2-Bromo-4-methylpyridine → 2-(4-Methylpyridin-2-yl)but-3-yn-2-ol

Participants

Reaction Conditions

Reaction Steps

This compound was prepared according to a procedure similar to that described in Procedure C. Into a 250-mL 3-necked round-bottom flask purged and maintained with an inert atmosphere of nitrogen, was placed a solution of 2-bromo-4-methylpyridine (8.5 g, 49.41 mmol, 1.00 equiv) in tetrahydrofuran (110 mL). This was followed by the addition of n-BuLi (22 mL, 1.20 equiv) dropwise with stirring at −78° C. The resulting solution was stirred for 30 min at −78° C. To this was added 4-(trimethylsilyl)but-3-yn-2-one (7.6 g, 54.19 mmol, 1.10 equiv) dropwise with stirring at −78° C. The resulting solution was warmed slowly to 0° C. and stirred for 10 min at this temperature. The reaction was then quenched by the addition of 10 mL of sat. aq. ammonium chloride. The resulting solution was extracted with 2×40 mL of ethyl acetate and the organic layers combined and dried over sodium sulfate and concentrated under vacuum. The residue was applied onto a silica gel column with petroleum ether:ethyl acetate (5:1). This resulted in 6.5 g (56%) of 2-(4-methylpyridin-2-yl)-4-(trimethylsilyl)but-3-yn-2-ol as colourless oil. Into a 250-mL round-bottom flask, was placed a suspension of 2-(4-methylpyridin-2-yl)-4-(trimethylsilyl)but-3-yn-2-ol (6.5 g, 27.85 mmol, 1.00 equiv) and potassium fluoride dihydrate (6.6 g, 2.50 equiv) in methanol (50 mL). The resulting solution was stirred for 4 h at 50° C. The resulting mixture was concentrated under vacuum. The resulting solution was diluted with 100 mL of ethyl acetate. The resulting mixture was washed with 2×50 mL of brine. 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 (1:5). This resulted in 3.5 g (78%) of 2-(4-methylpyridin-2-yl)but-3-yn-2-ol as a pink solid.

Provenance & Evidence