Syntheses of C1-symmetric bidentate ligands having pyridyl and 1,3-Thiazolyl, 1-methylimidazolyl or pyrazinyl donor groups for enantioselective palladium-catalyzed allylic substitution and copper-catalyzed cyclopropanation |
| |
| Authors: | Pang-Fei Teng Ho-Lun Yeung Wing-Tak Wong |
| |
| Institution: | a Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
b Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong SAR, China |
| |
| Abstract: | New chiral C1-symmetric bidentate ligands, which possess two different nitrogen heterocycles, 1,3-thiazolyl, 1-methylimidazolyl or pyrazinyl and one pyridyl group, were prepared by Kröhnke condensation in 36-59% overall yield. Stable Pd(II)-allyl and Cu(II) chloride complexes formed by some of the ligands were obtained in 60-65% yields. X-ray crystal structure analysis of a copper(II) complex having 1-methylimidazolyl group indicated that it is a μ-chloro bridge dimer. The Pd(II)-allyl complexes were found to be active catalysts in the asymmetric allylic substitution of 1,3-diphenylprop-2-enyl acetate. The best result observed was 85% e.e. and 99% isolated yield. In addition, the in situ generated Cu(OTf)2 complexes were found to be active catalysts in cyclopropanation of styrene with ethyl diazoacetate. |
| |
| Keywords: | Pyridyl Allylic Substitution Cyclopropanation Palladium Copper |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
