Experimental and Quantum Chemical Studies of 2-Phosphinylphenol Derivatives

Carbon-oxygen bonds ortho to a phosphoryl group in triarylphosphine oxides undergo cleavage when the oxides are either fused with potassium hydroxide or treated with potassium tert-butoxide in refluxing toluene, presumably through a nucleophilic addition-elimination mechanism. Thus, bis(2-hydroxyphenyl)phenylphosphine oxide is produced along with the expected 2-phenoxyphenyl(phenyl)phosphinic acid from 10-phenyl-10H-phenoxaphosphine 10-oxide. The latter starting material is also produced, together with bis(2-hydroxyphenyl)phenylphosphine oxide, when bis(2-methoxyphenyl)phenylphosphine oxide is fused with potassium hydroxide. Fusion of bis(2-methoxyphenyl)phenylphosphine oxide with sodium hydroxide, however, yields 2-hydroxyphenyl(phenyl)phosphinic acid. Ab initio quantum chemical studies confirm that the downfield ³¹P chemical shift that is observed in 2-phosphinylphenols is due to hydrogen bonding to the phosphoryl group.     

Preparation of Bicyclic Secondary and Tertiary Phosphines from Radical Addition of Phosphine and Primary Phosphines to Limonene

Abstract

In the presence of a free radical initiator, limonene combines with a primary phosphine to yield a 1:1 adduct (I). Initially the addition takes place at the isopropenyl moiety. The resulting secondary phosphine subsequently undergoes an intramolecular addition to produce two isomeric 2-alkyl-4,8-dimethyl-3-phosphabicyclo [3.3.1]nonanes (II, III) in >85% yield. Analogous bicyclic secondary phosphines are formed by free radical addition of phosphine to limonene. Yields are slightly lower due to the addition of the reactive secondary phosphines to a second mole of limonene.     

Synthesis and Stereochemical Studies of Derivatives of 1,4-Dimethyl-2-phosphabicyclo[2.2.1]heptane

Abstract

1,4-Dimethyl-2-phenyl-2-phosphabicyclo[2.2.1]heptane 2-oxide 1 was prepared by the reaction of 2,5-dimethyl-1,5-hexadiene with PhPCl₂-AlCl₃: stereo-assignments of the exo and endo isomers were established by ¹³C NMR spectroscopy (using lanthanide shift reagents) and by x-ray crystal structures. The isomers of 1 were separately reduced (phenylsilane) to give the phosphine derivative; in turn the phosphines were thermally equilibrated at 190°C to give a predominance (70%) of the exo-phenyl isomer.     

Addition of secondary phosphines to a vinyl ether of diacetone-d-glucose: a new approach to optically active phosphines and their derivatives

Secondary phosphines react readily with a vinyl ether of diacetone-d-glucose under radical initiation conditions to give, in high yield, anti-Markovnikov adducts, diorganyl{2-[3-O-(1,2:5,6-di-O-isopropylidene)-d-glucofuranosyloxy]ethyl}phosphines, which oxidize almost quantitatively upon reacting with air oxygen or elemental sulfur to form the corresponding optically active phosphine oxides or sulfides.     

Gas-phase thermolysis of diallyl(4-fluorophenyl) and allyl(t-butylamino)phenyl phosphines

Dially(4-fluorophenyl)phosphine and allyl(t-butylamino)phenylphosphine were pyrolyzed in a stirred-flow reactor at 340–420°C/9–19 Torr, using toluene as carrier gas. The primary reaction products were propene, 1-(4-fluorophenyl)-1-phosphabutadiene, and 1-phenyl-2-t-butyliminophosphine. The phosphorus-containing products gave rise to [4 + 2] and [2 + 2] cycloaddition products, respectively. The consumption of these phosphines showed first-order kinetics, with the rate coefficients following the Arrhenius equations: Dially(4-fluorophenyl)phosphine: k(s⁻¹) = 10^9.00±0.32 exp (- 122 ± 4 kJ/mol RT) Allyl(t-butylamino)phenylphosphine: k(s⁻¹) = 10^9.04±0.25 exp (-113 ± 3 kJ/mol RT) The results support a six-center cyclic transition-state unimolecular elimination reaction mechanism for both reactants. © 1997 John Wiley & Sons, Inc.     

