Noncovalent sulfur···oxygen interactions can increase the stability of chalcogen ortho-substituted phenoxyl radicals. This effect contributes to transforming the 7-hydroxybenzo[b]thiophene moiety in a privileged structural motif to enhance the activity of phenolic antioxidants. A cascade of five consecutive electrophilic reactions occurring in one pot afforded potent and biocompatible α-tocopherol-like antioxidants.

Simple phenols, including food stock recycled derivatives, were used for the synthesis of 1,4-benzooxathiine intermediates, with limited or no antioxidant activity. Depending upon their substitution pattern, these compounds, through an acid promoted transposition, can be converted into o-hydroxydihydrobenzo[b]thiophenes or o-hydroxy-benzo [b]thiophenes as a new class of potent chain-breaking antioxidants, showing, in the reaction with alkyl peroxyl radicals, kinetic rate constants (kinh) comparable to that of −tocopherol, the more potent natural lipophilic phenolic antioxidant.