Sodium Bicarbonate → 2,5,6-Trichloro-3-(N-methoxyiminomethylidene)-1-(beta-D-ribofuranosyl)indole

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Reaction Steps

To a solution of 2,5,6-trichloro-3-formyl-1-(β-D-ribofuranosyl)indole (4.3, 103 mg, 0.27 mmol) in MeOH (5 mL) was added a solution of methoxylamine hydrochloride (27 mg, 0.32 mmol) and sodium bicarbonate (22 mg, 0.26 mmol) in water (1.0 mL). The resulting mixture was stirred at room temperature for 16 h, then the solvent was evaporated to provide a pale yellow residue. The residue was suspended in 10 mL of 5% aqueous sodium thiosulfate and extracted with EtOAc (2×25 mL). The combined organic extracts were washed with brine (10 mL), dried over MgSO4, filtered and evaporated to yield a yellow residue. The residue was subjected to column chromatography (40×350 mm) on C18 reverse-phase silica gel with 80% MeOH/H2O. The appropriate UV-active fractions were pooled and evaporated to yield a white powder. The powder was recrystallized from Et2O to yield 45 mg (41%) of 4.30 as a white crystalline solid: mp 197-198 C; Rf 0.4 (10% MeOH/CHCl3); 1H NMR (500 MHz, DMSO-d6) δ 8.57 (s, 1H), 8.27 (s, 1H), 8.17 (s, 1H), 5.93 (d, 1H), 5.42 (d, 1H, D2O exch.), 5.40 (t, 1H, D2O exch.), 5.27 (d, 1H, D2O exch.), 4.42 (q, 1H), 4.14 (m, 1H), 4.00 (d, 1H), 3.96 (s, 3H), 3.71 (m, 2H). 13C NMR (125 MHz, DMSO-d6) δ 141.84, 133.04, 129.74, 126.09, 125.03, 123.82, 121.70, 115.46, 105.59, 88.85, 86.13, 71.43, 69.65, 61.84, 61.09. HRMS (EI) m/z calcd. for C15H15Cl3N2O5 408.0047, found 408.0047. Anal calcd for C15H15Cl3N2O5: C, 43.98; H, 3.69; N, 6.84. Found: C, 43.79; H, 3.68; N, 6.61.

Provenance & Evidence