Green Multicomponent‐Click Strategy for One‐Pot Synthesis of Polyheterocyclic Estazolam Aza‐Analogs and Their Symmetrical Polyheterocycles

ABSTRACT A novel one‐pot synthesis of polyheterocyclic compounds (PHCs) incorporating fused 1,5‐disubstituted 1,2,3‐triazole‐1,4‐benzodiazepines (fused 1,5‐Ds‐1,2,3‐T‐1,4‐BZD) bound to 1,5‐disubstituted tetrazoles (1,5‐Ds‐Ts) was developed via Ugi‐azide four‐component reaction (UA‐4CR), followed by an intramolecular alkyne–azide cycloaddition (IAAC). The strategy features overall yields up to 92%, the construction of three heterocycles, broad applicability to UA‐4CR products, a single purification step via flash column chromatography, green solvent conditions (water or EtOH), and scalability. The secondary amine functional group in PHCs enabled further structural diversification in the synthesis of symmetrical polyheterocycles (SPHs) and structurally aza‐analogs of estazolam. This is the first report of an alternative energy sources (AES)‐assisted UA‐4CR/IAAC strategy for the synthesis of fused 1,5‐Ds‐1,2,3‐T‐1,4‐BZD, applied to the synthesis of SPHs that allow the construction of six heterocyclic rings.