Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide

Triandafillidi, Ierasia; Kokotou, Maroula G.; Lotter, Dominik; Sparr, Christof; Kokotos, Christoforos G.

doi:10.1039/d1sc02360h

Cited by 32 publications

(17 citation statements)

References 60 publications

(30 reference statements)

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“…A proposed reaction mechanism for this aerobic and lightpromoted transformation is shown in Scheme 3. Based on previous reports on the catalyst-free aerobic oxidation of aldehydes to carboxylic acids, [15][16][17][18][19][20][21] as well as our previous work on oxidative processes, 27 the starting aldehyde is transformed to the corresponding acyl radical I in the presence of air. This process is spontaneous in the presence of air, 16,17,27 while lit-erature suggests an acceleration of the process in the presence of water.…”

Section: Resultsmentioning

confidence: 99%

Light-promoted oxidation of aldehydes to carboxylic acids under aerobic and photocatalyst-free conditions

et al. 2022

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Section: Resultsmentioning

confidence: 99%

Light-promoted oxidation of aldehydes to carboxylic acids under aerobic and photocatalyst-free conditions

et al. 2022

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“…There are different routes for the synthesis of epoxides, such as oxidation of alkenes [35] or the reaction of alkenes with peroxides [36,37] or often supported by catalysts [1,7]. The epoxidation of allyl alcohols with peroxides leads to important raw materials for the production of glycerol and is also used as a precursor to many specialized compounds, such as flame-resistant materials, drying oils and plasticizers [38].…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Details of the Sharpless Epoxidation of Allylic Alcohols—A Combined URVA and Local Mode Study

Freindorf

Kraka

2022

Catalysts

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In this work, we investigated the catalytic effects of a Sharpless dimeric titanium (IV)–tartrate–diester catalyst on the epoxidation of allylalcohol with methyl–hydroperoxide considering four different orientations of the reacting species coordinated at the titanium atom (reactions R1–R4) as well as a model for the non-catalyzed reaction (reaction R0). As major analysis tools, we applied the URVA (Unified Reaction Valley Approach) and LMA (Local Mode Analysis), both being based on vibrational spectroscopy and complemented by a QTAIM analysis of the electron density calculated at the DFT level of theory. The energetics of each reaction were recalculated at the DLPNO-CCSD(T) level of theory. The URVA curvature profiles identified the important chemical events of all five reactions as peroxide OO bond cleavage taking place before the TS (i.e., accounting for the energy barrier) and epoxide CO bond formation together with rehybridization of the carbon atoms of the targeted CC double bond after the TS. The energy decomposition into reaction phase contribution phases showed that the major effect of the catalyst is the weakening of the OO bond to be broken and replacement of OH bond breakage in the non-catalyzed reaction by an energetically more favorable TiO bond breakage. LMA performed at all stationary points rounded up the investigation (i) quantifying OO bond weakening of the oxidizing peroxide upon coordination at the metal atom, (ii) showing that a more synchronous formation of the new CO epoxide bonds correlates with smaller bond strength differences between these bonds, and (iii) elucidating the different roles of the three TiO bonds formed between catalyst and reactants and their interplay as orchestrated by the Sharpless catalyst. We hope that this article will inspire the computational community to use URVA complemented with LMA in the future as an efficient mechanistic tool for the optimization and fine-tuning of current Sharpless catalysts and for the design new of catalysts for epoxidation reactions.

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“…Since 2013, our group has introduced in literature a novel and green synthetic protocol for oxidation reactions, utilizing 2,2,2‐trifluoroacetophenone as the catalyst and H 2 O 2 as the oxidant [21,22] . Among them, our laboratory has developed a green organocatalytic protocol for the epoxidation of alkenes, [21c] which has been employed for the synthesis of many classes of compounds, [21] while very recently, we expanded the armbox of organocatalytic oxidations, introducing the first catalytic epoxidation of alkenes, using an aldehyde as the catalyst and hydrogen peroxide as the oxidant [21k] . Thus, we became interested in combining the green epoxidation protocol we have introduced and the reaction with thiourea, in order to provide a fast and easy‐to‐operate protocol for the synthesis of thiiranes from alkenes (Scheme 1H).…”

Section: Introductionmentioning

confidence: 99%

Organocatalytic Synthesis of Thiiranes from Alkenes

2022

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Thiiranes, the corresponding sulfur analogues of epoxides, are less studied and less encountered in literature. This might be due to the limited existing synthetic approaches for their synthesis. Herein, a mild, sustainable and efficient organocatalytic synthesis of thiiranes has been developed. Starting from olefins and utilizing the epoxidation protocol developed in the Kokotos’ group, which employs 2,2,2‐trifluoroacetophenone as the organocatalyst and H2O2 as the oxidant, followed by ring opening by thiourea, a variety of thiiranes were synthesized. Both aromatic and aliphatic moieties are well tolerated, leading to thiiranes in moderate to excellent yields.

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Aldehyde-catalyzed epoxidation of unactivated alkenes with aqueous hydrogen peroxide

Abstract: The organocatalytic epoxidation of unactivated alkenes using aqueous hydrogen peroxide provides various indispensable products and intermediates in a sustainable manner. While formyl functionalities typically undergo irreversible oxidations when activating an...

Cited by 32 publications

References 60 publications

Light-promoted oxidation of aldehydes to carboxylic acids under aerobic and photocatalyst-free conditions

Light-promoted oxidation of aldehydes to carboxylic acids under aerobic and photocatalyst-free conditions

Mechanistic Details of the Sharpless Epoxidation of Allylic Alcohols—A Combined URVA and Local Mode Study

Organocatalytic Synthesis of Thiiranes from Alkenes

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