Synthetic Utility of the Captodative Effect

Stella, Lucien; Harvey, Jeremy N.

doi:10.1002/9783527618293.ch18

Cited by 7 publications

(4 citation statements)

References 90 publications

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“…The competition between ET and the C–S bond fragmentation pathways (B and C, respectively), could be measured by the 6 : 7 ratio, and followed the order: CN: 1; Cl: 2; OMe: 10. This trend agrees with the stability order of the distonic radical anions 20a – d , the Cl and CN derivatives being further stabilised by a captodative effect 49, 50…”

Section: Resultssupporting

confidence: 85%

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Wenk

Sander

2001

Chem. Eur. J.

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The matrix isolation and spectroscopic characterization of two C6F4 isomers, the perfluorinated o-benzyne 4 and the m-benzyne 5, is reported. UV photolysis of tetrafluorophthalic anhydride 6 in solid argon at 10 K results in the formation of CO, CO2, and 1,2-didehydro-3,4,5,6-tetrafluorobenzene (4) in a clean reaction. On subsequent 350 nm irradiation 4 is carbonylated to give the cyclopropenone 7. 1,3-Didehydro-2,4,5,6-tetrafluorobenzene (5) was synthesized by UV irradiation of 1,3-diiodo-2,4,5,6-tetrafluorobenzene (8) via 2,3,4,6-tetrafluoro-5-iodophenylradical 9. Photolysis of 8 in solid neon at 3 K produces good yields of both radical 9 and benzyne 5, while in argon at 10 K no reaction is observed. Thus, the photochemistry in neon at extremely low temperature markedly differs from the photochemistry in argon. The formation of 5 from 8 via 9 is reversible, and annealing the neon matrix at 8 K leads back to the starting material 8. The benzynes 4 and 5 and the radical 9 were characterized by comparison of their matrix IR spectra with density functional theory (DFT) calculations.

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Section: Resultssupporting

confidence: 85%

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Wenk

Sander

2001

Chem. Eur. J.

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“…This trend agrees with the stability order of the distonic radical anions 20a-d, the Cl and CN derivatives being further stabilised by a captodative effect. [49,50] The results obtained for the photostimulated reaction of anion 3d with the aryl substrates are mechanistically interesting. [51] In these reactions, the fragmentation step was the most favoured pathway.…”

Section: Mechanistic Considerationmentioning

confidence: 99%

Reactivity of 2‐aryl‐1,3‐dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an S_RN1 mechanism

Oksdath‐Mansilla

Peñéñory

2011

J of Physical Organic Chem

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The reactions of 2‐(4‐Z‐phenyl)‐1,3‐dithiane anions (Z = H, OMe, Cl, CN) with neopentyl, neophyl and phenyl iodides were studied in DMSO, taking into consideration the effect of the Z substituent on the dithiane anions reactivity as well as on the product distribution. These substitution reactions proceed by an SRN1 mechanism with radicals and radical anions as intermediates. Two competitive pathways are possible for the radical anion of the substitution product, namely electron transfer (ET) to the substrate giving the substitution product and C–S bond fragmentation to yield a distonic radical anion. ET is the main pathway for the reactions between dithiane anions bearing electron‐donor substituents and neopentyl or its analogue iodides affording the substitution products in moderate yields (41–53%). Copyright © 2011 John Wiley & Sons, Ltd.

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“…4 Precise understanding of the captodative effect is still lacking and therefore can only be rationalized by its involvement in new reactions. 5 Molecular oxygen is the most inexpensive and ubiquitous reagent for oxidations. While these reactions are thermodynamically favorable, the kinetic inertness of 3 O 2 has hampered its use in synthesis.…”

mentioning

confidence: 99%

“…Despite being known for decades, hard evidence validating this textbook chemistry was only recently reported . Precise understanding of the captodative effect is still lacking and therefore can only be rationalized by its involvement in new reactions …”

mentioning

confidence: 99%

Generation and Aerobic Oxidation of Azavinyl Captodative Radicals

Aggarwal,

Richards,

Fokin

2023

J. Am. Chem. Soc.

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We describe a cascade reaction that selectively incorporates oxygen into the carbon−carbon backbone of alkynes using air as the source. The process starts by lithiating readily available, electron-deficient 1,2,3-triazoles, resulting in an amphoteric lithium ketenimine intermediate. This intermediate can react with both electrophiles and nucleophiles. Under the conditions outlined in this study, we generate azavinyl radicals, which are a rare subset of captodative radicals. When exposed to atmospheric oxygen, these radicals efficiently transform into α-oxygenated amidines�a class of compounds that has not been extensively studied. This process uniquely utilizes molecular oxygen without requiring metal or photocatalysts, and it occurs under mild conditions. Our mechanistic studies provide insights into the intricate sequence involved in the formation and selective capture of azavinyl captodative radicals.

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Synthetic Utility of the Captodative Effect

Cited by 7 publications

References 90 publications

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Reactivity of 2‐aryl‐1,3‐dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an S_RN1 mechanism

Generation and Aerobic Oxidation of Azavinyl Captodative Radicals

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Synthetic Utility of the Captodative Effect

Cited by 7 publications

References 90 publications

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Matrix Isolation and Spectroscopic Characterization of Perfluorinatedortho- andmeta-Benzyne

Reactivity of 2‐aryl‐1,3‐dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an SRN1 mechanism

Generation and Aerobic Oxidation of Azavinyl Captodative Radicals

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Reactivity of 2‐aryl‐1,3‐dithiane anions towards neopentyl, neophyl and phenyl iodides. New evidence for an S_RN1 mechanism