Ring transformation reaction of 1,2,4,5-tetrazines to 4-aminopyrazoles by cyanotrimethylsilane

Asymmetric Ring Opening in a Tetrazine‐Based Ligand Affords a Tetranuclear Opto‐Magnetic Ytterbium Complex

“…However, if O11 was changed to nitrogen during the refinement process, the observed thermal ellipsoids no longer gave reasonable parameters, indicating the element is most likely oxygen. The decomposition of the central tetrazine ring of bpztz is likely metal‐assisted, as similar behaviour has been observed in other 1,2,4,5‐tetrazine‐based ligand systems [15–22] . However, to the best of our knowledge, such an asymmetric ring opening not been previously observed in the presence of lanthanides.…”

“…The decomposition of the central tetrazine ring of bpztz is likely metal-assisted, as similar behaviour has been observed in other 1,2,4,5-tetrazine-based ligand systems. [15][16][17][18][19][20][21][22] However,t ot he best of our knowledge, such an asymmetric ring openingn ot been previously observed in the presence of lanthanides. Due to the Yb 3 + metal centres, 1 possesses the potentialt oh ave both interesting magnetic and/or photoluminescencep roperties, making it the first such asymmetrict etrazine ring-opened compound to possesso pto-magnetic behaviour.T owards that end, in order to determine and compare the energy levels of the complex and have am ore complete understanding of any luminescent or magnetic behaviour,w e performed static and dynamic magnetic measurements, photoluminescence studies, and theoretical calculations for 1.…”

“…However, serendipitous transformation of the ligand might occur upon interaction with the metal centre. This is well highlighted in the family of 1,2,4,5‐tetrazine‐based ligands [15–22] . These molecules are of interest in coordination chemistry due to their facile functionalisation and their redox activity, which can enhance magnetic communication between metal ions [23–26] .…”

“…This is well highlighted in the family of 1,2,4,5-tetrazine-based ligands. [15][16][17][18][19][20][21][22] These molecules are of interesti nc oordination chemistry due to their facile functionalisationa nd their redoxa ctivity,w hich can enhancem agnetic communication between metal ions. [23][24][25][26] For these reasons, the quest for tetrazine-based compounds is an extremely activef ield of research in coordinationc hemistry.…”

Enaminonitriles in Heterocyclic Synthesis: A Route to 1,3-Diaryl-4-aminopyrazole Derivatives

“…4-Aminopyrazoles has been generally prepared via nitration of pyrazoles and subsequent reduction of the formed 4-nitropyrazole but such approach requires discarding large amounts of hazardous acid waste [1,2], which could be minimized as recently reported [7]. The ring transformation reaction of 1,2,4,5-tetrazines to 4-aminopyrazoles by cyanotrimethylsilane (TMSCN) [8]; addition of nitrile imines to benzo-1,4-oxazines [9] or reaction of ethyl diazoacetate with benzyl cyanide are alternate routes to 4-aminopyrazoles [10], but again these either utilize explosive starting materiales or rather expensive ones. A route to 4-aminopyrazoles via a Gabriel-like synthesis has also been recently reported, but this approach is not atom economic and also employs expensive dimethylformamide dimethylacetal (cf.…”