Phosphorus Carbon Bond Formation Research Articles

Palladium‐Catalyzed Phosphorus—Carbon Bond Formation: Cross‐Coupling Reactions of Alkyl Phosphinates with Aryl, Heteroaryl, Alkenyl, Benzylic, and Allylic Halides and Triflates.

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Palladium‐Catalyzed Phosphorus—Carbon Bond Formation: Cross‐Coupling Reactions of Alkyl Phosphinates with Aryl, Heteroaryl, Alkenyl, Benzylic, and Allylic Halides and Triflates.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Recent Advances in Phosphorus—Carbon Bond Formation: Synthesis of H‐Phosphinic Acid Derivatives from Hypophosphorous Compounds

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Palladium-catalyzed phosphorus–carbon bond formation: cross-coupling reactions of alkyl phosphinates with aryl, heteroaryl, alkenyl, benzylic, and allylic halides and triflates

The direct formation of H-arylphosphinates and related compounds can be accomplished using palladium catalysis. This full paper examines the scope and some mechanistic aspects of this phosphorus–carbon bond forming reaction. The reactions of alkenyl and allylic halides are also described for the first time. This novel cross-coupling provides a convenient access to a variety of substituted H-phosphinates.

Method for the synthesis of phosphinic acids from hypophosphites V. The synthesis of pseudo-α,α-dipeptides

The method for the synthesis of 2-substituted 2-hydroxycarbonylethyl-1-aminoalkylphosphinic acids (I) (pseudo-alpha,alpha-dipeptides) from ammonium and potassium hypophosphites (II) is described. The proposed route to the synthesis of pseudo-alpha,alpha-dipeptides consists in addition hypophosphite to acrylic compounds and formation of the first phosphorus-carbon bond with following addition of aminoacid fragment and formation of the second phosphorus-carbon bond. The key intermediates of the synthesis - phosphonous acids (III) and their silylic esters (IV) were obtained at the first stage of the process as the result of the addition of the bis(trimethylsilyl)hypophosphite in situ to suitably substituted acrylates. The modificated procedure for the Kabachnik-Fields reaction of 2-substituted 2-alkoxycarbonylethyl phosphonous acids (III), acetamide, benzaldehyde in acetic anhydride with following hydrolysis results in 2-substituted 2-hydroxycarbonylethyl-alpha-aminobenzyl phosphinic acids (Ia-c) (pseudo-phenylglycylpeptides). Bis(trimethylsilyl) 2-substituted 2-alkoxycarbonylethylphosphonites (IV) in situ were added to N-tritylmethanimine and following alcoholysis and acid hydrolysis of addition products gave 2-substituted 2-hydroxycarbonylethyl-aminomethylphosphinic acids (Id-f) (pseudo-glycylpeptides).

NiCl2-Catalyzed Hydrophosphinylation

[reaction: see text] A new nickel-based catalytic system has been developed for phosphorus-carbon bond formation. The addition of alkyl phosphinates to alkynes is catalyzed by nickel chloride in the absence of added ligand. The reaction generally proceeds in high yields, even with internal alkynes, which were poor substrates in our previously reported palladium-catalyzed hydrophosphinylation of alkyl phosphinates. The method is useful for the preparation of H-phosphinate esters and their derivatives. The one-pot synthesis of various important organophosphorus compounds is also demonstrated. The reaction can be conducted with microwave heating.

Recent advances in phosphorus–carbon bond formation: synthesis of H-phosphinic acid derivatives from hypophosphorous compounds

This account summarizes the research conducted in our laboratory over the past five years. New methodologies were devised for the formation of P–C bonds with a focus on the reactions of hypophosphorous acid derivatives. Three types of reactions have been developed: palladium-catalyzed cross-coupling, room-temperature radical addition, and palladium-catalyzed addition. Our results are summarized in each of these areas and include some of our most recent data. (1) Our palladium-catalyzed cross-coupling has been extended to the direct coupling of alkyl phosphinates with a variety of aryl, heteroaryl, and even alkenyl electrophiles. (2) The addition of sodium hypophosphite under radical conditions is extended from alkenes to alkynes. (3) The catalytic addition of hypophosphorous compounds using palladium catalysts (hydrophosphinylation) is also discussed.

Palladium Catalyzed Cross‐Coupling Reactions for Phosphorus—Carbon Bond Formation

AbstractFor Abstract see ChemInform Abstract in Full Text.

A novel phosphorus–carbon bond formation by ring opening with diethyl phosphite of oxazolines derived from serine

A new reaction of oxazolines derived from serine with diethyl phosphite leading to ring opening products with P–C bond formation is reported. This reaction, which proceeds under neutral conditions and without the use of any halogenated intermediate, results in a mixture of racemic α- and β-phosphono alanines in an approximate 1:2 ratio, with isolated yields up to 77%. The mechanism involves the rearrangement of the oxazoline into the corresponding α-benzamido acrylate, followed by addition of the diethyl phosphite to the double bond. Since no significant transesterification is observed, this method constitutes a simple route for α- and β-phosphono amino acids bearing suitable protecting groups.

