Visible Light-Driven and Singlet Oxygen-Mediated Photochemical Cross-Dehydrogenative C<sub>3</sub>–H Sulfenylation of 4-Hydroxycoumarins with Thiols Using Rose Bengal as a Photosensitizer
Goutam Brahmachari, Anindita Bhowmick, Indrajit Karmakar
Abstract
A visible light (white light-emitting diode/direct sunlight)-driven photochemical synthesis of a new series of biologically interesting 3-(alkyl/benzylthio)-4-hydroxy-2H-chromen-2-ones has been achieved through a cross-dehydrogenative C3–H sulfenylation of 4-hydroxycoumarins with thiols at ambient temperature in the presence of rose bengal in acetonitrile under an oxygen atmosphere. The notable features of this newly developed method are mild reaction conditions, energy efficiency, metal-free synthesis, good to excellent yields, use of low-cost materials, and eco-friendliness.
Topics & Concepts
Rose bengalPhotosensitizerSinglet oxygenPhotochemistrySinglet stateChemistryBENGALOxygenExcited stateOrganic chemistryPhysicsBayEngineeringNuclear physicsCivil engineeringSulfur-Based Synthesis TechniquesRadical Photochemical ReactionsCatalytic C–H Functionalization Methods