Carbon-phosphorus Bond Cleavage Research Articles

Nickel-catalyzed direct methylation of arylphosphines via carbon-phosphorus bond cleavage using AlMe3.

We report herein on the nickel-catalyzed methylation of arylphosphines using AlMe3via the cleavage of unactivated C(aryl)-P bonds. This reaction allows for the direct, catalytic substitution of an aryl group on a phosphorus center with a methyl group. This catalytic methylation can proceed, when phosphine oxides and sulfides are used as a substrate.

Selective carbon-phosphorus bond cleavage: expanding the toolbox for accessing bulky divalent lanthanoid sandwich complexes.

The synthesis of two new tetra- and penta-phenycyclopentadienyldiphenylphosphine pro-ligands which readily undergo selective C-P bond cleavage has allowed for the facile synthesis of bulky divalent octa- and deca-phenylmetallocenes of europium, ytterbium and samarium.

ChemInform Abstract: Palladium‐Catalyzed Synthesis of Six‐Membered Benzofuzed Phosphacycles via Carbon—Phosphorus Bond Cleavage.

AbstractThe first catalytic method for the synthesis of P,X‐bridged biaryl derivatives is developed.

Palladium-catalyzed synthesis of six-membered benzofuzed phosphacycles via carbon-phosphorus bond cleavage.

The palladium-catalyzed synthesis of dibenzofused six-membered phosphacycles via carbon-phosphorus bond cleavage is developed. This method is compatible with a range of functional groups, such as esters, amides, and carbamates, which is in sharp contrast to the limitations of the classical method using organolithium reagents.

Utilization of Glyphosate as Phosphate Source: Biochemistry and Genetics of Bacterial Carbon-Phosphorus Lyase

After several decades of use of glyphosate, the active ingredient in weed killers such as Roundup, in fields, forests, and gardens, the biochemical pathway of transformation of glyphosate phosphorus to a useful phosphorus source for microorganisms has been disclosed. Glyphosate is a member of a large group of chemicals, phosphonic acids or phosphonates, which are characterized by a carbon-phosphorus bond. This is in contrast to the general phosphorus compounds utilized and metabolized by microorganisms. Here phosphorus is found as phosphoric acid or phosphate ion, phosphoric acid esters, or phosphoric acid anhydrides. The latter compounds contain phosphorus that is bound only to oxygen. Hydrolytic, oxidative, and radical-based mechanisms for carbon-phosphorus bond cleavage have been described. This review deals with the radical-based mechanism employed by the carbon-phosphorus lyase of the carbon-phosphorus lyase pathway, which involves reactions for activation of phosphonate, carbon-phosphorus bond cleavage, and further chemical transformation before a useful phosphate ion is generated in a series of seven or eight enzyme-catalyzed reactions. The phn genes, encoding the enzymes for this pathway, are widespread among bacterial species. The processes are described with emphasis on glyphosate as a substrate. Additionally, the catabolism of glyphosate is intimately connected with that of aminomethylphosphonate, which is also treated in this review. Results of physiological and genetic analyses are combined with those of bioinformatics analyses.

Cover Picture: Palladium-Catalyzed Direct Synthesis of Phosphole Derivatives from Triarylphosphines through Cleavage of Carbon-Hydrogen and Carbon-Phosphorus Bonds (Angew. Chem. Int. Ed. 45/2013)

A catalytic method to synthesize a diverse array of phosphorus-bridged biaryls from readily available tertiary phosphines is described by K. Baba, M. Tobisu, and N. Chatani in their Communication on page 11892 ff. The substrate must surmount two barriers, namely the cleavage of CH and CP bonds, to be transformed into the product. This process is facilitated by a palladium catalyst to afford various phosphorus-based π systems, some of which exhibit intense solid-state fluorescence.

