Biomass-Based Lactams Synthesis: Feedstock-Oriented Catalytic Routes via Heterogeneous Catalysis

Nitrogen-containing chemicals are indispensable to modern society, among which lactams occupy a central position owing to their extensive use as polymer precursors, high-performance solvents, and pharmaceutical building blocks. Conventional petroleum-based production routes, however, are increasingly constrained by environmental and resource concerns, underscoring the urgency of developing sustainable alternatives from renewable biomass. Despite growing research activity, existing reviews on biomass-derived lactam synthesis remain fragmented, typically concentrating on a limited number of established pathways and lacking a systematic mapping of renewable feedstocks, reaction networks, and catalytic strategies. To bridge these gaps, this review provides a systematic overview of representative biomass-based lactams, with emphasis on γ-, δ-, and ε-lactams, by correlating diverse renewable feedstocks with their corresponding synthetic routes under heterogeneous catalysis. This work aims to establish a coherent framework for biomass valorization and to offer conceptual and practical guidance for advancing efficient, selective, and sustainable lactam synthesis.