150
Kozai et al.
(2a). To a
9-(3-O-Benzoyl-2-O-benzyl-b-D-ribofuranosyl)-6-chloropurine
mixture of 6-chloro-9-(3-O-benzoyl-b-D-ribofuranosyl) purine (1a, 390 mg, 1 mmol)
and benzyl alcohol (1.04 mL, 10 mmol) in 1,4-dioxane (25 mL) were added triphenyl-
phosphine (1.05 g, 4 mmol) and TMAD (668 mg, 4 mmol). The solution was stirred
ꢁ
at 50 C overnight, then concentrated to a small volume. The residual solution
was chromatographed over a column of silica gel G (2.2 ꢀ 34 cm) using 25–50%
AcOEt in hexane (1.4 l) to give 12a as white crystals (231 mg, 48%), mp 167.5–
ꢁ
1
69.5 C. Anal Calcd for C H ClN O : C, 59.94; H, 4.40; N, 11.65. Found:
5
2
4
21
4
þ
C, 59.97; H, 4.49; N, 11.60. MS m=z: 450, 452 (M -CH O). UV l
nm: 265. H-NMR (600 MHz, CDCl ) d: 8.55 (1H, s, H8), 8.15–8.16 (2H, m, two
(MeOH)
max
2
1
3
of Ph), 8.10 (1H, s, H2), 7.63–7.66 (1H, m, one of Ph), 7.51–7.54 (2H, m, two of
0
Ph), 6.84–6.94 (5H, m, Ph), 5.91 (1H, d, J ¼ 8.2 Hz, H1 ), 5.90 (1H, d, J ¼ 5.2 Hz,
0
0
0
0
H3 ), 5.55 (1H, br s, 5 OH), 4.89–4.91 (1H, m, H2 ), 4.55–4.57 (2H, m, H4 and
0
one of CH ), 4.29 (1H, d, J ¼ 12.1 Hz, one of CH ), 3.97–4.00 (1H, m, H5 a),
2
2
0
3
.86–3.88 (1H, m, H5 b).
9-(3-O-Benzoyl-2-O-benzyl-5-O-trityl-b-D-ribofuranosyl)-6-chloropurine
(2b).
To
(
were added triphenylphosphine (1.05 mg, 4 mmol) and TMAD (688 mg, 4 mmol).
a mixture of 6-chloro-9-(3-O-benzoyl-5-O-trityl-b-D-ribofuranosyl)purine
1b, 633 mg, 1 mmol) and benzyl alcohol (1.04 mL, 10 mmol) in 1,4-dioxane (25 mL)
ꢁ
The solution was stirred at 50 C overnight, then concentrated to a small volume.
The residual solution was chromatographed over a column of silica gel G
(
5
2.5 ꢀ 45 cm) using 20–25% AcOEt in hexane (1.4 l) to give a caramel (411 mg,
þ
1
7%). MS m=z: 479, 481 (M -Tr). H-NMR (600 MHz, CDCl ) d: 8.10, 8.51 (each
3
1
C H CO), 7.48–7.52 (2H, m, two of C H CO), 7.22–7.44 (ca 15H, m, Tr), 6.95–
H, s, H2, H8), 8.11–8.13 (2H, m, two of C H CO), 7.62–7.65 (1H, m, one of
6
5
6
5
6
5
0
0
7
5
4
.11 (5H, m, Ph), 6.14 (1H, d, J ¼ 6.6 Hz, H1 ), 5.75 (1H, dd, J ¼ 3.0, 5.2 Hz, H3 ),
0
.04 (1H, dd, J ¼ 5.5, 6.6 Hz, H2 ), 4.63 (1H, d, J ¼ 12.4 Hz, one of CH C H ),
2
6
5
0
.54–4.56 (1H, m, H4 ), 4.45 (1H, d, J ¼ 12.4 Hz, one of CH C H ), 3.56 (1H, dd,
2
6
5
0
0
J ¼ 3.8, 10.7 Hz, H5 a), 3.49 (1H, dd, J ¼ 4.1, 10.4 Hz, H5 b).
0
2
10 mL) saturated with ammonia at 0 C was heated in a steel bomb at 120 C over-
-O-Benzyladenosine (3). A solution of 12a (250 mg, 0.52 mmol) in MeOH
ꢁ ꢁ
(
night, then ice-cooled. The solution was concentrated to a small volume and chromato-
graphed over a column of silica gel G (2.7 ꢀ 33 cm) using a 0–33% EtOH in CHCl .
3
Evaporation of the fraction and crystallization from CCl and CHCl gave white
3
4
ꢁ
[4]
ꢁ
crystals (173 mg, 93%). mp 150–151.5 C. (lit.
C H N O 0.7 H O: C, 55.19; H, 5.56; N, 18.93. Found: C, 55.09; H, 5.65; N,
147–150 C). Anal Calcd for
1
7
19
5
4
2
þ
1
1
8.94. MS m=z: 327 (M -CH O). UV l
(MeOH) nm: 261. H-NMR (600 MHz,
max
2
DMSO-d ) d: 8.33 (1H, s, H8), 8.09 (1H, s, H2), 7.35 (2H, br s, NH ), 7.15–7.22
6
2
0
0
(
5
5H, m, Ph), 6.07 (1H, d, J ¼ 6.3 Hz, H1 ), 5.46 (1H, dd, J ¼ 4.4, 7.4 Hz, 5 OH),
0
.35 (1H, d, J ¼ 5.2 Hz, 3 OH), 4.57 (2H, dd, J ¼ 12.1, 12.5 Hz, CH ), 4.55 (1H,
2
0
0
dd, J ¼ 4.9, 6.3 Hz, H2 ), 4.37 (1H, dt, J ¼ 3.0, 4.9 Hz, H3 ), 4.03–4.04 (1H, m,
0
0
0
H4 ), 3.67–3.69 (1H, m, H5 a), 3.55–3.59 (1H, m, H5 b).
Adenosine (4). A suspension of 13 (60 mg, 0.17 mmol) and palladium on
activated carbon (10%, 60 mg) in EtOH (20 mL) was stirred vigorously under H2