Chiral Sc^III–N,N′‑Dioxide-Catalyzed 1,3-Dipolar Cycloaddition of Diaziridines with Chalcones

A highly enantioselective 1,3-dipolar cycloaddition of meso-diaziridines with chalcones was realized by utilizing the Sc^III–N,N′-dioxide complex as the catalyst. In this transformation, the 1,3-dipole intermediates generated from the C–N bond cleavage of diaziridine were trapped by chiral N,N′-dioxide/scandium­(III) complex activated chalcones to undergo enantioselective 1,3-dipolar cycloaddition. A range of chiral 1,5-diazabicylo[3.3.0]­octane derivatives were readily synthesized in good yields with high diastereo- and enantioselectivities.