Alkane Functionalization via Electrophilic Activation

Electrophilic activation, which may be defined as the substitution of a transition metal center for a proton to generate a new metal–carbon bond, is the basis of a number of promising approaches to selective catalytic functionalization of alkanes. The field was introduced by the groundbreaking chemistry exhibited by aqueous chloroplatinum complexes, reported by Shilov in the early 1970s. Since then the field has expanded greatly, and electrophilic alkane activation has been demonstrated using a wide variety of species. These include ligand-supported platinum complexes; complexes of additional late transition metals, most commonly palladium but also iridium, gold and others; and even post-transition metals such as mercury. That body of work is surveyed here, with particular emphasis on mechanistic understanding, examples of actual functionalization at sp^3-hybridized C–H bonds in alkanes and related compounds, and assessment of the further development that will be needed for practical applications.