Stereochemistry of chiral pentacoordinate spirophosphoranes correlated with solid-state circular dichroism and 1H NMR spectroscopy

Two sets of diastereomers of pentacoordinate spirophosphoranes separately derived from L-valine (or D-valine) and L-leucine (or D-leucine) were synthesized, isolated, and structurally characterized both in the solid state (X-ray crystallography and solid-state CD spectroscopy) and in the Solution (H-1 NMR). The Lambda and Delta absolute configurations of a pair of enantiomers 3a and 4a with distorted trigonal bipyramids (TBPs) geometry are directly determined by X-ray diffraction analysis, respectively. The chiral-at-phosphoros features of the related diastereomers were correlated with their solid-state CD and H-1 NMR spectra. (C) 2009 Elsevier Ltd. All rights reserved.