MOLECULAR MECHANICS PREDICTIONS AND EXPERIMENTAL TESTING OF ASYMMETRIC PALLADIUM-CATALYZED ALLYLATION REACTIONS USING NEW CHIRAL PHENANTHROLINE LIGANDS

Molecular mechanics calculations were used to probe the conformational properties of a number of substituted phenanthrolines and their eta(3 )-allylpalladium complexes. Special attention was focused on phenanthr olines bearing chiral, terpene-derived, alkyl and alkenyl groups at C( 2). Based upon these calculations, predictions could then be made rega rding the suitability of the several ligands for use in asymmetric pal ladium-catalyzed substitution reactions of allylic acetates. Each of t he substituted phenanthrolines was prepared by straightforward means. Use of these ligands in catalytic allylations gave results which were in good agreement with the calculation-based predictions. The highest levels of asymmetric induction were predicted and were obtained with a readily available 2-(2-bornyl)phenanthroline ligand 13. The results w ere compared with previously reported data obtained using other ligand s. Overall, this work provides further indication of the potential uti lity of a combined calculational/experimental approach for the design of chiral catalysts.