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A palladium-catalyzed, norbornene-mediated ortho-alkylation reaction of aryl iodides with secondary alkyl halides is described. Intermolecular or intramolecular ortho-alkylation proceeds in a domino process with various termination steps, generating two new carbon-carbon or carbon-nitrogen bonds in one pot, to afford an array of polycyclic heterocycles. The use of enantioenriched substrates has shown that this palladium-catalyzed reaction is stereospecific, proceeding with minimal erosion of ee.

The stereoselective synthesis of both cis- and trans-β-fluorostyrene derivatives from a common intermediate, (Z)-1-aryl-2-fluoro-1-(trimethylsilyl)ethenes, is described. The trans isomers are obtained by a stereospecific replacement of the silyl group in the presence of water and a fluoride source, whereas the preparation of the cis isomers is achieved by a bromination/desilicobromination sequence followed by reduction of the newly created C-Br bond. A stereoselective transformation of both stereoisomers of β-fluorostyrene is also presented.

A palladium-catalyzed domino ortho-alkylation/alkenylation forming up to three new C-C bonds furnishes functionalized tetrahydroisoquinolines in up to 87% yield. Extension to the formation of tetrahydrobenzoazepines and tetrahydroisoquinolinones is presented.

We report a new synthetic sequence for the preparation of silylated 2,2-difluorostyrene derivatives. This new route has numerous advantages over the previous one including enhanced scope, higher yields, ease of purification, and significant reduction of the amount of desilylated side-products. An unexpected transformation of a silylated 2,2-difluorostyrene derivative is also presented.

Review: preparation and applications as fluorinating and activating agents; 29 refs.

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