Protonation and alkylation of organophosphorus compounds with trifluoromethanesulfonic acid derivatives

Tolstikova, L. L.; Bel’skikh, A. V.; Shainyan, B. А.

doi:10.1134/s1070363211030054

Cited by 20 publications

(17 citation statements)

References 42 publications

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“…Employing trifluoromethanesulfonic acid (HOTf) instead afforded Ph 3 POH + OTf – ( 2a[OTf] ) in 97 % isolated yield as a colorless, viscous oil, which crystallized upon standing . Interestingly, 2a[OTf] features a 31 P NMR resonance at δ = 51.5 ppm (in CDCl 3 ), which is shifted downfield by 12.8 ppm compared to that of 2a[Cl] , and an OH resonance at δ 1 H 13.39 ppm that is shifted downfield by 1.07 ppm; both can be attributed to the stronger acidity of HOTf, and consequently the higher ionic character of the corresponding TPPO salt .…”

Section: Resultsmentioning

confidence: 99%

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Brønsted Acid Promoted Reduction of Tertiary Phosphine Oxides

Krachko

Lyaskovskyy

Lutz

et al. 2017

Z. Anorg. Allg. Chem.

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Recently, Brønsted acids, such as phosphoric acids, carboxylic acids, and triflic acid, were found to catalyze the reduction of phosphine oxides to the corresponding phosphines. In this study, we fully characterize the HCl, HOTf, and Me 2 SiHOTf adducts of triphenylphosphine oxide and find that the thermally stable adduct * Prof. Dr. J. C. Slootweg E-Mail: j.c.slootweg@uva.nl [a] Van' 916Ph 3 POH + OTfis efficiently converted into triphenylphosphine at 100°C in the presence of readily available hydrosiloxanes. Under the same reaction conditions, also Ph 3 POSiMe 2 H + OTfselectively affords triphenylphosphine indicating that silylated phosphine oxides are likely intermediates in this process.

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Section: Resultsmentioning

confidence: 99%

“…After stirring for 1 h at 23 °C 31 P NMR spectroscopy showed full conversion into the HOTf adduct. Afterwards, the solvent was removed under reduced pressure and the resulting oil was washed with pentane and dried, yielding 2a[OTf] as a colorless oil (97 %), which crystallized upon standing (mp. 63–67 °C).…”

Section: Methodsmentioning

confidence: 99%

Brønsted Acid Promoted Reduction of Tertiary Phosphine Oxides

Krachko

Lyaskovskyy

Lutz

et al. 2017

Z. Anorg. Allg. Chem.

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“…Under the same conditions, triphenylphosphine borane also led to A , alongside with a vigorous gas evolution which is likely to arise from a fluoride/hydride exchange followed by P−B bond cleavage . Under the same conditions, triphenylphosphine oxide led to the single cationic species B with a 31 P NMR signal at 58.97 ppm, more deshielded that analogous triflate and triflimidate salts (25.00 ppm for the neutral substrate).…”

Section: Methodsmentioning

confidence: 99%

Evidence of Phosphonium‐Carbenium Dication Formation in a Superacid: Precursor to Fluorinated Phosphine Oxides

et al. 2018

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“…To further explore this impact, the protonation of triphenylphosphine,t riphenylphosphine oxide and triphenylphosphine borane in superacid was studied by in situ low-temperature NMR spectroscopy.T riphenylphosphine was first added to the superacid HF/ SbF 5 at À20 8 8Ca nd the reaction was followed by 31 PNMR spectroscopy,r evealing the unique formation of phosphonium ion A (signal at 6.40 ppm compared to signals at 3.89 ppm and 5.28 ppm for corresponding triflate and triflimidate salts, Scheme 3). [19] Under the same conditions,t riphenylphosphine borane also led to A,a longside with av igorous gas evolution which is likely to arise from af luoride/hydride exchange followed by P À Bb ond cleavage. [20,21] Under the same conditions,triphenylphosphine oxide led to the single cationic species B with a 31 PNMR signal at 58.97 ppm, more deshielded that analogous triflate and triflimidate salts [19] (25.00 ppm for the neutral substrate).…”