Phosphorus–carbon bond formation via reactions of triphenylphosphine with acetylene and pentamethylcyclopentadienyl coordinated to iridium(III)

Phosphorus–carbon bond is formed via: (i) the apparent HCCH insertion into Ir–P bond to produce Ir–CHCH–PPh 3 group and (ii) the activation of the ring-methyl group of the coordinated Cp * (C 5Me 5 − ) to produce Ir(η 5-C 5Me 4CH 2–PPh 3) group from reactions of iridium(III)–Cp * complexes, [Cp *IrL 3] n+ ( n=1, 2); Cp *=C 5Me 5 − ; L 3=Cl(PPh 3) 2 ( 3), (CH 3CN) 3 ( 5). The following new P–C bond containing iridium(III) complexes have been prepared: [Cp *Ir(–CHCH–PPh 3)Cl(PPh 3)] + ( 4) from 3 with HCCH; [Ir(η 5-C 5Me 4CH 2–PPh 3)(H)(PPh 3) 2] 2+ ( 6) from 5 with PPh 3; [Cp *Ir(–CHCH–PPh 3) 2(PPh 3)] 2+ ( 7) from 5 with HCCH and PPh 3; [Ir(η 5-C 5Me 4CH 2–PPh 3)(–CHCH–PPh 3)Cl(PPh 3)] 2+ ( 8) from [Ir(η 5-C 5Me 4CH 2–PPh 3)(Cl)(PPh 3) 2] 2+ ( 6- Cl) with HCCH; [Ir(η 5-C 5Me 3(1,3-CH 2–PPh 3) 2(H)(PPh 3) 2)] 3+ ( 10) from [Ir(η 5-C 5Me 4CH 2–PPh 3)(NCCH 3) 2(PPh 3)] 3+ ( 9) with PPh 3; [Ir(η 5-C 5Me 4CH 2–PPh 3)(–CHCH–PPh 3) 2(PPh 3)] 3+ ( 11) from 9 with HCCH and PPh 3.

Palladium catalyzed cross-coupling reactions for phosphorus-carbon bond formation.

Underappreciated in the realm of palladium catalyzed cross-coupling chemistry is the formation of phosphorous-carbon bonds. This tutorial review summarises a collection of important contributions in the area, providing a flavour of the many types of phosphorus species that are participants in palladium catalyzed phosphorus-carbon bond formation. Recent developments include the usage of the cross-coupling reaction for preparation of phosphine ligands and the involvement of low molecular weight phosphinic acid derivatives for the synthesis of unsaturated phosphinic and phosphonic acid derivatives. Mechanistic cycles are offered in some instances. Stereochemical issues are addressed where applicable. The literature is covered to mid 2003.

α‐Phosphono Lactone Analogues of Cytidine and Cytosine Arabinoside Diphosphates: Synthesis via Ring Closing Metathesis.

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Alpha-phosphono lactone analogues of cytidine and cytosine arabinoside diphosphates: synthesis via ring closing metathesis.

alpha-Phosphono lactone derivatives of the nucleosides cytidine and cytosine arabinoside have been prepared from the corresponding nucleoside aldehydes. The stereochemical outcome of allylation reactions with these aldehydes was found to be dependent upon both the choice of protecting groups for the 2'- and 3'-hydroxyl groups and, to some extent, the nature of the Lewis acid catalyst employed. Ultimately, conditions were found that favored either the 5'R or 5'S diastereomer from different cytidine aldehydes, and gave some stereoselectivity in additions to an aldehyde derivative of ara-C. The resulting homoallylic alcohols were used as substrates in attempted Knovenagel and Horner-Wadsworth-Emmons condensations, but elimination was found to predominate over lactone formation under the conditions employed. The desired alpha-phosphono lactones could be prepared through a reaction sequence that included ring-closing metathesis on acrylate esters of the homoallylic alcohols, followed by reduction of the resulting alpha,beta-unsaturated lactones and carbon-phosphorus bond formation on enolates generated from the saturated lactones.

Palladium‐Catalyzed Hydrophosphinylation of Alkenes and Alkynes.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Palladium-catalyzed hydrophosphinylation of alkenes and alkynes.

Various palladium catalysts promote the addition of hypophosphorous derivatives ROP(O)H(2) to alkenes and alkynes in good yields and under mild conditions. Particularly, Cl(2)Pd(PPh(3))(2)/2 MeLi, and Pd(2)dba(3)/xantphos allow for phosphorus-carbon bond formation instead of transfer hydrogenation. Commercial aqueous solutions of hypophosphorous acid can be employed successfully at ambient temperature. With styrene and terminal alkynes, the regioselectivity (linear versus branched products) can be controlled to some extent with the catalytic system employed. The methodology considerably extends upon previous routes for the preparation of H-phosphinic acids and other organophosphorus compounds.

