The synthesis of a tricyclic pyrrolopyrimidine related to N6-hydroxyadenine

Article abstract of DOI:10.1039/a606472h

The synthesis of 9-methylpyrrolo[4,3,2-de]pyrimido[4,5-c]dihydrooxazepine 34, a tricyclic pyrrolo[2,3-d]pyrimidine analogue of the mutagenic purine N⁶-hydroxyadenine, and several novel pyrrolo[2,3-d]pyrimidines is described. The presence of the

Full text of DOI:10.1039/a606472h

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The synthesis of a tricyclic pyrrolopyrimidine related to
N 6-hydroxyadenine
David M. Williams,*,a Dmitry Yu. Yakovlevb and Daniel M. Brownc
a
Present address, Krebs Institute, Department of Chemistry, University of Sheffield,
Brook Hill, Sheffield S3 7HF, UK
b Present address, Engelhardt Institute of Molecular Biology, Russian Academy of Sciences,
Vavilov Str. 32, 1179847 Moscow, Russia
c Medical Research Council, Laboratory of Molecular Biology, Hills Road,
Cambridge CB2 2QH, UK
The synthesis of 9-methylpyrrolo[4,3,2-de]pyrimido[4,5-c]dihydrooxazepine 34, a tricyclic pyrrolo[2,3-
d]pyrimidine analogue of the mutagenic purine N6-hydroxyadenine, and several novel pyrrolo[2,3-
d]pyrimidines is described. The presence of the third ring constrains the amino substituent of 34 to an anti
orientation and is expected to improve dramatically the base-pairing characteristics of the analogue with
both cytosine and thymine when present in D NA. An intramolecular cyclisation reaction of 5-
(aminooxyethyl)-4-chloro-7-methyl-2-methylsulfonyl-7H -pyrrolo[2,3-d]pyrimidine 30 gave 33, which was
converted into the target molecule 34 via the displacement of the methylsulfonyl group with hydrazine
followed by oxidation of the hydrazino group with mercuric oxide. An analogous cyclisation with 5-
(aminooxyethyl)-4-chloro-7-methyl-7H -pyrrolo[2,3-d]pyrimidine 31 was less effective, whilst the
corresponding 2-amino derivative 32 failed to cyclise.
We have been interested in the synthesis of nucleoside ana-
Results and discussion
In the earlier experiments6 we introduced the carbon substitu-
logues with ambivalent base-pairing properties.1–3 The 2Ј-deoxy-
ribosides of such analogues as 11 (a bicyclic N4-methoxy-
cytosine analogue), N6-methoxyadenine and N6-methoxy-2,6-
diaminopurine have been shown to be extremely useful in mixed
sequence oligonucleotide primers used in PCR and DNA
sequencing.2 In addition, we have recently exploited the base-
pairing characteristics1,4 of the 5Ј-triphosphate of 1 in a PCR-
based random mutagenesis procedure.5 It was clear to us that
conformationally restrained analogues such as 1 are more
effective than N4-methoxycytosine for such applications as
exemplified by the thermal stabilities of oligonucleotide
duplexes containing 1.1 In the same way we envisaged the tri-
ent at C-5 of the pyrrolo[2,3-d]pyrimidine ring using a
Mannich-type reaction. In order to introduce the two-carbon
substituent at C-5 in 3 it was decided to generate an hydroxy-
ethyl residue during the pyrrole ring-closure, thus involving
an acid-catalysed, intramolecular cyclisation of a suitable 5-
(acetal)-6-amino pyrimidine, based on earlier chemistry.8 The
resulting hydroxyethyl derivative would then be converted into
an aminooxyethyl residue to allow nucleophilic displacement of
a suitable substituent at C-4 of the pyrrolo[2,3-d]pyrimidine
ring. To this end, dihydrofuran was converted into 2-methoxy-
3-bromotetrahydrofuran 4 by bromination at Ϫ78 ЊC in
methanol9 or, more conveniently and in higher yield, via the
2,3-dibromo adduct,10 followed without purification, by meth-
anolysis. In the former procedure a trans:cis ratio of 85:15 was
obtained,11 whilst a 32:68 mixture was obtained via the trans-
dibromide. When 3 was heated in DMF at 140 ЊC for 20 h with
the sodium salt of ethyl cyanoacetate (generated using sodium
hydride) the derivative 5 was obtained in 15% yield as a mixture
of diastereoisomers (Scheme 1). Although a wide variety of
conditions were investigated, higher yields were not obtained.
This was so regardless of the diastereoisomeric ratio of the
starting material 4. No product was obtained using weaker
bases such as sodium ethoxide in the reaction.
We envisaged that the ring system 3 (R = NH2) would be
obtained either by cyclisation of a suitable 2-amino-7H-
pyrrolo[2,3-d]pyrimidine precursor or by displacement of a
2-methylsulfonyl group subsequent to cyclisation. It was
expected that the latter compound would be available from the
corresponding 2-sulfanyl-7H-pyrrolo[2,3-d]pyrimidine, which
would also furnish a route to 3 (R = H). Thus, reaction of the
cyano ester 5 with thiourea or guanidine in ethanol afforded the
pyrimidines 6 and 7, respectively. The presence of two dia-
stereoisomers in each case was evidenced by both TLC and by
the presence of two sets of signals for the 6-amino and 2Ј-H
substituents in the respective 1H NMR spectra.
cyclic pyrrolo[2,3-d]pyrimidines of the type 2 (R᎐H, NH etc.)
᎐
2
O
O
O
N
N
N
N
N
HN
HN
HN
O
N
N
N
R
R
Me
Me
Me
1
3
2
as correspondingly restrained analogues of N-hydroxypurines.
In previous work 6 we attempted to prepare such compounds in
order inter alia to investigate their tautomeric equilibria. The
lack of success in a variety of reactions designed to achieve
closure of the third ring was ascribed in part to angle strain
and, where it applied, to the intrinsically low reactivity of halo-
substituents at C-4 in pyrrolo[2,3-d]pyrimidines, in particular
those deactivated by a 2-amino substituent.7
In the present paper we describe the synthesis of the hom-
ologous ring system, 3 which includes the tricyclic derivative 9-
methylpyrrolo[4,3,2-de]pyrimido[4,5-c]dihydrooxazepine 34.†
† Such compounds are more correctly named according to the IUPAC
rules of nomenclature as: 2,6,8,9-tetrahydro-7-oxa-2,3,5,6-tetraaza-
benzo[cd]azulenes.
