Borverbindungen, XIIQuantitative Bestimmung verschiedener B‐Funktionen in organischen Borverbindungen durch Oxydation mit Trimethylamin‐<i>N</i>‐oxid

Köster, Roland; Morita, Yoshiharu

doi:10.1002/jlac.19677040107

Cited by 127 publications

(37 citation statements)

References 14 publications

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“…44 Formation of hydrogen by reaction of B–H containing organoboranes and amine N -oxides is known. 36,37 Thus, minimally 2 mol equiv of pinB–H will be required for reducing amine oxides. In principle, trialkylboranes can be used to reduce amine N -oxides, as has been demonstrated with trimethylamine N -oxide.…”

Section: Resultsmentioning

confidence: 99%

Reduction of Amine N-Oxides by Diboron Reagents

et al. 2011

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Facile reduction of alkylamino-, anilino-, and pyridyl-N-oxides can be achieved via the use of diboron reagents, predominantly bis(pinacolato)- and in some cases bis(catecholato)diboron [(pinB)2 and (catB)2, respectively]. Reductions occur upon simply mixing the amine N-oxide and the diboron reagent in a suitable solvent, at a suitable temperature. Extremely fast reductions of alkylamino- and anilino-N-oxides occur, whereas pyridyl-N-oxides undergo slower reduction. The reaction is tolerant of a variety of functionalities such as hydroxyl, thiol, and cyano groups, as well as halogens. Notably, a sensitive nucleoside N-oxide has also been reduced efficiently. The different rates with which alkylamino- and pyridyl-N-oxides are reduced has been used to perform stepwise reduction of the N,N’-dioxide of (S)-(–)-nicotine. Because it was observed that (pinB)2 was unaffected by the water of hydration in amine oxides, the feasibility of using water as solvent was evaluated. These reactions also proceeded exceptionally well, giving high product yields. In constrast to the reactions with (pinB)2, triethylborane reduced alkylamino-N-oxides, but pyridine N-oxide did not undergo efficient reduction even at elevated temperature. Finally, the mechanism of the reductive process by (pinB)2 has been probed by 1H and 11B NMR.

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Section: Resultsmentioning

confidence: 99%

Reduction of Amine N-Oxides by Diboron Reagents

et al. 2011

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“…[18] Its remarkable functional group tolerance and quantitative nature continue to render it a mild, reliable alternative to hydrogen peroxide-mediated deborylative oxidations under challenging circumstances in total syntheses. [19] Kabalka’s subsequent recognition that the dihydrate of TMAO is just as effective as its anhydrous form [20] offered the first hint that the reaction would work in aqueous media, a necessary criterion for bioorthogonality.…”

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confidence: 99%

A Bioorthogonal Reaction of N‐Oxide and Boron Reagents

Kim

Bertozzi

2015

Angew Chem Int Ed

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Bioorthogonal reaction development has classically focused on bond-forming ligation reactions. In this report, we seek to expand the functional repertoire of such chemistries by introducing a new bond-cleaving reaction between N-oxide and boron reagents. The reaction features a large dynamic range of reactivity, showcasing second-order rate constants as high as 2.3 × 103 M−1s−1 using diboron reaction partners. Diboron displays minimal cell toxicity at millimolar concentrations, penetrates cell membranes, and effectively reduces N-oxides inside mammalian cells. This new bioorthogonal tool comprising miniscule components is well-suited for activating molecules within cells under chemical control. Additionally, we demonstrate that the metabolic diversity of nature enables the use of naturally occurring functionalities that display inherent biocompatibility alongside abiotic components for organism-specific applications.

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“…Cyclic boranes of the general formula cyclo-R-B-O-(CH 2 ) n with R¼alkyl are known for n ¼ 3; 4, and 5 [6][7][8], whereas the corresponding borates have not been reported so far. Whereas C-O-B moieties of tricoordinated boron readily hydrolyze, the bis(trifluoromethyl)borates 7-9 show no tendency to dissociation with formation of tricoordinated species and are hence stable to water and hydrolysis.…”

Section: Resultsmentioning

confidence: 99%

“…trifluoromethyl)-4-hydroxybutylborane (5), Trimethylamine-bis(trifluoromethyl)-5-hydroxypentylborane(6) To a mixture of (23.3 mmol) of H 2 C¼CH-(CH 2 ) (nÀ2) -B(CF 3 ) 2 ÁNMe 3 in 20 ml of THF 48 ml of a 0.5 m THF solution of 9-BBN (ALDRICH) were added at 20 8C and…”

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confidence: 99%