Oxidative-Rearrangement Reactions of σ3, λ3 Dialkyl(Silylamino)Phosphines with Chlorophosphines; Formation of a P–P Bond Via a New Road to Phosphinophosphoranimines

Abstract:

Chlorophosphines react with trivalent (silylamino)phosphines via a direct oxidative addition process with elimination of trimethyl silyl chloride to produce phosphino-phosphoranimines with concomitant formation of a P-P bond. Oxidation of the phosphine center with sulfur and an exchange transformation of the phosphine are discussed.     

MECHANISM OF THE REACTION OF DIPHENYL N-BROMOSULFILIMINE WITH SULFIDES,PHOSPHINES AND TERTIARY AMINES

Abstract

The mechanism of the reactions of diphenyl N-bromosulfilimine (I) with such nucleophiles as sulfides, phosphines and tertiary amines was investigated. In the presence of water, (I) reacts with sulfides or phosphines to afford the corresponding sulfoxides or the phosphine oxides in moderate yields; however, the reaction with tertiary amine gave only the N-t-aminosulfilimine derivative. The effect of ring size in the reaction with cyclic sulfides suggests that the reaction proceeds via initial bromine transfer from the nitrogen atom to the sulfur atom of the cyclic sulfides followed by S_N2 type substitution of bromide on the sulfur atom of the cyclic sulfide with the sulfilimino group. The phosphine oxide obtained in the reaction of (I) with optically active methyl n-propyl phenyl phosphine was racemized but retained a small portion of the optical activity. In the case of tertiary amines, even 1,4-diazabicyclo-(2,2,2)-octane (DABCO), in which the back side of the nitrogen atom is blocked, reacted smoothly to afford the corresponding ammonium salts, suggesting the reaction to be of S_N2 type on the nitrogen atom of the sulfilimine.     

Cyclopentannulation on 3-phospholenes: an expedient route to the 2-phosphabicyclo[3.3.0]octene ring system

Treatment of 1-phenyl-3-phospholene derivatives with 2 equiv. of LDA followed by quenching the metallated intermediates with 1,3-dihaloalkanes affords 2-phosphabicyclo[3.3.0]oct-3-ene derivatives in good yield. The annulation reactions are highly regio- and stereoselective and lead to the formation of exo-Ph-P substituted products exclusively. Reduction of the resulting bicyclic phosphine oxides by phenylsilane gives the corresponding phosphines with complete retention of configuration at P. Application of this annulation procedure to acyclic allylic substrates leads to the corresponding monocyclic annulation products.     

Synthesis and X-ray structural characterization of mono(aminophosphine) derivatives of molybdenum hexacarbonyl, Mo(CO)5L {L?=?P(NC5H10)3, P(Ph)(NC4H8O)2 or P(Ph){N(i-C3H7)2}(NC4H8O)}

Equimolar reactions of molybdenum hexacarbonyl with tris(piperidino)phosphine (L1), bis(morpholino)(phenyl)phosphine (L2), and (Di-isopropylamino)(morpholino)(phenyl) phosphine (L3), which are examples of symmetrically and unsymmetrically substituted tertiary(amino)phosphines, afford the corresponding mono derivatives, Mo[P(NC₅H₁₀)₃)](CO)₅ (1), Mo[P(Ph)(NC₄H₈O)₂](CO)₅ (2), and Mo[P(Ph){N(i-C₃H₇)₂}(NC₄H₈O)](CO)₅ (3) in moderate yields as air stable crystalline solids. In the case of L1, some amount of trans-bis derivative, Mo[P(NC₅H₁₀)₃)]₂(CO)₄ (4), was also isolated. X-ray structures of 1, 2, and 3 have been determined. Compounds 1 and 2 crystallize in the monoclinic system with space group P21/c, while 3 crystallizes in the triclinic system with space group Pī. While the Mo-P and Mo-C_ax bond distances in these complexes are comparable with those of other P-C bonded phosphines, the presence of chiral phosphine seems to induce a relatively weaker interaction with the molybdenum center. Intermolecular hydrogen bonding is seen in compound 1.     

