Synthesis of chiral salan ligands with bulky substituents and their application in Cu-catalyzed asymmetric Henry reaction
作者:Zhou Wang、Jianghao He、Ying Mu
DOI:10.1016/j.jorganchem.2020.121546
日期:2020.12
Several new chiral N,N’-dimethylated salan ligands with bulky substituents were synthesized and their in-situ generated Cu(II) complexes were evaluated in the asymmetric Henry reaction. Substituents on the aryloxide moieties of these ligands were found to show remarkable effect on the enantioselectivity. Cu(II) complex generated from the ligand with 1,1-diphenylethyl groups at the ortho-position of
合成了几个具有庞大取代基的手性N,N'-二甲基化Salan配体,并在不对称Henry反应中评估了它们的原位生成的Cu(II)配合物。发现这些配体的芳氧基部分上的取代基显示出对映选择性的显着影响。由在芳氧基部分和Cu(OAc)2 ·H 2的邻位具有1,1-二苯乙基的配体生成的Cu(II)络合物发现O显示出良好的催化性能,在-20℃下在THF中在TEA存在下以85%的收率得到94-ee的2-硝基-1-苯基乙醇产物。在存在或不存在TEA的情况下,用不同的醛检查催化剂体系,并以85%至95%ee的高收率(最高94%)获得相应的产物。使用硝基乙烷作为亲核试剂得起非对映选择性反应的顺式- β以良好的收率-nitroalcohols(48%-66%)以良好的博士(高达11.5:1顺式/反)和高EE的值(92%-96%)。