Wagner-Jauregg reaction

The Wagner-Jauregg reaction is a classic organic reaction in organic chemistry (named after its inventors) describing the Diels-Alder reaction of 2 equivalents of maleic anhydride with a 1,1-diarylethylene. After aromatization of the bis-adduct the ultimate reaction product is a naphthalene compound with one phenyl substituent.

The reaction is unusual in that the anhydride reacts with the related styrene to form a copolymer. The presence of the alpha-phenyl group activates the styryl group for a Diels–Alder reaction even at the expense of its aromaticity.

In one adaptation rearomatization is accomplished with elemental sulfur and decarboxylation with barium hydroxide and copper: