Synthesis of C-ribosyl 1,2,4-triazolo[3,4-f][1,2,4]triazines as inhibitors of adenosine and AMP deaminases

Article abstract of DOI:10.1039/a905177e

Modified C-nucleosides and nucleotides with an enhanced tendency to undergo covalent hydration are of interest as potential inhibitors of adenosine deaminase (ADA) and AMP deaminase, respectively. In a search for such compounds we have synthesized 6-dimet

Full text of DOI:10.1039/a905177e

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Synthesis of C-ribosyl 1,2,4-triazolo[3,4-f ][1,2,4]triazines as
inhibitors of adenosine and AMP deaminases
Philip J. Dudfield,a Van-Duc Le,b Stephen D. Lindella and Charles W. Reesb
a AgrEvo UK Limited, Chesterford Park, Saffron Walden, Essex, UK CB10 1XL
b Department of Chemistry, Imperial College of Science, Technology and Medicine, London,
UK SW7 2AY
Received (in Cambridge, UK) 28th June 1999, Accepted 24th August 1999
Modified C-nucleosides and nucleotides with an enhanced tendency to undergo covalent hydration are of interest
as potential inhibitors of adenosine deaminase (ADA) and AMP deaminase, respectively. In a search for such
compounds we have synthesized 6-dimethylamino-3-(β--ribofuranosyl)-1,2,4-triazolo[3,4-f ][1,2,4]triazine 4 in
four steps (42% overall yield) from the readily available allonic acid 6 and the hydrazine 7. The hydrazide 16 derived
from 6 and 7 (78%) is converted directly into the cyclised chloro compound 19 (62%) with phosphorus trichloride
oxide, followed by dechlorination (96%) and deprotection (90%). Riboside 4 undergoes partial hydration in water
to the covalent hydrate 22, and is a modest inhibitor of mammalian ADA (IC50 180 µM).
Modified C-nucleosides and nucleotides which are susceptible
to covalent hydration in the aglycone ring system are potential
inhibitors of adenosine deaminase (ADA) and AMP deamin-
ase, respectively. We have recently described the design and
synthesis of the C-nucleoside 6-methylsulfanyl-3-(β--ribo-
furanosyl)imidazo[2,1-f ][1,2,4]triazine 1 as an inhibitor of
adenosine deaminase (IC50 40 µM) which we believe binds to
the enzyme as its covalent hydrate 2.1 The tendency of 1 to
undergo covalent hydration at C-8 was expected to be enhanced
by the introduction of additional nitrogen heteroatoms into the
aglycone. The calculated differences in the heats of form-
ation for such heteroaromatic systems and their corresponding
covalent hydrates support this proposal and indicate that
1,2,4-triazolo[3,4-f ][1,2,4]triazine 3 should readily hydrate.2 In
an effort to produce more strongly inhibiting C-nucleosides we
have now synthesized the C-riboside 4 of the ring system 3,
together with other related 1,2,4-triazolo[3,4-f ][1,2,4]triazines.
Scheme 1
treated with trimethylsilyl cyanide and anhydrous tin() chlor-
ide followed by hydrolysis with conc. hydrochloric acid in acetic
acid to give 6 in 65% overall yield.
3-Dimethylamino-6-hydrazino-1,2,4-triazin-5(4H)-one 7 was
synthesized from 3-dimethylamino-1,2,4-triazine 8 (Scheme 2)
which was made in three steps from thiosemicarbazide by
S-methylation, condensation with glyoxal and treatment of the
resulting 3-(methylthio)triazine with dimethylamine.5 Bromine
in tetrachloromethane converted 8 into the 6-bromo compound
Results and discussion
9,6 but attempted nucleophilic displacement of the bromine
with hydrazine was unsuccessful; the reaction was complex
and a dark intractable tar was formed. 5-Unsubstituted 1,2,4-
triazines are prone to oxidation and to nucleophilic attack at
this position, and so 9 was oxidized with hydrogen peroxide and
acetic acid to give the 5-oxo derivative 10. Nucleophilic dis-
placement of bromine from 10 with hydrazine monohydrate
then proceeded smoothly in boiling water to give the hydrazine
7 in reasonable yield (Scheme 2).
For reasons of synthetic convenience the 6-methylsulfanyl
group of compound 1 was replaced by a 6-dimethylamino
group in our present target nucleoside 4. A convergent route to
the target 4 based upon disconnection of the triazole C3–N4
bond is shown in Scheme 1. 2,5-Anhydro-3,4,6-tri-O-benzoyl-
-allonic acid 6 was available in substantial quantities (>10 g)
as described by Chi and co-workers3 and Kalvoda.4 Com-
mercial 1-O-acetyl-2,3,5-tri-O-benzoyl-β--ribofuranose was
J. Chem. Soc., Perkin Trans. 1, 1999, 2937–2942
This journal is © The Royal Society of Chemistry 1999
2937

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Scheme 2 Reagents, conditions and yields: (i) Br2, CCl4, Et3N, RT, 12 h,
52%; (i.i) H2O2, AcOH, RT, 12 h, 68%; (iii) N2H4ؒH2O, H2O, reflux, 4 h,
63%.
Scheme 4 Reagents, conditions and yields: (i) DCC, N-hydroxy-
succinimide, DCC, DCE, RT, 24 h, 99%; (ii) 7, DMF, 60 ЊC, 24 h, 78%;
(iii) DMF, reflux, 24 h, 58%; (iv) 7, DCC, N-hydroxysuccinimide, DMF,
reflux, 24 h, 65%; (v) NaOMe, MeOH, RT, 12 h, 66%.
and N-hydroxysuccinimide in dry DMF for 24 h (Scheme 4).
The product was cleanly deprotected with sodium methoxide in
methanol at room temperature to give C-nucleoside 18 as a
colourless crystalline solid (66%). The β-configuration of 18
1
was assigned from its H NMR spectrum in DMSO-d6 which
showed the H-1Ј signal as a doublet at δ 4.99, J 5.78 Hz, similar,
for example, to that of the closely related 3-β--ribofuranosyl-
1,2,4-triazolo[3,4-f ][1,2,4]triazin-8(7H)-one.10
It remained to remove the lactam oxo group from the
C-nucleoside 18. Following the synthesis of the aglycone 14, the
tribenzoyl protected C-nucleoside 17 was chlorinated with
phosphorus trichloride oxide and N,N-dimethylaniline (Scheme
5). After 40 min of gentle reflux, chloride 19 was isolated as a
Scheme 3 Reagents, conditions and yields: (i) DMF, AcOH, reflux,
12 h, 55%; (ii) POCl3, PhNMe2, reflux, 40 min, 61%; (iii) H2, Pd/C,
MgO, EtOAc, RT, 4 d, 92%; (iv) N2H4ؒH2O, EtOH, RT, 5 min, 100%;
(v) HgO, EtOH, reflux, 30 min, 54%.