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confidence: 93%

“…[19] Under the same conditions,t riphenylphosphine borane also led to A,a longside with av igorous gas evolution which is likely to arise from af luoride/hydride exchange followed by P À Bb ond cleavage. [20,21] Under the same conditions,triphenylphosphine oxide led to the single cationic species B with a 31 PNMR signal at 58.97 ppm, more deshielded that analogous triflate and triflimidate salts [19] (25.00 ppm for the neutral substrate).…”

mentioning

confidence: 93%

Evidence of Phosphonium‐Carbenium Dication Formation in a Superacid: Precursor to Fluorinated Phosphine Oxides

et al. 2018

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Unambiguously confirmed by low-temperature in situ NMR experiments,X -rayd iffraction and vibrational spectroscopy, phosphonium-carbenium superelectrophiles are shown to be generated in strong acidic conditions.R epresenting crucial intermediates,t heir exploitation allows for the synthesis of unprecedented fluorinated (cyclic) phosphine oxides.Fluorinated compounds [1] are undeniably associated with the development of catalysis, [2] agrochemicals and drugs. [3] Organophosphorus compounds have found wide application in various fields such as catalysis,medicinal chemistry,material science and inorganic chemistry. [4] To our knowledge,t he formation of fluorinated phosphines and their derivatives via direct addition is limited to af ew reactions:t he trifluoromethylfluorosulfonylation, [5] theb romodifluoromethylation [6] of allyldiphenyl phosphine oxide,the nucleophile mediated reaction of Ruppert-Prakash reagent (or perfluoroalkyltrimethylsilanes) with phosphites,o ra ddition of LiC 2 F 5 to chlorinated phosphine [7] and the unimolecular radical nucleophilic substitution reaction. [8] Although the addition of an element-hydrogen pair to an unsaturated CÀCb ond is as tandard direct strategy to functionalize am olecular skeleton, hydro-(hetero)element addition to allylic or propargylic phos-phorus containing derivatives is rather limited. [9] Thep H dependent stability and the prototropic isomerization of the corresponding phosphonium derivatives may be the reason for the difficulty to selectively add any species to these derivatives under acidic conditions. [10] To avoid undesired rearrangement, Berlin used polyphosphoric acid (115 %) at elevated temperatures to perform the intramolecular Friedel-Crafts reaction of allyltriphenyl phosphonium salts. [11] In situ formation of ad ication was postulated in this seminal contribution, whose hypothesis was recently reformulated by Va silyev and Stankevič (Scheme 1a). [12] Laali et al. [13] and Klumpp et al. [14] went astep further by,respectively,showing the protonation of tetraphosphocubane and ketophosphonium salts in superacids. [15] On this basis,w ep ostulated that the generation of as uperelectrophile from an unsaturated organophosphorus compound can be expected under superacidic conditions and further exploited to produce valuable and innovative (P,F)-derivatives.W er eport here the first example of ahydrofluorination [16] and cyclization/fluorination of unsaturated phosphine oxides.T he involvement of phosphonium-carbenium superelectrophiles (Scheme 1b)i se videnced by X-ray crystallography,l ow-temperature NMR spectroscopy and DFT calculations.This work aims to address two important challenges: 1) Thed eactivation of the unsaturation after protonation of the P-containing function, which could prevent substrates from any reaction, needs to be outweighed by the high acidity Scheme1. a) Postulated and reported phosphorus containing polycations formation in acidic conditions(literature);b)Exploitation of phosphonium-carbeniumsuperelectrophiles for the synthesis of...

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Protonation and alkylation of organophosphorus compounds with trifluoromethanesulfonic acid derivatives

Cited by 20 publications

References 42 publications

Brønsted Acid Promoted Reduction of Tertiary Phosphine Oxides

Brønsted Acid Promoted Reduction of Tertiary Phosphine Oxides

Evidence of Phosphonium‐Carbenium Dication Formation in a Superacid: Precursor to Fluorinated Phosphine Oxides

Evidence of Phosphonium‐Carbenium Dication Formation in a Superacid: Precursor to Fluorinated Phosphine Oxides

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