Visible‐Light‐Mediated Oxidative Desulfurization‐Oxygenation in Cyclic Thio‐Amide

Abstract

AbstractVisible‐light assisted a very simple and mild protocol for photocatalytic oxidative transformation of thioamide to amide group has been realized in cyclic system. For this purpose 5‐arylalkylidene‐rhodanine derivatives were chosen as model substrates to afford thiazolidine‐2,4‐diones. Light mediated reactions are intrinsically beneficial, since activation occurs by cleanest energy source light. Here K2S2O8 is used as terminal oxidant which does not leave any hazardous and corrosive waste to discard after the reaction fostering the practices of green chemistry. This is the first report of conversion of thioxo group in rhodanine derivatives into the corresponding oxygen analogue by visible light photo‐catalytic method. The reaction was very general since various 5‐arylalkylidene‐rhodanines underwent the reaction smoothly affording high product yields. Moreover, the broadness of this protocol was further established by applying this reaction on other systems like 3,4‐dihydropyrimidine‐2(1H)‐(thio)ones.