Before proceeding with the synthesis of the C-nucleoside 4
we made the (unknown) aglycone, 6-dimethylamino-1,2,4-
triazolo[3,4-f ][1,2,4]triazine 14 (Scheme 3) as a model com-
pound. The hydrazine 7 was heated under reflux in formic acid
for 6 h, and evaporation and recrystallisation gave the desired
triazolo-triazine 11, but in low yield. A better yield was
obtained with triethyl orthoformate in place of formic acid, but
the best yield was obtained with a refluxing mixture of DMF
in acetic acid which has been used for the cyclisation of
similar hydrazines.7 The oxo group of 11 was readily removed
by conversion into the 8-chloro compound 12 with phosphorus
trichloride oxide and N,N-dimethylaniline followed by hydro-
genolysis with 5% Pd/C and magnesium oxide in ethyl
acetate, or by displacement with hydrazine and oxidation of
13 with yellow mercury() oxide. Though more convenient
and almost quantitative, the hydrogenolysis was much
slower, requiring four days for completion. 6-Dimethylamino-
1,2,4-triazolo[3,4-f ][1,2,4]triazine 14 was obtained as pale
yellow crystals which decomposed at their melting point
(210 ЊC).
Scheme 5 Reagents, conditions and yields: (i) POCl3, PhNMe2, reflux,
40 min, 60%; (ii) POCl3, reflux, 40 min, 62%; (iii) H2, Pd/C, MgO,
EtOAc, RT, 4 days, 96%; (iv) N2H4ؒH2O, EtOAc, RT, 5 min, 88%;
(v) HgO, EtOH, reflux, 1 h, 55%; (vi) MeOH–NH3, RT, 2 days, 86% or
NaOMe, MeOH, RT, 2 h, 90%.
We now turned to the coupling of the hydrazine 7 and the
allonic acid 6; the formation of analogous hydrazides from
this acid has been reported, using DCC alone8 or activated
by HOBT,9 or with 2-ethoxy-N-ethoxycarbonyl-1,2-dihydro-
quinoline (EEDQ).10 We decided to use DCC and N-hydroxy-
succinimide to activate the acid, expecting that the hydroxamic
intermediate might be easier to handle. Exposure of acid 6
to N-hydroxysuccinimide and DCC in 1,2-dichloroethane at
room temperature for 24 h gave the intermediate 15 in near-
quantitative yield. This was isolated and, without purification,
treated with the hydrazine 7 in DMF at 60 ЊC for 24 h to give
hydrazide 16 as pale yellow crystals, which on refluxing in DMF
for a further 24 h gave the protected C-nucleoside 17. This C-
nucleoside was also prepared, in better yield (65%), in a one-pot
reaction by heating a mixture of the hydrazine 7, acid 6, DCC
yellow crystalline solid in 60% yield. A more convenient and
higher yielding method of preparing 19 was to expose the
uncyclised hydrazide 16 to phosphorus trichloride oxide
alone, under gentle reflux, which gave the desired chloride in
62% yield. The chloro compound 19 was dechlorinated by the
two methods described for the aglycone 14: treatment with
hydrazine monhydrate to give 20, which was oxidised with
mercury() oxide to 21 in moderate yield and, in much better
yield, by hydrogenolysis of 19 with 5% palladium on carbon
and magnesium oxide in ethyl acetate for 4 days. All the
compounds in this sequence appeared to be homogeneous
β-epimers by NMR examination. Deprotection of 21, either in
methanol saturated with ammonia gas at room temperature for
2 days or with sodium methoxide in methanol for 2 h, gave the
desired C-nucleoside 4 in excellent yield (Scheme 5).
2938
J. Chem. Soc., Perkin Trans. 1, 1999, 2937–2942

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The 1H NMR spectrum of 4 in DMSO-d6 (containing ≈10%
D2O) confirmed that the configuration at C-1Ј was β, and an
aromatic singlet at δ 9.35, which integrated for one proton,
showed there was no covalent hydration at the C-8 position.
dd, J 5.09, 4.39, H-3), 5.88 (1H, t, J 5.55, H-4), 5.00 (1H, d,
J 4.39, H-2), 4.74–4.75 (1H, m, H-5), 4.62–4.75 (2H, m, H2-6);
δ (76 MHz; CDCl ) [166.17, 165.13, 164.91] (C᎐O), [134.04,
133.87, 133.45, 129.88(×2), 129.82, 129.30, 128.67, 128.60(×2),
128.49, 128.26] (Ar C), 115.86 (CN), 80.96 (C-5), 74.53 (C-4),
71.96 (C-3), 69.52 (C-2), 63.26 (C-6); m/z (FAB, NBA) 472
(MHϩ, 10%), 445 (MHϩ Ϫ CN, 6), 286 (30), 242 (4), 201
(4), 167 (15), 150 (25), 135 (18), 120 (32), 105 (PhCO, 100),
89 (64), 77 (72), 57 (38) (Found: MHϩ, 472.1438. Calc. for
C27H22NO7: MH, 472.1396).
᎐
C
3
1
However, the H NMR spectrum of 4 in D2O alone was more
complex and showed the presence of two components in a ratio
of 55:45. In particular, the C8-H aromatic singlet and the C1Ј-
H doublet which resonated at δ 9.32 and δ 5.42, respectively,
now integrated for only 0.55 protons each and two new signals
were observed at δ 6.33 (d) and δ 5.23 (dd), both integrating for
0.45 protons. These data indicate that in aqueous media com-
pound 4 exists to the extent of 45% as the covalent hydrate 22
2,5-Anhydro-3,4,6-tri-O-benzoyl-D-allonic acid 6
A mixture of 2,5-anhydro-3,4,6-tri-O-benzoyl--allononitrile
(2.91 g, 6.19 mmol), and conc. HCl (3 ml) in acetic acid (12 ml)
was stirred at 100 ЊC for 15 min. The solution was cooled to
25 ЊC and poured into water (40 ml). The aqueous solution was
extracted with ethyl acetate (40 ml) and the organic solution
was washed with brine, dried (MgSO4), and concentrated in
vacuo to give a pale yellow oil, which was purified by flash
chromatography on silica gel (gradient elution; 0–10% MeOH
in DCM) to give the acid 6 (2.72 g, 82%) as a colourless foam;
(1:1 mixture of diastereoisomers at C-8). In contrast, the
formation of a covalent hydrate was not detected in the H
νmax(NaCl/film)/cmϪ1 3445, 3336 (OH), 1729 (C᎐O), 1697
᎐
1
(C᎐O), 1602, 1585, 1493, 1452, 1366, 1316, 1270, 1178, 1123,
᎐
NMR spectrum of compound 1 when run in D2O or DMSO-d6.
