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This review describes recent progress made in the rapidly developing field of CH bond activation, in particular for syntheses of biaryls. The catalysts presented here provide convenient strategies for the direct arylation of arenes, via single or double CH bond activation, leading to inter-, and intramolecular carbon-carbon bond formation. The literature from mid-2009 to December 2013 has been discussed.

Aromatic enynes can be transformed into arylnaphthalenes or benzofulvenes depending on the reaction conditions. Under gold(I) catalysis, exclusive or major 6-endo-dig cyclization took place leading to arylnaphthalenes. However, a catalytic system based on palladium iodide/1,3-bis(diphenylphosphino)propane, in the presence of cesium carbonate as a base was necessary to furnish exclusively 5-exo-dig cyclization pattern, regardless of the electronic effects of the substituents. In the latter transformation, a mechanistic study (kinetic isotopic effect, density functional theory) involving a CH activation is suggested for the exclusive formation of benzofulvenes.