Undirected Hydroarylation and Oxidative Arylation of Olefins

A series of arylations of olefins by C-H bond cleavage without direction by an ortho functional group has also been reported, and these reactions can be divided into two sets. In one case, the C-H bond of an arene adds across an olefin to form an alkylarene product. This reaction has been called hydroarylation. In a second case, oxidative coupling of an arene with an olefin has been reported. This reaction forms an aryl-substituted olefin as product, and has been called an oxidative arylation of olefins. The first reaction forms the same t)q)es of products that are formed from Friedel-Crafts reactions, but with selectivity controlled by the irietal catalyst. For example, the metal-catalyzed process can form products enriched in the isomer resulting from anti-Markovnikov addition, or it could form the products from Markovnikov addition with control of absolute stereochemistry. Examples of hydroarylation and oxidative arylation of olefins are shown in Equations 18.63 - and 18.64.  

Progress on the addition of aromatic C-H bonds to olefins has been made by Periana with iridium catalysts - - and Gunnoe with ruthenium catalysts. - Both systems illustrate that the anti-Markovnikov addition products can be generated in larger quantities than the Markovnikov products, although mixtures of regioisomers are still observed. Intramolecular additions of the C-H bonds of electron-rich heterocycles to electron-deficient alkenes have also been reported (Equation 18.65). Most recently, Tilley has reported the addition of the C-H bond of methane across an olefin catalyzed by scandocene complexes. This reaction occurs, albeit slowly, with Markovnikov regiochemistry. 

The intermolecular oxidative arylation of olefins has been reported in most cases with acrylic acid derivatives. This process could be developed as an alternative to the Heck reaction, which occurs with aryl halides. Several groups have reported versions of this oxidative C-C bond formation. Fujiwara reported intermolecular examples of this reaction catalyzed by palladium and copper (Equation 18.64). Intermolecular versions of this reaction have also been reported with ruthenium catalysts and as the oxidant. Other oxidative reactions in which electron-rich arenes add to olefins (Equation 18.66) have been reported as stoidiiometric steps of natural products syntheses, and later as a catalytic process.  

Functionalization of Alkanes and Arenes with Main Group Reagents 

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