Réaction #63754

Équation de réaction

sodium hydroxide

2-benzimidazolethiol

2-chloromethyl-4-methoxy-3.5-dimethylpyridine hyrochloride

→

2-[[(4-methoxy-3,5 -dimethyl-2-pyridyl)methyl]thio]benzimidazole

Solvants

—

alcohol

water

Conditions de réaction

Traitement

1. 1
   Températurewhile cooling with ice
2. 2
   workup.WAITthe mixture is left
3. 3
   Températureat reflux overnight
4. 4
   Autresubsequently evaporated to dryness in vacuo
5. 5
   workup.DISSOLUTIONThe residue is dissolved in 2.0 l of methylene chloride
6. 6
   LavageThe solution is washed firstly with 600 ml of 1.5N sodium hydroxide solution
7. 7
   Séchage3× with 2.2 l of water, dried over sodium sulphate
8. 8
   Autreevaporated in vacuo
9. 9
   AutreThe crude product is purified on 1300 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent
10. 10
    AutreCrystallization from methylene chloride/petroleum ether

Mode opératoire

64.8 g of 2-benzimidazolethiol are suspended in 400 ml of alcohol and treated with 95.9 g of 2-chloromethyl-4-methoxy-3.5-dimethylpyridine hyrochloride while cooling with ice. Thereafter, a solution of 34.5 g of sodium hydroxide in 1.5 l 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 2.0 l of methylene chloride. The solution is washed firstly with 600 ml of 1.5N sodium hydroxide solution and then 3× with 2.2 l of water, dried over sodium sulphate and evaporated in vacuo. The crude product is purified on 1300 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent. Crystallization from methylene chloride/petroleum ether gives 2-[[(4-methoxy-3,5 -dimethyl-2-pyridyl)methyl]thio]benzimidazole of melting point 129°-131°.

Source