Silylphosphines

Lithium aluminium hydride has been used to cleave a furfuryl group from a range of furfurylphosphonium salts, which are easily accessible by the reactions of trimethylsilylphosphines with furfuryl bromide. Thus, e.g., the reaction of diphenyltrimethyl-silylphosphine yields the salt (52) which, on treatment with... 

The thermolysis of a linear (fluorostannyl)silylphosphine has been reported to give the corresponding stannaphosphene.8 This reaction can be considered to be a defluorosilylation and, as such, is analogous to the dehydrohalogenation reactions discussed below. 

Silylphosphines add thermally to the carbon-carbon triple bond of acetylenic ketones. The reaction affords (Z)-a-silyl-/Tphosphino-a,/3-unsaturated ketones via regioselective cis- 1,2-addition (Equation (124)).286... 

Dialkyl(trimethylsilyl)phosphines undergo 1,4-addition to a,/3-unsaturated ketones and esters to give phosphine-substituted silyl enol ethers and silyl ketene acetals, respectively. A three-component coupling reaction of a silylphosphine, activated alkenes, and aldehydes in the presence of a catalytic amount of GsF affords an aldol product (Scheme 76).290 291... 

Silylphosphines are known to add to aldehydic carbonyl groups.292 The reaction between Me3Si-PPh2 and chiral aldehydes proceeds with a high diastereoselectivity to afford ct-siloxyalkylphosphines (Equation (125)).293... 

Addition reactions of silylphosphines to imines have been reported, 4 as illustrated for diethyl(trimethylsilyl)phosphine (70). Organic azides react with germylphosphines by an insertion pathway,65 as shown for various phenyl(trimethylgermyl)phosphines (71). The initial products (72) isomerize to phosphine imines on heating.66... 

With SiHsI phosphine probably forms silylphosphine and with (CH3)2BBr, crystalline H2PB(CH3>2 Germanium halides do not react with phosphine... 

With ethyl iodide, ethylphosphine and phosphine are formed. The reaction with excess silyl bromide results in the formation of silylphosphine. Silylphosphine, like methylphosphine, forms an adduct with diborane... 

The most direct synthesis is performed by reaction of a dihalo compound with a tricoordinated phosphorus compound including a reactive P—Y bond (reaction 101). This synthesis, first used with secondary phosphines, the corresponding phosphides or diphosphines (Y = H, Na, K, PPh2)2b,38°, has subsequently been developed also with silylphosphines (Y = SiMe3),132,381-383 which are easier to handle (reaction 102). The same kind of cyclization by intramolecular alkylation can be achieved using a functional phosphine prepared in a multi-step synthesis380,384,385 (reaction 103). 

Synthesis of multiply bonded phosphorus compounds using silylphosphines and silylphosphides... 

II. SURVEY OF SILYLPHOSPHINES AND ALKALI METAL SILYLPHOSPHIDES A. Trisilylphosphines... 

Tri-t-butylphenyl)(trimethylsilyl)phosphine (10a) and its t-butyldimethylsilyl analog (10b) were prepared from (2,4,6-tri-t-butylphenyl)phosphine33 (equation 76)3. Treatment of the silylphosphines 10a or 10b with n-butyllithium led to the formation of silylphosphides 11a and lib3, which were utilized for the reactions shown in Section V. (2,4,6-Tri-r-butylphenyl)(triphenylsilyl)phosphine and related compounds were also prepared starting from Mes PH i (equation 77) and their structures were analyzed27,89. 

Reaction of 10a with Mes P=C=0 afforded the adduct 12 (equation 78)90. It should be noted that compounds of the Mes P=C(OSiR3)PHMes type were converted to Mes P=C=PMes by addition of alkyllithiums90,91. Isophosphaethyne complexes were prepared using 10a as well as the related silylphosphines (equation 79)92. Stable cis-diphosphene was prepared from 10a and a dichloroaminophosphine, and its structure was analyzed by X-ray crystallography (equation 80)93. 

Mass Spectra of Volatile Hydrides. III. Silylphosphine. Inorg. 

Mit SiH3J bildet Phosphin vermutlich Silylphosphine 288>, mit (CHa)2BBr kristallines H2PB(013)2 289>. Die Germaniumhalogenide reagieren nicht mit Phosphin 299>. 

Caution. The silylphosphines and many of the intermediates described in the following preparations are very sensitive to oxygen and moisture. All of the phosphines are extremely toxic, and the alkyl phosphines are spontaneously flammable in air. All operations involving these materials should be carried out in an inert atmosphere and in a good hood. 

Di(silyl)benzene gives the di(chlorosilyl)benzene reagent upon treatment with boron trichloride (Scheme 3). Contrary to the parent compound, this derivative is readily solvolyzed and gives cyclic siloxanes, silthianes, silazanes and silylphosphines on contact with water, hydrogensulfide, ammonia, amines, or phosphines, respectively. 

Silylphosphines, (R3Si)3P, are well known. On the basis of electronegativity (Table 1) they are weaker n acids than organophosphines. With the isolation of R2Si=PR compounds, an increased variety of structmes is available. Six-membered silicon-phosphorus heterocycles (1) have been proposed as ligands for catalyst candidates, owing to the steric accessibility of the transition metal. 

Si-H containing silylphosphines, however, leads to cleavage of an Si-P bond and alkylation at silicon. These reactions, and many other interesting cyclic and acyclic phosphines, most of which contain alkyl groups on sihcon, are discussed in more detail by Fritz. ... 

MeSiH2)PH + PHj Lithiated silylphosphine equilibrates with LiPH2 and (SiHj)2PLi ... 

The (GeHj), being unstable, decomposes to (GeH), GeH, traces of higher ger-manes and Hj. Silylphosphine or SijHjPHj react below —78°C when coordinated to BFj. Phosphine is produced quantitatively. 

From primary or secondary silylphosphine deuterolysis, mixed hydro-deuterio products form ... 

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