Ru(II)/PEG-400 as a Highly Efficient and Recyclable Catalytic Media for the Domino Synthesis of 3,4-Disubstituted Isoquinolines and Isocoumarins via C–H Activation

Growing environmental concerns have intensified demand for green and sustainable approaches in chemical synthesis. In response to this need, we have developed an efficient Ru(II)/PEG-400 system as a homogeneous recyclable catalytic medium for the domino synthesis of 3,4-disubstituted isoquinolines and isocoumarins through C–H activation. The use of a biodegradable solvent, simple starting materials, excellent atom economy, and a broad substrate scope enhances the overall efficiency and sustainability of this protocol. Furthermore, the Ru(II)/PEG-400 catalytic medium can be reused over five successive cycles while maintaining its catalytic activity. In the application part, the practicality of this methodology is demonstrated through gram-scale synthesis and photophysical studies of the isoquinoline derivatives.