4-Acetylpyridine → 4-Acetylpyridine-N-oxide

Participants

Reaction Steps

In a manner analogous to the preparation of the compound of Example 1, from 3,4,5-trimethoxyphenylguanidine nitrate (2.25 g, 7.81 mmol), 3-dimethylamino-1-(1-oxo-pyrid-4-yl)-2-propen-1-one (880 mg, 7.81 mmol) and sodium hydroxide (344 mg, 8.6 mmol) to give the title compound (1.2 g) as a green solid m.p. 220°. MS m/z 355 (M+H). The 3-dimethylamino-1-(1-oxopyrid-4-yl)-2-propen-1-one used as starting material was prepared by heating a solution of 4-acetylpyridine-N-oxide (2.5 g, 18.2 mmol) in dimethylformamide diethylacetal (30 ml) at reflux for 0.5 h. On cooling the resulting solid was collected and washed with diethyl ether to give the desired product (3.18 g) as an orange solid m.p. 181°. The 4-acetylpyridine-N-oxide was prepared by treating a solution of 4-acetylpyridine (3.0 g, 24.8 mmol) in CH2Cl2 with 3-chloro-peroxybenzoic acid [Aldrich 57-86%] (8.4 g) at room temperature for 12 h. The reaction was filtered, the filtrate concentrated under reduced pressure and the resulting residue subjected to column chromatography [silica 10% methanol-ethyl acetate] to give the desired product (3.2 g) as a white solid m.p. 101°.

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