Oxy-sulfonylation of terminal alkynes via C–S coupling enabled by copper photoredox catalysis†
We report the first literature example using visible light-induced trimethylsilyl azide (TMS-N3)-assisted copper-catalyzed oxy-sulfonylation of terminal CC bonds to form β-keto sulfones (C–S bond formation). TMS-N3 promotes the reaction by facilitating the formation of sulfonyl radicals, which later decompose into N2 gas upon light irradiation. This method involves the use of commercially available and stable starting materials. Also, a wide range of functional groups have been well-tolerated under the current photoredox process, evading the side product formation. Potent biologically active compounds, such as CES1, 11β-HSD1 inhibitors, anti-analgesic agents, and reactive synthesis intermediates were synthesized to demonstrate the synthetic utility of the current methodology. Moreover, green chemistry metrics and Eco-scale evaluation for the current photochemical method show that the protocol is eco-friendly and highly efficient.