Enantiopure 2,2'-dihydroxy-3,3'-dimethoxy-5,5'-diallyl-6,6'-dibromo-1,1'-biphenyl: a conformationally stable C2 dimer of eugenol derivative.

The preparation and resolution of the title conformationally stable biphenyl 9 has been performed in high chemical yield starting from eugenol 1. Enantiopure biphenyls (aR)-(+)-9 and (aS)-())-9 were achieved, respectively, by resolution of the corresponding menthylcarbonate diastereomer and subsequent reduction. Absolute configuration and specific rotation were correlated by X-ray analysis of the crystal structure of diastereopure phosphorothioamidate (aR,S)-())-16.