Total synthesis of nucleobase-modified adenophostin A mimics

Article abstract of DOI:10.1002/1521-3765(20011119)7:22<4937::AID-CHEM4937>3.0.CO;2-G

The adenophostins exhibit approximately 10-100 times higher receptor binding and Ca²⁺ mobilising potencies in comparison with the natural second messenger D-myo-inositol 1,4,5-trisphosphate [InS(1,4,5)P₃]. Despite many synthetic atte

Full text of DOI:10.1002/1521-3765(20011119)7:22<4937::AID-CHEM4937>3.0.CO;2-G

FULL PAPER
Total Synthesis of Nucleobase-Modified Adenophostin A Mimics
Satoshi Shuto,[a, b] Graeme Horne,[a] Rachel D. Marwood,[a] and Barry V. L. Potter*[a]
Abstract: The adenophostins exhibit
approximately 10 ± 100 times higher re-
ceptor binding and Ca2‡ mobilising po-
tencies in comparison with the natural
second messenger d-myo-inositol 1,4,5-
trisphosphate [Ins(1,4,5)P3]. Despite
many synthetic attempts to determine
the minimal structural requirement for
this unusual behaviour of the adeno-
phostins, few related simplified ana-
logues displaying higher activity than
that of Ins(1,4,5)P3 have been reported.
However, biological evaluation of such
analogues has revealed that one of the
key factors for the enhanced biological
activity is the adenine moiety. To further
understand the effect that the adenine
base has upon the activity of the adeno-
phostins, congeners in which this func-
tionality is replaced by uracil, benzimi-
dazole, 2-methoxynaphthalene, 4-meth-
ylanisole and 4-methylnaphthalene
using the common intermediate 1,2-di-
O-acetyl-5-O-benzyl-3-O-(3,4-di-O-ace-
tyl-2,6-di-O-benzyl-a-d-glucopyrano-
syl)-ribofuranose have been synthesised
using a base replacement strategy. The
synthesis of the uracil and benzimida-
zole analogues was achieved using the
Vorbrüggen condensation procedure.
The 1'-C-glycosidic analogues were pre-
pared using Friedel ± Crafts type C-aryl
glycosidation
reactions.
Phosphate
groups were introduced using the phos-
phoramidite method with subsequent
removal of all-benzyl protecting groups
by catalytic hydrogenation or catalytic
hydrogen transfer. Apart from one ana-
logue with an a-glycosidic linkage all
compounds were more potent than
Ins(1,4,5)P3 and most tended more to-
wards adenophostin in activity. These
analogues will be valuable tools to un-
ravel the role that the adenine moiety
plays in the potent activity of the
adenophostins and demonstrate that this
strategy is effective at producing highly
potent ligands.
Keywords: adenophostin ´ C-glyco-
sides ´ cyclitols ´ signal transduction
Recently, adenophostins A (2) and B (3) were isolated from
Pencillium brevicompactum[6] and have been shown to be full
agonists with affinities for Ins(1,4,5)P3 receptors that are 10 ±
100 fold greater than Ins(1,4,5)P3.[6±10] Chemically, the ad-
enophostins resemble Ins(1,4,5)P3 in that the trans diequato-
rial bisphosphate arrangement flanked by a hydroxyl group
(C-2'') which has been identified as a key point of the
biological activity of Ins(1,4,5)P3 is present (Figure 2).
Consequently all synthetic adenophostin analogues, to date,
have this arrangement conserved. Attempts to determine
which of the remaining structural features of the adenophos-
tins are responsible for their high affinity interactions with
Ins(1,4,5)P3 receptors have resulted in the synthesis and
biological evaluation of several related compounds[9±11] in-
cluding 4 ± 9 (Figure 1). To date, only one compound,
possessing a ring-opened ribose surrogate ªacyclophostinº[11h]
has shown similar activity.[11f] From these studies (summarised
in the SAR of Figure 2) the following observations regarding
the structural requirements for adenophostin-like activity
were apparent: 1) the a-d-glucopyranose structure is a good
bioisostere of the myo-inositol backbone of Ins(1,4,5)P3;
2) the three-dimensional arrangement of the three phosphate
groups of adenophostin and its analogues is essential for
biological activity; and 3) the adenine moiety enhances
activity. To further understand the role that the adenine
Introduction
The intracellular messenger 1-d-myo-inositol 1,4,5-trisphos-
phate [Ins(1,4,5)P3, 1] (Figure 1) mobilises Ca2‡ from intra-
cellular stores upon binding to its specific receptor;[1] this
results in an increase in cytosolic Ca2‡ concentration that can
regulate intracellular functions and control further release of
Ca2‡ from intracellular stores.[2] Because of its significant
biological importance[3, 4] numerous analogues of Ins(1,4,5)P3
have been extensively studied to develop specific ligands for
the Ins(1,4,5)P3 receptor to elucidate mechanistic aspects of
Ins(1,4,5)P3-mediated Ca2‡ signalling pathways.[5] However,
to date none of these inositol-based analogues has surpassed
Ins(1,4,5)P3 in binding affinity for the Ins(1,4,5)P3 receptor or
in Ca2‡ mobilising ability.
[a] Prof. B. V. L. Potter, Prof. S. Shuto, G. Horne, R. D. Marwood
Wolfson Laboratory of Medicinal Chemistry
Department of Pharmacy and Pharmacology
University of Bath
Claverton Down, Bath, BA2 7AY (UK)
Fax : (‡44)1225-826114
E-mail: b.v.l.potter@bath.ac.uk
[b] Prof. S. Shuto
Present address: Graduate School of Pharmaceutical Sciences
Hokkaido University
Kita-12, Nishis-6, Kita-Ku, Sapporo 060-0812 (Japan)
Chem. Eur. J. 2001, 7, No. 22
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4937

B. V. L. Potter et al.
FULL PAPER
has three additional ªpotentialº
hydrogen-bonding sites (N1, N3
and N7 in the adenine ring)
which could help explain the
high potency of interaction be-
tween adenophostin and the
Ins(1,4,5)P3 receptor that is ob-
served. To investigate the po-
tential of such hydrogen bond-
ing between both the N1, N3
and N7 in adenophostin with
binding site residues in the
Ins(1,4,5)P3 receptor, and the
extent to which such interac-
tions and/or hydrophobic inter-
actions might contribute to the
binding efficiency and potency,
adenophostin analogues in
which the adenine ring has been
replaced with nucleobase sur-
rogates are required. We now
report here further elaboration
of our general methodology[12a]
with the synthesis of adeno-
phostin analogues in which the
adenine ring has been replaced
by uracil (12), benzimidazole
NH2
N
N
N
HO
N
RO
2-O3PO
2-O3PO
O
OH
HO
O
2-O3PO
2-O3PO
2-
OPO3
HO
2-
O
OPO3
HO
1
2: R = H
3: R = Ac
R2 R3
O
R
2-O3PO
2-O3PO
R1
O
HO
2-O3PO
2-O3PO
2-O3PO
2-O3PO
O
O
HO
O
HO
2-
HO
O
OPO3
2-
OPO3
2-
OPO3
7: R1 = R2 = CH2OH, R3 = OCH3
8: R1 = CH2OH, R2 = R3 = H
9: R1 = R2 = R3 = H
4: R = CH2OH
5: R = H
6
N
N
N
N
HO
N
HO
N
HO
2-O3PO
HO
O
O
2-O3PO
2-O3PO
O
O
2-O3PO
HO
2-
HO
2-
O
OPO3
O
11
OPO3
10
O
N
N
N
NH
O
HO
HO
HO
2-O3PO
HO
2-O3PO
2-O3PO
O
O
O
O
2-O3PO
HO
2-
HO
2-
O
OPO3
O
OPO3
13
12
Me
(13),
2-methoxynaphthalene
Me
(14), 4-methylanisole (15) and
4-methylnaphthalene (16) (Fig-
ure 1). Some of these com-
pounds have been reported in
preliminary form.[12b]
HO
MeO
HO
O
OMe
HO
HO
2-O3PO
O
HO
O
HO
2-O3PO
2-O3PO
2-O3PO
2-O3PO
O
O
2-O3PO
O
HO
2-
2-
HO
O
OPO3
O
OPO3
HO
2-
O
OPO3
16
14
15
Figure 1. Ins(1,4,5)P3 (1), the adenophostins (2, 3) and analogues (4 ± 16).
Results and Discussion
Effects of stereochemistry of
glycosidic linkage and
changes to the H-bonding
character and hydrophobicity
of the aromatic ring system
with regard to activity
unknown.
The synthesis of adenophostin
analogues 12 ± 16 utilised the
common disaccharide 1,2-di-O-
NH2
5''-Position has minimal effect on activity
N
N
(similar to 3-hydroxyl of Ins(1,4,5)P3)
HO
N
N
HO
2- O3PO
2- O3PO
O
acetyl-5-O-benzyl-3-O-(3,4-di-
3'',4''-Bisphosphate mimics the
4,5-bisphosphate of Ins(1,4,5)P3
O
O-acetyl-2,6-di-O-benzyl-a-d-
HO
2-
glucopyranosyl)-ribofuranose
(20, Figure 3) which has previ-
ously been prepared in this
O
OPO3
2'-Phosphate group not essential
for activity but has an
"enhancing" effect (similar to
1-phosphate of Ins(1,4,5)P3)
2''-Hydroxyl mimics the
6-hydroxyl of Ins(1,4,5)P3
laboratory and utilised in the
Figure 2. Key features of adenophostin A that contribute to its high-affinity binding at the Ins(1,4,5)P3 receptor.
synthesis of adenophostin ana-
logues.[12]
moiety plays in the high potency of the adenophostins (e.g.
hydrogen bonding, hydrophobic interaction or a combination
of the two) and what components of the adenine ring, if any,
are instrumental for such activity, we recently reported the
synthesis and evaluation of two adenophostin analogues in
which the adenine moiety was replaced with an imidazole ring
(10) and a purine ring (11).[12] The results of this study
suggested that, although a purine ring (or equivalent) is
necessary for high potency, the 6-amino substituent does not
contribute greatly to the activity of adenophostin A and thus a
hydrogen-bond interaction with the receptor via the N6-
amino group appears to be unlikely. However, adenophostin
This intermediate provides an excellent starting place for
the synthesis of adenophostin analogues and similar com-
pounds; the incorporation of acetates at positions 1 and 2 are
a prerequisite for Vorbrüggen condensation and Friedel ±
Crafts type C-aryl glycosidation, with the additional incorpo-
ration of acetates at positions 3' and 4' allowing for one-step
deprotection to yield the triols required for phosphorylation.
Additionally, the orthogonal benzyl groups at positions 5, 2'
and 6' would remain in place until the final deprotection step.
In this paper we explore further the versatility of 20 and have
also made some improvements en route to 20. Although the
disaccharide 20 is a versatile intermediate for synthesising
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Adenophostin A Mimics
4937±4946
method yielded 20 in 80%
overall yield and was a more
convenient procedure than the
previously reported lower
yielding preparation.
