First examples of the catalytic asymmetric ring-opening of meso 1,2-dioxines utilising cobalt(ii) complexes with optically active tetradentate Schiff base ligands: formation of enantio-enriched cyclopropanes

The combination of chiral cobalt beta-ketoiminato or cobalt salen complexes and meso 1,2-dioxines leads to catalytic asymmetric ring-opening affording enantio-enriched cis gamma-hydroxy enones; subsequent capture by an ylide affords enantio-enriched cyclopropanes.