The reviewed reactions were classified according to the active centers of cyanoacetohydrazide involved. Accordingly, they are divided into the following classes: a -Heterocycles obtained via the utility of functional groups No. 1, 2 ( The cyano and methylene groups . ) involving the cyano group of 1 together with the oxygen or nitrogen nucleophile from the other reagent to form heterocyclic compounds. Thus, El-Moghayer et al reported that, the reaction of 1 with benzylidenes 4 or 5 in boiling ethyl alcohol in the presence of piperidine, as a basic catalyst, gave the corresponding pyranopyrazole 6 and thiazolopyridine 7, respectively (Scheme 2a,b).