1097729-72-0Relevant academic research and scientific papers
Boron-based diastereomerism and enantiomerism in imine complexes - Determination of the absolute configuration at boron by CD spectroscopy
Braun, Manfred,Schlecht, Sebastian,Engelmann, Marco,Frank, Walter,Grimme, Stefan
body text, p. 5221 - 5225 (2009/06/06)
Boron turns out to be a stable stereogenic center in imine complexes of aryl and alkyl boronates. Diastereomerically pure complexes 7a-c are obtained from chiral imine ligands 5a,b that are derived from the amino alcohol (R)-4. The configuration at the boron atom is determined by crystal structure analyses. Racemic boronates 10a-c, available from a condensation of aryl boronic acids 6 with the achiral imine ligand 9, can be separated into stable enantiomers by HPLC on a chiral column. The racemization barrier ΔG≠ has been determined to amount to 105-115 kJmol-1. The comparison of calculated and measured CD spectra permits to assign unambiguously the absolute configuration to boron in the enantiomeric boronate-imine complex 10a. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
