Dynamic Ligand Exchange of the Lanthanide Complex Leading to Structural and Functional Transformation: One-Pot Sequential Catalytic Asymmetric Epoxidation-Regioselective Epoxide-Opening Process
摘要:
The characteristic property of the lanthanide complex, which easily undergoes a dynamic ligand exchange and alters its structure and function in situ, is described. After the completion of the catalytic asymmetric epoxidation of various a,beta-unsaturated amides 2 in the presence of the Sm-(S)-BINOL-Ph3As=O (1:1:1) complex 1 (2-10 mol %), the addition of Me3SiN3 directly to the reaction mixture led to smooth epoxide-opening at room temperature, affording the corresponding anti-beta-azido-alpha-hydroxyamide 4 in excellent overall yield (up to 99%) with complete regioselectivity and excellent enantiomeric excess (up to >99%). The key to the success of the sequential process was the in situ generation of the highly reactive samarium azide complex through dynamic ligand exchange. In situ IR spectroscopy and other experiments provided strong evidence that the samariurn azide complex was generated. In addition, the relatively high Lewis basicity of the amide moiety had a key role in the high reactivity of both the epoxidation and the epoxide-opening reactions. Examinations of other nucleophiles such as sulfur or carbon nucleophiles as well as transformations of epoxide-opened products are also described.
Manganese-Promoted Regioselective Ring-Opening of 2,3-Epoxy Acid Derivatives: A New Route to α-Hydroxy Acid Derivatives
作者:José M. Concellón、Pablo L. Bernad、Humberto Rodríguez-Solla、Pamela Díaz
DOI:10.1002/adsc.200900257
日期:2009.9
amides as starting materials, the corresponding 3-aryl-2-hydroxy amides in enantiopure form are also available. Some synthetic applications of selected examples of 3-aryl-2-hydroxy carboxylic acidderivatives are shown. A mechanism has been proposed to explain this novel reaction.
Manganese Catalyzed Enantioselective Epoxidation of
<i>α</i>
,
<i>β</i>
‐Unsaturated Amides with H
<sub>2</sub>
O
<sub>2</sub>
作者:Roman V. Ottenbacher、Vladimir I. Kurganskiy、Evgenii P. Talsi、Konstantin P. Bryliakov
DOI:10.1002/adsc.202100198
日期:2021.6.8
Herewith, we report the enantioselectiveepoxidation of electron-deficient cis- and trans-α,β-unsaturated amides with the environmentally benign oxidant H2O2. The catalysts - manganese complexes with bis-amino-bis-pyridine and structurally related ligands - exhibit reasonably high efficiency (up to 100 TON) and excellent chemo- and enantioselectivity (up to 100% and 99% ee, respectively). Crucially
在此,我们报告了缺电子顺式和反式-α,β-不饱和酰胺与环境友好型氧化剂H 2 O 2的对映选择性环氧化反应。催化剂——锰与双氨基双吡啶和结构相关配体的配合物——表现出相当高的效率(高达 100 吨)和优异的化学和对映选择性(分别高达 100% 和 99% ee)。至关重要的是,顺式-enamides环氧化的对映选择性和产率用NH部分的存在,其效果可以通过之间的氢键相互作用来解释被显着增强的顺-烯酰胺底物和锰基氧转移物质。
Catalytic asymmetric epoxidation of α,β-unsaturated carboxylic acid imidazolides and amides by lanthanide–BINOL complexes
Highly enantioselective catalytic asymmetric epoxidation of α,β-unsaturatedcarboxylic acid imidazolides and simple amides was developed. In the presence of 5–10 mol% of lanthanide–BINOL complexes, the reaction proceeded smoothly with high substrate generality. In particular, in the cases of α,β-unsaturated amides, there was nearly perfect enantioselectivity (>99% ee). The corresponding epoxides were
Asymmetric Epoxidation vs <i>syn</i>-Hydroxy-Acyloxylation of Olefins in the Presence of Sterically Demanding Nonheme Manganese Complexes
作者:Varvara A. Sherstyuk、Roman V. Ottenbacher、Evgenii P. Talsi、Konstantin P. Bryliakov
DOI:10.1021/acscatal.3c04832
日期:2024.1.5
Herewith, we present another facet of the versatile catalytic reactivity of bulky bis-amino-bis-pyridylmethyl Mn complexes: besides highly enantioselective (up to 99% ee) epoxidation, benzhydryl-substituted Mn catalysts have been found to convert olefinic substrates into the products of syn-addition to the C═C bond, hydroxy-carboxylates, that can prevail under certain conditions. The mechanism of