反应详情

A solution of 2a (4.38 g, 0.031 mol), NBS (5.8 g, 0.033 mol) and 100 mg of AIBN in 40 mL of carbon tetrachloride was heated at 70° C. for 16 h. Cooled to rt and the precipitate was filtered. The solvent was concentrated in vacuo to an oil that was subjected to flash chromatography (5% ethyl acetate/95% hexanes) to give 4.95 g (72%) of the desired product 3a. 1H NMR (CDCl3) δ 7.8 (s, 1H), 4.8 (s, 2H), 2.8 (s, 3H).

1. filtrationthe precipitate was filtered
2. concentrationThe solvent was concentrated in vacuo to an oil that