QUANTUM CHEMICAL MODELING OF CHIRAL CATALYSIS - ON THE MECHANISM OF CATALYTIC ENANTIOSELECTIVE REDUCTION OF CARBONYL-COMPOUNDS BY CHIRAL OXAZABOROLIDINES

Energies of formation and structural parameters of two model systems of oxazaborolidine type of chiral reduction catalysts (CBS reduction), their borane adducts, and formaldehyde complexes of the borane adducts were calculated by using ab initio molecular orbital methods. Energies of the formation of formaldehyde complexes in which the borane and carbonyl were cis about the B-N bond of the oxazaborolidine ring were found to be slightly positive. The corresponding trans coordination was found to be repulsive. A new class of potential chiral catalysts which also contain the substructure O-B-N was found.