A convenient method for the preparation of synthetically useful 3-
iodoindene derivatives has been developed. This protocol, based on the 5-endo
iodocyclization reaction of o-(alkynyl)styrenes, represents one of the scarce examples of
halocyclizations using olefins as nucleophilic counterparts and allows the synthesis of both
3-iodo-1H-indenes (from β-alkyl-β-alkyl/aryl-o-(alkynyl)styrenes) and 3-iodobenzofulvenes
(from β,β-diaryl-o-(alkynyl)styrenes) in good yields under mild reaction conditions.
In addition, related alkoxyiodocyclization processes are described, which are particularly
interesting in their intramolecular version because they allow the synthesis of
heteropolycyclic structures containing the indene core. Finally, the usefulness of the
prepared 3-iodoindenes has been demonstrated by the synthesis of several polysubstituted
indene derivatives through conventional palladium-catalyzed cross-coupling reactions and
iodine−lithium exchange processes.
