Carbon acidity. 70. Equilibrium ion pair acidities in tetrahydrofuran of benzylic carbon acids stabilized by an adjacent cyano, carboalkoxy, and sulfonyl substituent. Delocalization and aggregation of ion pairs

Kaufman, Michael J.; Gronert, Scott; Bors, Daniel A.; Streitwieser, Andrew

doi:10.1021/ja00236a059

Cited by 36 publications

(16 citation statements)

References 4 publications

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“…Table 2 shows that the salts rac ‐ 3 , rac ‐ 4 , rac ‐ 6 , and rac ‐ 9 (entries 1–4) exist in THF at low temperatures as mixtures of monomers and dimers in ratios ranging from 85:15 to 33:67 depending on the substituents on the C α atom (see below). These results are in accordance with those obtained in previous cryoscopy experiments of lithium salts of chiral and achiral α‐sulfonyl carbanions [1c,3f,3g,6k,23] and acidity measurements of sulfones in THF 5a,5d,5g…”

Section: Resultssupporting

confidence: 92%

Experimental and Theoretical Investigation of the Enantiomerization of Lithium α‐tert‐Butylsulfonyl Carbanion Salts and the Determination of Their Structures in Solution and in the Crystal

et al. 2010

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Dynamic NMR (DNMR) spectroscopy of [R 1 C(R 2 )SO 2 R 3 ]Li (R 1 , R 2 = alkyl, phenyl; R 3 = Ph, tBu, adamantyl, CEt 3 ) in [D 8 ]THF has shown that the S-tBu, S-adamantyl, and S-CEt 3 derivatives have a significantly higher enantiomerization barrier than their S-Ph analogues. C α -S bond rotation is most likely the rate-determining step of the enantiomerization of the salts bearing a bulky group at the S atom and two substituents at the C α atom.

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Section: Resultssupporting

confidence: 92%

Experimental and Theoretical Investigation of the Enantiomerization of Lithium α‐tert‐Butylsulfonyl Carbanion Salts and the Determination of Their Structures in Solution and in the Crystal

et al. 2010

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“…Foramore comprehensive discussion of ion-pairing and solvent effects,werefer to several excellent reports. [4,10,[12][13][14]…”

Section: Spectroscopic Properties Of Organic Anionsmentioning

confidence: 99%

“…Upon excitation in polar media, the anionic donor needs to initially encounter a cationic acceptor to trigger the photodecomposition and, hence, increased lifetimes are recorded. For a more comprehensive discussion of ion‐pairing and solvent effects, we refer to several excellent reports [4, 10, 12–14] …”

Section: Introductionmentioning

confidence: 99%

Excited State Anions in Organic Transformations

2020

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Utilizing light is a smart way to fuel chemical transformations as it allows the energy to be selectively focused on certain molecules. Many reactions involving electronically excited species proceed via open‐shell intermediates, which offer novel and unique routes to expand the hitherto used synthetic toolbox in organic chemistry. The direct conversion of non‐prefunctionalized, less activated compounds is a highly desirable goal to pave the way towards more sustainable and atom‐economic chemical processes. Photoexcited closed‐shell anions have been shown to reach extreme potentials in single electron transfer reactions and reveal unusual excited‐state reactivity. It is, therefore, surprising that their use as a reagent or photocatalyst is limited to a few examples. In this Review, we briefly discuss the characteristics of anionic photochemistry, highlight pioneering work, and show recent progress which has been made by utilizing photoexcited anionic species in organic synthesis.

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“…Füre ine detailliertere Diskussion hinsichtlich Ionenpaarungs-und Lçsungsmitteleffekte mçchten wir an dieser Stelle auf hervorragende Übersichts-und Originalartikel verweisen. [4,10,[12][13][14]…”

Section: Introductionunclassified

“…Um die Photozersetzung der Aryldiazoniumverbindung 1 in polarem Medium auszulösen, müssen dissoziierter anionischer Donor 2 und kationischer Akzeptor 1 unmittelbar nach Anregung mit Licht aufeinander treffen, was zu messbaren Fluoreszenzlebensdauern führt. Für eine detailliertere Diskussion hinsichtlich Ionenpaarungs‐ und Lösungsmitteleffekte möchten wir an dieser Stelle auf hervorragende Übersichts‐ und Originalartikel verweisen [4, 10, 12–14] …”

Section: Introductionunclassified

Photoangeregte Anionen in organischen Reaktionen

2020

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Die Durchführung chemischer Reaktionen mit Licht erlaubt es, die eingestrahlte Energie selektiv auf bestimmte Moleküle zu fokussieren. Viele Reaktionen, an denen elektronisch angeregte Spezies beteiligt sind, verlaufen über radikalische Zwischenstufen, die neue, einzigartige Reaktionswege ermöglichen und somit bekannte Syntheserouten zur Umwandlung organischer Moleküle erweitern. Der direkte Einsatz nicht funktionalisierter bzw. reaktionsträger Verbindungen ist ein erstrebenswertes Ziel, um chemische Prozesse nachhaltiger und atomökonomischer gestalten zu können. Es wurde gezeigt, dass angeregte Anionen mit gepaarten Elektronen enorme Potentiale in Elektronentransferreaktionen überwinden können und dass häufig ungewöhnliche Reaktivitäten im angeregten Zustand beobachtbar sind. In diesem Aufsatz fassen wir kurz die Eigenschaften der anionischen Photochemie zusammen, heben die wegweisenden Arbeiten auf diesem Gebiet hervor und diskutieren aktuelle Entwicklungen, die durch photoangeregte anionische Spezies in der organischen Synthese erzielt wurden.

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Carbon acidity. 70. Equilibrium ion pair acidities in tetrahydrofuran of benzylic carbon acids stabilized by an adjacent cyano, carboalkoxy, and sulfonyl substituent. Delocalization and aggregation of ion pairs

Cited by 36 publications

References 4 publications

Experimental and Theoretical Investigation of the Enantiomerization of Lithium α‐tert‐Butylsulfonyl Carbanion Salts and the Determination of Their Structures in Solution and in the Crystal

Experimental and Theoretical Investigation of the Enantiomerization of Lithium α‐tert‐Butylsulfonyl Carbanion Salts and the Determination of Their Structures in Solution and in the Crystal

Excited State Anions in Organic Transformations

Photoangeregte Anionen in organischen Reaktionen

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