Highly regio- and stereoselective synthesis of indene derivatives via electrophilic cyclization.

[reaction: see text] Indene or naphthalene derivatives are readily prepared in moderate to excellent yields with high regio- and stereoselectivity under very mild reaction conditions by the reaction of acetylenic malonates and ketones with I2, ICl, or NIS. The resulting iodides can be further elaborated using palladium-catalyzed coupling reactions.