ABSTRACT A series of novel tetracyclic heterocycles was synthesized through multicomponent reactions involving 7‐(phenylamino)‐1,2,4triazolo4,3‐ a pyrimidin‐5‐ones, 2‐(4‐formylphenoxy)‐ N ‐arylacetamides, and dimedone at reflux in acetic acid. The reaction pathway afforded products with two possible regioisomeric structures. Comprehensive spectroscopic analysis, particularly 2D‐NMR‐HMBC, was decisive in confirming the linear tetracyclic framework over the angular alternative. Alternative synthetic strategies employing alkylation of fused heterocyclic intermediates with hydrazonoyl chlorides were also explored, enabling structural diversity.
Ali et al. (Tue,) studied this question.