The preparation of the uracil-
and benzimidazole-containing
targets (12 and 13) followed
the standard Vorbrüggen con-
densation procedure.[12] Treat-
ment of 20 with silylated uracil
(Scheme 2) and trimethylsilyl
Benzyl protecting groups at positions 5 and 6' provide
a stable "orthogonal" set of protecting groups
which allow for a one-step deprotection of
final compound.
BnO
Acetate at position 1 is
BnO
AcO
AcO
O
OAc
prerequisite for Vorbrüggen
and Friedel-Crafts reactions
O
Acetates at positions 3' and 4'
provide an "orthogonal" set
which can be deprotected
under mild conditions
BnO
O
OAc
Acetate at position 2 is necessary
for Vorbrüggen reaction and
provides part
of an "orthogonal" set of protecting
groups for deprotection and
subsequent phosphorylation
Benzyl protecting group at 2'-position
part of "orthogonal" set and aids the
formation of a-linked glycoside
Figure 3. Versatility and synthetic utility of orthogonally protected disaccharidic donor 20.
various adenophostin analogues, there were some drawbacks
in the previously reported route to 20. Consequently, techni-
cal improvements have been made, the results of which are
shown in Scheme 1. These improvements primarily concern
trifluoromethane sulfonate (TMSOTf) in acetonitrile at room
temperature afforded uracil derivative (21) in 93% yield.
BnO
OBn
O
OAc
O
AcO
AcO
BnO
O
OAc
OBn
O
OBn
O
20
i
HO
HO
AcO
AcO
D-glucose
i
ii
BnO OH
BnO
OAll
17
18
O
N
N
BnO
OBn
BnO
OBn
BnO
OBn
NH
O
BnO
OBn
O
N
O
O
ii
OAc
OAc
O
O
AcO
AcO
O
O
AcO
AcO
AcO
AcO
O
AcO
AcO
O
O
BnO
BnO
BnO
O
OAc
O
O
BnO
O
OAc
19
20
21
24
Scheme 1. Details regarding further synthetic information can be found in
the original paper[12a] i) a) Ac2O, DMAP, CH3CN, RT, 1 h; b) PdCl2,
MeOH, CH2Cl2, 10 ± 208C, 18 h (18, 93%); ii) a) 90% aq TFA, RT, 5 min;
b) Ac2O, DMAP, CH3CN, RT, 30 min (20, 80%).
iii
O
N
BnO
OBn
NH
O
BnO
OBn
N
N
O
O
O
HO
HO
O
HO
HO
two steps from the original synthesis; the synthesis of 3,4-di-
O-acetyl-2,6-di-O-benzyl-d-glucopyranoside (18), and the
synthesis of 1,2-di-O-acetyl-5-O-benzyl-3-O-(3,4-di-O-acetyl-
BnO
O
OH
BnO
O
OH
22
25
iv
2,6-di-O-benzyl-a-d-glucopyranosyl)-d-ribofuranose
(20).
For the original experimental details please refer to the
previously reported synthesis.[12a] Glycosyl donor 18 was
previously prepared by successive treatment of 17 with
Ac2O/pyridine and PdCl2 in MeOH/dichloromethane in
78% yield. However, it was found that this procedure was
occasionally low yielding. By altering the original conditions
for acetylation to three equivalents of Ac2O and three
equivalents of DMAP in acetonitrile, with subsequent re-
moval of the anomeric O-allyl group we were able to obtain 18
reproducibly in high yield (>90%). Further problems with
the original synthesis of 20 occurred with the acidic hydrolysis
of the cis-isopropylidene group of 19. Previously, this step was
carried out by refluxing an AcOH/H2O solution of 19 in the
presence of ethylene glycol. It was found that this reaction was
difficult to reproduce in the reported yield and frequently
yielded side-products. Furthermore, the purification was
problematic due to the difficulty in separating the resulting
diol from ethylene glycol. Consequently, a more convenient
method for the synthesis of 20 was required. Treatment of 19
with 90% aqueous TFA for five minutes at room temperature
followed by evaporation of reaction solvent, yielded the
corresponding cis-diol, which was acetylated without further
purification using Ac2O/DMAP in acetonitrile. This one-pot
O
N
BnO
OBn
NH
O
BnO
OBn
N
O
N
O
(BnO)2OPO
(BnO)2OPO
O
(BnO)2OPO
(BnO)2OPO
O
BnO
O
OPO(OBn)2
BnO
O
OPO(OBn)2
23
26
v
vi
O
N
HO
OH
NH
HO
OH
N
N
O
2- O3PO
2- O3PO
O
O
2- O3PO
2- O3PO
O
O
HO
2-
O
OPO3
HO
2-
O
OPO3
13
12
Scheme 2. i) Uracil, (NH4)2SO4, N,N,N',N'-hexamethyldisilazane, reflux,
3 h then residue dissolved in CH3CN, TMSOTf, room temperature, 1 h (21,
93%); ii) benzimidazole, (NH4)2SO4, N,N,N',N'-hexamethyldisilazane, re-
flux, 3 h then residue dissolved in acetonitrile, SnCl4, room temperature,
1 h (24, 51%); iii) NaOMe/MeOH, room temperature, 3 h (22, 88%; 25,
87%); iv) 1H-tetrazole, dibenzyl(diisopropyl)phosphoramidite, CH2Cl2,
788C, (23, 85%; 26, 79%); v) Pd/C, H2,
methanol, room temperature, 18 h (12, 98%); vi) Pd(OH)2, cyclohexene,
methanol, reflux, 90 min (13, 74%).
RT, 3 h, then, mCPBA,
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Similarly, reaction between silylated benzimidazole and
TMSOTf in acetonitrile afforded the desired benzimidazole
derivative 24 in only 44% yield. However, use of tin(iv)-
chloride (SnCl4) as promoter instead of TMSOTf improved
the yield of the benzimidazole derivative by 7%. The acetyl
Recently, Kuribayashi and co-workers have found that
SnCl4/AgCO2CF3 is an efficient combination to promote b-
selective Friedel ± Crafts type C-aryl glycosidation reac-
tions.[16f,g] A variety of C-aryl glycosides were prepared using
this system from 1-O-acetyl sugars and aromatics substituted
with a methoxy group. The yields for these conversions were
42 ± 89% (a:b, 26:74 to 0:100); the tri-O-acetyl-b-anisoyl-
ribofuranose was obtained as the major product in 62% yield
(a:b, 26:74) with per-acetylated ribofuranose as the glycosyl
donor. Application of this methodology to common inter-
mediate 20 and 2-methoxynaphthalene using conditions
similar to those of Kuribayashi (donor:acceptor:SnCl4:
AgCO2CF3 ˆ 1:2:1.5:3, CH2Cl2, 08C) gave the desired C-gly-
coside in only 35% yield as an anomeric mixture (27, a:b ˆ
1:8). Adaptation of the Kuribayashi conditions (donor:
Â
groups of 21 and 24 were removed under Zemplen condi-
tions[13] yielding triols 22 and 25, respectively. Phosphate
groups were introduced using the phosphoramidite method.
Treatment of 22 and 25 with dibenzyldiisopropylphosphor-
amidite and 1H-tetrazole in dichloromethane followed by
oxidation with mCPBA provided the corresponding tris(di-
benzylphosphate) derivatives 23 and 26, respectively. Oxida-
tion of the intermediate trisphosphites was carried out at
room temperature or at 208C. Simultaneous removal of all
benzyl protecting groups was investigated by catalytic hydro-
genation. When uridine derivative 23 in methanol was treated
with Pd/C under atmospheric pressure of H2 target compound
12 was obtained in high yield. However, similar treatment of
the benzimidazole derivative 26 resulted in reduction of the
aromatic aglycon moiety (analysis of reaction product by
1H NMR). Removal of the benzyl protecting groups of 26 was
achieved by catalytic hydrogen transfer[14] using palladium
hydroxide [Pd(OH)2] as catalyst and cyclohexene as transfer
reagent providing 13 in 74% yield.
acceptor:SnCl4:AgCO2CF3 ˆ 1:20:1.5:2,
CHCl3,
208C,
Scheme 3) resulted in a vast improvement in the overall yield
R1
R2
BnO
OBn
O
BnO
OBn
O
O
i
OAc
OAc
O
AcO
AcO
AcO
AcO
BnO
BnO
O
O
OAc
27: R1= OMe, R2= H
33: R1= H, R2= Me
20
Attention was now turned to the construction of the 1' C-
aryl glycosides (14 ± 16). O-Glycosides are usually prepared
by reaction of an appropriate glycosyl donor, which is usually
electrophilic and activated at the anomeric position, with a
nucleophilic glycosyl acceptor in the presence of a promoter.
The extension of this methodology to the synthesis of C-aryl
glycosides can be considered to be an example of the Friedel ±
Crafts reaction.[15, 16] However, due to the weak nucleophilic-
ity of the aryl ring, strong Lewis acids are often required as
promoters.[17] This can be overcome by using an aromatic
moiety which has been activated by electron-donating sub-
stituents, such as a hydroxyl or methoxy group or a fused
second aromatic group, which require milder conditions for
activation. Generally, carbohydrates bearing either acetyl or
halogeno groups at the anomeric position are the donors used
with the acetates requiring stronger activation than the
halides. However, despite reduced reactivity, the anomeric
acetates are generally the higher yielding. Another important
factor in the success of reaction is the ring size of the glycosyl
donor with pyranoses being more stereoselective than the
furanoses with anomeric mixtures often resulting from use of
the latter. When a pyranose sugar is used as the donor, unlike
O-glycosylation, the presence of a participating group[18] at
C-2 is not essential for controlling the stereoselectivity of the
reaction; generally the more stable b-anomer, in which an
aromatic ring at the anomeric position is in an equatorial
orientation, will prevail. It has been proposed that under
Lewis acidic conditions, these Friedel ± Crafts C-aryl
glycosidation products are in an equilibrium between the a-
and b-anomers involving the pyranose ring-opened inter-
mediate, giving rise to the thermodynamically favoured
product.[15a] However, due to the similarity in stability of
both anomers, when furanose sugars are used as the glycosyl
donor, the reactions often result in yielding the anomeric
mixture.
ii
R2
R1
BnO
R1
O
BnO
OBn
OBn
O
HO
R2
O
+
O
HO
HO
HO
BnO
O
OH
BnO
O
OH
28a: R1= OMe, R2= H
34a: R1= H, R2= Me
28: R1= OMe, R2= H
34: R1= H, R2= Me
iii
R2
R2
R1
O
R1
O
HO
BnO
OBn
OH
iv
2- O3PO
O
(BnO)2OPO
(BnO)2OPO
O
2- O3PO
HO
2-
BnO
O
OPO3
O
OPO(OBn)2
29: R1= OMe, R2= H
35: R1= H, R2= Me
14: R1= OMe, R2= H
16: R1= H, R2= Me
Scheme 3. i) 2-Methoxynaphthalene/1-methylnaphthalene, AgCO2CF3,
SnCl4, chloroform, room temperature, 45 min (27, 73%, a/b ratio 15:85
based on 1H NMR analysis; 33, 46%, %, a/b ratio 35:65 based on 1H NMR
analysis); ii) NaOMe/MeOH, room temperature, 3 h (28, 81%; 28a, 5%;
34, 57%; 34a, 31%); iii) 1H-tetrazole, dibenzyl(diisopropyl)phosphorami-
dite, CH2Cl2, RT, 3 h, then, mCPBA,
788C, (29, 92%; 35, 62%);
iv) Pd(OH)2, cyclohexene, methanol, reflux, 90 min (14, 64%; 16, 67%).
