Asymmetric Construction of Spirocyclic Pyrrolidine-thia(oxa)zolidinediones via N,O-Ligand/Cu(I) Catalyzed 1,3-Dipolar Cycloaddition of Azomethine Ylides with 5-Alkylidene Thia(oxa)zolidine-2,4-diones.

A highly efficient asymmetric 1,3-dipolar cycloaddition of azomethine ylides to 5-alkylidene thia(oxa)zolidine-2,4-diones catalyzed by a chiral N,O-ligand/Cu(CH3CN)4BF4 system is reported, affording structurally novel spirocyclic pyrrolidine-thia(oxa)zolidinediones with a spiro-heteroquaternary stereogenic center in good to excellent yields (up to 99%), with excellent levels of diastereo- and enantioselectivity (dr up to 99:1; ee up to 98%).