Asymmetric cyclopropanation of chiral fumarates with gem-dihalides catalyzed by Co(0) or Ni(0) complexes and zinc

Abstract

Diastereoface differentiating cyclopropanation between fumarates derived from chiral alcohols and gem-dihalides has been carried out using cobalt(0) or nickel(0) complexes and zinc. The optical yields of the cyclopropane derivatives obtained from (−)-dimenthyl and (−)-dibornyl fumarate both exhibit maximum values at 23 °C. An approximate general linearity between the highest optical yield and the optical rotation of the chiral fumarate is observed except in the case of (−)-di-8-phenylmenthyl fumarate. The high asymmetric selection may be due to preferential coordination of a face of the chiral fumarate onto the metal center where the chirality has been determined by coordination of another molecule of the chiral fumarate.