Water → Isopropyl alcohol isopropyl ether

Participants

Reaction Conditions

Reaction Steps

2-Bromoacetyl-4-methoxypyridine (11.5 g, 0.05) and 2-chlorobenzimidazole (7.5 g, 0.05 mole) were dissolved in dimethylformamide (75 ml) and cooled to 2° C. K2CO3 (12 g, 0.08 mole) was added and the temperature rose to 9° C. as the suspension was stirred for 1/2 hour. The mixture was added to H2O (200 ml) giving a solid which was removed by filtration. The mother liquors were extracted with ethyl acetate and the solid was dissolved in the extracts. The organic solution was washed (brine) and dried (MgSO4) and purified by passage down a silica column and evaporated to dryness to give a sticky solid. Trituration with propan-2-ol/di-isopropyl ether gave 2-chloro-1-[2-(2-[4-methoxypyridyl])-2-oxoethyl]-benzimidazole (7.2 g). (b) A mixture of the product of step (a) (7.2 g) and thiourea (2.4 g) in ethanol (50 ml) was stirred at ambient temperature for 1/4 hour and heated at 60° C. for 2 hours. The solution was filtered and evaporated and the residue was dissolved in water and treated to excess with NH4OH to give a solid which was purified by chromatography on silica with ethyl acetate to give 2-mercapto-1-(2-(2-(4-methoxypyridyl))-2-oxoethyl)benzimidazole (2 g).

Provenance & Evidence