Are the absolute configurations of 2-(1-hydroxyethyl)-chromen-4-one and its 6-bromo derivative determined by X-ray crystallography correct? A vibrational circular dichroism study of their acetate derivatives
作者:Frank J. Devlin、Philip J. Stephens、Pascale Besse
DOI:10.1016/j.tetasy.2005.02.033
日期:2005.4
The vibrational circular dichroism (VCD) spectra of the acetate derivative, 3, of 2-(1-hydroxyethyl)-chromen-4-one, 1, and the acetate derivative, 4, of 6-bromo-2-(1-hydroxyethyl)-chromen-4-one, 2, in the CO stretching region are reported. Density functional theory (DFT) predictions of the VCD spectra of the CO stretching modes of (R)-3 and (R)-4 are in excellent agreement with the experimental spectra
该乙酸酯衍生物,所述的振动圆二色性(VCD)谱3,2-(1-羟乙基) -苯并吡喃-4-酮,1,和乙酸酯衍生物,4,6-溴-2-(1-羟基乙基的报道了在CO拉伸区域中的)-铬-4--4-酮2。(R)-3和(R)-4的CO拉伸模式的VCD光谱的密度泛函理论(DFT)预测与(+)- 3和(+)- 4的实验光谱非常吻合,表明两个分子的绝对构型是(R)-(+)/(S)-(-)。由于(+)- 1和(+)- 2的乙酰化会产生(+)- 3和(+)- 4,因此,这两个1都将导致(R)-(+)/(S)-(-)和2。预先使用X射线晶体学确定(-)- 1和(-)- 2的绝对构型分别为R和S。我们的结果得出这样的结论,即先前报告的绝对配置1不正确。