(74%) but no improvement in the anomeric selectivity.
Similar treatment of 4-methyl anisole and 1-methylnaphtha-
lene with 20 in the presence of SnCl4/AgCO2CF3 provided the
corresponding C-aryl glycosides 30 (see Scheme 4) in 67%
(a:b ˆ 1:1), and 33 (see Scheme 3) in 46% yield (a:b ˆ 1:2),
respectively. Although these anomeric mixtures were insep-
arable at this stage and their regiochemistries were not
confirmed, comparison with previous studies carried out on
Friedel± Crafts type C-glycosidation reactions with 2-methoxy-
naphthalene,[16f] 4-methylanisole,[16f] and 1-methylnaphthale-
ne[16c] suggested that C-glycosides had been formed at the
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Chem. Eur. J. 2001, 7, No. 22

Adenophostin A Mimics
4937±4946
1-position of 2-methoxynaphthalene, at the 2-position of
4-methylanisole, and at the 4-position of 1-methylnaphtha-
lene. The acetyl groups of the anomeric mixtures 27, 30, and 33
were removed with catalytic sodium methoxide in methanol
at room temperature yielding the corresponding triols, which
were separated by silica gel chromatography providing 28 and
28a, 31 and 31a, and 34 and 34a, respectively. The stereo- and
regiochemistries of C-glycosides 28 and 31 were confirmed by
MeO
BnO
OBn
BnO
OBn
O
O
i
OAc
OAc
O
O
AcO
AcO
AcO
AcO
Me
BnO
BnO
O
O
OAc
20
30
ii
Me
BnO
OBn
MeO
BnO
OBn
O
1
NOESY spectroscopy (Figure 4). The H NMR spectrum of
OMe
O
HO
HO
O
O
HO
HO
BnO
O
OH
BnO
Me
O
OH
BnO
BnO
O
O
31a
HO
HO
31
HO
HO
iii
OBn
OMe
OBn
H
H
H
BnO
BnO
O
O
O
O
Me
BnO
H
H
Me
H
BnO
HO
HO
MeO
OBn
H
H
O
H
OBn
OMe
(BnO)2OPO
(BnO)2OPO
O
MeO
O
(BnO)2OPO
(BnO)2OPO
O
H
BnO
(BnO)2OPO
H
O
BnO
Me
O
OPO(OBn)2
Figure 4. NOE correlations found for 28 and 31.
32
32a
iv
28 revealed two doublets at d ˆ 8.34 (H-8, J7,8 ˆ 8.3 Hz) and
7.74 (H-5, J5,6 ˆ 8.3 Hz) and a pair of doublets at 7.79 (H-4,
J3,4 ˆ 8.8 Hz) and 7.25 (H-3, J3,4 ˆ 8.8 Hz), which also support-
ed the conclusion that the glycosyl moiety had substituted at
the 1-position of the naphthalene ring. J1',2' values for several
C-aryl ribosides have been reported (J1',2' a-linked <J1',2' b-
linked, typically 2 ± 3 Hz for a-linked and 7 ± 8 Hz for b-
linked) and agreed well with those obtained for 28 and 28a
(3.4 Hz and 7.3 Hz, respectively), 31 and 31a (3.7 Hz and
4.9 Hz, respectively), and 34 and 34a (3.1 Hz and 3.5 Hz,
respectively). Phosphate units were introduced by the phos-
phoramidite method as previously described for 22 and 25.
Removal of all benzyl protecting groups was attempted by
catalytic hydrogenation but, as in the case for 26, the aromatic
moieties of 29, 32 and 35, appeared to be reduced (1H NMR
analysis). However, treatment with Pd(OH)2 in the presence
of cyclohexene in methanol at reflux yielded the correspond-
ing trisphosphates 14, 15 and 16, respectively.
Additionally, an a-C-aryl glycoside analogue of adeno-
phostin A was synthesised; the Friedel ± Crafts type acylation
of 20 with 4-methylanisole provided both anomers of 30 in
approximately equal amounts which after separation of the
triols 31 and 31a provided sufficient material for the synthesis
of the a-congener to be viable. Consequently, phosphitylation
followed by oxidation of triol 31a yielded fully protected 32a
which after deprotection yielded trisphosphate 15a as the free
acid (Scheme 4).
Me
HO
HO
MeO
OH
O
2- O3PO
2- O3PO
OH
OMe
O
O
2- O3PO
2- O3PO
O
OH
O
2-
OPO3
OH
2-
Me
O
OPO3
15a
15
Scheme 4. i) 4-Methylanisole, AgCO2CF3, SnCl4, chloroform, RT, 45 min
(30, 67%, a/b ratio 1:1 based on 1H NMR analysis); ii) NaOMe/MeOH,
RT, 3 h (31, 38%; 31a, 36%); iii) 1H-tetrazole, dibenzyl(diisopropyl)phos-
phoramidite, CH2Cl2, RT, 3 h, then, mCPBA, 788C, (32, 96%; 32a,
87%); iv) Pd/C, H2, methanol, RT, 75 min (15, 80%, 15a, 80%).
[99 nm]. Thus, all these compounds are more potent than
Ins(1,4,5)P3 and some have activity close to adenophostin A.
The a-configured 4-methylanisolyl derivative 15a showed a
drastic decrease in potency [1372 nm] relative to the a-anomer
[48 nm] and was even some 10 times weaker than Ins(1,4,5)P3.
These results show that a base-modification approach
represents a powerful strategy to develop high potency
ligands. They also show that simple ring replacements of
adenine can indeed produce highly potent compounds, more
potent indeed than the single ring imidazole derivative we
recently reported [108 nm].[12a] Additionally, we establish that
naphthalene-based surrogates, completely unrelated to natu-
ral purine nucleobases, are relatively well tolerated and that a
b-configuration is a prerequisite for potent adenophostin A-
like activity. We also demonstrate that the traditional
N-glycosidic linkage can be effectively replaced by a C-gly-
cosidic one. These biological results and the pharmacological
implications have been reported fully elsewhere.[19]
All trisphosphate targets were obtained and stored as the
‡
corresponding Na salt and accurately quantified by total
phosphate assay.
For all the modified compounds the EC50 of each was
evaluated for Ca2‡ mobilising ability in permeabilised hep-
atocytes relative to Ins(1,4,5)P3 [145 nm] and our synthetic
adenophostin A[19] [14.7 nm]. Uridophostin (12) was found to
be the most active compound [34 nm], followed by the
benzimidazole derivative 13 [48 nm], the b-4-methylanisolyl
derivative 15 [48 nm], the b-4-methylnaphthalenyl derivative
16 [62 nm] and the b-2-methoxynaphthalenyl derivative 14
Thus, we further demonstrate that the nucleobase motif of
adenophostin A can be replaced by both natural and un-
natural surrogates and still maintain the high activity of the
adenophostins. Our synthetic route to these modified com-
pounds is versatile and should facilitate the synthesis of a
range of further base-modified ligands, some with novel and
finely tuned activity at the Ins(1,4,5)P3 receptor.
Chem. Eur. J. 2001, 7, No. 22
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0722-4941 $ 17.50+.50/0
4941

B. V. L. Potter et al.
FULL PAPER
1,2-Di-O-acetyl-5-O-benzyl-3-O-(3,4-di-O-acetyl-2,6-di-O-benzyl-a-d-glu-
copyranosyl)-d-ribofuranose (20): A solution of 19 (141 mg, 0.2 mmol) in
aqueous TFA (90%, 3 mL) was stirred at room temperature for 5 min. The
solution was diluted with water and the mixture was concentrated under
reduced pressure. The resulting residue was partitioned between ethyl
acetate and 0.5n NaHCO3 and the organic layer was washed with brine,
dried (MgSO4) and concentrated yielding the corresponding cis-diol as a
non-isolated intermediate. Acetonitrile (3 mL) was added followed by
Ac2O (60 mL, 0.6 mmol) and DMAP (73 mg, 0.6 mmol) and the mixture
was stirred at room temperature for 30 min. Methanol was then added and
the solvent removed under reduced pressure. The resulting residue was
partitioned between chloroform and 0.5n HCl. The organic layer was
washed with brine, dried (MgSO4) and concentrated. The resulting crude
residue was purified by silica gel chromatography (hexane/ethyl acetate 5:1
then 3:1) yielding title compound as white solids (20, 119 mg, 80%) of
The synthesis of the C-glycosidic analogue of adenophos-
tin A and its uracil congener has recently been reported.[20]
We have also recently reported modifications to the pyranose
moiety of adenophostin A.[21]
Experimental Section
General methods: Chemicals were purchased from Aldrich, Fluka and
Sigma. Dry toluene and dichloromethane were distilled from calcium
hydride and stored over 4 Š molecular sieves. Acetonitrile was distilled
from phosphorous pentoxide and stored over 3 Š molecular sieves.
Pyridine was dried over potassium hydroxide pellets, distilled and then
stored over potassium hydroxide pellets. Molecular sieves (3 and 4 Š) were
pre-dried in an oven and activated for three hours under vacuum at 2508C.
Ether is diethyl ether. All aqueous (aq) solutions are saturated unless
otherwise stated. Reactions were carried out at room temperature under a
nitrogen atmosphere in pre-dried glassware unless otherwise stated.
Analytical thin-layer chromatography (TLC) was performed on pre-coated
plates (Merck TLC aluminium sheets, silica 60 F254, Art. No. 5554): the
products were visualised by UV radiation and staining with ethanolic
phosphomolybdic acid followed by heating. Column chromatography was
carried out under pressure on Sorbsil C60 silica gel. NMR spectra (31P, 1H,
13C) were recorded on either a JEOL GX270 or EX 400 or a Varian
Mercury 400 spectrometer with signals being assigned by 1D, DEPT, and
2D spectra (COSY, HETCOR, NOESY). Chemical shifts are quoted in
parts per million (ppm) relative to tetramethylsilane (TMS), deuterium
oxide (D2O), [D]chloroform (CDCl3), [D4]methanol (CD3OD). Coupling
1
which H NMR spectrum was in accord with the authentic compound.[12a]
2'-O-Acetyl-5'-O-benzyl-3'-O-(3,4-di-O-acetyl-2,6-di-O-benzyl-a-d-gluco-
pyranosyl)uridine (21):
A mixture of uracil (90 mg, 0.80 mmol) and
(NH4)2SO4 (4 mg) in N,N,N',N'-hexamethyldisilazane (1.0 mL) was heated
under reflux for 3 h. The solvent was evaporated under reduced pressure
and the residue was co-evaporated with toluene to give silylated uracil as a
non-purified residue. To a mixture of crude material and 20 (150 mg,
0.20 mmol) in acetonitrile (5 mL) was added TMSOTf (146 mL, 0.80 mmol)
at 08C and the resulting mixture was stirred at room temperature for 1 h.
