Reaction #927281

Reaction equation

5-amino-2-[2-(4-cyanophenyl)-ethyl]-1-methyl-benzimidazole

NaOH

AcOH

4-dimethylamino-benzaldehyde

→

2-[2-(4-Cyanophenyl)-ethyl]-1-methyl-5-(4-dimethylaminobenzylamino)-benzimidazole

Solvents

CH2Cl2

water

Conditions

Workup

1. 1
   workup.STIRRINGThe mixture is stirred for 1 h at ambient temperature
2. 2
   OtherThe organic phase is separated off
3. 3
   Otherdried
4. 4
   Concentrationconcentrated by evaporation
5. 5
   OtherThe product is chromatographed over silica gel (CH2Cl2/methanol=5/1)
6. 6
   Othercrystallised from ethyl acetate

Procedure

5-amino-2-[2-(4-cyanophenyl)-ethyl]-1-methyl-benzimidazole (1.0 g, 3.6 mmol) which is obtainable according to Example 2 (step c) and 4-dimethylamino-benzaldehyde (0.59 g, 3.0 mmol) in 25 mL of CH2Cl2 with 0.22 mL of AcOH are combined with Na[HB(OAc)3](2.2 g, 10.3 mmol) at ambient temperature with stirring. The mixture is stirred for 1 h at ambient temperature, covered with water, carefully acidified with conc hydrochloric acidaq and then made alkaline with 4N NaOH solution. The organic phase is separated off, dried and concentrated by evaporation. The product is chromatographed over silica gel (CH2Cl2/methanol=5/1) and crystallised from ethyl acetate.

Source