Hydrochloric Acid → 1-[2-(Piperidin-1-yl)ethyl]-1,3-dihydro-2H-benzimidazol-2-one

Participants

Reaction Conditions

Reaction Steps

A solution of 1-isopropenyl-1,3-dihydro-2H-benzimidazol-2-one (35 g, 0.2 moles) in DMF (250 ml) was added dropwise to a suspension of 80% sodium hydride (6 g, 0.2 moles) in DMF (50 ml). The reaction mixture was first heated at 45° C. for 30 minutes, allowed to cool at room temperature, and an additional amount of 80% sodium hydride (7.2 g, 0.24 moles) was added. Then 1-(2-chloroethyl)piperidine hydrochloride (44.16 g, 0.24 moles) was added portionwise and the reaction mixture was heated at 80° C.-90° C. for 3 hours. The mixture was then cooled at room temperature, adjusted to pH 3 with 37% aqueous HCl, and heated to 80° C. for additional 2 hours. The reaction mixture was poured into water and washed with ethyl acetate. The aqueous phase was adjusted to pH 8-9 with a saturated sodium carbonate solution and extracted into ethyl acetate. The organic layer was taken to dryness to give an ivory solid which after crystallization from isopropyl ether afforded 22.9 g of the title compound. M.p. 123° C.-125° C.

Provenance & Evidence