Dibromobenzene, dibromothiophenes, dichloro- and dibromopyridine are highly selectively mono-alkylated and arylated with Grignard or organozinc reagents in the presence of palladium complexes as catalysts.
A lignanskeleton is prepared in good yield through desulfurization of 3,4-dibenzyl-thiophene or 2,5-diaryl-3,4-dimethylthiophenes which are obtained by the nickel- or palladium-phosphine complex catalyzed Grignard cross-coupling reaction of halothiophenes.