Synthesis of P2C2O2 and P2CO via NHC-mediated coupling of the phosphaethynolate anion

Gilliard, Robert J.; Suter, Riccardo; Schrader, Erik; Benkő, Zoltán; Rheingold, Arnold L.; Protasiewicz, John D.

doi:10.1039/c7cc07654a

Cited by 20 publications

(12 citation statements)

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“…[52] Another interesting case of double decarbonylation was observed when ac hloroimidazolium chloride was reacted with two equivalents of Na(OCP), as pictured in Scheme 12. [53] When this reaction is performed at low temperature,r ed crystals can be isolated that consist of aNheterocyclic carbene (NHC)-substituted 1,3,4-oxodiphosphole.W hent his compound is heated between 55-60 8 8Ci n benzene in the presence of free NHC,aq uantitative decarbonylation occurs to give the acyclicN HC À CO À P 2 À NHC compound as green crystals.S ubsequent heating of this compound above 60 8 8Ca llows for the loss of the second equivalent CO to give the NHC stabilized P 2 molecule although in low yield. NHC!P 2 !…”

Section: Reviewsmentioning

confidence: 99%

The Chemistry of the 2‐Phosphaethynolate Anion

2018

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In all likelihood the first synthesis of the phosphaethynolate anion, PCO , was performed in 1894 when NaPH was reacted with CO in an attempt to make Na(CP) accompanied by elimination of water. This reaction was repeated 117 years later when it was discovered that Na(OCP) and H are the products of this remarkable transformation. Li(OCP) was synthesized and fully characterized in 1992 but this salt proved to be too unstable to allow for a detailed investigation of its chemistry. It was not until the heavier analogues of this lithium salt were isolated, Na(OCP) and K(OCP) (both of which are remarkably stable and can be even dissolved in water), that the chemistry of this new functional group could be explored. Here we review the chemistry of the 2-phosphaethynolate anion, a heavier phosphorus-containing analogue of the cyanate anion, and describe the wide breadth of chemical transformations for which it has been thus far employed. Its use as a ligand, in decarbonylative and deoxygenative processes, and as a building block for novel heterocycles is described. In the mere twenty-six years since Becker first reported the isolation of this remarkable anion, it has become a fascinating reagent for the synthesis of a vast library of, often unprecedented, molecules and compounds.

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Section: Reviewsmentioning

confidence: 99%

The Chemistry of the 2‐Phosphaethynolate Anion

2018

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“…When two equivalents of 2b were added to a slurry of 101b in THF at –78 °C, red solid 110 was generated as sole P‐containing product in 34 % yield. The 31 P NMR spectrum signaled two doublets at δ = 299.0 and 74.6 ppm with a coupling constant 1 J PP = 484 Hz …”

Section: Reactivity Of 2‐phosphaethynolatesmentioning

confidence: 99%

“…Although the mechanism of this transformation is not completely elucidated, an initial redox reaction between the components to give NHC 96 and (PCO) 2 is obvious. NHC attack on a ring phosphorus atom of 110 and loss of CO may be responsible for the genesis of the by‐product 111 …”

Section: Reactivity Of 2‐phosphaethynolatesmentioning

confidence: 99%

2‐Phospha‐ and 2‐Arsaethynolates – Versatile Building Blocks in Modern Synthetic Chemistry

Weber

2018

Eur J Inorg Chem

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2-Phosphaethynolates, particularly the sodium salts, Na(OCP), are exceedingly versatile nucleophiles, which renders these species important as precursors to phosphorus-containing π-conjugated heterocycles. Moreover, the 2-phosphaethynolate anion serves as a potent phosphide transfer reagent giving rise to the first stable phosphinidine among other prod-[a] Centrum für Molekulare Materialien, 2176 Scheme 3. Synthesis of [Na(dme) 2 (PCO)] 2 (2a) from 3by bond metathesis.philicity of carbon monoxide is considerably increased by ligation to the iron center, and where 2b was observed as the only P-containing product. [7] In keeping with this, heating a DMF solution of K 3 P 7 and [18]-crown-6 to 150°C under an atmosphere of CO led to the formation of [K([18]-crown-6)](PCO) 5 in addition to polyphosphides K 2 P 16 and K 3 P 21 . Aqueous work up allowed the isolation of 5 as a colorless solid in 38 % yield (Scheme 4). [9] Scheme 4. Synthesis of 5. Alkali Earth Metal 2-PhosphaethynolatesAttempts to emulate Becker's protocol for [Li(dme) 2 ](PCO) with alkaline earth metals was largely met with failure. Exposure of M[P(SiMe 3 ) 2 ] 2 to dimethyl carbonate in THF or DME afforded the corresponding magnesium (6), calcium (7), strontium (8) and barium (9) bis(2-phosphaethynolates), which slowly decomposed in the ethereal solvent. Rapid deterioration of the products was observed in hydrocarbon solvents or by removal of coordinating solvent molecules in vacuo.Solely in the case of the calcium derivative 7, where three DME ligands obviously imparted sufficient stability to the crystals full structural characterization was possible. Otherwise, identification of compounds 6-9 was restricted to NMR evidence (Scheme 5). [6d] Notably, combination of Sr[P(SiMe 3 ) 2 ] 2 with an excess of dimethyl carbonate yielded a few crystals of dinuclear 10, as confirmed by X-ray techniques. [6d] Eur. 2187 Scheme 32. Alkylation reactions of dianion 55 with 2-iodopropane and 4,4′,4′′-trimethoxyphenylmethyl chloride. Scheme 33. Preparation of Li(PCS) (58). 2193 Scheme 49. Synthesis of 98 from 99 and P(SiMe 3 ) 3 . Scheme 50. Synthesis of 98 from Na(OCP) or P 7 (SiMe 3 ) 3 . Scheme 51. Proposed mechanism for the formation of phosphaalkene 98′ from 101′ and (PCO) -(R = Me). Scheme 73. Synthesis of 145 {[K] + = [K{18}-crown-6] + }. 2201 Scheme 79. Synthesis of 153a and 154a. Scheme 80. Synthesis of 153b. Scheme 81. Preparation of 155 and 156 by deprotonation of 152c. Eur. J. Inorg. Chem. 2018, 2175-2227 www.eurjic.org Scheme 95. Formation of adducts 192a-e. Scheme 96. Reaction of 168 with N-heterocyclic carbenes 96 and 193b,c.