The mixture was filtered through Celite with insoluble materials and Celite
being washed with ethyl acetate. The filtrate and collected washings were
combined, washed with NaHCO3 and brine, dried (MgSO4) and concen-
trated in vacuo. The crude residue was purified by silica gel chromatog-
raphy (hexane/ethyl acetate 2:1 to 1:1) providing 21 (150 mg, 93%).
1H NMR (400 MHz, CDCl3): d ˆ 8.70 (brs, 1H, NH), 7.74 (d, J ˆ 8.3, 1H,
H-6), 7.39 ± 7.24 (m, 15H, ArH), 6.18 (d, J ˆ 4.9, 1H, H-1'), 5.40 (dd, J ˆ 9.8,
10.3, 1H, H-3''), 5.40 (dd, J ˆ 2.5, 8.3, 1H, H-5), 5.19 (dd, J ˆ 4.9, 5.4, 1H,
H-2'), 5.01 (dd, J ˆ 9.5, 9.8, 1H, H-3''), 4.99 (d, J ˆ 3.4, 1H, H-1''), 4.64, 4.34
(AB, 2H, CH2Ph), 4.53 ± 4.40 (m, 6H, H-3', H-4', 2 Â CH2Ph), 3.92 (m, 1H,
H-5''), 3.76 (dd, J ˆ 2.0, 10.7, 1H, H-5'a), 3.65 (dd, J ˆ 1.5, 10.7, 1H, H-5'b),
3.55 (dd, J ˆ 3.4, 10.3, 1H, H-2''), 2.99 (m, 2H, H-6''), 1.96, 1.93, 1.89 (3  s,
3
constants are quoted in Hz and refer to JH,H unless otherwise stated. The
31P NMR shifts were measured in ppm relative to external 85% phosphoric
acid. Low-resolution mass spectra were recorded by the University of Bath
Mass Spectrometry Service using fast atom bombardment (FAB, ‡ve and -
ve) with 3-nitrobenzyl alcohol (NBA) as the matrix. High-resolution mass
spectrometry (HRMS) was also carried out by the University of Bath Mass
Spectrometry Service.
‡
9H, 3  OAc); HRMS-FAB:m/z: calcd for C42H47N2O14 803.3027 [M‡H] ,
found: 803.2969; UV (methanol): lmax ˆ 255 nm.
Free acids of final trisphosphates (12 ± 15, 15a) were converted into and
1-Benzimidazolyl-5-O-benzyl-3-O-(3,4-di-O-acetyl-2,6-di-O-benzyl-a-d-
‡
stored as the corresponding Na salt obtained by the following procedure:
glucopyranosyl)-b-d-ribofuranose (24):
A mixture of benzimidazole
the free acid was dissolved in water and applied to a Diaion WK-20 resin
(947 mg, 0.40 mmol) and (NH4)2SO4 (1 mg) in N,N,N',N'-hexamethyldisil-
azane (1.0 mL) was heated under reflux for 3 h. The solvent was evaporated
in vacuo and the residue was co-evaporated with toluene to give silylated
benzimidazole as a non-isolated residue. To a mixture of this residue and 20
(75 mg, 0.10 mmol) in acetonitrile (2 mL) was added SnCl4 (1.0m in
CH2Cl2, 400 mL, 0.40 mmol) at 08C and the resulting mixture was stirred at
room temperature for 1 h. The mixture was filtered through Celite and the
insoluble materials and Celite were washed with ethyl acetate. The filtrate
and washings were combined and washed with NaHCO3 and brine, dried
(MgSO4) and concentrated in vacuo. The resulting residue was purified by
silica gel chromatography (hexane/ethyl acetate 5:4 to 1:1) to give 25
‡
column (Na form) and developed with water. The eluent was evaporated
in vacuo and the residue was co-evaporated with ethanol to give the
corresponding sodium salt.
Total phosphate quantification was carried out using either a modified
Briggs test[22] or the Ames assay.
Mass spectra of target trisphosphates (12 ± 15, 15a) were obtained as the
corresponding triethylammonium salts prepared as follows: an aqueous
solution of the sodium salt of 12 ± 15, 16a was passed through a short
‡
column of Dowex 50 (H form, developed with water) and the eluent was
evaporated under reduced pressure. The resulting residue was dissolved in
0.5m triethylammonium bicarbonate buffer, which was evaporated in
vacuo to give the corresponding triethylammonium salts as solids.
1
(41 mg, 51%). H NMR (400 MHz, CDCl3): d ˆ 8.19 (s, 1H, H-2), 7.80 (d,
J ˆ 7.8, 1H, Hbenzimidazole), 7.64 (d, J ˆ 8.3, 1H, Hbenzimidazole), 7.39 ± 7.20 (m,
16H, Hbenzimidazole, ArH), 7.16 (dd, J ˆ 7.3, 7.8, 1H, Hbenzimidazole), 6.15 (d, J ˆ
6.4, 1H, H-1'), 5.47 (dd, J ˆ 9.8, 10.2, 1H, H-3''), 5.38 (dd, J ˆ 5.9, 6.4, 1H,
H-2'), 5.02 (dd, J ˆ 9.8, 9.8, 1H, H-4''), 4.91 (d, J ˆ 3.9, 1H, H-1''), 4.65 (dd,
J ˆ 3.4, 5.9, 1H, H-3'), 4.63 ± 4.36 (m, 7H, H-4', 3  CH2Ph), 4.01 (m, 1H,
H-5''), 3.69 (dd, J ˆ 2.4, 10.7, 1H, H-5'a), 3.66 (dd, J ˆ 2.0, 10.7, 1H, H-5'b),
3.55 (dd, J ˆ 3.9, 10.2, 1H, H-2''), 3.99 (d, J ˆ 3.9, 2H, H-6''), 2.00, 1.95, 1.85
(3 Â s, 9 H, 3 Â OAc); HRMS-FAB: m/z: calcd for C45H49N2O12: 809.3286
3,4-Di-O-acetyl-2,6-di-O-benzyl-d-glucopyranose (18): A mixture of 17[12a]
(400 mg, 1 mmol), DMAP (366 mg, 3 mmol) and Ac2O (300 mL, 3 mmol) in
acetonitrile (15 mL) was stirred at room temperature for 1 h. Methanol was
added and the solvent was evaporated under reduced pressure with the
resulting residue being partitioned between chloroform and 0.5n HCl. The
organic layer was washed with brine, dried (MgSO4) and evaporated under
reduced pressure. The residue was purified by silica gel chromatography
(hexane/ethyl acetate 10:1 then 5:1) to give allyl 3,4-di-O-acetyl-2,6-di-O-
benzyl-a-d-glucopyranose as an oil (490 mg, quant.). The oil was then
dissolved in methanol/dichloromethane (1:1, 6 mL) to which PdCl2 (34 mg,
0.2 mmol) was added. The resulting mixture was stirred at 10 ± 208C for
18 h after which the solution was filtered through Celite and the resulting
filtrate was evaporated under reduced pressure. The resulting residue was
then partitioned between chloroform and brine with the organic layer being
dried (MgSO4) and concentrated. The crude residue was purified by silica
gel chromatography (hexane/ethyl acetate 5:1 then 3:1) yielding the title
compound as white solids (18, 412 mg, 93%). 1H NMR spectrum was in
accord with that of previously reported compound.[12a]
‡
[M‡H] , found: 809.3321.
2-O-Acetyl-5-O-benzyl-1-(2-methoxynaphthalenyl)-3-O-(3,4-di-O-acetyl-
2,6-di-O-benzyl-a-d-glucopyranosyl)-d-ribofuranose (27): SnCl4 (94 mL,
0.80 mmol) was added at room temperature to a mixture of 20 (300 mg,
0.40 mmol), 2-methoxynaphthalene (1.27 g, 8.0 mmol) and AgCO2CF3
(132 mg, 0.60 mmol) in chloroform and the resulting mixture was stirred
at room temperature for 45 min. NaHCO3 was added and the mixture was
stirred at room temperature for an additional 5 min. The mixture was
filtered though Celite and the insoluble materials and Celite was washed
with chloroform. The filtrate and washings were combined and washed with
brine, dried (MgSO4) and concentrated in vacuo. The resulting residue was
4942
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0722-4942 $ 17.50+.50/0
Chem. Eur. J. 2001, 7, No. 22

Adenophostin A Mimics
4937±4946
purified by silica gel chromatography (hexane/ethyl acetate 4:1 to 3:1)
yielding title compound as a syrup (27, 233 mg, 73%, a/b ratio was 15:85
based on 1H NMR analysis). 1H NMR (400 MHz, CDCl3): d ˆ 8.63 (d, J ˆ
8.5, 0.15H, Hnaphthalenea), 8.32 (d, J ˆ 8.6, 0.85H, Hnaphthaleneb), 7.82 (d, J ˆ 8.9,
0.85H, Hnaphthaleneb), 7.78 ± 7.68 (m, 1.15H, 2 Â Hnaphthalenea, Hnaphthaleneb), 7.53
(m, 1H, Hnaphthalenea, Hnaphthaleneb), 7.34 ± 7.18 (m, 17H, ArH, 2 Â Hnaphthalenea,
2  Hnaphthaleneb), 6.21 (d, J ˆ 2.8, 0.15H, H-1'a), 5.94 (d, J ˆ 7.3, 0.85H,
H-1'b), 5.81 (dd, J ˆ 2.8, 4.1, 0.15H, H-2'a), 5.64 (dd, J ˆ 7.0, 7.3, 0.85H,
H-2'b), 5.51 (dd, J ˆ 9.5, 10.0, 0.85H, H-3''b), 5.44 (dd, J ˆ 9.8, 9.8, 0.15H,
H-3''a), 5.15 (dd, J ˆ 4.3, 8.9, 0.15H, H-4''a), 5.11 ± 5.03 (m, 1.7H, H-1''b,
H-4''b), 4.91 (d, J ˆ 4.3, 0.15H, H-1''a), 4.70 ± 3.82 (m, 14H, 3  CH2Ph,
H-3', H-4', H-5', H-5'', OCH3), 3.60 ± 3.31 (m, 3H, H-2'', H-6''), 2.17, 1.97,
1-Benzimidazolyl-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-
b-d-ribofuranose (25): NaOMe (catalytic quantity) was added to a solution
of 24 (65 mg, 0.4 mmol) in methanol (3 mL) and the solution was stirred at
room temperature for 3 h. The mixture was neutralised with 1m AcOH (in
THF) and concentrated in vacuo. The resulting residue was partitioned
between chloroform and brine, separated, and the organic layer was dried
(MgSO4) and evaporated under reduced pressure. The crude residue was
purified by silica gel chromatography (chloroform/methanol 60:1 to 40:1)
yielding title compound as a yellow syrup (25, 48 mg, 87%). 1H NMR
(400 MHz, CDCl3): d ˆ 8.08 (s, 1H, H-2), 7.75 (d, J ˆ 8.2, 1H, Hbenzimidazole),
7.58 (d, J ˆ 8.2, 1H, Hbenzimidazole), 7.36 ± 7.21 (m, 16H, Hbenzimidazole, ArH), 7.09
(dd, J ˆ 7.6, 7.6, 1H, Hbenzimidazole), 5.76 (d, J ˆ 6.1, 1H, H-1'), 4.87 (d, J ˆ 3.7,
1H, H-1''), 4.77, 4.67 (AB, 2H, CH2Ph), 4.55 ± 4.45 (m, 5H, H-2', 2 Â
CH2Ph), 4.30 ± 4.26 (m, 2H, H-3', H-4'), 4.03 (dd, J ˆ 9.2, 9.5, 1H, H-3''),
3.85 (m, 1H, H-5''), 3.71 ± 3.52 (m, 5H, H-5', H-4'', H-6''), 3.47 (dd, J ˆ 3.7,
1.92, 1.88, 1.85 (5 Â s, 9 H, 3 Â OAc); HRMS-FAB: m/z: calcd for C49H53O13
:
‡
849.3486 [M‡H] , found: 849.3462.
