Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Chemical Reviews, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 13, 2024

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. iodine are commonly used synthetically important halogenations, oxidations, aminations, heterocyclizations, various oxidative functionalizations of substrates. Iodonium salts arylating reagents, while iodonium ylides imides excellent carbene nitrene precursors. Various derivatives benziodoxoles, such azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, alkenylbenziodoxoles group transfer the presence transition metal catalysts, under metal-free conditions, or using photocatalysts photoirradiation conditions. Development hypervalent catalytic systems discovery highly enantioselective reactions chiral represent a particularly recent achievement field chemistry. Chemical transformations promoted by many cases unique cannot be performed any other common, non-iodine-based reagent. This review covers literature published mainly last 7-8 years, between 2016 2024.

Language: Английский

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Catalyst-Substrate Helical Character Matching Determines the Enantioselectivity in the Ishihara-Type Iodoarenes Catalyzed Asymmetric Kita-Dearomative Spirolactonization

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(13), P. 7301 - 7312

Published: March 20, 2023

Catalyst design has traditionally focused on rigid structural elements to prevent conformational flexibility. Ishihara's elegant of conformationally flexible C2-symmetric iodoarenes, a new class privileged organocatalysts, for the catalytic asymmetric dearomatization (CADA) naphthols is notable exception. Despite widespread use Ishihara catalysts CADAs, reaction mechanism remains subject debate, and mode induction not been well established. Here, we report an in-depth computational investigation three possible mechanisms in literature. Our results, however, reveal that this best rationalized by fourth called "proton-transfer-coupled-dearomatization (PTCD)", which predicted be strongly favored over other competing pathways. The PTCD consistent with control experiment further validated applying it rationalize enantioselectivities. Oxidation I(I) catalyst active I(III) species induces defined helical chiral environment delicate balance between flexibility rigidity. A match/mismatch effect substrate's shape transition states was observed. match allows adapt its conformation maximize attractive noncovalent interactions, including I(III)···O halogen bond, N-H···O hydrogen π···π stacking, stabilize state. stereochemical model capable rationalizing variation enantioselectivities developed. present study enriches our understanding how achieve high stereoinduction may serve as inspiration future exploration designs.

Language: Английский

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Iodanes as multi-tools for the total synthesis of complex natural products

Chemical Communications, Journal Year: 2023, Volume and Issue: 59(43), P. 6495 - 6508

Published: Jan. 1, 2023

Hypervalent iodine reagents are among the most fascinating described in last 30 years since they allow a plethora of different transformations and environmentally friendly compounds that avoid use toxic heavy metals cases. Hence, their versatility has been widely used multi-step syntheses for formation complex structures. In particular, iodanes can easily generate complexity from simple substrates, leading to polyfunctionalized systems rapid natural products or related intricate architectures. this review, we describe recent routes strategies produce based on several key steps mediated by hypervalent iodines help building desired molecule framework, highlighting numerous advantages these reactants yet not hiding possible limitations.

Language: Английский

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Homogeneous and heterogeneous reaction mechanisms of synthetic phenolic antioxidants and their environmental effects

Journal of environmental chemical engineering, Journal Year: 2025, Volume and Issue: unknown, P. 116256 - 116256

Published: March 1, 2025

Language: Английский

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Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies

Chemistry - A European Journal, Journal Year: 2024, Volume and Issue: 30(20)

Published: Feb. 7, 2024

Abstract The electrochemical oxidative dearomatizing methoxylation of phenols and naphthols was developed. It provides an alternative route for the preparation methoxycyclohexadienones, important versatile synthetic intermediates, that eliminates need stoichiometric high‐energy chemical oxidants generates hydrogen as a sole by‐product. reaction proceeds in simple constant current mode, undivided cell, it employs standardized instrumentation. A collection methoxycyclohexadienones derived from various 2,4,6‐tri‐substituted 1‐substituted‐2‐naphthols obtained moderate to excellent yields. These include complex derivative estrone, well methoxylated dearomatized 1,1′‐bi‐2‐naphthols (BINOLs). mechanism subject profound investigations using density functional theory calculations. In particular, reactivity two key phenoxyl radical phenoxenium ion, carefully examined. results shed light on pathway leading desired product rationalize experimentally observed selectivities regarding side benzylic preference functionalization at para over ortho position. They also uncover structure‐selectivity relationship, inversely correlating steric bulk substrate with its propensity undergo side‐reaction. Moreover, loss stereochemical information enantiopure BINOL substrates during is rationalized by computations.

