Diethylzinc-mediated allylation of natural biphenyls by ð-1,1-dimethyleneallylpalladium complexes

1-Ethenylcyclopropyl sulfonate underwent electrophilic gamma- and alpha-substitutions by the carbonyls of naturally occurring biphenyls derived from vanillin and acetovanillone, in the presence of palladium(0) and diethylzinc, to provide regioisomeric 5,5'-di(3-cyclopropylidene-1-hydroxypropyl) biphenyls and 5,5'-di[1-(1-ethenylcyclopropyl)-1-hydroxymethyl]biphenyls of biological interest.