Designing an Enzyme Cascade System for N-Heterocycle Synthesis

Nitrogen-containing heterocycles (N-heterocycles), as a class of pivotal molecular scaffolds, constitute a cornerstone for advancing our understanding of biological processes, enabling drug discovery, and engineering functional materials. Enzyme cascade catalysis, which leverages the one-pot linear coupling of multiple biological or chemical catalysts, presents a highly attractive strategy for the precise synthesis of complex N-heterocyclic structures from simple precursors. However, the coordinated regulation and operational compatibility of different catalysts within a single reaction environment represent a core challenge for the field’s further development. This review focuses on cascade pathway design and reaction system compatibility, systematically summarizing recent advances and strategies in the enzymatic cascade synthesis of N-heterocycles, encompassing over 30 biocatalysts, such as transaminases, imine reductases, and oxidoreductases. It details the construction strategies for different cascade pathways, such as linear, parallel, and modular cascades, and provides an in-depth exploration of cutting-edge strategies for enhancing the compatibility and stability of multienzyme/catalyst systems. It aims to provide a theoretical foundation and methodological guidance for the building of efficient and robust enzyme cascade synthesis platforms. Finally, we demonstrate the application potential of the aforementioned strategies in synthesizing diverse N-heterocyclic structures through representative examples and provide an outlook on the opportunities and future development directions in this field.