Chiral bis(2-oxazolinyl)xanthene (xabox)/transition-metal complexes catalyzed 1,3-dipolar cycloaddition reactions and Diels-Alder reactions |
| |
| Authors: | Kesiny Phomkeona Yosuke Ishima Seiji Iwasa Hisao Nishiyama |
| |
| Institution: | a Department of Materials Science, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku-cho, Toyohashi, Aichi 464-8603, Japan
b Graduate Schools of Engineering, Department of Applied Chemistry, Nagoya University, Chikusa, Nagoya 464-8600, Japan |
| |
| Abstract: | 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 enantioselectivities ranging from 96:4 to >99:1of endo/exo ratio and 91-96% ee for the endo adduct. The correlation between enantiomeric excess of the ligand and the product in the nitrone 1,3-D.C. reaction shows a clear linear relationship, which suggests xabox-metal catalyst worked as a single molecular catalyst. In addition, xabox-i-Pr-Mn(II) complex was also found to be an active catalyst for Diels-Alder (D-A) reaction of acryloyloxazolidinone and cyclopentadiene affording the corresponding cycloadduct in quantitative yield along with 82% ee and 98:2 endo/exo ratio. |
| |
| Keywords: | 1 3-Dipolar cycloaddition Chiral ligand Diels-Alder reaction Oxazoline Xanthene |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
