Ruthenium-Based Catalysts for Aerobic Oxidation of Alcohols

Oxidation reactions continue to play an important role in organic chemistry, and the increasing demand for greener oxidation methods in modern organic synthesis has led to rich developments in the field during recent decades. In order to minimize waste, catalytic methods are one of the most promising solutions, and allow the use of molecular O2 and air as readily available, terminal and ideal oxidants. Ruthenium's versatility is due to the wide range of accessible oxidation states, from −2 to +8, and the different types of oxidation mechanisms that are operative, depending on the ruthenium sources used. In this chapter, the focus is on green oxidation techniques using promising or potentially promising both homogeneous and heterogeneous ruthenium-based catalysts for the aerobic oxidation of alcohols to the corresponding aldehydes and ketones.

A convenient and selective palladium-catalyzed aerobic oxidation of alcohols

An efficient procedure for the oxidation of primary and secondary alcohols to aldehydes and ketones, respectively, with molecular oxygen under ambient conditions has been achieved. By applying catalytic amounts of Pd(OAc)2 in the presence of tertiary phosphine oxides (O=PR3) as ligands, a variety of substrates are selectively oxidized without formation of ester byproducts. Spectroscopic investigations and DFT calculations suggest stabilization of the active palladium(II) catalyst by phosphine oxide ligands.