Copper-Free Sonogashira Coupling of Coumarin Fluorosulfates in Water: A Modified Approach for the Synthesis of Novel Alkynyl Coumarin Derivatives

A modified, atom-economical, and ecofriendly approach developed for synthesizing an array of alkynyl coumarin derivatives by exploring the copper-free Sonogashira coupling reaction is reported herein. The usage of water as a solvent, along with the utilization of coumarin fluorosulfate as an atom-economical electrophilic coupling partner, demonstrates the synthetic utility of this modified methodology. The superiority of coumarin fluorosulfate over other pseudohalide-based leaving groups has been realized by performing a comparative study at a later stage. The environmental friendliness of our modified synthetic protocol has been realized by calculating the E-factor for the formation of products at the final stage.