Pyrrolo[2,3-d]pyrimidine β-L-nucleosides containing 7-deazaadenine, 2-amino-7-deazaadenine, 7-deazaguanine, 7-deazaisoguanine, and 7-deazaxanthine

Article abstract of DOI:10.1135/cccc20060956

The synthesis and properties of 7-deazapurine β-L-nucleosides are described. The stereoselective glycosylation of the anions of 2-amino-6-chloro-7-deazapurines 9a, 9b or 6-chloro-7-deazapurines 13a, 13d with 3,5-di-O-(4-methylbenzoyl)-2-deoxy-α-L-erythro-

Full text of DOI:10.1135/cccc20060956

956
Seela, Peng:
PYRROLO[2,3-d]PYRIMIDINE β-L-NUCLEOSIDES CONTAINING
7-DEAZAADENINE, 2-AMINO-7-DEAZAADENINE, 7-DEAZAGUANINE,
7-DEAZAISOGUANINE, AND 7-DEAZAXANTHINE
a,b
Frank SEELAa1,b1,* and Xiaohua PENG
a
Laboratorium für Organische und Bioorganische Chemie, Universität Osnabrück,
Barbarastr. 7, D-49069 Osnabrück, Germany; e-mail: frank.seela@uni-osnabrueck.de
Laboratory of Bioorganic Chemistry and Chemical Biology, Center for Nanotechnology,
Heisenbergstrasse 11, D-48149 Münster, Germany; e-mail: seela@uni-muenster.de
1
b
1
Received March 15, 2006
Accepted April 26, 2006
This article is dedicated to Professor Antonín Holý, a good friend and a great scientist, on the occasion
of his 70th birthday.
Th e syn th esis an d properties of 7-deazapurin e β-L-n ucleosides are described. Th e stereo-
selective glycosylation of th e an ion s of 2-am in o-6-ch loro-7-deazapurin es 9a, 9b or 6-ch loro-
7-deazapurin es 13a, 13d with 3,5-di-O-(4-m eth ylben zoyl)-2-deoxy-α-L-erythro-pen tofuran osyl
ch loride (8) furn ish ed th e β-L-2′-deoxyribon ucleosides 1–4. Th e syn th esis of β-L-ribon ucle-
osides 5–7 used th e Silyl–Hilbert–Joh n son reaction (TMSOTf/BSA/MeCN) perform ed un der
Vorbrüggen con dition s for th e glycosylation of 7-h alogen ated 6-ch loro-2-pivalam ido-
7-deazapurin es 17b –17d with 1-O-acetyl-2,3,5-tri-O-ben zoyl-L-ribofuran ose (16). Sin gle-
crystal X-ray an alyses were perform ed an d CD spectra were m easured to assign th e con figu-
ration . Th e an tiviral activity again st selected DNA an d RNA viruses is reported.
Keyw ord s: Nucleosides; Purin es; 7-Deazapurin es; Pyrrolo[2,3-d]pyrim idin es; β-L-2′-Deoxy-
ribon ucleosides; β-L-Ribon ucleosides; Nucleobase an ion glycosylation ; NMR spectroscopy;
CD spectroscopy; An tiviral activity.
Th e first L-n ucleoside (β-L-dT) was syn th esized by Šm ejkal an d Šorm in
1964 1a; in th e sam e year Acton , Ryan , an d Goodm an described β-L-aden o-
sin e1b. Related β-L-ribon ucleosides were reported by Sh im izu in 1967 2a an d
by Holý an d Šorm in 1969 2b. It was believed th at D-n ucleosides are always
m ore active th an th e L-en an tiom ers an d little atten tion h as been given to
th e L-n ucleosides. Th e discovery of th e an tiviral activity of 3TC, wh ich is
m ore active an d less toxic th an its D-coun terpart, attracted th e in terest in
th e ph arm acological activity of L-n ucleosides3–8. Th eir an tiviral activity is
som etim es com parable or even h igh er th an th at of th eir D-en an tiom ers3,7,8
.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977
© 2006 Institute of Organic Chemistry and Biochemistry
doi:10.1135/cccc20060956

Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
957
It was foun d th at cellular kin ases are able to ph osph orylate L-n ucleosides to
th eir triph osph ates. A better toxicological profile an d a greater m etabolic
stability are observed in several cases3. L-Nucleosides an d th eir an alogues
h ave becom e effective drugs for th e treatm en t of viral diseases. A n um ber of
3,6,7
th em , such as lam ivudin e (3TC) an d FTC
are com m ercialized; oth ers
like L-dT an d L-FMAU are expected to get approval by th e FDA 3,7a
.
A n um ber of 7-deazapurin e (pyrrolo[2,3-d]pyrim idin e) β-D-n ucleosides,
such as tubercidin , toyocam ycin , san givam ycin , 5′-deoxy-7-iodotubercidin ,
an d queuosin e, exh ibit a broad spectrum of biological activity9–12 (purin e
n um berin g is used th rough out th e gen eral section an d system atic n um ber-
in g in Experim en tal). Recen tly, a n ew class of 7-deazapurin e β-D-ribo-
n ucleosides with a m eth yl group ‘up’ in th e 2′-position was discovered
sh owin g stron g in h ibition of th e h epatitis C virus growth 13. Th erefore, we
becam e in terested in com bin in g th e favorable properties of th e 7-deaza-
purin e system with a β-L-sugar m oiety th ereby gen eratin g n ew m olecules
with a low toxicity profile. Up to n ow on ly very few reports h ave appeared
on th e syn th esis an d properties of 7-deazapurin e β-L-n ucleosides14,15. Th is
prom pted us to un dertake studies on a series of L-en an tiom ers con tain in g
th e pyrrolo[2,3-d]pyrim idin e system . Herein , we report on th e syn th esis of
th e 7-deazapurin e β-L-2′-deoxyribon ucleosides 1–4 an d β-L-ribon ucleosides
such as 5–7 (Sch em e 1). Th eir ph ysical properties are discussed an d data on
th eir an tiviral activity are reported.
SCHEME 1
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958
Seela, Peng:
RESULTS AND DISCUSSION
Con siderin g iden tical ch em ical properties of L- an d D-n ucleosides an d th eir
precursors in a n on ch iral en viron m en t, th e protocols developed for th e
ch em ical syn th esis of 7-deazapurin e D-n ucleoside can be em ployed for th e
preparation of th e L-en an tiom ers16. In stead of th e 3,5-di-O-(4-m eth yl-
ben zoyl)-2-deoxy-α-D-erythro-pentofuranosyl chloride and 1-O-acetyl-2,3,5-tri-
O-benzoyl-D-ribofuran ose, th e correspon din g L-en an tiom ers are used as
sugar com pon en ts. Th e 3,5-di-O-(4-m eth ylben zoyl)-2-deoxy-α-L-erythro-
pen tofuran osyl ch loride (8), wh ich was already described in 1964 1a, was
prepared accordin g to th e procedure for th e correspon din g D-h alogen ose17a
an d was em ployed in th e syn th esis of th e 7-deazapurin e β-L-2′-deoxy-
ribon ucleosides. Th e 1-O-acetyl-2,3,5-tri-O-ben zoyl-L-ribofuran ose (16)1b,17b
was used for β-L-ribon ucleoside syn th esis.
Synthesis of 7-Deazapurine β-L-2′-Deoxyribonucleosides
via the Stereoselective Nucleobase Anion Glycosylation
18,19
Th e glycosylation of th e 2-am in o-4-ch loro-7-deazapurin es 9a,9b
with
th e α-L-2-deoxyribofuran osyl h alide 8 was perform ed in MeCN in th e pres-
en ce of powdered KOH usin g TDA-1 (tris[2-(2-m eth oxyeth oxy)eth yl]am in e)
as ph ase-tran sfer catalyst (n ucleobase-an ion glycosylation con dition s20
)
(Sch em e 2). Th is reaction furn ish ed th e β-L-2′-deoxyribon ucleosides 10a
SCHEME 2
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
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(85%) or 10b (66%), exclusively. Com poun ds 10a, 10b were deprotected in
saturated m eth an olic am m on ia at room tem perature affordin g th e β-L-n u-
cleosides 11a, 11b. Th e protected n ucleosides 10a, 10b were also em ployed
in various n ucleoph ilic displacem en t reaction s. Th e n ucleosides were
treated with 0.5 M NaOMe/MeOH un der reflux to give th e 4-m eth oxy deriv-
atives 12a, 12b, wh ich were con verted to th e 2′-deoxyguan osin e an alogs
2a, 2b (2 M NaOH). Rem oval of th e toluoyl groups an d subsequen t displace-
m en t of th e 6-ch loro substituen ts of 10a,10b were perform ed usin g 25%
aq. NH3 in a sealed steel vessel, furn ish in g th e 2,6-diam in o n ucleosides 3a,
3b. Selective deam in ation of 3a, 3b with sodium n itrite in AcOH/H2O
yielded th e 7-deazaisoguan in e n ucleosides 4a, 4b in 60–70% yield. Th e
6-th io com poun d 2e was obtain ed from 11a reactin g with th iourea in eth a-
n ol un der reflux (Sch em e 3).
SCHEME 3
Sim ilarly, th e glycosylation of 13a, 13d with h alogen ose 8 (MeCN/KOH/
TDA-1) afforded th e toluoyl-protected β-L-2′-deoxyribon ucleosides 14a, 14d
wh ich were n ot purified (Sch em e 4). Th e β-L-2′-deoxytubercidin (1a) was
obtain ed from 14a by n ucleoph ilic displacem en t of th e ch loro substituen t
SCHEME 4
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960
Seela, Peng:
(aq. NH3/dioxan e, 80 °C). Com poun d 14d was treated with m eth an olic am -
m on ia to yield 15d , wh ich was con verted to β-L-2′-deoxy-7-iodotubercidin
(1d ) in aq. NH3/dioxan e (120 °C).