A comparative study of the reactivity of the lightly stabilized cluster [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] towards tri(2-thienyl)-, tri(2-furyl)- and triphenyl-phosphine

Reactions of the lightly stabilized triosmium cluster [Os3(CO)8{μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] with tri(2-thienyl)phosphine (PTh3) and tri(2-furyl)phosphine (PFu3) are described and compared to analogous reactions with PPh3. At room temperature, a number of products are isolated: [Os3(CO)10(μ-dppm)] from CO addition, [Os3(CO)8(PR3){μ3-Ph2PCH2P(Ph)C6H4}(μ-H)] from phosphine addition, [Os3(CO)9(PR3)(μ-dppm)] from phosphine and CO addition and [Os3(CO)8(PR3)2(μ-dppm)] from addition of two equivalents of phosphine. The latter are shown by NMR and X-ray diffraction to exist as 1,2-isomers, whereby one phosphine is bound to the non-dppm-substituted center and the second shares an osmium atom with one end of the diphosphine. Heating 1,2-[Os3(CO)8(PTh3)2(μ-dppm)] at 100 °C results in its clean isomerization to the 1,1-isomer in which both monodentate phosphines are located on the same osmium atom. Prolonged heating of [Os3(CO)8(PR3)2(μ-dppm)] (R = Th, Ph) at 110 °C gives [Os3(CO)9(PR3)(μ-dppm)] and the new lightly stabilized clusters [Os3(CO)7(PR3){μ3-Ph2PCH2P(Ph)C6H4}(μ-H)], the latter being formed by loss of phosphine and CO with concurrent metalation of a phenyl ring. Heating [Os3(CO)8(PFu3)2(μ-dppm)] at 110 °C gives [Os3(CO)9(PFu3)(μ-dppm)] together with the carbon-phosphorus bond cleavage products [Os3(CO)7(μ-PFu2)(μ3-η2-C4H2O)(μ-H)(μ-dppm)] and [Os3(CO)7(μ-PFu2)(μ3-η2-C6H3CH3)(μ-H)(μ-dppm)]. All new compounds were characterized by analytical and spectroscopic techniques together with single crystal X-ray diffraction analysis of nine clusters. Density functional theory (DFT) calculations have been carried out on isomers of [Os3(CO)8(PR3)2(μ-dppm)] in order to understand the observed isomer ratios.

ChemInform Abstract: Pd(II)‐Catalyzed Oxidative Heck‐Type Reaction of Triarylphosphines with Alkenes via Carbon—Phosphorus Bond Cleavage.

Abstract A Pd(II)-catalyzed oxidative Heck-type reaction of triarylphosphines with alkenes via carbon–phosphorus bond cleavage was reported. Under the optimal reaction conditions, most reactions proceeded smoothly to give the expected coupling products in acceptable to high yields.

Reaction of HppE with Substrate Analogues: Evidence for Carbon–Phosphorus Bond Cleavage by a Carbocation Rearrangement

(S)-2-hydroxypropylphosphonic acid ((S)-2-HPP) epoxidase (HppE) is an unusual mononuclear non-heme iron enzyme that catalyzes the oxidative epoxidation of (S)-2-HPP in the biosynthesis of the antibiotic fosfomycin. Recently, HppE has been shown to accept (R)-1-hydroxypropylphosphonic acid as a substrate and convert it to an aldehyde product in a reaction involving a biologically unprecedented 1,2-phosphono migration. In this study, a series of substrate analogues were designed, synthesized, and used as mechanistic probes to study this novel enzymatic transformation. The resulting data, together with insights obtained from density functional theory calculations, are consistent with a mechanism of HppE-catalyzed phosphono group migration that involves the formation of a carbocation intermediate. As such, this reaction represents a new paradigm for biological C-P bond cleavage.

Pd(II)-catalyzed oxidative Heck-type reaction of triarylphosphines with alkenes via carbon–phosphorus bond cleavage

A Pd(II)-catalyzed oxidative Heck-type reaction of triarylphosphines with alkenes via carbon–phosphorus bond cleavage was reported. Under the optimal reaction conditions, most reactions proceeded smoothly to give the expected coupling products in acceptable to high yields.

