Simple and efficient preparation of sterically protected 1,4-diphosphafulvenes

Nakamura, Akitake; Toyota, Kozo; Yoshifuji, Masaaki

doi:10.1016/j.tet.2005.03.080

Cited by 14 publications

(8 citation statements)

References 26 publications

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“…Phosphaallenes 23 and 24 decompose at room temperature in solution, and these reactions seem to be catalysed by the base in accordance with observations on related systems . Compared to the syntheses in the presence of DBU, the phosphaallenes 23 and 24 obtained by alkynide elimination show a considerably longer lifetime (about a factor of two).…”

Section: Resultsmentioning

confidence: 99%

“…Decomposition of phosphaallenes afforded different products by dimerization via their P=C (head‐to‐tail) or C=C bonds . Particularly interesting was the base catalysed formation of 1,4‐diphosphafulvenes with unsaturated five‐membered P 2 C 3 ‐heterocycles by [3+2]‐cycloaddition. They had endo ‐ and exocyclic C=C bonds and were isolated as 1:1 mixtures of E / Z ‐isomers, which could not be separated by crystallization or chromatography.…”

Section: Resultsmentioning

confidence: 99%

“…Phosphaallenes 23 and 24 decompose at room temperature in solution, and these reactions seem to be catalysed by the base in accordance with observations on related systems. [28,29] Compared to the syntheses in the presence of DBU, the phosphaallenes 23 and 24 obtained by alkynide eliminations how a considerably longerl ifetime (about af actor of two). Because this route seemedn ot to be suitable to generate 24 in ap ure form or to trap it in secondary reactions, we abstained from the synthesis in ap reparative scale.…”

Section: H-phosphaallenesmentioning

confidence: 99%

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3H‐Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β‐Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms

Klöcker

Tendyck

Keweloh

et al. 2019

Chemistry A European J

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A facile method for the efficient synthesis of 3H‐phosphaallenes, R−P=C=C(H)−R′, is presented, which comprises treatment of dialkynylphosphines with dialkylaluminium hydrides (hydroalumination) and elimination of aluminium alkynides from intermediate alkenyl‐alkynylphosphines. The stability of the phosphaallenes depends on steric shielding by the substituents at phosphorus (aryl or CH(SiMe3)2 groups). Only supermesityl compounds are persistent at room temperature in solution. This simple method starting with easily accessible dialkynylphosphines and commercially available aluminium hydrides (HAlEt2, HAliBu2) allows the generation of transient species, which were trapped by coordination to transition metals. The η1‐coordination via a P−W bond was observed for tungsten, while the side‐on coordination via the P=C bond resulted with platinum. Decomposition of the mesityl derivative yielded an unprecedented product, which may be formed by 1,3‐H shift to the P atom, hydrophosphination of the P=C bond of a second phosphaallene and formation of a P−P bond.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: H-phosphaallenesmentioning

confidence: 99%

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3H‐Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β‐Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms

Klöcker

Tendyck

Keweloh

et al. 2019

Chemistry A European J

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“…Ylides generated from phosphorus-containing thiophenes are known to be highly efficient reagents for the C=C bond formation in acyclic polyenes (see products (113)(114)(115)(116)), as well as for further construction of fused heterocyclic systems based on the thiophene nucleus (see products (119,120)) [107][108][109][110][111][112].…”

Section: The Wittig Reactionmentioning

confidence: 99%

“…Isomerization of two molecules of the thienyl-substituted phosphaallene (130) provides 1,4-diphosphafulvene (131) in 52% yield [114].…”

Section: Miscellaneous Reactionsmentioning

confidence: 99%

Phosphorylation of Thiophenes

Ivonin¹,

Tolmachev²,

Пинчук³

2008

COC

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This review deals with synthetic methods, chemical transformations, and some physical properties of thienyland benzothienyl substituted phosphorus compounds bearing P-Het or P-CH 2 -Het bonds.The basic synthetic approaches to these compounds include reactions of metalated thiophenes with phosphorus(III) and (V) halides, phosphorylation of thiophenes in the presence of a mild Lewis acid, use of halogenothiophenes in the Arbuzov reaction, and phosphorylation of thiophenes with phosphorus(III) halides in basic medium. Synthetic approaches to condensed heterocyclic systems of novel types are also considered.Investigation of chemical properties of phosphorylated thiophenes has revealed that, despite the great similarity with phenyl analogues, differences connected to the nature of the heterocycle are observed. The tertiary phosphines bearing at least one thienyl substituent are less active in quaternization and oxidation reactions. At the same time, basic hydrolysis leading to C-P bond cleavage is facilitated, as compared to benzene derivatives.

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Formation and Structure of a Stable Monoradical Cation by Reduction of a Diphosphafulvenium Salt

et al. 2006

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The attention paid by physical chemists to organic radical ions has never ceased to increase over the last 20 years, [1,2] mainly because these species often act as reaction intermediates and because their structure can determine the result of many chemical processes. [3] Considerable efforts have been devoted to gaining a better knowledge of their electronic structure; unfortunately their high reactivity make their identification difficult, and reports on their crystal structures remain sparse. [4] Renewed interest in the behavior of organic ion radicals has recently appeared owing to the practical applications predicted for some of these compounds in materials science and because of their potential use as electronic devices, organic magnets, and organic conductors. [5,6] Fulvene derivatives (A, Scheme 1) play an important role in this field; for example, dithiafulvene (B) constitutes one of the elementary units of conducting, semiconducting, and superconducting molecular solids. In this context, a crucial property of tetrathiafulvalene lies in its capacity to easily release one electron to give, reversibly, a rather persistent radical cation. [7] The discovery of novel fulvene-centered systems that are able to reversibly stabilize a radical cation is of considerable interest. The results herein contribute to this project, and as will be seen further, phosphorus chemistry can open new and very attractive perspectives in this area.On the basis of early reports on the chemistry of 1,4-diphosphoniacyclohexa-2,5-dienes, [8] as well as our recent EPR study on the reduction processes of monophospholium cations C + , [9] we postulated that pentavalent phosphorus atoms could behave as strong electron acceptors and thus allow the synthesis and stabilization of persistent radical cations through reduction processes. We validate this hypothesis herein in the case of a diphosphafulvenium dication D 2+ whose reduction leads to a stable radical cation. To the best of our knowledge, diphosphafulvenium cations have never been reported so far. [10] The trans-tetraphenyldiphosphafulvene derivative 1, whose synthesis was recently reported, was chosen as the starting precursor. [11] Reaction of 1 with excess methyl triflate (MeOTf) at 25 8C cleanly afforded dication 2 2+ , which was isolated as a very stable white solid. The structure of 2 2+ was confirmed by NMR data and elemental analyses. Unfortunately, despite many attempts, 2 2+ proved to be reluctant towards crystallization, thus precluding the recording of an Xray crystal structure. As expected, dication 2 2+ can be easily reduced, as indicated by cyclic voltammetry (CH 3 CN, room temperature), which revealed four waves at À0.54 V (reversible), À1.10 V (irreversible), À1.37 (partially reversible), and À1.72 V (irreversible) versus SCE. Importantly, the first reduction process was found to be reversible even at low scan rates (50 mV s À1 ), thereby suggesting that it would be possible to isolate a persistent radical cation. Reduction of 2 2+ was Scheme 1.

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Simple and efficient preparation of sterically protected 1,4-diphosphafulvenes

Cited by 14 publications

References 26 publications

3H‐Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β‐Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms

3H‐Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β‐Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms

Phosphorylation of Thiophenes

Formation and Structure of a Stable Monoradical Cation by Reduction of a Diphosphafulvenium Salt

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