Synthesis of 7-Deazapurine β-L-Ribonucleosides by the One-Pot
Silyl–Hilbert–Johnson Reaction under Vorbrüggen Conditions
Recen tly, we h ave reported on an efficien t m eth od for th e syn th esis of
7-substituted 7-deazapurin e ribon ucleosides usin g com m ercially available
1-O-acetyl-2,3,5-tri-O-ben zoyl-D-ribofuran ose as a sugar m oiety18. Con -
siderin g th e sim ilarity of th e L-ribon ucleosides an d D-ribon ucleosides, we
n ow applied th is protocol for th e preparation of 7-substituted 7-deaza-
purin e β-L-ribon ucleosides. In th is m eth od, th e glycosylation reaction is
perform ed in MeCN usin g N,O-bis(trim eth ylsilyl)acetam ide (BSA) as a silyl-
atin g reagen t an d trim eth ylsilyl trifluorom eth an esulfon ate (TMSOTf) as
catalyst. Th e glycosylation of th e 2-pivalam ido 7-deazapurin e derivatives
21
17b–17d
with 1-O-acetyl-2,3,5-tri-O-ben zoyl-L-ribofuran ose (16) (BSA/
TMSOTf/MeCN) afforded th e β-L-ribon ucleosides 18b–18d in 66–73% yield
(Sch em e 5).
SCHEME 5
Th e n ucleosides 18b–18d were con verted to th e 2,6-diam in o n ucleosides
6b–6d in aq. NH3 at 120 °C in an autoclave (Sch em e 6). Th e 4-m eth oxy com -
poun ds 19b –19d were obtain ed by treatm en t of 18b –18d with 0.5
M
NaOMe un der reflux con dition s an d th e 7-deazaguan osin e derivatives
5b–5d were prepared from 19b–19d by m eth yl eth er cleavage (2 M NaOH).
Deam in ation of com poun ds 19c, 19d with NaNO2/AcOH yielded th e 2-oxo
n ucleosides 20c, 20d ; th e m eth oxy group was displaced by a h ydroxy fun c-
tion upon treatm en t with 2 M NaOH un der reflux con dition s for 36 h yield-
in g th e 7-substituted 7-deazaxan th osin es 7c, 7d .
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
961
SCHEME 6
Physical Properties and Characterization
1
All com poun ds were ch aracterized by H NMR (Experim en tal) an d 13C NMR
spectra (Table I) as well as by elem en tal an alyses (Experim en tal). Th e as-
sign m en ts of th e 13C NMR ch em ical sh ifts are m ade accordin g to th e corre-
spon din g D-n ucleosides18,21–23. Th e structure of 2′-deoxy-7-iodotubercidin
(1d ) was con firm ed by sin gle-crystal X-ray an alysis (Fig. 1) (data will be
publish ed elsewh ere).
Th e β-L-con figuration was deduced from th e CD spectra m easured for
both th e 7-deazapurin e L-n ucleosides an d th e correspon din g D-en an tio-
m ers. Selected spectra are sh own in Fig. 2. By com parin g th e CD spectra of
th e β-L- an d β-D-n ucleosides (Fig. 2a–2d), m irror im ages of th e ellipticities
con firm ed th e en an tiom eric ch aracter. Th e β-L-n ucleosides sh ow a positive
lobe wh ile a n egative lobe is form ed by th e β-D-en an tiom ers. All 7-deaza-
purin e n ucleosides sh ow rath er low ellipticity values com pared to th e par-
en t purin e n ucleosides, wh ich explain s th e m oderate quality of th e spectra.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

962
Seela, Peng:
FIG. 1
Perspective views of com poun d 1d . Displacem en t ellipsoids are sh own at th e 50% probability
level an d H atom s are sh own as sph eres of arbitrary size
FIG. 2
Th e CD spectra m easured in MeOH at con cen tration s (in m ol/l): 4.5 × 10–5 (a), 4.1 × 10–5 (b),
9.8 × 10–5 (c), 9.5 × 10–5 (d)
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
963
TABLE I
13C NMR ch em ical sh ifts (δ) of 7-deazapurin e L-n ucleosidesa
Com pd C(2)d C(4)d C(4a) C(5)
C(6)
C(8)
C(7a)d C(1′) C(2′) C(3′) C(4′) C(5′)
C(4)
b,c
C(2)
C(6)
C(5)
C(7)
β-L-2′-Deoxyribon ucleosides
e
e
e
e
e
e
e
e
e
1a
151.9 157.8 103.2 100.0 122.0 150.0 83.6
151.7 157.0 103.1 52.1 126.9 149.6 83.0
71.5
70.9
70.9
70.9
70.9
71.1
70.9
71.2
71.8
75.2
75.3
70.9
70.8
71.0
71.0
70.7
87.6
87.4
86.9
87.1
87.1
87.1
87.2
86.9
87.8
82.0
82.5
87.1
87.3
86.9
87.1
87.7
62.5
61.9
62.0
61.9
61.9
62.1
61.9
62.3
62.8
64.2
64.2
61.9
61.7
62.0
61.9
61.5
1d
2a
158.6 152.6
157.5 153.1
99.9 102.2 116.7 150.5 82.1
97.0 106.3 114.0 149.8 82.1
2b
2e
152.2 175.7 104.3 113.1 120.1 147.0 82.2
f
3a
153.1 156.1
152.5 156.3
159.9 157.9
161.2 158.0
92.4 100.7 119.0
90.2 103.7 116.3
83.3
82.6
f
3b
4a
96.3 100.0 117.4 152.5 82.6
94.2 104.1 115.4 152.7 82.8
4b
10a
10b
11a
11b
12a
12b
15d
158.6 153.6 11.3
158.9 152.9 108.0 106.4 119.9 152.8 84.1
159.3 153.7 99.8 108.8 123.0 151.1 82.3
159.6 152.8 104.9 103.0 120.2 150.5 82.2
101.3 122.5 152.8 84.1
37.3
37.8
e
e
e
e
e
162.8 159.4
162.8 159.9
97.1
99.0 119.4 154.2 82.2
95.0 103.2 116.4 153.2 82.1
150.7 151.0 116.5
53.4 133.4 150.4 83.4
β-L-Ribon ucleosides
5b
153.0 157.5
152.9 157.7
152.5 158.1
160.3 157.2
160.2 157.3
159.7 157.5
151.1 158.7
150.3 158.9
97.1 106.3 114.3 150.4 85.7
73.6
73.6
73.8
73.4
73.4
73.3
74.0
74.1
71.3
71.6
71.2
73.5
73.5
73.5
73.8
73.8
70.5
70.5
70.4
70.6
70.6
70.6
70.6
70.6
74.0
74.2
73.9
70.5
70.5
70.5
70.5
70.5
84.8
84.8
84.6
84.7
84.7
84.7
89.1
89.1
79.3
79.6
79.1
84.8
84.8
84.8
85.2
85.1
61.5
61.5
61.5
61.7
61.7
61.7
61.3
61.3
63.7
63.9
63.7
61.6
61.6
61.6
61.4
61.4
5c
98.1
99.9
90.4 116.8 150.8 85.7
54.5 121.9 151.0 85.9
5d
6b
93.5 103.3 115.1 152.4 85.8
6c
94.5
96.5
97.3
99.1
87.5 117.5 152.7 85.7
52.3 123.0 153.2 85.8
91.1 117.5 140.1 85.7
56.3 122.9 139.0 85.7
6d
7c
7d
18b
18c
18d
19b
19c
19d
20c
20d
152.4 150.7 110.1 103.5 126.0 150.6 87.7
152.4 151.5 111.5
151.8 151.6 113.3
88.2 129.6 151.7 88.8
54.1 128.4 151.3 87.6
159.8 162.7
159.7 162.8
159.4 162.8
160.6 163.9
95.0 103.2 116.6 153.7 85.6
96.3
98.8
98.4
87.2 119.1 154.2 85.7
51.8 124.5 154.8 85.6
f
87.3 120.9
52.0 126.8
86.4
86.4
f
160.3 163.9 100.5
a
b
c
Measured in DMSO-d6. First lin e – system atic n um berin g. Secon d lin e – purin e n um ber-
d
e
f
in g. Ten tative. Superim posed by DMSO. Not detected.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

964
Inhibitory Activity
Seela, Peng:
Th e 7-deazapurin e β-L-n ucleosides described above as well as th eir β-D-iso-
m ers were evaluated in cell culture experim en ts to test th e in h ibition of th e
replication of RNA viruses in cludin g h um an im m un odeficien cy virus-1
(HIV-1), bovin e viral diarrh ea virus (BVDV), yellow fever virus (YFV), den -
gue virus (DENV-2), an d West Nile virus (WNV). A retrovirus, n am ely h u-
m an im m un odeficien cy virus-1 (HIV-1) an d a DNA virus (Hepatitis B virus,
HBV) were used as well. Th e data are sum m arized in Tables II an d III;
sch em es of com poun ds 21–29, see Ch art 1. Th e results sh ow th at m ost of
th ese com poun ds do n ot sh ow sign ifican t an tiviral activity. On ly in th e
case of β-D-2′-deoxytubercidin (21a), selective activity again st HBV was ob-
served (EC50 = 0.5 µM), wh ile th is is n ot th e case of th e correspon din g L-iso-
m er 1a. Its 7-iodo derivative 1d is cytotoxic again st HIV-1 an d HBV as well
as th e 2,6-diam in o-7-deazapurin e D-ribon ucleosides 26c, 26d an d 2-am in o-
6-m eth oxy-7-deazapurin e an alogs 27b–27d (Table II). Com poun ds 26c, 26d
are also toxic again st YFV (Table III).
