Synthetic Approaches and Reactions of 2-(Arylidene)benzo[b]thiophen-3(2H)one-1,1-dioxides

Abstract: 2-(Arylidene)benzo[b]thiophen-3(2H)one 1,1-dioxides are oxidized form of thioaurones. Various methods have been reported for their synthesis, e.g., a) condensation of benzo[b]thiophen-3(2H)one 1,1-dioxides with aryl aldehydes under acidic or basic conditions, b) oxidation of thioaurones with hydrogen peroxide or sodium perborate tetrahydrate, c) from the catalytic reaction of iodonium ylides with (bis(trifluoroacetoxy)iodo) benzene in presence copper(II)acetoacetonate, d)by ring contraction of 1-thioflavones in the presence of ceric ammonium nitrate. The reports have shown addition reactions with p-thiocresol in the absence of any catalyst, conjugated addition product without hetero ring opening with Grignard reagent, forms corresponding oxime and hydrazone with hydroxyl amine and phenyl hydrazine, respectively, produces polycyclic compounds with enamines, shows contrasting behavior with NBS and gives addition products with organophosphorus compounds in both hydroxylic and non-hydroxylic solvents which depends on reaction medium. In the present mini-review, we have discussed the various synthetic strategies and reactions of 2-(arylidene)benzo[b]thiophen-3(2H)one 1,1-dioxides, along with their reported utilities.