Selenium Dioxide → 3-Chloro-6'-formyl-[2,3]bipyridyl-5-carboxylic acid methyl ester

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Reaction Steps

0.6 g of 3-chloro-6′-methyl-[2,3′]bipyridyl-5-carboxylic acid methyl ester (12) (2.3 mmol) prepared in Example 8 was dissolved in 10 mL of 1,4-dioxane, and 0.75 g of selenium dioxide (6.9 mmol) was added thereto. The mixture was refluxed under heating and stirring for 18 hours, and cooled to room temperature. The mixture was concentrated under reduced pressure, and then dissolved in ethyl acetate to be washed with water. The organic layer was dried over magnesium sulfate, and concentrated under reduced pressure. The residue was separated by column chromatography (eluting solvent: chloroform/methanol=10/1) to obtain 0.51 g of yellow crystal, 3-chloro-6′-formyl-[2,3′]bipyridyl-5-carboxylic acid methyl ester (yield 81%)

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