NH2
NH2
Cl
N
O
N
O
N
R
R
R
R
R
N
N
N
HN
HN
N
N
N
N
N
N
O
H2N
HO
N
O
H2N
HO
H2N
HO
H2N
HO
HO
O
O
O
HO
21a,d
HO
HO
HO OH
HO
23b
24b
25b,c
22a
OMe
OMe
R
OMe
NH2
R
R
N
HN
N
N
N
N
N
N
H2N
HO
N
O
N
H2N
HO
N
H2N
HO
N
HO
O
O
O
O
HO OH
HO OH
HO
HO OH
27b-d
28c,d
29
26c,d
a: R = H; b: R = Cl; c: R = Br; d: R = I
CHART 1
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
965
TABLE II
An tiviral activities of 7-deazapurin e β-L-n ucleosides an d th e correspon din g β-D-n ucleosides
again st HIV-1 an d HBV virusesa
HBV
RI
HBV
Tox
HBV
RI
HBV
Tox
HIV-1
HIV-1
b
c
d
e
b
c
d
e
EC50
CC50
EC50
CC50
EC50
CC50
EC50
CC50
L-1a
D-21a22
>100
>100
16/18
n .d.
>100
>100
>10
0.5
>100
>100
4
D-26c18
D-26d 18 >1.3
D-24b21 >77
>3
3
n .d.
n .d.
>10
>10
n .d.
n .d.
>10
n .d.
n .d.
>10
n .d.
n .d.
>50
>100
n .d.
n .d.
12
1.3
77
L-1d
16/18
3.7
>4
D-21d 23
L-2a
D-22a20
n .d.
n .d.
10
n .d.
n .d.
>100
n .d.
>50
n .d.
n .d.
n .d.
L-12a
D-27b18 >4
D-27c18
D-27d 18 >0.7
D-28c18
D-28d 18 >100
L-15d >5.3
>100
>100
4
>100
>100
>100
>48
>100
>100
>100
48
>1.4
1.4
0.7
>100
>100
5.3
L-3a
n .d.
>10
n .d.
n .d.
n .d.
D-23b21
L-4a
D-25b18
D-25c18
>100
n .d.
n .d.
10
>100
>100
>100
>100
>100
>100
a
b
n .d., n ot yet determ in ed. Com poun d con cen tration (µM) required to ach ieve 50% protec-
tion of CD4+ h um an T-cells con tain in g an in tegrated HTLV-1 gen om e (MT-4 cells) from th e
HIV-1-in duced cytopath ogen icity, as determ in ed by th e MTT m eth od. Com poun d con cen -
c
tration (µM) required to reduce th e viability of m ock-in fected MT-4 cells by 50%, as deter-
d
m in ed by th e MTT m eth od.
Com poun d con cen tration (µM) required to reduce th e
e
in tracellular HBV DNA (HBV RI). Com poun d con cen tration (µM) required to reduce th e vi-
ability of h epatocellular carcin om a (HepG2) cells by 50%, as determ in ed by th e MTT
m eth od.
Conclusion
Th e stereoselective syn th esis of a n um ber of 7-deazapurin e β-L-2′-deoxy-
ribon ucleosides an d β-L-ribon ucleosides was accom plish ed usin g n ucleo-
base an ion glycosylation or Silyl–Hilbert–Joh n son reaction perform ed
un der Vorbrüggen con dition s (TMSOTf/BSA/MeCN). Th e 3,5-di-O-(4-m eth yl-
ben zoyl)-2-deoxy-α-L-erythro-pen tofuran osyl ch loride (8) an d 1-O-acetyl-
2,3,5-tri-O-ben zoyl-L-ribofuran ose (16) were em ployed for th e glycosylation
reaction . Th e m irror im ages of th e CD spectra of th e β-L- an d β-D-
n ucleosides con firm ed th e en an tiom eric ch aracter. Most of th e 7-deaza-
purin e β-L-n ucleosides do n ot sh ow sign ifican t an tiviral activity; som e of
th em are cytotoxic.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

966
Seela, Peng:
TABLE III
An tiviral activities of 7-deazapurin e β-L-n ucleosides an d th e correspon din g β-D-n ucleosides again st RNA
virusesa
BVDV
YFV
DENV-2
WNV
b
c
d
e
d
e
d
e
EC50
CC50
EC50
CC50
EC50
CC50
EC50
CC50
L-1a
D-21a
L-1d
L-2a
D-22a
L-2b
L-3a
D-23a
L-3b
D-23b
L-4a
L-4b
L-5b
D-25b
L-5c
D-25c
L-5d
L-6c
>100
>100
>100
>100
>100
>100
12/14
>100
>100
n .d.
>100
n .d.
n .d.
>100
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
>1.7
n .d.
>3
>100
>100
>100
>100
>20/12
n .d.
>100
n .d.
n .d.
n .d.
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
>29
>100
>100
>100
>100
>20/12
n .d.
>100
n .d.
n .d.
n .d.
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
>29
>100
>100
36/46
>100
>100
>100
>100
>73
36/46
>100
>100
>100
>100
73
12/14
>100
>100
n .d.
>100
n .d.
n .d.
>100
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
1.7
20/12
n .d.
>100
n .d.
n .d.
n .d.
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
29
20/12
n .d.
>100
n .d.
n .d.
n .d.
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
n .d.
>100
n .d.
>100
n .d.
n .d.
n .d.
n .d.
n .d.
29
>73
>79
73
79
>250f
>100
>100
>100
>100
>100
>100
>100
>80
>250
>100
>100
>100
>100
>100
>100
>100
>80
>100
22
50
>100
>100
>100
>100
26
>100
10
>100
>11
>100
>250
>100
>175
51
D-26c
L-6d
>100
>22
>50
>100
>100
>100
>100
>26
>100
>10
>100
>11
>100
>250f
>100
>175f
>51
n .d.
3
D-26d
L-11b
D-24b
L-12a
D-2920a
L-19b
D-27b
L-19c
D-27c
L-19d
D-27d
L-20c
D-28c
L-20d
D-28d
L-15d
n .d.
>100
>100
>100
n .d.
>100
n .d.
>71
n .d.
>100
>100
>100
n .d.
≥100
n .d.
71
n .d.
>16
n .d.
16
n .d.
n .d.
n .d.
n .d.
>45
n .d.
n .d.
n .d.
n .d.
45
n .d.
n .d.
n .d.
n .d.
>78
n .d.
n .d.
n .d.
n .d.
78
n .d.
n .d.
n .d.
n .d.
>78
n .d.
n .d.
n .d.
n .d.
78
a
b
n .d., n ot yet determ in ed.
Com poun d con cen tration (µM) required to ach ieve 50% protection of
pre-in fected Madin Darby Bovin Kidn ey (MDBK) cells from th e BVDV-in duced cytopath ogen icity, as de-
c
term in ed by th e MTT m eth od. Com poun d con cen tration (µM) required to reduce th e viability of
d
m ock-in fected MDBK cells by 50%, as determ in ed by th e MTT m eth od. Com poun d con cen tration (µM)
required to ach ieve 50% protection of Baby Ham ster Kidn ey (BHK-21) cells from th e YFV, DENV-2 an d
e
WNV-in duced cytopath ogen icity, as determ in ed by th e MTT m eth od. Com poun d con cen tration (µM) re-
f
quired to reduce th e viability of m ock-in fected BHK cells by 50%, as determ in ed by th e MTT m eth od.
Com poun d con cen tration (µM) required to protect 50% of n on -pre-in fected MDBK cells from th e
BVDV-in duced cytopath ogen icity, as determ in ed by th e MTT m eth od.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
967
EXPERIMENTAL
Gen eral
All ch em icals were purch ased from Sigm a–Aldrich (Sigm a–Aldrich Ch em ie Gm bH,
Taufkirch en , Germ an y). 3,5-Di-O-(4-m eth ylben zoyl)-2-deoxy-α-L-erythro-pen tofuran osyl ch lo-
ride (8)1a an d 1-O-acetyl-2,3,5-tri-O-ben zoyl-L-ribofuran ose (16)1b were prepared as described
for th e correspon din g D-isom ers17a,17b. Solven ts were of laboratory grade. Th in -layer ch rom a-
tograph y (TLC): alum in um sh eets, silica gel 60 F254, 0.2 m m layer (VWR In tern ation al,
Darm stadt, Germ an y). Colum n flash ch rom atograph y (FC): silica gel 60 (VWR In tern ation al,
Darm stadt, Germ an y) at 0.4 bar. Sam ple collection with a MultiRac fraction s collector (LKB
In strum en ts Sweden ). UV spectra were recorded on a U-3200 spectroph otom eter (Hitach i,
Japan ), λm ax in n m , ε in dm 3 m ol–1 cm –1. Th e CD spectra were m easured with a Jasco J-600A
spectropolarim eter (Jasco, Japan ) at room tem perature usin g a 1.0 m l water-jacketed cylin dri-
cal cells of 1-cm path len gth . Th e spectra were recorded between 200 n m an d 350 n m in in -
tervals of 0.5 n m . NMR spectra were m easured on an Avan ce DPX 250 or an AMX-500
spectrom eter (Bruker, Rh ein stetten , Germ an y); ch em ical sh ifts (δ) are in ppm down field
from in tern al TMS (1H, 13C). Th e J values are given in Hz. Meltin g poin ts were determ in ed
with a Lin ström apparatus an d are n ot corrected. Elem en tal an alyses were perform ed by th e
Mikroan alytisch es Laboratorium Beller, Göttin gen , Germ an y.
4-Ch loro-7-[2-deoxy-3,5-di-O-(4-m eth ylben zoyl)-β-L-erythro-pen tofuran osyl]-
7H-pyrrolo[2,3-d]pyrim idin -2-am in e (10a)
To a suspen sion of powdered KOH (85%, 1.15 g, 17.42 m m ol) an d TDA-1 (0.2 m l, 0.63 m m ol)
in MeCN (60 m l), 2-am in o-4-ch loro-7H-pyrrolo[2,3-d]pyrim idin e (9a 19; 842 m g, 4.99 m m ol)
was added at room tem perature. After th e m ixture was stirred for 5 m in , 3,5-di-O-ben zoyl-
2-deoxy-α-L-erythro-pen tofuran osyl ch loride (8 1a,17a; 2.53 g, 6.51 m m ol) was in troduced
with in 15 m in , an d th e stirrin g was con tin ued for 30 m in . Th e in soluble m aterial was fil-
tered off, th e precipitate was wash ed with MeCN, an d th e filtrate was evaporated to dryn ess.
