methyl 2-(4-fluorophenyl)-1-oxidopyridin-1-ium-3-carboxylate

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 2-(4-fluorophenyl)-3-(methoxycarbonyl)pyridine-1-oxide (10.5 g.) in acetic anhydride (500 ml.) was stirred at reflux for 17 hr., cooled, evaporated to dryness and the residue partitioned between saturated sodium bicarbonate solution and ethyl acetate. The organic layer was separated, dried and evaporated to dryness. The gum obtained was dissolved in methanol (400 ml.), treated with a solution of potassium carbonate (11.7 g.) in water (100 ml) and stirred at ambient temperature for 2 hours. The methanol was evaporated off, the aqueous residue diluted with more water (200 ml.) and the mixture filtered to give methyl 2-(4-fluorophenyl)-6-hydroxypyridin-3-carboxylate (8.0 g.) as a brown solid. at reflux for 17 hr , cooled evaporated to dryness the residue partitioned between saturated sodium bicarbonate solution and ethyl acetate The organic layer was separated dried evaporated to dryness The gum obtained The methanol was evaporated off the aqueous residue diluted with more water (200 ml.) the mixture filtered

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of methyl 2-(4-fluorophenyl)pyridin-3-carboxylate (10.5 g.) and MCPBA (12.33 g., 65%) in dichloromethane was stirred at 0° C. for 1 hour and then at ambient temperature for 2 hours. It was then washed with saturated sodium bicarbonate solution (300 ml.), dried and applied directly to a silica flash column which was eluted firstly with ethyl acetate/iso-hexane (1:1), ethyl acetate and ethyl acetate/methanol (9:1) to give 2-(4-fluorophenyl)-3-(methoxycarbonyl)pyridine-1-oxide as a white solid (10.5 g.). at ambient temperature for 2 hours It was then washed with saturated sodium bicarbonate solution (300 ml.) dried was eluted firstly with ethyl acetate/iso-hexane (1:1), ethyl acetate and ethyl acetate/methanol (9:1)