CYCLOPENTANEACETIC ACID, A,2-DIOXO-, ETHYL ESTER

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 4.0 g (18.2 mmol) of 4-hydrazino-3-trifluoromethylbenzoic acid is dissolved in 20 mL of glacial acetic acid, combined with 3.3 g (18.2 mmol) of ethyl oxo-(2-oxocyclopentyl)acetate, and refluxed for 2 hours under a nitrogen atmosphere. After cooling, it is stirred with diethyl ether and the precipitate is suction filtered. Yield: 2.9 g (43%). refluxed for 2 hours under a nitrogen atmosphere After cooling filtered

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 15.5 mL (0.175 mol) of cyclopentanone and 23.8 mL (0.175 mol) of diethyl oxalate in 90 mL of tetrahydrofuran are added dropwise at 0° C. to a suspension of 7.0 g (0.175 mol) of sodium hydride (50% in oil) in 60 mL of tetrahydrofuran. The mixture is stirred for another 10 minutes at 0° C. and then heated to ambient temperature. After 5 hours, an exothermic reaction sets in and the mixture heats up to 50° C. After 16 hours, it is combined with ice water and extracted with ether. The aqueous phase is adjusted to pH 4 with glacial acetic acid and extracted with ethyl acetate, dried and concentrated by evaporation. The residue is distilled in vacuo. BP(23 mbar)=135° C.-141° C. Yield: 19.6 g (61%). heated to ambient temperature After 5 hours an exothermic reaction sets in and the mixture heats up to 50° C After 16 hours extracted with ether extracted with ethyl acetate dried concentrated by evaporation The residue is distilled in vacuo BP(23 mbar)=135° C.-141° C