Multiple activations of CH bonds in arenes and heteroarenes.

The activation of CH bonds in arenes and heteroarenes has attracted considerable attention in recent years. Examples of the activation of two or more CH bonds in arenes or heteroarenes are rare. In recent studies it has been found that certain polynuclear metal carbonyl complexes, such as Re2(CO)8(μ-C6H5)(μ-H), 1 and Os3(CO)10(NCMe)2, can react two or more times with selected arenes and heteroarenes through a series of CH activations to yield interesting new multiply-CH activated arenes and heteroarenes and can lead to the opening of ring systems in the case of heteroarenes. A summary of these novel reactions and new products is presented in this Frontier article.