%A P Wipf
%A N Jayasuriya
%A S Ribe
%J Chirality
%T On the role of chiral catalysts in the alkenyl zirconocene/zinc addition to aldehydes: A study of ligand loading and asymmetric amplification
%X Unusual nonlinear asymmetric amplification and chiral ligand loading effects were discovered for the use of catalytic quantities of chiral aminoalcohols in the in situ hydrozirconation - transmetalation - aldehyde addition processes. While the stereochemically most efficient aminothiol ligands demonstrated mechanistically conventional reaction parameters in excellent agreement with Kagan's ML2 system, the asymmetric induction in the presence of a chiral aminoalcohol was found to vary greatly with loading and %ee of the ligand. Aminothiols remain the ligands of choice for the highly enantioselective formation of allylic alcohols and provide experimentally more predictable reaction variables. However, new, optimized conditions lead to a synthetically useful product %ee using the readily available and scalable aminoalcohol 2a. ? 2003 Wiley-Liss, Inc.
%N 3
%P 208 - 212
%V 15
%D 2003
%R 10.1002/chir.10176
%L pittir20444