2-O-Acetyl-5-O-benzyl-1-(4-methylanisol-2-yl)-3-O-(3,4-di-O-acetyl-2,6-
‡
9.5, 1H, H-2''); HRMS-FAB: m/z: calcd for C39H43N2O9: 683.2969 [M‡H] ,
di-O-benzyl-a-d-glucopyranosyl)-d-ribofruanose (30): SnCl4 (94 mL,
0.80 mmol) was added at room temperature to a mixture of 20 (300 mg,
0.40 mmol), 4-methylanisole (977 mg, 8.0 mmol) and AgCO2CF3 (132 mg,
0.60 mmol) in chloroform and the resulting mixture was stirred at room
temperature for 45 min. NaHCO3 was added and the mixture was stirred at
room temperature for an additional 5 min. The mixture was filtered though
Celite and the insoluble materials and Celite were washed with chloroform.
The filtrate and washings were combined and washed with brine, dried
(MgSO4) and concentrated in vacuo. The resulting residue was purified by
silica gel chromatography (hexane/ethyl acetate 5:1 to 3:1) yielding title
compound as a syrup (30, 217 mg, 67%, a/b 1:1 based on 1H NMR
analysis). 1H NMR (400 MHz, CDCl3): d ˆ 7.39 ± 7.16 (m, 16H, ArH,
found: 683.2967.
5-O-Benzyl-1-(2-methoxynaphthalenyl)-3-O-(2,6-di-O-benzyl-a-d-gluco-
pyranosyl)-b-d-ribofuranose and 5-O-benzyl-1-(2-methoxynaphthalenyl)-
3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-a-d-ribofuranose (28 and 28a):
NaOMe (catalytic quantity) was added to a solution of 27 (340 mg,
0.4 mmol) in methanol (3 mL) and the solution was stirred at room
temperature for 3 h. The mixture was neutralised with 1m AcOH (in THF)
and concentrated in vacuo. The resulting residue was partitioned between
chloroform and brine, separated, and the organic layer was dried (MgSO4)
and evaporated under reduced pressure. The crude residue was purified by
silica gel chromatography (chloroform/acetone 60:1 to 50:1) yielding 5-O-
benzyl-1-(2-methoxynaphthalenyl)-3-O-(2,6-di-O-benzyl-a-d-glucopyra-
nosyl)-b-d-ribofuranose as a yellow syrup (28, 235 mg, 81%). 1H NMR
(400 MHz, CDCl3): d ˆ 8.34 (d, J ˆ 8.3, 1H, H-8), 7.79 (d, J ˆ 8.8, 1H, H-4),
7.74 (d, J ˆ 8.3, 1H, H-5), 7.34 ± 7.23 (m, 16H, H-6, ArH), 7.25 (d, J ˆ 8.8,
1H, H-3), 7.18 (dd, J ˆ 7.3, 8.3, 1H, H-7), 5.70 (d, J ˆ 7.3, 1H, H-1'), 4.94 (d,
J ˆ 3.4, 1H, H-1''), 4.76 ± 4.48 (m, 7H, H-2', CH2Ph), 4.44 (dd, J ˆ 5.9, 5.9,
1H, H-3'), 4.18 (m, 1H, H-4'), 4.03 (dd, J ˆ 9.3, 9.3, 1H, H-3''), 3.91 ± 3.59
(m, 5H, H-5', H-5'', H-6''), 3.84 (s, 3H, OMe), 3.56 (dd, J ˆ 9.3, 9.3, 1H,
H
anisolyl), 7.05 (dd, J ˆ 1.8, 8.2, 0.5H, Hanisolyl), 6.99 (dd, J ˆ 1.8, 8.2, 0.5H,
Hanisolyl), 6.77 (d, J ˆ 8.2, 0.5H, Hanisolyl), 6.67 (d, J ˆ 8.2, 0.5H, Hanisolyl), 5.84
(dd, J ˆ 3.4, 3.7, 0.5H, H-2'b), 5.48 (d, J ˆ 3.1, 0.5H, H-2'a), 5.43 ± 5.36 (m,
1H, H-1'a, H-3''b), 5.27 (d, J ˆ 3.1, 0.5H, H-3''a), 5.14 (d, J ˆ 3.7, 0.5H,
H-1'b), 5.08 ± 5.03 (m, 1H, H-4''), 4.75 ± 4.12 (m, 9H, 3 Â CH2Ph, H-1'', H-3',
H-5''), 3.97 ± 3.73 (m, 6H, H-4', H-5', OCH3), 3.58 ± 3.51 (m, 1H, H-2''),
3.35 ± 3.12 (m, 2H, H-6''), 2.27, 2.18, 2.04, 1.91, 1.88, 1.87, 1.86 (7 Â s, 12H,
CH3Ph, 3 Â OAc); HRMS-FAB: m/z: calcd for C46H53O12
: 813.3486
‡
[M‡H] , found: 813.3486.
H-4''), 3.43 (dd, J ˆ 3.4, 9.3, 1H, H-2''); HRMS-FAB: m/z: calcd for
‡
C43H46O10
:
722.3091 [M‡H] , found: 722.3097; and 5-O-benzyl-1-(2-
2-O-Acetyl-5-O-benzyl-1-(4-methylnaphthalenyl)-3-O-(3,4-di-O-acetyl-
2,6-di-O-benzyl-a-d-glucopyranosyl)-d-ribofruanose (33): SnCl4 (94 mL,
0.80 mmol) was added at room temperature to a mixture of 20 (300 mg,
0.40 mmol), 1-methylnaphthalene (1.14 g, 8.0 mmol) and AgCO2CF3
(132 mg, 0.60 mmol) in chloroform and the resulting mixture was stirred
at room temperature for 45 min. NaHCO3 was added and the mixture was
stirred at room temperature for an additional 5 min. The mixture was
filtered though Celite and the insoluble materials and Celite was washed
with chloroform. The filtrate and washings were combined and washed with
brine, dried (MgSO4) and concentrated in vacuo. The resulting residue was
purified by silica gel chromatography (hexane/ethyl acetate 4:1 to 3:1)
yielding title compound as a syrup (33, 152 mg, 46%, a/b ratio was 35:65
based on 1H NMR analysis). 1H NMR (400 MHz, CDCl3): d ˆ 8.04 ± 7.20
(m, 21H, ArH, Hnaphthalenyl), 5.97 ± 5.53 (m, 1H, H-2'), 5.52 ± 5.34 (m, 2H,
H-1', H-3''), 5.15 ± 4.87 (m, 3H, H-3', H-1'', H-4''), 4.67 ± 4.22 (m, 8H, 3 Â
CH2Ph, H-4', H-5''), 3.95 ± 3.74 (m, 2H, H-5'), 3.58 ± 3.51 (m, 1H, H-2''),
3.40 ± 3.24 (m, 2H, H-6''), 2.69, 2.67 (2 Â s, 3 H, CH3Ph), 1.98, 1.95, 1.92, 1.89
methoxynaphthalenyl)-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-a-d-ri-
bofuranose (28a, 15 mg, 5%): 1H NMR (400 MHz, CDCl3): d ˆ 8.57 (d, J ˆ
8.8, 1H, Hnaphthalene), 7.81 (d, J ˆ 9.3, 1H, Hnaphthalene), 7.73 (d, J ˆ 8.3, 1H,
H
naphthalene), 7.42 (dd, J ˆ 8.3, 8.8, 1H, Hnaphthalene), 7.34 ± 7.29 (m, 17H, 2 Â
Hnaphthalene, 3  CH2Ph), 6.06 (d, J ˆ 3.4, 1H, H-1'), 4.93 (d, J ˆ 3.4, 1H,
H-1''), 4.72 ± 4.51 (m, 8H, H-2', H-3', 3  CH2Ph), 3.98 (dd, J ˆ 9.3, 9.3, 1H,
H-3''), 3.94 (s, 3H, OMe), 3.87 ± 3.56 (m, 7H, H-4', H-5', H-4'', H-5'', H-6''),
3.38 (dd, J ˆ 3.4, 9.3, 1H, H-2''); HRMS-FAB: m/z: calcd for C43H46O10
:
‡
722.3091 [M‡H] , found: 722.3089.
5-O-Benzyl-1-(4-methylanisol-2-yl)-3-O-(2,6-di-O-benzyl-a-d-glucopyra-
nosyl)-b-d-ribofuranose and 5-O-benzyl-1-(4-methylanisol-2-yl)-3-O-(2,6-
di-O-benzyl-a-d-glucopyranosyl)-a-d-ribofuranose (31 and 31a): NaOMe
(catalytic quantity) was added to a solution of 30 (230 mg, 0.25 mmol) in
methanol (3 mL) and the solution was stirred at room temperature for 3 h.
