Miscellaneous Reactions of Phosphines

4 Miscellaneous Reactions of Phosphines. Procedures for the resolution of benzylcyclohexylphenylphosphine have been developed, involving adduct formation with cyclopalladated chiral amine complexes. A similar approach has also been used for the resolution of P-chiral secondary phosphines, e.g. (193). Treatment of t-butyl(di-o-tolyl)phosphine with potassium tetrachloro-palladate(ii) yields a cyclopalladated complex (194), involving chiral phos- 

4 Miscellaneous Reactions of Phosphines. - The new water soluble phosphine 

An analysis of the effects of substituents on the basicity of phosphines has been presented,and the relationship between phosphine-proton affinities and lone pair density properties explored. A scale of a-donor strengths for phosphines and related systems has been developed. The model supports the view that as a-donor strength increases, so the 7C-acceptor power declines. Theoretical approaches to the electronic structures of phosphirane and 1,3-diphosphe- 

1 Preparation. - Fluorophosphines have been obtained from the reactions of the related chlorophosphines with trimethyl tin fluoride. Phenyl(isopropyl)-fluorophosphine has been resolved via a chiral amine-palladium(II) complex, providing the first example of the resolution of a free fluorophosphine chiral at phosphorus. This compound racemises at 20 °C in benzene solution over six hours. The neat compound rapidly decomposes by redox disproportionation. The same approach has been used for the resolution of the related chloro-phosphine, but the optically active compound could not be liberated unchanged from the crystallised diastereoisomeric palladium complex. The dihalo-genophosphines 

4 Miscellaneous Reactions of Phosphines.- The basicities of a series of bidentate phosphines have been determined by a study of their enthalpies of protonation with trifluoromethanesulphonic acid in 1,2-dichloroethane. Ring-opening of sultones via nucleophilic attack by nitrogen occurs on treatment with tri-(2-pyridyl)phosphine, with the formation of the water-soluble phosphine systems (91). A novel aldehyde-olefination procedure is afforded by the reactions of aldehydes, diazomethanes, and tertiary phosphines in the presence of a catalytic amount of the powerful Lewis acid methyltrioxorhenium. Attempts to prepare carboxyphenylphosphines by the ring metallation of triphenylphosphine followed by 

4 Miscellaneous Reactions oj Phosphines. Gas phase pyrolysis of diallyl(4-fluorophenyl)phosphine and allyl(/-butylamino)phenylphosphine results in the formation of 1-(4-fluorophenyl)-1-phosphabutadiene and 1-phenyl-2( - 

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Miscellaneous Reactions of Phosphines.- The role of chiral phosphines as ligands in the catalysis of reactions leading to the formation of chiral products has been reviewed.1111 A procedure for the determination of the enantiomeric excess in chiral phosphines has been developed, based on 13C n.m.r. studies of the diastereoisomeric complexes formed by phosphines with the chiral pinenyl nickel bromide complex. 111 Studies of the sulphonation of triphenylphosphine and of chiral arylphosphines have been reported in attempts to prepare water soluble ligands which aid... 

Miscellaneous Reactions of Phosphines. The effects of substituents at phosphorus on the basicity and donor properties of phosphines have continued to attract the attention of the theoretical chemists. Among recent papers are a quantum chemical study of the protonation of phenylphosphine and its... 

Miscellaneous Reactions of Phosphines.- Theoretical treatments have appeared of a number of strained heterocyclic phosphine systems, notably phospha[3]radiaIene (148), triphospha[l, 1, l]propellane (149), and the tetraphosphacubane system (150). The reactivity of tetrakis-r-butyltetraphosphacubane has been studied in superacid media, with respect to protonation, alkylation, and alkynylation. Stable monophosphonium ions have been characterised. ... 

