Lewis acid-catalyzed Wolff cyclocondensation in the synthesis of (1H-1,2,3-triazolyl)furoxans

Abstract

Novel regioselective approach to the synthesis of (1H-1,2,3-triazol-1-yl)furoxans based on Lewis acid-catalyzed Wolff cyclocondensation of aminofuroxans with diazo-β-dicarbonyl compounds has been developed. This approach allows to involve aminofuroxans as substrates which are very weak nucleophiles and usually do not participate in reactions with common electrophiles.

Synthesis, structural characterization and cytotoxic activity of heterocyclic compounds containing the furoxan ring

“…Among many other intermolecular contacts, the shortened contacts between the oxygen atom of morpholine cycle and furoxan cycle are to be noted (the С(1)…О(3), N(1)…O(3) and C(2)…O(3) distances are 2.950, 2.970, и 3.158 Å, respectively). These contacts are geometrically similar with intermolecular interactions between furoxan ring and its exo-oxygen atom 29,41 and can be described as interaction between lone electron pair of the O(3) atom and π*-orbital of the furoxan cycle. In 5k these interactions form continuous chains of molecules which are, in its turn, bounded into layers by the C-H… π interaction between CH 2 -fragment and triazole ring (with normalized C-H bonds the С(3)…H(11B) distance is 2.598 Å).…”

Diazocarbonyl and Related Compounds in the Synthesis of Azoles

“…Even poorly nucleophilic amines, such as aminofuroxans 348 , can be employed for this reaction, as was shown by Fershtat and co-authors [ 172 ]. The use of 20 mol.% of boron trifluoride etherate at room temperature proved to be the optimal conditions for this substrate, although the desired triazoles 350 were obtained in low to moderate yields.…”

Impact of regiochemistry in energetic materials science: a case of (nitratomethyl-1,2,3-triazolyl)furazans

“…The only known analogue, i.e. the substituted triazolylfuroxan (CSD refcode FAZGOF, 37 Fig. S1 †), is characterized by the corresponding angle of 79.4°.…”