Phosphorus oxychloride → 5-[(3-Methylindolizin-1-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole

Participants

Reaction Conditions

Reaction Steps

To 10 ml of dichloroethane were added 1.08 g of 5-pyrrolidinocarbonyl-4,5,6,7-tetrahydrobenzimidazole hydrochloride and 1.18 ml of phosphorus oxychloride, and the mixture was stirred at 80° C. for 1 hour. At the same temperature 0.69 g of 3-methylindolizine in 2 ml of dichloroethane was added dropwise thereto during 15 minutes. The mixture was refluxed while stirring for 3 hours after that the mixture was poured into 20 ml of ice-water, and then the mixture was stirred at room temperature for 30 minutes. After liquid-liquid separation, the aqueous layer was washed with 10 ml of dichloromethane. Further, the aqueous layer was adjusted to a pH of about 9 with an aqueous 20% sodium hydroxide solution and then extracted with 20 ml of chloroform-methanol (4:1) twice. The organic layer was dried over anhydrous magnesium sulfate, and the solvent was removed off under reduced pressure. The residue was washed with 20 ml of dichloromethane-ethylacetate (3:1) to obtain 1.00 g of 5-[(3-methylindolizin-1-yl)carbonyl]-4,5,6,7-tetrahydrobenzimidazole.

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