Heck reaction with an alkenylidenecyclopropane: the formation of arylallylidenecyclopropanes

The palladium–tetraphosphine catalyzed arylation of an alkylidenecyclopropane gives a simple and direct access to 1-aryl-2-methyl-1-(2,2,3,3-tetramethylcyclopropylidene)propenes. This reaction tolerates several functional groups on the aryl bromides. Even heteroaryl bromides have been used successfully. This reaction probably proceeds via a classical oxidative addition of the aryl bromide to palladium, insertion of the CCMe2 bond in the Ar–Pd bond followed by β-elimination to give the dienes.