A DFT study of the enantioselective reduction of oxime ethers promoted by chiral spiroborate esters

Abstract

Mechanisms of borane reduction of the (E)-acetophenone O-methyl oxime catalyzed by the easily prepared and stable spiroborate ester 1, derived from diphenylvalinol has been reported for the first time using density functional theory. Two reaction pathways are investigated at the B3LYP/6-31G(d,p) level of theory. The calculated results reveal that this reaction is accomplished via four steps. All the reactants, products, transition states, and intermediates have been optimized at the B3LYP/6-31G (d,p) level. The analysis of these results reveals that one pathway is more energetically favorable than the other, and its associated product is in good agreement with the experimental result. The solvent effect has been further considered at the B3LYP/6-31G(d,p) level in the solvent THF using the PCM model, and the results indicate that it has no great influence on the enantioselectivity of this reduction. (C) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012