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“…[52] Ein weiteres interessantes Beispiel fürd ie zweifache Decarbonylierung wurde bei der Umsetzung von Chlorimidazoliumchlorid mit zwei ¾quivalenten Na(OCP) entdeckt (Schema 12). [53] Bei niedriger Temperatur liefert diese Reaktion isolierbare rote Kristalle eines NHC-substituierten 1,3,4-Oxodiphosphols.E rhitzen dieser Verbindung auf 55-60 8 8Ci nB enzol in Gegenwart von freiem NHC führt zu quantitativer Decarbonylierung,w obei die acyclische Verbindung NHC-CO-P 2 -NHC in Form grüner Kristalle entsteht. Durch anschließendes Erhitzen dieser Verbindung auf Schema 9.…”

Section: Methodsunclassified

“…Ein weiteres interessantes Beispiel für die zweifache Decarbonylierung wurde bei der Umsetzung von Chlorimidazoliumchlorid mit zwei Äquivalenten Na(OCP) entdeckt (Schema ) . Bei niedriger Temperatur liefert diese Reaktion isolierbare rote Kristalle eines NHC‐substituierten 1,3,4‐Oxodiphosphols.…”

Section: Decarbonylierungs‐ Und Desoxygenierungsreaktionenunclassified

Die Chemie des 2‐Phosphaethinolat‐Anions

Goicoechea

Grützmacher²

2018

Angewandte Chemie

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Die erste Synthese des 2‐Phosphaethinolat‐Anions, PCO−, gelang sehr wahrscheinlich bereits 1894 bei dem Versuch, durch Umsetzung von NaPH2 mit Kohlenmonoxid Na(CP) herzustellen. Erst 117 Jahre später wurde diese Reaktion wiederholt und entdeckt, dass Na(OCP) und H2 die Produkte dieser Umsetzung sind. Li(OCP) wurde 1992 synthetisiert und vollständig charakterisiert, jedoch erwies sich dieses Salz als zu instabil, um detaillierte Untersuchungen vornehmen zu können. Man benötigt die schwereren Analoga dieses Lithiumsalzes, Na(OCP) und K(OCP), die beachtlich stabil sind und sogar in Wasser gelöst werden können, um die Chemie dieser neuen funktionellen Gruppe vollständig zu erforschen. Wir geben hier einen Überblick über die Chemie des 2‐Phosphaethinolat‐Anions, eines schweren Phosphoranalogons des Cyanat‐Anions, und beschreiben das breite Spektrum an chemischen Transformationen, in denen es bisher eingesetzt wurde. Seine Verwendung als Ligand, als Reagenz in Decarbonylierung‐ und Deoxygenierungsprozessen sowie als Baustein für neuartige Heterocyclen wird berichtet. In den 26 Jahren seit Becker über die Isolierung dieses bemerkenswerten Anions erstmals berichtete, ist es zu einem faszinierenden Reagens für die Synthese einer Vielzahl von – oftmals beispiellosen – Molekülen und Verbindungen geworden.

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Synthesis of P₂C₂O₂ and P₂CO via NHC-mediated coupling of the phosphaethynolate anion

Abstract: The reaction of the chloroimidazolium chloride salt, [NHC-Cl][Cl], NHC = C{N(2,6-iPr2C6H3)CH}2 (1) with two equivalents of sodium phosphaethynolate, Na[OCP]·(dioxane)2.5, results in the formation of NHC-{cyclo-(CO)-P2-C(O)} (2) and NHC-P2-C(O)-NHC (3).

Cited by 20 publications

References 31 publications

The Chemistry of the 2‐Phosphaethynolate Anion

The Chemistry of the 2‐Phosphaethynolate Anion

2‐Phospha‐ and 2‐Arsaethynolates – Versatile Building Blocks in Modern Synthetic Chemistry

Die Chemie des 2‐Phosphaethinolat‐Anions

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