Asymmetric Iodoamination of Chalcones and 4-Aryl-4-oxobutenoates Catalyzed by a Complex Based on Scandium(III) and a N,N′-Dioxide Ligand
Asymmetric Iodoamination of Chalcones and 4-Aryl-4-oxobutenoates Catalyzed by a Complex Based on Scandium(III) and a N,N′-Dioxide Ligand
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DOI：
10.1002/chem.201102453
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发表时间：
2011-12-01
影响因子：
4.3
通讯作者：
Feng, Xiaoming
中科院分区：
文献类型：
--
作者：
Cai, Yunfei;Liu, Xiaohua;Feng, Xiaoming
在手性 N,N'-二氧化物/[Sc(OTf)3] 络合物 (0.52 mol%) 存在下，完成了查尔酮、4-芳基-4-氧代丁烯酸酯和三氟取代烯酮的高度非对映和对映选择性碘胺化，得到所需的邻位抗 α-碘-β-氨基羰基 区域选择性地合成高产率（高达 97%）的化合物，并具有出色的非对映选择性（>99:1 d.r.）和对映选择性（高达 99% ee）。对映体纯顺式-α-碘-β-氨基产物也可以通过特定碘化合物的异构化获得。卤源与 TsNH2 反应生成的 TsNHX 物质（X=Cl、Br、I）被进一步证实是参与关键卤离子中间体形成的卤代反应中的活性物质。观察到典型的卤化依赖性，反应性按 NBS>NIS>>NCS 的顺序降低。
Highly diastereo- and enantioselective iodoamination of chalcones, 4-aryl-4-oxobutenoates, and a trifluoro-substituted enone has been accomplished in the presence of a chiral N,N'-dioxide/[Sc(OTf)3] complex (0.52 mol%), delivering the desired vicinal anti-alpha-iodo-beta-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-alpha-iodo-beta-amino products could also be obtained from the isomerization of particular iodo compounds. TsNHX species (X=Cl, Br, I), generated from the reactions between the halo sources and TsNH2, were further confirmed as the active species in the haloamination reactions involved in the formation of the key halonium ion intermediates. A typical haloamination dependency was observed, with reactivity decreasing in the order NBS>NIS >> NCS.