Abstract An efficient synthesis of [1-13 C]-para-xylene (1a) and [2-13 C]-para-xylene (1b) is described. The incorporation of the label has been achieved by cyclocondensation of suitable 1, 5-bis (bromomagnesio) alkanes with either ethyl [1-13 C] acetate or ethyl [13 C] formate which gave [ring-13 C]-labelled dimethylcyclohexanols. Dehydration of these alcohols followed by dehydrogenation of the intermediate dimethylcyclohexenes ...
