Photocatalytic [2 + 2] Cycloadditions of Enones with Cleavable Redox Auxiliaries
摘要:
alpha,beta-Unsaturated 2-imidazolyl ketones undergo [2 + 2] cycloaddition with a variety of Michael acceptors upon irradiation with visible light in the presence of Ru(bpy)(3)(2+). Cleavage of the imidazolyl auxiliary from the cycloadducts affords cyclobutane carboxamides, esters, thioesters, and acids that would not be accessible from direct cycloaddition of the corresponding unsaturated carbonyl compounds.
Highly Efficient Cyclic Dinucleotide Based Artificial Metalloribozymes for Enantioselective Friedel–Crafts Reactions in Water
作者:Changhao Wang、Min Hao、Qianqian Qi、Jingshuang Dang、Xingchen Dong、Shuting Lv、Ling Xiong、Huanhuan Gao、Guoqing Jia、Yashao Chen、Jörg S. Hartig、Can Li
DOI:10.1002/anie.201912962
日期:2020.2.24
construct artificial metalloenzymes (ArMs) for enantioselective catalysis. DNA-based ArMs containing duplex and G-quadruplex scaffolds have been widely investigated, yet RNA-based ArMs are scarce. Here we report that a cyclic dinucleotide of c-di-AMP and Cu2+ ions assemble into an artificialmetalloribozyme (c-di-AMP⋅Cu2+ ) that enables catalysis of enantioselective Friedel-Crafts reactions in aqueous
Copper‐Catalyzed Asymmetric Conjugate Addition of Dimethylzinc to Acyl‐
<i>N</i>
‐methylimidazole Michael Acceptors: a Powerful Synthetic Platform
作者:Sammy Drissi‐Amraoui、Marie S. T. Morin、Christophe Crévisy、Olivier Baslé、Renata Marcia de Figueiredo、Marc Mauduit、Jean‐Marc Campagne
DOI:10.1002/anie.201506189
日期:2015.9.28
An efficient copper‐catalyzedenantioselectiveconjugateaddition of dimethylzinc to α,β‐ and α,β,γ,δ‐unsaturated 2‐acyl‐N‐methylimidazoles has been achieved using a chiral bidentate hydroxyalkyl‐NHC ligand. The reactions proceeded with both excellent regio‐ and enantioselectivity (14 examples, 87–95 % ee) to afford the desired 1,4‐adducts, which were easily transformed to the corresponding aldehydes
Catalytic enantioselective syn hydration of enones in water using a DNA-based catalyst
作者:Arnold J. Boersma、David Coquière、Danny Geerdink、Fiora Rosati、Ben L. Feringa、Gerard Roelfes
DOI:10.1038/nchem.819
日期:2010.11
The enantioselective addition of water to olefins in an aqueous environment is a common transformation in biological systems, but was beyond the ability of synthetic chemists. Here, we present the first examples of a non-enzymatic catalytic enantioselective hydration of enones, for which we used a catalyst that comprises a copper complex, based on an achiral ligand, non-covalently bound to (deoxy)ribonucleic acid, which is the only source of chirality present under the reaction conditions. The chiral β-hydroxy ketone product was obtained in up to 82% enantiomeric excess. Deuterium-labelling studies demonstrated that the reaction is diastereospecific, with only the syn hydration product formed. So far, this diastereospecific and enantioselective reaction had no equivalent in conventional homogeneous catalysis. Nature frequently shows exquisite control over reactions both of water and in water. Here, the enantioselective conjugate addition of water to an enone â a reaction that has no equivalent in conventional homogeneous catalysis â is catalysed by a copper complex of an achiral ligand that is non-covalently bound to DNA.
在水环境中水与烯烃的对映体选择性加成是生物系统中常见的转化过程,但合成化学家却无法做到。在这里,我们首次展示了烯酮的非酶催化对映体选择性水合反应,为此我们使用了一种催化剂,该催化剂由基于非手性配体的铜络合物组成,铜络合物与(脱氧)核糖核酸非共价结合,而核糖核酸是反应条件下存在的唯一手性来源。手性δ-羟基酮产品的对映体过量率高达 82%。氘标记研究表明,该反应具有非对映特异性,只形成了同步水合产物。迄今为止,这种非对映专一性和对映体选择性反应在传统的均相催化反应中还没有出现过。大自然经常对水和水中的反应进行精妙的控制。在这里,水与烯酮的对映选择性共轭加成反应是由非共价结合到 DNA 上的非手性配体的铜络合物催化的。
Asymmetric synthesis of cyclic β-amino carbonyl derivatives by a formal [3 + 2] photocycloaddition
作者:Leonardo Mollari、Miguel A. Valle-Amores、Ana M. Martínez-Gualda、Leyre Marzo、Alberto Fraile、José Aleman
DOI:10.1039/d1cc05867c
日期:——
reactivity relies on the performance of the substrate-catalyst complex to assist both the enantiocontrol and the photoredox tasks. This transformation led to an enantioselective [3 + 2] photocycloaddition between coordinated α,β-unsaturatedacyl imidazoles and cyclopropylamine derivatives.
Photocatalytic [2 + 2] Cycloadditions of Enones with Cleavable Redox Auxiliaries
作者:Elizabeth L. Tyson、Elliot P. Farney、Tehshik P. Yoon
DOI:10.1021/ol3000298
日期:2012.2.17
alpha,beta-Unsaturated 2-imidazolyl ketones undergo [2 + 2] cycloaddition with a variety of Michael acceptors upon irradiation with visible light in the presence of Ru(bpy)(3)(2+). Cleavage of the imidazolyl auxiliary from the cycloadducts affords cyclobutane carboxamides, esters, thioesters, and acids that would not be accessible from direct cycloaddition of the corresponding unsaturated carbonyl compounds.