Language: Английский

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Mechanistic Insight into Phenol Dearomatization by Hypervalent Iodine: Direct Detection of a Phenoxenium Cation

The Journal of Organic Chemistry, Journal Year: 2022, Volume and Issue: 87(21), P. 14274 - 14283

Published: Oct. 10, 2022

Phenol dearomatization is one of several oxidation reactions enabled by hypervalent iodine reagents. However, the presence a proposed free phenoxenium intermediate in phenol matter debate literature. Here, we report unambiguous detection reaction an electron-rich phenol, 2,4,6-trimethoxyphenol, and (diacetoxyiodo)benzene using UV–vis resonance Raman spectroscopies. In contrast, predominantly detect single electron products less phenols or alkoxy-substituted aromatics their with paramagnetic (EPR) We conclude that often-postulated intermediate, while possible highly stabilizing substituents, unlikely to be general mechanistic pathway typical The polar solvent 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) use more strongly oxidizing reagents, such as [bis(trifluoroacetoxy)iodo]benzene (PIFA) [hydroxy(tosyloxy)iodo]benzene (HTIB), can help reduce formation radical byproducts favors intermediates.

Language: Английский

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Structure Elucidation of In Situ Generated Chiral Hypervalent Iodine Complexes via Vibrational Circular Dichroism (VCD)

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(50)

Published: May 16, 2022

The structure of in situ generated chiral aryl-λ3 -iodanes obtained under oxidative reaction conditions was not yet observable with experimental techniques and their proposed structures are purely based on DFT calculations. Herein, we establish vibrational circular dichroism (VCD) spectroscopy as an technique to verify DFT-calculated iodane structures. Based a triazole-substituted iodoarene catalyst, were able elucidate undescribed cationic the most populated intermediate significant intramolecular N-I-interaction no interactions tosylate or m-chlorobenzoic acid potential anionic ligands. Instead, aggregation these substrates found, which resulted formation non-coordinating hydrogen bonded complex. importance VCD crucial is further highlighted by fact that our initial structural proposal, calculations, could be falsified.

Language: Английский

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para-Selective dearomatization of phenols by I(i)/I(iii) catalysis-based fluorination

Chemical Science, Journal Year: 2023, Volume and Issue: 14(46), P. 13574 - 13580

Published: Jan. 1, 2023

The regio- and enantio-selective dearomatization of phenols has been achieved by I(i)/I(iii) catalysis enabled fluorination. process is highly para-selective, guiding the fluoride nucleophile to distal C4 position substrate generate fluorinated cyclohexadienones in an operationally simple manner. Extensive optimization revealed key parameters that orchestrate enantioselectivity this historically challenging transformation. A range diversely substituted substrates are disclosed (20 examples, up 92 : 8 e.r.) reaction displays efficiency competitive with current state art hydroxylation chemistry: provides a preparative platform enable OH F bioisosterism be explored. Finally, utility products accessing densely functionalized cyclic scaffolds five contiguous stereocenters together crystallographic analyses unveil fluorine-carbonyl non-covalent interactions.

Language: Английский

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Synthesis of Pummerer’s ketone and its analogs by iodosobenzene-promoted oxidative phenolic coupling

Tetrahedron Letters, Journal Year: 2020, Volume and Issue: 61(43), P. 152459 - 152459

Published: Sept. 16, 2020

Language: Английский

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Electrophile–Arene Affinity: An Energy Scale for Evaluating the Thermodynamics of Electrophilic Dearomatization Reactions

The Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 89(16), P. 11487 - 11501

Published: July 30, 2024

Rational design and development of organic reactions are lofty goals in synthetic chemistry. Quantitative description the properties molecules by physical parameters plays an important role this regard. In Article, we report energy scale, namely, electrophile-arene affinity (EAA), for evaluating thermodynamics electrophilic dearomatization reactions, a class transformations that can rapidly build up molecular complexity structural diversity converting planar aromatic compounds into three-dimensional cyclic molecules. The acquisition EAA data be readily achieved theoretically calculating enthalpy changes (Δ

Language: Английский

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