Where Rh is aryl or heteroaryl and L is a leaving group, e.g. bromine, in the presence of a base e.g. N,N-diisopropylethylamine, and a suitable solvent e.g. dioxane and a suitable transition metal catalyst e.g. di(palladium)tris(dibenzylideneacetone) and a suitable ligand e.g. 2-(di-t-butylphosphino)biphenyl under an inert atmosphere e.g. nitrogen, at a temperature 20???100??? C. preferably 40???