6-Hydrazinonicotinic acid hydrazide: an useful precursor for chemo- and regioselective synthesis of new heteroaryl-linked pyridinohydrazones

Abstract

In order to demonstrate the reactivity differentiation between the two dinucleophilic centers in the 6-hydrazinonicotinic acid hydrazide hydrate (1), a series of seven new 6-[(2-(arylidene)hydrazinyl]nicotinohydrazides (4) was chemoselectively accessed from the reaction of 1 with seven aryl or heteroaryl aldehydes by a simple procedure in ethanol as solvent. In a subsequent study, cyclization reactions of 4 with some 4-alkoxy-1,1,1-trifluoroalk-3-en-2-ones or triethylorthoacetate were proceeded easily also in ethanol, an eco-friendly solvent, to give regioselectively nine examples of pyrazolinyl-pyridinohydrazones and one 1,3,4-oxadiazole derivative, respectively, as stable and pure compounds in good yields.

Acid Hydrazides, Potent Reagents for Synthesis of Oxygen-, Nitrogen-, and/or Sulfur-Containing Heterocyclic Rings

“…1,3,4-Oxadiazole derivative 187 was obtained with 64% yield from 6-(2-(4-chlorobenzylidene)hydrazino)nicotinic hydrazide by a [4 + 1] cyclocondensation reaction with triethylorthoacetate (Scheme 54). 133 Sureshbabu et al 134 reported the synthesis of S-linked 1,3,4oxadiazole-tethered N α -protected peptidomimetics under sonication using acid hydrazides as synthetic precurssor.…”

“…1,3,4-Oxadiazole derivative 187 was obtained with 64% yield from 6-(2-(4-chlorobenzylidene)­hydrazino)­nicotinic hydrazide by a [4 + 1] cyclocondensation reaction with triethylorthoacetate (Scheme ) …”

Applications of alkyl orthoesters as valuable substrates in organic transformations, focusing on reaction media

“…In this transformation, the hydrazine and the hydrazide moieties exhibited similar reactivity, whereas in the presence of aldehyde as one other carbon donor moiety the hydrazine and the hydrazide groups were treated chemoselectively and regioselectivly. 225 …”