Ruthenium-Catalyzed [4 + 2] Cycloaddition of Chromanone Dienes Using Triethylamine as an Ethylene Surrogate

A ruthenium-catalyzed [4 + 2] cycloaddition of chromanone diene derivatives using triethylamine (TEA) is described. TEA was employed as an ethylene equivalent, and a bench-stable dinuclear ruthenium complex [Ru(p-cymene)Cl2]2 catalyzed the reaction under mild conditions. This study highlights the utility of TEA as a practical ethylene surrogate and expands the repertoire of ruthenium-catalyzed cycloaddition strategies for the efficient construction of complex molecular architectures.