Recent Advances in Intramolecular Alkyne Cyclotrimerization and Its Applications

Transition-metal-catalyzed or -mediated intramolecular [2 + 2 + 2] alkyne cyclotrimerizations are one of the most efficient method to construct highly substituted arene frameworks in a single operation. The recent developments of novel catalyst systems as well as new strategies render the intramolecular cyclotrimerizations more and more attractive tools in practical organic synthesis. This review surveys most recent research works on the intramolecular alkyne cyclotrimerizations published from 2000 to 2004. The synthetic potential of the intramolecular alkyne cyclotrimerization is also discussed with respect to the recent applications to the synthesis of natural products and artificial functional molecules. Keywords: cyclotrimerization, ruthenium catalysis, cycloaddition, regiochemistry, electron-withdrawing ability, tetrahydrofuran, cycloadduct, 1-alkynylamides