Divergent Thio/Selenolactonization of Styrene-Type Carboxylic Acids and Amides: Synthesis of Chalcogenated Isobenzofuran-1 (3H)-ones and Isochroman-1-ones

A divergent synthesis of isobenzofuran-1(3H)-one and 3,4-dihydroisochroman-1-one derivatives has been realized through the reaction of o-alkenyl benzoic acids/amides with PhICl2 and diphenyl disulfides/diselenides. Depending on the substitution type of the o-alkenyl benzoic acid or amide, this metal-free intramolecular oxychalcogenation approach regioselectively affords isobenzofuran-1(3H)-ones or 3,4-dihydroisochroman-1-ones through 5-exo-trig or 6-endo-trig cyclization processes, respectively.