Generation of σ,π-furyl and thienyl ligands at di-iron centers via facile phosphorus–carbon bond cleavage: Synthesis and molecular structures of [Fe2(CO)6(μ-η1,η2-C4H3E){μ-P(C4H3E)2}] (E = O, S)

Treatment of [Fe3(CO)12] with tri(2-furyl)phosphine (PFu3) or tri(2-thienyl)phosphine (PTh3) in dichloromethane at 40°C leads to facile phosphorus–carbon bond scission affording di-iron furyl- and thienyl-bridged complexes [Fe2(CO)6(μ-η1,η2-C4H3E){μ-P(C4H3E)2}] (1E=O, Fu; 3E=S, Th) in good yields, together with smaller amounts of the phosphine-substituted [Fe2(CO)5(μ-η1,η2-C4H3E){μ-P(C4H3E)2}{P(C4H3E)3}] (2E=O, 4E=S). When the same reactions were carried out at room temperature, small amounts of the tri-iron clusters [Fe3(CO)11{P(C4H3E)3}] (5E=O, 6E=S) were isolated in which the coordinated phosphine(s) remain intact. Thermolysis of [Fe3(CO)11{P(C4H3E)3}] at 40°C in dichloromethane gave [Fe2(CO)6(μ-η1,η2-C4H3E){μ-P(C4H3E)2}], which also undergo phosphine substitution under similar conditions. However, both of these processes are too slow to account for the reaction product ratios and yields observed in the room temperature reactions. In contrast, addition of catalytic amounts of Na+[Ph2CO] to 5 resulted in the rapid formation of 1. We therefore propose that these reactions may occur via a radical-initiated mechanism proceeding through the initial formation of the 49-electron radical anions [Fe3(CO)11{P(C4H3E)3}]. The crystal structures of [Fe2(CO)6(μ-η1,η2-Fu)(μ-PFu2)] (1), [Fe2(CO)5(μ-η1,η2-Fu)(μ-PFu2)(PFu3)] (2), [Fe2(CO)6(μ-η1,η2-Th)(μ-PTh2)] (3) and [Fe3(CO)11(PFu3)] (5) have been determined. The di-iron complexes all show the expected cis arrangement of three-electron donor ligands, short iron–iron distances consistent with a 34-valence electron count, and, in 2, the phosphine is coordinated to the π-bound iron atom and lies trans to the metal–metal bond. Close inspection of the bonding parameters within the Fe2C2E core reveals that these alkenyl species are quite different to those without electron-withdrawing substituents. The tri-iron cluster 5 has two independent molecules in the asymmetric unit. Each contains two bridging carbonyls and the molecules differ in the relative positions of these carbonyls and the coordinated phosphine ligand, the latter lying in the equatorial plane in both molecules.

Backbone Modified Small Bite-Angle Diphosphines: Synthesis, Structure and Regioselective Thermal Rearrangements of Os3(CO)10{μ-Ph2PCH(Me)PPh2}

Addition of 1,1-bis(diphenylphosphino)ethane, Ph2PCH(Me)PPh2, to Os3(CO)12 in benzene at 60 °C in the presence of Me3NO affords Os3(CO)10{μ-Ph2PCH(Me)PPh2} (1) in almost quantitative yield. Thermolysis of 1 in boiling toluene gives the expected electronically-unsaturated 46-electron triosmium cluster Os3(CO)8{μ3-Ph2PCH(Me)P(Ph)C6H4}(μ-H) (2) as the major product formed from the regioselective activation of a phenyl ring lying anti to the methyl group in 1. A second minor product is Os3(CO)8{μ3-Ph2PC(Me)P(Ph)C6H4}(μ-H)2 (3) resulting from the activation of methine and phenyl protons. This complex contains an unusual semi-bridging tertiary phosphine ligand characterized by short [2.398(1) A] and long [2.872(1) A] osmium–phosphorus interactions which structurally resembles an intermediate during phosphine migration across a metal–metal edge. The extent of the bonding in this potential three-center, two-electron interaction was examined by electronic structure calculations. The Wiberg bond index for the short Os(1)–P(1) bond is as expected but the long Os(3)–P(1) interaction is nearly an order of magnitude smaller, which suggests that there is no significant interaction between the Os(3) and P(1) centers. Prolonged heating of 2 in boiling toluene leads to the formation of Os3(CO)7(η6-C6H5CH3){μ3-PhPCH(Me)P(Ph)C6H4} (4), while in octane Os3(CO)9{μ3-PhPCH(Me)P(Ph)C6H4} (5) is generated. Both contain the 6-electron μ3-PhPCH(Me)P(Ph)C6H4 ligand formed as a result of carbon–phosphorus bond cleavage, while in 4 toluene has displaced three carbonyls. The molecular structures of 1–4 have been determined by single crystal X-ray diffraction analysis.

