Novel Pyridine and Chromene Hybrids via Multicomponent Reactions of Cyanoacetohydrazide: Synthesis, Mechanistic Insights, and Spectral Characterization

Cyanoacetohydrazide, a versatile building block containing both nucleophilic and electrophilic sites, was exploited to develop new pyridine and chromene derivatives bearing a 4-hydroxy-3-ethoxyphenyl moiety. A series of nitrogen- and oxygen-based heterocycles were generated through multicomponent synthetic approaches using diverse aromatic aldehydes, malononitrile, ethyl cyanoacetate, and salicylaldehyde. Proposed reaction mechanisms involved sequential steps, including Knoevenagel condensation, Michael addition, and intramolecular cyclization. Structural identities of the obtained. IR and NMR spectroscopy, together with elemental analysis, supported the proposed chemical structures of the compounds, all of which verified the expected functional groups and ring frameworks. The incorporation of ethylvanillin as a primary aldehyde source enhanced the pharmacophoric potential of the final molecules. The developed procedures furnished regioselective products in excellent yields under mild conditions. Overall, the findings highlight the applicability of cyanoacetohydrazide in constructing complex heterocyclic frameworks, offering promising scaffolds for future studies in medicinal chemistry, drug design, and functional materials. These findings offer a strong basis for additional biological analysis of the produced substances.