An obvious concern for large scale
applications of this type of chemistry is the cost of the metal and
the ligands as well as the need for fully removing the metal from
the product solution. The recent quest for cheap and sustainable
reactions made many researchers turn their attention again to the
copper-mediated cross-coupling reactions. The successful deve-
lopment of improved catalytic versions of this grand old chemistry
has caused a veritable ‘renaissance’ of what is now known as the
‘modified Ullmann reaction’.