反应详情

Ethyl magnesium bromide (3.0 M in ether, 2.2 mL, 6.6 mmol) was added dropwise over a period of 1 hour to a solution of ethyl 3-cyanopent-4-enoate (500 mg, 3.27 mmol) and Ti(Oi-Pr)4 (1.1 mL, 3.6 mmol) in diethylether (16.4 mL) at room temperature. The reaction mixture was diluted by the dropwise addition of water (3.27 mL) and stirred at room temperature for an additional 30 minutes. The reaction mixture was filtered and the filtrate was concentrated under reduced pressure to afford the crude product residue. The crude product residue was purified by silica gel chromatography (1:1 ethyl acetate/petroleum ether, Rf=0.3) to afford 7-ethenyl-4-azaspiro[2.4]heptan-5-one as a white solid. MS ESI calc'd. for C8H12NO [M+H]+ 138. found 138. 1H NMR (400 MHz, CDCl3) δ 6.09 (br s, 1H), 5.68-5.60 (m, 1H), 5.08-5.00 (m, 2H), 3.01-2.96 (m, 1H), 2.70-2.64 (m, 1H), 2.40-2.36 (m, 1H), 0.83-0.75 (m, 2H), 0.65-0.58 (m, 2H).

1. filtrationThe reaction mixture was filtered
2. concentrationthe filtrate was concentrated under reduced pressure
3. customto afford the crude product residue
4. customThe crude product residue was purified by silica gel chromatography (1:1 ethyl acetate/petroleum ether, Rf=0.3)