Oxalic Acid → HCID 20548860, compound

Participants

Reaction Steps

15.0 g (0.045 mol) of the trans-3-hydroxy-4-phenoxy-1-carbobenzyloxy-piperidine described in Example 14 are dissolved, together with 28.34 g (0.13 mol) of dicyclolohexylcarbodiimide and 3.7 ml (0.045 mol) of pyridine, in 80 ml of dry dimethylsulphoxide. The mixture is cooled to 0° with an ice-water bath and treated with 2.6 g (0.023 mol) of trifluoroacetic acid. The cooling bath is removed again and the reaction mixture is stirred for a further 4 hours at room temperature in a nitrogen atmosphere. The white suspension is diluted with 250 ml of ethyl acetate and treated dropwise with a solution of 12.3 g (0.13 mol) of oxalic acid in 200 ml of methanol. After the evolution of gas has ceased, the reaction mixture is cooled to 0° in an ice-water bath and diluted with 400 ml of water and the dicyclohexylurea which has precipitated is separated off. The aqueous phase of the filtrate is extracted with 250 ml of ethyl acetate and the combined organic phases are dried over sodium sulphate and evaporated to dryness under a water pump vacuum. The resulting crude product is dissolved in benzene and the solution is filtered through a layer of silica gel. 4-Phenoxy-1-carbobenzyloxy-3-piperidone is obtained in the form of a pale yellow oil by elution with a benzene/ethyl acetate mixture (95:5).

Provenance & Evidence