Tandem Manganese(iii)-Based Oxidative Free-Radical Cyclizations Terminated by Addition to Furans. Formal Synthesis of 15-Acetoxypallescensin-A

Snider, Barry B.; O'Hare, Sean M.

doi:10.1081/scc-100108225

Cited by 13 publications

(8 citation statements)

References 17 publications

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“…As such, the lower cathodic potential decreases the probability of side reactions that may result from the undesirable cathodic reduction of key reaction intermediates or products. In addition, a previous report on relevant radical alkene functionalization reactions showed that TFA may increase the reactivity of manganese …”

Section: Chlorotrifluoromethylationmentioning

confidence: 99%

An Electrocatalytic Approach to the Radical Difunctionalization of Alkenes

2018

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Given its many distinct characteristics, electrochemistry represents an attractive approach to meet the prevailing trends in organic synthesis. In particular, electrocatalysisa process that integrates electrochemistry and small-molecule catalysishas the potential to substantially improve the scope of synthetic electrochemistry and provide a wide range of useful transformations. Recently, we have demonstrated new catalytic approaches that combine electrochemistry and redox-metal catalysis for the oxidative difunctionalization of alkenes to access a diverse array of vicinally functionalized structures. This Perspective details our design principles underpinning the development of electrochemical diazidation, dichlorination, and halotrifluoromethylation of alkenes, which were built on foundational work by others in the areas of synthetic electrochemistry, radical chemistry, and transition-metal catalysis. The introduction of redox-active Mn catalysts allows the generation of radical intermediates from readily available reagents at low potentials under mild conditions. These transition metals also impart selectivity control over the alkene functionalization processes by functioning as radical group transfer agents. As such, our electrocatalytic difunctionalization reactions exhibit excellent chemoselectivity, broad substrate scope, and high functional group compatibility. Specifically, anodically coupled electrolysis, an approach that pairs two single-electron oxidation events in a parallel manner, enables the development of regio- and chemoselective heterodifunctionalization of alkenes. The products of the new transformations we describe in this Perspective represent pertinent structures in numerous medicinally relevant compounds. We anticipate that the design parameters presented here are general and will provide a platform for the development of electrocatalytic systems for other challenging organic redox transformations.

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Section: Chlorotrifluoromethylationmentioning

confidence: 99%

An Electrocatalytic Approach to the Radical Difunctionalization of Alkenes

2018

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“…Tandem processes are thus in line with the principles of green chemistry, [86] and transition elements are frequently involved in tandem oxidation processes, as they often combine different chemical properties acting on different stages of the sequential reactions. [87][88][89][90] Among these elements, manganese is the main topic of numerous publications devoted to tandem oxidation, mainly Mn(III) [91][92][93][94] and Mn(IV). [95][96][97][98] For instance, manganese has recently attracted wide interest for multicomponent reactions based on pincer-type manganese complexes.…”

Section: Tandem Sequential Oxidation Catalyzed By Eco-mn La Andmentioning

confidence: 99%

Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

et al. 2020

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Phytoextraction is one of the most promising phytotechnologies used to restore natural environments degraded by mining activities. In New Caledonia, a few plant species, which belong to the Grevillea genus, have the ability to extract Mn from soil and accumulate it in abundance (over 1 % of leaves dry weight). This review describes the use of Grevillea Mn‐accumulating plant species to produce the first bio‐sourced Mn catalysts, called Eco‐Mn catalysts. Extensive structural studies of Eco‐Mn catalysts have highlighted an original composition characteristic of their vegetal origin. Eco‐Mn catalysts have demonstrated competitive catalytic activities compared to conventional Mn catalysts in Lewis acid catalysis, aminoreductions, alcohol oxidations, epoxidation reactions, oxidative cleavage of 1,2‐diols and alkenes and “Janus catalysts” for sequential tandem oxidations such as tandem carbonyl‐ene cyclisation, synthesis of substituted pyridines and oxidative iodination of ketones.

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“…Transition elements are frequently involved in tandem oxidation processes, as they often combine different chemical properties acting in the different steps of the sequential reaction (Davi and Lebel 2009;Guo et al 2009;Yip et al 2006). Among these elements, manganese is the object of a number of publications devoted to tandem oxidations, mainly with Mn(III) (Li et al 2011;Snider 1996;Snider and O'Hare 2001;Tanyeli et al 2002;Tanyeli and Sezen 2000) and Mn(IV) (McAllister et al 2006;Quesada et al 2006;Quesada and Taylor 2005;Taylor et al 2005).…”

Section: Examples Of Eco-mn 2 -Promoted Oxidationsmentioning

confidence: 99%

“…It has been found to be a mild oxidizing agent with a low reactivity (Cahiez et al 2001a). Application of Mn(III) in organic chemistry has recently emerged, especially in radical reactions (Snider et al 2001). As Mn(II) is considered as a weak Lewis acid (Cahiez et al 2001b), its use in catalysis remains limited.…”

Section: Introductionmentioning

confidence: 99%

Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants

Escande

Renard

Grison

2014

Environ Sci Pollut Res

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Among the phytotechnologies used for the reclamation of degraded mining sites, phytoextraction aims to diminish the concentration of polluting elements in contaminated soils. However, the biomass resulting from the phytoextraction processes (highly enriched in polluting elements) is too often considered as a problematic waste. The manganese-enriched biomass derived from native Mn-hyperaccumulating plants of New Caledonia was presented here as a valuable source of metallic elements of high interest in chemical catalysis. The preparation of the catalyst Eco-Mn1 and reagent Eco-Mn2 derived from Grevillea exul exul and Grevillea exul rubiginosa was investigated. Their unusual polymetallic compositions allowed to explore new reactivity of low oxidative state of manganese-Mn(II) for Eco-Mn1 and Mn(IV) for Eco-Mn2. Eco-Mn1 was used as a Lewis acid to catalyze the acetalization/elimination of aldehydes into enol ethers with high yields; a new green and stereoselective synthesis of (-)-isopulegol via the carbonyl-ene cyclization of (+)-citronellal was also performed with Eco-Mn1. Eco-Mn2 was used as a mild oxidative reagent and controlled the oxidation of aliphatic alcohols into aldehydes with quantitative yields. Oxidative cleavage was interestingly noticed when Eco-Mn2 was used in the presence of a polyol. Eco-Mn2 allowed direct oxidative iodination of ketones without using iodine, which is strongly discouraged by new environmental legislations. Finally, the combination of the properties in the Eco-Mn catalysts and reagents gave them an unprecedented potential to perform sequential tandem oxidation processes through new green syntheses of p-cymene from (-)-isopulegol and (+)-citronellal; and a new green synthesis of functionalized pyridines by in situ oxidation of 1,4-dihydropyridines.

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Tandem Manganese(iii)-Based Oxidative Free-Radical Cyclizations Terminated by Addition to Furans. Formal Synthesis of 15-Acetoxypallescensin-A

Cited by 13 publications

References 17 publications

An Electrocatalytic Approach to the Radical Difunctionalization of Alkenes

An Electrocatalytic Approach to the Radical Difunctionalization of Alkenes

Eco‐Mn Ecocatalysts: Toolbox for Sustainable and Green Lewis Acid Catalysis and Oxidation Reactions

Lewis acid catalysis and Green oxidations: sequential tandem oxidation processes induced by Mn-hyperaccumulating plants

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