Nucleophilic substitution in iodonium derivatives of indole

Ermolenko, M. S.; Budylin, V. A.; Кост, А. Н.

doi:10.1007/bf00471643

Cited by 10 publications

(8 citation statements)

References 2 publications

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“…Moreover, radical pathways have also been implicated in reactions involving iodonium with nucleophiles such as 2‐nitropropanate anion via a single electron transfer mechanism . It has also been suggested that, under specific conditions, aryliodonium iodide decomposed in part via a radical pathway . However, the hypothesis of a free radical reaction was ruled out by comparing the reaction rate in the presence of atmospheric oxygen (standard conditions of this study), in the absence of oxygen (solvent degassed under argon), and in the presence of a radical scavenger (TEMPO).…”

Section: Resultsmentioning

confidence: 99%

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Guérard

Lee

Baidoo

et al. 2016

Chemistry A European J

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Aryliodonium salts have become precursors of choice for the synthesis of 18F-labelled tracers for nuclear imaging. However little is known on the reactivity of these precursors with heavy halogenides, i.e. radioiodide and astatide at the radiotracer scale. Herein, we report the first comparative study of radiohalogenation of aryliodonium salts with [125I]-iodide and [211At]-astatide. Initial experiments on a model compound highlight a higher reactivity of astatide compared to iodide that could not be anticipated from the trends previously observed within the halogen series. Kinetic studies indicate a significant difference in activation energy (Ea = 23.5 and 17.1 kcal/mol with 125I− and 211At−, respectively). Quantum chemical calculations support the hypothesis of a monomeric iodonium-astatide intermediate whereas radio-iodination occurs in a dimeric environment. The good to excellent regioselectivity of halogenation and high yields achieved with diversely substituted aryliodonium salts indicates that this class of compounds is a promising alternative to the stannane chemistry currently used for radiohalogen labeling of tracers in nuclear medicine.

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Section: Resultsmentioning

confidence: 99%

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Guérard

Lee

Baidoo

et al. 2016

Chemistry A European J

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“…[37] It has also been pointed out that under specific conditions, aryliodonium iodide decomposed in part via a radical pathway. [13,38] However, the hypothesis of a free radical reaction was ruled out by comparing the reaction rate in the presence of atmospheric oxygen (standard conditions of this study), in the absence of oxygen (solvent degassed under argon) and in the presence of a radical scavenger (TEMPO). In all three cases, reaction rates and products formed were essentially identical (Table S3).…”

Section: Thermochemical and Quantum Chemical Studiesmentioning

confidence: 99%

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Guérard

Lee

Baidoo

et al. 2016

Chemistry A European J

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What is the most significant result of this study?Astatine is definitely ah alogen apart and it was demonstrated again in this study.B ecause it is too rare to observe and analyze by conventional approaches, chemists have tried for decades to anticipate its reactivity by extrapolation from its closest neighbor, iodine, but experiments frequently proved these predictions wrong. In this study,w ei nitially anticipated the nucleophilic substitution of astatide on aryliodonium salts to occur similarly to iodide. However,w eobserved ar eactivity that was much higher.Quantum chemical calculations were then utilized to propose mechanisms for this reactivity since astatine is "invisible"; it is available only at the nanogram scale at best. These observations make diaryliodonium salts much more useful than expected to synthesize astatinated compounds, especially with the radioisotope

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“…[1][2][3] Our interest in the most numerous member of this group, the diaryliodinium salts, arose as it has been demonstrated that they are suitable precursors for the formation of fluoroarenes by the action of fluoride ion. 4,5 We have extended this methodology to the introduction of the fluorine-18 label (t1 2 = 109.7 min) in the form of [ 18 F]fluoride. 6,7 This reagent has distinct advantages over the standard electrophilic procedures, which employ molecular [ 18 F]F 2 and derived reagents, as it is produced in higher amounts and higher specific radioactivity by several orders of magnitude.…”

Section: Theoretical Prediction That the Nucleophilic Substitution Of...mentioning

confidence: 99%

Fluoridation of heteroaromatic iodonium salts—experimental evidence supporting theoretical prediction of the selectivity of the process

Martín‐Santamaría

Carroll

et al. 2000

Chem. Commun.

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Nucleophilic substitution in iodonium derivatives of indole

Cited by 10 publications

References 2 publications

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Unexpected Behavior of the Heaviest Halogen Astatine in the Nucleophilic Substitution of Aryliodonium Salts

Fluoridation of heteroaromatic iodonium salts—experimental evidence supporting theoretical prediction of the selectivity of the process

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