[NH2:1][C:2]1[N:10]=[C:9]2[C:5]([N:6]=[CH:7][N:8]2[CH2:11][CH2:12][CH2:13][CH2:14][B:15]([OH:17])[OH:16])=[C:4](Cl)[N:3]=1.Cl.[OH-:20].[Na+]>>[OH:16][B:15]([OH:17])[CH2:14][CH2:13][CH2:12][CH2:11][N:8]1[CH:7]=[N:6][C:5]2[C:4](=[O:20])[NH:3][C:2]([NH2:1])=[N:10][C:9]1=2The compound prepared in Example 3, 2-amino-6-chloro-9-(4-dihydroxyborylbutyl)purine, (0.5 g, 1.85 mmol) was added to aqueous HCl (5 mL, 2N), and the reaction mixture was heated to reflux for 5 hours. After cooling to room temperature, aqueous NaOH (10%) was added to neutralize the reaction mixture to pH 7. Water was evaporated under high vacuum, and methanol was added to the residue to remove the unreacted starting material. The remaining solid was washed with water (3×20 mL), then stirred in water overnight. After filtration, the product was air-dried for 2 days. Yield 81%; Wt. 0.38 g; mp 202°-205° C.; 1H NMR (DMSO-d6) 0.55-0.68 (t, B CH2), 1.20-1.32 (m, B CH2 CH2), 1.62-1.75 (m, B CH2 CH2 CH2), 3.88-3.98 (t, CH2 CH2 N), 6.33-6.50 (s, H2N C2 guanine), 7.40-7.45 (s, (HO)2 B), 7.68-7.71 (s, H C8 guanine), 10.47-10.53 (H N3 guanine). Electrospray Mass Spectrum (MH)+ (low resolution); Calcd. 252.12 (C9H14O3N5B); Found 252.10 (79 ppm).
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