Recent advances in the intramolecular cyclizations of nitrones.

Nitrones are versatile building blocks and their intramolecular cyclizations have served as powerful strategies to construct useful and important N-heterocycles. This review summarizes recent advances in the intramolecular cyclizations of nitrones for the preparation of distinctive N- or N,O-heterocycles over the past fifteen years. Herein, we focus on various cyclizations of N-alkyl, N-aryl, N-alkenyl, and N-allenyl nitrones, including direct cyclization, O-transfer reaction, electrocyclization, skeletal rearrangement, intramolecular cycloaddition, and related cascade reactions, and their applications in the total synthesis of natural products and alkaloids through intramolecular cyclization of nitrones.