A Practical and Scalable Synthesis of Cyclized and Uncyclized Xanthene‐1,8‐Dione Derivatives Using Cyanuric Chloride as a Green Organocatalyst

A mild, water‐mediated protocol has been developed for the synthesis of both uncyclized and cyclized 1,8‐dioxo‐octahydroxanthene derivatives under ambient conditions. Utilizing cyclic‐1,3‐dicarbonyl compounds and structurally diverse aromatic or heteroaromatic aldehydes, the transformation proceeds efficiently with cyanuric chloride (TCT) as a green organocatalyst. The reaction conditions are finely tunable, allowing selective access to either uncyclized intermediates or cyclized products by adjusting time and temperature, thereby enabling modular control over product outcomes. The protocol also demonstrates excellent compatibility with isatin derivatives, yielding spirooxindolo xanthenedione frameworks in high yields. Substrate scope evaluation revealed broad functional group tolerance, with several products displaying notable biological activities, including anticancer, antibacterial, and antileishmanial properties. All synthesized compounds are fully characterized using spectroscopic techniques such as 1 H, 13 C, and mass spectroscopy. A detailed, plausible mechanism for the transformation has also been proposed and discussed. Comprehensive green metrics, including atom economy, E‐factor, process mass intensity, and other metrics, are calculated for each cyclized derivative. Gram‐scale experiments further confirmed the scalability and environmental sustainability of this operationally simple, metal‐free, and energy‐efficient protocol.