Phosphine, Tris trimethylsilyl

TRIS(TRIMETHYLSILYL)PHOSPHINE AND LITHIUM BIS(TRIMETHYLSILYL)PHOSPHIDE BIS-(TETRAHYDROFURAN) 

Submitted by GERD BECKER, HELMUT SCHMIDT, GUDRUN UHL, and WERNER UHL  

Checked by MANFRED REGITZ, WOLFGANG RdSCH, and UWE-JOSEF VOGELBACHER  

Tris(trimethylsilyl)phosphine and its more reactive derivative lithium bis-(trimethylsilyl)phosphide-2tetrahydrofuran are very useful reagents for the preparation of compounds with a single or a multiple element phosphorus bond. They react readily with various element halides, with carboxylic acid chlorides, and with carboxylic esters, as well as with other organic electrophiles via a substitution of lithium and/or a cleavage of the weak polar Si-P bonds. 

These solvents must be deoxygenated and freed from traces of water before use by refluxing over sodium wire in the presence of benzophenone in a slight stream of argon. When the color has changed to deep blue, the solvent is distilled off. Pentane is purified in a similar way with lithium tetrahydrido-aluminate. 

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Carbon-phosphorus double bonds are also formed in addition reactions of tris(trimethylsilyl)phosphine 1692 (which can be readily prepared from white phosphorus, sodium, and TCS 14 [13a,b,c]) to give oxazohum fluorides 1691 which then give the azaphospholes 1694, via 1693 [3, 14]. On addition of 1692 to 1695, the diazaphosphole 1696 [3, 15] is prepared, whereas l,3-azaphospholo[l,2a]pyridines 1698 [16] are formed from 1692 and 1697, and 1,3-thiaphospholes 1700 are formed from the dithiohum fluorides 1699 [17]. l,3-Benzodiphospholyl anions 1703 are generated by reaction of acid chlorides with the dihthium salts 1701, via 1702 [18] (Scheme 11.3). 

Use of tris(trimethylsilyl)phosphine as the phosphorus furnishing reagent in condensation reaction with a-diazocarboxylic chlorides (7) gave 2-trimethylsilyl-[l,2,3]diazaphospholes (9) in good yields (Scheme 3) [18],... 

Organosilylphosphines are conveniently prepared by cleavage of alkyldiaryl-phosphines with lithium in THF, followed by treatment with chlorotrimethyl-silane,15 and tris(trimethylsilyl)phosphine has been prepared from the reaction of chlorotrimethylsilane with a mixture of sodium and potassium phosphides.16... 

Silyl- and Related Phosphines.—A new preparation of tris(trimethylsilyl)phosphine (61) from white phosphorus has been reported.62 Lithium derivatives of (61) may be prepared by cleavage with butyl-lithium,63 using glyme as solvent. 

Tris(trimethylsilyl)phosphine, 3229 Tris(trimethylsilyl)silane, 3231... 

Bis-(trimethylsilyl)phosphine and trimethylsOylphosphine are also formed by the hydrolysis of tris-(trimethylsilyl) phosphine with the appropriate amount of water in diglyme or tetrahydrofuran ... 

A simUar phosphamethin-cyanine synthesis starting from tris-trimethylsilyl-phosphine has been described by Markl. Using this procedure, arsamethin-cyanines can also be prepared from tris-trimethylsilyl-arsin... 

Method B Reaction of Pyrylium Salts with Tris-(trimethylsilyl)-phosphine... 

A phosphorus atom replaces oxygen when the pyrylium salt is treated with one of several nucleophilic phosphines for example, tris(trimethylsilyl)phosphine gives 2,4,6-triphenylphosphorin (80) (67AG(E)458). The earliest use of 2,4,6-tri-r-butylpyrylium tetrafluoroborate (81) was its conversion to the corresponding phosphabenzene (82) (68AG(E)461). 

Tris(trimethylsilyl)phosphine, 3223 Tris(trimethylsilyl)silane, 3225... 

A convenient synthesis of phosphinines 185 involves the reaction of pyrylium salts 184 with either an excess of tris(trimethylsilyl)phosphine in acetonitrile, or alternatively with PH3 under pressure at 110°C <2001CEJ3106>. Better yields are often obtained using the direct reaction with PH3 (Equation 37). 2-t-Butyl phosphinines 187 can be prepared by reaction under pressure of /-butylphosphaacetylene with the a-pyrone 186 (Equation 38). 

Tris(trimethylsilyl)phosphine l13 reacted with pyrylium salts in the presence of potassium fluoride to give thermodynamically stabilized phosphabenzene derivatives (X3-phosphinines) (equation 4)14. In addition, various heterophosphabenzenes and... 

