Copper‐Catalyzed Difunctionalization of Activated Alkynes by Radical Oxidation–Tandem Cyclization/Dearomatization to Synthesize 3‐Trifluoromethyl Spiro[4.5]trienones

Hua, Hui‐Liang; He, Yu‐Tao; Qiu, Yi‐Feng; Li, Ying-Xiu; Song, Bo; Gao, Pin; Song, Xian‐Rong; Guo, Donghui; Liu, Xueyuan; Liang, Yong‐Min

doi:10.1002/chem.201405672

Cited by 132 publications

(39 citation statements)

References 138 publications

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“…[59] Furthermore,m ore complex cascades were developed along those lines. [60,61] Another beautiful sequence taking advantage of the PRE with peroxyl radicals as in situ generated scavengers is shown in Figure 14 a. Thee sters and amides 44 derived from propiolic acid derivatives and anilines or phenols were used as radical acceptors.I nt he first step,at ransient radical generated by ar edox reaction adds regioselectively to the CÀCt riple bond of 44 to give av inyl radical 45.I ts ipso cyclization onto the arene of the aniline or phenol moiety leads to cyclohexadienyl radical 46,w hich is trapped by tertbutylperoxyl to give peroxide 47,which can undergo aK ornblum-DeLaMare rearrangement [62] to finally provide ketone 48.T his sequence was successfully conducted with various radicals RC using different radical precursors.A lkyl radicals derived from ethers, [63] ketones, [64] or alkanes, [65] acyl radicals from aldehydes, [66] CF 3 radicals from the Langlois reagent, [67] SCF 3 radicals from AgSCF 3 , [68] silyl radicals from silanes, [69] and sulfonyl radicals from sulfonylhydrazides engage in this spirocyclization cascade. [70] Recently,t he groups of Wu and Zhong presented an oxidative cyclization of ethylene-bridged aminoindoles 48 to afford peroxypyrroloindolines 49 with t-BuOOH as the oxidant in combination with TBAI ( Figure 14 b).…”

Section: Alkyl Peroxidesmentioning

confidence: 99%

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The Persistent Radical Effect in Organic Synthesis

2019

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Radical–radical couplings are mostly nearly diffusion‐controlled processes. Therefore, the selective cross‐coupling of two different radicals is challenging and not a synthetically valuable transformation. However, if the radicals have different lifetimes and if they are generated at equal rates, cross‐coupling will become the dominant process. This high cross‐selectivity is based on a kinetic phenomenon called the persistent radical effect (PRE). In this Review, an explanation of the PRE supported by simulations of simple model systems is provided. Radical stabilities are discussed within the context of their lifetimes, and various examples of PRE‐mediated radical–radical couplings in synthesis are summarized. It is shown that the PRE is not restricted to the coupling of a persistent with a transient radical. If one coupling partner is longer‐lived than the other transient radical, the PRE operates and high cross‐selectivity is achieved. This important point expands the scope of PRE‐mediated radical chemistry. The Review is divided into two parts, namely 1) the coupling of persistent or longer‐lived organic radicals and 2) “radical–metal crossover reactions”; here, metal‐centered radical species and more generally longer‐lived transition‐metal complexes that are able to react with radicals are discussed—a field that has flourished recently.

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Section: Alkyl Peroxidesmentioning

confidence: 99%

“…a) Radical spirocyclization with the tert-butylperoxyl radical as atrapping reagent. [63][64][65][66][67][68][69][70] b) Oxidative indole functionalization to access peroxypyrroloindolenines 49. [71] Figure 15.…”

Section: Azaallyl Radicalsmentioning

confidence: 99%

The Persistent Radical Effect in Organic Synthesis

2019

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“…Diese Sequenz wurde mit einer Vielzahl verschiedener Radikale RC durchgeführt. In dieser spiro-Cyclisierung wurden Alkyl-Radikale von Ethern, [63] Ketonen [64] bzw.A lkanen, [65] Acyl-Radikale von Aldehyden, [66] CF 3 -Radikale vom Langlois-Reagenz, [67] SCF 3 -Radikale vom AgSCF 3 , [68] Silyl-Radikale von Silanen [69] und Sulfonyl-Radikale von Sulfonylhydraziden [70] eingesetzt.…”

Section: Alkyl-peroxideunclassified

Der “Persistent Radical Effect” in der organischen Chemie

2019

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Radikal‐Radikal‐Kupplungen sind nahezu diffusionskontrollierte Prozesse. Daher sind selektive Kreuzkupplungen zweier unterschiedlicher Radikale schwierig zu realisieren und stellen somit synthetisch nicht wertvolle Prozesse dar. Wenn die beiden Radikale allerdings eine unterschiedliche Lebensdauer aufweisen und in gleichen Raten gebildet werden, wird die Kreuzkupplung zum dominierenden Prozess. Die hohe Kreuzselektivität basiert auf einem kinetischen Phänomen, dem “Persistent Radical Effect” (PRE). In diesem Aufsatz wird eine von Simulationen einfacher Modellsysteme gestützte Erklärung des PRE geliefert. Weiter werden die Stabilität von Radikalen in Bezug auf ihre Lebensdauer und verschiedene Beispiele für PRE‐vermittelte Radikal‐Radikal‐Kupplungen in der Synthese diskutiert. Es wird gezeigt, dass der PRE nicht auf Kupplungen persistenter mit transienten Radikalen beschränkt ist. Der PRE mit einhergehender hoher Kreuzselektivität greift bereits, wenn ein Kupplungspartner langlebiger als das andere transiente Radikal ist. Diese Tatsache erweitert signifikant das Anwendungsgebiet PRE‐vermittelter Radikalchemie. Dieser Aufsatz ist in zwei Teile aufgeteilt: 1) die Kupplung persistenter oder langlebiger organischer Radikale und 2) Radikal‐Metall‐Kreuzungsreaktionen; hierbei werden Metall‐zentrierte Radikalspezies oder allgemeiner langlebige Übergangsmetallkomplexe, welche mit Radikalen reagieren, diskutiert – ein Gebiet, das jüngst stark expandiert ist.

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“…[31] The scope of the conversion is illustrated in Scheme 22. [31] The scope of the conversion is illustrated in Scheme 22.…”

Section: Carbotrifluoromethylation Of Alkynesmentioning

confidence: 99%

Recent Developments in the Trifluoromethylation of Alkynes

Gao

Song

Liu

et al. 2015

Chemistry A European J

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157

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In the last few years, the development of versatile methodologies to incorporate trifluoromethyl groups into organic molecules has attracted significant attention in synthetic chemistry. This review gives an overview over the development on the trifluoromethylation of alkynes, which have not been solely discussed before. Formation of diverse C(sp, sp(2) , sp(3) )-CF3 bonds are all covered in this review.

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Copper‐Catalyzed Difunctionalization of Activated Alkynes by Radical Oxidation–Tandem Cyclization/Dearomatization to Synthesize 3‐Trifluoromethyl Spiro[4.5]trienones

Cited by 132 publications

References 138 publications

The Persistent Radical Effect in Organic Synthesis

The Persistent Radical Effect in Organic Synthesis

Der “Persistent Radical Effect” in der organischen Chemie

Recent Developments in the Trifluoromethylation of Alkynes

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