The Friedel-Crafts condensation of toluene (I) with itaconic anhydride (2-methylenesuccinic anhydride) (II) by means of AlCl3 in methylene chloride or 1,2-dichloroethane gives 3-(4-methylbenzoyl)-2-methylenepropionic acid (III), which is then treated with thioacetic acid (IV) and K2CO3 in DMF/water.