ONE of us1 has earlier obtained a small amount of a crystalline compound (m.p. 241°, decomp.) of anethole with two moles of maleic anhydride, the main bulk of the reaction product being a hetero-polymer1,2,3. We found that, if a small amount of dimethylaniline is added, the formation of the hetero-polymer product is prevented and the yield of the crystalline adduct was as high as 60 per cent. We have confirmed the structure previously proposed1 and our work led further to the determination of the steric configuration of the compound.