2H,
d, Fmoc); δC (62.9 MHz; CDCl3) 154.3 (C-4), 144.1 (C arom),
141.3 (C arom), 127.5 (CH arom), 126.9 (CH arom), 124.7 (CH
arom), 119.8 (CH arom), 99.1 (CMe2), 98.0 (C-1), 79.8 (C-2),
71.6 (C-1Ј), 66.0 (C-3), 63.6 (C-5), 55.7 (OCH3), 47.4 (CH
Fmoc), 46.5 (C-4Ј), 42.2 (C-5Ј), 27.0, 26.8 (C-2Ј, -3Ј, CMe2),
20.6 (CMe2), 14.5 (C-6), 13.8 (C-6Ј); m/z 553 (MH)ϩ (Found: C,
67.05; H, 7.43; N, 4.87. C31H40N2O7 requires C, 67.37; H, 7.29;
N, 5.07%).
Methyl 4,6-dideoxy-2-O-{4Ј-[N-ethyl-N-(fluoren-9-ylmethoxy-
carbonyl)amino]butyl}-4-(4-methoxybenzylideneamino)-ꢁ-D-
glucopyranoside 4-N-oxide 20
A solution 0.3 M HCl in MeOH–water (3:1; 4 mL) was added
to the hydroxylamine 18 (56 mg, 100 µmol) at room temper-
ature. The mixture was stirred for 90 min, then neutralised with
solid NaHCO3 and diluted with CH2Cl2. The organic layer was
dried over MgSO4, filtered, and the solvent removed in vacuo to
give a white solid. This solid was taken up in dry toluene (3 mL)
and treated with p-methoxybenzaldehyde (16 µL, 130 µmol).
The mixture was refluxed for 1 h, then evaporated to dry-
ness. Column chromatography (CH2Cl2–acetone 4:1) provided
nitrone 20 (52 mg, 82% from compound 18) as a colorless oil;
[α]D ϩ14 (c 0.73, CHCl3); νmax (thin film)/cmϪ1 3417 (OH), 1689
Methyl 4,6-dideoxy-2-O-{4Ј-[N-ethyl-N-(fluoren-9-ylmethoxy-
carbonyl)amino]butyl}-4-hydroxyamino-3-O,4-(hydroxyamino
O)-isopropylidene-ꢁ-D-glucopyranoside 18
A solution of compound 17 (564 mg, 1.02 mmol) and sodium
cyanoborohydride (1 M in THF; 20.4 mL, 20.4 mmol) in dry
CH2Cl2 (16 mL) at Ϫ30 ЊC was treated with BF3–Et2O (501 µL,
4.08 mmol) dropwise over a period of 3 h. After a further 1 h
at Ϫ30 ЊC, the mixture was neutralised with a solution of
ammonia–aq. ammonium chloride (1:1; 2 mL), allowed to
warm to room temperature, and diluted with CH2Cl2. The
organic phase was washed with brine, then dried over MgSO4.
The solvent was removed in vacuo and column chromatography
(heptane–ethyl acetate 2:1) provided the hydroxylamine 18 (490
mg, 86%) as a colorless oil; [α]D ϩ25 (c 1.06, CHCl3); νmax (thin
(C᎐O); δH (250 MHz; CDCl3) 1.00 (3H, m, H3-6Ј), 1.24 (3H, d,
᎐
J5,6 6.5, H3-6), 1.32–1.70 (4H, m, H2-2Ј), 3.10–3.42 (6H, m,
H2-5Ј, -4Ј, H-2, -4), 3.42 (3H, s, OCH3), 3.56 (1H, br s, H-1Ј),
3.74 (1H, br s, H-1Ј), 3.84 (3H, s, OCH3), 4.21 (1H, m, H
Fmoc), 4.46 (3H, m, H-5, CH2 Fmoc), 4.66 (1H, td, J3,2 = J3,4
=
9.5, J3,OH 3.5, H-3), 4.82 (1H, br s, H-1), 6.92 (2H, d, J 9.0,
ArH), 7.27–7.43 (5H, m, ArH, CH᎐N), 7.56 (2H, d, ArH), 7.75
᎐
(2H, d, ArH), 8.24 (2H, d, J 9.0, ArH); δC (62.9 MHz; CDCl3)
161.0 (C arom), 156.0 (NC᎐O), 144.1 (C arom), 141.3 (C arom),
᎐
135.7 (CH᎐N), 130.8 (CH arom), 127.5 (CH arom), 126.9 (CH
᎐
arom), 124.8 (CH arom), 123.2 (C arom), 119.8 (CH arom),
113.8 (CH arom), 97.2 (C-1), 81.6, 80.7 (C-2, -4), 70.5 (C-1Ј),
67.0, 66.9 (C-3, CH2 Fmoc), 63.9 (C-5), 55.3 (OCH3), 55.1
(OCH3), 47.3 (CH Fmoc), 46.5 (C-4Ј), 42.0 (C-5Ј), 27.0 (C-3Ј),
25.0 (C-2Ј), 17.4 (C-6), 13.8 (C-6Ј); m/z 633 (MH)ϩ (Found: C,
68.33; H, 7.08; N, 4.49. C36H44N2O8 requires C, 68.33; H, 7.01;
N, 4.43%).
film)/cmϪ1 3442 (NH), 1689 (C᎐O); δH (250 MHz; CDCl3) 1.02
᎐
(3H, m, H3-6Ј), 1.15 (3H, d, J5,6 6.5, H3-6), 1.36 and 1.58
(2 × 3H, 2s, CMe2), 1.36 (2H, m, H2-3Ј), 1.56 (2H, m, H2-2Ј),
2.84 (1H, dd, J3,4 = J4,5 = 10.0, H-4), 3.01 (1H, m, H-4Ј), 3.21
(3H, m, H2-5Ј, H-4Ј), 3.39 (3H, s, OCH3), 3.40 (1H, br s, H-2),
3.57 (1H, br s, H-1Ј), 3.67 (1H, br s, H-1Ј), 3.67 (1H, dq, J5,6 6.5,
J4,5 10.0, H-5), 4.16 (1H, dd, J2,3 = J3,4 = 10.0, H-3), 4.22 (1H, m,
H Fmoc), 4.46 (2H, m, CH2 Fmoc), 4.74 (1H, br s, H-1), 7.27–
7.43 (4H, m, Fmoc), 7.57 (2H, d, Fmoc), 7.76 (2H, d, Fmoc);
Methyl 4,6-dideoxy-2-O-[4Ј-(ethylamino)butyl]-4-(4-methoxy-
benzylideneamino)-ꢁ-D-glucopyranoside 4-N-oxide 21
δC (62.9 MHz; CDCl ) 156.0 (N᎐CO), 144.2 (C arom), 141.3
᎐
3
(C arom), 127.5 (CH arom), 126.9 (CH arom), 124.8 (CH
arom), 119.8 (CH arom), 101.4 (CMe2), 98.9 (C-1), 77.6 (C-2),
Deprotection of nitrone 20 (23 mg, 36 µmol) was carried out as
described for the preparation of 19 (column chromatography,
310
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315

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CH2Cl2–MeOH 8:1 containing 2% Et3N) and gave amine 21
(9 mg, 60%) as a white solid; [α]D ϩ35 (c 0.94, CHCl3);
νmax (KBr)/cmϪ1 3420 (NH); δH (250 MHz; CDCl3) 1.03 (3H, t,
J5Ј,6Ј 7.5, H3-6Ј), 1.24 (3H, d, J5,6 6.5, H3-6), 1.62–1.75 (4H, m,
H2-2Ј, -3Ј), 2.58 (2H, q, J5Ј,6Ј 7.5, H2-5Ј), 2.59 (1H, dt, J4Ј,3Ј 6.5,
J4Ј,4Ј 12.0, H-4Ј), 2.70 (1H, dt, J4Ј,3Ј 6.5, J4Ј,4Ј 12.0, H-4Ј), 3.31
(1H, dd, J1,2 3.5, J2,3 10.0, H-2), 3.40 (1H, dd, J3,4 = J4,5 = 10.0,
H-4), 3.43 (3H, s, OCH3), 3.58 (1H, dt, J1Ј,1Ј 10.0, J1Ј,2Ј 6.0,
H-1Ј), 3.80 (1H, dt, J1Ј,1Ј 10.0, J1Ј,2Ј 6.0, H-1Ј), 3.85 (3H, s,
OCH3), 4.45 (1H, dq, J5,6 6.5, J5,4 10.0, H-5), 4.56 (1H, dd,
J3,2 = J3,4 = 10.0, H-3), 4.79 (1H, d, J1,2 3.5, H-1), 6.90 (2H, d,
5.06 (1H, s, H aminoacetal), 5.47 (1H, m, H-3B), 6.53 (d, 2H,
Jo,m 8.5, 2H benzylidene), 7.20–7.78 (m, ArH).
Methyl 4-(3-O-benzoyl-2,6-dideoxy-4-S-methyl-4-thio-ꢂ-D-ribo-
hexopyranosyloxyamino)-4,6-dideoxy-2-O-{4Ј-[N-ethyl-N-
(fluoren-9-ylmethoxycarbonyl)amino]butyl}-ꢁ-D-glucopyrano-
side ꢂ-(and ꢁ)-25
A solution of DDQ (0.01 M in CH3CN–water 9:1; 295 µL, 2.95
µmol) was added over a period of 3 h to the oxazolidine 24
(53 mg, 59 µmol) at 0 ЊC. The solution was neutralised by addi-
tion of saturated aq. NaHCO3 and diluted with CH2Cl2. The
organic layer was extracted, dried over MgSO4, filtered and
evaporated to dryness. Column chromatography (heptane–ethyl
acetate 1:2) provided β-25 (22 mg, 48%) as a colorless oil; [α]D
ϩ35 (c 2.20, CHCl3); νmax (thin film)/cmϪ1 3451 (OH, NH), 1720
J 9.0, ArH), 7.35 (1H, s, CH᎐N), 8.25 (2H, d, J 9.0, ArH);
᎐
δC (62.9 MHz; CDCl ) 161.0 (C arom), 135.4 (CH᎐N), 130.7
᎐
3
(CH arom), 123.3 (C arom), 113.7 (CH arom), 97.6 (C-1), 82.0,
81.9 (C-2), 71.8 (C-1Ј), 66.5 (C-3), 63.8 (C-5), 55.3, 55.1
(2 × OCH3), 48.8 (C-4Ј), 43.9 (C-5Ј), 27.3 (C-3Ј), 26.8 (C-2Ј),
17.4 (C-6), 14.7 (C-6Ј); m/z 411 (MH)ϩ.