This result experimentally supports our starting hypothesis that
the 1,2,4-triazolotriazine ring would be more readily hydrated
than the imidazotriazine. We had hoped to confirm the struc-
ture of 4 by X-ray crystallography and it was, therefore, con-
verted into its tris-p-nitrobenzoate derivative but unfortunately
the crystals proved to be unsuitable for diffraction analysis.
In summary, the synthesis of 6-dimethylamino-1,2,4-tri-
azolo[3,4-f ][1,2,4]triazine C-nucleoside 4 was accomplished
employing a key cyclisation of the hydrazide 16 to the chloro
compound 19 (Scheme 5). The route is convergent and efficient,
requiring only four steps from the readily available 3-dimethyl-
amino-6-hydrazinotriazine 7 and allonic acid 6 and proceeds
in 42% overall yield. Preliminary biochemical studies show that
compound 4 is a modest inhibitor of mammalian ADA (IC50
180 µM). That it is a less potent inhibitor than riboside 1 is,
we believe, attributable to the greater steric requirement of the
NMe2 group over the SMe group. In aqueous solution 4 exists
to the extent of 45% as the hydrate 22 which, to the best of our
knowledge, is the first time that such a covalent hydrate of a
nucleoside has been observed by NMR. Further details of the
biological activity will be reported elsewhere.
1097, 1071, 1026; δH(270 MHz; CDCl3) 7.89–8.10 (6H, m, Ar
H), 7.31–7.62 (9H, m, Ar H), 5.98 (1H, dd, J 5.08, 3.93, H-3),
5.76 (1H, dd, J 6.01, 5.31, H-4), 4.87 (1H, d, J 4.16, H-2), 4.71–
4.77 (3H, m, H-5 and H2-6); δC(76 MHz; CDCl3) 172.92
(CO H), [166.53, 165.29, 165.21] (C᎐O, ester), [133.71, 133.64,
᎐
2
133.35, 129.89, 129.82(×2), 129.45, 128.82, 128.73, 128.56,
128.49(×2)] (Ar C), 80.25 (C-5), 80.03 (C-4), 74.19 (C-3), 72.34
(C-2), 63.94 (C-6); m/z (FAB, NBA) 515 (MHϩ ϩ Na, 4%), 491
(MHϩ, 12), 445 (4), 369 (4), 341 (6), 201 (3), 167 (4), 150 (6), 135
(4), 105 (PhCO, 100), 89 (12), 77 (25), 69 (11), 43 (18) (Found:
MHϩ, 491.1369. Calc. for C27H23O9: MH, 491.1342).
6-Bromo-3-dimethylamino-1,2,4-triazine 9
A solution of bromine (3.20 g, 20 mmol) in tetrachloromethane
(100 ml) was added in one portion to a stirred solution of the
dimethylamine 85 (1.24 g, 10 mmol) in tetrachloromethane (80
ml). Triethylamine (1.69 g, 16.7 mmol) was added to the reac-
tion mixture, which was stirred at 25 ЊC for 12 h. Excess of
solvent was removed in vacuo and the residue was purified by
flash chromatography on silica gel (gradient elution; 10–15%
ether in light petroleum) to furnish the bromo compound 9
(1.06 g, 52%) as a yellow solid, mp 65–66 ЊC (lit.,6 66–67.5 ЊC)
(from DCM–light petroleum); νmax(NaCl/film)/cmϪ1 1578,
1556, 1471, 1412, 1346, 1203, 1076; δH(270 MHz; CDCl3) 8.12
(1H, s, H-5), 3.22 (6H, s, NCH3); δC(76 MHz; CDCl3) 160.34
(C-3), 151.02 (C-5), 134.93 (C-6), 37.15 (NCH3); m/z (EI) 204,
202 (Mϩ, 26%), 174 (5), 149 (15), 147 (15), 95 (5), 80 (6), 70
(100), 55 (5), 42 (16) (Found: Mϩ, 203.9821. Calc. for
C5H781BrN4: M, 203.9834. Found: Mϩ, 201.9838. Calc. for
C5H779BrN4: M, 201.9854).
Experimental
For general points, see ref. 1. NMR assignments are tentative
and coupling constants are in Hz. Ether refers to diethyl ether.
2,5-Anhydro-3,4,6-tri-O-benzoyl-D-allononitrile
To a stirred solution of 1-O-acetyl-2,3,5-tri-O-benzoyl-β--ribo-
furanose (Aldrich) (10.2 g, 20.3 mmol) in 1,2-dichloroethane
(26 ml) was added cyanotrimethylsilane (5.4 ml, 40.5 mmol).
The reaction mixture was treated in one portion via a syringe
with anhydrous stannic [tin()] chloride (2.37 ml, 20.3 mmol).
The darkening solution was stirred for 2 min then poured into
saturated aq. NaHCO3 (200 ml) and stirred for 5 min (pH 7).
DCM (250 ml) was added and the emulsion was filtered
through a Celite pad. The DCM layer was separated, dried
(MgSO4) and evaporated in vacuo to afford light orange syrup,
which was triturated with ethyl acetate–hexane (1:4). The solid
was collected, and washed with hexane to give the title com-
pound (7.54 g, 79%) as a white solid, mp 77–79 ЊC (lit.,11 77–
78 ЊC) (from DCM–light petroleum); νmax(NaCl/film)/cmϪ1
6-Bromo-3-dimethylamino-1,2,4-triazin-5(4H)-one 10
Hydrogen peroxide (27 wt% solution in water; 0.53 ml, 4.56
mmol) was added to a solution of 6-bromo-3-dimethylamino-
1,2,4-triazine 9 (500 mg, 2.46 mmol) in glacial acetic acid (4 ml)
at 5 ЊC. The mixture was stirred at 25 ЊC for 12 h. The precipi-
tate was collected, washed thoroughly with water, air dried, and
crystallised from ethanol to furnish the oxo compound 10 (368
mg, 68%) as white crystals, mp 261–262 ЊC (from ethanol);
νmax(NaCl/Nujol)/cmϪ1 3114, 1608, 1567, 1504, 1435, 1403,
1076, 1016; δH(270 MHz; DMSO-d6) 3.72 (6H, s, NCH3); δC(76
MHz; DMSO-d6) 159.00 (C-5), 154.52 (C-3), 135.10 (C-6),
37.29 (NCH3); m/z (EI) 220, 218 (Mϩ, 20%), 192 (4), 149 (6),
139 (Mϩ Ϫ Br, 7), 129 (3), 113 (50), 105 (2), 71 (44), 44 (100)
(Found: C, 27.6; H, 3.1; N, 25.5. C5H7BrN4O requires C, 27.4;
2253 (CN), 1730 (C᎐O, ester), 1651, 1602, 1585, 1493, 1453,
᎐
1373, 1316, 1268, 1179, 1094, 1071, 1026; δH(270 MHz; CDCl3)
7.92–8.16 (6H, m, Ar H), 7.33–7.89 (9H, m, Ar H), 6.03 (1H,
J. Chem. Soc., Perkin Trans. 1, 1999, 2937–2942
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H, 3.2; N, 25.6%. Found: Mϩ, 220.9866. C5H781BrN4O requires
M, 220.9861. Found: Mϩ, 218.9885. C5H779BrN4O requires M,
218.9881).
