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

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Reaction Steps

5.82 g of 5H-1,3-dioxolo[4,5-f]benzimidazole-6-thiol were suspended in 200 ml of ethanol and the suspension was treated with 7.1 g of 2-chloromethyl-4-ethoxy-3,5-dimethylpyridine hydrochloride while cooling with ice. Thereafter, a solution of 2.4 g of sodium hydroxide in 100 ml of water was added dropwise thereto, the mixture was left to boil at reflux overnight and subsequently evaporated to dryness in vacuo. The residue was dissolved in 500 ml of methylene chloride. The solution was washed firstly with 250 ml of 1.5N sodium hydroxide solution and then with 3×300 ml of water, dried over sodium sulfate and evaporated in vacuo. The product was purified on 150 g of silica gel using ethyl acetate/methylene choride (1:1) as the elution agent. Crystallization from acetonitrile gave 6-[[(4-ethoxy-3,5-dimethyl-2-pyridyl)methyl]thio]-5H-1,3-dioxolo [4,5-f]benzimidazole of melting point 184°-185°.

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