[Ph(C᎐O)O], 1690 [O(C᎐O)N]; δH (250 MHz; CDCl3) 0.99 (3H,
᎐
᎐
m, H3-6Ј), 1.32 (3H, d, J5,6 6.5, H3-6A), 1.44 (3H, d, J5,6 6.5,
H3-6B), 1.60 (4H, br s, H2-2Ј), 1.70 (1H, ddd, J2eq,2ax 14.0,
J2ax,3 3.0, J2ax,1 10.0, H-2axB), 2.10 (3H, s, SCH3), 2.12 (1H, ddd,
J2eq,2ax 14.0, J2eq,3 3.0, J2eq1 2.0, H-2eqB), 2.30 (1H, dd, J3,4 = J4,5
9.5, H-4A), 2.45 (1H, dd, J4,3 3.0, J4,5 10.5, H-4B), 2.98 (1H, m,
H-4Ј), 3.18 (3H, m, H-4Ј, H2-5Ј), 3.23 (1H, dd, J2,1 3.5, J2,3 9.5,
H-2A), 3.33 (3H, s, OCH3), 3.40–3.66 (2H, m, H2-1Ј), 3.87 (1H,
dq, J5,6 6.5, J5,4 9.5, H-5A), 4.02 (1H, dq, J5,6 6.5, J5,4 10.5,
H-5B), 4.16 (1H, dd, J3,4 = J2,3 = 9.5, H-3A), 4.18 (1H, m, H
Fmoc), 4.44 (2H, q, CH2 Fmoc), 4.71 (1H, br s, H-1A), 4.97
(1H, dd, J1,2eq 2.0, J1,2ax 10.0, H-1B), 5.59 (1H, m, H-3B), 6.65
(1H, br s, NH), 7.24–7.46 (6H, m, ArH), 7.55 (3H, m, ArH),
7.72 (2H, m, ArH), 8.00 (2H, dd, ArH); δC (62.9 MHz; CDCl3)
Methyl 4,6-dideoxy-4-(hydroxyamino O)-(3-O,4-S-dibenzoyl-
2,6-dideoxy-4-thio-ꢂ- and ꢁ-D-ribo-hexopyranosyl)2-O-{4Ј-[N-
ethyl-N-(fluoren-9-ylmethoxycarbonyl)amino]butyl}-4-hydroxy-
amino-3-O,4-(hydroxyamino N)-(4-methoxybenzylidene)-ꢁ-D-
glucopyranoside 23
A solution of nitrone 20 (30 mg, 47 µmol) in dry CH2Cl2 (3 mL)
was added to imidate 13 (49 mg, 95 µmol). The solution was
cooled to Ϫ20 ЊC and powdered 4 Å molecular sieves were
added. After 15 min, AgOTf (24 mg, 95 µmol) was added and
the solution was stirred for 2 h in the dark. The mixture was
filtered on Celite and the solvent removed in vacuo. Column
chromatography (heptane–ethyl acetate 3:2) provided 23 (43
mg, 92%) as a colorless oil and as a mixture of α and β anomers.
Major β-compound: δH (250 MHz; CDCl3) 1.00 (3H, m, H3-6Ј),
1.30–1.60 (4H, m, H2-2Ј, -3Ј), 1.32 (3H, d, J5,6 6.0, H3-6A), 1.54
(3H, d, J5,6 6.0, H3-6B), 1.85 (1H, m, J2eq,2ax 18.0, J2ax,3 2.5, J2ax,1
10.5, H-2axB), 2.04 (1H, m, H-2eqB), 2.75 (1H, dd,
J3,4 = J4,5 = 9.5, H-4A), 3.20–3.30 (5H, m, H2-4Ј, -5Ј H-2A), 3.34
(3H, s, OCH3), 3.41 (3H, s, OCH3), 3.55–3.70 (2H, m, H2-1Ј),
3.83 (1H, dd, J4,3 3.0, J4,5 11.0, H-4B), 3.95 (1H, dq, J5,6 6.0,
165.5 (OC᎐O), 156.0 (NC᎐O), 144.1 (C arom), 141.3 (C arom),
᎐
᎐
133.2 (C arom), 129.9 (C arom), 129.6 (CH arom), 128.5 (CH
arom), 127.5 (CH arom), 126.9 (CH arom), 124.8 (CH arom),
119.8 (CH arom), 100.0 (C-1B), 97.6 (C-1A), 81.0 (C-2A), 71.5
(C-1Ј), 70.4 (C-3B, -5B), 68.0 (C-4A), 66.4 (C-3A, CH2 Fmoc),
63.9 (C-5A), 55.1 (OCH3), 53.1 (C-4B), 47.4 (CH Fmoc), 46.7
(C-4Ј), 41.7 (C-5Ј), 34.7 (C-2B), 26.8 (C-3Ј), 24.6 (C-2Ј), 19.8
(C-6B), 17.9 (C-6A), 15.7 (SCH3), 13.7 (C-6Ј); m/z 779 (MH)ϩ.
Further elution (heptane–ethyl acetate 1:2) gave α-25 (8 mg,
17%) as a colorless oil; [α]D ϩ74 (c 0.78, CHCl3); δH (250 MHz;
CDCl3) 0.97 (3H, m, H3-6Ј), 1.13 (3H, d, J5,6 6.0, H3-6A), 1.41
(3H, d, J5,6 6.0, H3-6B), 1.60 (4H, br s, H2-2Ј, -3Ј), 1.99 (1H, m,
H-2axB), 2.12 (3H, s, SCH3), 2.30 (2H, m, H-4A, H-2eqB), 2.54
(1H, dd, J4,3 3.0, J4,5 10.5, H-4B), 2.97 (1H, br s, H-4Ј), 3.05–
3.25 (7H, m, H-4Ј, H2-5Ј, H-2A, OCH3), 3.49 (1H, br s, H-1Ј),
3.66 (2H, m, H-5A, H-1Ј), 3.91 (1H, dd, J3,4 = J2,3 = 10.0, H-
3A), 4.19 (1H, dd, H Fmoc), 4.28 (1H, m, H-5B), 4.43 (2H, m,
CH2 Fmoc), 4.67 (1H, br s, H-1A), 5.06 (1H, dd, J1,2ax 4.5, J1,2eq
≈1–2, H-1B), 5.39 (1H, m, J3,4 = J3,2ax = 3.0, H-3B), 6.30 (1H, br
s, NH), 7.26–7.56 (12H, m, Fmoc, ArH), 7.72 (2H, dd, Fmoc),
8.05 (2H, dd, OBz).
J5,4 9.5, H-5A), 4.21 (1H, m, H-5B), 4.33 (1H, dd, J2,3
=
J3,4 = 9.5, H-3A), 4.43 (3H, m, H Fmoc, CH2 Fmoc), 4.62 (1H,
dd, J1,2eq 2.0, J1,2ax 10.5, H-1B), 4.83 (1H, br s, H-1A), 5.10
(1H, s, H aminoacetal), 5.45 (1H, m, H-3B), 6.55 (2H, d, Jo,m
8.5, 2H benzylidene), 7.25–7.90 (m, ArH).
Methyl 4-(hydroxyamino O)-(3-O-benzoyl-2,6-dideoxy-4-S-
methyl-4-thio-ꢂ- and ꢁ-D-ribo-hexopyranosyl)-4,6-dideoxy-2-O-
{4Ј-[N-ethyl-N-(fluoren-9-ylmethoxycarbonyl)amino]-butyl}-
3-O,4-(hydroxyamino N)-(4-methoxybenzylidene)-ꢁ-D-gluco-
pyranoside 24
A solution of nitrone 20 (55 mg, 87 µmol) in dry CH2Cl2 (5 mL)
was added to imidate 228i (75 mg, 0.16 mmol). The solution was
cooled to Ϫ20 ЊC and powdered 4 Å molecular sieves were
added. After 15 min at Ϫ20 ЊC, the mixture was treated with
AgOTf (45 mg, 174 µmol) and the solution was stirred for 2 h in
the dark at room temperature. The mixture was filtered on
Celite and the solvent removed in vacuo. Column chromato-
graphy (heptane–ethyl acetate 3:1) provided compound 24
(59 mg, 76%) as a white foam (mixture of α and β anomers).