Th e residue was dissolved in CH2Cl2, applied on to flash ch rom atograph y (FC) (silica gel,
colum n 6 × 12 cm ), an d th e com poun d was eluted with CH2Cl2. Th e product-con tain in g
fraction s were com bin ed an d evaporated to give a colorless foam (2.21 g, 85%). TLC (silica
gel, CH2Cl2/MeOH, 99:1): RF 0.25. For C27H25ClN4O5 (521.0) calculated: 62.25% C, 4.84% H,
10.75% N; foun d: 62.20% C, 4.91% H, 10.80% N. 1H NMR (250 MHz, CDCl3): 2.42 s, 3 H
(CH3); 2.44 s, 3 H (CH3); 2.64–2.69 m , 1 H (H-2′); 2.85–2.91 m , 1 H (H-2′); 4.57–4.64 m , 2 H
(H-5′); 4.71–4.77 m , 1 H (H-4′); 5.06 s, 2 H (NH2); 5.73–5.76 m , 1 H (H-3′); 6.38 d, 1 H,
J(5,6) = 3.8 (H-5); 6.58 dd, 1 H, J(1′,2′) = 5.8, 8.4 (H-1′); 7.01 d, 1 H, J(5,6) = 3.8 (H-6);
7.24–7.97 m , 8 H (C6H4).
4,5-Dich loro-7-[2-deoxy-3,5-di-O-(4-m eth ylben zoyl)-β-L-erythro-pen tofuran osyl]-
7H-pyrrolo[2,3-d]pyrim idin -2-am in e (10b)
As described for 10a, with 2-am in o-4,5-dich loro-7H-pyrrolo[2,3-d]pyrim idin e (9b18; 1.02 g,
5.02 m m ol), halogenose 8 (2.53 g, 6.51 m m ol), MeCN (60 m l), KOH (85%, 1.15 g, 17.42 m m ol),
an d TDA-1 (0.2 m l, 0.63 m m ol). FC (silica gel, colum n 6 × 12 cm , CH2Cl2) afforded a color-
less foam (1.83 g, 66%). TLC (silica gel, CH2Cl2/MeOH, 99:1): RF 0.28. For C27H24Cl2N4O5
(555.4) calculated: 58.39% C, 4.36% H, 10.09% N; foun d: 58.61% C, 4.35% H, 9.95% N.
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

968
Seela, Peng:
1H NMR (250 MHz, CDCl3): 2.66 s, 3 H (CH3); 2.67 s, 3 H (CH3); 2.88–2.90 m , 1 H (H-2′);
2.99–3.02 m , 1 H (H-2′); 4.77–4.87 m , 2 H (H-5′); 4.88–4.96 m , 1 H (H-4′); 5.33 s, 2 H (NH2);
5.93–5.95 m , 1 H (H-3′); 6.79 t, 1 H, J(1′,2′) = 6.4 (H-1′); 7.48–7.52 m , 5 H (H-6, arom H);
8.14–8.21 m , 4 H (arom H).
4-Ch loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -2-am in e (11a)
A solution of com poun d 10a (782 m g, 1.50 m m ol) in NH3/MeOH (saturated at 0 °C, 50 m l)
was stirred at room tem perature overn igh t. Th e clear solution was evaporated, an d th e resi-
due was applied on to FC (silica gel, colum n 4 × 16 cm , CH2Cl2/MeOH, 95:5). After evapora-
tion , th e m ain zon e yielded a colorless solid (350 m g, 82%). TLC (silica gel, CH2Cl2/MeOH,
9:1): RF 0.39. For C11H13ClN4O3 (284.7) calculated: 46.41% C, 4.60% H, 19.68% N; foun d:
46.30% C, 4.53% H, 19.50% N. UV (MeOH): 234 (28700), 258 (4300), 316 (sh 5700). 1H NMR
(250 MHz, DMSO-d6): 2.10–2.17 m , 1 H (H-2′); 2.35–2.46 m , 1 H (H-2′); 3.46–3.56 m , 2 H
(H-5′); 3.74–3.79 m , 1 H (H-4′); 4.30–4.33 m , 1 H (H-3′); 4.90 t, 1 H, J = 5.1 (OH-5′); 5.25 d,
1 H, J = 3.5 (OH-3′); 6.35 d, 1 H, J(5,6) = 3.6 (H-5); 6.42 t, 1 H, J(1′,2′) = 6.9 (H-1′); 6.69 br s,
2 H (NH2); 7.37 d, 1 H, J(5,6) = 3.6 (H-6).
4,5-Dich loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -
2-am in e (11b)
As described for 11a, with com poun d 10b (1.11 g, 2.00 m m ol) an d NH3/MeOH (saturated at
0 °C, 60 m l). FC resulted in a colorless solid (574 m g, 90%). TLC (silica gel, CH2Cl2/MeOH,
9:1): RF 0.39. For C11H12Cl2N4O3 (319.1) calculated: 41.40% C, 3.79% H, 17.56% N; foun d:
41.49% C, 3.74% H, 17.40% N. UV (MeOH): 241 (29700), 264 (4000), 324 (5400). 1H NMR
(250 MHz, DMSO-d6): 2.12–2.16 m , 1 H (H-2′); 2.36–2.39 m , 1 H (H-2′); 3.49–3.54 m , 2 H
(H-5′); 3.78–3.81 m , 1 H (H-4′); 4.31–4.33 m , 1 H (H-3′); 4.96 t, 1 H, J = 5.6 (OH-5′); 5.28 d,
1 H, J = 3.6 (OH-3′); 6.31 dd, 1 H, J(1′,2′) = 6.0, 8.1 (H-1′); 6.94 br s, 2 H (NH2); 7.55 s, 1 H
(H-6).
7-(2-Deoxy-β-L-erythro-pen tofuran osyl)-4-m eth oxy-7H-pyrrolo[2,3-d]pyrim idin -2-am in e (12a)
A solution of 10a (1.04 g, 2.00 m m ol) in 0.5 M NaOMe/MeOH (60 m l) was stirred un der re-
flux for 3 h . Th e m ixture was n eutralized with AcOH an d evaporated. Th e residue was ap-
plied on to FC (silica gel, CH2Cl2/MeOH, 95:5→9:1). After evaporation , th e m ain zon e gave a
colorless solid (400 m g, 71%). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.43. For C12H16N4O4
(280.3) calculated: 51.42% C, 5.75% H, 19.99% N; foun d: 51.20% C, 5.99% H, 19.96% N.
UV (MeOH): 224 (23600), 261 (9300), 287 (7300). 1H NMR (250 MHz, DMSO-d6): 2.06–2.10 m ,
1 H (H-2′); 2.34–2.40 m , 1 H (H-2′); 3.45–3.50 m , 1 H (H-5′); 3.73–3.76 m , 1 H (H-4′); 3.91 s,
3 H (OMe); 4.28–4.32 m , 1 H (H-3′); 4.94 br s, 1 H (OH-5′); 5.22 br s, 1 H (OH-3′); 6.22–6.26 m ,
3 H (NH2, H-1′); 6.41 d, 1 H, J(5,6) = 3.8 (H-5); 7.10 d, 1 H, J(5,6) = 3.8 (H-6).
5-Ch loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-4-m eth oxy-7H-pyrrolo[2,3-d]pyrim idin -
2-am in e (12b)
As described for 12a, with com poun d 10b (833 m g, 1.50 m m ol) an d 0.5 M NaOMe/MeOH
(40 m l). FC resulted in a colorless solid (430 m g, 91%). TLC (silica gel, CH2Cl2/MeOH, 9:1):
RF 0.45. For C12H15ClN4O4 (314.7) calculated: 45.80% C, 4.80% H, 17.80% N; foun d: 45.92% C,
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
969
4.87% H, 18.00% N. UV (MeOH): 230 (27200), 265 (8300), 289 (6700). 1H NMR (250 MHz,
DMSO-d6): 2.06–2.11 m , 1 H (H-2′); 2.29–2.40 m , 1 H (H-2′); 3.46–3.50 m , 1 H (H-5′);
3.74–3.76 m , 1 H (H-4′); 3.92 s, 3 H (OMe); 4.27–4.31 m , 1 H (H-3′); 4.95 t, 1 H, J = 5.2
(OH-5′); 5.25 d, 1 H, J = 2.7 (OH-3′); 6.36–6.45 m , 3 H (NH2, H-1′); 7.23 s, 1 H (H-6).
2-Am in o-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -4(3H)-on e (2a)
A solution of com poun d 12a (140 m g, 0.50 m m ol) in 2 M NaOH (40 m l) was h eated un der
reflux for 3 h . After coolin g an d n eutralization with 2 M HCl, th e crude product of 2a was
ch rom atograph ed on
a Serdolit AD-4 colum n (3 × 12 cm , resin 0.1–0.2 m m ; Serva,
Germ an y). Th e colum n was wash ed with H2O (150 m l), an d th e product was eluted with
H2O/i-PrOH (9:1, 200 m l). Th e product con tain in g fraction s were collected an d th e solven t
was rem oved to ca. 30 m l. Com poun d 2a crystallized from H2O. Colorless crystals (108 m g,
81%), m .p. 247–248 °C (dec. H2O). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.22. For
C
11H14N4O4 (266.3) calculated: 49.62% C, 5.30% H, 21.04% N; foun d: 49.52% C, 5.46% H,
20.82% N. UV (MeOH): 218 (20500), 260 (12400), 285 (6500). 1H NMR (250 MHz,
DMSO-d6): 2.05–2.10 m , 1 H (H-2′); 2.30–2.36 m , 1 H (H-2′); 3.45–3.50 m , 1 H (H-5′);
3.73–3.76 m , 1 H (H-4′); 4.26–4.30 m , 1 H (H-3′); 4.90 br s, 1 H (OH-5′); 5.21 br s, 1 H
(OH-3′); 6.27–6.30 m , 4 H (H-5, NH2, H-1′); 6.91 d, 1 H, J(5,6) = 3.8 (H-6); 10.44 s, 1 H (NH).
