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Liu et al.
O6-(m-Bromobenzyl)guanine (5b): M.p. 210–212ꢀC. 1H NMR
(DMSO-d6): ꢀ 5.45 (s, 2H, ArCH2), 6.33 (s, 2H, NH2, exchanges with
D2O), 7.34–7.40 (t, J ¼ 8.1 Hz, 1H, Ar-5-H), 7.51–7.57 (t, J ¼ 8.8 Hz, 2H,
Ar-4-H and Ar-6-H), 7.71 (s, 1H, Ar-2-H), 7.84 (s, 1H, H-8), 12.47 (br, s,
1H, >NH, exchanges with D2O). HRMS calcd. forC 12H9BrN5O (M-
H)þ 319.0069, found 319.0058.
O6-(o-Bromobenzyl)guanine (5c): M.p. 248–250ꢀC. 1H NMR
(DMSO-d6): ꢀ 5.54 (s, 2H, ArCH2), 6.34 (s, 2H, NH2, exchanges with
D2O), 7.31–7.35 (t, J ¼ 8.1 Hz, 1H, Ar-4-H, orA-r5- H), 7.42–7.47 (t,
J ¼ 7.4 Hz, 1H, Ar-4-H, orAr-5- H), 7.63–7.65 (d, J ¼ 7.4 Hz, 1H, Ar-6-
H), 7.68–7.71 (d, J ¼ 8.1 Hz, 1H, Ar-3-H), 7.84 (s, 1H, H-8), 12.48 (br, s,
1H, >NH, exchanges with D2O). HRMS calcd. forC 12H9BrN5O (M-
H)þ 319.0069, found 319.0078.
O6-(p-Iodobenzyl)guanine (6a): M.p. 244–248ꢀC dec. 1H NMR
(DMSO-d6): ꢀ 5.45 (s, 2H, ArCH2), 6.28 (s, 2H, NH2, exchanges with
D2O), 7.31–7.33 (d, J ¼ 8.1 Hz, 2H, Ar-3-H and Ar-5-H), 7.74–7.77 (d,
J ¼ 8.1 Hz, 2H, Ar-2-H and Ar-6-H), 7.84 (s, 1H, H-8), 12.48 (br, s, 1H,
>NH, exchanges with D2O). HRMS calcd. forC 12H9IN5O (M-H)þ
366.9930, found 366.9920.
O6-(m-Iodobenzyl)guanine (6b): M.p. 203–205ꢀC (lit.,[13] 118–120ꢀC).
1H NMR (DMSO-d6): ꢀ 5.47 (s, 2H, ArCH2), 6.30 (s, 2H, NH2,
exchanges with D2O), 7.15–7.21 (t, J ¼ 7.4 Hz, 1H, Ar-5-H), 7.49–7.52
(d, J ¼ 8.1 Hz, 1H, Ar-6-H), 7.68–7.70 (d, J ¼ 8.1 Hz, 1H, Ar-4-H), 7.85(s,
1H, Ar-2-H), 7.88 (s, 1H, H-8), 12.52 (br, s, 1H, >NH, exchanges with
D2O).
O6-(o-Iodobenzyl)guanine (6c): M.p. 235–240ꢀC dec. 1H NMR
(DMSO-d6): ꢀ 5.45 (s, 2H, ArCH2), 6.34 (s, 2H, NH2, exchanges with
D2O), 7.12–7.14 (t, J ¼ 7.4 Hz, 1H, Ar-4-H, orA-r5- H), 7.43–7.48 (t,
J ¼ 7.4 Hz, 1H, Ar-4-H, orAr-5- H), 7.57–7.60 (d, J ¼ 7.4 Hz, 1H, Ar-6-
H), 7.84 (s, 1H, H-8), 7.92–7.94 (d, J ¼ 7.4 Hz, 1H, Ar-3-H), 12.48 (br, s,
1H, >NH, exchanges with D2O). HRMS calcd. forC 12H9IN5O (M-H)þ
366.9930, found 366.9918.
O6-( p-methoxybenzyl)guanine (7):[17] M.p. 175–180ꢀC dec. H NMR
1
(DMSO-d6): ꢀ 3.74 (s, OCH3), 5.40 (s, 2H, ArCH2), 6.30 (s, 2H, NH2,
exchanges with D2O), 6.91–6.94 (d, J ¼ 8.8 Hz, 2H, Ar-3-H and Ar-5-H),
7.43–7.46 (d, J ¼ 8.8 Hz, 2H, Ar-2-H and Ar-6-H), 7.80 (s, 1H, H-8),
12.44 (br, s, 1H, >NH, exchanges with D2O). HRMS calcd. for
C13H13N5O2 271.1069, found 271.1056.
O6-( p-methylbenzyl)guanine (8):[18] M.p. 212–215ꢀC. 1H NMR
(DMSO-d6): ꢀ 2.31 (s, 3H, ArCH3), 5.46 (s, 2H, ArCH2), 6.28
(s, 1H, NH2, exchanges with D2O), 7.31–7.33 (d, J ¼ 7.4 Hz, 2H, Ar-3-
H and Ar-5-H), 7.74–7.77 (d, J ¼ 8.1 Hz, 2H, Ar-2-H and Ar-6-H), 7.84