Brzostowska Edyta M, Paulynice Martine, Bentley Ronald, Greer Alexander
Department of Chemistry and Graduate Center, and The City University of New York (CUNY), Brooklyn College, Brooklyn, New York 11210, USA.
Chem Res Toxicol. 2007 Jul;20(7):1046-52. doi: 10.1021/tx7000465. Epub 2007 Jun 20.
A low-energy pathway for pentathiepin racemization has been found using density functional theory (DFT) calculations. 3-[1,2,3,4,5]pentathiepin-6-yl-propylamine served as a model compound for tunicate-derived pentathiepins. Pentathiepin racemization becomes a low-energy process in the presence of a thiolate ion nucleophile. It is unknown whether the biosynthetic process for pentathiepins is enantiospecific (Bentley, R. (2005) Chem. Soc. Rev. 34, 609) or whether toxicity differs between enantiomers. However, the ease of thiolate ion attack on the polysulfur ring suggests that nucleophiles may induce optical instability on the laboratory time scale. The DFT study predicts that enantiospecific behaviors such as toxicity differences between P- and M-pentathiepins would be difficult to determine experimentally. The computed results fit into a broader picture that nucleophiles assist in ring-opening and equilibration reactions of polysulfanes.
利用密度泛函理论（DFT）计算发现了一种低能量的五硫杂环庚烷消旋化途径。3-[1,2,3,4,5]五硫杂环庚烷-6-基丙胺用作被囊动物来源的五硫杂环庚烷的模型化合物。在硫醇盐离子亲核试剂存在下，五硫杂环庚烷消旋化成为一个低能量过程。五硫杂环庚烷的生物合成过程是否具有对映体特异性（Bentley, R. (2005) Chem. Soc. Rev. 34, 609），或者对映体之间的毒性是否不同尚不清楚。然而，硫醇盐离子对多硫环的攻击容易程度表明，亲核试剂可能在实验室时间尺度上诱导光学不稳定性。DFT研究预测，诸如P-和M-五硫杂环庚烷之间的毒性差异等对映体特异性行为将难以通过实验确定。计算结果符合一个更广泛的情况，即亲核试剂有助于多硫化物的开环和平衡反应。
