Diethyl Ether → 2-(2-Phenylethynyl)pyridine

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Reaction Steps

2-Phenylpyrazolo[1,5-a]pyridine was prepared by the following procedure. A solution of 2-(phenylethynyl)pyridine (3.2 g, 0.018 mol) in dichloromethane (20 mL) was cooled to 0° C. in an ice bath. A solution of O-mesitylenesulfonylhydroxylamine in dichloromethane was added dropwise, keeping the temperature below 5° C. The mixture was stirred for 30 minutes, then ethyl ether was added to precipitate a solid (5–7 g). The solid was filtered off, washed with ethyl ether and dried. The solid was re-dissolved in DMF and solid K2CO3 (4.5 g, 0.033 mol) was added in small portions. After stirring 2 h, water (100 mL) was added to the mixture, followed by extraction with dichloromethane. The organics were dried over magnesium sulfate, filtered, and evaporated to an orange oil (2.3 g). Chromatography on silica with dichloromethane eluent yielded the 2-(phenylethynyl)pyridine in 83% yield, mp 110° C. 1H NMR and mass spectra analysis confirmed the structure.

Provenance & Evidence