A new phosphoramiditeligand was used in the iridium-catalyzed allylicsubstitution reaction. This permitted high regio- and enantioselectivities on a wide variety of substrates and nucleophiles. Because of the stereospecificity of the reaction obtained by using branched substrates, a kinetic resolution reaction was attempted. The origin of the impressive efficiency of this ligand in terms of kinetics
作者:Can-Can Bao、Dong-Song Zheng、Xiao Zhang、Shu-Li You
DOI:10.1021/acs.organomet.8b00762
日期:2018.12.24
N-Heterocyclic carbenes (NHCs) were found to be suitable ligands in Ir-catalyzed intermolecular allylic alkylation reaction. In the presence of a catalyst derived from [Ir(dncot)Cl]2 (dncot = dinaphthocyclooctatetraene) and triazolium salt L7, the alkylation products from the reaction of aryl allyl carbonates with sodium dialkyl malonates could be obtained in 85–99% yields favoring the formation of
发现N-杂环卡宾(NHC)是Ir催化的分子间烯丙基烷基化反应中的合适配体。在[Ir(dncot)Cl] 2(dncot =二萘环辛酸酯四烯)和三唑鎓盐L7衍生的催化剂存在下,芳基烯丙基碳酸酯与二烷基丙二酸钠的反应可得到烷基化产物,收率高达85-99%,形成支链产物(90/10→> 99/1 b / l)。此外,手性二氢异喹啉型NHC(DHIQ-NHC)(L8)已成功应用于Ir催化的不对称烯丙基烷基化反应中。对于广泛的底物,获得了优异的对映选择性和中等的区域选择性。
Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxides: DIAPHOXs. Formal enantioselective synthesis of (−)-paroxetine
An Ir-catalyzed asymmetric allylic alkylation using chiral diaminophosphine oxide is described. Asymmetric allylic alkylation of terminal allylic carbonates proceeded using 5 mol % of Ir catalyst, 5 mol % of DIAPHOX 1i, 10 mol % of NaPF6, 10 mol % of LiOAc, and N,O-bis(trimethylsilyl)acetamide (BSA), affording the corresponding branched products in excellent yield and in up to 95% ee. The developed
well-defined tridentate chiral sulfoxide-N-olefin ligand has been designed and applied in rhodium-catalyzed asymmetric allylicsubstitutions of racemic allyliccarbonates, providing the branched allylic products in good yields with good to high enantioselectivities and excellent regioselectivities. This reaction mechanism, which involves the possible hemilability of olefin coordination on sulfoxide-N-olefin