During initial attempts at methylation of 6 using dimethyl
J. Chem. Soc., Perkin Trans. 1, 1997
1171

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The 5-hydroxyethyl-7H-pyrrolo[2,3-d]pyrimidines 10, 12 and
O
O
13 were then acetylated in pyridine to give the 5-(2-acetoxy-
ethyl) compounds (14, 15, 16). Selective O-acylation of the 2-
amino-7H-pyrrolo[2,3-d]pyrimidine 13 was achieved at 0 ЊC in
the dark; solutions of compound 13 undergo rapid darkening in
light and it appears as a bright blue spot on silica TLC plates
when visualised under UV light. Attempted recrystallisation of
crude 16 also led to darkening of the solution and the forma-
tion of side products. We have not investigated this further, but
such instablity has also been reported in other 2-amino-7H-
pyrrolo[2,3-d]pyrimidines.12 Compounds 14, 15 and 16 were
then converted into the corresponding 4-chloroheterocycles
(17–19) (Scheme 3) by heating under reflux with phosphoryl
i
EtO2C
NC
Br
OMe
OMe
4
5
ii
iii
O
O
O
O
N
HN
OMe
OAc
Cl
HN
H2N
OAc
OMe
O
S
N
H
NH2
N
NH2
HN
i
7
6
N
H
R
N
N
H
R
N
Scheme 1 Reagents and conditions: i, EtCO2(CN)CHϪNaϩ, NaI,
DMF, 140 ЊC, 20 h; ii, thiourea, EtONa, EtOH, reflux, 3 h; iii, guani-
dine hydrochloride, NaOEt, ethanol, reflux
14 R = MeS
15 R = H
17 R = MeS
18 R = H
16 R = NH2
19 R = NH2
OH
O
O
O
MeN
MeS
HN
MeS
OMe
ii
N
H
N
N
NH2
8
9
20 R = MeS, R′= Ac
21 R = MeS, R′ = H
22 R = MeSO2, R′ = H
23 R = H, R′ = Ac
24 R = H, R′ = H
iii
OR′
Cl
N
iv
sulfate and base, the methylsulfanylpyrimidine 8 was formed
but in admixture with the dimethylated product 9 and the
2-methylsulfanyl-7H-pyrrolo[2,3-d]pyrimidine 10 as evidenced
by 1H NMR and mass spectral results. However, methylation of
6 with methyl iodide in DMF in the absence of base gave 10
directly and in high yield (Scheme 2). Clearly the acid formed in
iii
iii
N
R
N
25 R = NH2, R′ = Ac
26 R = NH2, R′ = H
Me
Scheme 3 Reagents and conditions: i, POCl3, PhNMe2, BzEt3NϩClϪ,
reflux; ii, NaH, MeCN, 30 min, then Mel; iii, aq. NH4OH, MeOH,
room temp., 6 h; iv, MMPP aq. EtOH, room temp.
O
O
OH
O
chloride and dimethylaniline in the presence of benzyltriethyl-
ammonium chloride. Yields were poor, not least because of the
dark decomposition products of dimethylaniline. The more
recent halogenation using triphenylphosphine–carbon tetra-
chloride, used effectively by Napoli et al.13 in the purine series,
was ineffective in the present case, whilst thionyl chloride
proved to be less efficient than phosphoryl chloride. Several
other protecting groups for the alcohol were also examined.
Thus, the p-tert-butylbenzoyl group was stable during the chlor-
ination but could not be as easily removed, whilst several silyl
protecting groups, notably even triphenylsilyl were removed to
varying degrees during the halogenation. The 4-chloro-7H-
pyrrolo[2,3-d]pyrimidines (17–19) were treated with sodium
hydride in acetonitrile followed by addition of methyl iodide to
give the corresponding 7-methyl derivatives (20, 23 and 25) in
high yield. These were subsequently deacetylated to give the
5-(2-hydroxyethyl)-7-methyl-7H-pyrrolo[2,3-d]pyrimidines (21,
24 and 26).
HN
i
OMe
HN
MeS
S
N
H
NH2
NH
N
6
10
ii
OH
O
OH
O
iii
HN
HN
N
H
S
N
H
N
H
N
11
12
OH
O
O
O
ii
HN
HN
H2N
OMe
N
H
Our earlier experience6 of 4-halogeno-7H-pyrrolo[2,3-d]-
pyrimidines had shown us that a 2-methylsulfonyl residue
would be advantageous in increasing the reactivity at C-4; it
was expected, too, to provide a residue at C-2 which could be
more readily displaced by nucleophiles for the introduction of
other functional groups. Oxidation of 21, conveniently by mag-
nesium monoperphthalate, gave the 2-methylsulfonyl derivative
22 in high yield. In order to introduce the aminooxyethyl resi-
due for the cyclisation, the alcohols 22, 24 and 26 were submit-
ted to Mitsunobu coupling with N-hydroxyphthalimide to give
the 5-(2-phthalimidooxyethyl) derivatives 27–29 (Scheme 4).
Interestingly, the amino analogue 29 was obtained as an intense
yellow solid, while in solution it was colourless. This suggested
N
H2N
N
NH2
7
13
Scheme 2 Reagents and conditions: i, MeI, DMF, room temp. 6 h; ii,
aq. HCl; iii, Raney Ni, water, reflux, 3 h
the alkylation was sufficient to activate the acetal function of
the methoxytetrahydrofuranyl residue for cyclisation.
When 6 and 7 were treated with dilute hydrochloric acid,
both cyclised in high yield to the corresponding 2-thioxo- and
2-amino-7H-pyrrolo[2,3-d]pyrimidines, 11 and 13, respectively.
The former was converted into the hypoxanthine analogue 12,
upon reduction with Raney nickel.
1172
J. Chem. Soc., Perkin Trans. 1, 1997

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In order to obtain the corresponding 2-amino derivative of
OH
ONPhth
Cl
N
Cl
N
34, we initially tried heating 33 with ammonia in dioxane in a
sealed bottle at 100 ЊC for 24 h but observed no reaction, whilst
heating in aqueous ammonia for 48 h at 120 ЊC in a sealed tube
gave unidentified decomposition products. Attempts to displace
the methylsulfonyl group with sodioacetamide were equally
unsuccessful, which may be due to ionisation of the 1-NH pro-
ton or the methylsulfonyl residue,15 thereby discouraging attack
of the nucleophile. In the former case, it is likely that the meth-
ylsulfonyl group decreases the pKa of the proton sufficiently for
this to occur and indeed we have found that in other com-
pounds where this ionisation cannot occur, displacement with
sodioacetamide proceeded readily (unpublished results). As an
alternative route to 34 we considered an analogous cyclisation
using the 5-aminooxyethyl derivative to displace a 4-(2,4-
N
N
i
N
N
R
R
Me
Me
22 R = MeSO2
24 R = H
26 R = NH2
27 R = MeSO2
28 R = H
29 R = NH2
ii
O
ONH2
HN
Cl
N
iii
N
N
N
R
N
R
N
dinitrophenylsulfanyl)- rather than
a 4-chloro-substituent.
Me
Me
Thus, 23 was converted efficiently with thiourea into the 4-
thioxo derivative 37, which was then treated with 2,4-dinitro-
fluorobenzene to give 38 and converted into the N-hydroxy-
phthalimide derivative 39. The corresponding aminooxyethyl
derivative 40 was obtained following treatment of 39 with
ammonia in dioxane and isolated by silica gel chromatography.
When 40 was heated in ethanol no evidence for cyclisation was
observed.
30 R = MeSO2
31 R = H
32 R = NH2
33 R = MeSO2
34 R = H
Scheme 4 Reagents and conditions: i, Ph3P, DEAD, PhthNOH, THF,
room temp.; ii, NH3, dioxane, room temp. 6 h; iii, EtOH, reflux 1 d for
33, THF 70 ЊC, 1 d for 34
stacking of the phthalimide and pyrrolopyrimidine rings in the
solid state; this feature had not been observed in a correspond-
ing 5-phthalimidooxymethyl derivative prepared previously.6
When the phthalimidooxy derivatives were treated with satur-
ated ammonia in dioxane for 6 h at room temperature, the
phthaloyl residue was removed. The aminooxyethyl derivatives
30–32 were observed on TLC, as slower-running products, but
were not isolated. None showed any evidence of cyclisation
under the deprotection conditions, or upon subsequent heating
of the solution. However, when 30 was heated under reflux in
ethanol, TLC indicated the appearance of a new, less polar
product 33 which was isolated in 36% yield following silica
chromatography and crystallisation from ethanol. 1H NMR
and mass spectral evidence showed that this was the desired
tricyclic compound. When the aminooxy derivative 31 was
heated in THF at 70 ЊC for 1 day in a sealed bottle, the tricyclic
N6-hydroxy-2Ј-deoxyadenosine analogue 34 was obtained
although only in 5% yield. However, the same compound could
be obtained more conveniently and in higher yield from 33. The
latter was efficiently converted into 35 by heating with hydra-
zine in ethanol, followed by oxidation of the hydrazino moiety
with mercuric oxide in ethanol14 to afford the desired com-
pound in 29% yield. The side product, 2-ethoxy-7H-pyrrolo-
[2,3-d]pyrimidine derivative 36, was obtained in 13% yield in the
reaction.
