Advancements in the mechanistic understanding of the copper-catalyzed azide–alkyne cycloaddition

• Regina Berg and
• Bernd F. Straub

Beilstein J. Org. Chem. 2013, 9, 2715–2750, doi:10.3762/bjoc.9.308

• °C to give the 5-bromo-1,4-disubstituted-1,2,3-triazoles with small quantities of the 5-iodo-1,4-disubstituted-1,2,3-triazole as byproduct. Obviously, the alkynyl halide substrate can exchange its halide group for other halide ions present in the reaction mixture, which means that the formation of

Iridium-catalyzed intramolecular [4 + 2] cycloadditions of alkynyl halides

• Andrew Tigchelaar and
• William Tam

Beilstein J. Org. Chem. 2012, 8, 1765–1770, doi:10.3762/bjoc.8.201

• –94%). These results are the first examples of cycloadditions of alkynyl halides using an iridium catalyst. Keywords: alkynyl halide; cycloaddition; diene-tethered alkyne; iridium; transition-metal catalyst; Introduction Iridium complexes have been used as catalysts for a wide variety of reactions

• proceeded smoothly at 90 °C to afford the bicyclic products in good yields, and oxidative insertion of the iridium into the carbon–halide bond did not appear to be a problem. In addition to the known compounds synthesized, two previously unreported alkynyl halide substrates were synthesized, and were also

• examples of intramolecular TMC [4 + 2] cycloadditions of diene-tethered alkynes. Reaction pathways of alkynyl halides in transition-metal-catalyzed reactions. Synthesis of diene-tethered alkynyl halides 1c and 1e. Synthesis of diene-tethered alkynyl halide 1g. Unsuccessful cycloaddition attempts with