Abstract
Although salicylaldehyde azine (
3
) was reported in 1985 as the single product of the reaction of ethyl 2-oxo-2
H
-chromene-3-carboxylate (
1
) with hydrazine hydrate, we identified another main reaction product, besides
3
, which was identified as malono-hydrazide (
4
). In the last two decades, however, some articles have claimed that this reaction afforded exclusively hydrazide
2
and they have reported the use of this hydrazide
2
as a precursor in the syntheses of several heterocyclic compounds and hydrazones
6
. We reported herein a study of the formation of
2
and a facile route for the synthesis of the target compounds
N'
-arylidene-2-oxo-2
H
-chromene-3-carbohydrazides
6a
–
f
.