Transition-Metal-Free C–H Hydroxylation of Carbonyl Compounds

Chaudhari, Moreshwar B.; Sutar, Yogesh; Malpathak, Shreyas; Hazra, Anirban; Gnanaprakasam, Boopathy

doi:10.1021/acs.orglett.7b01616

Cited by 74 publications

(88 citation statements)

References 45 publications

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“…It has been proved that the peroxide intermediate was formed during the aerobic hydroxylation of carbonyl compounds [8, 14] . Generally, this intermediate is reduced efficiently by phosphine reductants such as P(OEt) 3 and PPh 3 [7, 9] .…”

Section: Resultsmentioning

confidence: 99%

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene Enhances Activity of Peroxide Intermediates in Phosphine‐Free α‐Hydroxylation of Ketones

et al. 2021

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The critical role of double hydrogen bonds was addressed for the aerobic α‐hydroxylation of ketones catalyzed by 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD), in the absence of either a metal catalyst or phosphine reductant. Experimental and theoretical investigations were performed to study the mechanism. In addition to initiating the reaction by proton abstraction, a more important role of TBD was revealed, that is, to enhance the oxidizing ability of peroxide intermediates, allowing DMSO to be used rather than commonly used phosphine reductants. Further characterizations with nuclear Overhauser effect spectroscopy (NOESY) confirmed the presence of double hydrogen bonds between TBD and the ketone, and kinetic studies suggested the attack of dioxygen on the TBD‐enol adduct to be the rate‐determining step. This work should encourage the application of TBD as a catalyst for oxidations.

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Section: Resultsmentioning

confidence: 99%

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene Enhances Activity of Peroxide Intermediates in Phosphine‐Free α‐Hydroxylation of Ketones

et al. 2021

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“…Because the reaction was performed under inert conditions, exclusive formation of the intermediate D ruled out the water addition across the Ru–alkoxy intermediate I . 12 Allowing the reaction to mix under air generates the intermediates F and G via C–H peroxidation and peroxide cleavage by enolate 13 to afford the product H . The formation of the intermediate G was confirmed by freezing the crude reaction mixture using liquid N 2 followed by immediate injection into a HRMS instrument, which observed the mass value of 294.0537, which corresponds to the intermediate G as a potassium adduct.…”

Section: Results and Discussionmentioning

confidence: 99%

Ru-NHC Catalyzed Domino Reaction of Carbonyl Compounds and Alcohols: A Short Synthesis of Donaxaridine

et al. 2017

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Direct α-alkylation of amides and the synthesis of C3-alkylated 3-hydroxyindolin-2-one/2-substituted-2-hydroxy-3,4-dihydronaphthalen-1(2 H )-one derivatives from 2-oxindole/1-teralone were reported using primary alcohols in the presence of Ru-NHC catalyst in a one pot condition under the borrowing hydrogen method. In the case of inert conditions, 2-oxindole/1-teralone exclusively forms the C3-alkylated product. Whereas, allowing this reaction mixture to occur under an air atmosphere predominantly forms C3-alkylated 3-hydroxyindolin-2-one via domino C–H alkylation and aerobic C–H hydroxylation. This Ru-NHC catalyst is easily accessible, air stable, and phosphine free. Using this method, synthesis of 2-oxindole based natural products such as Donaxaridine was accomplished.

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“…Next, we tested oxidation reactions of a key intermediate 5 based on the reports to introducing hydroxy group at α-position of oxindole (Table 1). Oxidation reactions using combination of air and t-BuOK (Chaudhari, Sutar, Malpathak, Hazra, & Gnanaprakasam, 2017), H 2 O 2 and mCPBA afforded undesired phenol 10 without introducing hydroxy groups at 3-position of compound 5 (entries 1-3). Also, the reactions using 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO; Zhu et al, 2018) or tetrabutylammonium fluoride (TBAF; Buckley & Beatriz Fernández, 2013) resulted in no reaction (entries 4 and 5).…”

Section: Chemistrymentioning

confidence: 99%

Design, synthesis and evaluations of spiro‐fused benzoxaborin derivatives as novel boron‐containing compounds

et al. 2019

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Drug design using boron‐containing heterocycles has attracted a great deal of attention because these compounds are believed to possess high biological activity. However, information on the synthetic methodology and pharmacokinetic profiling of boron‐containing compounds is limited. In this study, we provide a new synthetic route for preparation of spiro‐fused benzoxaborin derivatives and investigate their in vitro pharmacokinetic properties. Our efforts led to the successful construction of a chemical library of spiro‐fused benzoxaborin derivatives with appropriate physicochemical and in vitro pharmacokinetic properties for oral drugs. These results indicate that the synthesized boron‐containing compounds are therefore eligible for classification in a novel chemical library.

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Transition-Metal-Free C–H Hydroxylation of Carbonyl Compounds

Cited by 74 publications

References 45 publications

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene Enhances Activity of Peroxide Intermediates in Phosphine‐Free α‐Hydroxylation of Ketones

1,5,7‐Triazabicyclo[4.4.0]dec‐5‐ene Enhances Activity of Peroxide Intermediates in Phosphine‐Free α‐Hydroxylation of Ketones

Ru-NHC Catalyzed Domino Reaction of Carbonyl Compounds and Alcohols: A Short Synthesis of Donaxaridine

Design, synthesis and evaluations of spiro‐fused benzoxaborin derivatives as novel boron‐containing compounds

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