Sodium Hydroxide → 6-[[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]thio]-5H-1,3-dioxolo[4,5-f]benzimidazole

Beteiligte Stoffe

Reaktionsschritte

14.8 g (76.7 mmol) of 5H-1,3-dioxolo[4,5-f]benzimidazole-6-thiol are suspended in 300 ml of alcohol and treated with 170 g (76.5 mmol) of 2-chloromethyl-4-methoxy-3,5-dimethylpyridine hydrochloride while cooling with ice. Thereafter, a solution of 6.0 g of sodium hydroxide in 150 ml of water is added dropwise thereto, the mixture is left to boil at reflux overnight and subsequently evaporated to dryness in vacuo. The residue is dissolved in 1000 ml of methylene chloride. The solution is washed firstly with 500 ml of 1.5N sodium hydroxide solution and then with 3×500 ml of water, dried over sodium sulphate and evaporated in vacuo. The crude product is purified on 300 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent. Crystallization from methylene chloride/petroleum ether gives 6-[[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]thio]-5H-1,3-dioxolo[4,5-f]benzimidazole of melting point 178°-179°.

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