H-3), 7.00 (3H, br s, NHNH2), 3.00 (6H, s, NCH3); δC(76 MHz;
DMSO-d6) 158.31 (C-8), 148.55 (C-6), 139.00 (C-3), 133.66
(C-8a), 37.39 (NCH3); m/z (EI) 194 (Mϩ, 100%), 179 (Mϩ Ϫ
CH3, 5), 164 (Mϩ Ϫ 2CH3, 2), 151 (2), 122 (5), 110 (12), 95 (40),
82 (4), 69 (40), 57 (12), 44 (38) (Found: Mϩ, 194.1000. C6H10N8
requires M, 194.1028).
3-Dimethylamino-6-hydrazino-1,2,4-triazin-5(4H)-one 7
Hydrazine monohydrate (1.44 ml, 30 mmol) was added to a
stirred solution of the bromo compound 10 (2.20 g, 10 mmol)
in water (80 ml) at 25 ЊC. The reaction mixture was heated to
reflux for 4 h, allowed to cool to room temperature, and was left
unstirred overnight. The crystalline solid was collected, washed
with water, and air dried to furnish the hydrazine 7 (1.08 g, 63%)
as a white solid, mp 264–266 ЊC (from ethanol); νmax(NaCl/
6-Dimethylamino-1,2,4-triazolo[3,4-f ][1,2,4]triazine 14
Method A. To a solution of the hydrazine 13 (80 mg, 0.41
mmol) in ethanol (4 ml) was added yellow mercury() oxide
(268 mg, 1.24 mmol) at 25 ЊC. The reaction mixture was heated
to reflux for 30 min, cooled and the inorganic residue was
removed (Celite pad), washed with ethanol, and the combined
organic layer evaporated in vacuo to yield a pale yellow solid.
Purification of the solid by flash chromatography on silica gel
(gradient elution; 30–40% ether in light petroleum) followed
by recrystallisation from DCM–light petroleum gave the title
compound 14 (37 mg, 54%) as pale yellow crystals, mp 210–
215 ЊC (decomp.) (from DCM–light petroleum); νmax(NaCl/
Nujol)/cmϪ1 1602, 1556, 1504, 1414; δH(270 MHz; CDCl3) 9.16
(1H, d, J 0.7, H-8), 8.76 (1H, d, J 0.7, H-3), 3.19 (6H, s, NCH3);
δC(76 MHz; CDCl3) 156.97 (C-6), 150.77 (C-8), 138.95 (C-8a),
137.67 (C-3), 37.58 (NCH3); m/z (EI) 164 (Mϩ, 100%), 149
(Mϩ Ϫ CH3, 10), 135 (16), 108 (Mϩ Ϫ CNMe2, 5), 94 (Mϩ Ϫ
NCNMe2, 70), 69 (28), 44 (29), 42 (46) (Found: Mϩ, 164.0803.
C6H8N6 requires M, 164.0810).
Nujol)/cmϪ1 3324, 3301 (NH), 1641 (C᎐O), 1575, 1516, 1397;
᎐
δH(270 MHz; DMSO-d6) 11.25 (2H, br s, NH2), 7.18 (1H, br s,
NH), 2.96 (6H, s, NCH3); δC(76 MHz; DMSO-d6) 158.59 (C-5),
154.22 (C-3), 147.02 (C-6), 37.02 (NCH3); m/z (EI) 170 (Mϩ,
43%), 155 (Mϩ Ϫ CH3, 38), 140 (Mϩ Ϫ 2CH3, 22), 113 (43), 98
(15), 84 (7), 71 (27), 69 (32), 57 (6), 44 (100) (Found: Mϩ,
170.0933. C5H10N6O requires M, 170.0916).
6-Dimethylamino-1,2,4-triazolo[3,4-f ][1,2,4]triazin-8(7H)-
one 11
A mixture of the hydrazine 7 (500 mg, 2.94 mmol), glacial
acetic acid (0.34 ml, 5.88 mmol) and DMF (50 ml) was refluxed
for 12 h. After cooling to room temperature, crystals were
induced to form by addition of ether. These were collected, and
recrystallised from water to yield the title compound 11 (291 mg,
55%) as white crystals, mp >300 ЊC (decomp.) (from water);
Method B. To a solution of chloro compound 12 (50 mg, 0.25
mmol) in dry ethyl acetate (4 ml) were added 5% palladium
on carbon (28 mg) and magnesium oxide (26 mg, 0.66 mmol).
The mixture was stirred at room temperature under a hydrogen
balloon for 4 days. The inorganic material was removed by
filtration through a short pad of Celite and was washed
thoroughly with ethyl acetate. The filtrate was concentrated
in vacuo and the residue was purified by flash chromatography
on silica gel (gradient elution; 30–40% ether in light petroleum)
to afford the title compound 14 (38 mg, 92%), identical to that
described above.
νmax(NaCl/Nujol)/cmϪ1 3151 (NH), 1719 (C᎐O), 1608, 1556,
᎐
1364, 1290; δH(270 MHz; DMSO-d6) 9.06 (1H, s, H-3), 2.99
(6H, s, NCH3); δC(76 MHz; DMSO-d6) 153.71 (C-8), 152.77
(C-6), 139.82 (C-3), 139.42 (C-8a), 38.46 (NCH3); m/z (EI) 180
(Mϩ, 35%), 138 (5), 110 (6), 96 (26), 82 (21), 71 (92), 57 (45), 43
(100) (Found: Mϩ, 180.0766. C6H8N6O requires M, 180.0760).