The mixture was neutralised with 1m AcOH (in THF) and concentrated in
vacuo. The resulting residue was partitioned between chloroform and
brine, separated, and the organic layer was dried (MgSO4) and evaporated
under reduced pressure. The crude residue was purified by silica gel
chromatography (chloroform/acetone 30:1 to 20:1) yielding 5-O-benzyl-1-
(4-methylanisol-2-yl)-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-b-d-ribo-
furanose as a yellow syrup (31, 66 mg, 38%). 1H NMR (400 MHz, CDCl3):
d ˆ 7.37 ± 7.27 (m, 16H, H-3, ArH), 7.03 (dd, J ˆ 2.1, 8.2, 1H, H-5), 6.76 (d,
J ˆ 8.2, 1H, H-6), 5.18 (d, J ˆ 4.9, 1H, H-1'), 4.85 (d, J ˆ 3.7, 1H, H-1''),
4.77 ± 4.43 (m, 6H, 3  CH2Ph), 4.25 ± 4.20 (m, 2H, H-3', H-4'), 4.12 (dd, J ˆ
4.9, 4.9, 1H, H-2'), 3.98 (dd, J ˆ 9.2, 9.2, 1H, H-3''), 3.82 ± 3.52 (m, 6H, H-5',
H-4'', H-5'', H-6''), 3.77 (s, 3H, OMe), 3.40 (dd, J ˆ 3.7, 9.2, 1H, H-2''), 2.18
(4 Â s, 9H, OAc); HRMS-FAB: m/z: calcd for C49H53O12
:
833.3537
‡
[M‡H] , found: 833.3496.
5-O-Benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)uridine
(22):
NaOMe (cat) was added to a solution of 21 (71 mg, 0.9 mmol) in methanol
(3 mL) and the solution was stirred at room temperature for 3 h. The
mixture was neutralised with 1m AcOH (in THF) and concentrated in
vacuo. The resulting residue was partitioned between chloroform and
brine, separated, and the organic layer was dried (MgSO4) and evaporated
under reduced pressure. The crude residue was purified by silica gel
chromatography (chloroform/methanol 30:1) yielding title compound (22,
solids, 54 mg, 88%). 1H NMR (400 MHz, CDCl3): d ˆ 9.84 (brs, 1H, NH),
7.61 (d, J ˆ 7.8, 1H, H-6), 7.36 ± 7.21 (m, 15H, ArH), 6.10 (d, J ˆ 6.8, 1H,
H-1'), 5.39 (d, J ˆ 7.8, 1H, H-5), 4.86 (d, J ˆ 3.4, 1H, H-1''), 4.75, 4.70 (AB,
2H, CH2Ph), 4.53 ± 4.29 (m, 5-H, H-4', 2 Â CH2Ph), 4.15 (m, 1H, H-2'),
4.06 ± 4.00 (m, 2H, H-3', H-3''), 3.93 (brs, 1H, OH), 3.85 (m, 1H, H-5''), 3.72
(d, J ˆ 8.8, 1H, H-6''a), 3.61 ± 3.43 (m, 5H, H-5', H-2'', H-4'', H-6''b), 2.19
(brs, 2H, 2 Â OH); HRMS-FAB: m/z: calcd for C36H41N2O11: 677.2710
‡
(s, 3H, Me); HRMS-FAB: m/z: calcd for C40H45O10: 685.3013 [M‡H] ,
found: 685.3017; and 5-O-benzyl-1-(4-methylanisol-2-yl)-3-O-(2,6-di-O-
benzyl-a-d-glucopyranosyl)-a-d-ribofuranose
(31a,
61 mg,
36%):
1H NMR (400 MHz, CDCl3): d ˆ 7.40 (d, J ˆ 1.8, 1H, H-3), 7.36 ± 7.27 (m,
15H, ArH), 7.05 (dd, J ˆ 1.8, 8.2, 1H, 5-H), 6.76 (d, J ˆ 8.2, 1H, H-6), 5.36
(d, J ˆ 2.4, 1H, H-1'), 4.83 (d, J ˆ 3.7, 1H, H-1''), 4.71 ± 4.46 (m, 7H, H-2',
3  CH2Ph), 4.36 (m, 1H, H-3'), 3.90 (dd, J ˆ 9.1, 9.5, 1H, H-3''), 3.82 (s, 3H,
OMe), 3.78 ± 3.51 (m, 7H, H-4', H-5', H-4'', H-5'', H-6''), 3.35 (dd, J ˆ 3.7,
‡
[M‡H] , found: 677.2726.
Chem. Eur. J. 2001, 7, No. 22
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0722-4943 $ 17.50+.50/0
4943

B. V. L. Potter et al.
FULL PAPER
9.5, 1H, H-2''), 3.05, 2.56, 2.54 (3 Â brs, 3 Â 1H, 3 Â OH), 2.31 (s, 3H, Me);
1-(2-Methoxynaphthalenyl)-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-gluco-
pyranosyl)-b-d-ribofuranose 2',3'',4''-tris(dibenzylphosphate) (29): Diben-
‡
HRMS-FAB: m/z: calcd for C40H46O10: 686.3091 [M‡H] , found: 686.3093.
zyl(diisopropyl)phosphoramidite (42 mL, 0.13 mmol) was added to
a
5-O-Benzyl-1-(4-methylnaphthalenyl)-3-O-(2,6-di-O-benzyl-a-d-glucopyr-
anosyl)-b-d-ribofuranose and 5-O-benzyl-1-(4-methylnaphthalenyl)-3-O-
(2,6-di-O-benzyl-a-d-glucopyranosyl)-a-d-ribofuranose (34 and 34a):
NaOMe (catalytic quantity) was added to a solution of 33 (42 mg,
0.05 mmol) in methanol (3 mL) and the solution was stirred at room
temperature for 3 h. The mixture was neutralised with 1m AcOH (in THF)
and concentrated in vacuo. The resulting residue was partitioned between
chloroform and brine, separated, and the organic layer was dried (MgSO4)
and evaporated under reduced pressure. The crude residue was purified by
silica gel chromatography yielding 5-O-benzyl-1-(4-methylnaphthalenyl)-
3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-b-d-ribofuranose as a yellow
syrup (34, 20 mg, 57%). 1H NMR (400 MHz, CDCl3): d ˆ 8.20 (dd, J ˆ
1.8, 7.6, 1H, Hnaphthalene), 8.04 (dd, J ˆ 1.8, 7.4, 1H, Hnaphthalene), 7.65 (d, J ˆ 7.4,
1H, Hnaphthalene), 7.57 ± 7.49 (m, 2H, 2 Â Hnaphthalene), 7.37 ± 7.23 (m, 16H, ArH,
solution of 5-O-benzyl-1-(2-methoxynaphthalenyl)-3-O-(2,6-di-O-benzyl-
a-d-glucopyranosyl)-b-d-ribofuranose (28, 181 mg, 0.025 mmol) and 1H-
tetrazole (18 mg, 0.25 mmol) in dichloromethane and the mixture stirred at
room temperature for 3 h. The solution was cooled to 788C and mCPBA
(38 mg, 0.13 mmol) was added with stirring continuing for an additional 2 h
at room temperature. The mixture was diluted with ethyl acetate and was
washed with 10% Na2SO3, 1n HCl, 0.5n NaHCO3, brine, dried (MgSO4)
and evaporated under reduced pressure. The resulting crude residue was
purified by silica gel chromatography (hexane/ethyl acetate 2:1 to 1:1)
yielding title compound as a syrup (29, 345 mg, 92%). 1H NMR (400 MHz,
CDCl3): d ˆ 8.32 (d, J ˆ 8.8, 1H, Hnaphthalene), 7.77 (d, J ˆ 8.8, 1H, Hnaphthalene),
7.72 (d, J ˆ 7.3, 1H, Hnaphthalene), 7.43 ± 6.65 (m, 48H, 3  Hnaphthalene, ArH),
6.10 (d, J ˆ 7.3, 1H, H-1'), 5.65 (m, 1H, H-2'), 5.56 (d, J ˆ 3.4, 1H, H-1''),
5.07 ± 4.62 (m, 12H, 5 Â CH2Ph, H-3'', H-4''), 4.53 ± 4.01 (m, 9H, 4 Â CH2Ph,
H-3'), 3.90 ± 3.56 (m, 7H, H-4', H-5', H-2'', H-5'', H-6''), 3.68 (s, 3H, OMe);
31P NMR (100 MHz, CDCl3, H-decoupled): d ˆ 1.49, 2.28, 2.30 (3  s,
H
naphthalene), 5.57 (d, J ˆ 3.5, 1H, H-1'), 4.74, 4.69 (AB, 2H, CH2Ph), 4.71 (d,
J ˆ 4.0, 1H, H-1''), 4.64, 4.56 (AB, 2H, CH2Ph), 4.54, 4.45 (AB, 2H,
CH2Ph), 4.35 ± 4.32 (m, 1H, H-3'), 4.24 ± 4.17 (m, 2H, H-2', OH), 4.00 (t,
J ˆ 9.4, 1H, H-3''), 3.88 ± 3.73 (m, 5H, H-4', H-5', H-5'', OH), 3.62 ± 3.51 (m,
4H, H-4'', H-6'', OH), 3.4 (dd, J ˆ 3.5, 9.7, 1H, H-2''), 2.52 (s, 3H, CH3Ph);
and 5-O-benzyl-1-(4-methylnaphthalenyl)-3-O-(2,6-di-O-benzyl-a-d-glu-
copyranosyl)-a-d-ribofuranose (34a, 11 mg, 31%): 1H NMR (400 MHz,
CDCl3): d ˆ 8.02 (m, 1H, Hnaphthalene), 7.88 (m, 1H, Hnaphthalene), 7.73 (d, J ˆ
7.4, 1H, Hnaphthalene), 7.52 (m, 2H, 2  Hnaphthalene), 7.37 (d, J ˆ 7.4, 1H,
Hnaphthalene), 7.36 ± 7.16 (m, 15H, ArH), 5.88 (d, J ˆ 3.1, 1H, H-1'), 4.78 (d,
J ˆ 3.9, 1H, H-1''), 4.61 ± 4.28 (m, 9H, 3  CH2Ph, H-2', H-3', OH), 3.86 (t,
J ˆ 9.0, 1H, H-3''), 3.82 ± 3.76 (m, 2H, H-5'), 3.70 ± 3.53 (m, 6H, H-4', H-4'',
H-5'', H-6'', OH), 3.33 (dd, J ˆ 3.75, 9.7, 1H, H-2''), 3.1 (brs, 1H, OH), 2.41
(s, 3H, CH3Ph).
‡
3  P); HRMS-FAB: m/z: calcd for C85H86O19P3: 1503.4976 [M‡H] ,
found: 1503.5016.
