The inertness of C-H bonds of alkanes is a fundamental problem in organic synthesis. One of few ways of functionalization of alkanes is a free radical activation of C-H bonds using nitrogen- and oxygen-centered radicals, as well as halogen atoms. S-centered radicals have not previously been used for this purpose due to their increased stability and, as a consequence, the thermodynamic unfavourableness of their reaction with alkanes.
Researchers from laboratory № 8 ZIOC RAS under the guidance of Prof. Dr. A.D. Dilman succeeded in "overcoming" this fundamental limitation by using fluorinated disulfide as an alkane activator and a radical trap at the same time. Direct thiolation of unactivated C - H bonds of alkanes became possible due to the extreme electrophilicity of the fluorinated substituent at the sulfur atom, which dramatically changes the energy profile of the reaction. In most cases, the reaction proceeds with high yields upon visible light irradiation without the use of compounds of transition metals.
L. I. Panferova, M. O. Zubkov, V. A. Kokorekin, V. V. Levin, A. D. Dilman, Using the Thiyl Radical for Aliphatic Hydrogen-Atom Transfer: Thiolation of Unactivated C-H Bonds Angew. Chem. Int. Ed., 2021, in press, DOI: 10.1002/anie.202011400