Major β-compound: δH (250 MHz; CDCl3) 0.92 (3H, m, H3-6Ј),
1.30–1.63 (4H, m, H2-2Ј, -3Ј), 1.35 (3H, d, J5,6 6.0, H3-6A), 1.49
(3H, d, J5,6 6.0, H3-6B), 1.62 (1H, m, J2eq,2ax 18.0, J2ax,3 2.5, J 2ax,1
10.5, H-2axB), 1.96 (1H, m, H-2eqB), 2.04 (3H, s, SCH3), 2.35
(1H, dd, J4,3 3.0, J4,5 9.5, H-4B), 2.70 (1H, dd, J3,4 = J4,5 = 9.5,
H-4A), 2.90–3.23 (5H, m, H2-4Ј, -5Ј, H-2A), 3.30 (3H, s,
OCH3), 3.38 (3H, s, OCH3), 3.40–3.70 (2H, m, H2-1Ј), 3.92 (1H,
dq, J5,6 6.0, J5,4 9.5, H-5A), 4.18 (1H, m, H-5B), 4.29 (1H, dd,
J2,3 = J3,4 = 9.5, H-3A), 4.40 (3H, m, H Fmoc, CH2 Fmoc), 4.56
(1H, dd, J1,2eq 2.0, J1,2ax 10.5, H-1B), 4.79 (1H, br s, H-1A),
Methyl 4,6-dideoxy-4-(2,6-dideoxy-4-S-methyl-4-thio-ꢂ-D-ribo-
hexopyranosyloxyamino)-2-O-[4Ј-(ethylamino)butyl]-ꢁ-D-gluco-
pyranoside 5
To a stirred solution of β-25 (17 mg, 22 µmol) in dry MeOH
(0.8 mL) at room temperature was added solid potassium
carbonate (9 mg, 65 µmol). The mixture was stirred for 2 h, then
evaporated to dryness. Column chromatography (CH2Cl2–
MeOH 1:1 containing 1% of 32% aq. ammonia) provided a
colorless oil (12 mg). This oil was dissolved in CH2Cl2 (0.5 mL)
and the solution was saturated with gaseous ammonia at room
temperature for 15 min. The resulting solution was filtered from
a white solid on Celite and the solvent removed to afford amine
5 (9 mg, 91%) as a colorless oil; [α]D ϩ34 (c 0.86, CHCl3); νmax
(thin film)/cmϪ1 3417 (NH, OH); δH (250 MHz; CDCl3) 1.10
(3H, t, J5Ј,6Ј 7.0, H3-6Ј), 1.29 (3H, d, J5,6 6.5, H3-6B), 1.35 (3H, d,
J5,6 6.5, H3-6A), 1.49 (1H, ddd, J2eq,2ax 13.5, J2ax,3 3.0, J2ax,1 10.0,
H-2axB), 1.61 (4H, m, H2-2Ј), 2.07 (3H, s, SCH3), 2.08 (1H,
ddd, J2eq,2ax 13.5, J2eq,3 3.0, J2eq1 2.0, H-2eqB), 2.30 (1H, dt,
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
311

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J3,4 = J4,5 = 9.5, JNH,4 1.5, H-4A), 2.44 (1H, dd, J4,3 2.5, J4,5
10.0, H-4B), 2.63 (2H, q, J5Ј,6Ј 7.0, H2-5Ј), 2.64 (2H, t, J4Ј,3Ј 7.0,
H2-4Ј), 3.24 (1H, dd, J2,1 3.5, J2,3 9.5, H-2A), 3.36 (3H, s,
OCH3), 3.58 (1H, m, H-1Ј), 3.69 (1H, m, H-1Ј), 3.79 (1H, dq,
J5,6 6.5, J5,4 10.0, H-5B), 3.89 (1H, dq, J5,6 6.5, J5,4 9.5, H-5A),
4.05 (1H, m, H-3B), 4.14 (1H, dd, J3,4 = J2,3 = 9.5, H-3A), 4.72
(1H, d, J1,2 3.5, H-1A), 4.94 (1H, dd, J1,2eq 2.0, J1,2ax 10.0, H-1B),
6.54 (1H, d, JNH,4 1.5, NHO); δC (62.9 MHz; CDCl3) 99.6
(C-1B), 97.7 (C-1A), 81.6 (C-2A), 71.0 (C-1Ј), 68.8 (C-5B), 68.0
(C-4A), 66.0 (C-3A), 64.4, 64.2 (C-3B, -5A), 55.8 (C-4B), 55.1
(OCH3), 49.1 (C-4Ј), 43.9 (C-5Ј), 35.1 (C-2B), 27.7 (C-3Ј), 26.6
(C-2Ј), 20.0 (C-6B), 18.2 (C-6A), 14.6 (C-6Ј), 13.7 (SCH3); m/z
453 (MH)ϩ (Found: MHϩ, 453.2624. C20H41N2O7S requires m/z
453.2634).
(C arom), 133.6 (C arom), 133.3 (CH arom), 129.7 (CH arom),
129.6 (CH arom), 128.6 (CH arom), 128.5 (CH arom), 127.5
(CH arom), 127.4 (CH arom), 126.9 (CH arom), 125.8 (CH
arom), 124.8 (CH arom), 119.8 (CH arom), 100.1 (C-1B), 97.6
(C-1A), 81.0 (C-2A), 71.9 (C-1Ј), 70.7, 70.0 (C-3B, C-5B), 68.1
(C-4A), 66.4 (C-3A, CH2 Fmoc), 63.9 (C-5A), 55.1 (OCH3),
47.8, 47.4 (C-4B, CH Fmoc), 46.7 (C-4Ј), 42.2 (C-5Ј), 34.7
(C-2B), 26.8 (C-3Ј), 24.7 (C-2Ј), 19.0 (C-6B), 18.0 (C-6A), 13.7
(C-6Ј); m/z 869 (MH)ϩ (Found: C, 65.99; H, 6.32; N, 3.10.
C48H56N2O11S requires C, 66.34; H, 6.49; N, 3.22%).
Further elution (heptane–ethyl acetate 1:1) gave α-32 (8 mg,
13%) as a white foam; δH (250 MHz; CDCl3) 0.99 (3H, m,
H3-6Ј), 1.12 (3H, d, J5,6 6.0, H3-6A), 1.30–1.60 (4H, m, H2-2Ј,
-3Ј), 1.33 (3H, d, J5,6 6.0, H3-6B), 2.16 (1H, ddd, J2eq,2ax 15.0,
J2ax,3 3.0, J2ax,1 4.0, H-2axB), 2.35 (2H, ddd, H-4A, -2eqB), 2.97
(1H, br s, H-4Ј), 3.08–3.25 (7H, m, H-4Ј, H2-5Ј, H-2A, OCH3),
3.48 (1H, br s, H-1Ј), 3.66 (2H, m, H-5A, -1Ј), 3.90 (1H, dd,
J3,4 = J2,3 = 10.0, H-3A), 4.01 (1H, dd, J4,3 3.0, J4,5 10.5, H-4B),
4.18 (1H, t, H Fmoc), 4.43 (3H, m, CH2 Fmoc, H-5B), 4.67
(1H, br s, H-1A), 5.13 (1H, dd, J1,2ax 4.0, J1,2eq ≈ 1–2, H-1B),
5.32 (1H, m, J3,4 = J3,2ax = 3.0, H-3B), 6.65 (1H, br s, NH), 7.26–
7.56 (12H, m, Fmoc, ArH), 7.71 (2H, dd, Fmoc), 7.90 (2H, dd,
SBz), 8.06 (2H, dd, OBz).
Methyl 3-iodo-4,5,6-trimethoxy-2-methylbenzoate 27
Solid potassium carbonate (39 mg, 0.28 mmol) and dimethyl
sulfate (15 µL, 0.15 mmol) were added to a stirred solution of
the phenol 2627 (50 mg, 0.14 mmol) in acetone (1.3 mL). The
suspension was vigorously stirred for 24 h at room temper-
ature, then filtered on Celite and the solvent removed in vacuo.
Column chromatography (heptane–ethyl acetate 4:1) provided
title compound 27 (49 mg, 94%) as a colorless oil; δH (250 MHz;
CDCl3) 2.32 (3H, s, CH3), 3.84 (6H, s, OCH3, CO2CH3), 3.86
(3H, s, OCH3), 3.88 (3H, s, OCH3); δC (62.9 MHz; CDCl3) 167.7
Bis{methyl 4,6-dideoxy-2-O-[4Ј-(ethylamino)butyl]-4-(2,4,6-
trideoxy-ꢂ-D-ribo-hexopyranosyloxyamino)-ꢁ-D-glucopyranosid-
4-yl} disulfide 33
(C᎐O), 154.4 (C-4), 150.8 (C-6), 143.5 (C-5), 133.6 (C-2), 125.3
᎐
(C-1), 94.0 (C-3), 61.7 (OCH3), 60.9 (OCH3), 60.6 (OCH3), 52.5
(CO2CH3) 25.4 (ArCH3).
To a stirred solution of compound β-32 (41 mg, 47 µmol) in dry
MeOH (2 mL) at room temperature was added solid potassium
carbonate (26 mg, 189 µmol). The mixture was stirred for 2 h
and evaporated to dryness. Column chromatography (CH2Cl2–
MeOH 1:1 containing 1% of 32% aq. ammonia) provided a
colorless oil (20 mg). This oil was dissolved in CH2Cl2 (1 mL),
and the solution was saturated with gaseous ammonia and
stirred at room temperature for 15 min. The resulting solution
was filtered from a white solid on Celite and the solvent was
removed to afford disulfide 33 (15 mg, 72%) as a colorless oil;
[α]D ϩ52 (c 0.78, CHCl3); νmax (thin film)/cmϪ1 3458 (NH), 3276
(OH); δH (250 MHz; CDCl3) 1.07 (3H, t, J5Ј,6Ј 7.5, H3-6Ј), 1.29
(3H, d, J5,6 6.5, H3-6B), 1.35 (3H, d, J5,6 6.5, H3-6A), 1.59 (5H,
m, H2-2Ј, H-2axB), 2.02 (1H, ddd, J2eq,2ax 13.5, J2eq,3 3.5, J2eq,1
2.0, H-2eqB), 2.30 (1H, td, J4,NH 2.0, J3,4 = J4,5 = 10.0, H-4A),
2.60 (2H, m, H2-4Ј), 2.60 (2H, q, J5Ј,6Ј 7.5, H2-5Ј), 2.66 (1H, dd,
J4,3 2.5, J4,5 10.0, H-4B), 3.21 (1H, dd, J2,1 3.5, J2,3 10.0, H-2A),
3.36 (3H, s, OCH3), 3.55 (1H, m, H-1Ј), 3.68 (1H, m, H-1Ј), 3.73
(1H, dq, J5,6 6.5, J5,4 10.0, H-5B), 3.88 (1H, dq, J5,6 6.5, J5,4 10.0,
H-5A), 3.96 (1H, m, J3,4 = J3,2a = 2.5, J3,2e 3.5, H-3B), 4.12 (1H,
dd, J3,4 = J2,3 = 10.0, H-3A), 4.72 (1H, d, J2,1 3.5, H-1A), 4.95
(1H, dd, J1,2eq 2.0, J1,2ax 10.0, H-1B), 6.52 (1H, d, J4,NH 2.0,
NHO); δC (62.9 MHz; CDCl3) 99.6 (C-1B), 97.7 (C-1A), 81.6
(C-2A), 71.0 (C-1Ј), 68.0 (C-4A, -5B), 66.0 (C-3A), 65.4 (C-3B),
64.1 (C-5A), 59.3 (C-4B), 55.1 (OCH3), 49.2 (C-4Ј), 44.0 (C-5Ј),
36.1 (C-2B), 27.6 (C-3Ј), 26.7 (C-2Ј), 20.0 (C-6B), 18.2 (C-6A),
14.9 (C-6Ј); m/z 875 (MH)ϩ.
