�ber die umsetzung von N-fluorsulfonylisocyanat mit verschiedenen phosphorverbindungen

Hoffmann, Hartmut; Förster, Heinz; Tor-Poghossian, Grikor

doi:10.1007/bf00938269

Cited by 14 publications

(7 citation statements)

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“…On the other hand, (54) decomposes very readily into dimethyl oxalate and another methyl radical, as can be shown independently by generation of (54) from methyl dimethoxyacetate and di-tert-butyl peroxide [35]. A small quantity of (54) also dimerizes to form dimethyl tetramethoxysuccinate (16).…”

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confidence: 84%

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Reactions of Electron‐Rich Olefins

Hoffmann

1968

Angew. Chem. Int. Ed. Engl.

115

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Olefins are normally preferentially attacked by electrophiles. This trend is strengthened in enol ethers and enamines, and is particularly pronounced in tetramethoxyethylene and in tetraaminoethylenes. These electron-rich olefins are accordingly also excellent reducing agents. In their reactivity, therefore, they behave as counterparts of tetracyanoethylene. This compound shares with the electron-rich olefins a strong tendency to undergo cycloadditions, the electron-rich olefins adding particularly readily to electrophiles.

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confidence: 84%

“…[76] Several structures have been proposed for the adduct of (5) with HzO [14, 721. alkaline media leads to (35) [41, whereas acid hydrolysis results in more extensive cleavage (see Section 3.2). Only in the case of (1) has cleavage to N,N-dimsthylglyoxylamide been achieved by acid hydrolysis [501.…”

Section: Autoxidation Of Electron-rich Olefinsmentioning

confidence: 99%

Reactions of Electron‐Rich Olefins

Hoffmann

1968

Angew. Chem. Int. Ed. Engl.

115

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“…If it is assumed that primary attack of the nitromethyl-anion on C-2 or C-6 to give (2) is followed by an intramolecular aldol condensation to yield the intermediate (3). then the experimental findings may be interpreted as follows: Formation of the phenols (5) proceeds via 1.3-nitro-nitroso ester rearrangement to ( 4 ) and aromatization with subsequent hydrolysis of the phenol nitroso ester.…”

Section: Methodsmentioning

confidence: 99%

“…We attribute incomplete deuteration (75 and 21 %) in [Ddmethanol with NaBD4 and with sodium methoxide, respectively, to the isotope effect [3,41 and to water present in compound ( I ) . If the salt is prepared in D20 up to 85 % deuteraation is achieved.…”

Section: Zth@mentioning

confidence: 99%

Aryldiimine as an Intermediate during Reduction of Diazonium Salts with Tetrahydridoborate

Bloch¹,

Musso²,

Záhorszky³

1969

Angew. Chem. Int. Ed. Engl.

