Asymmetric synthesis and absolute configuration of a planar chiral phosphapalladacycle with a ferrocenyl framework

A monodentate optically active tertiary alpha-ferrocenylethylphosphine was prepared from the corresponding tertiary a-ferrocenylethylamine; Me2N group substitution by a tert-Bu2P group occurs with complete retention of the enantiomeric composition and absolute configuration of the alpha-carbon stereocentre. The cyclopalladation of this phosphine ligand results in the formation of a phosphapalladacycle bearing the elements of central and planar chirality with a high diastereoselectivity. The enantiomeric composition of the CP-palladacycle was determined by P-31{H-1} NMR spectroscopy using (S)-prolinate as a chiral derivatizing agent. The structure and absolute configuration of the phosphapalladacycle were established using NMR spectroscopy and an X-ray diffraction study of its (S)-prolinate derivative. (C) 2011 Elsevier Ltd. All rights reserved.