Catalytic Aerobic Oxidation of C(sp³)−H Bonds

Abstract

Oxidation reactions are a key technology to transform hydrocarbons from petroleum feedstock into chemicals of a higher oxidation state, allowing further chemical transformations. These bulk scale oxidation processes usually employ molecular oxygen as the terminal oxidant as at this scale it is typically the only economically viable oxidant. The produced commodity chemicals possess limited functionality and usually show a high degree of symmetry thereby avoiding selectivity issues. In sharp contrast in the production of fine chemicals preference is still given to classical oxidants. Considering the strive for greener production processes the use of O2, the most abundant and greenest oxidant, is a logical choice. Given the rich functionality and complexity of fine chemicals achieving regio/chemoselectivity is a major challenge. This review presents an overview of the most important catalytic systems recently described for aerobic oxidation, and the current insight in their reaction mechanism.

A Supported Bismuth Halide Perovskite Photocatalyst for Selective Aliphatic and Aromatic C–H Bond Activation

“…In comparison with the partial oxidation of active and expensive alcohol substrates, the direct conversion of hydrocarbons (for example, aliphatic alkanes) in air to commercial oxygenates remains challenging. This is due to the high bond dissociation energy of C(sp 3 )−H bonds (70–130 kcal mol −1 ) and their unfavorable adsorption . The activation of C(sp 3 )−H bonds generally demands specific expensive metal complexes or aggressive oxidants with harsh reaction conditions (high pressure and temperature) .…”

“…Thes elective oxidation of sp 3 CÀHb onds using O 2 to valuable oxygenated products is one of the most important reactions in the chemical industry for fine chemicals and pharmaceuticals production. [1] In comparison with the partial oxidation of active and expensive alcohol substrates, [2] the direct conversion of hydrocarbons (for example,a liphatic alkanes) in air to commercial oxygenates remains challenging. This is due to the high bond dissociation energy of C(sp 3 )ÀH bonds (70-130 kcal mol À1 )a nd their unfavorable adsorption.…”

Efficient Palladium‐Catalyzed Aerobic Arylative Carbocyclization of Enallenynes

“…[2] Over the past decades, palladium-catalyzed aerobic oxidations have provided the basis for streamlined conversion of various feedstocks into valuable products. [7] In spite of the significant synthetic progress offered by these reactions,the relative low catalyst efficiency due to palladium deactivation still remains challenging in most cases. [7] In spite of the significant synthetic progress offered by these reactions,the relative low catalyst efficiency due to palladium deactivation still remains challenging in most cases.…”

Efficient Palladium‐Catalyzed Aerobic Arylative Carbocyclization of Enallenynes

“…[3] Illustrative examples include Wacker oxidations, [4] alcohol oxidations, [5] alkene functionalizations, [6] and oxidative CÀHa ctivations. [7] In spite of the significant synthetic progress offered by these reactions,the relative low catalyst efficiency due to palladium deactivation still remains challenging in most cases. [8] This oxidation problem can be explained by the slow electron transfer directly between Pd 0 and O 2 ,c ompared to the rapid precipitation of palladium black from active palladium species (Scheme 1a).…”