alpha-Fluorostyrenes synthesized from substituted styrenes by a two-st
ep bromofluorination-dehydrobromination procedure and the E/Z-isomers
of beta-fluorostyrene do react in thermal [4+2]-cycloadditions with th
e super diene 1,3-diphenylisobenzofuran. alpha-Fluorostyrenes are less
reactive and the endo/exo ratio is decreased in all cases compared to
the parent olefins. Both electron donating and electron withdrawing s
ubstituents in the aromatic ring of alpha-fluorostyrenes accelerate th
e reaction rate, suggesting a neutral Diels-Alder reaction. Copyright
(C) 1996 Published by Elsevier Science Ltd