Potassium Carbonate → 2-(5-Chloropyridin-2-yl)but-3-yn-2-ol

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Reaction Steps

This compound was prepared according to a procedure similar to that described in Procedure C. to a 100-mL 3-necked round-bottom flask, s-BuLi (1.3M in hexane, 10 mL) was added into a solution of 2-bromo-5-chloropyridine (1.92 g, 9.98 mmol, 1.00 equiv) in ethyl ether (20 mL) under −76° C., Stirred for 1 h at this temp., 4-(trimethylsilyl)but-3-yn-2-one (1.54 g, 10.98 mmol, 1.10 equiv) was added. The resulting solution was stirred for 2 h at −76° C. The reaction was then quenched by the addition of 10 mL of ammonium chloride (sat., aq.). The resulting solution was extracted with 3×20 mL of ethyl acetate and the organic layers combined. The resulting mixture was washed with 1×20 mL of brine. The solid was dried in an oven under reduced pressure. This resulted in 2.5 g (crude) of 1-(5-chloropyridin-2-yl)-3-(trimethylsilyl)prop-2-yn-1-one as brown oil. In a 50-mL round-bottom flask, potassium carbonate (2.8 g, 20.29 mmol, 2.06 equiv) was added batchwise into a solution of 2-(5-chloropyridin-2-yl)-4-(trimethylsilyl)but-3-yn-2-ol (2.5 g, 9.85 mmol, 1.00 equiv) in methanol (25 mL). The resulting solution was stirred for 2 h at room temperature. TLC indicated the reaction completed, the solvent was concentrated under vacuum. The residue was diluted with 20 mL of water. The resulting solution was extracted with 3×20 mL of ethyl acetate and the organic layers combined. The resulting mixture was washed with 1×20 mL of brine. The solids were filtered out. The mixture was dried over anhydrous sodium sulfate and concentrated under vacuum, the residue was applied onto a silica gel column with ethyl acetate/petroleum ether (1:10). This resulted in 800 mg (45%) of 2-(5-chloropyridin-2-yl)but-3-yn-2-ol as brown oil.

Provenance & Evidence