D. Miscellaneous.—A further study of the reactions of diphenyl-phosphine oxide with tetracyclone has confirmed that the reaction yields the oxide (30) under mild, basic conditions, and that the reaction is thermally reversible. The displacement of halogen from phosphorus by amino-compounds has been used in the synthesis of a number of aminofluoro-phosphine oxides (31), and of A-methyl-AA-bis(dichlorophosphinyl)-amine (32). ... 

Miscellaneous. A number of reports of the synthesis of unusual heterocyclic phosphines have appeared. Improved procedures for the synthesis of l,3,5-triaza-7-phospha-adamantane (48) have been reported,40-41 and the triazaphosphahomo-adamantane (49) has also been prepared.42 Routes to the large ring phosphacyclo-alkanes (50) have been described,43 and the bicyclic diphosphine (51) has been isolated from the reaction of white phosphorus with o-dichlorobenzene in the presence of transition-metal halides.44... 

Other miscellaneous syntheses that have benefited from the introduction of dppf to the catalytic mixture include the coupling reactions of aryl triflates or halides with ketene trimethylsilyl acetals [165], The catalyst mixture is [Pd(OAc)(i -C4H7)]2/LiOAc/phos-phine. In this case, nucleophilic activation of the Si-O bond of the acetal enables an Si-Pd transmetalation to give a a-complex 52 without necessitating a phosphine... 

Miscellaneous Methods of Preparing Phosphines. Approaches to the synthesis of specific types of organophosphine have been reviewed, covering phosphinoaryloxazolines, /ra j-2,5-disubstituted phospholanes, " new chiral phosphines which have been reported since 1990, chiral hydroxyphos-phines, and phosphorus-sulfur donor ligands.The uses of phosphine (PH3) in the synthesis of organophosphines has also been reviewed. A direct route for the synthesis of arylphosphines is offered by the reaction of... 

Miscellaneous Methods of Preparing Phosphines. Palladium-catalysed formation of phosphorus-carbon bonds continues to be developed as a useful route to organophosphines. The reactions of primary or secondary phosphines with aryl- or vinyl-halides in the presence of a palladium catalyst, usually palladium acetate or a zerovalent palladium-phosphine complex, have been used in the synthesis of steroidal phosphines, e.g., (128), the cationic diphosphine system... 

Miscellaneous Reactions.—-Mixed alkylalkoxydiphosphines (103) have been prepared from secondary phosphites and chlorophosphines under basic conditions the alternative reaction between secondary phosphine and chloro-phosphite gave much lower yields. Surprisingly, oxidation of (103) with... 

With Miscellaneous Compounds. Several mechanistic studies have been performed recently on reactions of "auxiliary stabilizers with 4-chloro-2-hexene, both in the presence and in the absence of metal salts (82,87,88, 89,90). The stabilizers used were phosphites (82,87), phosphines (82,87), epoxides (88), 2-phenylindole (89), and the bis(j8-aminocrotonate) ester of 1,4-butanediol (90). Important mechanistic features delineated in this work included substitutive removal of allylic... 

Miscellaneous Reactions.—Details have appeared of a series of rearrangements of the phosphine oxides (41a, b) in which the diphenyl-phosphinyl group migrates to a carbonium centre to the phosphorus. 

Miscellaneous. A kinetic study on the reaction of oxaziridines with tri-n-butylphosphine suggests that the attack of phosphine on the oxaziridine oxygen atom is concerted and proceeds via a transition state of the type... 

Miscellaneous Reactions. Bromodimethylborane can also be used to convert dialkyl, aryl alkyl, and diaryl sulfoxides to the corresponding sulfides (eq 15). Typically, the sulfoxides are treated with 2.5 equiv of Me2BBr in dichloromethane at —23 °C for 30 min and at 0°C for 10 min. Bromine is produced in the reaction and must be removed in order to avoid possible side reactions. This is accomplished by saturating the solution with propene prior to introducing the reagent or by adding cyclohexene. Phosphine oxides and sulfones failed to react under the conditions used to deoxygenate sulfoxides. 

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