3-Iodo-4,5,6-trimethoxy-2-methylbenzoic acid 28
Compound 27 (49 mg, 0.13 mmol) in aq. 2.5 M NaOH (1 mL)
and methanol (0.5 mL) was heated at reflux for 6 h. The mixture
was then carefully poured into cold 5% aq. hydrochloric acid
and extracted with Et2O (3×). The organic phase was dried over
MgSO4, and concentrated. Column chromatography (CH2Cl2–
methanol 10:1) provided acid 28 (45 mg, 95%) as a white solid;
νmax (KBr)/cmϪ1 3422 (OH), 1580 (CO2H); δH (250 MHz;
CDCl3) 2.23 (3H, s, CH3), 3.76 (3H, s, OCH3), 3.77 (6H, s,
2 × OCH3); δC (62.9 MHz; CDCl3) 153.7 (C-4), 149.9 (C-6),
143.4 (C-5), 133.3 (C-2), 125.8 (C-1), 94.8 (C-3), 62.1 (OCH3),
60.9 (OCH3), 60.6 (OCH3), 25.5 (ArCH3); m/z 353 (MHϩ).
Methyl 4-(3-O,4-S-dibenzoyl-2,6-dideoxy-4-thio-ꢂ-D-ribo-
hexopyranosyloxyamino)-4,6-dideoxy-2-O-{4Ј-[N-ethyl-N-
(fluoren-9-ylmethoxycarbonyl)amino]butyl}-ꢁ-D-glucopyrano-
side ꢂ-(and ꢁ)-32
A solution of DDQ (0.01 M in CH3CN–water 9:1; 344 µL, 3.44
µmol) was added over a period of 1 h to 23 (68 mg, 69 µmol)
at 0 ЊC. The solution was then neutralised with saturated
aq. NaHCO3 and diluted with CH2Cl2. The organic layer
was extracted, dried over MgSO4, filtered and evaporated to
dryness. Column chromatography (heptane–ethyl acetate 1:1)
provided compound β-32 (45 mg, 75%) as a white foam; [α]D
ϩ92 (c 1.12, CHCl3); νmax (thin film)/cmϪ1 3474 (OH, NH), 1720
[Ph(C᎐O)O], 1694 [O(C᎐O)N], 1670 [Ph(C᎐O)S]; δ (250 MHz;
᎐
᎐
᎐
H
Methyl 4,6-dideoxy-4-[2,6-dideoxy-4S-(3-iodo-4,5,6-trimethoxy-
2-methylbenzoyl)-4-thio-ꢂ-D-ribo-hexopyranosyloxyamino]-2-O-
[4Ј-(ethylamino)butyl]-ꢁ-D-glucopyranoside 3
CDCl3) 1.02 (3H, m, H3-6Ј), 1.26 (3H, d, J5,6 6.5, H3-6A), 1.41
(3H, d, J5,6 6.5, H3-6B), 1.60 (4H, br s, H2-2Ј, -3Ј), 1.94 (1H,
ddd, J2eq,2ax 14.0, J2ax,3 3.0, J2ax,1 10.0, H-2axB), 2.22 (1H, ddd,
J2eq,2ax 14.0, J2eq,3 2.5, J2eq1 2.0, H-2eqB), 2.35 (1H, dd, J3,4 = J4,5
=
Preparation of mixed anhydride 30. Pyridine (10 µL, 119 µmol)
and phenyl dichlorophosphate (9 µL, 60 µmol) were added to
a stirred solution of acid 28 (14 mg, 40 µmol) in DME (195 µL)
at 0 ЊC. The mixture was stirred for 1 h at room temperature.
10.0, H-4A), 3.03 (2H, br s, H2-5Ј), 3.20 (br 2H, s, H2-4Ј), 3.26
(1H, dd, J2,1 3.5, J2,3 10.0, H-2A), 3.37 (3H, s, OCH3), 3.42–3.70
(2H, br s, H2-1Ј), 3.91 (1H, dq, J5,6 6.5, J5,4 10.0, H-5A), 3.95
(1H, dd, J4,3 3.0, J4,5 11.0, H-4B), 4.22 (3H, m, H-3A, -5B, H
Fmoc), 4.47 (2H, br s, CH2 Fmoc), 4.75 (1H, br s, H-1A), 5.05
(1H, dd, J1,2eq 2.0, J1,2ax 10.0, H-1B), 5.58 (1H, m, J3,4 = J3,2ax
3.0, J3,2eq 2.5, H-3B), 6.65 (1H, br s, NH), 7.27–7.62 (12H, m,
Fmoc, ArH), 7.75 (2H, dd, Fmoc), 7.91 (2H, dd, SBz), 8.04
Preparation of 3. Tri-n-butylphosphine (147 µL, 596 µmol)
was added to a stirred solution of disulfide 33 (12 mg, 13 µmol)
in DME (240 µL). The mixture was stirred for 1 h at room
temperature and then added to a stirred solution of the
above mixed anhydride 30 at 0 ЊC. The resulting mixture was
stirred for 24 h at room temperature, filtered through a short
=
(2H, dd, OBz); δC (62.9 MHz; CDCl ) 189.4 (SC᎐O), 165.1
᎐
3
(OC᎐O), 156.0 (NC᎐O), 144.1 (C arom), 141.3 (C arom), 136.4
᎐
᎐
312
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315

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pad of Celite, and the solvent was removed in vacuo. Column
