Palladium-catalyzed annulation of arynes by 2-halobenzaldehydes: synthesis of fluoren-9-ones.

Arynes, generated in situ from 2-(trimethylsilyl)aryl triflates and CsF, undergo annulation by o-haloarenecarboxaldehydes in the presence of a Pd catalyst, providing a useful new method for the synthesis of fluoren-9-ones in good yields. [reaction: see text]