4'-METHOXYVALEROPHENONE

Preparation

To a solution of N-methoxy-Nmethyl- 2-pyridyl urethane (364.4 mg, 2 mmol) in THF (6 mL), p-methoxyphenylmagnesium bromide (0.25 m in THF, 8 mL, 2 mmol) was added dropwise over a period of 10 min at 0 ℃ under nitrogen atmosphere. Stirring was maintained for a further 5 min and then n-butyllithium (1.60 M in hexane, 1.5 mL, 2.4 mmol) was added directly to the mixture (one-pot process). The reaction mixture was stirred for 0.5 h, while warming to room temperature, and was then quenched with 1 N HCl (5 mL). After evaporation of the THF, the concentrated mixture was poured into 1 N HCl (30 mL) and the aqueous phase was extracted with dichloromethane (3×20 mL). The combined organic extracts were dried over MgSO4, filtered, and concentrated to dryness in vacuo. The crude product was purified by column chromatography on silica gel (EtOAc/n-hexane, 1:4) to give 369.1 mg (96%) of p-methoxyvalerophenone.

Preparation

To a solution of N-methoxy-N-methyl-2-pyridyl urethane (364.4 mg, 2 mmol) in THF (6 mL), p-methoxyphenylmagnesium bromide (0.25 m in THF, 8 mL, 2 mmol) was added dropwise over a period of 10 min at 0 °C under nitrogen atmosphere. Stirring was maintained for a further 5 min and then n-butyllithium (1.60 m in hexane, 1.5 mL, 2.4 mmol) was added directly to the mixture (one-pot process). The reaction mixture was stirred for 0.5 h, while warming to room temperature, and was then quenched with 1 n HCl (5 mL). After evaporation of the THF, the concentrated mixture was poured into 1 n HCl (30 mL) and the aqueous phase was extracted with dichloromethane (3*20 mL). The combined organic extracts were dried over MgSO4, filtered, and concentrated to dryness in vacuo. The crude product was purified by column chromatography on silica gel (EtOAc/n-hexane, 1:4) to give 369.1 mg (96%) of p-methoxyvalerophenone.

Synthesis Reference(s)

Chemistry Letters, 15, p. 165, 1986
Tetrahedron, 50, p. 11839, 1994 DOI: 10.1016/S0040-4020(01)89299-1