chromatography (CH2Cl2–MeOH; 6:1 containing 1% of
32% aq. ammonia) gave a white solid (16 mg). This solid was
dissolved in CH2Cl2 (1 mL), and the solution was saturated
with ammonia and stirred at room temperature for 15 min. The
resulting solution was filtered on Celite and the solvent was
removed to afford amine 3 (11 mg, 53%) as a colorless oil; [α]D
ϩ28 (c 0.63, CHCl3); νmax (thin film)/cmϪ1 3432 (NH, OH), 1673
(C-3), 81.3 (C-2A), 80.8 (C-3D), 71.1 (C-1Ј), 70.3 (C-5D, -4D),
69.0 (C-5B), 68.1 (C-3B), 66.9 (C-2D), 66.4 (C-3A), 64.8
(C-5A), 61.6 (Ar-OCH3), 60.8 (Ar-OCH3), 57.1 (OCH3), 54.9
(OCH3), 51.9 (C-4B), 47.5 (C-4Ј), 42.9 (C-5Ј), 36.8 (C-2B), 29.7
(C-3Ј), 28.4 (C-2Ј), 25.3 (Ar-CH3), 19.2 (C-6B), 18.3 (C-6A),
17.5 (C-6D), 11.1 (C-6Ј). m/z 919 (MHϩ) (Found: MHϩ,
919.2764. C36H60IN2O15S requires m/z, 919.2759).
4-[(tert-Butyldiphenylsiloxy)methyl]-2-iodo-5,6-dimethoxy-3-
methylphenyl 2,4-di-O-acetyl-6-deoxy-3-O-methyl-ꢁ-L-manno-
pyranoside 36
[(C᎐O)S]; δ (250 MHz; CDCl3) 1.10 (3H, t, J5Ј,6Ј 7.5, H3-6Ј),
᎐
H
1.32 (3H, d, J5,6 6.5, H3-6A), 1.37 (3H, d, J5,6 6.5, H3-6B), 1.61
(4H, m, H2-2Ј, -3Ј), 1.75 (1H, m, J2eq,2ax 13.5, J2eq,3 3.0, J2eq,1
10.0, H-2axB), 1.98 (1H, ddd, J2eq,2ax 13.5, J2eq,3 3.0, J2eq,1 2.0,
H-2eqB), 2.31 (3H, s, CH3), 2.34 (1H, td, J3,4 = J4,5 = 9.5, J4,NH
2.0, H-4A), 2.63 (2H, q, J5Ј,6Ј 7.5, H2-5Ј), 2.64 (2H, m, H2-4Ј),
3.24 (1H, dd, J2,1 3.5, J2,3 9.5, H-2A), 3.38 (3H, s, OCH3), 3.56
(1H, m, H-1Ј), 3.68 (1H, m, H-1Ј), 3.68 (1H, dd, J4,3 2.5, J4,5
10.5, H-4B), 3.84 (3H, s, OCH3), 3.86 (3H, s, OCH3), 3.87 (3H,
s, OCH3), 3.89 (1H, dq, J5,6 6.5, J5,4 10.5, H-5B), 4.00 (1H, dq,
J5,6 6.5, J5,4 9.5 H-5A), 4.14 (1H, dd, J3,4 = J2,3 = 9.5, H-3A),
4.27 (1H, m, H-3B), 4.73 (1H, d, J2,1 3.5, H-1A), 5.02 (1H, dd,
J1,2eq 2.0, J1,2ax 10.0, H-1B), 6.60 (1H, d, J4,NH 2.0, NHO);
To a stirred solution of the phenol 358h (160 mg, 0.28 mmol),
sulfide 348f (111 mg, 0.31 mmol) and powdered 4 Å molecular
sieves in dry CH2Cl2 (6.5 mL) at 0 ЊC were successively added
NIS (83 mg, 0.37 mmol) and a solution of TMSOTf (1 M in
toluene, 29 µL, 29 µmol). The mixture was stirred for 2 h at
0 ЊC, neutralised with Et3N, filtered on Celite and the solvent
evaporated. Column chromatography (heptane–ethyl acetate
5:1) provided compound 36 (155 mg, 68%) as a colorless oil;
[α]D Ϫ14 (c 1.87, CHCl3); δH (250 MHz; CDCl3) 1.04 (9H, s,
But), 1.21 (3H, d, J5,6 6.0, H3-6), 2.13 (3H, s, OAc), 2.16 (3H,
s, OAc), 2.51 (3H, s, CH3), 3.44 (3H, s, OCH3), 3.63 (3H, s,
OCH3), 3.76 (3H, s, OCH3), 4.03 (1H, dd, J2,3 3.5, J3,4 10.0,
H-3), 4.41 (1H, dq, J4,5 10.0, J5,6 6.0, H-5), 4.76 (2H, s, CH2),
5.10 (1H, dd, J3,4 = J4,5 = 10.0, H-4), 5.56 (1H, d, J1,2 2.0, H-1),
5.79 (1H, dd, J1,2 2.0, J2,3 3.5, H-2), 7.34–7.44 (6H, m,
ArH), 7.66–7.71 (4H, m, ArH); δC (62.9 MHz; CDCl3) 170.2
δC (62.9 MHz; CDCl ) 192.0 (C᎐O), 150.3 (C-6), 143.6 (C-5),
᎐
3
132.9 (C-2), 130.3 (C-1), 99.6 (C-1B), 97.7 (C-1A), 94.3 (C-3),
81.8 (C-2A), 71.1 (C-1Ј), 68.7 (C-5B), 68.0 (C-4A, -3B), 66.0
(C-3A), 64.2 (C-5A), 61.8 (Ar-OCH3), 60.9 (Ar-OCH3), 60.6
(Ar-OCH3), 55.1 (OCH3), 51.9 (C-4B), 49.2 (C-4Ј), 44.0 (C-5Ј),
36.6 (C-2B), 27.7 (C-3Ј), 26.7 (C-2Ј), 24.9 (Ar-CH3), 19.2
(C-6B), 18.3 (C-6A), 14.7 (C-6Ј); m/z 773 (MHϩ).
(C᎐O), 170.1 (C᎐O), 153.0 (C-1), 149.5 (C-5), 142.7 (C-6), 138.0
᎐
᎐
(C arom), 135.7 (C arom), 133.5 (CH arom), 129.6 (CH
arom), 129.0 (CH arom), 127.5 (CH arom), 100.8 (C-1D), 93.5
(C-2), 77.2 (C-3D), 72.2, 69.0, 67.9 (C-5D, -4D, -2D), 61.2
(Ar-OCH3), 60.7 (Ar-OCH3), 58.6 (Ar-CH2OSi), 57.7 (OCH3),
Methyl 4,6-dideoxy-4-{4-S-[4-(6-deoxy-3-O-methyl-ꢁ-L-manno-
pyranosyloxy)-3-iodo-5,6-dimethoxy-2-methylbenzoyl]-2,6-
dideoxy-4-thio-ꢂ-D-ribo-hexopyranosyloxyamino}-2-O-[4Ј-(ethyl-
amino)butyl]-ꢁ-D-glucopyranoside 4
26.8 [(CH ) CSi], 25.5 (Ar-CH ), 21.0 (CH C᎐O), 19.3 [(CH ) -
᎐
3
3
3
3
3 3
CSi], 17.3 (C-6D); m/z 824 (M ϩ NH4)ϩ (Found: C, 55.18; H,
Preparation of mixed anhydride 31. Pyridine (6 µL, 70 µmol)
and phenyl dichlorophosphate (5 µL, 35 µmol) were added to a
stirred solution of compound 298h (see below) (12 mg, 23 µmol)
in DME (115 µL) at 0 ЊC. The mixture was stirred for 1 h at
room temperature.
5.94. C37H47IO10Si requires C, 55.09; H, 5.87%).
4-(Hydroxymethyl)-2-iodo-5,6-dimethoxy-3-methylphenyl 2,4-
di-O-acetyl-6-deoxy-3-O-methyl-ꢁ-L-mannopyranoside 37
To a stirred solution of compound 36 (38 mg, 47 µmol) in dry
THF (2.8 mL) at room temperature was added solid TBAF (49
mg, 188 µmol). The mixture was stirred for 4 h, then evaporated
to dryness. Column chromatography (heptane–ethyl acetate
1:1) provided the alcohol 37 (20 mg, 75%) as a colorless oil;
[α]D Ϫ19 (c 1.36, CHCl3); νmax (thin film)/cmϪ1 3441 (OH), 1748
Preparation of 4. Tri-n-butylphosphine (63 µL, 272 µmol)
was added to a stirred solution of disulfide 33 (5.3 mg, 6 µmol)
in DME (110 µL). The mixture was stirred for 1 h at room
temperature and then was added to a stirred solution of the
mixed anhydride 31 at 0 ЊC. The mixture was stirred for 24 h at
room temperature, filtered through a short pad of Celite and
the solvent was removed in vacuo. Column chromatography
(CH2Cl2–MeOH 8:1 containing 1% of 32% aq. ammonia) gave
a white solid (12 mg). This solid was dissolved in CH2Cl2 (0.5
mL), then the solution was saturated with ammonia and stirred
at room temperature for 15 min. The resulting solution was
filtered on Celite and the solvent was removed to afford com-
pound 4 (8 mg, 72%) as a white solid; [α]D Ϫ5 (c 0.54, CHCl3);
νmax (thin film)/cmϪ1 3417 (NH, OH), 1660 [(C᎐O)S]; δ (250
(C᎐O); δ (250 MHz; CDCl3) 1.19 (3H, d, J5,6 6.5, H3-6), 2.13
᎐
H
(3H, s, OAc), 2.16 (3H, s, OAc), 2.56 (3H, s, CH3), 3.44 (3H, s,
OCH3), 3.83 (3H, s, OCH3), 3.90 (3H, s, OCH3), 4.04 (1H, dd,
J2,3 3.5, J3,4 10.0, H-3), 4.37 (1H, dq, J4,5 10.0, J5,6 6.5, H-5), 4.76
(2H, s, CH2), 5.10 (1H, dd, J3,4 = J4,5 = 10.0, H-4), 5.60 (1H, d,
J1,2 2.0, H-1), 5.76 (1H, dd, J1,2 2.0, J2,3 3.5, H-2); δC (62.9 MHz;
CDCl ) 170.2 (C᎐O), 170.1 (C᎐O), 153.2 (C-1), 149.7 (C-5),
᎐
᎐
3
142.8 (C-6), 137.0 (C-3), 128.9 (C-4), 100.6 (C-1D), 93.8
(C-2), 76.4 (C-3D), 72.1, 69.0, 67.9 (C-5D, -4D, -2D), 61.5
(Ar-OCH3), 60.8 (Ar-OCH3), 58.2 (Ar-CH2OSi), 57.7 (OCH3),
᎐
H
MHz; CDCl3) 1.26 (3H, t, J5Ј,6Ј 7.5, H3-6Ј), 1.27 (3H, d, J5,6 6.0,
H3-6D), 1.31 (3H, d, J5,6 6.0, H3-6A), 1.36 (3H, d, J5,6 6.0,
H3-6B), 1.74 (1H, m, H-2axB), 1.87 (4H, m, H2-2Ј, -3Ј), 2.00
25.2 (Ar-CH ), 21.0 (CH C᎐O), 17.4 (C-6D); m/z 586 (M ϩ
᎐
3
3
NH4)ϩ (Found: C, 44.45; H, 5.17. C21H29IO10 requires C, 44.38;
H, 5.14%).
