Reaction #5338

Reaction equation

crude crystals

Methyl 2-ethoxy-1-[[2'-(ethoxycarbonyloxy-carbamimidoyl)biphenyl-4-yl]methyl]benzimidazole-7-carboxylate

1,8-diazabicyclo[5.4.0]undec-7-ene

→

title compound

Yield 57.6%

Methyl 2-ethoxy-1-[[2'-(2,5-dihydro-5-oxo-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]methyl]benzimidazole-7-carboxylate

Yield 57.6%

Solvents

ethyl acetate

Conditions

Workup

1. 1
   OtherThe reaction mixture was partitioned between ethyl acetate (50 ml) and 1N HCl (20 ml)
2. 2
   WashThe organic layer was washed with water
3. 3
   Otherdried
4. 4
   Concentrationconcentrated to dryness
5. 5
   OtherThe residue was crystallized from chloroformethyl acetate

Procedure

The crude crystals (4.0 g) obtained in Example (57b) was dissolved in ethyl acetate (50 ml). To the solution was added 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU, 3.2 g), and the mixture was stirred for 2 hours at 80° C. The reaction mixture was partitioned between ethyl acetate (50 ml) and 1N HCl (20 ml). The organic layer was washed with water, dried and concentrated to dryness. The residue was crystallized from chloroformethyl acetate to afford the title compound as colorless prisms (2.1 g, 45%), which was in agreement with that obtained in Example (1d).

Source