Unleashing the Power of Vilsmeier–Haack Reaction in Synthesis of Heterocycles (A Review)

Vilsmeier–Haack reaction (VHR) serves as a versatile approach for synthesizing electron-rich aromatic and heteroaromatic compounds via effective formylation (aldehyde group production). The reaction attains its synthesis objective via substituted amide and phosphorus oxychloride, used as the Vilsmeier reagent, to construct an intricate molecular framework of considerable medicinal importance. Modifications of VHR, such as the use of catalysts or alternative reagents, can enhance its selectivity and improve environmental sustainability, and cost-efficiency in chemical processes. This review examines VHR mechanics via synthetic applications that facilitate the building of heterocyclic scaffolds. This review aims to provide a foundation for the exploration of novel methodologies in heterocyclic architecture research, culminating in the synthesis of prospective medications.