(1H, ddd, H-2eqB), 2.32 (3H, s, CH3), 2.41 (1H, dd, J3,4
=
J4,5 = 10.0, H-4A), 2.74 (1H, m, H-4Ј), 2.89 (2H, q, J5Ј,6Ј 7.5, H2-
5Ј), 2.89 (1H, m, H-4Ј), 3.37 (3H, s, OCH3), 3.40 (1H, dd, J2,1
3.5, J2,3 10.0, H-2A), 3.54 (3H, s, OCH3), 3.61 (1H, dd,
J3,4 = J4,5 = 9.5, H-4D), 3.68 (1H, dd, J4,3 2.5, J4,5 10.0, H-4B),
3.61–3.72 (2H, m, H2-1Ј), 3.80 (3H, s, OCH3), 3.81 (1H, dd, J2,3
3.0, J3,4 9.5, H-3D), 3.82 (1H, m, H-5A), 3.85 (3H, s, OCH3),
4-(2,4-Di-O-acetyl-6-deoxy-3-O-methyl-ꢁ-L-mannopyranosyl-
oxy)-3-iodo-5,6-dimethoxy-2-methylbenzoic acid 38
To a stirred solution of alcohol 37 (125 mg, 220 µmol) in CCl4–
CH3CN (1:1; 3 mL) at 0 ЊC were successively added water (4.5
mL), sodium periodate (188 mg, 879 µmol) and ruthenium tri-
chloride hydrate (12 mg, 55 µmol). The mixture was vigorously
stirred for 1 h at room temperature, diluted with water and
extracted with CH2Cl2. The aqueous phase was acidified with
acetic acid, extracted (5×) with CH2Cl2, and the extracts were
dried over MgSO4. Column chromatography (heptane–ethyl
acetate 1:1 containing 1% acetic acid) provided acid 38 (76 mg,
4.02 (1H, dq, J5,6 6.0, J5,4 10.0, H-5B), 4.05 (1H, dd, J3,4
=
J2,3 = 10.0, H-3A), 4.16 (1H, dq, J4,5 9.5, J5,6 6.0, H-5D), 4.26
(1H, m, H-3B), 4.45 (1H, dd, J1,2 2.0, J2,3 3.0, H-2D), 4.75 (1H,
d, J2,1 3.5, H-1A), 5.06 (1H, dd, J1,2eq 2.0, J1,2ax 10.0, H-1B), 5.69
(1H, d, J1,2 2.0, H-1D), 6.65 (1H, s, NHO); δC (62.9 MHz;
CDCl ) 192.2 (C᎐O), 151.3 (C-4), 150.6 (C-6), 142.9 (C-5), 133.4
᎐
3
(C-2), 130.4 (C-1), 102.5 (C-1D), 99.7 (C-1B), 97.2 (C-1A), 93.4
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
313

View Article Online
60%) as a colorless oil; νmax (thin film)/cmϪ1 3423 (OH), 1738
(C᎐O), 1643 (CO H); δ (250 MHz; CDCl3) 1.19 (3H, d, J5,6
6.5, H3-6), 2.13 (3H, s, OAc), 2.17 (3H, s, OAc), 2.49 (3H, s,
CH3), 3.44 (3H, s, OCH3), 3.85 (3H, s, OCH3), 3.92 (3H, s,
OCH3), 4.04 (1H, dd, J2,3 3.5, J3,4 10.0, H-3), 4.33 (1H, dq, J4,5
10.0, J5,6 6.5, H-5), 5.10 (dd, 1H, J3,4 = J4,5 = 10.0, H-4), 5.67
(1H, d, J1,2 2.0, H-1), 5.75 (1H, dd, J1,2 2.0, J2,3 3.5, H-2);
(250 MHz; CDCl3) 0.66 [12H, 2 q, J 7.5, 2 × Si(CH2CH3)3], 0.99
[18H, 2 t, J 7.5, 2 × Si(CH2CH3)3], 1.24 (3H, d, J5,6 6.5, H3-6D),
1.34 (3H, d, J5,6 6.5, H3-6B), 1.50–1.80 (6H, m, OTHP), 1.92
(1H, dt, J2ax,1 = J2ax,3 = 4.0, J2eq,2ax 14.0, H-2Bax), 2.14 (1H, m,
J2eq,1 4.0, J2eq,3 6.5, J2eq,2ax 14.0, H-2Beq), 2.44 (3H, s, CH3),
3.33–3.50 (2H, m, OTHP), 3.35 (3H, s, OCH3), 3.44 (3H, s,
OCH3), 3.60 (1H, dd, J2,3 2.0, J3,4 9.0, H-3D), 3.74 (1H, dd,
J3,4 = J4,5 = 9.0, H-4D), 3.80 (3H, s, OCH3), 3.89 (3H, s, OCH3),
4.10 (1H, dq, J4,5 9.0, J5,6 6.5, H-5D), 4.33 (2H, m, H-3B,
᎐
2
H
δ (62.9 MHz; CDCl ) 170.2 (C᎐O), 170.2 (C=O), 151.4, 151.1
᎐
C
3
(C-4, C-5), 142.7 (C-6), 134.6 (C-3), 125.9 (C-1), 100.6 (C-1D),
97.3 (C-2), 77.2 (C-3D), 72.1, 69.2, 67.8 (C-5D, -4D, -2D), 61.8
(Ar-OCH3), 60.9 (Ar-OCH3), 57.8 (OCH3), 26.1 (Ar-CH3), 21.0
-5B), 4.45 (1H, dd, J1,2 = J2,3 = 2.0, H-2D), 4.70 (1H, t, J1,2eq
=
J1,2ax = 4.0, H-1B), 4.83 (1H, m, OTHP), 5.05 (1H, dd, J4,3
3,0, J4,5 7.5, H-4B), 5.41 (1H, d, J1,2 2.0, H-1D); δC (62.9
(CH C᎐O), 17.4 (C-6D); m/z 600 (M ϩ NH )ϩ.
᎐
3
4
MHz; CDCl ) 166.7 (C᎐O), 151.8, 151.3 (C-6, -4), 143.0 (C-5),
᎐
3
134.2 (C-2), 125.8 (C-1), 104.5 (C-1D), 97.3 (C-1B), 95.0
(C-THP), 93.5 (C-3), 81.3 (C-3D), 77.2 (C-4B), 75.1, 72.3, 68.6,
66.8 (C-5D, -4D, -2D, -3B), 64.6 (C-5B), 62.2 (C THP),
61.5 (Ar-OCH3), 60.7 (Ar-OCH3), 57.2 (OCH3), 55.2 (OCH3),
31.1, 30.4 (C-2B, C THP), 26.1 (Ar-CH3), 25.5 (C THP), 19.3
(C THP), 18.0 (C-6D), 17.5 (C-6B), 6.9 (CH3CH2Si), 6.7
(CH3CH2Si), 5.1 (CH3CH2Si); 4.8 (CH3CH2Si).
4-(6-Deoxy-3-O-methyl-ꢁ-L-mannopyanosyloxy)-3-iodo-5,6-
dimethoxy-2-methylbenzoic acid 298h
Solid lithium hydroxide monohydrate (26 mg, 618 µmol) was
added to a stirred mixture of acid 38 (90 mg, 154 µmol) and
hydrogen peroxide (30% in water, 38 µL, 1.24 mmol) in a mix-
ture THF–water (3:1; 5 mL) at 0 ЊC. The resulting mixture was
stirred for 2 h at room temperature, acidified with 5% aq.
hydrochloric acid, concentrated in vacuo, and coevaporated
with toluene. Column chromatography (ethyl acetate–methanol
10:1 containing 1% acetic acid) provided diol 29 (61 mg, 79%)
as a white solid; νmax (thin film)/cmϪ1 3406 (OH), 1631 (CO2H);
δH (250 MHz; CDCl3) 1.30 (3H, d, J5,6 6.0, H3-6), 2.50 (3H, s,
CH3), 3.58 (3H, s, OCH3), 3.65 (1H, dd, J3,4 = J4,5 = 9.5, H-4),
3.86 (1H, dd, J2,3 3.5, J3,4 9.5, H-3), 3.86 (3H, s, OCH3), 3.94
(3H, s, OCH3), 4.19 (1H, dq, J4,5 9.5, J5,6 6.0, H-5), 4.48 (1H, dd,
J1,2 2.0, J2,3 3.5, H-2), 5.78 (1H, d, J1,2 2.0, H-1).
Methyl 2,6-dideoxy-4-O-[4-(6-deoxy-3-O-methyl-ꢁ-L-manno-
pyranosyloxy)-3-iodo-5,6-dimethoxy-2-methylbenzoyl]-ꢁ-D-ribo-
hexopyranoside 43
Cold 1% HCl solution in dry methanol (150 µL) was added to
ester 42 (14 mg, 15 µmol). The solution was stirred for 15 min at
room temperature, then neutralised with 5% aq. NaHCO3 and
evaporated to dryness. Column chromatography (dichloro-
methane–methanol 30:1) provided triol 43 (7 mg, 75%) as a
colorless oil; [α]D ϩ17 (c 0.70, CHCl3); δH (250 MHz; CDCl3)
1.30 (3H, d, J5,6 6.0, H3-6), 1.34 (3H, d, J5,6 6.0, H3-6), 2.04 (1H,
dt, J2ax,1 = J2ax,3 = 3.5, J2eq,2ax 15.0, H-2Bax), 2.19 (1H, ddd, J2eq,1
1.0, J2eq,2ax 15.0, H-2Beq), 2.42 (3H, s, CH3), 3.40 (3H, s,
OCH3), 3.56 (1H, d, J3,OH 8.5, OH-3B), 3.58 (3H, s, OCH3), 3.64
(1H, dd, J3,4 = J4,5 = 9.5, H-4D), 3.84 (3H, s, OCH3), 3.85 (1H,
m, H-3D), 3.91 (3H, s, OCH3), 4.13–4.32 (3H, m, H-5D, -3B,
-5B), 4.40 (1H, m, H-2D), 4.80 (1H, dd, J4,3 3.0, J4,5 10.0,
H-4B), 4.83 (1H, dd, J1,2ax 3.5, J1,2eq ≈ 1–2, H-1B), 5.74 (1H, d,
4-(6-Deoxy-3-O-methyl-2,4-bis-O-triethylsilyl-ꢁ-L-mannopyr-
anosyloxy)-3-iodo-5,6-dimethoxy-2-methylbenzoic acid 398f,32
To a stirred solution of acid 298h (43 mg, 86 µmol) in dichloro-
methane (1.3 mL) at 0 ЊC were successively added pyridine
(56 µL, 690 µmol), DMAP (42 mg, 345 µmol) and dropwise
triethylsilyl trifluoromethanesulfonate (97 µL, 431 µmol). The
solution was stirred for 1 h, at room temperature, then poured
into saturated aq. NaHCO3. The organic layer was separated,
dried over MgSO4, and the solvent removed in vacuo. Column
chromatography (heptane–ethyl acetate 2:1 containing 1%
acetic acid) provided acid 39 (50 mg, 80%) as a colorless oil;
δH (250 MHz; CDCl3) 0.60 [6H, q, J 8.0, Si(CH2CH3)3], [0.62
[6H, q, J 8.0, Si(CH2CH3)3], 0.94 [9H, t, J 8.0, Si(CH2CH3)3],
0.95 [9H, t, J 8.0, Si(CH2CH3)3], 1.21 (3H, d, J5,6 6.0, H3-6), 2.47
(3H, s, CH3), 3.40 (3H, s, OCH3), 3.56 (1H, dd, J2,3 2.5, J3,4 9.0,
H-3), 3.71 (1H, dd, J3,4 = J4,5 = 9.0, H-4), 3.79 (3H, s, OCH3),
3.90 (3H, s, OCH3), 4.08 (1H, dq, J4,5 9.0, J5,6 6.0, H-5), 4.41
(1H, dd, J1,2 = J2,3 = 2.5, H-2), 5.41 (1H, d, J1,2 2.0, H-1).
