反应详情

A solution of 4.73 g of 2,6-dibromopyridine in 150 ml of triethylamine is mixed under ice cooling with 2.69 g of pentynoic acid methyl ester, 350 mg of bis-triphenylphosphinepalladium(II) chloride and 48 mg of copper(I) iodide and the mixture is stirred for 1 hour. Then, the ice bath is removed and it is stirred for 3 hours at room temperature. The precipitate--consisting of 2,6-bis-(4-methoxycarbonyl-1-butinyl)-pyridine and triethylammonium bromide--is suctioned off and the filtrate is evaporated to dryness. The residue is chromatographed on silica gel with hexane/ethyl acetate=95/5 to 75/25. 2.32 g of 5-(6-bromo-2-pyridyl)-4-pentynoic acid methyl ester of melting point 59°-61° C. is obtained.

1. customThen, the ice bath is removed
2. stirringit is stirred for 3 hours at room temperature
3. customthe filtrate is evaporated to dryness
4. customThe residue is chromatographed on silica gel with hexane/ethyl acetate=95/5 to 75/25