Copper-CatalyzedDiastereoselective Addition of a[1,1,1]Propellane Dimer to <i>N</i>-<i>tert</i>-Butanesulfinyl Aldimines

[1,1,1]Propellane is typically used as a building block for the construction of bicyclo[1,1,1]pentanes and cyclobutanes. In this work, diverse chiral bi(methylenecyclobutylidene) complexes were synthesized by a diastereoselective addition of the [1,1,1]propellane dimer to <i>N</i>-<i>tert</i>-butanesulfinyl aldimines in the presence of copper and bipyridine. Density functional theory calculations revealed that both the addition step and regeneration of the copper catalyst contributed to the diastereoselective generation of the favored (<i>S</i>s,<i>S</i>,<i>S</i>)-diastereomer.