J1,2 1.5, H-1D); δC (62.9 MHz; CDCl ) 166.4 (C᎐O), 151.2,
᎐
3
151.1 (C-6, -4), 142.8 (C-5), 134.0 (C-2), 125.1 (C-1), 102.4
(C-1D), 98.4 (C-1B), 93.1 (C-3), 80.8 (C-3D), 77.2 (C-4B),
71.1 (C-4D), 70.3 (C-5D), 66.9 (C-2D), 65.3 (C-5B), 61.5
(Ar-OCH3), 61.0 (C-3B), 60.8 (Ar-OCH3), 57.1 (OCH3), 55.2
(OCH3), 35.2 (C-2B), 25.7 (Ar-CH3); 17.5 (C-6B, -6D).
Methyl 3-O-acetyl-2,6-dideoxy-4-O-[4-(2,4-di-O-acetyl-6-
deoxy-3-O-methyl-ꢁ-L-mannopyranosyl-oxy)-3-iodo-5,6-
dimethoxy-2-methylbenzoyl]-ꢁ-D-ribo-hexopyranoside 44
A solution of triol 43 (7 mg, 10.9 µmol) in a mixture of
acetic anhydride (0.2 mL) and pyridine (0.3 mL) was stirred for
3 h at room temperature and then for 2 h at 50 ЊC. The solution
was evaporated to dryness, then coevaporated with toluene.
Column chromatography (heptane–ethyl acetate 2:1) provided
triacetate 44 (7 mg, 83%) as a colorless oil; [α]D ϩ27 (c 0.70,
CHCl3); δH (250 MHz; CDCl3) 1.20 (3H, d, J5,6 6.0, H3-6), 1.32
(3H, d, J5,6 6.0, H3-6), 2.03 (1H, m, J2ax,1 4.5, J2ax,3 4.0, J2eq,2ax
15.0, H-2Bax), 2.05 (3H, s, OAc), 2.14 (3H, s, OAc), 2.17 (3H, s,
OAc), 2.26 (1H, m, J2eq,1 1.5, J2eq,3 4.0, J2eq,2ax 15.0, H-2Beq),
2.36 (3H, s, CH3), 3.36 (3H, s, OCH3), 3.44 (3H, s, OCH3), 3.84
(3H, s, OCH3), 3.85 (3H, s, OCH3), 4.04 (1H, dd, J4,3 10.0, J3,2
3.0, H-3D), 4.33 (2H, m, H-5D, -5B), 4.73 (1H, m, J1,2ax 4.5,
J1,2eq 1.5, H-1B), 4.94 (1H, dd, J4,3 3.0, J4,5 9.0, H-4B), 5.11 (1H,
dd, J3,4 = J4,5 = 10.0, H-4D), 5.34 (1H, m, J3,2ax = J3,2eq = 4.0, J4,3
3.0, H-3B), 5.64 (1H, d, J1,2 2.0, H-1D), 5.75 (1H, dd, J1,2 2.0,
Methyl 2,6-dideoxy-4-O-[4-(6-deoxy-3-O-methyl-2,4-bis-O-
triethylsilyl-ꢁ-L-mannopyranosyl-oxy)-3-iodo-5,6-dimethoxy-2-
methylbenzoyl]-3-O-(tetrahydropyran-2-yl)-ꢁ-D-ribo-hexo-
pyranoside 42
Methyl 2,6-dideoxy-3-O-(tetrahydropyran-2-yl)-α- and -β-D-
ribo-hexopyranoside 4124b (17 mg, 66 µmol) as a solution in
THF (0.1 mL) was stirred in the presence of sodium hydride
(60% dispersion in oil) (3 mg, 66 µmol) at 0 ЊC for 10 min and
for a further 1 h at room temperature.
Oxalyl dichloride (101 µL) was added at room temperature
to a stirred solution of acid 39 (16 mg, 22 µmol) in dichloro-
methane (0.5 mL). The resulting solution was stirred for 1 h
then the solvent was removed in vacuo. Acid chloride 408f was
taken up in THF (0.1 mL) and added to the above solution of
the sodium salt of carbohydrate 41 at 0 ЊC. The mixture was
stirred for 30 min at room temperature, then neutralised with
saturated aq. NaHCO3 and evaporated to dryness. Column
chromatography (heptane–ethyl acetate 8:1) provided ester 42
(14 mg, 67%) as a colorless oil; [α]D ϩ18 (c 1.00, CHCl3); δH
J3,2 3.0, H-2D); δC (62.9 MHz; CDCl ) 170.5 (C᎐O), 170.2
᎐
3
(C᎐O), 170.1 (C᎐O), 163.9 (C᎐O), 151.2; 150.9 (C-6, -4), 143.0
᎐
᎐
᎐
(C-5), 134.0 (C-2), 125.2 (C-1), 104.5 (C-1D), 97.3 (C-1B), 95.5
(C-3), 77.2 (C-3D, -4B), 73.6; 72.1; 69.1; 67.8 (C-5D, -4D, -2D,
-3B), 62.8 (C-5B), 61.4 (Ar-OCH3), 60.9 (Ar-OCH3), 57.8
314
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315

View Article Online
10082; (d) R. L. Halcomb, S. H. Boyer and S. J. Danishefsky,
(OCH3), 55.3 (OCH3), 33.1 (C-2B), 25.7 (Ar-CH3), 21.2
Angew. Chem., Int. Ed. Engl., 1992, 31, 338; (e) K. C. Nicolaou,
D. Clark, Angew. Chem., Int. Ed. Engl., 1992, 31, 855; ( f ) R. D.
Groneberg, T. Miyazaki, N. A. Stylianides, T. J. Schulze, W. Stahl,
E. P. Schreiner, T. Suzuki, Y. Iwabuchi, A. L. Smith and K. C.
Nicolaou, J. Am. Chem. Soc., 1993, 115, 7593; (g) K. C. Nicolaou,
C. W. Hummel, M. Nakada, K. Shibayama, E. N. Pitsinos,
H. Saimoto, Y. Mizuno, K. U. Baldenius and A. L. Smith, J. Am.
Chem. Soc., 1993, 115, 7625; (h) S. H. Kim, D. Augeri, D. Yang and
D. Kahne, J. Am. Chem. Soc., 1994, 116, 1766; (i) E. Da Silva,
J. Prandi and J. M. Beau, J. Chem. Soc., Chem. Commun., 1994,
2127; (j) R. L. Halcomb, S. H. Boyer, M. D. Wittman, S. H. Olson,
D. J. Denhart, K. K. C. Liu and S. J. Danishefsky, J. Am. Chem.
Soc., 1995, 117, 5720.
(CH C᎐O); 17.4 (C-6B, -6D).
᎐
3
3-O-Acetyl-2,6-dideoxy-4-O-[4-(6-deoxy-2,4-di-O-acetyl-3-O-
methyl-ꢁ-L-mannopyranosyloxy)3-iodo-5,6-dimethoxy-2-
methylbenzoyl]-ꢁ and -ꢂ-D-ribo-hexopyranose 7
A stirred solution of triacetate 44 (7 mg, 9 µmol) in water–
AcOH 2:1 (0.8 mL) was heated at reflux for 2 h. On cooling, the
solvent was removed under reduced pressure, and final traces
were removed by coevaporation (3×) with toluene. Column
chromatography (heptane–ethyl acetate 1:2) provided hemi-
acetal 7 (5 mg, 73%) as a colorless, oily, 3–4:1 mixture of β and
α anomers; major β-anomer: δH (250 MHz; CDCl3) 1.20 (3H, d,
J5,6 6.5, H3-6), 1.37 (3H, d, J5,6 6.0, H3-6), 1.86 (1H, ddd, J2ax,1
9.0, J2ax,3 2.5, J2eq,2ax 14.5, H-2Bax), 2.08 (3H, s, OAc), 2.14 (3H,
s, OAc), 2.17 (3H, s, OAc), 2.27 (1H, ddd, J2eq,1 2.0, J2eq,3 4.0,
J2eq,2ax 14.5, H-2Beq), 2.35 (3H, s, CH3), 2.88 (1H, d, J1,OH 6.5,
OH), 3.44 (3H, s, OCH3), 3.84 (3H, s, OCH3), 3.85 (3H, s,
OCH3), 4.04 (1H, dd, J4,3 10.0, J3,2 3.0, H-3D), 4.13 (1H, m,
H-5), 4.33 (1H, m, H-5), 4.90 (1H, dd, J4,3 3.0, J4,5 9.5, H-4B),
5.10 (1H, dd, J3,4 = J4,5 10.0, H-4D), 5.16 (1H, m, H-1B), 5.58
(1H, m, H-3B), 5.63 (1H, d, J1,2 2.0, H-1D), 5.74 (1H, dd, J1,2
2.0, J3,2 3.0, H-2D).
