Abstract
Homogeneous gold catalysis has attracted intensive interest from synthetic chemists because of its significant advances in the field of carbon-carbon and carbon-heteroatom bond formations. The gold catalysts are generally recognized as soft Lewis acids which allow to activate carbon-carbon multiple bonds towards a variety of nucleophiles under mild conditions. To elucidate the precise catalytic mechanism without speculation, much effort has been devoted to the isolation and characterization of organogold intermediates. In particular, it has been proposed that various alkenylgold complexes play crucial roles as the active species involved in catalytic transformation of alkynes and allenes. This paper overviews recent advances in the synthesis of alkenylgold complexes relevant to catalysis and focuses mainly on mechanistic insights into the intramolecular cyclization of alkyne and allene substrates containing hetero- and carbonucleophiles with the aim of contributing to a further understanding of the unique and distinctive gold-catalyzed reactions.
