Hydrochloric Acid → rel-(3R,5S)-3,5-Dimethyl-1-(phenylmethyl)-4-piperidinone

Participants

Reaction Conditions

Reaction Steps

A mixture of the crude dimethyl 1-benzyl-3,5-dimethyl-4-oxopiperidine-3,5-dicarboxylate (786.0 g, ca. 2.3 mol) and 1M hydrochloric acid solution (11.5 L) was refluxed for 24 hours. The reaction mixture was cooled to 10° C. and 25% wt. aqueous sodium hydroxide solution (1.92 kg) was added slowly. The mixture was extracted with dichloromethane (4×4 L), and the combined organic extracts concentrated to dryness to give the crude (3R,5S)-1-benzyl-3,5-dimethylpiperidin-4-one (475 g) as a light brown oil. The 1H NMR indicated that it was a 6:1 desired: undesired diastereomeric mixture.

Provenance & Evidence