反应详情

温度

-78 °C

To a solution of diazomethane (nominally 0.68 g—generated from DIAZALD® (5 g) in diethyl ether (45 ml)) at −78° C. was added a solution of E/Z methyl-2-bromo-2-butenoate (3.58 g) (available from Fluka) in diethyl ether (15 ml), dropwise, over 15 min. The mixture was maintained at −78° C. for 1 h then allowed to warm to 20° C. with stirring overnight. Acetic acid (1 ml) was added to destroy excess diazomethane and the mixture evaporated under reduced pressure. The residue was co-evaporated with toluene. Purification of the residue by column chromatography on silica gel eluting with ethyl acetate:cyclohexane (1:1) gave the title compound (1.12 g) as an orange solid.

1. customat −78° C.
2. temperatureto warm to 20° C.
3. customto destroy excess diazomethane
4. customthe mixture evaporated under reduced pressure
5. customPurification of the residue by column chromatography on silica gel eluting with ethyl acetate:cyclohexane (1:1)