8-Chloro-6-dimethylamino-1,2,4-triazolo[3,4-f ][1,2,4]triazine
12
A mixture of 11 (150 mg, 0.83 mmol), N,N-dimethylaniline
(1 ml) and phosphorus trichloride oxide (4 ml) was heated
to reflux for 40 min. After cooling to room temperature, excess
of solvent was removed in vacuo and ice–water (2 ml) was added
to the residue. The aqueous solution was extracted with ethyl
acetate (3 × 2 ml), and the extract was dried (MgSO4), and
concentrated in vacuo to give a dark residue, which was purified
by flash chromatography on silica gel (gradient elution; 10–25%
ether in light petroleum) to afford the title compound 12
(101 mg, 61%) as yellow crystals, mp 188–190 ЊC (from DCM–
light petroleum); νmax(NaCl/Nujol)/cmϪ1 1694, 1651, 1592,
1491, 1455, 1417, 1382; δH(270 MHz; CDCl3) 8.81 (1H, s, H-3),
3.18 (6H, s, NCH3); δC(76 MHz; CDCl3) 155.94 (C-8), 152.36
(C-6), 138.93 (C-3), 138.67 (C-8a), 37.70 (NCH3); m/z (EI)
200 (Mϩ, 32%), 198 (Mϩ, 100), 183 (Mϩ Ϫ CH3, 8), 168
(Mϩ Ϫ 2CH3, 8), 156 (8), 130 (25), 128 (62), 108 (8), 82 (28), 44
(45) (Found: C, 36.5; H, 3.5; N, 42.1. C6H7ClN6 requires C,
36.3; H, 3.55; N, 42.3%. Found: Mϩ, 200.0398. C6H737ClN6
requires M, 200.0391. Found: Mϩ, 198.0429. C6H735ClN6
requires M, 198.0421).
N-(2,5-Anhydro-3,4,6-tri-O-benzoyl-D-allonoyl)-NЈ-(3-dimethyl-
amino-4,5-dihydro-5-oxo-1,2,4-triazin-6-yl)hydrazine 16
To a solution of the acid 6 (1.85 g, 3.18 mmol) in dry 1,2-
dichloroethane (32 ml) were added DCC (857 mg, 4.15 mmol)
and N-hydroxysuccinimide (478 mg, 4.15 mmol). The reaction
mixture was stirred at room temperature under N2 for 24 h.
The precipitate of dicyclohexyurea was filtered off and the fil-
trate was removed in vacuo to give the crude product 15 (99%)
as a colourless foam, which was used without purification in the
next step.
To a stirred solution of the hydrazine 7 (706 mg, 4.15 mmol)
in dry DMF (120 ml) was added a solution of the activated acid
15 (2.20 g, 3.78 mmol) in dry DMF (20 ml) at room temper-
ature. The reaction mixture was stirred at 60 ЊC under N2 for 24
h. Excess of solvent was removed in vacuo and the residue was
dissolved in DCM. The organic solution was washed succes-
sively with water and brine, dried (MgSO4), and evaporated in
vacuo to give the crude product as a yellow foam. Purification
of this by flash chromatography on silica gel (gradient elution;
5–15% acetone in DCM) afforded the hydrazide 16 (1.88 g, 78%)
as pale yellow crystals, mp 126–128 ЊC; νmax(NaCl/film)/cmϪ1
6-Dimethylamino-8-hydrazino-1,2,4-triazolo[3,4-f ][1,2,4]-
triazine 13
3253 (NH), 1730 (C᎐O, ester), 1715 (C᎐O, amide), 1651, 1644,
᎐
᎐
To a solution of chloro compound 12 (100 mg, 0.50 mmol) in
ethanol (4 ml) was added hydrazine monohydrate (0.03 ml, 0.55
mmol) at 25 ЊC during 5 min. The precipitate which formed
was collected, and washed with ethyl acetate. The crude product
was recrystallised from ethanol to give the title compound 13
(108 mg, 100%) as colourless crystals, mp 255–260 ЊC (decomp.)
(from ethanol); νmax(NaCl/Nujol)/cmϪ1 3319, 3255, 3151 (NH),
1565, 1549, 1416, 1354; δH(300 MHz; DMSO-d6) 9.05 (1H, s,
1634, 1602, 1587, 1515, 1505, 1454, 1271; δH(270 MHz; CDCl3)
(locants for carbohydrate moiety primed) 9.98 (1H, br s, NH),
8.96 (1H, d, J 3.46, NH), 7.83–7.96 (4H, m, Ar H), 7.80 (2H, d,
J 1.38, Ar H), 7.28–7.58 (9H, m, Ar H), 6.16 (1H, dd, J 8.21,
4.62, H-2Ј), 6.00 (1H, dd, J 4.85, 2.08, H-3Ј), 4.94 (1H, d, J 2.08,
H-1Ј), 4.81–4.86 (1H, m, H-4Ј), 4.67 (1H, s, NH), 4.62–4.71
(2H, m, H2-5Ј), 3.04 (6H, s, NCH3); δC(76 MHz; CDCl3)
(locants for carbohydrate moiety primed) 169.44 (C᎐O,
᎐
2940
J. Chem. Soc., Perkin Trans. 1, 1999, 2937–2942

View Article Online
hydrazide), [166.52, 165.56, 165.26] (C᎐O, ester), 158.68 (C-5),
22%), 313 (MHϩ, 85), 286 (15), 223 (16), 176 (38), 165 (20),
᎐
153.78 (C-3), 143.42 (C-6), [133.63, 133.56, 133.39, 129.78,
129.72, 129.55, 129.25, 129.02, 128.70, 128.49, 128.42, 128.29]
(Ar C), 81.27 (C-4Ј), 79.22 (C-3Ј), 75.15 (C-2Ј), 71.52 (C-1Ј),
63.40 (C-5Ј), 36.76 (NCH3); m/z (FAB, NBA) 643 (MHϩ,
100%), 306 (6), 290 (10), 196 (10), 167 (11), 150 (20), 135 (18),
120 (24), 105 (74), 89 (40), 77 (46), 55 (22), 39 (39) (Found: C,
59.65; H, 4.4; N, 13.3. C32H30N6O9 requires C, 59.8; H, 4.7;
N, 13.1%. Found: MHϩ, 643.2222. C32H31N6O9 requires MH,
643.2153).
152 (34), 133 (25), 120 (45), 90 (65), 77 (100), 63 (42), 51 (46)
(Found: MHϩ, 313.1275. C11H17N6O5 requires MH, 313.1260).
