3-Pyridinecarboxaldehyde → Pyridine, 3-(2,2-dibromoethenyl)-

Beteiligte Stoffe

Reaktionsschritte

Tetrabromomethane (24.82 g, 0.747 mole) and triphenylphosphine (39.17 g, 0.149 mole) were stirred together in dry methylene chloride (100 mL) for 5 min. at 0° C. under a nitrogen atmosphere. To this mixture was added dropwise pyridine 3carboxaldehyde (4 g, 0.0373 mole). The solution was then stirred for 45 min. at ambient temperature. The reaction mixture was extracted with aqueous 6N hydrochloric acid (3×25 mL), the aqueous layer basified with solid sodium bicarbonate to pH 8-9 and extracted with chloroform (4×25 mL). The combined organic liquours were dried over anhydrous sodium sulfate, filtered and concentrated on a rotary evaporator to give a dark colored syrup. The crude product was chromatographed on silica gel (70-230 mesh) with chloroform:methanol (95:5) as eluant, to afford a light yellow solid (5.0 g, 70%) which rapidly turned dark on standing.

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