Compatibility between the cysteine-cyclopentenedione reaction and the copper(i)-catalyzed azide-alkyne cycloaddition.

The cysteine-cyclopentenedione reaction can be combined with the copper(i)-catalyzed azide-alkyne cycloaddition provided that the former is carried out first. If not, the azide and the cyclopentenedione undergo a 1,3-dipolar cycloaddition, which furnishes triazole-containing compounds and products resulting from nitrogen loss. Both of these products were fully characterized.