Halogenophosphines phosphines

A. From Halogenophosphine and Organometallic Reagent.—Mesityl-magnesium bromide reacts with chlorodiethylphosphine and dichloroethyl-phosphine at — 10 °C in THF to yield mesityldiethylphosphine and dimesitylethylphosphine respectively. ... 

Two papers have appeared on the reactions of halogenophosphines with tervalent phosphorus compounds. In a detailed study of the reactions at 20 °C of a range of tertiary phosphines with phosphorus trichloride, dichlorophenylphosphine, and chlorodiphenylphosphine, it has been shown that, in general, 1 1 adducts are formed, provided that the tertiary phosphine is a good nucleophile. With diphenylchlorophosphine, for example, an adduct (18) is formed with dimethylphenylphosphine, but not with diphenylmethylphosphine, although the relative importance of steric and electronic factors remains to be established. The related reactions of phosphorus trichloride and of dichlorophenylphosphine are much more complex, and the initial crystalline products are not amenable to analysis. The reactions at 280 °C of a similar system have been shown to lead to halogen exchange, e.g. the conversion of (19) to (20). 

Preparation.—From Halogenophosphine and Organometallic Reagents. The cyclo-pentadienylphosphines (1) have been obtained from the reaction of cyclopenta-dienylthallium with chlorophosphines in ether.1 Diphenyl(4-pyridyl)phosphine (2) is prepared from 4-pyridyl-lithium and chlorodiphenylphosphine,2 and an improved procedure for the synthesis of tri-(2-pyridyl)phosphine (3) from 2-pyridyl-lithium and phosphorus trichloride has been reported.3... 

The basicity of halogenophosphines has attracted some attention this year. A careful study of the protonation of several halogenophosphines (6) has led to the characterization by 31P n.m.r. of phosphonium species, such as (7).12 These salts show 31P shifts to relatively high fields, and large Vph values e.g., (7) has 1190 Hz.12 Attempts have been made to correlate phosphine basicity with Vpb values in borane complexes,13 and, in turn, to correlate Vpb with electrostatic interactions in the phosphorus-boron bond.13 From such correlations, the authors deduce that this bond is dominated by electrostatic contributions, and not by other factors, such as -bonding. 

Reactions of Halogenophosphines.- On standing for several days in deuteriochloroform solution, the difluorophosphine (90) undergoes an unusual disproportionation reaction to form the related aryltetrafluorophosphorane and the dihalogenodiphosphine (91) 232 Phosphorus-phosphorus bond formation has also been observed in the reactions of chloro(phenyl)phosphines with aluminium chloride, with the formation of phosphinohalogeno-phosphonium salts, e.g., (92)233,234 also in the reaction of... 

The cyclic phosphinate (96) has been isolated from the reaction of dichloro(methyl)phosphine with the ethoxycarbonylimine derived from hexafluoroacetone. Treatment of trichloro(organo)phosphonium-hexafluorophosphate salts with dichloro(diethylamino)phosphine results in the halophosphonium salts (97). Some reactions of dichloro(-)menthylphosphine have been reported.As usual, nucleophilic displacement reactions of halogenophosphines have received attention as routes to new systems of interest as ligands.Of particular interest in this connection is a report of the synthesis of the phosphorus-functionalised calixarenes (98). Only one chlorine atom of dichloro(phenyl)-phosphine is replaced on treatment with an excess of dicyclohexylamine, enabling the stepwise synthesis of the chiral aminophosphines (99), described as air-stable solids. 

Routes to the dihalomethylene systems (149) have been developed which involve the reactions of halogenophosphines with tetrahalo-genomethanes in the presence of phosphines,and also phosphine-induced dechlorinations of trichloromethylchloro-... 

As this area was not covered in Volume 31, the present chapter provides an overview of the literature published over the two years between July 1998 and June 2000. The report is structured in terms of the principal classes of tervalent phosphorus acid derivatives, viz halogenophosphines, tervalent phosphorus esters, and amides. Attempts have been made to minimise the extent of overlap with other chapters, in particular those concerned with the synthesis of nucleic acids and nucleotides to which the chemistry of tervalent phosphorus esters and amides contributes significantly (see Chapter 4), the use of known halogenophosphines as reagents for the synthesis of phosphines (see Chapter 1), and the reactions of dialkyl- and diaryl-phosphite esters, in which the contribution of the phosphonate tautomer, (R0)2P(0)H, is the dominant aspect. 

A number of non-routine reactions of halogenophosphines are worthy of note. The first aliphatic phosphenium cation featuring a phosphorus-sulfur bond (17) has been obtained by treatment of the chlorophosphine (18) with aluminium trichloride in dichloromethane solution. A new synthesis of acyclic chiral t-phosphines has been developed which employs selective, sequential alkylation of the chloro(amino) phosphines (19) by Grignard and organolithium reagents. The key intermediates (19) are readily prepared by the... 

Preparation.—From Halogenophosphines and Organometallic Reagents. A series of trimethylsilylcyclopentadienylphosphines, e.g. (1), has been prepared from the appropriate trimethylsilylcyclopentadienyl-lithium and halogenophosphine. Similarly, the reaction of pentamethylcyclopentadienyl-lithium with chlorodimethyl-phosphine gives the phosphine (2), which is reported to be thermally stable. ... 

Two unusual fluorinated phosphines, (6) and (7), have been prepared by the reactions of organolithium reagents with appropriate halogenophosphines. ... 

Preparation.—From Halogenophosphine and Organometallic Reagents. An improved synthesis of trimethylphosphine from phosphorus trichloride and methyl-lithium at —78 °C has been described. Another improved high yield synthesis of the same phosphine uses the reaction of triphenyl phosphate with methylmagnesium iodide. Other trialkylphosphines have also been prepared by this latter method. 

Other physical aspects of halogenophosphines include a conformational study of the phosphetan (15), and of the phosphines (16), from variable-... 

Preparation.—Little significant preparative work has appeared this year. The preparation - of phosphoranes from halogenophosphines and carbonyl compounds is discussed above, and the conversion - of certain of these into phosphine oxides is discussed in Chapter 4. The perfluorophenylphosphorane (76) has been prepared. Dichlorotriethylphosphorane (77) is formed as a... 

P,P-diphosphines, and halogenophosphines, have given a range of new trifluoromethylphosphines, e.g., the chiral secondary phosphines (98). These compounds are also accessible by insertion of perfluoroalkylphosphinidenes, R P , into the P=P bond of... 

Tetra- and pentachloro- and tetrabromo-complexes of Tc(IV) containing different phosphines were prepared by reaction of technetium tetrahalogenide with the pertinent phosphine [356] or by refluxing TcOj with the phosphine in ethanol in the presence of hydro-halogenic acid [386]. Halogenophosphine complexes are summarized in Table 12.12. A. 

Metallation of i,3,5-tricyanocyclohexane, followed by treatment with chlorodiphenylphosphine results in the formation of the m-triphosphine (IS), in which all the phosphino centres are available for coordination in a facial manner. The organolithium-halogenophosphine route has been applied extensively in the synthesis of ferrocenyl phosphines. New approaches for asymmetric synthesis of... 

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