Acetic Acid → TERT-BUTYL 4-(1-CYANO-2-ETHOXY-2-OXOETHYLIDENE)PIPERIDINE-1-CARBOXYLATE

Participants

Reaction Steps

A mixture of tert-butyl 4-oxo-1-piperidinecarboxylate (25.25 g, 127 mmol), ethyl cyanoacetate (13.8 ml, 130 mmol), ammonium acetate (2.73 g, 35.4 mmol), glacial acetic acid (6.3 ml) and benzene (250 ml) was heated for 4 hours at reflux under Dean Stark conditions. The reaction mixture was cooled to room temperature and washed successively with water, sodium bicarbonate solution and brine. Drying, filtration and evaporation of the organic phase provided tert-butyl 4-(1-cyano-2-ethoxy-2-oxoethylidene)piperidine-1-carboxylate as an oil that crystallized on standing (37 g, 99%). 1H NMR (400 MHz, CDCl3): δ 4.28 (q, 2H, J=7 Hz), 3.60 (br t, 2H, J=6 Hz), 3.54 (br t, 2H, J=6 Hz), 3.12 (t, 2H, J=6 Hz), 2.76 (t, 2H, J=6 Hz), 1.47 (s, 9H), and 1.35 (t, 3H, J=7 Hz). ES-LCMS m/z 293 (M−1).

Provenance & Evidence