Synthesis and reactivity of substituted α-carbonylphosphonites and their derivatives

Convenient methods for the synthesis of functionalized organophosphorus compounds containing carbonyl groups as well as di- or trialkoxymethyl fragments attached to phosphorus, and their derivatives, starting from the available derivatives of trivalent phosphorus acids, are proposed, and some properties of the new functionalized organophosphorus compounds are presented. So, the alkylation and acylation reaction of (dialkoxymethyl) phosphonites and their analogs have been studied. It is found that the Arbuzov rearrangement of these compounds was accompanied by the phosphorus–carbon bond cleavage with unique retention of the three-coordinate phosphorus. © 2012 Wiley Periodicals, Inc. Heteroatom Chem 23:352–372, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/hc.21024

Reactivity of tri(2-furyl)phosphine (PFu3) with [Mn2(CO)10–n(NCMe)n] (n = 0–2): X-ray Structure of mer-[Mn(CO)3(η1-C4H3O)(PFu3)2

Reaction of tri(2-furyl)phosphine (PFu3) with [Mn2(CO)10−n(NCMe)n] (n=1, 2) at room temperature furnished the substituted complexes [Mn2(CO)10−n(PFu3)n] (1–2). Direct reaction between Mn2(CO)10 and PFu3 in refluxing toluene also afforded 2 together with mer-[Mn(CO)3(η1-C4H3O)(PFu3)2] (3) resulting from phosphorus–carbon bond cleavage of the phosphine. All three new complexes have been characterized by spectroscopic data together with single crystal X-ray diffraction studies for 3.

A new route to α-alkyl-α-fluoromethylenebisphosphonates

A new route to α-alkyl-α-fluoromethylenebisphosphonates, 2 has been developed starting from commercially available tetraethyl fluoromethylenebisphosphonate (1), and alkyl halides using either caesium carbonate in DMF or sodium dimsyl. De-esterification of 2 provided biologically important α-alkyl-α-fluoromethylenebisphosphonic acid, 3, while alkoxide-induced carbon-phosphorus bond cleavage of 2 gave α-fluorophosphonates, 4, which are useful synthons in organic synthesis.

Reactivity of phenyldi(2-thienyl)phosphine towards group 7 metal carbonyls: Carbon–phosphorus bond activation

Addition of phenyldi(2-thienyl)phosphine (PPhTh 2) to [Re 2(CO) 10− n (NCMe) n ] ( n = 1, 2) affords the substitution products [Re 2(CO) 10− n (PhPTh 2) n ] ( 1, 2) together with small amounts of fac-[ClRe(CO) 3(PPhTh 2) 2] ( 3) ( n = 2). Reaction of [Re 2(CO) 10] with PPhTh 2 in refluxing xylene affords a mixture which includes 2, [Re 2(CO) 7(PPhTh 2)(μ-PPhTh)(μ-H)] ( 4), [Re 2(CO) 7(PPhTh 2)( μ-PPhTh)(μ-η 1,κ 1(S)-C 4H 3S)] ( 5) and mer-[HRe(CO) 3(PPhTh 2) 2] ( 6). Phosphido-bridged 4 and 5 are formed by the carbon–phosphorus bond cleavage of the coordinated PPhTh 2 ligand, the cleaved thienyl group being retained in the latter. Reaction of [Mn 2(CO) 10] with PPhTh 2 in refluxing toluene affords [Mn 2(CO) 9(PPhTh 2)] ( 7) and the carbon–phosphorus bond cleavage products [Mn 2(CO) 6(μ-PPhTh)(μ-η 1,η 5-C 4H 3S)] ( 8) and [Mn 2(CO) 5(PPhTh 2)(μ-PPhTh)(μ-η 1,η 5-C 4H 3S)] ( 9). Both 8 and 9 contain a bridging thienyl ligand which is bonded to one manganese atom in a η 5-fashion.

