Cascade [3+2] Nitrone–Olefin Cycloaddition and Molybdenum-Mediated Oxidative Cyclization for Polycyclic Isoxazolidines and Tetrahydropyridines

A catalytic modular strategy for synthesizing polycyclic isoxazolidines via intramolecular stereoselective [3+2] nitrone–cyclohexadienone cycloaddition is described. The resulting isoxazolidines undergo Mo(CO)6-mediated cyclization to tetrahydropyridines via reductive N–O bond cleavage. This transformation displays a broad substrate scope, delivering structurally diverse polycyclic isoxazolidines and tetrahydropyridines in moderate to good yields. The approach is straightforward and enables stereoselective construction of complex polycyclic frameworks.