Accessing Skeletal Diversity Using Catalyst Control: Formation of n and n+1 Macrocyclic Triazole Rings

A regloselective intramolecular Huisgen cycloaddition was performed on various azido alkyne substrates giving rise to macrocyclic triazole rings. Using catalyst control, a common intermediate has been converted to two structurally unique macrocycles with either a 1,5- or a 1,4-triazole resulting in an n or n + 1 ring size. This is the first example of an intramolecular ruthenium-catalyzed Huisgen cycloaddition.