Selectivity control in thiol–yne click reactions <i>via</i> visible light induced associative electron upconversion
Julia V. Burykina, Nikita S. Shlapakov, Evgeniy G. Gordeev, Burkhard König, Valentine P. Ananikov
Abstract
An associative electron upconversion is proposed as a key step determining the selectivity of thiol-yne coupling. The developed synthetic approach provided an efficient tool to access a comprehensive range of products - four types of vinyl sulfides were prepared in high yields and selectivity. We report practically important transition-metal-free regioselective thiol-yne addition and formation of the demanding Markovnikov-type product by a radical photoredox process. The photochemical process was directly monitored by mass-spectrometry in a specially designed ESI-MS device with green laser excitation in the spray chamber. The proposed reaction mechanism is supported by experiments and DFT calculations.