Highly Efficient Catalysis of Retro‐Claisen Reactions: From a Quinone Derivative to Functionalized Imidazolium Salts

A new and efficient method for the preparation of several imidazolium salts containing an ester group in the C4 position of the aromatic ring through a retro‐Claisen reaction pathway between a quinone derivative and several alcohols is described. This new organic transformation proceeds in the absence of a catalyst, but it is greatly catalyzed by different Lewis acids, especially with AgOAc at a very low catalyst loading and in very short reaction times. The process takes place by the nucleophilic attack of the carbonyl groups by the alcohol functionality, thus promoting a double C−C bond cleavage and C−H and C−O bond formation. This reaction represents the first example of this type between a quinone derivative and alcohols.