Azobisisobutyronitrile → (E)-Ethyl 4-bromo-3-(1-ethoxycarbonylcyclopropyl)-2-fluoro-2-butenoate

Participants

Reaction Steps

To a solution of ethyl 3-(1-ethoxycarbonylcyclopropyl)-2-fluoro-2-butenoate (152.78 g, 0.625 mol) in chloroform (1500 ml) were added N-bromosuccinimide (111.33 g, 0.625 mol) and a catalytic amount of 2,2'-azobis-(isobutyronitrile) and then the resultant mixture was heated under reflux for 16 hours. Then, the liquid reaction mixture was cooled and concentrated under reduced pressure. After adding benzene (300 ml), insoluble matter was filtered off and the filtrate was concentrated under reduced pressure. The residue was subjected to flash silica gel column chromatography (eluent:n-hexane:ethyl acetate=4:1) to obtain 100.5 g (49.7%) of the title compound as a yellow oily substance. On the other hand, 75 g (37.1%) of (Z)-ethyl 4-bromo-3-(1-ethoxycarbonylcyclopropyl)-2-fluoro-2-butenoate (the geometrical isomer of the title compound) was obtained as a yellow oily substance with the use of another eluent (n-hexane:ethyl acetate=2:1).

Provenance & Evidence