Reaction #302877

Reaction equation

2-aminobenzimidazole

ethyl acrylate

→

3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one

Yield 54.7%

Conditions

Workup

1. 1
   Temperatureto cool down to room temperature
2. 2
   workup.WAITUpon standing over night
3. 3
   Other3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one crystallized from the medium
4. 4
   Otherwas isolated by filtration
5. 5
   Other3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one was recrystallized from 1-methoxy-2-propanol

Procedure

5.32 g (40 mmol) 2-aminobenzimidazole and 4.00 (40 mmol) ethyl acrylate were dissolved in 25 ml Proglyde DMM. The reaction mixture was heated to 130° C. and the reaction was allowed to continue for 6 hours at 130° C. The reaction mixture was allowed to cool down to room temperature. Upon standing over night, 3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one crystallized from the medium and was isolated by filtration. 3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one was recrystallized from 1-methoxy-2-propanol. 4.1 g (54.7%) 3,4-dihydro-pyrimidino[1,2-a]benzimidazol-2(1H)-one was isolated (m.p. >260° C.).

Source