Erratum to “A mild and chemoselective method for the deprotection of tert-butyldimethylsilyl (TBDMS) ethers using iron(III) tosylate as a catalyst” [Tetrahedron Lett. 51 (2010) 1056–1058]

Bothwell, Jason M.; Angeles, Veronica V.; Carolan, James P.; Olson, Margaret E.; Mohan, Ram S.

doi:10.1016/j.tetlet.2010.05.047

Cited by 3 publications

(8 citation statements)

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“…The particles of Fe(OTs) 3 were well dispersed and no agglomeration was found on the surface of silica gel ( Fig. The particles of Fe(OTs) 3 were well dispersed and no agglomeration was found on the surface of silica gel ( Fig.…”

Section: Sem-edx Analysis Of the Fe(ots) 3 /Siomentioning

confidence: 97%

“…The reaction did not take place even after prolonged heating ( Table 2, entry 1). Using FeCl 3 , Fe(NO 3 ) 3 and Fe 2 (SO 4 ) 3 , moderate yield of product was observed ( Table 2, entries 7-9). Using FeCl 3 , Fe(NO 3 ) 3 and Fe 2 (SO 4 ) 3 , moderate yield of product was observed ( Table 2, entries 7-9).…”

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

“…When ZnCl 2 , NiCl 2 , AlCl 3 , CuCl 2 and MgCl 2 were employed as catalyst, low yield of product was obtained ( Table 2, entries 2-6). However, the use of Fe(OTs) 3 increased the efficiency, and produced high yield of product (Table 2, entry 10). However, the use of Fe(OTs) 3 increased the efficiency, and produced high yield of product (Table 2, entry 10).…”

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

“…However, the use of Fe(OTs) 3 increased the efficiency, and produced high yield of product (Table 2, entry 10). The reaction was also carried out with SiO 2 in order to evaluate role of Fe(OTs) 3 and no reaction occurred ( These results clearly indicated solvent-free condition as the best reaction condition for the model reaction using Fe(OTs) 3 /SiO 2 as catalyst. The reaction was also carried out with SiO 2 in order to evaluate role of Fe(OTs) 3 and no reaction occurred ( These results clearly indicated solvent-free condition as the best reaction condition for the model reaction using Fe(OTs) 3 /SiO 2 as catalyst.…”

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

“…First, the Fe(OTs) 3 which undergoes intramolecular cyclization to afford products 4a-k. 18 Scheme 2. First, the Fe(OTs) 3 which undergoes intramolecular cyclization to afford products 4a-k. 18 Scheme 2.…”

Section: Reaction Mechanismmentioning

confidence: 99%

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Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Tarannum

Siddiqui

2015

RSC Adv.

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A novel heterogeneous catalyst Fe(OTs) 3 /SiO 2 was synthesized and identified using FT-IR, XRD, SEM, EDX, XRF and TG analyses. The catalyst was successfully applied as a highly effective catalyst for the synthesis of a series of dibenzodiazepines under solvent-free condition. This protocol has the advantages of convenient one-pot operation, atom-economy, excellent yields in short reaction time, reusability of catalyst and environmental friendliness. 4 oxalic acid/water, acetic acid/i-propanol and sulphuric acid/ethanol which have drawbacks like use of non-recyclable catalyst, long reaction time and environmental hazards. [14][15][16][17] However, some improved methods are also reported which includes use of ZnS NPs and chitosan-Fe 3 O 4 , etc. 18,19 In this regard, exploring alternative catalysts for synthetic improvement of this reaction, we have synthesized a novel catalyst Fe(OTs) 3 /SiO 2 and analysed its catalytic potential for the synthesis of dibenzodiazepines via three-component reaction of dimedone, o-phenylenediamine and aldehydes/hetero aldehydes. The newly synthesized catalyst has been characterized with the help of FT-IR spectra, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray fluorescence (XRF) techniques. Thermal stability of the catalyst is examined by TG analysis. Results and Discussion Characterization of catalyst Fe(OTs) 3 /SiO 2 FT-IR spectrum of Fe(OTs) 3 /SiO 2The FT-IR spectrum of SiO 2 (Fig. 1a) showed a broad OH stretching absorption band in the region of 3422 cm -1 . The bands at 1110 cm -1 and 808 cm -1 were attributed to anti-symmetric and symmetric Si-O-Si stretching vibrations. Si-O-Si bending mode appeared near 473 cm -1 . For comparative analysis, the FT-IR spectrum of Fe(OTs) 3 is also included (Fig. 1b).The spectrum exhibited characteristic peaks at 3071 cm -1 and 1037 cm -1 for C-H stretching and bending vibrations. The peaks at 1262 and 1158 cm -1 were indicative of the O=S=O asymmetric and symmetric stretching vibrations, respectively. C-S stretching mode was observed at 567 cm -1 . 20

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Section: Sem-edx Analysis Of the Fe(ots) 3 /Siomentioning

confidence: 97%

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

Section: Optimization Of Reaction Conditionsmentioning

confidence: 99%

Section: Reaction Mechanismmentioning

confidence: 99%

See 3 more Smart Citations

Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Tarannum

Siddiqui

2015

RSC Adv.

