Chiral bis(2-oxazolinyl)xanthene (xabox)/transition-metal complexes catalyzed 1,3-dipolar cycloaddition reactions and Diels–Alder reactions
作者:Kesiny Phomkeona、Toshihide Takemoto、Yosuke Ishima、Kazutaka Shibatomi、Seiji Iwasa、Hisao Nishiyama
DOI:10.1016/j.tet.2007.11.109
日期:2008.2
A series of chiral 4,5-bis(2-oxazolinyl)-(2,7-di-tert-butyl-9,9-dimethyl)-9H-xanthenes (xabox) and their transition-metal complexes were synthesized. The X-ray analysis of xabox–RhCl3 complex shows a unique facial type structure. Xabox–Bn–Mn(II) and xabox–Bn–Mg(II) complexes were found to be efficient catalysts in nitrone 1,3-dipolar cycloaddition (1,3-D.C.) reaction resulting in good to excellent
合成了一系列手性的4,5-双(2-恶唑啉基)-(2,7-二叔丁基-9,9-二甲基)-9 H-黄嘌呤(xabox)及其过渡金属配合物。Xabox–RhCl 3复合物的X射线分析显示出独特的面部类型结构。发现Xabox–Bn–Mn(II)和xabox–Bn–Mg(II)配合物是硝酮1,3-偶极环加成(1,3-DC)反应的有效催化剂,对映选择性优良,极佳,范围从96: 4至> 99:图10F内型/外型比和91-96%ee的对内切加合物。硝酮1,3-DC反应中配体的对映体过量与产物之间的相关性显示出明显的线性关系,这表明xabox-金属催化剂可以用作单分子催化剂。此外,还发现xabox - i -Pr-Mn(II)配合物是丙烯酰恶唑烷酮与环戊二烯Diels-Alder(D-A)反应的活性催化剂,定量提供了相应的环加合物,ee和98%对应,98 :2内/外比。