Iron-Promoted Cyclization/Halogenation of Alkynyl Diethyl Acetals

Abstract

FeCl(3)- and FeBr(3)-promoted cyclization/halogenation of alkynyl diethyl acetals has been efficiently realized, selectively affording (E)-2-(1-halobenzylidene or alkylidene)-substituted five-membered carbo- and heterocycles which were then efficiently transformed to vinylarenes by Suzuki coupling. The present protocol has provided a new alternative route to vinylic C-Cl and C-Br bond formation.