1-(4-Methylanisol-2-yl)-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyra-
nosyl)-b-d-ribofuranose 2',3'',4''-tris(dibenzylphosphate) (32): Dibenzyl-
(diisopropyl)phosphoramidite (42 mL, 0.13 mmol) was added to a solution
of 5-O-benzyl-1-(4-methylanisol-2-yl)-3-O-(2,6-di-O-benzyl-a-d-glucopyr-
anosyl)-b-d-ribofuranose (31, 38 mg, 0.055 mmol) and 1H-tetrazole
(18 mg, 0.25 mmol) in dichloromethane and the mixture stirred at room
temperature for 3 h. The solution was cooled to 788C and mCPBA
(38 mg, 0.13 mmol) was added with stirring continuing for an additional 2 h
at 208C. The mixture was diluted with ethyl acetate and was washed with
10% Na2SO3, 1n HCl, 0.5n NaHCO3, brine, dried (MgSO4) and
evaporated under reduced pressure. The crude residue was purified by
silica gel chromatography (hexane/ethyl acetate 2:1 to 1:1) yielding title
5-O-Benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)uridine
2',3'',4''-
tris(dibenzylphosphate) (23): Dibenzyl(diisopropyl)phosphoramidite
(42 mL, 0.13 mmol) was added to a solution of 5-O-Benzyl-3-O-(2,6-di-O-
benzyl-a-d-glucopyranosyl)uridine (22, 19 mg, 0.028 mmol) and 1H-tetra-
zole (18 mg, 0.25 mmol) in dichloromethane (1 mL) and the mixture was
stirred at room temperature for 3 h. To this mixture was then added
mCPBA (38 mg, 0.13 mmol) at 788C and the resulting mixture was
stirred at room temperature for an additional 2 h. The reaction mixture was
diluted with ethyl acetate and washed with aq. 10% Na2SO3, 1n HCl, 0.5n
NaHCO3 and brine, dried (MgSO4) and concentrated in vacuo. The
resulting crude residue was purified by silica gel chromatography (chloro-
form/methanol 50:1) to give title compound (23, 33 mg, 85%, isolated as
solid). 1H NMR (400 MHz, CDCl3): d ˆ 8.12 (brs, 1H, NH), 7.52 (d, J ˆ 8.3,
1H, H-6), 7.38 ± 7.06 (m, 45H, ArH), 6.35 (d, J ˆ 6.4, 1H, H-1'), 5.31 (d, J ˆ
3.4, 1H, H-1''), 5.31 (d, J ˆ 8.3, 1H, H-5), 5.04 ± 4.69 (m, 15H, H-2', H-3'',
H-4'', 6 Â CH2PH), 4.49 ± 4.21 (m, 8H, H-3', H-4', 3 Â CH2Ph), 3.80 ± 3.47
(m, 6H, H-5', H-2'', H-5'', H-6''); 31P NMR (67.5 MHz, CDCl3, H-decou-
pled): d ˆ 0.34, 1.17, 1.29 (3  s, 3  P); HRMS-FAB: m/z: calcd for
1
compound as a syrup (32, 78 mg, 96%). H NMR (400 MHz, CDCl3): d ˆ
7.39 ± 7.05 (m, 46H, H-2, ArH), 7.01 (dd, J ˆ 2.0, 8.3, 1H, H-5), 6.70 (d, J ˆ
8.3, 1H, H-6), 5.48 (d, J ˆ 5.4, 1H, H-1'), 5.31 (d, J ˆ 3.4, 1H, H-1''), 5.10 (m,
1H, H-2'), 5.04 ± 4.88 (m, 8H, 3 Â CH2Ph, H-3'', H-4''), 4.79 ± 4.57 (m, 6H,
3 Â CH2Ph), 4.51 ± 4.24 (m, 7H, 3 Â CH2Ph, H-3'), 3.85 ± 3.50 (m, 7H, H-4',
H-5', H-2'', H-5'', H-6''), 3.63 (s, 3H, OMe), 2.11 (s, 3H, Me); 31P NMR
(67.5 MHz, CDCl3, H-decoupled): d ˆ 1.10, 1.23, 1.38 (3  s, 3  P);
‡
HRMS-FAB: m/z: calcd for C82H86O19P3: 1467.4976 [M‡H] , found:
1467.5018.
1-(4-Methylanisol-2-yl)-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyra-
nosyl)-a-d-ribofuranose 2',3'',4''-tris(dibenzylphosphate) (32a): Dibenzyl-
(diisopropyl)phosphoramidite (42 mL, 0.13 mmol) was added to a solution
of 5-O-benzyl-1-(4-methylanisol-2-yl)-3-O-(2,6-di-O-benzyl-a-d-glucopyr-
anosyl)-a-d-ribofuranose (31a, 58 mg, 0.085 mmol) and 1H-tetrazole
(18 mg, 0.25 mmol) in dichloromethane and the mixture stirred at room
temperature for 3 h. The solution was cooled to 788C and mCPBA
(38 mg, 0.13 mmol) was added with stirring continuing for an additional 2 h
at 208C. The mixture was diluted with ethyl acetate and was washed with
10% Na2SO3, 1n HCl, 0.5n NaHCO3, brine, dried (MgSO4) and
evaporated under reduced pressure. The crude residue was purified by
silica gel chromatography yielding title compound as a syrup (32a, 108 mg,
87%). 1H NMR (400 MHz, CDCl3): d ˆ 7.42 ± 6.92 (m, 46H, H-5, ArH),
7.36 (d, J ˆ 2.0, 1H, H-3), 6.58 (d, J ˆ 8.3, 1H, H-6), 5.38 ± 5.35 (m, 3H, H-1',
H-2', H-1''), 5.06 ± 4.15 (m, 21H, 9 Â CH2Ph, H-3', H-3'', H-4''), 3.98 ± 3.59
(m, 7H, H-4', H-5', H-2'', H-5'', H-6''), 3.72 (s, 3H, OMe), 2.21 (s, 3H, Me);
31P NMR (67.5 MHz, CDCl3, H-decoupled): d ˆ 1.07, 1.29, 1.47 (3  s,
‡
C78H80N2O20P3: 1457.4517 [M‡H] , found: 1457.4565; UV (methanol):
lmax ˆ 257, 260 nm (sh).
1-Benzimidazolyl-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-
b-d-ribofuranose 2',3'',4''-tris(dibenzylphosphate) (26): Dibenzyl(diisopro-
pyl)phosphoramidite (42 mL, 0.13 mmol) was added to a solution of
1-benzimidazolyl-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-
b-d-ribofuranose (25, 48 mg, 0.07 mmol) and 1H-tetrazole (18 mg,
0.25 mmol) in dichloromethane and the mixture stirred at room temper-
ature for 3 h. The solution was cooled to 788C and mCPBA (38 mg,
0.13 mmol) was added with stirring continuing for an additional 2 h at
208C. The mixture was diluted with ethyl acetate and was washed with
10% Na2SO3, 1n HCl, 0.5n NaHCO3, brine, dried (MgSO4) and
evaporated under reduced pressure. Crude residue was purified by silica
gel chromatography (chloroform/acetone 200:1 to 100:1) yielding title
‡
3  P); HRMS-FAB: m/z: calcd for C82H86O19P3: 1467.4976 [M‡H] ,
found: 1467.4979.
1-(4-Methylnaphthalenyl)-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyr-
anosyl)-b-d-ribofuranose 2',3'',4''-tris(dibenzylphosphate) (35): Dibenzyl-
(diisopropyl)phosphoramidite (21 mL, 0.07 mmol) was added to a solution
of 1-(4-methylnaphthalenyl)-5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-gluco-
pyranosyl)-b-d-ribofuranose (34, 12 mg, 0.017 mmol) and 1H-tetrazole
(9 mg, 0.12 mmol) in dichloromethane (4 mL) and the reaction was stirred
at room temperature for 2 h. The solution was cooled to 788C and
mCPBA (19 mg, 0.07 mmol) was added with stirring continuing for an
additional 2 h. The mixture was diluted with ethyl acetate and was washed
with 10% Na2SO3, 1n HCl, 0.5n NaHCO3, brine, dried (MgSO4) and
1
compound as a syrup (26, 81 mg, 79%). H NMR (400 MHz, CDCl3): d ˆ
7.99 (s, 1H, H-2), 7.76 (d, J ˆ 8.2, 1H, Hbenzimidazole), 7.54 (d, J ˆ 8.3, 1H,
Hbenzimidazole), 7.35 ± 6.91 (m 47H, 2  Hbenzimidazole, ArH), 6.11 (d, J ˆ 6.8, 1H,
H-1'), 5.36 (d, J ˆ 3.4, 1H, H-1''), 5.26 (m, 1H, H-2'), 5.05 ± 4.89 (m, 8H,
H-3'', H-4'', 3 Â CH2Ph), 4.80 ± 4.70 (m, 2H, CH2Ph), 4.55 ± 4.29 (m, 11H,
H-3', 5 Â CH2Ph), 3.85 (m, 1H, H-4'), 3.74 ± 3.53 (m, 6H, H-5', H-2'', H-5'',
H-6''); 31P NMR (100 MHz, CDCl3, H-decoupled): d ˆ 1.73,
2.07,
2.18 (3 Â s, 3 Â P); HRMS-FAB: m/z: calcd for C81H82N2O18P3: 1463.4776
‡
[M‡H] , found: 1463.4743.
4944
ꢀ WILEY-VCH Verlag GmbH, D-69451 Weinheim, 2001
0947-6539/01/0722-4944 $ 17.50+.50/0
Chem. Eur. J. 2001, 7, No. 22

Adenophostin A Mimics
4937±4946
‡
evaporated under reduced pressure. The crude residue was purified by
silica gel chromatography yielding title compound as a syrup (35, 15 mg,
62%). 1H NMR (400 MHz, CDCl3): d ˆ 8.24 (d, J ˆ 8.6, 1H, Hnaphthalene),
7.94 (d, J ˆ 8.6, 1H, Hnaphthalene), 7.68 (d, J ˆ 7.4, 1H, Hnaphthalene), 7.51 ± 6.80
(m, 48H, 3  Hnaphthalene, ArH), 5.90 (d, J ˆ 7.0, 1H, H-1'), 5.42 (d, J ˆ 3.5,
1H, H-1''), 5.08 ± 4.26 (m, 22H, 9 Â CH2Ph, H-2', H-5'a, H-3'', H-4''), 3.89 ±
3.55 (m, 7 h, H-4', H-5'b, H-2'', H-5'', H-6''), 2.21 (s, 3H, CH3Ph); 31P NMR
(100 MHz, CDCl3, H-decoupled): d ˆ 0.87, 1.06, 1.32 (3  s, 3  P).
and applied to a Diaion WK-20 resin column (Na form), which was
developed with water. The eluent was evaporated under reduced pressure
and the residue was co-evaporated with ethanol to give the sodium salt of
1-(4-methylanisol-2-yl)-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose
1
2',3'',4''-trisphosphate (15, 19 mg, 80%). H NMR (400 MHz, CDCl3): d ˆ
7.16 (s, 1H, H-3), 7.08 (d, J ˆ 8.2, 1H, H-5), 6.84 (d, J ˆ 8.2, 1H, H-6), 5.14
(d, J ˆ 3.7, 1H, H-1'), 5.11 (d, J ˆ 6.1, 1H, H-1''), 4.62 (m, 1H, H-2'), 4.31 (m,
1H, H-3''), 4.24 (dd, J ˆ 5.2, 5.2, 1H, H-3'), 4.09 (m, 1H, H-4'), 3.89 ± 3.58
(m, 7H, H-5', H-2'', H-4'', H-5'', H-6''), 3.69 (s, 3H, OMe), 2.13 (s, 3H, Me);
31P NMR (100 MHz, D2O, H-decoupled): d ˆ 2.29, 1.35, 0.18 (3  s,
3 Â P); HRMS-FAB (triethylammonium salt): m/z: calcd for C19H30O19P3:
3-O-(a-d-Glucopyranosyl)uridine 2',3'',4''-trisphosphate (12): A mixture of
5-O-benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)uridine
2',3'',4''-
tris(dibenzylphosphate) (23, 131 mg, 0.90 mmol) and Pd/C (10%, 80 mg)
in methanol (5 mL) was stirred under atmospheric pressure of H2 at room
temperature for 18 h. The catalyst was removed by filtration through Celite
with the resulting filtrate being concentrated in vacuo. The residue was
‡
655.0594 [M‡H] , found: 655.0592.
