Conformational Flexibility of Corey Lactone Derivatives Indicated by Absorption and Vibrational Circular Dichroism Spectra

Infrared absorption and vibrational circular dichroism (VCD) spectra of four Corey lactone
derivatives (diol, benzoate, p-phenylbenzoate, and bisbenzoate) were measured and analyzed on
the basis of ab initio computations. The analysis interpreted most of the spectral features as well
as the differences among individual compounds. Despite the common rigid lactone residue,
conformational behaviors and spectral features of the derivatives were found to be different, because
of hydrogen bonding and solvent effects. Recognition of common molecular parts in the spectra of
different molecules increases the potential of using VCD for monitoring the purity of intermediates
in chiral syntheses. For the derivatives, a conserved spectral component corresponding to the lactone
skeleton could be identified on the basis of theoretical analysis but was relatively weak in intensity.

本研究对四种科里内酯（Corey lactone）衍生物（即二醇、苯甲酸酯、对苯基苯甲酸酯与二苯甲酸酯）的红外吸收光谱与振动圆二色性（Vibrational Circular Dichroism，VCD）光谱进行了测量，并基于从头算（ab initio）计算开展了分析。本次分析对绝大多数光谱特征以及各化合物间的光谱差异均作出了解释。尽管此类衍生物均带有共同的刚性内酯残基，但受氢键作用与溶剂效应的影响，不同衍生物的构象行为与光谱特征仍存在显著差异。识别不同分子光谱中共有的分子结构片段，可提升VCD在手性合成中间体纯度监测中的应用潜力。通过理论分析，可在该类衍生物的光谱中识别出与内酯骨架对应的保守光谱组分，但其信号强度相对较弱。