Conjugated Azoalkenes: Attractive Products and Versatile Intermediates

Construction of bis-, tris- and tetrahydrazones by addition of azoalkenes to amines and ammonia

“…After brief optimization of the reaction conditions (solvent, base and ratio of reagents), it was found that alkylation of benzylamine with 2.0 equiv of Boc-hydrazone 1a and 2.0 equiv of potassium carbonate as a base in MeOH led to bishydrazone 2a in highest yield. The bright yellow color appeared in course of reagents mixing indicating the formation of azoalkene intermediate A [35–39]. Under these conditions, a range of other α-halogen hydrazones 1b–d , f , g were successfully converted to corresponding bishydrazones 2b–d , f , g in good to high yields (Table 1).…”

“…In the present work, we focused on the development of a general approach to tertiary amines and polyamines bearing several hydrazonomethyl arms at the nitrogen atom(s). To achieve this goal, we suggested a straightforward methodology based on multiple Michael-type additions of azoalkenes A (generated from α-halogen azacarbonyl precursor 1 [35–39]) to amines or ammonia (Scheme 1). …”

“…It has been demonstrated that amines react with azoalkenes A forming α-aminohydrazones (Scheme 1) [35–49], however, addition of several azoalkene molecules to amines is virtually unknown. To our knowledge, there is only one report on the formation of bishydrazones as undesirable products in reactions of some primary amines with N -tosylhydrazone of o -bromophenacyl bromide [50].…”

1,2-Diaza-1,3-butadienes: just a nice class of compounds, or powerful tools in organic chemistry? Reviewing an experience

“…Here, we use the name 1,2-diaza-1,3-butadienes (DBD). [1][2][3][4][5] We started our investigations at the end of the 1970s, hardly believing that our adventure would continue for nearly twenty-five years.…”

Study of the reaction between conjugated azoalkenes and α-unsubstituted- or α-substituted-β-dicarboxylate derivatives: an improved preparation of unknown polyfunctionalized 1-amino-1H-pyrrol-2(3H)-ones

“…The reaction of conjugated azoalkenes with many compounds containing active methine and methylene groups gives polyfunctionalized 1-aminopyrrole derivatives via a preliminary 1,4-conjugate addition, followed by subsequent intramolecular cyclization of the hydrazonic intermediates first obtained (2).…”