Screening of ligands in the asymmetric metallocenethiolatocopper(I)-catalyzed allylic substitution with Grignard reagents
作者:Hanna K. Cotton、Jakob Norinder、Jan-E. Bäckvall
DOI:10.1016/j.tet.2006.03.100
日期:2006.6
Screening of metallocenethiolate ligands for copper(I)-catalyzed substitution of allylic acetates with Grignard reagents has been carried out. The previously used ligand, lithium (R,Sp)-2-(1-dimethylaminoethyl)ferrocenylthiolate (4a), possessing both central and planar chirality, was the starting point for the screening. It was found that the diastereomeric ligand lithium (R,Rp)-2-(1-dimethylamino
已经进行了用格氏试剂对铜(I)催化的烯丙基乙酸酯取代的金属茂硫醇盐配体的筛选。先前使用的具有中心和平面手性的配体锂(R,S p)-2-(1-二甲基氨基乙基)二茂铁硫醇锂(4a)是筛选的起点。已发现,显示出相反的平面手性的非对映体配体锂(R,R p)-2-(1-二甲基氨基乙基)二茂铁基硫醇锂(4b),至少当使用乙酸肉桂酯作为底物时,在烯丙基取代中增加了对映选择性。钌茂金属基配体锂(R,S p)-2-(1-二甲基氨基乙基)钌烯基硫醇盐(4c)提高了反应速率,但手性诱导降低。使用二硫化物双[(R,S p)-2-(1-二甲基氨基乙基)二茂铁基]二硫化物(7a)作为配体前体效果很好,但对映选择性较低。