The chemistry of polyfluorinated azides

In 2017, we reported a breakthrough in azide chemistry. CF₃N₃ and longer carbon chain analogues were prepared from silanes or other carbanion precursors, which opened a door to study properties and reactivity of these compounds. They are no longer regarded as chemical curiosities. Furthermore, they were shown to be stable and not explosive (Angewandte Chemie International Edition  56: 346, 2017). Subsequently, other fluorinated azides such as HCF₂N₃ (European Journal of Organic Chemistry 5087, 2018), BrCF₂N₃, BrCF₂CF₂N₃ (Journal of Organic Chemistry  85: 11482, 2020), RCF₂CF₂N₃ (Organic and Biomolecular Chemistry  15: 4962, 2017) and FCH₂N₃ (Organic Chemistry Frontiers  7: 10, 2020) were prepared. They readily underwent copper(I)-catalyzed azide-alkyne cycyloadditions (CuAAC) and enamine-mediated azide-ketone cycloadditions (ChemistrySelect  3: 7045, 208) to form novel N-perfluoroalkyl triazoles. Preparation and reactivity of fluorinated azides was recently reviewed (Chemistry – A European Journal 773, 2020).

In the presence of superacids, azidotrifluoromethane protonates on nitrogen one to trifluoromethylamino diazonium cations (CF₃NHN₂)⁺ (Angewandte Chemie International Eddition  59: 12520, 2020) (collaboration with University of Southern California).

Heating N-(per)fluoroalkyl triazoles in the presence of rhodium catalyst allows to enter rhodium carbene chemistry for the synthesis of novel N-(per)fluoroalkyl pyrroles, imidazoles, azepines, oxazoles, thiazoles and other heterocycles (Chemical Communications  54: 3258, 2018, Journal of Organic Chemistry  83: 15195, 2018, Organic Chemistry Frontiers  6: 3776, 2019).

A new reactive mode was discovered in N-(per)fluoroalkyl triazoles. In the presence of superacids, such as triflic acid or fluorosulfonic acid, the triazoles ring open and vinyl triflates enamides are formed via a vinyl cation (Chemistry – A European Journal  25: 7640, 2019).