Visible-light mediated three-component sulfonylative annulation Ganesh Chandra Upreti, Tavinder Singh, Sudhir Ranjan, Raju Kumar Gupta, Anand Singh Indian Institute of Technology Kanpur, India Sulfones are the privileged structural motifs that are found in various types of pharmaceuticals, agrochemicals, and synthetic intermediates 1 hence the insertion of SO 2 into any skeleton is always demanding for the synthetic community. Traditionally sulfonylation required sulfonyl hydrazides, sulfinic acid or their salts, and sulfonylated oxamic acids 2-4 . All these methods suffer from harsh oxidizing condition. Herein we have reported metal-free visible light-mediated three-component sulfonylative annulation in a single operation. This strategy provides a mild condition for the synthesis of sulfonated benzimidazo/indolo isoquinolin-one. Aryl diazonium salts are readily available aryl surrogates and Na 2 S 2 O 5 is an inexpensive SO 2 surrogate making it a valuable multicomponent transformation 5 . References 1. Wang, M.; Jiang, X., Sulfur–Sulfur Bond Construction. Topics in Current Chemistry 2018, 376 (2), 14. 2. Tang, Y.; Yang, M.; Wang, F.; Hu, X.; Wang, G., Synthesis of sulfonylated benzimidazo[2,1-a]isoquinolin-6(5H)-ones via I2O5-induced radical relay addition/cyclization of activated alkenes with sulfonylhydrazides. Tetrahedron Letters 2021, 67 , 152845. 3. Shen, Z.-J.; Huang, B.; Ma, N.; Yao, L.; Yang, C.; Guo, L.; Xia, W., Transition Metal-Free Synthesis of Sulfonyl- and Bromo- Substituted Indolo[2,1-α]isoquinoline Derivatives through Electrochemical Radical Cascade Cyclization. Advanced Synthesis & Catalysis 2021, 363 (7), 1944-1954. 4. Liu, Q.; Wang, L.; Liu, J.; Ruan, S.; Li, P., Facile synthesis of carbamoylated benzimidazo[2,1-a]isoquinolin-6(5H)-ones via radical cascade cyclization under metal-free conditions. Organic & Biomolecular Chemistry 2021, 19 (15), 3489-3496. 5. Upreti, G. C.; Singh, T.; Ranjan, S.; Gupta, R. K.; Singh, A., Visible-Light-Mediated Three-Component Cascade Sulfonylative Annulation. ACS Omega 2022, 7 (34), 29728-29733.
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