p-Toluenesulfonic acid → N-(3-formyl-phenyl)pyridine-2-carboxamide

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Reaction Steps

To a solution of pyridine-2-carboxylic acid chlorid (6.5 g) in methylene chloride (75 ml) was added a mixture of triethylamine (6.3 g) and 3-aminobenzaldehyde diethylacetal (9.75 g); (3-aminobenzaldehyde diethylacetal was prepared by reducing (H2, Pd/C, MeHH) 3-nitrobenzaldehyde diethyl acetal, which in turn was made by acetalization of 3-nitrobenzaldehyde with triethylorthoformate and p-toluenesulfonic acid in ethanol). The mixture of the acid chloride and the primary amine was stirred at room temperature overnight, and poured carefully into cold water. The organic layer was separated, dried over anhydrous magnesium sulfate, and then all solvent removed. The residue was dissolved in tetrahydrofuran, and then dilute HCl solution (1N) was added until the acidic mixture remained homogeneous. This mixture was stirred at room temperature for one hour, and then most of the volatile solvent was removed. The aqueous solution was neutralized with NaHCO3, extracted with ethyl acetate, and the organic extract was washed with water and brine. All volatiles were removed, and the residual solid was crystallized from methanol-hexanes to give N-(3-formyl-phenyl)pyridine-2-carboxamide.

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