2-Am in o-5-ch loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -
4(3H)-on e (2b)
Com poun d 2b was prepared from 12b (315 m g, 1.00 m m ol) an d 2 M NaOH (60 m l) as de-
scribed for 2a. Colorless n eedles (262 m g, 87%), m .p. 206–207 °C (dec. H2O). TLC (silica gel,
CH2Cl2/MeOH, 9:1): RF 0.24. For C11H13ClN4O4 (300.7) calculated: 43.94% C, 4.36% H,
18.63% N; foun d: 43.80% C, 4.40% H, 18.52% N. UV (MeOH): 222 (20600), 265 (12100),
287 (7100). 1H NMR (250 MHz, DMSO-d6): 2.05–2.09 m , 1 H (H-2′); 2.27–2.32 m , 1 H (H-2′);
3.45–3.52 m , 1 H (H-5′); 3.73–3.75 m , 1 H (H-4′); 4.26–4.29 m , 1 H (H-3′); 4.94 t, 1 H, J =
5.0 (OH-5′), 5.21 d, 1 H, J = 3.3 (OH-3′); 6.29 dd, 1 H, J(1′,2′) = 6.1, 7.7 (H-1′); 6.41 s, 2 H
(NH2); 7.06 s, 1 H (H-6), 10.54 s, 1 H (NH).
2-Am in o-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin e-
4(3H)-th ion e (2e)
A solution of 11a (200 m g, 0.70 m m ol) an d th iourea (160 m g, 2.10 m m ol) in eth an ol
(10.0 m l) was stirred un der reflux for 30 m in . Th e solven t was evaporated an d th e residue
was applied on to FC (silica gel, CH2Cl2/MeOH, 95:5→9:1). Evaporation of th e m ain zon e
gave crude 2e as a colorless solid (168 m g, 85%). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.5.
For C11H14N4O3S (282.3) calculated: 46.80% C, 5.00% H, 19.85% N, 11.36% S; foun d:
46.67% C, 4.69% H, 19.68% N, 11.30% S. UV (MeOH): 236 (20500), 269 (10600), 338
(13700). 1H NMR (250 MHz, DMSO-d6): 2.10–2.13 m , 1 H (H-2′); 2.31–2.36 m , 1 H (H-2′);
3.47–3.55 m , 1 H (H-5′); 3.77–3.78 m , 1 H (H-4′); 4.30–4.31 m , 1 H (H-3′); 4.88 t, 1 H, J =
5.4 (OH-5′); 5.22 d, 1 H, J = 3.7 (OH-3′); 6.30 dd, 1 H, J(1′,2′) = 6.1, 7.9 (H-1′); 6.41 d, 1 H,
J(5,6) = 3.6 (H-5); 6.61 br s, 2 H (NH2); 7.14 d, 1 H, J(5,6) = 3.6 (H-6); 10.44 s, 1 H (NH).
Collect. Czech. Chem. Commun. 2006, Vol. 71, No. 7, pp. 956–977

970
Seela, Peng:
7-(2-Deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin e-2,4-diam in e (3a)
A suspen sion of com poun d 10a (782 m g, 1.50 m m ol) in dioxan e (20 m l) an d 25% con cen -
trated aq. NH3 (60 m l) was in troduced in an autoclave an d stirred at 120 °C for 24 h . Th e
clear solution was evaporated, an d th e residue was applied on to FC (silica gel, colum n 4 ×
12 cm , CH2Cl2/MeOH, 95:5→9:1). After evaporation , th e m ain zon e was evaporated yieldin g
crude 3a, wh ich was crystallized from MeOH, givin g colorless crystals (358 m g, 90%), m .p.
213–215 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.31. For C11H15N5O3 (265.3) cal-
culated: 49.81% C, 5.70% H, 26.40% N; foun d: 49.62% C, 5.62% H, 26.12% N. UV (MeOH):
223 (27500), 265 (10500), 287 (8400). 1H NMR (250 MHz, DMSO-d6): 2.01–2.08 m , 1 H
(H-2′); 2.34–2.43 m , 1 H (H-2′); 3.47–3.52 m , 2 H (H-5′); 3.74–3.79 m , 1 H (H-4′); 4.28–4.30 m ,
1 H (H-3′); 5.14–5.18 m , 2 H (OH-5′, OH-3′); 5.51 br s, 2 H (NH2); 6.29–6.39 m , 2 H (H-1′,
H-5); 5.54 br s, 2 H (NH2); 6.89 d, 1 H, J(5,6) = 3.7 (H-6).
5-Chloro-7-(2-deoxy-β-D-erythro-pentofuranosyl)-7H-pyrrolo[2,3-d]pyrim idine-2,4-diam ine (3b)
As described for 3a, com poun d 3b was prepared from 10b (833 m g, 1.50 m m ol), 25% con -
cen trated aq. NH3 (60 m l), an d dioxan e (20 m l). Colorless n eedles (360 m g, 80%), m .p.
203–204 °C (dec. H2O). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.33. For C11H14ClN5O3
(299.7) calculated: 44.08% C, 4.71% H, 23.37% N; foun d: 44.15% C, 4.81% H, 23.31% N.
UV (MeOH): 229 (28100), 269 (9600), 288 (7400). 1H NMR (DMSO-d6): 2.00–2.07 m , 1 H
(H-2′); 2.27–2.38 m , 1 H (H-2′); 3.47–3.49 m , 2 H (H-5′); 3.74–3.78 m , 1 H (H-4′); 4.26–4.28 m ,
1 H (H-3′); 5.01 t, 1 H, J = 5.1 (OH-5′), 5.22 d, 1 H, J = 3.5 (OH-3′); 5.84 br s, 2 H (NH2);
6.31–6.37 m , 3 H (H-1′, NH2); 7.09 s, 1 H (H-6).
4-Am in o-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -2(3H)-on e (4a)
To a solution of com poun d 3a (265 m g, 1.00 m m ol) in AcOH/H2O (1:5 v/v; 40.0 m l), a solu-
tion of NaNO2 (250 m g, 3.62 m m ol) in H2O (8.0 m l) was added dropwise at room tem pera-
ture un der stirrin g. Th e stirrin g was con tin ued for 30 m in , an d th e pH of th e dark solution
was adjusted to pH 6.0 (25% aq. NH3). Th e solution was applied on to a Serdolit AD-4 colum n
(4 × 20 cm , resin 0.1–0.2 m m ; Serva, Germ an y). Th e colum n was wash ed with H2O (200 m l),
an d th e product was eluted with H2O/i-PrOH (95:5, 500 m l). Com poun d 4a crystallized
from H2O as yellowish n eedles (186 m g, 70%), m .p. 231–233 °C (dec.). TLC (silica gel,
CH2Cl2/MeOH, 5:1): RF 0.28. For C11H14N4O4 (266.3) calculated: 49.62% C, 5.30% H,
21.04% N; foun d: 49.75% C, 5.23% H, 21.09% N. UV (MeOH): 227 (28700), 257 (7600), 305
(7400). 1H NMR (250 MHz, DMSO-d6): 2.02–2.09 m , 1 H (H-2′); 2.30–2.41 m , 1 H (H-2′);
3.48–3.53 m , 2 H (H-5′); 3.75–3.79 m , 1 H (H-4′); 4.26–4.29 m , 1 H (H-3′); 5.20–5.22 m , 2 H
(OH-5′, OH-3′); 6.21 dd, 1 H, J(1′,2′) = 6.5, 7.5 (H-1′); 6.41 d, 1 H, J(5,6) = 3.5 (H-5); 6.90 d,
1 H, J(5,6) = 3.5 (H-6); 7.61 br s, 2 H (NH2); 10.97 br s, 1 H (NH).
4-Am in o-5-ch loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -
2(3H)-on e (4b)
As described for 4a, with 3b (300 m g, 1.00 m m ol), AcOH/H2O (1:5 v/v; 40 m l), an d a solu-
tion of NaNO2 (250 m g, 3.62 m m ol) in H2O (8.0 m l). Colorless n eedles from H2O (180 m g,
60%), m .p. 223–234 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.29. For
C
11H13ClN4O4 (300.7) calculated: 43.94% C, 4.36% H, 18.63% N; foun d: 43.75% C, 4.23% H,
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
971
18.39% N. UV (MeOH): 231 (27600); 265 (6100); 311 (5600). 1H NMR (250 MHz, DMSO-d6):
2.06–2.08 m , 1 H (H-2′); 2.28–2.33 m , 1 H (H-2′); 3.48–3.55 m , 2 H (H-5′); 3.77–3.78 m , 1 H
(H-4′); 4.26–4.27 m , 1 H (H-3′); 5.10 br s, 1 H (OH-5′); 5.25 d, 1 H, J = 3.0 (OH-3′); 6.26 t,