8-Chloro-6-dimethylamino-3-(2Ј,3Ј,5Ј-tri-O-benzoyl-ꢀ-D-ribo-
furanosyl)-1,2,4-triazolo[3,4-f ][1,2,4]triazine 19
Method A. A mixture of the protected C-nucleoside 17 (150
mg, 0.24 mmol), N,N-dimethylaniline (1 ml) and phosphorus
trichloride oxide (4 ml) was heated to reflux for 40 min. After
cooling of the mixture to room temperature, excess of solvent
was removed in vacuo and ice–water (4 ml) was added to the
residue. The aqueous solution was extracted with ethyl acetate
(3 × 6 ml), and the combined organic layer was dried (MgSO4),
and concentrated in vacuo to give a dark residue, which was
purified by flash chromatography on silica gel (gradient elution;
30–40% ether in light petroleum) to afford the chloro compound
19 (93 mg, 60%) as yellow crystals, mp 88–90 ЊC (from DCM–
6-Dimethylamino-3-(2Ј,3Ј,5Ј-tri-O-benzoyl-ꢀ-D-ribofuranosyl)-
1,2,4-triazolo[3,4-f ][1,2,4]triazin-8(7H)-one 17
Method A. A solution of the hydrazide 16 (200 mg, 0.31
mmol) in dry DMF (40 ml) was heated to reflux under N2 for
24 h. After the solution had cooled to room temperature, excess
of solvent was removed in vacuo and the residue was dissolved
in DCM. The organic solvent was washed successively with
water and brine, dried (MgSO4), and evaporated in vacuo to give
the crude product as a yellow solid. Purification of the residue
by flash chromatography on silica gel (gradient elution; 2–5%
acetone in DCM) afford the title compound 17 (113 mg, 58%)
as a white solid, mp 125–126 ЊC (from light petroleum–EtOAc);
light petroleum); νmax(NaCl/film)/cmϪ1 1729 (C᎐O), 1596, 1574,
᎐
1505, 1486, 1452, 1417, 1316, 1270, 1123, 1096; δH(270 MHz;
CDCl3) 7.91–8.00 (6H, m, Ar H), 7.49–7.56 (3H, m, Ar H),
7.31–7.38 (6H, m, Ar H), 6.48 (1H, dd, J 5.67, 4.39, H-2Ј), 6.18
(1H, t, J 6.24, H-3Ј), 5.88 (1H, d, J 4.39, H-1Ј), 4.63–4.82 (3H,
m, H-4Ј and H2-5Ј), 3.21 (6H, s, NCH3); δC(76 MHz; CDCl3)
νmax(NaCl/film)/cmϪ1 3200 (NH), 1728 (C᎐O, ester), 1611, 1493,
[166.19, 165.21(×2)] (C᎐O), [155.87, 152.64, 146.41, 139.16]
᎐
᎐
1452, 1381, 1316, 1270, 1123; δH(270 MHz; CDCl3) 7.92–
8.11 (6H, m, Ar H), 7.31–7.57 (9H, m, Ar H), 6.44 (1H, dd,
J 5.78, 4.39, H-2Ј), 6.12 (1H, t, J 6.24, H-3Ј), 5.82 (1H, d,
J 4.39, H-1Ј), 4.64–4.80 (3H, m, H-4Ј and H2-5Ј), 3.19 (6H,
(Het C), [133.53, 133.48, 133.13, 129.76(×2), 129.70, 129.46,
128.88, 128.47, 128.41(×2), 128.32] (Ar C), 79.57 (C-4Ј),
75.38 (C-3Ј), 72.70 (C-2Ј), 72.51 (C-1Ј), 63.78 (C-5Ј), 37.93
(NCH3); m/z (FAB, NBA) 643 (MHϩ, 20%), 434 (Mϩ Ϫ
2PhCO, 5), 393 (6), 336 (4), 322 (22), 282 (4), 250 (6), 165 (11),
133 (21), 105 (100), 91 (28), 81 (34), 69 (46), 55 (70) (Found:
C, 59.5; H, 3.95; N, 12.9. C32H27ClN6O7 requires C, 59.8; H, 4.2;
N, 13.1%. Found: MHϩ, 643.1738. C32H28ClN6O7 requires MH,
643.1708).
s, NCH ); δ (76 MHz; CDCl ) [171.11, 166.29, 165.29] (C᎐O,
᎐
3
C
3
ester), 153.32 (C-8), 149.93 (C-6), 147.09 (C-8a), 139.49
(C-3), [133.57(×2), 133.21, 130.14, 129.81(×2), 129.52, 128.92,
128.46(×2), 128.40(×2)] (Ar C), 79.59 (C-4Ј), 75.29 (C-3Ј),
73.12 (C-2Ј), 72.52 (C-1Ј), 63.92 (C-5Ј), 38.60 (NCH3);
m/z (FAB, NBA) 625 (MHϩ, 100%), 503 (4), 259 (4), 209 (2),
178 (2), 165 (4), 135 (8), 123 (12), 105 (72), 81 (26), 69 (46), 55
(50) (Found: C, 60.7; H, 4.1; N, 13.1. C32H28N6O8 requires C,
61.5; H, 4.5; N, 13.5%. Found: MHϩ, 625.2090. C32H29N6O8
requires MH, 625.2047).
Method B. A mixture of the hydrazide 16 (100 mg, 0.16
mmol) and phosphorus trichloride oxide (4 ml) was heated to
reflux for 40 min. After cooling the mixture to room temper-
ature, excess of solvent was removed in vacuo and ice–water
(4 ml) was added to the residue. The aqueous solution was
extracted with ethyl acetate (3 × 4 ml), dried (MgSO4), and con-
centrated in vacuo to give a dark residue, which was purified by
flash chromatography on silica gel (gradient elution; 30–40%
ether in light petroleum) to afford the chloro compound 19 (78
mg, 62%), identical to that described above.
Method B. A mixture of the hydrazine 7 (100 mg, 0.59
mmol), the acid 6 (318 mg, 0.65 mmol), DCC (134 mg, 0.65
mmol), and N-hydroxysuccinimide (74.5 mg, 0.65 mmol) in dry
DMF (40 ml) was heated to reflux for 24 h. After allowing the
mixture to cool to room temperature, excess of solvent was
removed in vacuo and the residue was dissolved in EtOAc. The
organic solvent was washed successively with water and brine,
dried (MgSO4), and evaporated in vacuo to give the crude
product as a yellow solid. Purification of the residue by flash
chromatography on silica gel (gradient elution; 2–5% acetone in
DCM) gave the title compound 17 (63 mg, 65%), identical to
that described above.
