cis-and trans-3, 6-dimethoxy-3, 6-dimethylcyclohexa-l, 4-dienes obtained by methoxylation of p-xylene were completely separated. The unequivocal structure of the trans isomer was assigned by X-ray diffraction, and the cis: trans ratio is satisfactorily explained by an EEC, C, mechanism. When the substrates were p-and o-xylene, the nuclear-addition products were obtained in a two-electron process, but when the substrate was m-xylene, the major ...
