A DENSITY FUNCTIONAL STUDY OF COPPER-CATALYZED CYCLOPROPANATION

^aTorben Rasmussen and ^aPer-Ola Norrby, and ^bTom Ziegler

Department of Medicinal Chemistry, Royal Danish School of Pharmacy, Universitetsparken 2, DK 2100 Copenhagen, Denmark and Department of Chemistry, University of Calgary, Calgary, Alberta Canada T2N 1N4.

A density functional study of the copper-catalyzed asymmetric cyclopropanation has been performed. Experimental systems and smaller model systems have been studied in order to explore both electronic and steric aspects. We have concentrated on the systems with the neutral bis(oxazoline) ligands reported by Evans et al. Several potential intermediates have been examined with the major focus on a copper(I) carbene in a singlet electronic state. Our Primary objective has been to elucidate what step along the pathway controls the enantioselectivity.