V. N. Belov, A. I. Savchenko, V. V. Sokolov, A. Straub, A. de Meijere
FULL PAPER
foam. Crystallization from EtOH/CH2Cl2 gave an analytical Al2O3, eluting with CH2Cl2/MeOH (100:1), gave (Z)-17 (220 mg,
sample with m.p. 186 °C. 1H NMR (CDCl3, two isomers in a ratio
of ca. 5:1, the signals of the major one are marked *): δ ϭ 4.82
53%) as a colorless solid, which was used in the last step without
further purification. H NMR (CDCl3): δ ϭ 1.03 (mc, 2 H), 1.29
1
(br. s, 2 H, NH2), 5.63*/5.66 (s, 2 H, NCH2), 6.92Ϫ7.08 (m, 3 H), (mc, 2 H), 1.51 (dd, J ϭ 6.9 and 1.8 Hz, 3 H), 4.49 (quint, J ϭ 6.7,
7.13Ϫ7.28 (m, 12 H), 7.38Ϫ7.42 (m, 5 H), 8.47/8.51* (dd, J ϭ 1.8 1 H, CHϭ), 5.79 (s, 2 H, NH2), 5.96 (s, 2 H, NCH2), 6.05 (dq, J ϭ
and 4.6 Hz, 1 H, 6Ј-H), 8.59/8.89* (br. d/dd, J ϭ 8.0/1.8 and 8.0,
1 H) ppm. IR (KBr): ν˜ ϭ 3478, 3377, 3052, 3028, 1638, 1586, 1571,
6.3 and 1.7 Hz, 1 H, OCHϭ), 6.92Ϫ7.10 and 7.18Ϫ7.28 (2 m, 5
H, 5-H and 4 H in o-FC6H4), 8.26 (s, 1 H, 6Ј-H), 8.58 (dd, J ϭ 1.6
1483, 1446, 1296, 1264, 1236, 1171, 1133, 1031, 1016. MS (EI): and 4.5 Hz, 1 H, 4-H), 8.94 (dd, J ϭ 1.6 and 8.0 Hz, 1 H, 6-H)
m/z (%) ϭ 511 (100) [Mϩ], 497 (17), 418 (16), 258 (22), 243 (57) ppm. 13C NMR (CDCl3): δ ϭ 9.2 (CH3), 11.4 (CH2), 44.7 (d, J ϭ
[Ph3Cϩ], 182 (23), 165 (22), 109 (16). C33H26FN5 (511.61): calcd. 5.1, NCH2), 59.8 (CϪO), 104.4 (CHϭ), 113.3 (C-3a), 115.20 (CH,
C 77.47, H 5.12, N 13.69; found C 77.74, H 5.26, N 13.44.
d, J ϭ 21.1, C-3Ј), 115.23 (C-5ЈЈ in the pyrimidine ring), 118.2 (CH,
C-5), 123.9 (d, J ϭ 3.6, C-1Ј), 124.1 (CH, d, J ϭ 3.8, C-5Ј), 128.9
(CH, d, J ϭ 3.8, C-4Ј or C-6Ј), 129.1 (d, J ϭ 7.9, C-6Ј or C-4Ј),
133.2 (CH, C-4), 134.1 (CHϭ), 141.6 (C-3), 142.0 (OCHϭ), 149.2
(CH, C-6), 151.5 (C-7a), 154.0 (CH in the pyrimidine ring), 160.1
(d, J ϭ 247, CF), 160.2 (C) ppm. MS (EI): m/z (%) ϭ 416 (19)
[Mϩ], 414 (59), 362 (48), 347 (95), 321 (30), 251 (16), 226 (12),
109 (100).
