The Wagner-Jauregg reaction is a classic organic reaction in organic chemistry, named after Theodor Wagner-Jauregg, describing the double 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.[1][2]
The reaction is unusual in that the anhydride reacts with the aromatic ring. The presence of the alpha-phenyl group activates the styryl group for a Diels–Alder reaction even at the expense of its aromaticity. Unactivated styrene reacts instead at the alkene alone and retains the aromaticity, leading to a Styrene maleic anhydride copolymer.
In one adaptation, the first rearomatization is accomplished using high temperature and elemental sulfur, followed by a second rearomatization by decarboxylation with barium hydroxide and copper:[3]