TY - JOUR
T1 - Structure and absolute configuration of ginkgolide B characterized by IR- and VCD spectroscopy
AU - Andersen, Niels Højmark
AU - Christensen, Niels Johan
AU - Lassen, Peter Rygaard
AU - Freedman, Teresa B.N.
AU - Nafie, Laurence A.
AU - Strømgaard, Kristian
AU - Hemmingsen, Lars Bo Stegeager
PY - 2010/2
Y1 - 2010/2
N2 - Experimental and calculated (B3LYP/6-31G(d)) vibrational circular dichroism (VCD) and IR spectra are compared, illustrating that the structure and absolute configuration of ginkgolide B (GB) may be characterized directly in solution. A conformational search for GB using MacroModel and subsequent DFT optimizations (B3LYP/6-31G(d)) provides a structure for the lowest energy conformer which agrees well with the structure determined by X-ray diffraction. In addition, a conformer at an energy of 7 kJ mol-1 (B3LYP/6-311+G(2d,2p)) with respect to the lowest energy conformer is predicted, displaying different intramolecular hydrogen bonding. Differences between measured and calculated IR and VCD spectra for GB at certain wavenumbers are rationalized in terms of interactions with solvent, intermolecular GB-GB interactions, and the potential presence of more than one conformer. This is the first detailed investigation of the spectroscopic fingerprint region (850-1300 cm-1) of the natural product GB employing infrared absorption and VCD spectroscopy.
AB - Experimental and calculated (B3LYP/6-31G(d)) vibrational circular dichroism (VCD) and IR spectra are compared, illustrating that the structure and absolute configuration of ginkgolide B (GB) may be characterized directly in solution. A conformational search for GB using MacroModel and subsequent DFT optimizations (B3LYP/6-31G(d)) provides a structure for the lowest energy conformer which agrees well with the structure determined by X-ray diffraction. In addition, a conformer at an energy of 7 kJ mol-1 (B3LYP/6-311+G(2d,2p)) with respect to the lowest energy conformer is predicted, displaying different intramolecular hydrogen bonding. Differences between measured and calculated IR and VCD spectra for GB at certain wavenumbers are rationalized in terms of interactions with solvent, intermolecular GB-GB interactions, and the potential presence of more than one conformer. This is the first detailed investigation of the spectroscopic fingerprint region (850-1300 cm-1) of the natural product GB employing infrared absorption and VCD spectroscopy.
U2 - 10.1002/chir.20730
DO - 10.1002/chir.20730
M3 - Journal article
C2 - 19455619
SN - 0899-0042
VL - 22
SP - 217
EP - 223
JO - Chirality
JF - Chirality
IS - 2
ER -