We2,16 and others17,18 have previously found that signals
attributable to both the imino and amino tautomers are ob-
1
served in the H NMR spectra of both N6-methoxy-2Ј-deoxy-
adenosine and 2-amino-N6-methoxy-2Ј-deoxyadenosine. Fur-
thermore, the ratio of the tautomers is strongly solvent depend-
ent; in a polar solvent such as DMSO, the imino tautomer
predominates, whilst in chloroform, the amino tautomer is pre-
ferred. However, the 1H NMR spectrum of 34 in both DMSO
and chloroform showed the presence of only one tautomer as
was also found for the tricyclic derivatives 33, 35 and 36. It has
been shown 18 that for N 6-methoxy-9-methyladenine, a signifi-
cant upfield shift of the 1H NMR signal corresponding to the 2-
H ring proton occurs for the imino tautomer relative to both the
corresponding amino tautomer and the parent compound, 9-
methyladenine. In addition, coupling of the 2-H with the 1-NH
proton (J 3.9 Hz) is observed for N6-methoxy-9-methyladenine.
On this basis, we have tentatively ascribed the amino tautomer
of 34 as being the major species. It is noteworthy that 1H NMR
spectral evidence suggests that 1 also appears to exist as a single
tautomer,1 but is able to pair effectively with either adenine or
guanine.3–5 Furthermore, the tautomeric equilibrium of N 6-
methoxyadenine is appreciably shifted to the amino or imino
form upon the addition of uridine or cytidine, respectively.17
1
For this reason, the H NMR data for 34 presented here is
compatible with our expectation that the analogue will base
pair effectively with either cytosine or thymine/uracil.
We are currently investigating the tautomeric state and base-
pairing properties of 34.
O
OH
S
HN
HN
N
N
N
N
R
N
Experimental
Me
Me
1H NMR spectra were recorded at 250.13 MHz or at 300.13
MHz on a Bruker WM 250 or AM300 spectrometer with
tetramethylsilane as the external standard (J values in Hz). D2O
was added to 1H NMR samples for the identification of
exchangeable protons. UV spectra were obtained using a
Perkin-Elmer Lambda 2 spectrophotometer, all samples being
dissolved in distilled water or analytical methanol (Aldrich).
Mass spectra were recorded on a Kratos MS890 instrument.
Melting points are uncorrected.
Anhydrous DMF was obtained from Aldrich. Pyridine and
acetonitrile (Rathburn) were dried by refluxing over calcium
hydride followed by distillation. THF (Merck) and dioxane
(Merck) were dried by reflux over and distillation from sodium–
benzophenone. All other reagents were obtained from Aldrich.
Silica gel column chromatography used either Kieselgel 60 (<63
37
35 R = NH2NH
36 R = EtO
NO2
NO2
O2N
O2N
OH
OR
S
S
N
N
N
N
N
N
Me
Me
39 R = NPhth
40 R = NH2
38
J. Chem. Soc., Perkin Trans. 1, 1997
1173

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µm) or Kieselgel 60 H (where indicated) from Merck. Pre-coated
silica gel F254 plates for preparative (1 mm) or thin-layer
chromatography (TLC) (Merck) were developed using one of
the following solvent systems: A, ethyl acetate–cyclohexane
(1:2); B, methanol–chloroform (1:9); C, methanol–chloroform
(2:8); D, methanol–chloroform (15:85); E, methanol–
chloroform (2:98); F, methanol–chloroform (5:95). Tetrahy-
drofuranosyl derivatives were identified with anisaldehyde solu-
tion which contained anisaldehyde (9.2 cm3), acetic acid (3.75
cm3), conc. H2SO4 (1.25 cm3) and 95% ethanol (388 cm3).
>300 ЊC (darkens 205 ЊC) (Found: C, 44.3; H, 5.4; N, 17.4.
C9H13N3SO3 requires C, 44.4; H, 5.4; N, 17.3%); RF (in B), 0.45
and 0.39 (2 diastereoisomers) (stains red with anisaldehyde/
Hϩ); δH ([2H6]-DMSO) 11.76 (1 H, br s, NH), 11.46 (1 H, br s,
NH), 6.22 (0.26 H, br s, 6a-NH2), 6.06 (1.74 H, s, 6b-NH2), 5.05
(0.13 H, d, J 3.4, 2Ј-Ha), 4.80 (0.87 H, d, J 4.7, 2Ј-Hb), 3.94–
3.80 (3 H, m, 3Ј-H and 2 × 5Ј-H), 3.33 (0.39 H, s, a-MeO), 3.21
(2.61 H, s, b-MeO), 2.50 (1 H, m, 4Ј-H) and 1.70 (1 H, m, 4Ј-H);
λmax(MeOH)/nm 203 (25 200) and 282 (18 800).
2,6-Diamino-5-(2-methoxytetrahydrofuran-3-yl)pyrimidin-4-one
7
3-Bromo-2-methoxytetrahydrofuran 4
The preparation was based on that described in ref. 10. Bromine
(320 g, 104 cm3, 2 mol) in carbon tetrachloride (200 cm3) was
added dropwise to a stirred solution of 2,3-dihydrofuran (154 g,
166 cm3, 2.2 mol) in carbon tetrachloride (200 cm3) whilst the
reaction temperature was maintained between Ϫ30 and
Ϫ40 ЊC. After a further 30 min, the resulting reaction mixture
was added dropwise to a stirred solution of sodium methoxide
(95%; 126 g, 2.2 mol) in methanol (800 cm3) at 0 ЊC. The reac-
tion mixture was then filtered through Celite and concentrated
on a rotary evaporator to ca. 600 cm3. This was then diluted
with diethyl ether (2 l) and filtered again through Celite. The
filtrate was washed with water (4 × 500 cm3), dried (Na2SO4)
and evaporated. Distillation of the residue under reduced pres-
sure through a Vigreux column gave a colourless liquid (277 g,
1.53 mol, 77%) as a mixture of cis and trans isomers;11 bp 61–
63 ЊC/12 mmHg; RF (in A), 0.85, 0.70 (stains black with
anisaldehyde/Hϩ); δH ([2H6]-DMSO) 5.09 (0.22 H, d, J 3.1,
trans-2-H), 4.85 (0.78 H, d, J 4.0, cis-2-H), 4.20–3.90 (3 H, m,
3-H and 2 × 5-H), 3.41 (0.66 H, s, trans-MeO), 3.32 (2.34 H, s,
cis-MeO) and 2.70–2.10 (2 H, m, 2 × 4-H).
To a solution of guanidine hydrochloride (10.75 g, 112.6 mmol)
in absolute ethanol (127 cm3) was added 1 mol dmϪ3 sodium
ethoxide solution (113 cm3, 113 mmol) and the resultant pre-
cipitate was filtered off. To 85 cm3 of the filtrate (40 mmol
guanidine) was added 1 mol dmϪ3 sodium ethoxide solution (40
dmϪ3, 40 mmol), followed by 5 (8.5 g, 40 mmol) in absolute
ethanol (40 cm3). The mixture was refluxed for 3 h and then
evaporated to a foam. Work-up as for 6 gave a pale brown solid
(5.10 g, 22.6 mmol, 56 %), crystallisation of which from ethanol
gave white needles, mp 202–203 ЊC (Found: C, 47.5; H, 6.2; N,
24.9. C9H14N4O3 requires C, 47.8; H, 6.2; N, 24.8%); RF (in B),
0.52 (stains red/purple with anisaldehyde/Hϩ); δH ([2H6]-DMSO)
10.16 (1 H, br s, NH), 6.17 (0.5 H, s, 6a-NH2), 6.13 (0.5 H, s, 6b-
NH2), 5.68 (2 H, br s, 2-NH2), 5.05 (0.5 H, d, J 3.4, 2Ј-H), 4.73
(0.5 H, d, J 4.7, 2Ј-H), 3.97–3.53 (3 H, m, 3Ј-H and 2 × 5Ј-H),
3.21 (1.5 H, s, MeO), 3.19 (1.5 H, s, MeO) and 1.96–1.88 (2 H,
m, 4Ј-H); λmax(MeOH)/nm 212 (25 400), 240 (5100) and 276
(12 200).
