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with Na2SO2, filtered and evaporated. The crude crystalline product
(0.67 g, 96%) was crystallized from iso-PrOH (9 ml) and EtOH (8 ml).
Light yellow-brownish crystals. M. p.: 153e156 ꢀC. Elem. anal.
(Found: C, 55.8; H, 5.6; N, 23.0. C16H19N5O2S requires: C, 55.6; H,
5.5; N, 23.3%).
Yellowish, amorphous product. Yield: 84 mg (79%). Elem. anal.
(Found: C, 55.6 H, 7.5; N, 38.0. C12H19N7 requires: C, 55.2; H, 7.3; N,
37.5%).
8-(3-aminopropylamino)-6-(3-methylbut-2-en-1-ylamino)
purine (39). CC (mobile phase CHCl3-MeOH-NH4OH 7:3:0.3).
Yellowish, amorphous product. Yield 126 mg (98%). Elem. anal.
(Found: C, 57.1 H, 7.2; N, 35.1. C13H21N7 requires: C, 56.7; H, 7.7; N,
35.6%).
4.3.13. Synthesis of 8-methoxy-6-(3-methylbut-2-en-1-ylamino)-
9-(tetrahydropyran-2-yl)-9H-purine (X)
Compound 5 (248 mg, 0.68 mmol) was added to a soln. of KOtBu
(103 mg, 0.98 mmol) in dry MeOH (7 ml). The soln. was heated at
45 ꢀC for 13 h and after cooling, placed in a refrigerator overnight,
then filtered and evaporated. The crude product was purified by CC
(mobile phase CHCl3-Me2CO 9:1. Viscous, yellow substance. Yield
170 mg (79%). The product contained ca. 30% of impurities.
Therefore, elemental analysis was not performed and the product
was used directly in the next synthesis (compound 35).
8-(4-aminobutylamino)-6-(3-methylbut-2-en-1-ylamino)
purine (40). CC (mobile phase CHCl3-MeOH-NH4OH 3:1:2.5).
Yellowish, amorphous product. Yield 108 mg (75%). Elem. anal.
(Found: C, 58.5 H, 8.3; N, 34.4. C14H23N7 requires: C, 58.1; H, 8.0; N,
33.9%).
8-(2-hydroxyethylamino)-6-(3-methylbut-2-en-1-ylamino)
purine (41). Crystallized from MeOH. White powder. Yield 41 mg
(59%). M. p.: 228e230 ꢀC. Elem. anal. (Found: C, 54.5 H, 6.6; N, 31.5.
C12H18N6O requires: C, 55.0; H, 6.9; N, 32.0%).
4.3.14. Synthesis of 6-furfurylamino-8-(2-hydroxyethyloxy)-9-
(tetrahydropyran-2-yl)-9H-purine (XI)
8-chloro-6-furfurylaminopurine (45). Crude product was
dissolved in MeOH satd. with NH3 at 0 ꢀC (3 ml), diluted with MeOH
(1 ml), partly evaporated and left to crystallize in a refrigerator to
give a beige powder. Yield 23 mg (19%). M. p.: 276e278 ꢀC. Elem.
anal. (Found: C, 48.0 H, 3.2; N, 28.0. C10H8ClN5O requires: C, 48.1; H,
3.2; N, 28.1%).
KOtBu (122 mg, 1.08 mmol) was added to a suspension of
compound 16 (261 mg, 0.78 mmol) in dry ethylene glycol (2.4 ml)
and THF (0.4 ml). The suspension was heated at 45 ꢀC overnight and
the resulting rusty soln. was heated for another 8.5 h at 60 ꢀC. The
soln. was evaporated and purified by CC (mobile phase CHCl3-
Me2CO 3:1). Rusty, viscous substance. Yield 307 mg (>100% theory).
According to TLC, the product contained impurities and was used
without detailed characterization for the synthesis of compound
58.
8-bromo-6-furfurylaminopurine (46). Crystallized from
MeOH to give a beige powder. Yield 97 mg (66%). M. p.: 239e240 ꢀC.
Elem. anal. (Found: C, 40.9 H, 2.6; N, 23.5. C10H8BrN5O requires: C,
40.8; H, 2.7; N, 23.8%).
6-furfurylamino-8-iodopurine (47). Beige powder. Yield
172 mg (97%). M. p.: 220e222 ꢀC. Elem. anal. (Found: C, 35.0 H, 2.5;
N, 20.7. C10H8IN5O requires: C, 35.2; H, 2.4; N, 20.5%).
Synthesis of 6-furfurylamino-8-methoxypurine (49). The
residuum was crystallized from MeOH (2 ml) with filtration. The
soln. was placed into a refrigerator for 2 days and then solid im-
purities were removed by decantation. The mother liquor was
diluted with MeOH and H2O and partly evaporated until cotton
wool-like crystals appeared. The mother liquor was placed into a
refrigerator overnight and then resulting crystals were filtered off
and dried. Light beige crystals. Yield 50 mg (60%). M. p.:
196e198 ꢀC. Elem. anal. (Found: C, 53.7 H, 4.4; N, 28.7. C11H11N5O2
requires: C, 53.9; H, 4.5; N, 28.6%).