Acetylenchemie, 14. Mitt.: PTC-Umsetzung von 9(10H)-Acridinon mit 3-Chlor-3-phenyl-1-propin und 3-Brom-1-phenyl-1-propin

Summary Reaction of 9(10H)-acridinone (2) with 3-chloro-3-phenyl-1-propyne under PTC conditions affords 1-methyl-2-phenyl-6H-pyrrolo[3,2,1-de]acridin-6-one (1 b), 10-(2-chloro-1-methyl-2-phenyl-ethenyl)-9(10H)-acridinone (4), 10-(3-phenyl-1-propynyl)-9(10H)-acridinone (7), and 10-(4-methylene-2,3-diphenyl-2-cyclobuteneylidenemethyl)-9(10H)-acridinone (5). The structure of the last compound which crystallizes in the triclinic system with the space group , was confirmed by X-ray diffraction. Under the same conditions 10-(3-phenyl-2-propynyl)-9(10H)-acridinone (3) and 10-(3-phenyl-1-propynyl)-9(10H)-acridinone (6) were obtained from 9(10H)-acridinone (2) and 3-bromo-1-phenyl-1-propyne.

     

Synthesis and Structure of Some 1,3,2-Oxazaphospholenes

Abstract

The reaction of trialkyl phosphites and phosphines with o-quinones result in the formation of oxyphosphoranes [1]. In an effort to prepare o-quinone monoimine metal complexes with amine [2] and phosphine ligands it has been found that in the reaction either of o-quinones (1) with phosphines in the presence of ammonia or of o-quinone monoimines (2) with phosphines 1,3,2-oxazaphospholenes (3) are formed in good yields.     

New Heterodonor Phosphine Ligands

Abstract

In our studies we have synthesized three novel mixed ortho- and pura substituted phenyl phosphines: pSoOOP, pOoSSP and pSoSSP and a new phosphine containing pyridyl units: pS2Py. Also pOoOOP and pO2Py, which have been previously mentioned in patent literature[1,2] were prepared.     

NMR studies of dynamic behavior of dialkyl(acetylacetonato)bis(tertiary phosphine)cobalt(III) and related complexes in solution

The ¹H, ³¹P and ¹³C NMR spectra of cis-dialkyl(acetylacetonato)bis(tertiary phosphine)cobalt(III) complexes were obtained in several solvents. These complexes have an octahedral configuration with trans tertiary phosphine ligands. The coordinated tertiary phosphine ligands are partly dissociated in solution. One of the phosphine ligands in CoR₂(acac)(PR₃′)₂ can be readily displaced with pyridine bases to give pyridine-coordinated complexes. From observation of the ¹H and ³¹P NMR spectra several kinetic and thermodynamic data for exchange reactions and displacement reactions of tertiary phosphines were obtained.     

Binaphthyl-Substituted Chiral Phosphines and Oxides from Binaphthophooles and Nucleophiles

Binaphthophospholes 1 are the starting compounds for the synthesis of chiral phosphine oxides 3 or phosphines 4 via reaction of phospholium salts 2 with nucleophiles. The binaphthyl residue acts as a stereochemical probe for monitoring the integrity of the phosphorus stereocenter.     

Diphosphirenium Salt: A New Versatile Ligand

Abstract

Strained aromatic cyclopropenylium cations are versatile ligands for transition metal complexes: η¹-, η ²- and η³-coordination modes have been observed. Here we report on the ligand properties of the related diphosphirenium salt A[1]. Treatment of a dichloromethane solution of diphosphirenium salt A with an equimolar amount of palladium tetrakis(mpheny1phosphine) afforded 1,3-diphospha-2-bis(uiphenyl-phosphine)pallada(II)cyclobutene B in 70% yield. Exchange of the triphenylphosphine ligands occurs with various phosphines, and the structures of these new diphospha-metallacyclobutenes have been elucidated by NMR and in one case by a single X-ray diffraction study [2].     

