Abstract Treatment of a mixture of aromatic compound and ethyl α-(methylsulfinyl) acetate (5) with p-toluenesulfonic acid under continuous removal of separated water brought about an intermolecular aromatic substitution to give ethyl α-(methylthio) arylacetate (6). Similar treatment of acylmethyl phenethyl sulfoxide (8) led to cyclization into 1-acylisothiochroman (9).