[Br-].Br[C:3]1[CH:4]=[CH:5][C:6]([C:9]([O:11][CH2:12][CH3:13])=[O:10])=[N:7][CH:8]=1.O.O1[CH2:19][CH2:18][CH2:17]C1>[Cl-].[Zn+2].[Cl-].Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1>[CH:17]1([C:3]2[CH:4]=[CH:5][C:6]([C:9]([O:11][CH2:12][CH3:13])=[O:10])=[N:7][CH:8]=2)[CH2:18][CH2:19]1
A suspension of zinc chloride (27 g) in tetrahydrofuran (300 mL) was cooled to 0° C. in the presence of a nitrogen gas, and a 1 M solution of cyclopropanemagnesium bromide in tetrahydrofuran (186 mL) was added thereto, followed by stirring at room temperature for 30 minutes. The reaction solution was cooled to 0° C. Dichlorobis(triphenylphosphine)-palladium(II) (3.26 g) and a solution of ethyl 5-bromopyridine-2-carboxylate (21.4 g) in tetrahydrofuran (100 mL) were sequentially added, and the mixture was stirred at 0° C. for 30 minutes and at room temperature for one hour. The reaction solution was poured into water, followed by extraction with ethyl acetate. The organic layer was washed with brine, dried over anhydrous magnesium sulfate and filtered. The solvent was then evaporated under reduced pressure. The residue was purified by silica gel column chromatography (hexane:ethyl acetate=4:1→1:1) to give ethyl 5-cyclopropylpyridine-2-carboxylate (15.5 g, 87%) as a pale brown oil.
読み込み中…
