Direct synthesis of 2-/3-(trifluoromethyl)thiochroman-4-ones: Superacid-induced tandem alkylation-cyclic acylation of benzenethiols using 2-/3-(trifluoromethyl)acrylic acid

[Display omitted] Direct one-pot synthesis of 2-/3-(trifluoromethyl)thiochroman-4-ones is achieved by a superacid induced tandem S-alkylation-cyclic acylation. •Direct one-pot synthesis of 2-/3-(trifluoromethyl)thiochroman-4-ones is achieved.•2-/3-(Trifluoromethyl)acrylic acid is used as an effective CF3 motif.•Reaction occurs by superacid induced tandem S-alkylation-cyclic acylation.•A reactive superelectrophilic dicationic species is proposed as the key intermediate. Incorporation of fluorinated heterocyclic framework into organic molecules results in profound changes in their physical, chemical and biological properties. Realizing that the fluorinated thiochroman-4-ones are important scaffolds in medicinal chemistry and are rare in the chemical literature, one-pot synthesis of 2-/3-(trifluoromethyl)thiochroman-4-ones was attempted. Direct access to 2-/3-(trifluoromethyl)thiochroman-4-ones was achieved by a tandem alkylation-cyclic acylation process promoted by superelectrophilic activation of 2-/3-(trifluoromethyl)acrylic acid in superacidic trifluoromethanesulfonic acid under microwave-assisted Friedel-Crafts alkylation of benzenethiols followed by cyclization (via intramolecular acylation). Synthesis of a series of 2-/3-(trifluoromethyl)thiochroman-4-ones from protosolvated 2-/3-(trifluoromethyl)acrylic acid intermediates and benzenethiols is described.