ChemInform Abstract: Synthesis of Dinucleoside Pyridylphosphonates Involving Palladium(0)‐Catalyzed Phosphorus—Carbon Bond Formation as a Key Step.

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Transition metal mediated routes to poly(arylphosphine)s: investigation of novel phosphorus containing conjugated polymers

Poly(aryl- P-alkylphosphine)s were prepared via palladium and nickel mediated coupling and the spectral and electrochemical properties of the polymers were investigated. Palladium catalyzed carbonphosphorus bond formation was used for the preparation of poly( p-phenylene- P-alkylphoshpine)s ( 1a– b) via two routes. Low molecular weight polymers (1000–3000) were obtained by the condensation polymerization of 1,4-diiodobenzene with primary alkylphosphines. Higher molecular weight polymers (1000–14 000) were obtained via polymerization of p-bromophenylalkylphosphines ( 2a– b). Poly(4,4′-diphenyl- P-2,4,4-trimethylpentylphosphine (TMPPH 2)) ( 4b) was also prepared via two routes, the palladium catalyzed cross-coupling of 4,4′-diiodobiphenyl with primary alkylphosphines and the nickel mediated homo-coupling of bis- p-bromophenylalkylphosphines. The molecular weight of 4b was low (1000–3000) via both routes due to poor solubility. The electronic properties of polymers 1a– b were investigated with UV–vis–NIR spectroscopy and cyclic voltammetry and suggest a degree of electronic delocalization along the polymer backbone through phosphorus.

Synthesis of dinucleoside pyridylphosphonates involving palladium(0)-catalysed phosphorus–carbon bond formation as a key step

Dinucleoside 3-pyridylphosphonates, as well as their 2- and 4-pyridyl positional isomers, have been synthesised using a palladium(0)-catalysed cross coupling strategy.

Synthesis and characterization of poly(p-phenylenephosphine)s

P-Substituted poly(p-phenylenephosphine)s were prepared via palladium catalyzed carbon–phosphorus bond formation.

Reactions of σ-π alkenyl complexes [Fe 2(CO) 6(μ-alkenyl)(μ-PPh 2)] with bis(diphenylphosphino)methane (dppm); carbonyl substitution, migratory carbonyl insertion, phosphorus–carbon bond formation and cleavage, proton shift and alkenyl isomerisation reactions

Products of the thermal reactions of μ-alkenyl complexes [Fe 2(CO) 6(μ-R 1CCHR 2)(μ-PPh 2)] ( 1) ( a, R 1=R 2=H; b, R 1=EtO, R 2=H; c, R 1=H, R 2=Ph; d, R 1=Ph, R 2=H; e, R 1=R 2=Ph; f, R 1=CMeCH 2, R 2=H), with bis(diphenylphosphino)methane (dppm) are substituent dependent. Complexes 1a– c afford simple substitution products trans-[Fe 2(CO) 4(μ-alkenyl)(μ-PPh 2)(μ-dppm)] ( 2a– c); while with 1d, e, α,β-unsaturated acyl complexes trans-[Fe 2(CO) 4{μ-OC–C(Ph)CH(R 2)}(μ-PPh 2)(μ-dppm)] ( 3d, e) are the major products formed via a migratory–insertion reaction. A minor product of the reaction with 1d is [Fe 2(CO) 5{μ-Ph 2PC(Ph)CH 2}(μ-dppm)] ( 4), the result of phosphorus–carbon bond formation. Reaction of 1f also leads to phosphorus–carbon bond formation together with a 1,4-proton shift giving the μ-alkylidene complex [Fe 2(CO) 4{μ-HC–C(Me)C(Me)PPh 2}(μ-dppm)] ( 5). Dppm addition to 1c has been followed in detail, allowing a complete reaction scheme to be developed. Initial carbonyl substitution affords the η 1-dppm complex [Fe 2(CO) 5(η 1-dppm)(μ-HCCHPh)(μ-PPh 2)] ( 6). This subsequently isomerises to trans-[Fe 2(CO) 4(μ-OC–CHCHPh)(μ-PPh 2)(μ-dppm)] ( 3c) which then readily loses CO to give the μ-alkenyl 2c. Loss of CO from isomeric 3d occurs only upon prolonged thermolysis and also affords 2c, a result of α,β-alkenyl isomerisation. Further, heating 4 also yields 2c after CO loss, phosphorus–carbon bond cleavage, and alkenyl isomerisation. While the β-substituted phenylethenyl complex 2c is stable to prolonged reflux in toluene, heating isomeric cis-[Fe 2(CO) 4(μ-PhCCH 2)(μ-PPh 2)(μ-dppm)] ( 7) results in formation of the 5-electron μ-acyl complex [Fe 2(CO) 3{μ-OC–C(Ph)CH 2}(μ-dppm)(μ-PPh 2)] ) ( 8); also prepared upon heating 4. Crystal structures have been carried out on 3e and 5.