1 H, J(1′,2′) = 5.9 (H-1′); 7.15 br s, 3 H (H-6, NH2); 10.80 br s, 1 H (NH).
7-(2-Deoxy-β-L-erythro-pen tofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -4-am in e (1a)
To a solution of 4-ch loro-7H-pyrrolo[2.3-d]pyrim idin e (13a 25; 671 m g, 4.37 m m ol) in MeCN
(60 m l), powdered KOH (85%, 0.5 g, 7.57 m m ol) an d TDA-1 (0.075 m l, 0.24 m m ol) were
added at room tem perature. After stirrin g for 10 m in , h alogen ose 8 (1.7 g, 4.37 m m ol) was
added an d th e stirrin g was con tin ued for an oth er 10 m in . In soluble m aterial was filtered off
an d wash ed several tim es with h ot aceton e. Th e com bin ed filtrates were evaporated to dry-
n ess. Th e residue was applied on to FC (silica gel, colum n 5 × 15 cm , elution with petroleum
eth er/EtOAc, 4:1). Th e fraction s con tain in g product were evaporated to give 4-ch loro-
7-[2-deoxy-3,5-di-O-(4-m eth ylben zoyl)-β-L-erythro-pen tofuran osyl]-7H-pyrrolo[2,3-d]pyrim i-
din e (14a ) as a colorless solid (1.5 g, 68%). A suspen sion of com poun d 14a (1.4 g,
2.77 m m ol) in a m ixture of 25% aq. NH3/dioxan e (1:1, 160 m l) was stirred at 85 °C for 72 h
in an autoclave. Th e clear solution was evaporated an d th e residue was applied on to FC (silica
gel, colum n 5 × 20 cm , CH2Cl2/MeOH, 9:1). Com poun d 1a was obtain ed as colorless solid
(560 m g, 81%). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.16. For C11H14N4O3 (250.3) calcu-
lated: 52.79% C, 5.64% H, 22.39% N; foun d: 52.61% C, 5.62% H, 22.24% N. UV (MeOH):
271 (11500). 1H NMR (250 MHz, DMSO-d6): 2.09–2.18 m , 1 H (H-2’); 2.45–2.54 m , 1 H
(H-2’); 3.49–3.56 m , 2 H (H-5’); 3.81–3.82 m , 1 H (H-4’); 4.30–4.33 m , 1 H (H-3’); 5.17 t, 1 H,
J = 5.5 (OH-5’); 5.25 d, 1 H, J = 3.9 (OH-3’); 6.48 dd, 2 H, J(1’,2’) = 5.9, 8.2 (H-1’); 6.57 d, 1 H,
J(5,6) = 3.6 (H-5); 7.04 br s, 2 H (NH2); 7.34 d, 1 H, J(5,6) = 3.6 (H-6); 8.04 s, 1 H (H-2).
4-Ch loro-7-(2-deoxy-β-L-erythro-pen tofuran osyl)-5-iodo-7H-pyrrolo-[2,3-d]pyrim idin e (15d )
To a solution of 4-ch loro-5-iodo-7H-pyrrolo[2.3-d]pyrim idin e (13d 24; 1.0 g, 3.58 m m ol) in
MeCN (60 m l), powdered KOH (85%, 0.5 g, 7.57 m m ol) an d TDA-1 (0.075 m l, 0.24 m m ol)
were added at room tem perature. After stirrin g for 10 m in , h alogen ose 8 (1.7 g, 4.37 m m ol)
was in troduced an d th e stirrin g was con tin ued for an oth er 10 m in . In soluble m aterial was
filtered off an d wash ed several tim es with h ot aceton e. Th e com bin ed filtrates were evapo-
rated to dryn ess. Th e residue was applied on to FC (silica gel, colum n 5 × 15 cm , elution
with petroleum eth er/EtOAc, 4:1). Th e com bin ed fraction s con tain in g th e product were
evaporated to yield 4-ch loro-7-[2-deoxy-3,5-di-O-(4-m eth ylben zoyl)-β-L-erythro-pen tofuran osyl]-
5-iodo-7H-pyrrolo[2,3-d]pyrim idin e (14d ) as a colorless solid (2.02 g, 89%). A solution of
com poun d 14d (1.8 g, 2.85 m m ol) in NH3/MeOH (saturated at 0 °C, 145 m l) was stirred at
room tem perature for 24 h an d th e solven t was evaporated. FC (silica gel, colum n 4 × 16 cm ,
CH2Cl2/MeOH, 9:1) yielded com poun d 15d as colorless solid (0.45 g, 40%). TLC (silica gel,
CH2Cl2/MeOH, 9:1): RF 0.45. For C11H11ClIN3O3 (395.6) calculated: 33.40% C, 2.80% H,
10.62% N; foun d: 33.41% C, 2.72% H, 10.52% N. UV (MeOH): 234 (27100), 269 (3600), 305
(3400). 1H NMR (250 MHz, DMSO-d6): 2.23–2.29 m , 1 H (H-2′); 2.49–2.57 m , 1 H (H-2′);
3.50–3.62 m , 2 H (H-5′); 3.84–3.85 m , 1 H (H-4′); 4.36–4.37 m , 1 H (H-3′); 5.00 t, 1 H, J =
4.9 (OH-5′); 5.32 d, 1 H, J = 3.5 (OH-3′); 6.62 t, 1 H, J(1′,2′) = 6.8 (H-1′); 8.20 s, 1 H (H-6);
8.65 s, 1 H (H-2).
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972
Seela, Peng:
7-(2-Deoxy-β-L-erythro-pen tofuran osyl)-5-iodo-7H-pyrrolo[2,3-d]pyrim idin -4-am in e (1d )
A suspen sion of com poun d 15d (580 m g, 1.47 m m ol) in a m ixture of 25% aq. NH3/dioxan e
(1:1, 120 m l) was stirred at 110 °C for 17 h in an autoclave. Th e clear solution was evapo-
rated, th e residue was applied on to FC (silica gel, colum n 4 × 12 cm , CH2Cl2/MeOH, 9:1).
Com p ou n d 1d was obtain ed as colorless solid (480 m g, 87%). TLC (silica gel,
CH2Cl2/MeOH, 9:1): RF 0.32. For C11H13IN4O3 (376.2) calculated: 35.12% C, 3.48% H,
14.89% N; fou n d : 34.82% C, 3.35% H, 14.72% N. UV (MeOH): 283 (8500). 1H NMR
(250 MHz, DMSO-d6): 2.11–2.18 m , 1 H (H-2′); 2.39–2.50 m , 1 H (H-2′); 3.50–3.59 m, 2 H
(H-5′); 3.80–3.829 m, 1 H (H-4′); 4.31–4.33 m, 1 H (H-3′); 5.07 br s, 1 H (OH-5′), 5.30 br s, 1 H
(OH-3′); 6.47 t, 1 H, J(1′,2′) = 6.9 (H-1′); 6.72 br s, 2 H (NH2); 7.66 s, 1 H (H-6); 8.10 s, 1 H (H-2).
4,5-Dich loro-2-pivalam ido-7-(2,3,5-tri-O-ben zoyl-β-L-ribofuran osyl)-7H-pyrrolo-
[2,3-d]pyrim idin e (18b). Gen eral Procedure for th e Preparation of 18b–18d
21
To a stirred suspen sion of 4,5-dich loro-2-pivalam ido-7H-pyrrolo[2,3-d] pyrim idin e (17b
;
574 m g, 2.00 m m ol) in an h ydrous MeCN (14 m l), N,O-bis(trim eth ylsilyl)acetam ide (BSA,
97%, 0.6 m l, 2.41 m m ol) was added at room tem perature un der stirrin g. After 5 m in ,
trim eth ylsilyl trifluorom eth an esulfon ate (TMSOTf: 0.50 m l, 2.59 m m ol) was added an d th e
tem perature was raised to 50 °C (oil bath ). Th en 1-O-acetyl-2,3,5-tri-O-ben zoyl-L-ribo-
furan ose (16 1b,17b; 2.02 g, 4.00 m m ol) was in troduced in th ree portion s with in 24 h (on e
every 8 h ). Th e reaction was cooled to room tem perature an d diluted with CH2Cl2 (50 m l).
Th e organ ic ph ase was wash ed with saturated aq. NaHCO3 an d brin e, dried over an h ydrous
Na2SO4, evaporated un der reduced pressure to give a syrup, wh ich was applied on to FC
(silica gel, colum n 4 × 12 cm , CH2Cl2). Th e m ain zon e afforded com poun d 18b as a yellow-
ish foam (0.97 g, 66%). TLC (silica gel, CH2Cl2/MeOH, 99:1): RF 0.30. For C37H32Cl2N4O8
(731.6) calculated: 60.74% C, 4.41% H, 7.66% N; found: 60.72% C, 4.30% H, 7.65% N. 1H NMR
(250 MHz, DMSO-d6): 1.19 s, 9 H (3 Me); 4.61–4.86 m , 3 H (H-4′, H-5′); 6.35–6.38, 6.41–6.44
2 m , 2 H (H-3′, H-2′); 6.52 d, 1 H, J(1′,2′) = 3.7 (H-1′); 7.42–7.49 m , 6 H (arom H); 7.63–7.65 m ,
3 H (arom H); 7.88–7.96 m , 6 H (arom H); 8.03 s, 1 H (H-6); 10.39 s, 1 H (NH).
5-Bromo-4-chloro-2-pivalamido-7-(2,3,5-tri-O-benzoyl-β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyri-
midine (18c). As described for 18b, com poun d 18c was prepared from 5-brom o-4-ch loro-
2-pivalam ido-7H-pyrrolo[2,3-d]pyrim idin e (17c 21; 663 m g, 2.00 m m ol), th e sugar 16 (2.02 g,
4.00 m m ol), MeCN (14 m l), BSA (97%, 0.6 m l, 2.41 m m ol), an d TMSOTf (0.50 m l, 2.59 m m ol).
FC resulted in a yellowish foam (1.06 g, 68%). TLC (silica gel, CH2Cl2/MeOH, 99:1): RF 0.30.
For C37H32ClBrN4O8 (776.0) calculated: 57.27% C, 4.16% H, 7.22% N; foun d: 57.57% C,
4.01% H, 7.08% N. 1H NMR (250 MHz, DMSO-d6): 1.16 s, 9 H (3 Me); 4.60–4.84 m , 3 H
(H-4′, H-5′); 6.34–6.37, 6.42–6.47 2m , 2 H (H-3′, H-2′); 6.50 d, 1 H, J(1′,2′) = 3.6 (H-1′);
7.40–7.49 m , 6 H (arom H); 7.62–7.65 m , 3 H (arom H); 7.86–7.93 m , 6 H (arom H); 8.01 s,
1 H (H-6); 10.38 s, 1 H (NH).
4-Chloro-5-iodo-2-pivalamido-7-(2,3,5-tri-O-benzoyl-β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyri-
midine (18d ). As described for 18b , com poun d 18d was prepared from 4-ch loro-5-iodo-
2-pivalam ido-7H-pyrrolo[2,3-d]pyrim idin e (17d 21; 757 m g, 2.00 m m ol), ribose 16 (2.02 g,
4.00 m m ol), MeCN (14 m l), BSA (97%, 0.6 m l, 2.41 m m ol), an d TMSOTf (0.50 m l, 2.58 m m ol).
