Concise Synthesis of 7-Deoxypsammaplysins K and O and 7-Deoxyceratinamide A by 1,3-Dipole Cycloaddition.

A spiro-oxepin isoxazoline skeleton was constructed via 1,3-dipole cycloaddition as a key step, which enabled the total syntheses of 7-deoxyceratinamide A and 7-deoxypsammaplysins K and O. The developed chemistry could be applied to total synthesis of structurally diverse spiro-oxepin isoxazoline-based marine natural products.