6-furfurylamino-8-methylsulfanylpurine (50). Light beige
needle crystals. Yield (I) 64 mg (42%). M. p.: 226e228 ꢀC. A second
portion of the product was obtained from the concentrated mother
liquor. Yield (II) 54 mg (36%). Elem. anal. (Found: C, 50.3 H, 4.4; N,
26.6. C11H11N5OS requires: C, 50.6; H, 4.2; N, 26.8%).
4.3.15. General procedures for the cleavage of a THP group
(synthesis of compounds 28e33, 35e42, 45e47, 49e58)
4.3.15.1. Procedure A (synthesis of compounds 28, 30, 35e41, 45e47,
49, 50, 52e58).
8-Substituted-9-(tetrahydropyran-2-yl)cytokinin
(0.07e0.78 mmol) was dissolved in HOAc-H2O (4:1 or 5:3,
1.6e2.0 ml) and stirred at room temp. overnight for 2 days. The
mixture was evaporated to dryness. The residuum was dissolved in
H2O-EtOH 2:1, and evaporated. This procedure was repeated ꢂ3 to
facilitate removal of HOAc. The crude product was crystallized from
alcohol and/or purified by CC (details are given separately for each
substance) and dried in a desiccator with P2O5. This procedure was
applied to synthesize the following compounds:
(E)-8-chloro-6-(4-hydroxy-3-methylbut-2-en-1-ylamino)pu-
rine (28). CC (mobile phase CHCl3, on TLC Rf ¼ 0.16). White crystals.
Yield 96 mg (75%). M. p.: 236e238 ꢀC. Elem. anal. (Found: C, 47.5; H,
4.8; N, 27.7. C10H12ClN5O requires: C, 47.4; H, 4.8; N, 27.6%).
(E)-6-(4-hydroxy-3-methylbut-2-en-1-ylamino)-8-
6-furfurylamino-8-dimethylaminopurine (52). After de-
protection, the mixture was neutralized with satd. aq. NH3
(2.0 ml). The suspension was placed into a refrigerator overnight,
the solid precipitate was filtered off and crystallized from MeOH
(5 ml, with filtration). To initiate crystallization, partial evaporation
of MeOH was necessary. Recrystallization from a mixture of conc.
NH4OH-MeOH-H2O gave white, fibrous crystals. Yield 52 mg (70%).
M. p.: 245e246 ꢀC. Elem. anal. (Found: C, 55.9 H, 5.5; N, 32.5.
dimethylaminopurine (30). CC (mobile phase CHCl3, on TLC
Rf ¼ 0.05). White crystals. Yield 64 mg (85%). M. p.: 245e249 ꢀC.
Elem. anal. (Found: C, 54.7; H, 6.8; N, 31.6. C12H18N6O requires: C,
55.0; H, 6.9; N, 32.0%).
8-methoxy-6-(3-methylbut-2-en-1-ylamino)purine
(35).
Crystallized from iso-PrOH (3 ml) to give a white powder. Yield
34 mg (33%). M. p.: 205e210 ꢀC. Elem. anal. (Found: C, 56.8 H, 6.4;
N, 30.1. C11H15N5O requires: C, 56.6; H, 6.5; N, 30.0%).
C
12H14N6O requires: C, 55.8; H, 5.5; N, 32.5%).
8-(2-aminoethylamino)-6-furfurylaminopurine (53). CC
8-amino-6-(3-methylbut-2-en-1-ylamino)purine (36). CC
(mobile phase CHCl3-MeOH-NH4OH 9:1:0.1). White crystals. Yield
6 mg (41%). M. p.: 254e262 ꢀC (decomp.). Elem. anal. (Found: C,
54.8 H, 6.4; N, 38.4. C10H14N6 requires: C, 55.0; H, 6.5; N, 38.5%).
8-dimethylamino-6-(3-methylbut-2-en-1-ylamino)purine
(37). Crude product was crystallized from MeOH. White, cotton-like
crystals. Yield 46 mg (68%). M. p.: 246e249 ꢀC. Elem. anal. (Found:
C, 58.6 H, 7.2; N, 34.4. C12H18N6 requires: C, 58.5; H, 7.4; N, 34.1%).
8-(2-aminoethylamino)-6-(3-methylbut-2-en-1-ylamino)pu-
rine (38). CC (mobile phase CHCl3-MeOH-NH4OH 3:1:2.5).
(mobile phase CHCl3-MeOH-NH4OH 7:3:0.3). Yellowish, glassy
substance. Yield 24 mg (88%). M. p.: 105e110 ꢀC. Elem. anal. (Found:
C, 52.2 H, 5.6; N, 35.7. C12H15N7O requires: C, 52.7; H, 5.5; N, 35.9%).
6-furfurylamino-8-(2-hydroxyethylamino)purine (54). White
plaster solid. Yield 52 mg (78%). M. p.: 230e233 ꢀC. Elem. anal.
(Found: C, 52.1 H, 4.8; N, 30.7. C12H14N6O2 requires: C, 52.6; H, 5.1;
N, 30.6%).
6-furfurylamino-8-(3-hydroxypropylamino)purine (55). The
product (110 mg) was crystallized from CHCl3-MeOH (95:5, 3 ml) to
give a white powder. Yield (I) 25 mg (25%). M. p.: 201e203 ꢀC. A
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Please cite this article in press as: Zahajska, L., et al., Preparation, characterization and biological activity of C8-substituted cytokinins,