Asymmetric Iodoamination of Chalcones and 4-Aryl-4-oxobutenoates Catalyzed by a Complex Based on Scandium(III) and a N,N′-Dioxide Ligand
作者:Yunfei Cai、Xiaohua Liu、Jun Li、Weiliang Chen、Wentao Wang、Lili Lin、Xiaoming Feng
DOI:10.1002/chem.201102453
日期:2011.12.23
has been accomplished in the presence of a chiral N,N′‐dioxide/[Sc(OTf)3] complex (0.5–2 mol %), delivering the desired vicinal anti‐α‐iodo‐β‐amino carbonyl compounds regioselectively in high yields (up to 97 %) and with excellent diastereoselectivities (>99:1 d.r.) and enantioselectivities (up to 99 % ee). Enantiopure syn‐α‐iodo‐β‐amino products could also be obtained from the isomerization of particular
查尔酮,4-芳基-4-氧代丁烯酸酯和三氟取代的烯酮的高度非对映和对映选择性碘化已在手性N,N'-二氧化物/ [Sc(OTf)3 ]络合物(0.5– 2 mol%),以高收率(高达97%),高非对映选择性(> 99:1 dr)和对映选择性(高达99%ee)选择性地提供所需的邻位抗α-碘-β-氨基羰基化合物 。对映体纯的顺-α-碘-β-氨基产物也可以通过特定碘化合物的异构化获得。TsNHX物种(X = Cl,Br,I),由卤素源和TsNH 2之间的反应产生在关键的卤代离子中间体形成过程中,被进一步确认为卤化反应中的活性物种。观察到典型的卤化依赖性,反应性按NBS> NIS≫NCS的顺序降低。