Dimethyl-1-(trimethylsiloxy)propylidene(trimethylsilyl)phosphine 8 is prepared by the reaction of pivaloyl chloride with tris(trimethylsilyl)phosphine (see Protocol 3). 

Caution All operations must be carried out in the absence of oxygen and moisture. All reaction vessels must be heated with a heat-gun, evacuated repeatedly at 5 x 10-3 mbar, and purged with argon prior to use. For all manipulations of the air-sensitive materials, the Schlenk technique is employed. Pivaloyl chloride is harmful on inhalation. Tris(trimethylsilyl)phosphine 17 is toxic and extremely sensitive towards oxygen and water and highly inflammable upon contact with air and organic materials. 

To a dried three-necked round-bottomed flask (500 mL) with magnetic stirrer bar, a reflux condenser (closed by blubber), a pressure-equalizing dropping funnel (250 mL) and an argon inlet, add dry /7-pentane (200 mL) and tris(trimethylsilyl)phosphine (50 g). 

Tris(trimethylsilyl)phosphine is prepared by the reaction of white phosphorus with sodium naphthal-... 

As an example we describe here the synthesis of the l//-l,2,4-diazaphosphole 22 that, on account of its easy accessibility and as parent compound of the class, is of general interest. The synthesis proceeds through condensation of the cation 21. The reaction of 21 with hydrazine involves cleavage of an ammonium salt to furnish the phosphole 23.46 The cation 21 is obtained via a methanaminium chloride—generated as an intermediate from N, A-dimethylformamide and oxalyl chloride—by condensation with tris(trimethylsilyl)phosphine. 

Caution Oxalyl chloride is harmful on inhalation. Carbon monoxide evolved in the first step is toxic. Tris(trimethylsilyl)phosphine is toxic and extremely sensitive towards oxygen and water. It is spontaneously inflammable upon contact... 

Place the tube in a water bath and add slowly from the pressure-equalizing dropping funnel tris(trimethylsilyl)phosphine (8.90 g, 35.5 mmol) at room temperature with stirring over 30 min. The colour of the mixture changes to orange and finally to brown. 

The sterically demanding phosphine tris(trimethylsilyl)phosphine, P(SiMe3)3, proved to be very important in the development of the chemistry of the Al-P bond. A number of aluminum-phosphorus adducts were reported in the last decade. In particular, Cl3Al-P(SiMe3)3 toluene and Br3APP(SiMe3)3 toluene, with Al-P bond distances of 2.392(4) A and 2.391(6) A, respectively, were reported. These virtually identical Al-P bond distances are extremely short. The aluminum atoms in both complexes may be described as four-coordinate tetrahedral. 

An informative reaction in this regard involves that of trimethylgallium with the sterically demanding phosphine, tris(trimethylsilyl)phosphine (Me3Si)3P (Equation (16)) ... 

Caution. Sodium and particularly potassium react violently with water and may ignite in air. The incrustations of potassium may be explosive only potassium with little or no incrustation should be cut, and care should be taken to ensure anhydrous conditions. Sodium-potassium alloy as well as malodorous tris(trimethylsilyl)phosphine are pyrophoric and extremely sensitive to moisttve. Therefore the entire procedure must be carried out in an atmosphere of dry argon in a well-ventilated fume hood. In case of emergency a sand bath should be available to catch the liquid alloy. 1,2-Dimethoxyethane and tetrahydrofiiran (THF ) may form explosive peroxides. Only fresh, peroxide-free material should be used. 

Caution. On cooling, the pure distillation product may crystallize rapidly and block the apparatus. The residues from the filtration and distillation may contain either pyrophoric sodium-potassium alloy or tris(trimethylsilyl) phosphine and trimethylsilyl-substituted cyclic polyphosphines. For safety reasons all residues must be treated very cautiously with a mixture of ethanol and petroleum ether (1 10) under an inert atmosphere in a well-ventilated fume hood. 

Tris(trimethylsilyl)phosphine is a colorless compound with a melting point near room temperature. Characteristic NMR data for a DME solution are 5,ih) 0.30 Jp = 4.4 cps 5,3ip,-251. In reactions with alcohols and water bis(trimethylsilyl) and (trimethylsilyl)phosphine can be synthesized acetyl chloride in a molar ratio of 1 3 gives triacetylphosphine. For the important reaction with 2,2-dimethylpropionyl chloride see Section 49. 

Fig. 3. Filtration of the reaction mixture after formation of tris(trimethylsilyl)-phosphine. 

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