Stereochemistry of the [2+2] Cycloaddition of Chlorosulfonyl Isocyanate to Chiral Alkoxyallenes Derived from 1,3-Alkylidene-L-erythritol and -D-threitol
作者:Tong�Thanh Danh、Wojciech Bocian、Lech Kozerski、Patrycja Szczukiewicz、Jadwiga Frelek、Marek Chmielewski
DOI:10.1002/ejoc.200400557
日期:2005.1
The [2+2] cycloaddition of chlorosulfonyl isocyanate to alkoxyallenes derived from ethylidene and benzylidene erythritols and threitols proceeds with a moderate asymmetric induction in the case of the erythritols and with a very low induction in the case of threitols. This indicates that the erythritol derivatives may exist in solution in one predominant conformation while the threitol derivatives
氯磺酰基异氰酸酯与衍生自亚乙基和亚苄基赤藓糖醇和苏糖醇的烷氧基丙二烯的 [2+2] 环加成在赤藓糖醇的情况下以适度的不对称诱导进行,在苏糖醇的情况下以非常低的诱导进行。这表明赤藓糖醇衍生物可能以一种主要构象存在于溶液中,而苏糖醇衍生物表现为一种构象集合。烷氧基丙二烯的构象通过各种 NMR 技术以及从头计算进行研究。由此获得的结果与我们基于环加成立体选择性的预测完全一致。通过环加成获得的氮杂环丁酮在氮原子处进行分子内烷基化以提供相应的三环头孢菌素。所得氮杂环丁酮和头孢菌素的绝对构型使用 NMR 和 CD 光谱进行分配。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)