Various N-vinyl- and N-allyl-amides of 2-iodobenzoic acid undergo catalytic cyclisation in the presence of tetraethylammonium chloride and a palladium acetate-based catalyst system to generate a range of synthetically useful structural features including tetrasubstitutedcarboncentres, and spiro- and bridged-ringcompounds, and in which 5-exo-trig cyclisations are kinetically favoured.
(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
Palladium catalysed cyclisations creating products possessing spiro-, fused- and bridged-rings, and tetrasubstituted carbon centres as mixtures of double bond isomers are modified to give single products in the presence of Tl(1) salts.