Attempted preparation of 6-amino-5-(2-methoxytetrahydro-
furan-3-yl)-2-methylsulfanylpyrimidin-4-one 8
Ethyl 2-cyano-2-(2-methoxytetrahydrofuran-3-yl)acetate 5
Sodium hydride (95%; 30.32 g, 1.2 mol) was suspended in
anhydrous DMF (350 cm3) in a 2 l, 3-necked flask and ethyl
cyanoacetate (136 cm3, 1.2 mmol) was added dropwise to it with
stirring under argon over 1 h. After a further 15 min, 3 (75 g,
0.41 mol) was added to the mixture, followed by sodium iodide
(2 g). The solution was then heated with vigorous stirring at
140 ЊC for 20 h under argon. After cooling, the reaction mixture
was diluted with water (200 cm3) and concentrated on a rotary
evaporator to ca. 300 cm3. It was then diluted with more water
(200 cm3) and extracted with diethyl ether (4 × 500 cm3). The
combined extracts were dried (Na2SO4), filtered and evapor-
ated. Distillation of the residue under reduced pressure through
a Vigreux column afforded a colourless liquid (13.28 g, 62.3
mmol, 15%). The cut bp 90–110 ЊC/0.4 mmHg was taken; RF (in
A), 0.45, 0.36 (stains yellow with anisaldehyde/Hϩ); δH ([2H6]-
DMSO) 5.00 (0.75 H, m, mixt. of trans-2-H), 4.89 (0.25 H, d,
J 2.1, cis-2-H), 4.29–4.19 (2 H, 2 q, cis/trans-CH2), 4.06–3.83
(2 H, 2 m, cis/trans-5-H), 3.39 (0.75 H, s, MeO), 3.36 (0.75
H, s, MeO), 3.35 (0.75 H, s, MeO), 3.31 (0.75 H, s, MeO),
2.78–2.70 (1 H, m, cis/trans-3-H), 2.30–1.71 (2 H, 2 m, 2 ×
cis/trans-4-H); m/z (EI) 213.1002 (Mϩ; Calc. for C10H15NO4,
213.1023).
Dimethyl sulfate (6.65 cm3, 70 mmol) was added dropwise to
a vigorously stirring solution of 1 mol dmϪ3 aq. sodium
hydroxide (70 cm3) containing 6 (15.07 g, 62 mmol). After 1 h,
the solution was filtered to give a gummy, white solid (13.92 g)
which comprised a mixture of 8, 9 and 10. A sample of 9 was
obtained following silica gel chromatography with a gradient
of 0–10% methanol in chloroform.
Compound 9 displayed; δH ([2H6]-DMSO) 11.39 (1 H, br s,
NH), 6.68 (1 H, s, 6-H), 4.48 (1 H, t, J 5.0, OH), 3.58 (2 H, t, J
7.1, OCH2), 3.27 (3 H, s, CH3N), 2.81 (2 H, t, J 7.1, OCH2CH2)
and 2.49 (3 H, S, CH3S); λmax(MeOH)/nm 221, 292; m/z (EI)
239.0727 (Mϩ; Calc. for C10H13N3O2S, 239.0747).
5-(2-Hydroxyethyl)-2-methylsulfanyl-7H-pyrrolo[2,3-d]-
pyrimidin-4-one 10
To a solution of compound 6 (14.85 g, 61 mmol) in anhydrous
DMF (100 cm3) was added methyl iodide (4.06 cm3, 65 mmol)
and the reaction mixture was stirred for 6 h at room temp.
Evaporation followed by trituration of the residue with diethyl
ether (3 × 250 cm3) gave a pale yellow solid (11.20 g, 49.8
mmol, 82%). Crystallisation of this from ethanol gave white
needles, mp 237–238 ЊC (Found: C, 46.1; H, 5.2; N, 18.4.
C9H11N3O2Sؒ0.5H2O requires C, 46.1; H, 5.2; N, 18.0%); RF (in
B), 0.33 (becomes pink/purple on plate under UV light);
δH ([2H6]-DMSO) 11.88 (1 H, br s, NH), 11.39 (1 H, br s, NH),
6.65 (1 H, d, J 1.5, 6-H), 4.51 (1 H, t, J 5.3, OH), 3.58 (1 H, m,
OCH2), 2.79 (1 H, t, J 7.2, OCH2CH2) and 2.48 (3 H, s, CH3S).
6-Amino-5-(2-methoxytetrahydrofuran-3-yl)-2-thioxo-pyrimidin-
4-one 6
To a solution of thiourea (15 g, 197 mmol) in absolute ethanol
(400 cm3) was added 1 mol dmϪ3 sodium ethoxide solution (196
cm3, 196 mmol), followed by a solution of 5 (37.28 g, 175
mmol) in absolute ethanol (100 cm3). The mixture was refluxed
for 3 h then evaporated to a foam. The residue was redissolved
in water (150 cm3) and extracted with diethyl ether (50 cm3).
The aqueous layer was neutralised with 50% aq. acetic acid, and
after a short time at 4 ЊC, a pale brown solid (19.98 g) was
precipitated. After concentration and chilling of the mixture,
a further crop (2.76 g) was obtained; yield, 22.74 g (94 mmol,
54%). Crystallisation from ethanol gave white needles, mp
5-(2-Hydroxyethyl)-2-thioxo-7H-pyrrolo[2,3-d]pyrimidin-4-one
11
Compound 6 (5.10 g, 21 mmol) was stirred in aq. hydrochloric
acid (0.2 mol dmϪ3; 125 cm3) at room temp. for 4 h and then
neutralised with dilute aq. ammonia solution to give a pale
brown solid (3.38 g). Concentration of the filtrate gave an add-
itional crop (673 mg); yield, 4.053 g (19.2 mmol, 91%). Crystal-
lisation of the crude product from water gave pale brown
needles, mp >300 ЊC (Found: C, 45.4; H, 4.3; N, 20.1.
1174
J. Chem. Soc., Perkin Trans. 1, 1997

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C8H9N3O2S requires C, 45.5; H, 4.3; N, 20.1%); RF (in C), 0.21;
δH ([2H6]-DMSO) 13.06 (1 H, br s, NH), 11.73 (1 H, br s, NH),
10.92 (1 H, br s, NH), 6.48 (1 H, s, 6-H), 4.50 (1 H, t, J 4.7, OH),
3.54 (1 H, m, OCH2) and 2.71 (1 H, t, J 7.13, OCH2CH2);
λmax(MeOH)/nm 243 (7700), 285 (9000) and 301sh.
itional water (30 cm3) and then dried in vacuo over P2O5 to give
a pale brown solid (3.05 g, 12.92 mmol, 99%). Attempts to
purify the crude product by chromatography or recrystal-
lisation led to rapid darkening of solutions, RF (in B), 0.26
(becomes green in UV light on plate); δH ([2H6]-DMSO) 10.68 (1
H, br s, NH), 10.15 (1 H, br s, NH), 6.42 (1 H, s, 6-H), 5.97 (2
H, br s, NH2), 4.21 (2 H, t, J 7.1, OCH2), 3.54 (2 H, m,
OCH2CH2) and 1.96 (3 H, s, CH3CO); δC([2H6]-DMSO) 159.62
(C-4), 152.17 (C-2), 151.34 (C-8), 115.31 (C-5), 114.24 (C-6),
99.02 (C-9), 62.27 (CH2) and 30.16 (CH2); m/z (EI) 236.0908
(Mϩ; Calc. for C10H12N4O3, 236.0909).
