New chiral iodooxazoline catalysts for the I(III)-mediated α-tosyloxylation of ketones: refining the stereoinduction model

Thérien, Marie-Ève; Guilbault, Audrey-Anne; Legault, Claude Y.

doi:10.1016/j.tetasy.2013.08.002

Cited by 29 publications

(12 citation statements)

References 26 publications

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“…Based on these advantages, it is surprising that pseudocyclic N‐heterocycle‐stabilized iodanes (NHIs) have been only rarely described (Figure B). In recent examples, chiral oxazoline‐ and pyridine‐modified aryl iodides as well as the oxidized λ 3 ‐ and λ 5 ‐iodanes have been described by Birmann, Legault, and Wirth . Even though these heterocyclic substitutions lead to enhanced reactivities and stereoselectivities in oxidative transformations, a direct interaction of the nitrogen atom with the hypervalent iodine center could not be ascertained.…”

Section: Figurementioning

confidence: 99%

“…In recent examples, chiral oxazoline-and pyridine-modified aryl iodides as well as the oxidized l 3 -a nd l 5 -iodanes have been described by Birmann, Legault, and Wirth. [21,[24][25][26][27][28] Even thought heseh eterocyclic substitutions lead to enhanced reactivities and stereoselectivities in oxidative transformations, ad irect interaction of the nitrogen atom with the hypervalent iodine center could not be ascertained. (2-Pyridinyl)-substituted aryl-l 3 -iodane 7,d iscovered by MuÇiz and co-workers, was the first example in which ad irectN ÀIi nteraction wasc onfirmed using X-ray structurea nalysis for an N-heterocyclic substituent.…”

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confidence: 99%

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N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

Boelke

Lork

Nachtsheim

2018

Chemistry A European J

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Pseudocyclic aryl‐λ3‐iodanes are superior reagents for a variety of oxidative transformations due to a well‐balanced relation between stability, solubility and reactivity. Their properties are substantially influenced by a dative interaction between a Lewis base, in general the oxygen atom of a carboxylic acid or an amide, and the central hypervalent iodine atom. This work presents the first systematic investigation of pseudocyclic N‐heterocycle‐stabilized iodanes (NHIs). The synthesis of these throughout shelf‐stable solids is robust and can be achieved on a large scale. Their reactivity is highly tunable, depending on the stabilizing heterocycle. Solid state structures of selected derivatives are reported and their reactivity in a model oxygen transfer reaction is compared. Further derivatization reactions to N‐heterocycle‐stabilized pseudocyclic diaryliodonium salts and cyclic iodoso species are presented as well.

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Section: Figurementioning

confidence: 99%

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confidence: 99%

N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

Boelke

Lork

Nachtsheim

2018

Chemistry A European J

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“…This dramatically enhances reactivity by accelerating further ligand exchange processes and favoring the final reductive collapse of the iodine(III) into its monovalent iodine(I) state within the final oxidative coupling step. Based on this so‐called “hypervalent twist”, chiral iodoarene pre‐catalysts were designed employing an ortho ‐oxazoline moiety, with the p ‐chloro derivative 2 being the most efficient . A similar reactivity enhancing effect was observed for the o ‐Me‐substituted iodoarene catalyst 3 by Whitehead and co‐workers .…”

Section: Introductionmentioning

confidence: 79%

Evolution of N‐Heterocycle‐Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)‐Mediated Oxidative Transformations

Boelke

Nachtsheim

2019

Adv Synth Catal

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The reactivity of ortho‐functionalized N‐heterocycle‐substituted iodoarenes (NHIAs) as organocatalysts in iodine(I/III)‐mediated oxidations was systematically investigated in the α‐tosyloxylation of ketones as the model reaction. During a systematic catalyst evolution, it was found that NH‐triazoles and benzoxazoles have the most significant positive influence on the reactivity of the central iodine atom. A further catalyst improvement which focused on the substitution pattern of the arene revealed a remarkable ortho‐effect. By introduction of an o‐OMe group we were able to generate a novel NHIA with a so far unseen catalytic efficiency. This new catalyst is not only easy to synthesize but also enabled the α‐tosyloxylation of carbonyl compounds at the lowest reported catalyst loading of only 1 mol%. Finally, the performance of this iodine(I) catalyst was successfully demonstrated in intramolecular oxidative couplings of biphenyls and oxidative rearrangements.

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“…Koser et al have reported the α ‐tosyloxylation for the first time using [hydroxy(tosyloxy)iodo]benzene (HTIB), which is also called as Koser's reagent as shown in Scheme . Following the seminal contribution by Wirth et al on the asymmetric α ‐tosyloxylation reactions, substantial efforts have been made toward the development of enantioselective version of these reactions. In 2007, Wirth et al developed the first enantioselective α ‐tosyloxylation of ketones catalyzed by chiral iodoarene using m ‐CPBA as a terminal oxidant …”

Section: α‐Functionalization Of Carbonyl Compoundsmentioning

confidence: 99%

Hypercoordinate iodine(III) promoted reactions and catalysis: an update on current mechanistic understanding

Sreenithya

Surya

Sunoj

2017

WIREs Comput Mol Sci

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Mild and environment friendly hypercoordinate iodine compounds exhibit promising reactivities resembling that of transition metal catalysts. Hypercoordinate iodine reagents or catalysts are increasingly been employed in contemporary organic synthesis. However, mechanistic insights on such reactions continue to remain rather limited. Recent advances in the mechanistic understanding on a selected set of reactions involving hypercoordinate iodine form the main theme of this review. An overview of bonding, reactivity, and mechanistic insights on iodine(III) reactions such as α-functionalization of carbonyl compounds, alkynylation, amination, C H functionalization, phenol dearomatization, and trifluoromethylation have been described. In keeping with the current practices in mechanistic studies, we have maintained an interdisciplinary flavor in this compilation by providing a balanced view of computational and experimental understanding on the burgeoning domain of hypercoordinate iodine mediated reactions and catalysis. FIGURE 1 | Molecular orbital (MO) diagram for three-center-fourelectron (3c-4e) bond in hypercoordinate iodine compound RIL 2 . SCHEME 1 (a) General representation of α-tosyloxylation ketone catalyzed by Koser's reagent. (b) General mechanism for the α-tosyloxylation ketone. (c) Commonly employed iodoarenes in α-tosyloxylation. Overview wires.wiley.com/compmolsci SCHEME 2 (a) Effect of different substituents on the catalytic activity of iodoaryl in α-tosyloxylation. (b) Effect of different substituents on dihedral angle θ(C1-C2-I3-O4). (c) Formation of iodono intermediate 4 and the related ΔG rxn . WIREs Computational Molecular Science Hypercoordinate iodine(III) promoted reactions and catalysis Volume 7,

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New chiral iodooxazoline catalysts for the I(III)-mediated α-tosyloxylation of ketones: refining the stereoinduction model

Cited by 29 publications

References 26 publications

N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

Evolution of N‐Heterocycle‐Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)‐Mediated Oxidative Transformations

Hypercoordinate iodine(III) promoted reactions and catalysis: an update on current mechanistic understanding

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