Short Communication
1389
Deprotection of the 6-Cyanopurines III – General Procedure
To a solution of the protected 6-cyanopurine derivative III (1 mmol) in methanol (40 ml), Dowex
+
5
0X8 (H ) (2 g) and water (10 ml) were added and the mixture was refluxed for 1 h. After cooling
to room temperature 35% aq. NH (1 ml) was added, the suspension was filtered and the resin was
3
washed with methanol (20 ml). The collected filtrates were evaporated to dryness to afford pure
6
-cyanopurine IV.
-Cyanopurine (IVa), yield 95%, m.p. 167–170 °C (toluene) (ref. 177–178 °C), R (MeOH–CHCl
: 9) 0.17. EI MS, m/z (rel.%): 145 (100) [M] . H NMR spectrum: 8.65 s, 1 H (H-8); 9.04 s, 1 H
2
a
6
F
3
+
1
1
(
H-2). UV (MeOH), λmax (ε): 288 nm (6 900). For C H N (145.1) calculated: 49.66% C, 2.08% H,
6 3 5
4
8.26% N; found: 49.22% C, 2.08% H, 47.98% N.
-Amino-6-cyanopurine (IVb), yield 94%, decomp. > 300 °C (ref. m.p. > 300 °C), R (MeOH–CHCl
: 4) 0.47. EI MS, m/z (rel.%): 160 (100) [M] . H NMR spectrum: 6.93 brs, 2 H (NH ); 8.32 s, 1 H
2
2b
2
F
3
+
1
1
(
(
H-8); 13.10 brs, 1 H (NH). UV (MeOH), λmax (ε): 355 nm (4 500); 266 nm sh (700). For C H N
6 4 6
160.1) calculated: 45.00% C, 2.52% H, 52.48% N; found: 45.24% C, 2.49% H, 52.72% N.
This work was supported by the Grant No. 455407 of the Grant Agency of the Czech Academy of
Sciences, by the Grant No. 203/93/0118 of the State Grant Agency of the Czech Republic and by Gilead
Sciences (Foster City, CA, U.S.A.). The authors thank Dr M. Masojidkova of our Institute for measuring
and interpretation of NMR spectra.
REFERENCES
1
2
.
.
For a review see: Shaw G. in: Comprehensive Heterocyclic Chemistry (A. R. Katritzky and A.
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9
.
Estep K. G., Josef K. A., Bacon E. R., Carabates P. M., Rumney S. IV, Pilling G. M., Krafte D.
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Note Added in Proof
9
After submission of this manuscript a paper by Estep et al. has appeared reporting the preparation of
the compound IIIa from IIa in 32% yield using potassium cyanide in DMSO.
Collect. Czech. Chem. Commun. (Vol. 60) (1995)