6-Dimethylamino-8-hydrazino-3-(2Ј,3Ј,5Ј-tri-O-benzoyl-ꢀ-D-
ribofuranosyl)-1,2,4-triazolo[3,4-f ][1,2,4]triazine 20
To a solution of the chloro compound 19 (80 mg, 0.13 mmol) in
ethyl acetate (2 ml) was added hydrazine monohydrate (0.007
ml, 0.14 mmol) at 25 ЊC during 5 min. A yellow precipitate was
collected, and washed with ethyl acetate. The crude product
was crystallised from ethyl acetate–light petroleum to give the
hydrazine 20 (70 mg, 88%) as pale yellow crystals, mp 78–79 ЊC
(from ethyl acetate–light petroleum); νmax(NaCl/film)/cmϪ1
6-Dimethylamino-3-(ꢀ-D-ribofuranosyl)-1,2,4-triazolo[3,4-f ]-
[1,2,4]triazin-8(7H)-one 18
To a stirred solution of the protected C-nucleoside 17 (100
mg, 0.16 mmol) in dry methanol (2 ml) was added sodium
methoxide (52 mg, 0.96 mmol). The reaction mixture was
stirred at room temperature for 12 h and was quenched with
water (0.2 ml). The solution was evaporated to dryness and the
residue was crystallised from ethanol to afford the title com-
pound 18 (35 mg, 66%) as a white solid, mp 228–230 ЊC (from
3320, 3217 (NH), 1725 (C᎐O), 1602, 1584, 1548, 1537, 1452,
᎐
1316, 1270, 1124, 1098; δH(270 MHz; CDCl3) 7.92–8.00 (6H, m,
Ar H), 7.80 (1H, d, J 1.62, NH), 7.31–7.57 (9H, m, Ar H), 6.51
(1H, dd, J 5.66, 3.93, H-2Ј), 6.27 (1H, dd, J 6.93, 5.77, H-3Ј),
5.85 (1H, d, J 3.93, H-1Ј), 4.71–4.80 (2H, m, H-4Ј and H-5aЈ),
4.64–4.68 (1H, m, H-5bЈ), 3.18 (6H, s, NCH3); δC(68 MHz;
CDCl ) [166.21, 165.24, 165.18] (C᎐O), [158.08, 154.80, 149.77,
᎐
3
ethanol); νmax(NaCl/Nujol)/cmϪ1 3200 (OH, NH), 1723 (C᎐O,
145.65] (Het C), [133.39, 133.35, 133.00, 131.86, 129.75, 129.56,
129.07, 129.01, 128.68, 128.37, 128.34, 128.24] (Ar C), 79.24
(C-4Ј), 75.58 (C-3Ј), 72.97 (C-2Ј), 72.57 (C-1Ј), 63.98 (C-5Ј),
37.62 (NCH3); m/z (FAB, NBA) 639 (MHϩ, 100), 461 (3), 433
(3), 391 (3), 371 (5), 309 (6), 290 (13), 273 (9), 221 (6), 166 (13),
152 (20), 135 (18), 120 (27), 105 (77), 89 (42), 77 (51), 69 (24),
55 (31) (Found: MHϩ, 639.2366. C32H31N8O7 requires MH,
639.2316).
᎐
amide), 1608; δH(400 MHz; DMSO-d6 ϩ D2O) 4.99 (1H, d,
J 5.78, H-1Ј), 4.60 (1H, t, J 5.50, H-2Ј), 4.08 (1H, t, J 5.08,
H-3Ј), 3.81 (1H, q, J 4.94, H-4Ј), 3.53–3.56 (1H, m, H-5aЈ),
3.39–3.43 (1H, m, H-5bЈ), 2.94 (6H, s, NCH3); δC(76 MHz;
DMSO-d6) 159.30 (C-8), 159.07 (C-6), 147.18 (C-3), 141.43
(C-8a), 85.45 (C-4Ј), 76.04 (C-1Ј), 72.87 (C-2Ј), 72.15 (C-3Ј),
62.94 (C-5Ј), 38.09 (NCH3); m/z (FAB, NBA) 335 (MHϩ ϩ Na,
J. Chem. Soc., Perkin Trans. 1, 1999, 2937–2942
2941

View Article Online
6-Dimethylamino-3-(2Ј,3Ј,5Ј-tri-O-benzoyl-ꢀ-D-ribofuranosyl)-
1,2,4-triazolo[3,4-f ][1,2,4]triazine 21
Method B. To a stirred solution of the protected C-nucleoside
21 (50 mg, 0.08 mmol) in dry MeOH (4 ml) was added sodium
methoxide (14 mg, 0.26 mmol). The reaction mixture was
stirred at room temperature for 2 h and was quenched with
water (0.1 ml). Excess of solvent was removed in vacuo and the
residue was purified by flash chromatography on silica gel
(gradient elution; 10–15% MeOH in DCM) to give the C-nucleo-
side 4 (21.9 mg, 90%), which was identical to that described
above.
Method A. To a solution of the hydrazine 20 (60 mg, 0.09
mmol) in ethanol (4 ml) was added yellow mercury() oxide (61
mg, 0.28 mmol) at 25 ЊC. The reaction mixture was heated to
reflux for 1 h, cooled, and the inorganic residue was removed
(Celite pad), washed with ethanol, and the combined organic
layer evaporated in vacuo to yield a pale yellow solid. Purifi-
cation of the solid by flash chromatography on silica gel (gradi-
ent elution; 10–20% ether in light petroleum) afforded the title
compound 21 (31 mg, 55%) as pale yellow crystals, mp 79–
80 ЊC (from DCM–light petroleum); νmax(NaCl/film)/cmϪ1
6-Dimethylamino-3-(2Ј,3Ј,5Ј-tri-O-p-nitrobenzoyl-ꢀ-D-ribo-
furanosyl)-1,2,4-triazolo[3,4-f ][1,2,4]triazine
1726 (C᎐O), 1601, 1565, 1122, 1097, 1071, 1026; δ (270 MHz;
To a stirred solution of the C-nucleoside 4 (10 mg, 0.03 mmol)
in dry pyridine (2 ml) was added p-nitrobenzoyl chloride (37.6
mg, 0.20 mmol). The reaction mixture was stirred at room tem-
perature for 2 h and excess of solvent was removed in vacuo to
give a dark residue. The residue was dissolved in DCM, washed
with brine, dried (MgSO4), and concentrated in vacuo to give a
crude product, which was purified by flash chromatography on
silica gel (gradient elution; 0–5% ethyl acetate in ether) to
furnish the tris-p-nitrobenzoate (23.3 mg, 93%) as yellow
crystals, mp 114–115 ЊC (from DCM–hexane); νmax(NaCl/film)/
᎐
H
CDCl3) 9.19 (1H, s, H-8), 7.93–8.02 (6H, m, Ar H), 7.50–7.56
(3H, m, Ar H), 7.34–7.40 (6H, m, Ar H), 6.48 (1H, dd, J 5.78,
4.39, H-2Ј), 6.21 (1H, t, J 6.24, H-3Ј), 5.90 (1H, d, J 4.16, H-1Ј),
4.66–4.80 (3H, m, H-4Ј and H2-5Ј), 3.24 (6H, s, NCH3); δC(76
MHz; CDCl ) [166.20, 165.18(×2)] (C᎐O), [156.84, 151.06
᎐
3
(C-8), 145.00, 140.09] (Het C), [133.48, 133.42, 133.08, 129.93,
129.76(×2), 129.52, 128.93, 128.40(×2), 128.30(×2)] (Ar C),
79.44 (C-4Ј), 75.24 (C-3Ј), 72.84 (C-2Ј), 72.52 (C-1Ј), 63.93
(C-5Ј), 37.82 (NCH3); m/z (FAB, NBA) 609 (MHϩ, 100%), 487
(Mϩ Ϫ PhCO2, 5), 311 (4), 286 (6), 259 (4), 243 (6), 193 (4), 167
(8), 150 (12), 133 (16), 120 (12), 105 (84), 89 (22), 77 (34), 43 (22)
(Found: C, 63.3; H, 4.6; N, 13.5. C32H28N6O7 requires C, 63.15;
H, 4.6; N, 13.8%. Found: MHϩ, 609.2113. C32H29N6O7 requires
MH, 609.2098).
