The palladium-catalyzed annulation of arynes by substituted o-halostyrenes produces substituted 9-fluorenylidenes in good yields. This methodology provides this important carbocyclic ring system in a single step, which involves the generation of two new carbon-carbon bonds, occurs under relatively mild reaction conditions, and tolerates a variety of functional groups, including cyano, ester, aldehyde, and ketone groups.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2731569PMC
http://dx.doi.org/10.1021/ol900554rDOI Listing

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