5-(2-Hydroxyethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-one 12
Compound 11 (528 mg, 2.5 mmol), was refluxed with Raney
nickel (2 cm3) in water (60 cm3) containing aq. ammonia (35%
w/v; 5 cm3). After 3 h, the solution was filtered hot, and the
catalyst washed with hot 2% aq. ammonia solution (3 × 100
cm3). Evaporation of the combined filtrates afforded a white
solid (414 mg, 2.31 mmol, 92%), RF (in B), 0.14; δH ([2H6]-
DMSO) 11.61 (2 H, br s, 2 NH), 7.76 (1 H, s, 2-H), 6.80 (1 H, s,
6-H), 5.02 (1 H, br s, OH), 3.61 (2 H, t, J 7.1 , CH2) and 2.83 (2
H, t, J 7.1, CH2); m/z (EI) 179.0693 (Mϩ; Calc. for C8H8N4O2,
179.0695).
5-(2-Acetoxyethyl)-4-chloro-2-methylsulfanyl-7H-pyrrolo[2,3-
d]pyrimidine 17
Compound 14 (3.2 g, 12 mmol) and benzyl(triethyl)ammonium
chloride (5.1 g, 24 mmol), dried in a vacuum oven at 70 ЊC over
P2O5 overnight, were suspended in dry acetonitrile (65 cm3).
Dry dimethylaniline (2.13 cm3, 12 mmol) was added to the sus-
pension followed by freshly distilled phosphoryl chloride (6.75
cm3, 72 mmol). The mixture was refluxed for 1.5 h after which
the excess of phosphoryl chloride was removed by distillation.
The resulting gum was added to crushed ice and after 0.5 h the
mixture was extracted with chloroform (500 cm3). The organic
phase was washed with saturated aq. sodium hydrogen carbon-
ate (50 cm3), dried (Na2SO4) and evaporated. Silica gel column
chromatography (52 × 400 mm) of the residue with chloroform
as the eluent afforded a white solid (992 mg, 3.47 mmol, 29%);
RF (in F), 0.65; δH ([2H6]-DMSO) 12.24 (1 H, br s, NH), 7.38 (1
H, s, 6-H), 4.26 (2 H, t, J 6.8, OCH2), 3.08 (2 H, t, J 6.8,
OCH2CH2), 2.52 (3 H, s, CH3S) and 1.98 (3 H, s, CH3CO);
λmax(MeOH)/nm 221, 252 and 311; m/z (EI) 285.0339 (Mϩ;
Calc. for C11H12ClN3O2S, 285.0356).
2-Amino-5-(2-hydroxyethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-one
13
Compound 7 (5.65 g, 25 mmol) was stirred in aq. hydrochloric
acid (0.2 mol dmϪ3; 150 cm3) at room temp. for 2 h. Work-up as
for 11 gave pale brown flakes (4.225 g, 21.8 mmol, 87%), mp
251.5–253 ЊC (Found: C, 45.0; H, 5.7; N, 27.0. C8H10N4O2ؒH2O
requires C, 45.3; H, 5.7; N, 26.4%); RF (in D) 0.12 (becomes
purple in UV light on plate); δH ([2H6]-DMSO) 10.67 (1 H, br s,
NH), 10.15 (1 H, br s, NH), 6.38 (1 H, d, J 2.0, 6 H), 5.99 (2 H,
br s, NH2), 4.63 (1 H, t, J 5.3, OH), 3.58 (2 H, m, OCH2) and
2.73 (2 H, t, J 7.1, OCH2CH2); δC([2H6]-DMSO) 159.62 (C-4),
152.17 (C-2), 151.34 (C-8), 115.31 (C-5), 114.24 (C-6), 99.02
(C-9), 62.27 (CH2) and 30.16 (CH2); λmax(MeOH)/nm 220
(18 500), 260 (9700) and 280 infl. (7100).
5-(2-Acetoxyethyl)-2-methylsulfanyl-7H-pyrrolo[2,3-d]-
pyrimidin-4-one 14
5-(2-Acetoxyethyl)-4-chloro-7H-pyrrolo[2,3-d]pyrimidine 18
Compound 15 (1.45 g, 7.5 mmol), benzyl(triethyl)ammonium
chloride (3.42 g, 15 mmol), dry dimethylaniline (1.37 cm3, 10.5
mmol) and freshly distilled phosphoryl chloride (3.5 cm3, 37.5
mmol) were heated under reflux for 1 h in dry acetonitrile (40
cm3) as for 17. Excess of phosphoryl chloride was then removed
by distillation, crushed ice added and after 1 h the pH of the
solution was adjusted to 2 by addition of dilute aq. ammonia.
The mixture was left in the refrigerator overnight after which
the precipitate was filtered off and washed with water. Silica gel
chromatography (32 × 150 mm) eluting with a gradient of
0–1% methanol in chloroform gave a white solid (573 mg, 2.72
mmol, 36%); RF (in B), 0.35; δH ([2H6]-DMSO) 12.34 (1 H, br s,
NH), 8.52 (1 H, s, 2-H), 7.52 (1 H, s, 6-H), 4.28 (2 H, t, J 6.7,
OCH2), 3.54 (2 H, t, J 6.7, OCH2CH2) and 1.98 (3 H, s,
CH3CO); λmax(MeOH)/nm 225, 269 and 295; m/z (EI) 239.0462
(Mϩ; Calc. for C10H10ClN3O2, 239.0476).
To a suspension of compound 10 (11.25 g, 50 mmol) in dry
pyridine (500 cm3) was added acetic anhydride (8 cm3, 85
mmol). The mixture was stirred overnight at room temp. in the
dark after which it was evaporated. Co-evaporation of the
residual pyridine with water, followed by recrystallisation of the
residue from acetone–water (9:1) gave white needles (7.88 g,
29.5 mmol, 59%); RF (in B), 0.56; δH ([2H6]-DMSO) 11.99 (1 H,
br s, NH), 11.53 (1 H, br s, NH), 6.73 (1 H, s, 6-H), 4.21 (2 H, t, J
7.0, OCH2), 2.91 (2 H, t, J 7.0, OCH2CH2), 2.48 (3 H, s, CH3S)
and 1.96 (3 H, s, CH3CO); λmax(MeOH)/nm 221 and 287; m/z
(EI) 267.0674 (Mϩ; Calc. for C11H13N3O3S, 267.0696).
5-(2-Acetoxyethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-one 15
Compound 12 (313 mg, 1.75 mmol) was dissolved in dry pyri-
dine (20 cm3) and acetic anhydride (0.33 cm3, 3 mmol) was
added to the solution. After 2 h, silica TLC indicated the reac-
tion to be complete, and the solution was evaporated. Crystal-
lisation of the residue from aq. ethanol gave white needles (254
mg, 1.14 mmol, 65%); mp 236.5–237.5 ЊC (softens 229 ЊC)
(Found: C, 54.1; H, 5.0; N, 19.0. C10H11N3O3 requires C, 54.3;
H, 5.0; N, 19.0); RF (in B), 0.33; δH ([2H6]-DMSO) 11.80–11.57
(2 H, 2 br s, 2 NH), 7.75 (1 H, s, 2-H), 6.84 (1 H, s, 6-H), 4.24 (2
H, t, J 7.1, OCH2), 2.96 (2 H, t, J 7.1, OCH2CH2) and 1.97 (3 H,
s, CH3CO); λmax(MeOH)/nm 217 and 264.
