Greening the pharmacy: sustainable synthesis of heterocycles and their precursors via CO₂ valorization

The pervasive presence of heterocyclic compounds in pharmaceuticals, agrochemicals, and materials is accentuated by the environmental burden of their traditional synthetic routes, which often rely on petrochemical feedstocks and generate significant waste. Concurrently, the escalating levels of atmospheric carbon dioxide (CO₂) present a pressing global challenge. This systematic review explores the transformative synergy between these two issues by examining the direct utilization of CO₂ as a C1 building block for the sustainable synthesis of heterocycles. The present study provides a comprehensive analysis of the literature from 2000 to 2025 concerning the efficient conversion and utilization of CO₂ into valuable heterocyclic scaffolds, such as oxazolidinones, quinazoline-2,4-diones, and benzimidazoles, via various catalytic approaches. The discussion critically focuses on the green credentials of each process, emphasizing atom economy, waste reduction, and the use of renewable inputs. By framing CO₂ not as waste but as a versatile synthetic feedstock, this review aims to catalyze further innovation in greening the synthetic toolkit of modern pharmacy and organic chemistry.