Ferrosalen and Ferrosalen-Type Ligands: Structural Modulation and Applications in Asymmetric Catalysis

Several ferrosalen and ferrosalen-type ligands, 1−10, were prepared and fully characterized. The structure of one of these ligands ligated to Cu(II) was determined by single-crystal X-ray diffraction analysis. In comparison with the parent ligand 1, the two six-membered rings of ligand 2 are not aromatized and the synthesis was more facile. Diastereoisomers 3 and 4, containing substituents on the ethylene chain, were synthesized. The aromatized versions of 3 and 4, namely 5 and 6, were also prepared. Further modulation of the ethylene backbone produced ligands 7 and 8. Replacing the Cp ligands with Cp* and CpPh5 gave ligands 9 and 10, respectively. All these ligands were tested for catalytic asymmetric reactions, including the Co(III)-catalyzed carbonyl-ene reaction, Al(III)-catalyzed Strecker reaction, and Al(III)-catalyzed silylcyanation of aldehyde.我们制备了编号为1−10的若干铁salen配体（ferrosalen）及铁salen型配体（ferrosalen-type ligands），并对其进行了全面表征。通过单晶X射线衍射分析，解析了其中一个与Cu(II)配位的配体的晶体结构。与母体配体1相比，配体2的两个六元环未发生芳构化，且其合成更为简便。我们合成了在乙烯链上带有取代基的非对映异构体3和4，对应的芳构化版本5和6也同样被制备得到。对乙烯骨架进行进一步修饰，得到配体7和8。将Cp配体分别替换为Cp*和CpPh5，即可得到配体9和10。我们对所有上述配体开展了催化不对称反应测试，测试涵盖Co(III)催化的羰基-烯反应、Al(III)催化的斯特雷克反应（Strecker reaction）以及Al(III)催化的醛硅氰化反应。