New synthetic applications and biological activity of diazenes

Reactivity of Azasydnones: Unusual Diversity in Reactions of Chloro‐ and Nitrophenyl Derivatives with Nitrogen Nucleophiles

“…The second product was a result of another destruction of the azasydnone ring, and was a 2‐phenyldiazene‐1‐carboxamide derivative ( 12 a – c , 13 a – c ) (Table ). 2‐Aryldiazene‐1‐carboxamide and derivatives have previously been shown are versatile reagents in biochemistry and in organic synthesis and can serve as replacements of dialkyl azodicarboxylate…”

The Hydrazine–O2 Redox Couple as a Platform for Organocatalytic Oxidation: Benzo[c]cinnoline‐Catalyzed Oxidation of Alkyl Halides to Aldehydes

“…Towards this goal, we took note of the fact that 1,2disubstituted hydrazines 2 are well known to undergo facile autoxidation to generate diazenes 1 ( Figure 1A). [10] We recognized that ap rocess involving diazene-mediated oxidation of as ubstrate [11] along with spontaneous reoxidation of the resulting hydrazine 2 would represent an ovel and rare direct organocatalytic O 2 -coupled oxidation. One blueprint for this type of transformation is outlined in Figure 1B.T hus diazene catalyst 1 would be alkylated by an electrophilic substrate 3 to generate ad iazenium intermediate 4.P rototropic isomerization of the diazenium would then reveal ah ydrazinium intermediate 5,w hich would be prone to hydrolysis to furnish ac arbonyl product 6 along with the reduced catalyst 2.F inally,f acile autoxidation (2!1)w ould close the catalytic cycle.H erein, we describe the first realization of this concept in the context of an organocatalytic oxidation of organohalides to aldehydes using benzo- [c]cinnoline (BCC), ac ommercially available diazene known to be exceptionally difficult to maintain in its reduced form ( Figure 1C).…”

Diazenes as Powerful and Versatile Tools in Organic Synthesis

“…[15][16][17] The latter reagent was successfully applied in the synthesis of either (alkylcarbamoyl)-or (arylcarbamoyl)diazenecarboxylates 2 18 and diazenecarboxamides 4, 19 as well as alkyl (hetero)aryldiazenecarboxylates. 20 Other cerium(IV) salts, e.g.…”