Com poun d 18d was obtain ed as
a yellowish foam (1.2 g, 73%). TLC (silica gel,
CH2Cl2/MeOH, 99:1): Rf 0.30. For C37H32ClIN4O8 (823.0) calculated: 54.00% C, 3.92% H,
6.81% N; foun d: 54.14% C, 4.30% H, 6.63% N. 1H NMR (250 MHz, DMSO-d6): 1.18 s, 9 H
(3 Me); 4.62–4.85 m , 3 H (H-4′, H-5′); 6.33–6.37 m , 1 H (H-3′); 6.42–6.47 m , 1 H (H-2′);
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
973
6.51 d, 1 H, J(1′,2′) = 3.7 (H-1′); 7.42–7.49 m , 6 H (arom H); 7.63–7.65 m , 3 H (arom H),
7.89–7.94 m , 6 H (arom H); 8.06 s, 1 H (H-6); 10.34 s, 1 H (NH).
5-Ch loro-4-m eth oxy-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -2-am in e (19b).
Gen eral Procedure for th e Preparation of 19b–19d
A solution of 18b (1.1 g, 1.50 m m ol) in 0.5 M MeONa/MeOH (20.0 m l) was h eated un der
reflux for 3 h . Th e reaction m ixture was n eutralized with 2 M AcOH, th e solven t was re-
m oved, an d th e residue was applied on to FC (silica gel, colum n 3 × 8 cm , elution with
CH2Cl2/MeOH, 95:5). Th e fraction s, con tain in g th e desired m aterial, were collected an d
evaporated to dryn ess to give com poun d 19b as a colorless solid (412 m g, 83%). TLC (silica
gel, CH2Cl2/MeOH, 9:1): RF 0.43. For C12H15ClN4O5 (330.7) calculated: 43.58% C, 4.57% H,
16.94% N; foun d: 43.58% C, 4.47% H, 16.95% N. UV (MeOH): 229 (27000), 264 (8500), 289
(6800). 1H NMR (250 MHz, DMSO-d6): 3.50–3.57 m , 2 H (H-5′); 3.79–3.82 m , 1 H (H-4′);
3.93 s, 3 H (OMe); 4.02–4.05 m , 1 H (H-3′); 4.24–4.26 m , 1 H (H-2′); 4.99 t, 1 H, J = 5.4
(OH-5′); 5.06 d, 1 H, J = 4.2 (OH-3′); 5.26 d, 1 H, J = 6.2 (OH-2′); 5.96 d, 1 H, J(1′,2′) = 6.4
(H-1′); 6.44 s, 2 H (NH2); 7.25 s, 1 H (H-6).
5-Bromo-4-methoxy-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-2-amine (19c). Com -
poun d 19c was prepared from n ucleoside 18c (1.17 g, 1.51 m m ol) as described for 19b. FC
resulted in a colorless solid (478 m g, 84%). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.45. For
C
12H15BrN4O5 (375.2): 38.42% C, 4.03% H, 14.93% N; foun d: 38.75% C, 4.20% H, 15.05% N.
UV (MeOH): 230 (29300), 264 (8700), 289 (7300). 1H NMR (250 MHz, DMSO-d6): 3.50–3.59
2 m , 2 H (H-5′); 3.82–3.84 m , 1 H (H-4′); 3.94 s, 3 H (OMe); 4.02–4.04 m , 1 H (H-3′);
4.27–4.28 m , 1 H (H-2′); 5.02 t, 1 H, J = 4.8 (OH-5′); 5.08 d, 1 H, J = 4.2 (OH-3′); 5.28 d, 1 H,
J = 6.2 (OH-2′); 5.98 d, 1 H, J(1′,2′) = 6.4 (H-1′); 6.43 s, 2 H (NH2); 7.30 s, 1 H (H-6).
5-Iodo-4-methoxy-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-2-amine (19d ). Com poun d
19d was prepared from com poun d 18d (1.23 g, 1.49 m m ol) as described for 19b. Colorless
solid (507 m g, 81%). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF 0.46. For C12H15IN4O5 (422.2)
calculated: 34.14% C, 3.58% H, 13.27% N; foun d: 34.55% C, 3.57% H, 13.29% C. UV (MeOH):
227 n m (24500), 265 (8000), 288 (7200). 1H NMR (250 MHz, DMSO-d6): 3.47–3.61 m , 2 H
(H-5′); 3.80–3.82 m , 1 H (H-4′); 3.93 s, 3 H (OMe); 4.01–4.03 m , 1 H (H-3′); 4.23–4.30 m ,
1 H (H-2′); 5.01 t, 1 H, J = 5.3 (OH-5′); 5.05 d, 1 H, J = 4.3 (OH-3′); 5.25 d, 1 H, J = 6.2
(OH-2′); 5.94 d, 1 H, J(1′,2′) = 6.4 (H-1′); 6.38 s, 2 H (NH2); 7.31 s, 1 H (H-6).
2-Am in o-5-ch loro-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -4(3H)-on e (5b).
Gen eral Procedure for th e Preparation of 5b–5d
Com poun d 19b (149 m g, 0.45 m m ol) was dissolved in 2 M NaOH (40 m l) an d 1,4-dioxan e
(6 m l). Th e m ixture was stirred un der reflux for 3 h . After n eutralization with 2 M HCl
followed by th e evaporation of 1,4-dioxan e, th e crude product was ch rom atograph ed on a
Serdolit AD-4 colum n (3 × 12 cm , resin 0.1–0.2 m m ; Serva, Germ an y). Th e in organ ic salt
was eluted with H2O (150 m l), an d th e product was eluted with H2O/i-PrOH (95:5, 500 m l).
Th e product con tain in g fraction s were collected an d th e solution was reduced to ca. 15 m l.
Com poun d 5b was crystallized from H2O as colorless crystals (114 m g, 80%), m .p. > 290 °C
(dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.22. For C11H13ClN4O5 (316.7) calculated:
41.72% C, 4.14% H, 17.69% N; foun d: 41.92% C, 4.46% H, 17.52% N. UV (MeOH): 221
(20900), 264 (11500), 290 (6000). 1H NMR (250 MHz, DMSO-d6): 3.44–3.56 m , 2 H (H-5′);
3.79–3.81 m , 1 H (H-4′); 4.00–4.02 m , 1 H (H-3′); 4.17–4.23 m , 1 H (H-2′); 4.97 t, 1 H, J =
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974
Seela, Peng:
5.1 (OH-5′); 5.04 d, 1 H, J = 4.1 (OH-3′); 5.26 d, 1 H, J = 6.1 (OH-2′); 5.86 d, 1 H, J(1′,2′) =
6.2 (H-1′); 6.39 s, 2 H (NH2); 7.06 s, 1 H (H-6); 10.52 s, 1 H (NH).
2-Amino-5-bromo-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one (5c). Th e
preparation of 5c followed th e protocol described for 5b em ployin g 19c (199 m g, 0.53 m m ol),
2
M NaOH (40 m l), an d 1,4-dioxan e (6 m l). Colorless crystals (163 m g, 85%), m .p. > 290 °C
(dec. H2O). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.23. For C11H13BrN4O5 (361.2) calcu-
lated: 36.58% C, 3.63% H, 15.51% N; foun d: 37.02% C, 3.82% H, 15.11% N. UV (MeOH):
222 (22000), 262 (11300), 289 (7200). 1H NMR (250 MHz, DMSO-d6): 3.49–3.58 m , 2 H
(H-5′); 3.81–3.82 m , 1 H (H-4′); 4.01–4.03 m , 1 H (H-3′); 4.20-4.23 m , 1 H (H-2′); 4.99 t, 1 H,
J = 5.3 (OH-5′); 5.05 d, 1 H, J = 4.3 (OH-3′); 5.27 d, 1 H, J = 5.2 (OH-2′); 5.87 d, 1 H,
J(1′,2′) = 6.4 (H-1′); 6.37 s, 2 H (NH2); 7.12 s, 1 H (H-6); 10.51 s, 1 H (NH).
2-Amino-5-iodo-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidin-4(3H)-one (5d ). Th e prepara-
tion of 5d followed th e protocol described for 5b em ployin g 19d (422 m g, 1.0 m m ol), 2
M
NaOH (60 m l), an d 1,4-dioxan e (10 m l). FC resulted in colorless crystals from H2O (355 m g,
87%), m .p. > 239 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.28. For C11H13IN4O5
(408.2) calculated: 32.37% C, 3.21% H, 13.73% N; foun d: 32.58% C, 3.19% H, 13.67% N.
UV (MeOH): 266 (11400), 289 (7200). 1H NMR (250 MHz, DMSO-d6): 3.52–3.59 m , 2 H
(H-5′); 3.83–3.85 m , 1 H (H-4′); 4.05–4.06 m , 1 H (H-3′); 4.21–4.24 m , 1 H (H-2′); 4.97–4.98 m ,
2 H (OH-5′, OH-3′); 5.21 d, 1 H, J = 6.1 (OH-2′); 5.87 d, 1 H, J(1′,2′) = 6.3 (H-1′); 6.29 s, 2 H
(NH2); 7.16 s, 1 H (H-6); 10.47 s, 1 H (NH).
5-Ch loro-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin e-2,4-diam in e (6b).
