The deprotonation of differently substituted propargyl xylosides with s-BuLi/TMEDA followed by protonation with t-butanol at −115 °C provided a range of new axially chiral 1,3-disubstituted alkoxyallenes in a diastereoselective way. Numerous reaction parameters such as solvent, temperature, or protonating agent were examined as well as protecting groups on the xyloside moiety and the influence of the substituents on the alkyne part. The configuration of the main diastereoisomer of 3-methyl-1-xyloside-allene was determined for the first time by single-crystal X-ray diffraction analysis and nOe NMR experiments. Furthermore, DFT calculations on the propargyl/allenyl lithium intermediates formed in the course of the deprotonation reaction provided new structural insights of these complexes. The subsequent protonation process with alcohols was investigated by theoretical surface exploration, revealing the importance of the approach of the alcohol toward the lithium compounds on the reaction outcome.

中文翻译：

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轴向手性木糖衍生的1,3-二取代的烷氧基丙二烯的非对映选择性合成：范围，结构和机理。

用s -BuLi / TMEDA对不同取代的炔丙基木糖苷进行质子化，然后用t进行质子化-115℃下的叔丁醇以非对映选择性的方式提供了一系列新的轴向手性1,3-二取代的烷氧基丙二烯。检查了许多反应参数，例如溶剂，温度或质子化剂，以及木糖苷部分上的保护基以及取代基对炔烃部分的影响。通过单晶X射线衍射分析和nOe NMR实验首次确定了3-甲基-1-木糖苷-丙二烯的主要非对映异构体的构型。此外，对在去质子化反应过程中形成的炔丙基/烯丙基锂中间体的DFT计算提供了这些配合物的新结构见解。通过理论表面探索研究了随后的醇质子化过程，