Reactivity of the triruthenium ortho-metalated cluster [Ru 3(CO) 9{μ 3-η 1,κ 1,κ 2-PhP(C 6H 4)CH 2PPh}] with tri(2-thienyl)phosphine and tri(2-furyl)phosphine: Formation of 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine complexes via phosphorus–carbon bond formation

Reaction of [Ru 3(CO) 9{μ 3-η 1,κ 1,κ 2-PhP(C 6H 4)CH 2PPh}] ( 1) with tri(2-thienyl)phosphine (PTh 3) in refluxing THF afforded [Ru 3(CO) 9(PTh 3)(μ-dpbm)] ( 3) {dpbm = PhP(C 6H 4)(CH 2)PPh} and [Ru 3(CO) 6(μ-CO) 2{μ-κ 1,η 1-PTh 2(C 4H 2S)}{μ 3-κ 1,κ 2-Ph 2PCH 2PPh}] ( 5) in 18% and 12% yields, respectively, while a similar reaction with tri(2-furyl)phosphine (PFu 3) gave [Ru 3(CO) 9(PFu 3)(μ-dpbm)] ( 4) and [Ru 3(CO) 7(μ-η 1,η 2-C 4H 3O)(μ-PFu 2){μ 3-η 1,κ 1,κ 2-PhP(C 6H 4)CH 2PPh}] ( 6) in 24% and 27% yields, respectively. Compounds 2 and 4 are phosphine adducts of 1 in which the diphosphine ligand is transformed into 1,3-diphenyl-2,3-dihydro-1H-1,3-benzodiphosphine (dpbm) via phosphorus–carbon bond formation. Cluster 5 results from metalation of a thienyl ring, the cleaved proton being transferred to the diphosphine. Carbon–phosphorus bond cleavage of a PFu 3 ligand is observed in 6 to afford a phosphido-bridge and a furyl fragment, the latter bridging in a σ,π-vinyl fashion. The molecular structures of 3, 5 and 6 have been determined by X-ray diffraction studies.

Activation of tri(2-furyl)phosphine at a dirhenium centre: Formation of phosphido-bridged dirhenium complexes

Reaction of tri(2-furyl)phosphine (PFu 3) with [Re 2(CO) 10− n (NCMe) n ] ( n = 1, 2) at 40 °C gave the substituted complexes [Re 2(CO) 10− n (PFu 3) n ] ( 1 and 2), the phosphines occupying axial position in all cases. Heating [Re 2(CO) 10] and PFu 3 in refluxing xylene also gives 1 and 2 together with four phosphido-bridged complexes; [Re 2(CO) 8− n (PFu 3) n (μ-PFu 2)(μ-H)] ( n = 0, 1, 2) ( 3– 5) and [Re 2(CO) 6(PFu 3) 2(μ-PFu 2)(μ-Cl)] ( 6) resulting from phosphorus–carbon bond cleavage. A series of separate thermolysis experiments has allowed a detailed reaction pathway to be unambiguously established. A similar reaction between [Re 2(CO) 10] and PFu 3 in refluxing chlorobenzene furnishes four complexes which include 1, 2, 6 and the new binuclear complex [Re 2(CO) 6(η 1-C 4H 3O) 2(μ-PFu 2) 2] ( 7). All new complexes have been characterized by a combination of spectroscopic data and single crystal X-ray diffraction studies.

