Selective Functionalization of Norbornadiene Through Nitrile Oxide Cycloaddition/Ring-Opening/Cross-Metathesis Protocols

This work describes a study on the selective functionalization of norbornadiene across nitrile oxide 1,3-dipolar cycloaddition/ring-opening (ROM)/cross-metathesis (CM) protocols. Readily available norbornadiene was transformed into novel bicyclic scaffolds with multiple chiral centers. The described syntheses involved selective cycloadditions followed by ring-opening metathesis of the resulting cycloalkane-fused isoxazoline derivatives, and selective cross-metathesis by chemodiscrimination of the C=C bonds of the resulting alkenylated heterocycles. The cross-metathesis transformations have been studied under various experimental conditions with the aim of exploring the substrate influence and chemodifferentiation of the olefin bonds providing the corresponding functionalized isoxazoline derivatives.