Wang F, Wang H, Polavarapu P L, Rizzo C J
Department of Chemistry, Vanderbilt University, Nashville, TN 37235, USA.
J Org Chem. 2001 May 18;66(10):3507-12. doi: 10.1021/jo0100401.
Enantiopure (+)-2,5-dimethylthiolane and (-)-2,5-dimethylsulfolane were prepared using literature procedures and investigated using vibrational circular dichroism (VCD). Experimental absorption and VCD spectra of (+)-2,5-dimethylthiolane and (-)-2,5-dimethylsulfolane in CCl(4) solution in the 2000-900 cm(-)(1) region were compared with the ab initio predictions of absorption and VCD spectra obtained with density functional theory using the B3LYP/6-311G(2d, 2p) basis set for different conformers of (2R,5R)-2,5-dimethylthiolane and (2R,5R)-2,5-dimethylsulfolane. This comparison indicates that (+)-2,5-dimethylthiolane is of the (2R,5R)-configuration and has two predominant conformations in CCl(4) solution. In addition, (-)-2,5-dimethylsulfolane is of (2R,5R)-configuration and has only one predominant conformation. The stereochemical assignment is in agreement with literature.
对映体纯的(+)-2,5-二甲基硫杂环戊烷和(-)-2,5-二甲基环丁砜采用文献方法制备，并使用振动圆二色性(VCD)进行研究。将(+)-2,5-二甲基硫杂环戊烷和(-)-2,5-二甲基环丁砜在CCl₄溶液中2000 - 900 cm⁻¹区域的实验吸收光谱和VCD光谱，与使用密度泛函理论、B3LYP/6 - 311G(2d, 2p)基组对(2R,5R)-2,5-二甲基硫杂环戊烷和(2R,5R)-2,5-二甲基环丁砜不同构象得到的吸收光谱和VCD光谱的从头算预测结果进行比较。该比较表明，(+)-2,5-二甲基硫杂环戊烷具有(2R,5R)-构型，且在CCl₄溶液中有两种主要构象。此外，(-)-2,5-二甲基环丁砜具有(2R,5R)-构型，且只有一种主要构象。立体化学归属与文献一致。
