Reaction #82989

Reaction equation

3-Benzyl-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylic acid

p-toluenesulfonic acid monohydrate

sodium carbonate

→

ethyl 3-benzyl-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylate

Solvents

ethanol

Conditions

Workup

1. 1
   Temperatureheating the mixture
2. 2
   Temperatureunder reflux for 8 hours
3. 3
   Concentrationconcentrating the mixture under reduced pressure
4. 4
   workup.ADDITIONadding a saturated aqueous sodium bicarbonate to the reaction residue
5. 5
   Extractionextracting it with ethyl acetate
6. 6
   Washwashing the extraction solution successively with water and saturated aqueous NaCl solution
7. 7
   Dryingdrying it over anhydrous magnesium sulfate
8. 8
   Concentrationconcentrating the resulting solution

Procedure

3-Benzyl-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylic acid (1.50 g, 6.13 mmol) was suspended in ethanol (30 ml), followed by adding p-toluenesulfonic acid monohydrate (145 mg, 0.76 mmol), heating the mixture under reflux for 8 hours, adding sodium carbonate to the reaction solution for neutralization, concentrating the mixture under reduced pressure, adding a saturated aqueous sodium bicarbonate to the reaction residue, extracting it with ethyl acetate, washing the extraction solution successively with water and saturated aqueous NaCl solution, drying it over anhydrous magnesium sulfate, concentrating the resulting solution to obtain ethyl 3-benzyl-2,4-dioxo-3-azabicyclo[3.1.0]hexane-6-carboxylate (1.51 g, 5.52 mmol, 90%), and recrystallizing it from ethanol to obtain a pure product.

Source