3-(4-Amino-5-propanoylpyrimidin-2-yl)-1-(2-fluorobenzyl)-1H-
pyrazolo[3,4-b]pyridine (18) and 3-[4-Amino-5-(3-ethoxypropanoyl)-
pyrimidin-2-yl]-1-(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine (19):
Pd/C (30 mg, 10% Pd in the oxidized form, Merck) in EtOH (6 mL)
was saturated with hydrogen by passing a slow stream of H2
through the suspension for 2 h. The mixture was heated under re-
flux under Ar for 2 h, and 16b (110 mg, 0.264 mmol) was then ad-
ded, followed by aq. HCl (1 , 0.5 mL), and heating was continued (Z)-3-[4-Amino-5-(1-hydroxycyclopropyl)pyrimidin-2-yl]-1-(2-
for 40 h. The catalyst was removed by filtration, washing with hot
EtOH (30 mL), and the solvent was evaporated. The residue was
fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine (Metabolite 1-OH). Hy-
drolysis of the Propenyl Ether (Z)-17: Aq. HCl (0.5 , 2.0 mL,
separated on Al2O3 (50 g) eluting with CH2Cl2. The substance 1.0 mmol) was added to
(75 mg) with the same Rf value as the starting material (0.8, 0.529 mmol) in MeOH (2 mL), and the mixture was heated at 55
CH2Cl2/MeOH, 60:1) turned out to be a 1:2 mixture (molar ratio) °C for 1.5 h. At first, (Z)-17 dissolved, and the product 1-OH then
of 16b and 18. Crystallization from EtOH gave the pure compound precipitated gradually. Most of the methanol was evaporated, the
18 (45 mg) with m.p. 219Ϫ220 °C in 64% yield (based on converted residue was neutralized with aq. NaOH (1 ), and the mixture was
16b). 1H NMR (CDCl3): δ ϭ 1.24 (t, J ϭ 7.2 Hz, 3 H), 3.00 (q,
extracted with EtOAc (3 ϫ 50 mL). The combined organic layers
a suspension of (Z)-17 (220 mg,
J ϭ 7.2 Hz, 2 H), 5.97 (s, 2 H, NCH2), 6.11 (br. s, 1 H, NH), were washed with brine, Al2O3 (20 g) was added, and the solvent
6.95Ϫ7.08 (m, 3 H), 7.15Ϫ7.30 (m, 2 H), 8.60 (dd, J ϭ 1.5 and 4.5 was evaporated. CH2Cl2 was added to the residue, and the suspen-
Hz, 1 H, 4-H), 8.82 (br. s, 1 H, NH), 8.91 (dd, J ϭ 1.5 and 8.0 Hz,
sion was concentrated to dryness once more. The residue was
placed on a column prepacked with Al2O3 (100 g) and eluted with
1 H, 6-H), 9.04 (s, 1 H, 6Ј-H) ppm. 13C NMR (CDCl3): δ ϭ 8.3
(CH3), 31.7 (CH2), 45.0 (d, J ϭ 2.6, NCH2), 110.0 (C-3a), 115.3 CH2Cl2/MeOH (50:1). The crude product was isolated as a color-
(CH, d, J ϭ 21.4, C-3Ј), 115.6 (C-5ЈЈ in the pyrimidine ring), 118.7 less solid (170 mg). Recrystallization from MeOH gave the pure
(CH, C-5), 123.8 (C, d, J ϭ 14.5, C-1Ј), 124.1 (d, J ϭ 3.8, C-5Ј), metabolite 1-OH (130 mg, 65%), m.p. 208Ϫ213 °C. The product
129.1 (CH, d, J ϭ 3.8, C-4Ј or C-6Ј), 129.2 (d, J ϭ 6.9, C-6Ј or C-
4Ј), 133.1 (CH, C-4), 140.9 (C-3), 149.4 (CH, C-6), 151.6 (C-7a),
159.6 (CH in the pyrimidine ring), 160.1 (d, J ϭ 247, CF), 162.4
(C), 200.9 (C) ppm. MS (EI): m/z (%) ϭ 376 (100) [Mϩ], 347 (42)
[Mϩ Ϫ Et], 281 (9), 226 (10), 109 (38). The substance with the
lower Rf value (0.7, CH2Cl2/MeOH, 60:1) was identified as 19
(21 mg), yield 25% (based on converted 16b), m.p. 174 °C (dec.,
was in all respects identical to the material isolated from rat hepato-
