Asymmetric copper catalyzed azide-alkyne cycloadditions

Since its discovery independently by Sharpless and Meldal in 2002, the copper-catalyzed azide–alkyne cycloaddition (CuAAC) has become a ubiquitous molecular linking platform. Easy access to substituted 1,4-triazoles can be exploited to engender asymmetry to a myriad of potentially useful targets in high yields. Utilizing the CuAAC to form chiral triazolic products in a single step is an attractive and powerful approach for the synthetic chemist. The area of asymmetric CuAAC is still in its infancy compared to more established asymmetric metal-mediated transformations; however, this leads to exciting challenges that need to be overcome to usher in the next era in the story of the triazole and click chemistry in general. This review details the steps taken into asymmetric CuAAC and the exciting results achieved thus far. [Note that diagrams accompany this abstract in the published version and can be found at http://dx.doi.org/10.1021/acscatal.6b00996.]