O-Phenylenediamine → 2-[[1-(phenylmethyl)-4-piperidinyl]methyl]-1H-benzimidazole

Participants

Reaction Steps

To 73 parts of hot (70° C.) polyphosphoric acid were added 27 parts of 1-(phenylmethyl)-4-piperidineacetic acid hydrochloride: temperature rose to 100° C. When the addition was complete, there were added portionwise 14 parts of 1,2-benzenediamine and stirring and heating was continued for 50 minutes at 170° C. The hot reaction mixture was poured into 300 parts of warm water. The acid solution was alkalized with a potassium hydroxide solution. The precipitated free base was filtered off, washed with water and extracted with trichloromethane. The extract was dried and evaporated. The solid residue was recrystallized from a mixture of 2-propanone and methanol, yielding 17 parts of 2-[[1-(phenylmethyl)-4-piperidinyl]-methyl]-1H-benzimidazole; mp. 221.5°-222° C. (compound 1).

Provenance & Evidence