cmϪ1 1734 (C᎐O), 1602, 1528, 1349, 1270; δ (270 MHz; CDCl )
᎐
H
3
9.21 (1H, s, H-8), 8.09–8.31 (12H, m, Ar H), 6.53 (1H, t, J 5.09,
H-2Ј), 6.31 (1H, t, J 5.54, H-3Ј), 5.95 (1H, d, J 4.16, H-1Ј), 4.63–
4.88 (3H, m, H-4Ј and H2-5Ј), 3.26 (6H, s, NCH3); δC(68 MHz;
CDCl ) [164.44, 163.42(×2)] (C᎐O), [157.04, 151.21, 151.00,
᎐
3
150.76] (Het C), [144.71, 140.14, 134.71, 133.91, 131.04,
130.86(×2), 130.83, 123.84, 123.79(×2), 123.62] (Ar C), 79.45
(C-4Ј), 74.12 (C-3Ј), 73.99 (C-2Ј), 73.11 (C-1Ј), 64.25 (C-5Ј),
37.84 (NCH3); m/z (FAB, NBA) 744 (MHϩ, 8%), 669 (5),
515 (10), 485 (4), 461 (8), 369 (2), 273 (2), 135 (12), 109 (24), 91
(34), 69 (62), 55 (100) (Found: MHϩ, 744.1684. C32H26N9O13
requires MH, 744.1650).
Method B. To a solution of the chloro compound 19 (100 mg,
0.16 mmol) in dry ethyl acetate (6 ml) were added 5% palladium
on carbon (17 mg) and magnesium oxide (16 mg, 0.41 mmol).
The reaction mixture was stirred at room temperature under a
hydrogen atmosphere via a balloon for 4 days. The inorganic
material was removed by filtration through a pad of Celite and
was washed thoroughly with ethyl acetate. The filtrate was con-
centrated in vacuo and the residue was purified by flash chrom-
atography on silica gel (gradient elution; 10–20% ether in light
petroleum) to afford the title compound 21 (91.5 mg, 96%),
identical to that described above.
Acknowledgements
We thank AgrEvo UK Limited for a research studentship (to
V.-D. Le), Ms T. Monk for performing the ADA assay, and the
Wolfson Foundation for establishing the Wolfson Centre for
Organic Chemistry in Medical Science at Imperial College.
6-Dimethylamino-3-(ꢀ-D-ribofuranosyl)-1,2,4-triazolo[3,4-f ]-
[1,2,4]triazine 4
References
Method A. A solution of the protected C-nucleoside 21 (90
mg, 0.15 mmol) in MeOH–NH3 (5 ml, saturated at 0 ЊC) was
stirred at room temperature for 2 days. Excess of solvent was
removed in vacuo and the residue was purified by flash chrom-
atography on silica gel (gradient elution; 10–15% MeOH in
DCM) to give the title compound 4 (38 mg, 86%) as pale yellow
crystals; mp 171–173 ЊC (from acetone); νmax(NaCl/film)/cmϪ1
3387, 3230 (OH), 1614, 1573, 1481, 1440, 1423, 1344, 1285,
1216, 1130, 1100, 1055, 1032; δH(270 MHz, DMSO-d6 ϩ D2O)
9.35 (1H, s, H-8), 5.16 (1H, d, J 6.24, H-1Ј), 4.68 (1H, t, J 5.32,
H-2Ј), 4.15 (1H, t, J 5.08, H-3Ј), 3.88–3.93 (1H, m, H-4Ј), 3.44–
3.62 (2H, m, H2-5Ј), 3.12 (6H, s, NCH3); δH(270 MHz; D2O)
9.32 (0.55H, s, H-8), 6.33 (0.45H, d, “J” 2.8, H-8), 5.42 (0.55H,
d, J 6.2, H-1Ј), 5.23 (0.45H, dd, “J” 6.2 and 2.8, H-1Ј), 4.92
(0.55H, t, J 6.0, H-2Ј), 4.71 (0.45H, t, J 6.0, H-2Ј), 4.43 (0.55H,
t, J 5.8, H-3Ј), 4.34 (0.45H, dt, “J” 5.8 and 9.4, H-3Ј), 4.17 (1H,
m, H-4Ј), 3.68–3.92 (2H, m, H2-5Ј), 3.23 (3.3H, s, NCH3), 3.04
(2.7H, s, NCH3); δC(76 MHz; DMSO-d6) 156.90 (C-6), 152.52
(C-8), 147.11 (C-8a), 140.08 (C-3), 85.64 (C-4Ј), 74.87 (C-1Ј),
72.63 (C-2Ј), 71.91 (C-3Ј), 62.49 (C-5Ј), 37.74 (NCH3); m/z
(FAB, NBA) 319 (M ϩ Naϩ, 100%), 297 (MHϩ, 53), 205 (31),
178 (9), 149 (24), 133 (21), 95 (34), 81 (59), 69 (100), 55 (95)
(Found: C, 44.1; H, 5.25; N, 28.2. C11H16N6O4 requires C, 44.6;
H, 5.4; N, 28.4%. Found: MHϩ, 297.1330. C11H17N6O4 requires
MH, 297.1311).
1 P. J. Dudfield, V.-D. Le, S. D. Lindell and C. W. Rees, J. Chem. Soc.,
Perkin Trans. 1, 1999, 2929.
2 C. G. Earnshaw, AgrEvo UK Ltd, unpublished results. Further
details of our calculations can be found in V.-D. Le, Ph.D. Thesis,
University of London, 1997, p. 26 and in S. D. Lindell,
B. A. Moloney, B. D. Hewitt, C. G. Earnshaw, P. J. Dudfield and
J. E. Dancer, Bioorg. Med. Chem. Lett., 1999, 9, 1985. See also
M. D. Erion and M. R. Reddy, J. Am. Chem. Soc., 1998, 120, 3295.
3 H. K. Han, J. C. Lee, Y. H. Kang, J.-H. Kim and D. Y. Chi, Synth.
Commun., 1992, 22, 2815.
4 L. Kalvoda, J. Carbohydr. Nucleosides, Nucleotides, 1976, 3, 47.
5 W. W. Paudler and T.-K. Chen, J. Heterocycl. Chem., 1970, 7, 767;
H. Neunhoeffer and B. Lehmann, Chem. Ber., 1976, 109, 1113.
6 B. T. Keen, R. J. Radel and W. W. Paudler, J. Org. Chem., 1977, 42,
3498; R. J. Radel, J. L. Atwood and W. W. Paudler, J. Org. Chem.,
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