Comparison of various density functional methods for distinguishing stereoisomers based on computed <sup>1</sup>
H or <sup>13</sup>
C NMR chemical shifts using diastereomeric penam β-lactams as a test set
作者:Keith W. Wiitala、Christopher J. Cramer、Thomas R. Hoye
DOI:10.1002/mrc.2045
日期:2007.10
chemical shift assignments were made for two sets of penam β‐lactams: namely, the diastereomeric (2S, 5S, 6S)‐, (2S, 5R, 6R)‐, (2S, 5S, 6R)‐, and (2S, 5R, 6S)‐methyl 6‐(1,3‐dioxoisoindolin‐2‐yl)‐3,3‐dimethyl‐7‐oxo‐4‐thia‐1‐aza‐bicyclo[3.2.0]heptane‐2‐carboxylates (1–4) and (2S, 5R, 6R)‐, (2S, 5S, 6R)‐, and (2S, 5R, 6S)‐6‐(1,3‐dioxoisoindolin‐2‐yl)‐3,3‐dimethyl‐7‐oxo‐4‐thia‐1‐aza‐bicyclo[3.2.0]heptane‐2‐carboxylic
对两组 Penam β-内酰胺进行了完整的 1H 和 13C NMR 化学位移分配:即非对映异构体 (2S, 5S, 6S)-, (2S, 5R, 6R)-, (2S, 5S, 6R)-, (2S, 5R, 6S)-methyl 6-(1,3-dioxoisoindolin-2-yl)-3,3-二甲基-7-oxo-4-thia-1-aza-bicyclo[3.2.0]heptane- 2-羧酸盐 (1-4) 和 (2S, 5R, 6R)-, (2S, 5S, 6R)-, 和 (2S, 5R, 6S)-6-(1,3-dioxoisoindolin-2-yl)- 3,3-二甲基-7-氧代-4-硫杂-1-氮杂-双环[3.2.0]庚烷-2-羧酸(6-8)。然后将每个 Penam 建模为使用 AMBER* 力场从 Monte Carlo 搜索中获得的一系列构象异构体,然后使用氯仿溶剂化对每个构象异构体进行