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
作者:Pang-Fei Teng、Chui-Shan Tsang、Ho-Lun Yeung、Wing-Leung Wong、Wing-Tak Wong、Hoi-Lun Kwong
DOI:10.1016/j.jorganchem.2006.06.050
日期:2006.12
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
通过Kröhnke缩合反应制备了具有2个不同的氮杂环,1,3-噻唑基,1-甲基咪唑基或吡嗪基和一个吡啶基的新的手性C 1对称双齿配体,总收率为36-59%。由某些配体形成的稳定的Pd(II)-烯丙基和Cu(II)氯化物络合物的收率为60-65%。具有1-甲基咪唑基的铜(II)配合物的X射线晶体结构分析表明它是μ-氯桥二聚体。发现Pd(II)-烯丙基络合物是乙酸1,3-二苯基丙-2-烯基酯的不对称烯丙基取代中的活性催化剂。观察到的最佳结果是85%ee和99%分离产率。另外,原位生成Cu(OTf)2 发现该配合物是苯乙烯与重氮乙酸乙酯进行环丙烷化的活性催化剂。