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Aryldiazonium salts may be reduced to the corresponding hydrocarbons by complex hydrides in methanol at 0 OC [l]. The hydrogen introduced can be transferred from various sources as anion, radical, or proton. To discriminate between these possibilities, we treated bimesityl-3,3'-bis(diazonium) bis(tetrafluorob0rate) ( I ) in methanol with sodium tetrahydridoborate; in each case the reducing agent or the solvent was deuterated in a different manner (98-99% D). The deuterium content of the resulting bimesityl, which could be isolated in approximately 22% yield by chromatography, was determined by mass spectrometry (* 1 %). 6 3 36 42 4 33 57 43 1 4.5 7 1 6 95 % D 1 2 ( 7 4 1 7 5 ( 6 4 1 3 1 2 1As is evident from Table 1, it is not the hydrido hydrogen that appears in the product but the acidic proton of the methanol to the extent of about 85 %.Since the diazonium tetrafluoroborate ( I ) is stable for two hours in methanol at room temperature, the tetrahydridoborate must first reduce the diazonium salt to the aryldiimine. The latter compound then rapidly exchanges the N-H proton with the solvent and decomposes mainly via the diimine anion to give nitrogen and an aryl anion, which abstracts a proton or deuteron from the solvent, thus yielding the hydrocarbon [2,31. ZtH@Ar-NEN"i-NaBH4Ar-N=NQIn acetonitrile, the bimolecular decomposition of phenyldiimine was formulated as a free-radical process and an isotope effect KH/KD = 4-5 was observed [41, The difference between the third and fourth columns of Table 1 shows that with hydride in methanol only about 1 5 % of aryl radicals are formed that abstract hydrogen from the C-H bond. In the reaction with 4 mol. equiv. of non-deuterated sodium methoxide the percentage of radicals increases markedly (columns 5 and 6).We attribute incomplete deuteration (75 and 21 %) in [Ddmethanol with NaBD4 and with sodium methoxide, respectively, to the isotope effect [3,41 and to water present in compound ( I ) . If the salt is prepared in D20 up to 85 % deuteraation is achieved.About 10 % of 3,3'-difluorobimesityl containing no deuterium and 8 % of 3-fluorobimesityl (also deuterated) were obtained as by-products. Decomposition of (1) in boiling methanol affords 75 % of 3,3'-difluorobimesityl and 13 % of 3-flUOr0-3'methoxybimesityl (oil), but no bimesityl. Experimental:3,3'-Diaminobimesityl(270 mg) are diazotized in 20 % hydrochloric acid (1.1 g) with NaNO2 (138 mg) in water (1 ml) a t 0 'C; the filtered solution is treated with NaBF4 (330 mg) in water (0.8 ml) and the resulting precipitate is filtered off after 30 min. The salt (350 mg), which is washed with 5 % NaBF4 solution (0.2 ml), cold methanol (0.2 ml), and ether (1 ml) successively and dried over PzO5 for 5 h under vacuum, is suspended in methanol (2 ml) and treated at 0 "C, with stirring, with NaBH4 (80mg); heat is evolved during the reaction. After 2 h the reaction mixture is extracted with n-hexane and the residue obtained after evaporation of the solvent is separated by layer chromatography on silica gel (Merck PF 254) with ligh...

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“…[1d] The example shown in Scheme 2 c, represents one of the very rare cases for which a PÀO bond is substituted by a much weaker PÀN bond. [17] A reversed Wittig reaction to form an ylide is observed when dicyanoalkyne is reacted with TPPO at elevated temperatures in benzene to exchange a PÀO bond for a PÀC bond (Scheme 2d). [18] Herein, we report a versatile and attractive concept to easily obtain value-added products from unreactive phosphane oxides.…”

Section: Introductionmentioning

confidence: 99%

A Versatile Protocol for the Quantitative and Smooth Conversion of Phosphane Oxides into Synthetically Useful Pyrazolylphosphonium Salts

Feldmann¹,

Schulz²,

Klotter³

et al. 2011

ChemSusChem

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A convenient protocol for the smooth conversion of the resistant P-O bond in phosphane oxides into a reactive P-N bond of synthetically useful pyrazolylphosphonium salts is described. A highly charged, oxophilic, phosphorus-centered trication is employed and the reactions are conducted at room temperature with quantitative yields. The resulting pyrazolylphosphonium cations are valuable synthetic intermediates and are used for the synthesis of a variety of organophosphorus compounds. This represents a new approach towards the transformation of the rather inert phosphoryl group under very mild reaction and workup conditions and aims towards alternatives to existing reduction methods for phosphane oxide functionalization.

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�ber die umsetzung von N-fluorsulfonylisocyanat mit verschiedenen phosphorverbindungen

Cited by 14 publications

References 0 publications

Reactions of Electron‐Rich Olefins

Reactions of Electron‐Rich Olefins

Aryldiimine as an Intermediate during Reduction of Diazonium Salts with Tetrahydridoborate

A Versatile Protocol for the Quantitative and Smooth Conversion of Phosphane Oxides into Synthetically Useful Pyrazolylphosphonium Salts

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