Molecular oxygen as a green, inexpensive oxidant and oxygen source has displayed lots of advantages compared to other oxidants. This review introduces the recent advances of radical processes in molecular oxygen-mediated oxygenation reactions.

An efficient intermolecular atom-transfer addition reaction of alkynes via the combination of visible-light photoredox catalysis and gold catalysis has been developed, affording diverse trifluoromethylthio- and difluoromethylthio-functionalized vinylsulfones with high stereoselectivity in good yields. Thiosulfonylation reaction of enyne can also be realized for constructing functionalized carbo- and heterocycles through a radical cascade cyclization process. These reactions proceed through a gold-assisted sulfonyl radical addition pathway.

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Trifluoromethanesulfonic anhydride has been widely used in synthetic organic chemistry, not only for the conversion of various oxygen-containing compounds to the triflates, but also for the electrophilic activation and further conversion of amides, sulfoxides, and phosphorus oxides. In recent years, the utilization of Tf 2 O as an activator for nitrogen-containing heterocycles, nitriles and nitro groups has become a promising tool for the development of new valuable methods with considerable success. In addition, Tf 2 O has been used as an efficient radical trifluoromethylation and trifluoromethylthiolation reagent due to the contained SO 2 CF 3 fragment, and significant progress has been made in this area. This review summarizes the recent progress in the applications of Tf 2 O in the above two aspects, and aims to illustrate the role and potential application of this reagent in organic synthesis.