9 B. H. Long, J. Golik, S. Forenza, B. Ward, R. Rehfuss, J. C.
Dabrowiak, J. J. Catino, S. T. Musial and K. W. Brookshire and
T. W. Doyle, Proc. Natl. Acad. Sci. USA, 1989, 86, 2.
10 (a) T. Li, Z. Zeng, V. A. Estevez, K. U. Baldenius, K. C. Nicolaou
and G. F. Joyce, J. Am. Chem. Soc., 1994, 116, 3709; (b) M.
Chatterjee, S. C. Mah, T. D. Tullius and C. A. Townsend, J. Am.
Chem. Soc., 1995, 117, 8074; (c) C. Bailly and M. J. Waring, J. Am.
Chem. Soc., 1995, 117, 7311.
11 (a) S. Walker, D. Yang and D. Kahne, J. Am. Chem. Soc., 1991, 113,
4716; (b) S. Walker, J. Murnick and D. Kahne, J. Am. Chem. Soc.,
1993, 115, 7954; (c) S. Walker, A. H. Andreotti and D. Kahne,
Tetrahedron, 1994, 50, 1351.
12 For a preliminary account of part of this work, see S. Moutel and
J. Prandi, Tetrahedron Lett., 1998, 39, 9167.
13 T. Bamhaoud, J. M. Lancelin and J. M. Beau, J. Chem. Soc., Chem.
Commun., 1992, 1494.
14 S. Masamune, S. Kamata, J. Diakur, Y. Sugihara and G. S. Bates,
Can. J. Chem., 1975, 53, 3693.
15 (a) L. G. Paloma, J. A. Smith, W. J. Chazin and K. C. Nicolaou,
J. Am. Chem. Soc., 1994, 116, 3697; (b) N. Ikemoto, R. A. Kumar,
T. T. Ling, G. A. Ellestad, S. J. Danishefsky and D. J. Patel, Proc.
Natl. Acad. Sci. USA, 1995, 92, 10506; (c) R. A. Kumar, N. Ikemoto
and D. J. Patel, J. Mol. Biol., 1997, 265, 187.
Acknowledgements
We are grateful to Dr Michael Shipman (University of Exeter,
UK) for his help in the preparation of this paper. This work
was financially supported by the Ministère de l’Enseignement
Supérieur et de la Recherche.
16 For a preliminary account of part of this work, see S. Moutel and
J. Prandi, Tetrahedron Lett., 1998, 39, 9667.
17 (a) F. Y. Dupradeau, S. Allaire, J. Prandi and J. M. Beau,
Tetrahedron Lett., 1993, 34, 4513; (b) F. Y. Dupradeau, J. Prandi and
J. M. Beau, Tetrahedron, 1995, 51, 3205.
18 (a) R. K. Crossland and K. L. Servis, J. Org. Chem., 1970, 35, 3195;
(b) R. K. Crossland, W. E. Wells and V. J. Shiner Jr, J. Am. Chem.
Soc., 1971, 93, 4217.
19 R. R. Schmidt, Angew. Chem., Int. Ed. Engl., 1986, 25, 212.
20 Elevated temperatures solved the problem of multiple spectra due
to Fmoc rotamers in the 1H NMR analysis. Nicolaou recorded
1H NMR spectra in DMSO-d6 at 80 ЊC. (see refs. 8a and 8f ).
21 S. P. Douglas, D. M. Whitfield and J. J. Krepinsky, J. Carbohydr.
Chem., 1993, 12, 131.
22 G. Wulff and G. Röhle, Angew. Chem., Int. Ed. Engl., 1974, 13, 157.
23 (a) P. J. L. Daniels, A. K. Mallams and J. J. Wright, J. Chem. Soc.,
Chem. Commun., 1973, 675; (b) F. Arcamone, A. Bargiotti,
G. Cassinelli, S. Redaelli, S. Hanessian, A. Di Marco, A. M.
Casasza, T. Dasdia, A. Necco, P. Reggiani and R. Supino, J. Med.
Chem., 1976, 19, 733.
24 (a) T. Y. R Tsai, H. Jin and K. Wiesner, Can. J. Chem., 1984, 62,
1403; (b) K. Wiesner, T. Y. R. Tsai and H. Jin, Helv. Chim. Acta,
1985, 68, 300.
25 K. Tanemura, T. Suzuki and T. Horaguchi, J. Chem. Soc., Chem.
Commun., 1992, 979.
26 The selectivity of the glycosylation was determined at this stage of
the synthesis.
References and notes
1 (a) M. D. Lee, T. S. Dunne, M. M. Siegel, C. C. Chang, G. O.
Morton and D. B. Borders, J. Am. Chem. Soc., 1987, 109,
3464; (b) M. D. Lee, T. S. Dunne, C. C. Chang, G. A. Ellestad,
M. M. Siegel, G. O. Morton, W. J. McGahren and D. B. Borders,
J. Am. Chem. Soc., 1987, 109, 3466; (c) Enediyne Antibiotics as
Antitumor Agents, ed. D. B. Borders and T. W. Doyle, Marcel
Dekker, New York, 1995.
2 (a) J. Golik, J. Clardy, G. Dubay, G. Groenewold, H. Kawaguchi, M.
Konishi, B. Krishnan, H. Ohkuma, K. Saitoh and T. W. Doyle,
J. Am. Chem. Soc., 1987, 109, 3461; (b) J. Golik, G. Dubay, G.
Groenewold, H. Kawaguchi, M. Konishi, B. Krishnan, H. Ohkuma,
K. Saitoh and T. W. Doyle, J. Am. Chem. Soc., 1987, 109, 3462.
3 (a) N. Zein, W. J. McGahren, G. O. Morton, J. Ashcroft and
G. A. Ellestad, J. Am. Chem. Soc., 1989, 111, 6888; (b) S. Walker,
R. Landovitz, W. D. Ding, G. A. Ellestad and D. Kahne, Proc. Natl.
Acad. Sci. USA, 1992, 89, 4608; (c) J. J. Hangeland, J. J. De Voss,
J. A. Heath, C. A. Townsend, W. D. Ding, J. S. Ashcroft and
G. A. Ellestad, J. Am. Chem. Soc., 1992, 114, 9200; (d) P. C. Dedon,
A. A. Salzberg and J. Xu, Biochemistry, 1993, 32, 3617.
4 (a) H. Kishikawa, Y. P. Jiang, J. Goodisman and J. C. Dabrowiak,
J. Am. Chem. Soc., 1991, 113, 5434; (b) D. F. Christner, B. L. Frank,
J. W. Kozarich, J. A. Stubbe, J. Golik, T. W. Doyle, I. A. Rosenberg
and B. Krishnan, J. Am. Chem. Soc., 1992, 114, 8763; (c) L. Yu,
J. Golik, R. Harrison and P. Dedon, J. Am. Chem. Soc., 1994, 116,
9733.
5 (a) T. Lockhart and R. G. Bergman, J. Am. Chem. Soc., 1981, 103,
4091; (b) J. J. De Voss, J. J. Hangeland and C. A. Townsend, J. Am.
Chem. Soc., 1990, 112, 4554.
27 (a) K. C. Nicolaou, T. Ebata, N. A. Stylianides, R. D. Groneberg
and P. J. Carrol, Angew. Chem., Int. Ed. Engl., 1988, 27, 1097;
(b) K. Van Laak and H. D. Scharf, Tetrahedron, 1989, 45, 5511.
28 H. Liu and S. I. Sabesan, Can. J. Chem., 1980, 58, 2645.
29 G. H. Veeneman, S. H. Van Leeuwen and J. H. Van Boom,
Tetrahedron Lett., 1990, 31, 1331.
30 H. J. Carlsen, T. Katsuki, V. S. Martin and K. B. Sharpless, J. Org.
Chem., 1981, 46, 3996.
31 D. A. Evans, T. C. Britton and J. A. Ellman, Tetrahedron Lett., 1987,
28, 6141.
32 K. C. Nicolaou, R. D. Groneberg, N. A. Stylianides and T.
Miyazaki, J. Chem. Soc., Chem. Commun., 1990, 1275.
33 (a) N. Kunesch, C. Miet and J. Poisson, Tetrahedron Lett., 1987, 28,
3569; (b) U. Ellervik and G. Magnusson, Tetrahedron Lett., 1997, 38,
1627.
34 G. Krishnamurthy, W. D. Ding, L. OЈBrien and G. A. Ellestad,
Tetrahedron, 1994, 50, 1341.
6 (a) N. Zein, A. M. Sinha, W. J. McGahren and G. A. Ellestad,
Science, 1988, 240, 1198; (b) R. C. Hawley, L. L. Kiesling and
S. L. Schreiber, Proc. Natl. Acad. Sci. USA, 1989, 86, 1105.
7 (a) N. Zein, M. Poncin, R. Nilakantan and G. A. Ellestad, Science,
1989, 244, 697; (b) J. J. De Voss, C. A. Townsend, W. D. Ding,
G. O. Morton, G. A. Ellestad, N. Zein, A. B. Tabor and S. L.
Schreiber, J. Am. Chem. Soc., 1990, 112, 9669; (c) S. C. Mah,
C. A. Townsend and T. D. Tullius, Biochemistry, 1994, 33, 614.
8 (a) K. C. Nicolaou, R. D. Groneberg, T. Miyazaki, N. A.
Stylianides, T. J. Schulze and W. Stahl, J. Am. Chem. Soc., 1990, 112,
8193; (b) R. L. Halcomb, M. D. Wittman, S. H. Olson and
S. J. Danishefsky, J. Am. Chem. Soc., 1991, 113, 5080; (c) K. C.
Nicolaou, C. W. Hummel, E. N. Pitsinos, M. Nakada, A. L. Smith,
K. Shibayama and H. Saimoto, J. Am. Chem. Soc., 1992, 114,
J. Chem. Soc., Perkin Trans. 1, 2001, 305–315
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