Pyrylium Compounds. 38. About the Ring Transformation of 2,4,6‐Triarylthiopyrylium Salts by Acetic Acid Anhydride to Arylbenzenes and Thiobenzophenones2,4,6‐Triarylthiopyrylium salts5react in the presence of an appropriate condensing agent (sodium acetate, carbonate, methoxide, tert‐butoxide or potassium acetate) with acetic acid anhydride to yield arylbenzenes3and thiobenzophenones6. This ring transformation represents the first example of the conversion of the moiety into the thiocarbonyl group Under the same conditions 3,5‐dimethyl‐2,4,6‐triphenylthiopyrylium perchlorate (13) forms via [1,5]‐sigmatropic rearrangement the thiobenzophenone15. The structure of the new compounds6was proved by spectroscopic methods as well as by degradation reactions. Thus, hydrogen peroxide converts6ato the known benzophenone4. Alkaline saponification gives the 2‐hydroxy‐benzophenone8, whereas heating with hydrochloric acid causes a selective cleavage of the acetoxy group to the 2‐hydrox