This invention provides a method for preparing a 1,2,3-triazole compound comprising contacting an organic azide with a 2-substituted-1-haloalkyne, in the presence of a copper catalyst and a copper-coordinating ligand (preferably a tertiary amine) in a liquid reaction medium, thereby forming a 1,4,5-substituted-1,2,3-triazole compound including a halo substituent at the 5-position of the triazole, the organic portion of the organic azide at the 1-position of the triazole, and the substituent of the 1-iodoalkyne at the 4-position of the triazole. A method for preparing 1-iodoalkynes is also provided.