Lewis Acid Activation of Fragment-Coupling Reactions of Tertiary Carbon Radicals Promoted by Visible-Light Irradiation of EDA Complexes
作者:Spencer P. Pitre、Tyler K. Allred、Larry E. Overman
DOI:10.1021/acs.orglett.1c00023
日期:2021.2.5
The addition of tertiary carbon radicals generated from N-(acyloxy)phthalimide esters to cyclic α,β-unsaturated ketones and lactones is markedly enhanced by the addition of substoichiometric amounts of a Ln(OTf)3. The reaction is accomplished by irradiation with visible light in the absence of a photosensitizer and is suggested to proceed by excitation of a ternary electron donor–acceptor complex between
Decarboxylative Giese-Type Reaction of Carboxylic Acids Promoted by Visible Light: A Sustainable and Photoredox-Neutral Protocol
作者:Nieves P. Ramirez、Jose C. Gonzalez-Gomez
DOI:10.1002/ejoc.201601478
日期:2017.4.18
for decarboxylative generation of radicals from carboxylicacids and their 1,4-addition to Michael acceptors. The Fukuzumi catalyst ([Acr+-Mes]) enabled this transformation under visiblelight irradiation, at room temperature and with CO2 as the only byproduct. Scope and limitations of this protocol were examined using a range of Michael acceptors (15 examples) and a diverse array of carboxylic acids
这项工作描述了一种无过渡金属的方法,用于从羧酸中脱羧生成自由基及其与迈克尔受体的 1,4-加成。Fukuzumi 催化剂 ([Acr+-Mes]) 在可见光照射下、在室温下和 CO2 作为唯一副产物的情况下实现了这种转变。使用一系列迈克尔受体(15 个示例)和各种羧酸(18 个示例)检查了该协议的范围和限制。在该协议中使用 3-羟基新戊酸允许直接形成非对映异构纯 δ-内酯。此外,当使用高烯丙酸时,会发生自由基级联反应,形成三个 CC 键。
Acridine Photocatalysis: Insights into the Mechanism and Development of a Dual-Catalytic Direct Decarboxylative Conjugate Addition
作者:Hang T. Dang、Graham C. Haug、Vu T. Nguyen、Ngan T. H. Vuong、Viet D. Nguyen、Hadi D. Arman、Oleg V. Larionov
DOI:10.1021/acscatal.0c03440
日期:2020.10.2
Conjugateaddition is one of the most synthetically useful carbon–carbon bond-forming reactions; however, reactive carbon nucleophiles are typically required to effect the addition. Radical conjugateaddition provides an avenue for replacing reactive nucleophiles with convenient radical precursors. Carboxylicacids can serve as simple and stable radical precursors by way of decarboxylation, but activation
Catalyst-Controlled C–H Functionalization of Adamantanes Using Selective H-Atom Transfer
作者:Hai-Bin Yang、Abigail Feceu、David B. C. Martin
DOI:10.1021/acscatal.9b01394
日期:2019.6.7
been developed using photoredox and H atom transfer catalysis. This C–H alkylation reaction has excellent chemoselectivity for the strong 3° C–H bonds of adamantanes in polyfunctional molecules. In substrate competition reactions, a reversal in selectivity is observed for the new H-atom transfer catalyst reported here in comparison to five known photochemical systems. Derivatization of a broad scope
Photo-Mediated Decarboxylative Giese-Type Reaction Using Organic Pyrimidopteridine Photoredox Catalysts
作者:Firas El-Hage、Christopher Schöll、Jola Pospech
DOI:10.1021/acs.joc.0c01955
日期:2020.11.6
The decarboxylativeGiese-typereaction offers a versatile methodology for the radical alkylation of electron-deficient alkenes. Photo-mediated variants often require a pre-activation of carboxylicacids and/or employment of costly transition-metal photocatalysts. Herein, we present a metal-free photocatalyzed decarboxylativeGiese-type addition to electron-deficient alkenes using pyrimidopteridine