Absolute configuration determination and conformational analysis of (−)-(3<i>S</i>,6<i>S</i>)-3α,6β-diacetoxytropane using vibrational circular dichroism and DFT techniques
作者:Marcelo A. Muñoz、Orlando Muñoz、Pedro Joseph-Nathan
DOI:10.1002/chir.20734
日期:——
considered conformations showed two distinctive spectral ranges, one between 1300 and 1200 cm−1, and the other one in the 1150–950 cm−1 region. When compared with the experimental VCD spectrum, the first spectral region confirmed the calculated conformational preferences, whereas the second region showed little change with conformation, thus allowing the determination of the absolute configuration of 1 as
使用振动圆二色性(VCD)光谱确定了由(-)-6β-羟基hydroxy基胺2制备的半合成(-)-3α,6β-乙酰氧烷1的绝对构型。使用DFT在B3LYP / DGDZVP理论水平上使用DFT计算了八个更稳定的构象异构体的振动光谱(IR和VCD),它们在前10 kcal / mol范围内占总相对丰度的99.97%。计算出的所有已考虑构象的VCD光谱均显示出两个不同的光谱范围,一个在1300至1200 cm -1之间,另一个在1150-950 cm -1之间。地区。与实验VCD光谱相比,第一个光谱区域确认了计算的构象偏好,而第二个区域显示随构象的变化很小,因此可以确定1的绝对构型为(3 S,6 S)-3α,6β ‐diacetoxytropane。此外,第二区域中的条带显示1和2之间的相似性在实验和计算的VCD光谱中,表明这些谱带主要与刚性环烷环系统的绝对构型有关,因为它们显示构象独立性,取代