Electrochemical reduction of some hypervalent iodine compounds

Kokkinidis, G.; Hatzigrigoriou, Evangelia; Sazou, Dimitra; Varvoglis, Anastasios

doi:10.1016/0013-4686(91)85324-z

“…The calculated endergonicity for initiation by PIDAHFIP is in excellent agreement with that measured for trans anethol 14 (see Figure 3). 43 Following the SEO step the bond length of the acetate group to iodine, namely I⎼O bonds, increases from 2.15 Å to around 2.58 Å for the non-hydrogen bonded PIDA ( Figure S4) and to longer distances of 2.66 Å and 2.78 Å for the hydrogen-bonded PIDAHFIP ( Figure 5) 60 This has been also reported for oxidative of alcohols. 44 The process for 4 + →12 + has a reasonable barrier of 9.0 kcal mol −1 via π-π stacked head-to-head (Figure 5).…”

Section: Mechanism Of Dimerizationsupporting

confidence: 71%

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hussein¹,

Ma²,

Al-Yasari³

2020

Preprint

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<a>A mechanistic insight into </a>the hetero- and homodimerizations (HETD and HOMD) of styrenes promoted by hypervalent iodine reagents (HVIRs; DMP and PIDA) and facilitated by HFIP to yield all trans cyclobutanes is reported using density functional theory (DFT) calculations. The initialization involving direct bimolecular one-electron transfer is found to be highly unfavored, especially for the PIDA system. At this point, we suggest that the reaction is initiated with an overall two-electron reductive cleavage of two I─O bond cleavages, affording I(III) (iodinane) and I(I) (iodobenzene) product with DMP and PIDA as oxidant, respectively. The resulting acetate groups are stabilized by the solvent HFIP through strong hydrogen bonding interaction, which promotes the electron transfer process. The nature of the electron transfer is studied in detail and found that the overall two-electron transfer occurs within tri-molecular complex organized by π-stacking interactions and as a stepwise and concerted mechanism for I(III) and I(V) oxidants, respectively. The reaction rate is determined by the initialization step: for I(III), the initiation is thermodynamically endergonic, whereas the endergonicity for I(V) is modest. Upon initialization, the reaction proceeds through a stepwise [2+2] pathway, involving a radical-cationic π-π stacked intermediate, either hetero- or homodimerized. DFT results supported by quasiclassical molecular dynamics simulations show that HOMD is dynamically competing pathway to HETD although the latter is relatively faster, in accordance with experimental observations.

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“…Reported literatures have shown that I(III), PIDA, undergoes a reductive cleavage of their I-O bonds under to yield the corresponding I(I), namely iodobenzene. 61 This has been also reported for oxidative of alcohols. 44 The process for 4 + →12 + has a reasonable barrier of 9.5 kcal mol −1 via π-π stacked head-to-head (Figure 5).…”

Section: Mechanism Of Dimerizationsupporting

confidence: 63%

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hussein

¹

,

Ma²,

Al-Yasari³

2020

Preprint

0

View full text Add to dashboard Cite

<a>A mechanistic insight into </a>the hetero- and homodimerizations (HETD and HOMD) of styrenes promoted by hypervalent iodine reagents (HVIRs; DMP and PIDA) and facilitated by HFIP to yield all trans cyclobutanes is reported using density functional theory (DFT) calculations. The initialization involving direct bimolecular one-electron transfer is found to be highly unfavored, especially for the PIDA system. At this point, we suggest that the reaction is initiated with an overall two-electron reductive cleavage of two I─O bond cleavages, affording I(III) (iodinane) and I(I) (iodobenzene) product with DMP and PIDA as oxidant, respectively. The resulting acetate groups are stabilized by the solvent HFIP through strong hydrogen bonding interaction, which promotes the electron transfer process. The nature of the electron transfer is studied in detail and found that the overall two-electron transfer occurs within tri-molecular complex organized by π-stacking interactions and as a stepwise and concerted mechanism for I(III) and I(V) oxidants, respectively. The reaction rate is determined by the initialization step: for I(III), the initiation is thermodynamically endergonic, whereas the endergonicity for I(V) is modest. Upon initialization, the reaction proceeds through a stepwise [2+2] pathway, involving a radical-cationic π-π stacked intermediate, either hetero- or homodimerized. DFT results supported by quasiclassical molecular dynamics simulations show that HOMD is dynamically competing pathway to HETD although the latter is relatively faster, in accordance with experimental observations.

show abstract

“…Reported literatures have shown that I(III), PIDA, undergoes a reductive cleavage of their I-O bonds under to yield the corresponding I(I), namely iodobenzene. 60 This has been also reported for oxidative of alcohols. 44 The process for 4 + →12 + has a reasonable barrier of 9.5 kcal mol −1 via π-π stacked head-to-head (Figure 5).…”

Section: Mechanism Of Dimerizationsupporting

confidence: 63%

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerizations Initiation Proceed with Two-Electron Reductive Cleavage

Hussein

¹

,

Al-Yasari²,

Ma³

2020

Preprint

0

View full text Add to dashboard Cite

<a>A mechanistic insight into </a>the hetero- and homodimerizations (HETD and HOMD) of styrenes promoted by hypervalent iodine reagents (HVIRs; DMP and PIDA) and facilitated by HFIP to yield all trans cyclobutanes is reported using density functional theory (DFT) calculations. The reaction is initiated with two-electron reductive cleavage of two I─O bond cleavages, affording I(III) (iodinane) and I(I) (iodobenzene) product with DMP and PIDA as oxidant, respectively. The resulting acetate groups are stabilized by the solvent HFIP through strong hydrogen bonding interaction, which promotes the electron transfer process. The initialization involving one-electron transfer was found to be highly unfavored, especially for the PIDA system. At this point, we found that two-electron process is the key initialization process, which is in accordance with literature report on alcohol oxidation. The reaction rate is determined by the initialization step: For I(III), the initiation is thermodynamically endergonic, whereas the endergonicity for I(V) is modest. The difference in reactivity is explained by the difference LUMO energies. Upon initialization, the reaction proceeds through a stepwise [2+2] pathway, involving a radical-cationic π-π stacked intermediate, either hetero- or homodimerized. DFT results supported by quasiclassical molecular dynamics simulations show that HOMD is dynamically competing pathway to HETD although the latter is relatively faster, in accordance with experimental observations.

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Electrochemical reduction of some hypervalent iodine compounds

Cited by 12 publications

References 12 publications

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerization Initiation Proceeds with Two-Electron Reductive Cleavage

Hypervalent Iodine-Mediated Styrene Hetero- and Homodimerizations Initiation Proceed with Two-Electron Reductive Cleavage

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