Chiral Phosphines: The Effect of Asymmetric Carbon Centers α or β to Phosphorus on the 31P NMR Spectra

Abstract

Chiral alkylphosphines containing asymmetric carbon centers either alpha or beta to the phosphorus are formed from the free radical addition of phosphine to prochiral olefins. The phosphorus NMR spectra of the primary phosphines have only one signal for the enantiomeric pair while the spectra of the secondary phosphines have three signals in a 1:2:1 ratio. This is the statistical ratio expected for the enantiomeric pair and two meso forms. Four enantiomeric pairs of tertiary phosphines can be formed from one prochiral olefin. One pair has alkyl groups of the same configuration while the remaining pairs have mixed configurations. The phosphorus NMR spectra show two signals in a 1:3 ratio. Dilution of the secondary phosphines with a polar solvent results in only one signal in the phosphorus NMR spectra. The chemical shifts and diluent effect can be explained in terms of the gamma shielding effect (1).     

1,2- and 1,3-diphosphetanes from alkylidenephosphines

Abstract

Alkyl- or arylbis(trimethylsilyl)phosphines as well as tris(trimethylsilyl)phosphine and the corresponding arsines react with acyl chlorides to give [1-(trimethylsiloxy)alkylidene]phosphines 1 and -arsines 2; most of their 2,2-dimethylpropylidene derivatives are thermally stable at room temperature. With the same class of phosphines as starting compounds and carbon disulfide [bis(trimethylsilylsulfano)methylidene]phosphines 3 are formed, whereas [(dialkylamino)methylidene]-4 and [diarylmethylidene]phosphines 5 or the corresponding arsines 6 and 7 can be obtained from acyl amides or ketones.¹     

An unexpected molybdenum(0) complex with “MoP6” coordination: crystal structure of [Mo{P(CH2CH2PPh2)3}2] · C5H10

The reaction of trans-[Mo(N₂)₂(PPh₂Me)₄] with the tripodal phosphine tris(2-diphenylphosphinoethyl)phosphine, PP₃, in benzene has been studied. The product was recrystallized from a mixture of benzene and petroleum ether to give [Mo(PP₃)₂]·C₅H₁₀, whose crystal structure shows a distorted octahedral “MoP₆” coordination with both phosphines acting as tridentate ligands.     

Stereoselective Synthesis and Complexation of a New Chiral Hybrid Phosphine-Phosphine Oxide Ligand from (S)-(+)-Prolinol

Abstract

The synthesis and the complex formation of chiral heterotopic ligands with two different binding sites each capable of bonding a different type of metal are described. The action of bis(dimethylamino) aryl phosphine on (S)-(+)-prolinol gives rise to the kinetic stereoisomer (2S,4S)-2-phenyl-1,3,2-oxazaphospholidine 1 and the thermodynamic stereoisomer (2R,4S)-2-phenyl-1,3,2-oxazaphospholidine 2. 1 is then totally converted into 2 at the end of the reaction. The Michaelis Arbuzov reaction of 2 with benzylbromide affords (R_p)-benzylaryl-(2-(S)-bromomethyl pyrrolidine-1-yl) phosphine oxide 3 in 80% yield. Compound 3 is an ideal chiral precursor for the synthesis of chiral hybrid phosphine-phosphine oxide ligands. The bromide atom is smoothly displaced by lithium diphenylphosphide to afford in 80% yield (R_p)-benzylaryl-(2-(S)-diphenylphosphinomethylpyrrolidine-1-yl) phosphine oxide 5. These reaction are proved to be totally stereoselective : the Michaelis Arbuzov reaction does not change the configuration at C2 in the proline ring. The relative configuration (R_p) of 5 (aryl = phenyl) was determinated by X-ray diffraction, from the known configuration of (S)-(+)-prolinol.     

Atom-Economic Synthesis of Tris[2-(organylthio)ethyl]phosphine Oxides from Phosphine and Vinyl Sulfides

Abstract

Phosphine, generated from elemental phosphorus in the system KOH-toluene-H₂O, reacts with vinyl sulfides under free radical conditions (AIBN, dioxane, 65–70°C, atmospheric pressure) to form regiospecifically tris[2-(organylthio)ethyl]phosphines, which are readily oxidized in air to corresponding tris[2-(organylthio)ethyl]phosphine oxides.