Photocatalyzed site-selective C(sp3)-H sulfonylation of toluene derivatives and cycloalkanes with inorganic sulfinates

The development of practical methods for the direct and selective C( sp 3 )-H functionalization of hydrocarbons is an attractive topic in synthetic chemistry. Although the radical-mediated hydrogen atom transfer (HAT) process has shown considerable potential in such reactions, it still faces fundamental problems associated with reactivity and selectivity. Herein, we report a convenient and economic approach to site-selective C( sp 3 )-H sulfonylation via photo-induced HAT catalysis. Employing a conjugated polycyclic quinone as a direct HAT photocatalyst, commercially available inorganic sulfinates as the sulfonylation source, copper triflate as an inexpensive oxidant, a variety of toluene derivatives and cycloalkanes were converted into biologically and synthetically interesting sulfone products under mild conditions. The mechanistic studies reveal that the reaction sequence involves direct HAT-induced radical formation and a subsequent copper-mediated organometallic process for the C-S bond formation. This method offers an appealing opportunity to furnish high value-added products from abundant hydrocarbon starting materials and inexpensive reagents. A practical and economic approach to site-selective C( sp 3 )-H sulfonylation of toluene derivatives and cycloalkanes with inorganic sulfonate salts by photo-induced direct hydrogen atom transfer catalysis has been developed. Accordingly, a variety of biologically and synthetically attractive sulfone products have been synthesized in good yields and with high site-selectivity.