cyte suspensions.[1] 1H NMR ([D4]MeOH): δ ϭ 0.93 (mc, 2 H), 1.07
(mc, 2 H), 5.87 (s, 2 H, NCH2), 7.03Ϫ7.13 (m, 3 H), 7.14Ϫ7.21 (m,
1 H), 7.24 (dd, J ϭ 4.5 and 8.1 Hz, 1 H, 5-H), 8.14 (s, 1 H, H-6Ј),
8.56 (dd, J ϭ 1.5 and 4.5 Hz, 1 H, 4-H), 9.04 (dd, J ϭ 1.5 and 8.0
Hz, 1 H, 6-H) ppm. 13C NMR ([D6]DMSO): δ ϭ 12.8 (CH2), 44.2
(d, J ϭ 3.8, NCH2), 51.6 (CϪO), 114.8 (C-3a), 115.7 (CH, d, J ϭ
20.7, C-3Ј), 117.1 (C-5ЈЈ in the pyrimidine ring), 118.5 (CH, C-5),
1
EtOH). H NMR (CDCl3): δ ϭ 1.19 (t, J ϭ 7.0 Hz, 3 H), 3.23 (t,
J ϭ 6.3 Hz, 2 H), 3.54 (q, J ϭ 7.0 Hz, 2 H), 3.85 (t, J ϭ 6.3 Hz, 2 124.2 (d, J ϭ 14.5, C-1Ј), 124.8 (CH, d, J ϭ 3.8, C-5Ј), 130.1 (CH,
H), 5.97 (s, 2 H, NCH2), 6.13 (br. s, 1 H, NH), 6.92Ϫ7.08 (m, 3 d, J ϭ 7.5, C-4Ј or C-6Ј), 130.3 (d, J ϭ 4.4, C-6Ј or C-4Ј), 133.5
H), 7.15Ϫ7.30 (m, 2 H), 8.59 (dd, J ϭ 1.5 and 4.5 Hz, 1 H, 4-H),
8.80 (br. s, 1 H, NH), 8.92 (dd, J ϭ 1.5 and 8.0 Hz, 1 H, 6-H), in the pyrimidine ring), 158.9 (C), 160.1 (d, J ϭ 247, CF), 163.0
9.06 (s, 1 H, 6Ј-H) ppm. 13C NMR (CDCl3): δ ϭ 15.8 (CH3), 38.7
(C) ppm. IR (KBr): ν˜ ϭ 3482, 3288, 3155, 3017, 1632, 1545, 1491,
(CH2), 45.0 (d, J ϭ 5.3, NCH2), 65.5 (CH2O), 66.6 (CH2O), 110.4 1458, 1230. MS (EI): m/z (%) ϭ 376 (100) [Mϩ], 347 (39) [Mϩ
(C-3a), 115.3 (CH, d, J ϭ 19.5, C-3Ј), 115.7 (C-5ЈЈ in the pyrimid-
Et], 281 (10) [Mϩ Ϫ C5H5NO], 226 (9), 109 (40) [C7H6Fϩ].
ine ring), 118.7 (CH, C-5), 123.8 (C, d, J ϭ 14.5, C-1Ј), 124.1 (d, C20H17FN6O (376.40): calcd. C 63.82, H 4.55; found C 63.66, H
(CH, C-4), 141.7 (C-3), 149.4 (CH, C-6), 151.0 (C-7a), 152.8 (CH
Ϫ
J ϭ 3.8, C-5Ј), 129.1 (CH, d, J ϭ 3.8, C-4Ј or C-6Ј), 129.3 (d, J ϭ
8.2, C-6Ј or C-4Ј), 133.1 (CH, C-4), 140.8 (C-3), 149.4 (CH, C-6),
151.6 (C-7a), 160.1 (CH in the pyrimidine ring), 160.1 (d, J ϭ 247,
CF), 162.5 (C), 198.5 (C) ppm.
4.52.
Direct Cleavage of Allyl Ether 16b with Grignard Reagents in the
Presence of Ti(OiPr)4: A solution of cyclohexylmagnesium bromide
in diethyl ether (1.9 , 0.58 mL, 1.1 mmol) was added at 10 °C to
a solution of 16b (434 mg, 1.04 mmol) in THF (25 mL), followed
by Ti(OiPr)4 (304 mg, 1.07 mmol). The dropwise addition of cyclo-
(Z)-3-(4-Amino-5-{1-[(1-propenyl)oxy]cyclopropyl}pyrimidin-2-yl)-1-
(2-fluorobenzyl)-1H-pyrazolo[3,4-b]pyridine
[(Z)-17]:
tBuOK
(224 mg, 2.00 mmol) was added under N2 at ambient temp. to a hexylmagnesium bromide was then continued at 10 °C until
solution of 16b (416 mg, 1.00 mmol) in anhydrous DMSO 2.32 mL (4.41 mmol) had been added over 1 h, and the mixture
(4.5 mL), and the mixture was heated at 90 °C for 1.5 h. After was then stirred for an additional 2 h. It was poured into a 1:1
cooling, it was diluted with ice/water (15 mL) and extracted with
EtOAc (3 ϫ 50 mL). The resulting brown solution was washed with
water (10 mL) and brine (10 mL) and dried. Chromatography on
mixture of brine and cold water (50 mL), the aqueous mixture was
extracted with EtOAc (4 ϫ 80 mL), and the combined organic
layers were washed with brine and dried. After evaporation of the
558
Eur. J. Org. Chem. 2003, 551Ϫ561