Microwave-Assisted or Cu–NHC-Catalyzed Cycloaddition of Azido-Disubstituted Alkynes: Bifurcation of Reaction Pathways

Microwave irradiation promoted the intramolecular cycloaddition of 2-azidoacetamides derived from α-chiral propargylic amines, affording 1,4,5-trisubstituted triazoles <b>4</b> bearing a chiral aminomethyl side chain at C5. In contrast, for the same substrates <b>3a</b>–<b>k</b>, Cu­(I)–NHC complexes catalyzed the intermolecular cycloaddition in an unexpected desilylative fashion, leading to 1,4-disubstituted triazoles <b>5</b>. This demonstrates that 1-silyl alkynes can be employed as substrates for CuAAC with a suitable coupling partner