**Preparation of Chemical Reagents - N2, N2-Dimethylguanosine** Published: September 3, 2014 at 8:41 AM **Chinese Name:** N2, N2-二甲基鸟苷 **English Name:** N2, N2-Dimethylguanosine **Alternative Names:** 2-Dimethylamino-9-β-D-ribofuranosyl-6-one oxime; 2-Dimethylamino-9-β-D-ribofuranosylpurin-6-one **Molecular Formula:** C₁₂H₁₇N₅O₅ **Molecular Weight:** 311.33 g/mol **Physical and Chemical Properties:** Melting point around 242°C (decomposes). pKa values are approximately 2.5 (for the basic group) and 9.7 (for the acidic group). **Preparation Method:** The synthesis of N2, N2-dimethylguanosine involves several steps. First, 250 mg (0.87 mmol) of 2-fluoroinosine (I) was dissolved in 30 mL of absolute ethanol and 40 mL of anhydrous dimethylamine. The mixture was refluxed for 30 minutes, then concentrated under reduced pressure. The residue was dissolved in 5 mL of hot water (with a few drops of concentrated ammonia), boiled, treated with activated carbon, filtered, and washed with hot water twice. The filtrate was adjusted to a slightly acidic pH using 25% formic acid, cooled overnight, and filtered to yield 150 mg (55%) of colored needle-like crystals. In another step, 2.5 g (0.008 mol) of 2-fluoro-9-β-D-ribofuranosyl-6-thione was prepared from 2-fluoro-6-deuterated nucleoside (III). The nucleoside was dissolved in 10 mL of 50% dimethylamine in ethanol, left at room temperature for one hour, and then distilled under reduced pressure. After adding 25 mL of water and neutralizing with 25% formic acid, an oily product was obtained. This oil was extracted under reduced pressure and mixed with 1.25 g (70%) of 2-dimethylamine-9-β-D-ribofuranosyl-6-thione (IV), resulting in a crude product that could be recrystallized from water. Next, 500 mg (1.5 mmol) of III was dissolved in 10 mL of 28% ammonium hydroxide, and 20 mL of 30% hydrogen peroxide was added dropwise while maintaining a temperature of 25°C in a water bath. The mixture was stirred at room temperature for 24 hours, filtered, and the filtrate was dried under reduced pressure. After trituration with ethanol and filtration, the final product (II) was obtained. Additionally, the preparation of 2-mercaptoinosine involved dissolving 10 g (38.8 mmol) of 5-amino-1-β-D-ribofuranosyl-4-imidazolecarboxamide (V) in a solution of 7.75 g (194 mmol) sodium hydroxide in 70 mL methanol. Then, 14.7 g (194 mmol) of carbon disulfide was added, and the mixture was heated under high pressure in an oil bath at 180°C for 3 hours. After cooling, filtering, washing with cold methanol, and recrystallization from water, 8.2 g (64%) of 2-mercaptoinosine sodium salt was obtained. Further processing yielded colorless crystals of N2,N2-dimethylguanosine (II) after treatment with hydrogen peroxide and dimethylamine.

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