1-(4-Methylanisol-2-yl)-3-O-(a-d-glucopyranosyl)-a-d-ribofuranose
2',3'',4''-trisphosphate (15a): A mixture of 1-(4-methylanisol-2-yl)-5-O-
benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-a-d-ribofuranose
2',3'',4''-tris(dibenzylphosphate) (32a, 44 mg, 0.30 mmol) and Pd/C (10%,
33 mg) in methanol was stirred under atmospheric pressure of H2 at room
temperature for 75 min. The catalyst was filtered off with Celite and the
resulting filtrate concentrated in vacuo. The residue was dissolved in water
‡
dissolved in water and applied to a Diaion WK-20 resin column (Na form),
which was developed by water. The eluent was evaporated under reduced
pressure and the residues was co-evaporated with ethanol to give 3-O-(a-d-
glucopyranosyl)uridine 2',3'',4''-trisphosphate (12, 62 mg, 98%) as white
1
solids. H NMR (400 MHz, CDCl3): d ˆ 7.65 (d, J ˆ 8.3, 1H, H-6), 5.95 (d,
‡
and applied to a Diaion WK-20 resin column (Na form), which was
J ˆ 4.4, 1H, H-1'), 5.74 (d, J ˆ 8.3, 1H, H-5), 5.15 (brs, 1H, H-1''), 4.74 (m,
1H, H-2'), 4.32 ± 4.28 (m, 2H, H-3', H-3''), 4.17 (m, 1H, H-4''), 3.90 ± 3.50
(m, 7H, H-4', H-5', H-2'', H-5'', H-6''); 31P NMR (100 MHz, D2O,
H-decoupled): d ˆ 1.78, 1.09, 0.23 (3  s, 3  P); HRMS-FAB (triethylam-
monium salts): m/z: calcd for C15H24N2O20P3: 645.0135 [M] , found:
645.0130; UV (water): lmax ˆ 260 nm.
developed with water. The eluent was evaporated under reduced pressure
and the residue was co-evaporated with ethanol to give the sodium salt of
1-(4-methylanisol-2-yl)-3-O-(a-d-glucopyranosyl)-a-d-ribofuranose
2',3'',4''-trisphosphate (15a, 19 mg, 80%). 1H NMR (400 MHz, CDCl3): d ˆ
7.18 (s, 1H, H-3), 7.03 (d, J ˆ 8.3, 1H, H-5), 6.78 (d, J ˆ 8.3, 1H, H-6), 5.31 (s,
1H, H-1'), 5.10 (d, J ˆ 3.4, 1H, H-1''), 4.99 (m, 1H, H-2'), 4.45 (dd, J ˆ 3.9,
8.3, 1H, H-3'), 4.35 (m, 1H, H-3''), 4.17 (m, 1H, H-4'), 4.03 (m, 1H, H-5''),
3.84 (d, J ˆ 10.7, 1H, H-5'a), 3.71 ± 3.60 (m, 5H, H-5'b, H-2'', H-4'', H-6''),
3.66 (s, 3H, OMe), 2.15 (s, 3H, Me); 31P NMR (100 MHz, D2O,
H-decoupled): d ˆ 3.56, 2.65, 0.61 (3  s, 3  P); HRMS-FAB (triethylam-
1-Benzimidazolyl-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose 2',3'',4''-tris-
phosphate (13): A mixture of 1-benzimidazolyl-5-O-benzyl-3-O-(2,6-di-O-
benzyl-a-d-glucopyranosyl)-b-d-ribofuranose 2',3'',4''-tris(dibenzylphos-
phate) (26, 48 mg, 0.033 mmol) and Pd(OH)2 (10%, 120 mg) in a mixture
of cyclohexene (3.0 mL) and methanol (6.0 mL) was heated under reflux
for 90 min. The catalyst was removed by filtration through Celite with the
filtrate being concentrated in vacuo. The residue was dissolved in water and
‡
monium salt): m/z: calcd for C19H30O19P3: 655.0594 [M‡H] , found:
655.0588.
‡
1-(4-Methylnaphthalenyl)-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose
2',3'',4''-trisphosphate (16): A mixture of 1-(4-methylnaphthalenyl)-5-O-
benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-b-d-ribofuranose
2',3'',4''-tris(dibenzylphosphate) (35, 12 mg, 8 mmol) and Pd(OH)2 (10%,
60 mg) in a mixture of cyclohexene (2.0 mL) and methanol (4.0 mL) was
heated under reflux for 90 min. The catalyst was removed by filtration
through Celite with the resulting filtrate being concentrated in vacuo. The
residue was the diluted with water and applied to a Diaion WK-20 resin
applied to a Diaion WK-20 resin column (Na form), which was developed
with water. The eluent was evaporated under reduced pressure and the
residue was co-evaporated with ethanol yielding 1-benzimidazolyl-3-O-(a-
d-glucopyranosyl)-b-d-ribofuranose 2',3'',4''-trisphosphate as the sodium
1
salt (13, 19 mg, 74%). H NMR (400 MHz, CDCl3): d ˆ 8.38 (s, 1H, H-2),
7.69 (d, J ˆ 8.2, 1H, Hbenzimidazole), 7.59 (d, J ˆ 7.3, 1H, Hbenzimidazole), 7.30 ± 7.20
(m, 2H, Hbenzimidazole), 6.21 (d, J ˆ 5.4, 1H, H-1'), 5.17 (d, J ˆ 3.4, 1H, H-1''),
4.96 (m, 1H, H-2'), 4.44 (dd, J ˆ 4.4, 4.8, 1H, H-3'), 4.35 (m, 1H, H-3''), 4.27
(m, 1H, H-4'), 3.90 (m, 1H, H-5''), 3.78 ± 3.58 (m, 6H, H-5', H-2'', H-4'',
H-6''); 31P NMR (100 MHz, D2O, H-decoupled): d ˆ 3.16, 2.76, 0.35 (3  s,
3 Â P); HRMS-FAB (triethylammonium salt): m/z: calcd for
‡
column (Na form), which was developed with water. The eluent was
evaporated under reduced pressure and the residue co-evaporated with
ethanol to yield the sodium salt of 1-(4-methylnaphthalenyl)-3-O-(a-d-
glucopyranosyl)-b-d-ribofuranose 2',3'',4''-trisphosphate (16, 4 mg, 67%).
1H NMR (400 MHz, CDCl3): d ˆ 8.19 (m, 1H, Hnaphthalene), 8.01 (m, 1H,
‡
C18H26O18N2P3: 651.0394 [M‡H] , found: 651.0386.
1-(2-Methoxynaphthalenyl)-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose
2',3'',4''-trisphosphate (14): A mixture of 1-(2-methoxynaphthalenyl)-5-O-
benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-b-d-ribofuranose
2',3'',4''-tris(dibenzylphosphate) (29, 20 mg, 0.013mmol) and Pd(OH)2
(10%, 120 mg) in a mixture of cyclohexene (3.0 mL) and methanol
(6.0 mL) was heated under reflux for 90 min. The catalyst was removed by
filtration through Celite with then resulting filtrate being concentrated in
vacuo. The residue was then diluted with water and applied to a Diaion
H
naphthalene), 7.85 (m, 1H, Hnaphthalene), 7.58 ± 7.49 (m, 2H, 2 Â Hnaphthalene),
7.37 ± 7.26 (m, 1H, Hnaphthalene), 5.73 (d, J ˆ 4.1, 1H, H-1'), 5.14 (d, J ˆ 3.1,
1H, H-1''), 5.04 (m, 1H, H-2'), 4.43 ± 4.28 (m, 2H, H-3', H-3''), 4.16 (m, 1H,
H-4'), 3.87 ± 3.73 (m, 6H, H-5', H-5'', H-6'', OH), 3.67 ± 3.58 (m, 4H, H-2'',
H-4'', 2 Â OH), 2.54 (s, 3H, CH3Ph); 31P NMR (100 MHz, CDCl3,
H-decoupled): d ˆ 2.52, 1.46, 0.72 (3  s, 3  P).
‡
WK-20 resin column (Na form), which was developed with water. The
eluent was evaporated under reduced pressure and the residue co-
evaporated with ethanol to yield the sodium salt of 1-(2-methoxynaph-
Acknowledgement
thalenyl)-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose
2',3'',4''-trisphos-
phate (14, 6 mg, 64%). 1H NMR (400 MHz, CDCl3): d ˆ 8.12 (d, J ˆ 8.3,
1H, Hnaphthalene), 7.85 (d, J ˆ 8.8, 1H, Hnaphthalene), 7.76 (d, J ˆ 7.8, 1H,
We thank the Wellcome Trust for a Programme Grant (060554 to BVLP)
and a Prize Studentship (to R.D.M.) and the Ministry of Education,
Science, Sports and Culture for sabbatical support to S.S. at Bath as a
Senior Visiting Fellow. We also acknowledge useful discussions with
Dr. A. M. Riley.
H
naphthalene), 7.44 (t, J ˆ 7.3, 1H, Hnaphthalene), 7.29 (m, 2H, 2  Hnaphthalene), 5.81
(d, J ˆ 5.4, 1H, H-1'), 5.19 (d, J ˆ 3.4, 1H, H-1''), 5.17 (m, 1H, H-2'), 4.46 ±
4.43 (m, 1H, H-3'), 4.36 ± 4.32 (m, 1H, H-3''), 4.12 (m, 1H, H-4'), 3.90 ± 3.78
(m, 8H, H-5'a, H-5'', H-6'', OCH3, OH), 3.71 ± 3.62 (m, 5H, H-5'b, H-2'',
H-4'', 2  OH); 31P NMR (100 MHz, CDCl3, H-decoupled): d ˆ 2.58, 1.52,
0.27 (3 Â s, 3 Â P).
1-(4-Methylanisol-2-yl)-3-O-(a-d-glucopyranosyl)-b-d-ribofuranose
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A mixture of 1-(4-methylanisol-2-yl)-5-O-
benzyl-3-O-(2,6-di-O-benzyl-a-d-glucopyranosyl)-b-d-ribofuranose
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resulting filtrate concentrated in vacuo. The residue was dissolved in water
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Received: April 23, 2001 [F3218]
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