5-(2-Acetoxyethyl)-2-amino-4-chloro-7H-pyrrolo[2,3-d]-
pyrimidine 19
Compound 16 (2.29 g, 11 mmol), benzyl(triethyl)ammonium
chloride (4.70 g, 22 mmol), dry dimethylaniline (1.95 cm3, 15
mmol) and freshly distilled phosphoryl chloride (6.2 cm3, 66
mmol) were heated under reflux in dry acetonitrile (55 cm3) for
30 min. A yellow solid (1.05 g, 4.64 mmol, 42%) was obtained
following work-up as for 18; RF (in B), 0.28, (in E) and 0.12;
δH ([2H6]-DMSO) 11.26 (1 H, br s, NH), 6.92 (1 H, s, 6-H), 6.45
(2 H, br s, NH2), 4.21 (2 H, t, J 6.9, OCH2), 2.98 (2 H, t, J 6.7,
OCH2CH2) and 1.98 (3 H, s, CH3CO); λmax(MeOH)/nm 234
and 320; m/z (EI) 254.0571 (Mϩ; Calc. for C10H11ClN4O2,
254.0787).
2-Amino-5-(2-acetoxyethyl)-7H-pyrrolo[2,3-d]pyrimidin-4-one
16
Compound 13 (2.53 g, 13 mmol) was suspended in dry pyridine
(130 cm3) at 0 ЊC in the dark and acetic anhydride (1.53 cm3,
16.25 mmol) was added to it. The mixture was stirred in the
dark at 0 ЊC overnight after which additional acetic anhydride
(0.5 cm3, 5.3 mmol) was added. After stirring of the mixture
overnight, the reaction being complete, the solution was evapor-
ated. Residual pyridine was removed by co-evaporation with
toluene and then water. Water (50 cm3) was then added to the
residue and the product was filtered off, washed with an add-
4-Chloro-5-(2-hydroxyethyl)-2-methylsulfanyl-7-methyl-7H-
pyrrolo[2,3-d]pyrimidine 21
A stirred suspension of 17 (1.50 g, 5.24 mmol) in dry
acetonitrile (70 cm3) under argon was treated with NaH (60% in
oil; 220 mg, 5.5 mmol). After 30 min, methyl iodide (626 mm3,
J. Chem. Soc., Perkin Trans. 1, 1997
1175

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10 mmol) was added to the mixture and stirring continued for a
further 30 min. The solution was evaporated in vacuo and the
residue partioned between chloroform (500 cm3) and water (100
cm3). The organic phase was separated and evaporated and the
crude product purified by silica gel chromatography (60 H,
32 × 200 mm) eluting with chloroform. The N-methyl-acetoxy
derivative, 20 was obtained as a colourless solid, RF (in F), 0.50;
δH ([2H6]-DMSO), 7.40 (1 H, s, 6-H), 4.24 (2 H, t, J 6.9, OCH2),
3.72 (3 H, s, CH3N), 3.08 (2 H, t, J 6.9, OCH2CH2), 2.56 (3 H, s,
CH3S) and 1.99 (3 H, s, CH3CO).
Compound 20 was then suspended in MeOH–concentrated
aq. ammonia (1:1; 300 cm3) and stirred 6 h at room temp.
Evaporation followed by recrystallisation of the residue from
chloroform gave colourless needles 21 (1.10 g. 4.26 mmol, 81%);
RF (in F) 0.40; δH ([2H6]-DMSO) 7.32 (1 H, s, 6-H), 4.70 (1 H, t, J
5.4, OH), 3.71 (3 H, s, CH3N), 3.62 (2 H, m, OCH2) and 2.91 (2
H, t, J 7.2, OCH2CH2); λmax(MeOH)/nm 257 and 285; m/z (EI)
257.0384 (Mϩ; Calc. for C10H12ClN3OS, 257.0407).
239, 269 and 321; m/z (EI) 226.0616 (Mϩ; Calc. for C9H11-
ClN4O, 226.0637).
4-Chloro-7-methyl-2-methylsulfonyl-5-(2-phthalimidooxyethyl)-
7H-pyrrolo[2,3-d]pyrimidine 27
Compound 22 (3.47 g, 12 mmol) was suspended in dry THF
(200 cm3) containing triphenylphosphine (6.29 g, 24 mmol) and
N-hydroxyphthalimide (3.89 g, 24 mmol). Diethyl azodicarb-
oxylate (3.77 cm3, 24 mmol) was then added to the solution
after which it was stirred for 3 h at room temp. The mixture was
then evaporated and the residue dissolved in chloroform (40
cm3) and extracted with saturated aq. sodium hydrogen
carbonate (3 × 20 cm3). The organic layer was evaporated and
the residue triturated with diethyl ether (30 cm3). Crystallisation
from ethanol gave white needles (3.69 g, 8.49 mmol, 71%); mp
240–241 ЊC (Found: C, 49.9; H, 3.4; N, 12.8. C18H15ClN4SO5
requires C, 49.2; H, 3.5; N, 12.9); RF (in F), 0.65; δH ([2H6]-
DMSO) 8.00 (1 H, s, 6-H), 7.86 (4 H, s, phth-H), 4.46 (2 H, t,
J 6.7, OCH2),3.88 (3 H, s, CH3N), 3.41 (3 H, s, CH3SO2) and
3.35 (2 H, t, J 6.9, OCH2CH2); λmax(MeOH)/nm 219 and 240.
4-Chloro-7-methyl-2-methylsulfonyl-5-(2-hydroxyethyl)-7H-
pyrrolo[2,3-d]pyrimidine 22
To compound 21 (750 mg, 3 mmol) in ethanol (60 cm3) was
added magnesium monoperphthalate (3.0 g, 6 mmol) in water
(15 cm3) and the solution stirred at room temp. overnight. The
reaction mixture was then evaporated and the residue par-
titioned between chloroform (500 cm3) and saturated aq.
sodium hydrogen carbonate (100 cm3). The organic phase was
separated, dried (Na2SO4) and evaporated to give a white foam
(510 mg, 1.77 mmol, 59%); mp 157–158 ЊC; RF (in F), 0.17
(fluorescent); δH ([2H6]-DMSO) 7.82 (1 H, s, 6-H), 4.76 (1 H, br
s, OH), 3.87 (3 H, s, CH3N), 3.67 (2 H, t, J 6.9, OCH2), 3.41 (3
H, s, CH3SO2) and 3.02 (2 H, t, J 6.9, OCH2CH2); λmax(MeOH)/
nm 242 and 280; m/z (EI) 289.0305 (Mϩ; Calc. for C10H12-
ClN3O3S, 289.0287).
4-Chloro-7-methyl-5-(2-phthalimidooxyethyl)-7H-pyrrolo[2,3-d]-
pyrimidine 28
Compound 24 (560 mg, 2.66 mmol) was suspended in dry THF
(40 cm3) containing triphenylphosphine (790 mg, 3 mmol) and
N-hydroxyphthalimide (400 mg, 3 mmol). Diethyl azodicarbo-
xylate (470 mm3) was then added to the solution after which it
was stirred for 2 h at room temp. After this time the product was
worked up as for 27.The product crystallised from ethanol as
white needles (740 mg, 2.09 mmol, 78%); mp 188–189 ЊC
(Found: C, 54.6; H, 3.5; N, 15.0. C17H13N4O3ؒH2O requires C,
54.6; H, 3.5; N, 15.0%); RF (in E), 0.61; δH ([2H6]-DMSO) 8.58
(1 H, s, 2-H), 7.86 (4 H, s, phth-H), 7.70 (1 H, s, 6-H), 4.43 (2 H,
t, J 6.9, OCH2), 3.80 (3 H, s, CH3N) and 3.30 (2 H, t, J 6.9,
OCH2CH2); λmax(MeOH)/nm 250 and 287.
