Benzene → Benzyl 9-oxo-3-azaspiro(5.5)undec-7-ene-3-carboxylate

Participants

Reaction Steps

Benzyl 4-formylpiperidine-1-carboxylate (5.17 g, 20.907 mmol) and p-Toluenesulfonic acid monohydrate (0.398 g, 2.091 mmol) were stirred in Benzene (30.0 ml, 334.136 mmol) at 70° C. But-3-en-2-one (3.76 ml, 41.813 mmol) was added and the reaction mixture was refluxed o/n while removing water with dean-stark trap. After cooling the reaction mixture to rt, sat. NaHCO3 soln. was added and the organic layer was dried over Na2SO4 and evaporated. The resulting oil was purified by Biotage (SiO2, 250 g, EtOAc/Hep 10% to 50%) to afford the title compound (3.58 g, 11.96 mmol, 57.2% yield).

Provenance & Evidence