Preparation background and overview of 4-phenylpyridine-N-oxide
4-Phenylpyridine-N-oxide can be used as an intermediate for ammonium bicarbonate in pharmaceutical synthesis. There are many reports in the literature that 4-phenylpyridine-N-oxide can be oxidized using 4-phenylpyridine as the reaction raw material. get later.
Preparation of 4-phenylpyridine-N-oxide
Preparation Report 1 of 4-phenylpyridine-N-oxide,
To a stirred solution of 4-phenylpyridine (5.5-6.7mmol) in CHCl3 (2mL) at 0°C, add 70% m-CPBA (1mol equivalent) in portions ). The resulting mixture was stirred at room temperature for 12h. At this time, complete consumption of the starting material was observed by TLC. The reaction mixture was diluted with CHCl3, and solid K2CO3 was added. (4 molar equivalents), the resulting mixture was stirred for another 10 minutes, the solid was separated by filtration, and the filtrate was dried over Na2SO4 and dried under reduced pressure. Concentration gave 4-phenylpyridine-N-oxide in 86-90% yield.
Preparation Report 2 of 4-phenylpyridine-N-oxide,
Mix H2WO4 (125.0mg, 0.500mmol) and 4-phenylpyridine (1.552g, 10mmol), and stir the mixture at 60°C for 10 minute. After stirring at 60°C for 24 hours, 30% aqueous hydrogen peroxide solution (3.4 mL, 30 mmol) was gradually added dropwise to the mixed solution, and the reaction solution was cooled to room temperature. The yield of 4-phenylpyridine-N-oxide was 90% according to GC and NMR measurements.
Preparation Report 3 of 4-phenylpyridine-N-oxide,
4-Phenylpyridine (5mmol) was added to a solution of UHP (35mmol) in 95% formic acid (12cm3) at room temperature with stirring. The reaction progress was followed by TLC (silica gel, hexane-acetone 4:1). After oxidation is complete (3-12 hours), water (12cm3) is added to the reaction mixture. The aqueous solution was extracted with dichloromethane (3×7cm3), and the organic layer was washed with water (2×7cm3). The combined extracts were then dried over anhydrous Na2SO4, filtered, concentrated in vacuo, and the residue was purified to give pure N-oxide.
References
[1] From Journal of Organic Chemistry, 76(19), 7842-7848; 2011
[2]From Jpn. Kokai Tokkyo Koho, 2005255560, 22 Sep 2005
[3]Fro sodium pyrithione m Synthetic Communications, 30(8), 1529-1534; 2000
