(and in some cases rhodium) catalysed regiospecific 5-exo-, 6-endo-and 6-exo-trig cyclisations of aryl iodides and vinyl bromides onto proximate alkenes or heteroaromatic rings (indole, pyrrole) lead to a wide variety of fusedring systems. In appropriate cases the methodology provides a facile approach to the creation of tetrasubstituted carbon centres. Double bond isomerisation in the product is only