Gen eral Procedure for th e Preparation of 6b–6d
A suspen sion of 18b (732 m g, 1.0 m m ol) in dioxan e (30 m l) an d 25% NH3/H2O (70 m l) was
stirred in an autoclave at 120 °C for 24 h . Th e clear solution was reduced to 10 m l an d
stored in th e refrigerator for 24 h , th en com poun d 6b was crystallized from H2O affordin g
colorless n eedles (287 m g, 91%), m .p. 238 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 9:1): RF
0.20. For C11H14ClN5O4 (315.7) calculated: 41.85% C, 4.47% H, 22.18% N; foun d: 41.45% C,
4.35% H, 21.99% N. UV (MeOH): 228 (33000), 268 (10600), 289 (9000). 1H NMR (250 MHz,
DMSO-d6): 3.47–3.61 m , 2 H (H-5′); 3.80–3.82 m , 1 H (H-4′); 4.01–4.03 m , 1 H (H-3′);
4.22–4.27 m , 1 H (H-2′); 5.03 d, 1 H, J = 3.8 (OH-3′); 5.09 t, 1 H, J = 4.8 (OH-5′); 5.23 d, 1 H,
J = 4.9 (OH-2′); 5.83 s, 2 H (NH2); 5.90 d, 1 H, J(1′,2′) = 6.4 (H-1′); 6.34 s, 2 H (NH2); 7.10 s,
1 H (H-6).
5-Bromo-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamine (6c). Th e procedure de-
scribed for 6b was applied to 6c em ployin g 18c (512 m g, 0.66 m m ol), dioxan e (20 m l), an d
25% NH3/H2O (50 m l). Colorless crystals from H2O (200 m g, 85%), m .p. 238 °C (dec.). TLC
(silica gel, CH2Cl2/MeOH, 9:1): RF 0.20. For C11H14BrN5O4 (360.2) calculated: 36.68% C,
3.92% H, 19.44% N; foun d: 36.87% C, 3.78% H, 19.34% N. UV (MeOH): 229 (33100), 268
(10100), 288 (8800). 1H NMR (250 MHz, DMSO-d6): 3.46–3.59 2 m , 2 H (H-5′); 3.80–3.81 m ,
1 H (H-4′); 4.01–4.02 m , 1 H (H-3′); 4.22–4.29 m , 1 H (H-2′); 5.04 d, 1 H, J = 4.3 (OH-3′);
5.09 t, 1 H, J = 5.3 (OH-5′); 5.24 d, 1 H, J = 6.2 (OH-2′); 5.85 s, 2 H (NH2); 5.90 d, 1 H,
J(1′,2′) = 6.4 (H-1′); 6.29 br s, 2 H (NH2); 7.17 s, 1 H (H-6).
5-Iodo-7-(β-L-ribofuranosyl)-7H-pyrrolo[2,3-d]pyrimidine-2,4-diamine (6d ). Th e procedure de-
scribed for 6b was applied to 6d em ployin g 18d (1.14 g, 1.38 m m ol), dioxan e (40 m l), an d
25% NH3/H2O (90 m l). Colorless crystals from H2O (500 m g, 89%), m .p. 236 °C (dec.). TLC
(silica gel, CH2Cl2/MeOH, 9:1): RF 0.20. For C11H14IN5O4 (407.2) calculated: 32.45% C,
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Pyrrolo[2,3-d]pyrimidine β-L-Nucleosides
975
3.47% H, 17.20% N; foun d: 32.59% C, 3.51% H, 17.36% N. UV (MeOH): 231 (33000), 269
(10200), 289 (8900). 1H NMR (250 MHz, DMSO-d6): 3.47–3.57 m , 2 H (H-5′); 3.80–3.82 m , 1 H
(H-4′); 4.00–4.02 m , 1 H (H-3′); 4.26–4.28 m , 1 H (H-2′); 5.04 d, 1 H, J = 5.1 (OH-3′); 5.11 t,
1 H, J = 5.3 (OH-5′); 5.22 d, 1 H, J = 5.3 (OH-2′); 5.80 s, 2 H (NH2); 5.88 d, 1 H, J(1′,2′) = 6.3
(H-1′); 6.19 s, 2 H (NH2); 7.20 s, 1 H (H-6).
5-Brom o-4-m eth oxy-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -2(1H)-on e (20c)
To a solution of 19c (375 m g, 1.0 m m ol) in AcOH/H2O (v/v 1:7, 60 m l), a solution of
NaNO2 (170 m g, 2.46 m m ol) in H2O (2.0 m l) was added dropwise wh ile stirrin g at room
tem perature. The stirring was continued for 30 m in, and pH of the yellow solution was adjusted
to 7.0 with 25% aq. NH3. The solution was applied to a Serdolit AD-4 colum n (4 × 20 cm , resin
0.1–0.2 m m ; Serva, Germ an y). In organ ic salt was eluted with H2O (200 m l), an d th e product
with MeOH/H2O (1:1 v/v, 300 m l). Th e product-con tain in g fraction s were reduced to 20% of
its origin al volum e an d com poun d 20c was crystallized from H2O to yield colorless n eedles
(327 m g, 87%), m .p. 220 °C (dec. H2O). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.57. UV
(MeOH): 226 (23500), 287 (6400). For C12H14BrN3O6 (376.2) calculated: 38.32% C, 3.75% H,
11.17% N; foun d: 38.43% C, 3.86% H, 11.23% N. 1H NMR (250 MHz, DMSO-d6): 3.53–3.62 m ,
2 H (H-5′); 3.87–3.88 m , 1 H (H-4′); 3.99 s, 3 H (OMe); 4.04–4.07 m , 1 H (H-3′); 4.28–4.30 m ,
1 H (H-2′); 5.10–5.15 m , 2 H (OH-5′, OH-3′); 5.36 d, 1 H, J = 6.1 (OH-2′); 5.97 d, 1 H, J(1′,2′) =
5.2 (H-1′); 7.49 s, 1 H (H-6); 11.63 s, 1 H (NH).
5-Iodo-4-m eth oxy-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin -2(1H)-on e (20d )
Com poun d 20d was prepared from 19d (422 m g, 1.00 m m ol) as described for 20c. Colorless
n eedles from H2O (364 m g, 86%), m .p. 220 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1):
RF 0.57. For C12H14IN3O6 (423.2) calculated: 34.06% C, 3.33% H, 9.93% N; foun d: 33.98% C,
3.40% H, 9.87% N. UV (MeOH): 229 (23400), 287 (6100). 1H NMR (250 MHz, DMSO-d6):
3.50–3.57 m , 2 H (H-5′); 3.86–3.87 m , 1 H (H-4′); 3.97 s, 3 H (MeO); 4.03–4.05 m , 1 H
(H-3′); 4.27–4.29 m , 1 H (H-2′); 5.12–5.13 br s, 2 H (OH-5′, OH-3′); 5.33 d, 1 H, J = 5.9
(OH-2′); 5.93 d, 1 H, J(1′,2′) = 5.0 (H-1′); 7.48 s, 1 H (H-6); 11.55 s, 1 H (NH).
5-Brom o-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin e-2,4(1H,3H)-dion e (7c)
A solution of com poun d 20c (188 m g, 0.50 m m ol) in a m ixture of 2 M NaOH (40 m l) an d
1,4-dioxan e (6 m l) was h eated un der reflux for 40 h wh ile stirrin g. After n eutralization with
2
M HCl an d evaporation of 1,4-dioxan e, th e crude product was ch rom atograph ed on a
Serdolit AD-4 colum n (3 × 12 cm , resin 0.1–0.2 m m ; Serva, Germ an y). Th e colum n was
wash ed with H2O (150 m l), an d th e product was eluted with MeOH/H2O (1:1 v/v, 200 m l).
Th e volum e of th e product-con tain in g fraction s was reduced to 20% of th eir origin al
volum e. Com poun d 7c was crystallized from H2O as colorless crystals (127 m g, 70%), m .p.
220 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.40. For C11H12BrN3O6 (362.1) calcu-
lated: 36.48% C, 3.34% H, 11.60% N; foun d: 36.54% C, 3.46% H, 11.54% N. UV (0.1
M
NaH2PO4 in H2O): 222 (23900), 256 (10100), 285 (6500). 1H NMR (250 MHz, DMSO-d6):
3.60–3.62 m , 2 H (H-5′); 3.92–3.94 m , 1 H (H-4′); 4.00–4.02 m , 1 H (H-3′); 4.15–4.19 m , 1 H
(H-2′); 5.17–5.55 m , 3 H (OH-2′, OH-3′, OH-5′); 5.67 d, 1 H, J(1′,2′) = 6.4 (H-1′); 7.07 s, 1 H
(H-6); 10.59, 11.63 2 s, 2 H (2 NH).
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976
Seela, Peng:
5-Iodo-7-(β-L-ribofuran osyl)-7H-pyrrolo[2,3-d]pyrim idin e-2,4(1H,3H)-dion e (7d )
Com poun d 7d was prepared from 20d (351 m g, 0.83 m m ol) as described for 7c usin g 2
M
NaOH (60 m l) an d 1,4-dioxan e (10 m l). Colorless crystals from H2O (251 m g, 74%), m .p.
230 °C (dec.). TLC (silica gel, CH2Cl2/MeOH, 5:1): RF 0.40. For C11H12IN3O6 (409.1) calcu-
lated: 32.29% C, 2.96% H, 31.02% I, 10.27% N; foun d: 32.41% C, 3.12% H, 30.74% I,
10.20% N. UV (0.1 M NaH2PO4 in H2O): 224 (21700), 258 (9600), 285 (6800). 1H NMR
(250 MHz, DMSO-d6): 3.60–3.62 m , 2 H (H-5′); 3.93–3.94 m , 1 H (H-4′); 3.99–4.00 m , 1 H
(H-3′); 4.11–4.15 m , 1 H (H-2′); 5.18 d, 1 H, J = 3.8 (OH-3′); 5.35 d, 1 H, J = 6.2 (OH-2′);
5.68 m , 2 H (OH-5′, H-1′); 7.11 s, 1 H (H-6); 10.72 s, 1 H (NH); 11.61 br s, 1 H (NH).
We appreciate technical assistance of Ms E.-M. Albertmann and thank Ms S. Budow and Ms K. Xu
for the measurement of NMR spectra. We thank Prof. P. La Colla (Cagliary, Italy) and Idenix
Pharmaceuticals (Cambridge, U.S.A.) for the antiviral tests and Dr R. Storer, Dr G. Gosselin, and
Prof. J.-L. Imbach for helpful discussions. Part of the work was supported by European Community
(Project: Flavitherapeutics, QLK3-CT-2001-00506).
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