GENERAL METHOD: A mixture of aryl ketone (1.0 mmol, here p-hydroxyacetophenone), 1,3-propanediamine (1.3 mmol) and p-toluenesulfonic acid (1.0 mmol) was stirred in THF under oxygen atmosphere. Subsequently Pd(OAc)2 (0.1 mmol) was added and the reaction mixture was heated to reflux temperature and maintained for 8-12 hours. Upon completion of the reaction (monitored by TLC), the reaction mixture was cooled to room temperature and concentrated under reduced pressure. The resulting concentrate was diluted with water and extracted with ethyl acetate. The ethyl acetate layer was washed with Na2S2O3 solution, dried over anhydrous Na2SO4 and subsequently concentrated under reduced pressure to give the crude product. Finally, the target product 2-(4-hydroxyphenyl)pyridine was purified by silica gel column chromatography (eluent: hexane-ethyl acetate mixed solvent).
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