28
C.V.N.S. Varaprasad et al. / Bioorganic Chemistry 35 (2007) 25–34
chromatography using CH Cl and MeOH as eluants with increasing polarity to obtain 4-
2
2
1
methylamino-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile 10 (63%).
H
NMR (CD OD): d 8.13 (s, 1H), 8.02 (s, 1H), 6.00 (d, J = 6.3 Hz, 1H), 4.62 (dd,
3
J = 5.4, 6.3 Hz, 1H), 4.27 (dd, J = 3.0, 5.4 Hz, 1H), 4.13 (dd, J = 3.0, 6.0 Hz, 1H), 3.80
+
(
ddd, J = 2.4, 12.3 and 33.2 Hz, 2H), 3.05 (s, 3H). ES-MS (m/z+1) : 306.
2
.6. 4-Chloro-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (9)
-Chloro-7-(2,3,5-tri-O-acetyl-b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitri-
4
le 8 (1.9 g, 4.36 mmol) was treated with a cold (À20 ꢁC) solution of saturated methanolic
ammonia and the reaction mixture kept at 5 ꢁC for 2.5 h with occasional shaking. The vol-
atiles evaporated and the residue was purified over flash silica gel chromatography using
CH Cl and MeOH mixture with increasing polarity to obtain the title product (1.1 g,
2
2
1
8
1.5%). H NMR (CD OD): d 8.16 (s, 1H), 8.01 (s, 1H), 6.12 (d, J = 5.4 Hz, 1H), 4.40
3
(
(
t, J = 5.4 Hz, 1H), 4.27 (t, J = 3.9, 5.4 Hz, 1H), 4.09 (dd, J = 3.0, 6.6 Hz, 1H), 3.80
ddd, J = 2.7, 12.0 and 32 Hz, 2H). ES-MS (m/z+1) : 312.
+
2
.7. 4-Dimethylamino-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (16)
To a solution of 4-chloro-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile
9
(0.3 g, 0.96 mmol) in EtOH (10 ml) a solution of dimethylamine (10 ml, 2 M) in THF
was added and the reaction mixture was refluxed for 1 h. The volatiles evaporated and
the residue was purified by flash silica gel chromatography using CH Cl /MeOH mixture
2
2
1
with increasing polarity to obtain the titled product (0.2 g, 65.15%). H NMR (CD OD): d
3
8
.34 (s, 1H), 8.24 (s, 1H), 6.13 (d, J = 5.1 Hz, 1H), 4.52 (t, J = 5.1 Hz, 1H), 4.27 (dd,
J = 3.9, 5.1 Hz, 1H), 4.12 (dd, J = 2.7, 6.6 Hz, 1H), 3.82 (ddd, J = 2.4, 12.3 and
+
3
7.5 Hz, 2H), 3.39 (s, 6H). ES-MS (m/z+1) : 320.
2
.8. 4-O-Methyl-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (17)
A solution of 4-chloro-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile 9
(
0.310 g, 1 mmol) and sodium methoxide (0.054 g, 5 mmol) in methyl alcohol (10 ml)
was refluxed for 16 h. The reaction mixture was cooled to room temperature and volatiles
evaporated. The residue was purified over flash silica gel chromatography (CH Cl /MeOH
2
2
1
mixture as eluant) to obtain the titled product (0.16 g, 52%) as a white solid. H NMR
CD OD): d 8.77 (s, 1H), 8.58 (s, 1H), 6.20 (d, J = 5.4 Hz, 1H), 4.53 (t, J = 5.4 Hz,
(
3
1
1
H), 4.22 (dd, J = 3.9, 4.8 Hz, 1H), 4.13 (dd, J = 3.0, 7.2 Hz, 1H), 3.80 (ddd, J = 2.7,
2.3 and 34.2 Hz, 2H), 4.02 (s, 3H). ES-MS (m/z+1) : 307.
+
2
.9. 4-Methylthio-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile (18)
A suspension of 4-chloro-7-(b-D-ribofuranosyl)pyrrolo[2,3-d]pyrimidine-5-carbonitrile
9
(0.310 g, 1 mmol) and sodium methanethiolate (0.105 g, 1.5 mmol) in isopropyl alcohol
(
10 ml) was refluxed for 1 h. The reaction mixture cooled to room temperature and vola-
tiles evaporated. The residue was purified over flash silica gel chromatography (CH Cl /
2
2
1
MeOH mixture as eluant) to obtain the titled product (0.23 g, 72%) as a white solid. H
NMR (CD OD): d 8.67 (s, 1H), 8.48 (s, 1H), 6.23 (d, J = 5.4 Hz, 1H), 4.51 (t,
3