Water → tert-Butyl 3-ethyl-4-oxopiperidine-1-carboxylate

Participants

Reaction Conditions

Reaction Steps

A solution of 4-oxo-piperidine-1-carboxylic acid tert-butyl ester (5 g, 25.1 mmol), pyrollidine (5 ml) and p-toluenesulfonic acid (25 mg) in benzene (100 ml) was heated at reflux for 16 h with azeotropic distillation of water. The resulting enamine solution was cooled to rt and concentrated. The crude enamine was dissolved in acetonitrile (50 ml); iodoethane (4.67 g, 30.1 mmol) was added and the mixture was heated at 100° C. for 0.5 h, cooled to rt and concentrated. The mixture was dissolved in ethyl acetate (200 ml), washed with 1 N hydrochloric acid, saturated aqueous sodium bicarbonate, and brine. The extract was dried over magnesium sulfate, filtered and concentrated. The crude compound was purified by silica gel chromatography (80% hexanes/20% ethyl acetate) to afford 3-ethyl-4-oxo-piperidine-1-carboxylic acid tert-butyl ester (680 mg).

Provenance & Evidence