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Metal‐Catalyzed Routes to Dibenzodiazepines (DBDAs) and Structural Analogues: Recent Advances

2018

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It is common knowledge that the use of transition metals as catalysts has greatly revolutionized various coupling procedures to access heterocyclic compounds of significant industrial interest. Dibenzodiazepines (DBDAs) are a particularly important group of heterocyclic compounds, with considerable pharmaceutical applications. In this review, we look at some of the catalytic methods that have been developed during the last 10 years for the synthesis of these targets. Palladium catalysts have been frequently used for these transformations, and particularly for the Buchwald–Hartwig reaction which has been a key reaction in a number of synthetic pathways. Copper has also been frequently used, including some other metals like iron and molybdenum, but to a lesser extent. In most cases, the examples chosen are for the synthesis of DBDAs with interesting medicinal properties and will be of interest to medicinal chemists. It should also be mentioned that due to the structural characteristics of these compounds the potential for diversification – principally for functional group incorporation – is immense. Emerging and facilitating technologies have also been employed for the synthesis of these molecules and are reviewed here.

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m-Terphenyl Ethers, a New Hydroxy Protecting Group Cleavable under Reductive Single Electron Transfer Reaction Conditions

Azzena¹,

Mocci²,

Pisano³

2011

Synthesis

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m-Terphenyl ethers and, to a lesser extent, 2,6-dimethoxyphenyl ethers, were tested as protected hydroxy derivatives under a variety of reaction conditions. These ethers underwent regioselective cleavage of the aromatic C(1)-O bond under reductive SET reaction conditions using alkali metals in tetrahydrofuran at room temperature. This deprotective procedure was efficiently realized in the presence of several other functional groups, including an acetal, a phenyl alkyl ether, an unprotected alcohol, and carbon-carbon double and triple bonds. Furthermore, m-terphenyl ethers proved stable under different reaction conditions, including acidic hydrolysis and formation and/or employment of different organometallic reagents.The effective protection of hydroxy groups plays a central role in many multistep reaction sequences, and there is a need to develop new and efficient protecting groups which can be selectively removed under mild reaction conditions without affecting other functionalities. 1,2 Such an efficiency can be achieved by the reduction of suitable compounds under single electron transfer (SET) reaction conditions from alkali metals or aromatic radical anions in ethereal solvents, as already demonstrated, e.g., by the reductive cleavage of allyl, 3 benzyl, 3,4 and trityl 5 ethers.Despite their well-known inertness and high reductive potential, the aromatic C-O bond of aryl alkyl ethers can be cleaved by electron transfer from alkali metals in aprotic solvents. In the course of our extensive studies on the mechanism 6,7 and synthetic usefulness 6,8 of this reaction, we reported that 2,6-dimethoxyphenyl (m-DMPh) 9 or 2,6-diphenylphenyl (m-terphenyl, m-TPh) 10 methyl ethers undergo a highly regioselective demethoxylation at the C1-position, in almost quantitative yields.To improve this procedure to develop new hydroxy protecting groups, it was necessary to investigate the reactivity towards alkali metals of several functionalized and nonfunctionalized m-TPh and m-DMPh alkyl ethers. This goal was realized, converting the appropriate phenol into the desired ethers by reacting them either with alkyl halides via the Williamson synthesis (Scheme 1) or alcohols via the ultrasound stimulated Mitsunobu reaction 11 (Scheme 2). The corresponding protected alcohols 1 and 2 were recovered in satisfactory to good yields. of ethers 1a,b, 2a,b; X = Br for 1a and 2a, or Cl for 1b and 2b; 1a, G = Ph, n = 3, R = Ph, 60%; 1b, G = Ph, n = 4, R = CH(OCH 2 ) 2 , 77%; 2a, G = OMe, n = 3, R = Ph, 70%; 2b, G = OMe, n = 4, R = CH(OCH 2 ) 2 , 85% Scheme 2 Synthesis of ethers 1c-g; 1c, n = 9, R = Me, 73%; 1d, n = 0, R = octan-2-yl, 65%; 1e, n = 2, R = pent-1-ynyl, 72%; 1f, n = 3, R = OPh, 75%; 1g, n = 6, R = Cl, 80% Scheme 1 SynthesisWe next investigated the reductive cleavage of these ethers under SET reaction conditions (Scheme 3), focusing at first our attention on the reactivity of m-TPh ethers 1a and 1b and m-DMPh ethers 2a and 2b, whose reactions with different alkali metals were investigated in some detail. Scheme 3 Reductive deprot...

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Erratum to “A mild and chemoselective method for the deprotection of tert-butyldimethylsilyl (TBDMS) ethers using iron(III) tosylate as a catalyst” [Tetrahedron Lett. 51 (2010) 1056–1058]

Cited by 3 publications

References 0 publications

Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Metal‐Catalyzed Routes to Dibenzodiazepines (DBDAs) and Structural Analogues: Recent Advances

m-Terphenyl Ethers, a New Hydroxy Protecting Group Cleavable under Reductive Single Electron Transfer Reaction Conditions

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Erratum to “A mild and chemoselective method for the deprotection of tert-butyldimethylsilyl (TBDMS) ethers using iron(III) tosylate as a catalyst” [Tetrahedron Lett. 51 (2010) 1056–1058]

Cited by 3 publications

References 0 publications

Fe(OTs)3/SiO2: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Fe(OTs)3/SiO2: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Metal‐Catalyzed Routes to Dibenzodiazepines (DBDAs) and Structural Analogues: Recent Advances

m-Terphenyl Ethers, a New Hydroxy Protecting Group Cleavable under Reductive Single Electron Transfer Reaction Conditions

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Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions

Fe(OTs)₃/SiO₂: a novel catalyst for the multicomponent synthesis of dibenzodiazepines under solvent-free conditions