Methyl vinyl ketone → Tert-butyl 9-oxo-3-azaspiro[5.5]undec-7-ene-3-carboxylate

Participants

Reaction Conditions

Reaction Steps

To the solution of tert-butyl 4-formylpiperidine-1-carboxylate (5.87 mmol, 1 eq) in THF (250 ml) was added methyl vinyl ketone (7.63 mmol, 1.3 eq) at 0° C., followed by slow addition of 3 N KOH in ethanol (7.7 ml). The reaction was then stirred at 25° C. for 16 h. The reaction mixture was concentrated to one-third of the volume of solvent and then acidified with 0.5 N HCl at 0° C. The aqueous layer was extracted with ethyl acetate (2×100 ml), and the organics dried over Na2SO4 and concentrated. The crude material was used in the next step without further purification. Yield: 91%

Provenance & Evidence