436. Immobilized Rose Bengal as Photocatalyst for Metal-Free Thiocyanation of Azaheterocycles under Continuous Flow Conditions

Sergio Rossi, Eleonora Colombo, Monica Fiorenza Boselli, Laura Raimondi and Alessandra Puglisi, Helvetica Chimica Acta (2023), DOI: 10.1002/hlca.202300132 (open access)

The immobilization of Rose Bengal onto Merrifield resin and its application in the light-driven metal-free thiocyanation of azaheterocycles in continuo were investigated. The supported photocatalyst was used in batch reactions under heterogeneous conditions, with different azaheterocycles, and proved to efficiently promote the reaction. The resin-supported Rose Bengal was then employed under continuous flow conditions, affording thiocyanate functionalized azaheterocycles with higher space-time-yields than the in-batch transformations, and in a shorter reaction time. The easily modification of the SCN groups was also demonstrated by synthetizing trifluoromethyl thioethers and sulfenyl tetrazoles derivates in high yields.