Regio- and Enantioselective Catalytic Monoepoxidation of Conjugated Dienes: Synthesis of Chiral Allylic <i>cis</i>-Epoxides

Jat, Jawahar L.; De, Saroj Ranjan; Kumar, Ganesh; Adebesin, Adeniyi Michael; Gandham, Shyam K.; Falck, John R.

doi:10.1021/acs.orglett.5b00281

Cited by 21 publications

(8 citation statements)

References 70 publications

(74 reference statements)

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“…In other words, allylic hydroxyl groups may coordinate to the Nb anion in some forms first. To the best of our knowledge, in other catalytic systems such as methyltrioxorhenium (MTO), , dimethyl dioxirane (DMD), m -chloroperbenzoic acid ( m -CPBA), POMs, W complexes, ,, and Ti–substrate systems, two interaction forms, such as hydrogen bonds and metal–alcoholate bonds, have been postulated. Consequently, here we have systematically investigated the epoxidation process of allylic alcohols by [Nb(O-O) 2 (OOH) 2 ] − in hydrogen bonding and metal–alcoholate bonding mechanisms, respectively, aiming to shed light on the favored reaction mechanism and demonstrate the catalytic activity from a theoretical perspective.…”

Section: Results and Discussionmentioning

confidence: 99%

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

et al. 2016

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This work reports new kinds of monomeric peroxoniobate anion functionalized ionic liquids (ILs) designated as [A+][NbO(O-O)(OH)2] (A+ = tetrapropylammonium, tetrabutylammonium, or tetrahexylammonium cation), which have been prepared and characterized by elemental analysis, HRMS, NMR, IR, TGA, etc. With hydrogen peroxide as an oxidant, these ILs exhibited excellent catalytic activity and recyclability in the epoxidation of various allylic alcohols under solvent-free and ice bath conditions. Interestingly, subsequent activity tests and catalyst characterization together with first-principles calculations indicated that the parent [NbO(O-O)(OH)2]− anion has been oxidized into the anion [Nb(O-O)2(OOH)2]− in the presence of H2O2, which constitutes the real catalytically active species during the reaction; this anion has higher activity in comparison to the analogous peroxotungstate anion. Moreover, the epoxidation process of the substrate (allylic alcohol) catalyzed by [Nb(O-O)2(OOH)2]− was explored at the atomic level by virtue of DFT (density functional theory) calculations, identifying that it is more favorable to occur through a hydrogen bond mechanism, in which the peroxo group of [Nb(O-O)2(OOH)2]− serves as the adsorption site to anchor the substrate OH group by forming a hydrogen bond, while OOH as the active oxygen species attacks the CC bond in substrates to produce the corresponding epoxide. This is the first example of the highly efficient epoxidation of allylic alcohols using a peroxoniobate anion as a catalyst.

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Section: Results and Discussionmentioning

confidence: 99%

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

et al. 2016

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“…The same catalyst 41 also catalyzed the epoxidation of a series of ( Z )-enol esters to afford the epoxides in high yield with high enantioselectivity ranging from 86 to >99% ee . It is worth noting that catalyst 43a /Ti(O i Pr) 4 (5 mol %) was found to efficiently conduct the monoepoxidation of conjugated dienes, affording the corresponding chiral allylic cis -epoxides (19 examples) with 72–98% ee …”

Section: Asymmetric Epoxidation Reactionsmentioning

confidence: 99%

Catalytic Asymmetric Oxygenations with the Environmentally Benign Oxidants H₂O₂and O₂

2017

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The discovery of simple and efficient catalyst systems for the asymmetric oxofunctionalization of hydrocarbons is a challenging task of catalytic chemistry. In this paper, we give an overview of catalyst systems capable of conducting asymmetric oxygenative transformations of organic molecules and, in line with the major trend to sustainability, relying on green oxidants HO and O as the ultimate oxygen source. The full historical period of asymmetric oxidation catalysis (1970 to the present day) is covered; both transition-metal-based and organocatalytic systems are considered. The focus of this review is the catalytic properties of the existing catalyst systems, in particular stereoselectivity, activity, efficiency, and synthetic outlook. At the same time, mechanistic peculiarities of stereoselective oxygen transfer are given attention.

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“…Recently, Falck and co‐workers reported that Ti–salan complex 7 is able to catalyze distal selective epoxidation of conjugated dienes even in the presence of other olefins and adjacent stereocenters (Scheme ) . In this context, a variety of well‐established methods for asymmetric epoxidation were surveyed for the regioselective epoxidation of conjugated dienes.…”

Section: Metal‐catalyzed Asymmetric Epoxidation Using Hydrogen Peroxmentioning

confidence: 99%

Asymmetric Epoxidation Using Hydrogen Peroxide as Oxidant

Wang

Yamamoto

2015

Chemistry An Asian Journal

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Asymmetric epoxidation is one of the most important transformations in organic synthesis. Although tremendous progress was achieved in this field in the 1980s and 1990s, it is still desirable from both economical and ecological views to develop environmentally friendly catalytic epoxidation with a broad substrate scope. Hydrogen peroxide is a safe and cheap oxidant, which is easy to handle and generates water as the sole byproduct. Therefore, asymmetric epoxidation of olefins using hydrogen peroxide as oxidant has been a very active research field and has been investigated by many research groups in recent years. In this review, the exciting very recent developments of this rapidly growing area are surveyed and organized according to the catalyst systems.

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Regio- and Enantioselective Catalytic Monoepoxidation of Conjugated Dienes: Synthesis of Chiral Allylic cis-Epoxides

Cited by 21 publications

References 70 publications

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

Catalytic Asymmetric Oxygenations with the Environmentally Benign Oxidants H₂O₂and O₂

Asymmetric Epoxidation Using Hydrogen Peroxide as Oxidant

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Regio- and Enantioselective Catalytic Monoepoxidation of Conjugated Dienes: Synthesis of Chiral Allylic cis-Epoxides

Cited by 21 publications

References 70 publications

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

Highly Efficient Epoxidation of Allylic Alcohols with Hydrogen Peroxide Catalyzed by Peroxoniobate-Based Ionic Liquids

Catalytic Asymmetric Oxygenations with the Environmentally Benign Oxidants H2O2and O2

Asymmetric Epoxidation Using Hydrogen Peroxide as Oxidant

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Catalytic Asymmetric Oxygenations with the Environmentally Benign Oxidants H₂O₂and O₂