Guga Piotr, Tomaszewska Agnieszka
Centre of Molecular and Macromolecular Studies, Polish Academy of Sciences, Department of Bioorganic Chemistry, Łodź, Poland.
Chirality. 2015 Feb;27(2):115-22. doi: 10.1002/chir.22398. Epub 2014 Nov 18.
A reaction of DBU promoted ring opening in nucleoside-3'-O- and nucleoside-5'-O-(2-thio-4,4-pentamethylene-1,3,2-oxathiaphospholane) monomers with a pyrophosphate or a methylenediphosphonate anion proceeds with substantial loss of stereoselectivity. Depending on the absolute configuration of the phosphorus atom, so far widely accepted the stereoretentive mechanism of condensation is accompanied by a stereoinvertive one, most likely employing an intramolecular ligand-ligand exchange in an uncharged intermediate.
在核苷 - 3'-O- 和核苷 - 5'-O-(2-硫代-4,4-亚戊基-1,3,2-氧杂硫磷杂环戊烷)单体与焦磷酸根或亚甲基二膦酸根阴离子的反应中，DBU促进的开环反应会导致立体选择性大幅丧失。根据磷原子的绝对构型，迄今为止被广泛接受的缩合立体保持机制伴随着立体翻转机制，最有可能是在一个不带电荷的中间体中发生分子内配体 - 配体交换。