4-Chloro-5-(2-hydroxyethyl)-7-methyl-7H-pyrrolo[2,3-d]
pyrimidine 24
2-Amino-4-chloro-7-methyl-5-(2-phthalimidooxyethyl)-7H-
pyrrolo[2,3-d]pyrimidine 29
Compound 18 (925 mg, 3.86 mmol) was treated with NaH
(60% in oil, 160 mg, 4.0 mmol) and methyl iodide (470 mm3,
7.5 mmol) in dry acetonitrile (50 cm3) as for the preparation
of 20, to give 23 as a white solid (850 mg, 3.35 mmol, 87%);
RF (in C), 0.87; δH ([2H6]-DMSO) 8.57 (1 H, s, 2-H), 7.57 (1
H, s, 6-H), 4.28 (2 H, d, J 6.8, OCH2), 3.80 (3 H, s, CH3N),
3.16 (2 H, t, J 6.8, OCH2CH2) and 1.99 (3 H, s, CH3CO).
Compound 23 (850 mg, 3.35 mmol) was deacetylated as for
20 and the crude product purified by silica gel chroma-
tography (32 × 250 mm) eluting with 3% methanol in chloro-
form. A white solid (560 mg, 2.65 mmol, 79%) was obtained;
RF (in C), 0.66; δH ([2H6]-DMSO) 8.55 (1 H, s, 2-H), 7.49 (1
H, s, 6-H), 4.65 (1 H, br s, OH), 3.78 (3 H, s, CH3N), 3.67 (2
H, d, J 6.8, OCH2) and 2.98 (2 H, t, J 6.8, OCH2CH2);
λmax(MeOH)/nm 230, 271 and 305; m/z (EI) 211.0511 (Mϩ;
Calc. for C9H10ClN3O, 211.0527).
Compound 26 (340 mg, 1.5 mmol) was suspended in dry THF
(25 cm3) containing triphenylphosphine (447 mg, 1.7 mmol)
and N-hydroxyphthalimide (225 mg, 1.7 mmol). Diethyl azo-
dicarboxylate (300 mm3, 1.9 mmol) was then added to the solu-
tion after which it was stirred for 3 h at room temp. After this
time the product was worked up as for 27. Crystallisation of the
crude product from ethanol gave yellow needles (90 mg, 1.05
mmol, 69%); mp 254.5–255.5 ЊC (Found: C, 54.6; H, 3.7; N,
19.0. C17H14ClN5O3 requires C, 54.9; H, 3.8; N, 18.8%); RF (in
C), 0.10; δH ([2H6]-DMSO) 7.86 (4 H, m, 4 phth-H), 7.62 (1 H, s,
6-H), 6.71 (2 H, br s, NH2), 4.35 (2 H, m, OCH2), 3.53 (3 H, s,
CH3N) and 3.14 (2 H, m, OCH2CH2); λmax(MeOH)/nm 291 and
318.
9-Methyl-2-methylsulfonylpyrrolo[4,3,2-de]pyrimido[4,5-c]-
dihydrooxazepine 33‡
2-Amino-4-chloro-5-(2-hydroxyethyl)-7-methyl-7H-pyrrolo[2,3-
d]pyrimidine 26
Compound 27 (300 mg, 0.70 mmol) was stirred in a solution of
saturated ammonia in dry dioxane (30 cm3) in a sealed bottle
for 6 h. Silica TLC showed complete conversion to 30 [RF (in
F), 0.17] after this time. The solution was evaporated to dryness
and the residue refluxed in absolute ethanol (50 cm3) for 24 h.
Evaporation, followed by silica gel chromatography (60 H,
32 × 70 mm) in chloroform and crystallisation from ethanol
gave white needles (67 mg, 0.25 mmol, 36%); mp 221–222 ЊC
(Found: C, 44.4; H, 4.4; N, 21.0. C10H12N4SO3 requires C, 44.8;
H, 4.5; N, 20.9%); RF (in B), 0.64; δH ([2H6]-DMSO) 11.30 (1 H,
br s, NH), 7.36 (1 H, s, 6-H), 4.34 (2 H, m, CH2O), 3.77 (3 H, s,
CH3N), 3.30 (3 H, s, CH3SO2) and 2.98 (2 H, t, J 5.3, CH2CH2);
Compound 19 (600 mg, 2.36 mmol) was treated with NaH (60%
in oil, 100 mg, 2.5 mmol) and methyl iodide (313 mm3, 5 mmol)
in dry acetonitrile (30 cm3) as for the preparation of 20. The
crude product was purified by silica gel chromatography (60 H,
20 × 200 mm) eluting with chloroform to give 25 as a white
solid (470 mg, 1.75 mmol, 74%); RF (in E), 0.34; δH ([2H6]-
DMSO) 6.84 (1 H, s, 6-H), 6.35 (2 H, br s, NH2), 3.61 (2 H, t
J 7.1, OCH2), 2.83 (2 H, t J 7.1, OCH2CH2) and 1.98 (3 H, s,
CH3CO). Compound 25 (470 mg, 1.75 mmol) was deacetylated
as for 20 and the crude product crystallised from chloroform to
give colourless needles (350 mg, 1.55 mmol, 88%); RF (in E),
0.14; δH ([2H6]-DMSO) 6.89 (1 H, s, 6-H), 6.57 (2 H, br s, NH2),
4.65 (1 H, t, J 5.4, OH), 3.60 (2 H, m, OCH2), 3.52 (3 H, s,
CH3N) and 2.82 (2 H, t, J 7.2, OCH2CH2); λmax(MeOH)/nm
‡ Such compounds are more correctly named according to the IUPAC
rules of nomenclature as: 2,6,8,9-tetrahydro-7-oxa-2,3,5,6-tetraaza-
benzo[cd]azulenes..
1176
J. Chem. Soc., Perkin Trans. 1, 1997

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δH (CDCl3) 8.29 (1 H, br s, NH), 7.03 (1 H, s, 6-H), 4.48 (2 H, m,
OCH2), 3.88 (3 H, s, CH3N), 3.33 (3 H, s, CH3SO2) and 3.07 (2
H, t, J 5.5, OCH2CH2); λmax(MeOH)/nm 228 (1900), 280 (1800)
and 310 (8900); m/z (EI) 268.0631 (Mϩ; Calc. for C10H12N4O3S,
268.0630).
2,4-dinitrofluorobenzene (730 mg, 490 mm3, 0.4 mmol). The
reaction mixture was stirred for 40 min at room temp. and then
evaporated. The residue was dissolved in chloroform (50 cm3)
and the solution washed with saturated aq. sodium hydrogen
carbonate (25 cm3), saturated brine (25 cm3), water (25 cm3),
dried (Na2SO4) and evaporated. The pure product was obtained
as a yellow solid (71 mg, 0.19 mmol, 42%) after silica gel
chromatography (25 × 150 mm) eluting with chloroform; RF (in
F), 0.6; δH ([2H6]-DMSO) 8.89 [1 H, s, 3-H-C6H3(NO2)2], 8.57 (1
H, s, 2-H), 8.40 [1 H, d J 8.8, 5-H-C6H3(NO2)2], 7.79 [1 H, d J
8.8, 6-H-C6H3(NO2)2], 7.51 (1 H, s, 6-H), 4.65 (1 H, t, J 5.3,
OH), 3.79 (3 H, s, CH3N), 3.66 (2 H, t, J 6.2, OCH2) and 2.96 (2
H, t, J 6.9, OCH2CH2); λmax(MeOH)/nm 228, 303 and 354; m/z
(EI) 375.0653 (Mϩ; Calc. for C15H13N5O5S, 375.0637).