Carbon−Phosphorus Bond Activation of Tri(2-thienyl)phosphine at Dirhenium and Dimanganese Centers

Reaction of [Re-2(CO)(9)(NCMe)] with tri(2-thienyl)phosphine (PTh3) in refluxing cyclohexane affords three substituted dirhenium complexes: [Re-2(CO)(9)(PTh3)] (1), [Re-2(CO)(8)(NCMe)(PTh3)] (2), and [Re-2(CO)(8)(PTh3)(2)] (3). Complex 2 was also obtained from the room-temperature reaction of [Re-2(CO)(8)(NCMe)(2)] with PTh3 and is an unusual example in which the acetonitrile and phosphine ligands are coordinated to the same rhenium atom. Thermolysis of 1 and 3 in refluxing xylene affords [Re-2(CO)(8)(mu-PTh2)(mu-eta(1):kappa(1)-C4H3S)] (4) and [Re-2(CO)(7)(PTh3)(mu-PTh2)(mu-H)] (5), respectively, both resulting from carbon-phosphorus bond cleavage of a coordinated PTh3 ligand. Reaction of [Re-2(CO)10] and PTh3 in refluxing xylene gives a complex mixture of products. These products include 3-5, two further binuclear products, [Re-2(CO)(7)(PTh3)(mu-PTh2)(mu-eta(1):kappa(1)-C4H3S)] (6) and [Re-2(CO)(7)(mu-kappa(1):kappa(2)-Th2PC4H2SPTh)(mu-eta(1):kappa(1)-C4H3S )] (7), and the mononuclear hydrides [ReH(CO)(4)(PTh3)] (8) and trans-[ReH(CO)(3)(PTh3)(2)] (9). Binuclear 6 is structurally similar to 4 and can be obtained from reaction of the latter with 1 equiv of PTh3. Formation of 7 involves a series of rearrangements resulting in the formation of a unique new diphosphine ligand, Th2PC4H2SPTh. Reaction of [Mn-2(CO)(10)] with PTh3 in refluxing toluene affords the phosphine-substituted product [Mn-2(CO)(9)(PTh3)] (10) and two carbon-phosphorus bond cleavage products, [Mn-2)(CO)(6)(mu-PTh2)(mu-eta(1):eta(5)-C4H3S)] (11) and [Mn-2(CO)(5)(PTh3)(mu-PTh2)(mu-PTh2)(mu-eta(1):eta(5)-C4H3S)] (12). Both 11 and 12 contain a bridging thienyl ligand that is bonded to one manganese atom in a eta(5)-fashion. The molecular structures of eight of these new complexes were established by single-crystal X-ray diffraction studies, allowing a detailed analysis of the disposition of the coordinated ligands.

Expression of the phosphonoalanine-degradative gene cluster fromVariovoraxsp. Pal2 is induced by growth on phosphonoalanine and phosphonopyruvate

The phosphonopyruvate hydrolase (PalA) found in Variovorax sp., Pal2, is a novel carbon-phosphorus bond cleavage enzyme, which is expressed even in the presence of high levels of phosphate, thus permitting phosphonopyruvate to be used as the sole carbon and energy source. Analysis of the regions adjacent to the palA gene revealed the presence of the five structural genes that constitute the 2-amino-3-phosphonopropionic acid (phosphonoalanine)-degradative operon. Reverse transcriptase-PCR (RT-PCR) experiments demonstrated that all five genes in the operon are transcribed as a single mRNA and that their transcription is induced by phosphonoalanine or phosphonopyruvate. Transcriptional fusions of the regulatory region of the phosphonoalanine degradative operon with the gfp gene were constructed. Expression analysis indicated that the presence of a LysR-type regulator (encoded by the palR gene) is essential for the transcription of the structural genes of the operon. Similar gene clusters were found in the sequenced genomes of six bacterial species from the Alpha-, Beta- and Gammaproteobacteria, and analysis of metagenomic libraries revealed that sequences related to palA are widely spread in the marine environment.