9-Methylpyrrolo[4,3,2-de]pyrimido[4,5-c]dihydrooxazepine 34‡
Method
A
{from 9-methyl-2-hydrazinopyrrolo[4,3,2-de]-
pyrimido[4,5-c]dihydrooxazepine 35}.‡ Compound 35 (125 mg,
570 µmol) was heated under reflux in absolute ethanol (10 cm3)
and mercury() oxide (494 mg, 2.28 mmol) added in four por-
tions over 3 h. After a further 1 h, the reaction mixture was
filtered through Celite; the material removed by the filtrate was
then washed with hot ethanol (100 cm3). The combined filtrates
were evaporated and the residue purified by silica gel chroma-
tography (60 H, 22 × 80 mm) eluting with chloroform and then
a gradient of 0–1% methanol in chloroform. A white solid (31
mg, 164 µmol, 29%) was obtained; RF (in B), 0.47; δH ([2H6]-
DMSO) 10.56 (1 H, br s, NH), 8.20 (1 H, s, 2-H), 7.13 (1 H, s, 6-
H), 4.29 (2 H, t, J 5.4, OCH2), 3.70 (3 H, s, CH3N) and 2.93 (2
H, t, J 5.4, OCH2CH2); δH (CDCl3) 11.88 (1 H, br s, NH) 8.35 (1
H, s, 2-H), 6.78 (1 H, s, 6-H), 4.39 (2 H, t, J 5.6, OCH2), 3.75 (3
H, s, CH3N) and 2.97 (2 H, t, J 5.6, OCH2CH2); λmax(MeOH)/
nm 270 and 300; m/z (EI) 190.085 793 (Mϩ; Calc. for C9H10N4O,
190.085 461).
The faster-running 2-ethoxy-compound 36 (18 mg, 76 µmol,
13%) was also obtained, as a white solid; RF (in B), 0.87;
δH ([2H6]-DMSO) 10.49 (1 H, br s, NH), 7.04 (1 H, s, 6-H), 4.27
(4 H, m, OCH2 and CH3CH2O), 3.64 (3 H, s, CH3N), 2.87 (2 H,
t, J 5.4, OCH2CH2) and 1.27 (3 H, t, J 6.3, CH3CH2O); m/z
(FAB) 235 (M ϩ 1)ϩ and 205 (M Ϫ Et)ϩ.
Method B {from 5-(2-aminooxyethyl)-4-chloro-7-methyl-7H-
pyrrolo[2,3-d]pyrimidine 31}. Compound 31 (100 mg, 0.58
mmol) was dissolved in THF (2 cm3) and heated at 70 ЊC over-
night in a sealed bottle. The mixture was evaporated and the
residue purified by silica-gel chromatography (10 × 150 mm)
eluting with chloroform. The initial UV-absorbing fraction was
purified further on a silica gel TLC-plate developed with
chloroform. A white solid was obtained (6 mg, 0.03 mmol, 5%)
which was identical by silica TLC and NMR to 34 prepared by
method A.
4-(2,4-Dinitrophenylsulfanyl)-5-(2-phthalimidooxyethyl)-7-
methyl-7H-pyrrolo[2,3-d]pyrimidine 39
Compound 38 (142 mg, 0.38 mmol) was suspended in dry THF
(6 cm3) containing triphenylphosphine (113 mg, 0.43 mmol)
and N-hydroxyphthalimide (57 mg, 0.43 mmol). Diethyl azodi-
carboxylate (67 mm3) was then added to the reaction mixture
after which it was stirred for 2 h at room temp. The solution was
then evaporated and the residue triturated with diethyl ether
(2 × 20 cm3); after this it was dissolved in chloroform (300 cm3)
and extracted with water (2 × 50 cm3). The combined extracts
were dried (Na2SO4), evaporated and the crude product purified
by silica gel chromatography (25 × 150 mm) eluting with
chloroform. A yellow solid (160 mg, 0.31 mmol, 81%) was
obtained, mp >300 ЊC (Found: C, 51.8; H, 3.0; N, 15.7.
C10H12N4SO3 requires C, 51.3; H, 3.4; N, 15.6%); RF (in F),
0.85; δH ([2H6]-DMSO) 8.87 [1 H, d, J 2.5, 3-H-C6H3(NO2)2],
8.65 (1 H, s, 2-H), 8.35 [1 H, dd, J 8.8 and 2.5, 5-H-C6H3-
(NO2)2], 7.81 (4 H, br s, phth), 7.76 [1 H, d, J 8.8, 6-H-C6-
H3(NO2)2], 7.81 (1 H, s, 6-H), 4.36 (2 H, t, J 7.3, OCH2), 3.82 (3
H, s, CH2N) and 3.35 (2 H, t, J 7.3, OCH2CH2); λmax(MeOH)/
nm 223 and 300.
4-(2,4-Dinitrophenylsulfanyl)-5-(2-aminooxyethyl)-7-methyl-
7H-pyrrolo[2,3-d]pyrimidine 40
Compound 38 (196 mg, 0.38 mmol) was dissolved in a saturated
solution of ammonia in dioxane (100 cm3) and the mixture
stirred in sealed flask at room temp. overnight. The reaction
mixture was then evaporated. A yellow solid (137 mg, 0.35
mmol, 93%) was obtained following silica gel chromatography
(25 × 150 mm) eluting with chloroform; RF (in F), 0.35;
δH ([2H6]-DMSO) 8.89 [1 H, s, 3-H-C6H3(NO2)2], 8.59 (1 H, s,
2-H), 8.39 [1 H, d, J 8.8, 5-H-C6H3(NO2)2], 7.76 [1 H, d, J 8.8,
6-H-C6H3(NO2)2], 7.51 (1 H, s, 6-H), 6.20 (1 H, br s, ONH2),
3.79 (3 H, s, CH3), 3.74 (2 H, t, J 6.7, OCH2) and 3.35 (2 H, t, J
6.7, OCH2CH2); m/z (EI) 375.0639 (Mϩ; Calc. for C15H13N5O5S,
375.0656). Attempts to cyclise this compound to 34 under a
variety of conditions failed.
9-Methyl-2-hydrazinopyrrolo[4,3,2-de]pyrimido[4,5-c]dihydro-
oxazepine 35‡
Compound 33 (250 mg, 0.93 mmol) was heated in a sealed
bottle at 100 ЊC with anhydrous hydrazine (2 cm3, 63.7 mmol) in
absolute ethanol (25 cm3) for 36 h. Storage of the mixture over-
night at 4 ЊC gave white needles (174 mg, 0.79 mmol, 85%); RF
(in B), 0.18 streaks; δH ([2H6]-DMSO) 10.16 (1 H, br s, NH), 7.27
(1 H, s, NH2NH), 6.69 (1 H, s, 6-H), 4.23 (2 H, t, J 5.3, OCH2),
3.99 (2 H, br s, NH2NH) 3.55 (3 H, s, CH3N) and 2.84 (2 H, t, J
5.3, OCH2CH2); m/z (EI) 220.1072 (Mϩ; Calc. for C9H12N6O,
220.1073).
Acknowledgements
We are very grateful to Dr S. P. Langston for contributing to the
experimental work. The work was supported by the Medical
Research Council (Human Genome Mapping Project)
(D. M. W. and D. M. B.) and by INTAs (D. Y.).
5-(2-Hydroxyethyl)-7-methyl-7H-pyrrolo[2,3-d]pyrimidine-4-
thione 37
Compound 23 (423 mg, 2 mmol) and thiourea (170 mg, 2.25
mmol) were heated under reflux in absolute ethanol (20 cm3) for
1 h. The mixture was then evaporated and the crude product
recrystallised from chloroform to give yellow needles (350 mg,
1.67 mmol, 84%); RF (in F) 0.3; δH ([2H6]-DMSO) 13.06 (1 H, s,
NH), 7.97 (1 H, s, 2-H), 7.08 (1 H, s, 6-H), 4.44 (1 H, br s, OH),
3.67 (3 H, s, CH3N), 3.65 (2 H, t J 6.9, OCH2) and 3.12 (2 H, t, J
6.9, OCH2CH2); λmax(MeOH)/nm 247 and 294; m/z (EI)
209.0625 (Mϩ; Calc. for C9H11N3OS, 209.0623).
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J. Chem. Soc., Perkin Trans. 1, 1997
1177

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Paper 6/06472H
Received 19th September 1996
Accepted 6th November 1996
1178
J. Chem. Soc., Perkin Trans. 1, 1997