Lithium diphenylphosphide

Lithium diphenylphosphide [4S41 -02-2] and related oiganophosphides are chemiluminescent in reaction with oxygen (127). Chemiluminescence is... 

The present procedure illustrates the facile demethylation of methyl aryl ethers by lithium diphenylphosphide.3 This reaction is specific for methyl ethers and may be carried out in the presence of ethyl ethers in high yield.4 Use of excess reagent allows cleavage in the presence of enolizable ketones.5 In the present case, the cleavage may be performed without protection of the aldehyde, but two equivalents of reagent are required, and the yield is reduced to ca. 60%. 

The exact time and temperature required for complete reaction must be determined for each individual compound. It has been observed that nucleophilic demethylation of methyl o-alkoxyaryl ethers is accelerated relative to anisole [Benzene, methoxy-],6 and this reaction is no exception. Lithium diphenylphosphide cleavage of anisole is complete in about 4 hours in refluxing tetrahydrofuran, whereas the present reaction is complete within 2 hours at 25°. 

Amos prepared his polymer-supported reagent in two steps from commercially available polystyrene beads (bromination, then condensation with lithium diphenylphosphide). He found that a useful range of sulphoxides could be reduced effectively, in good yields and in a few hours, to give clean samples of sulphides. 

A solution of the sodium salt of yV-methylaniline in HMPA can be used to cleave the methyl group from aryl methyl ethers ArOMe + PhNMe —> ArO + PhNMca- This reagent also cleaves benzylic groups. In a similar reaction, methyl groups of aryl methyl ethers can be cleaved with lithium diphenylphosphide (PH2PLi). " This reaction is specific for methyl ethers and can be carried out in the presence of ethyl ethers with high selectivity. 

B. From Metallated Phosphines.—Lithium diphenylphosphide and ethylene oxide produce (7), which when added to chlorodibutyl- or chlorodiphenyl-phosphine yields 2-diphenylphosphinoethyl phosphinites (8). 

The ditertiary phosphines (11), prepared from the corresponding alkyl chloride and lithium diphenylphosphide (10), - react with sodium in liquid ammonia to give the phosphines (12). 

Selective demethylation of (63) to the phenolic ether (64) has been achieved by the use of lithium diphenylphosphide. ... 

The only ditelluro-phosphorus acid reported to date is lithium dip-henylditellurophosphinate, [Ph2PTe2] Li+, prepared from the reaction of lithium diphenylphosphide with elemental tellurium (analogous to Equation 30).36,45... 

From MetallatedPhosphines. The synthesis of polymeric tertiary phosphines based on the reaction of lithium diphenylphosphide with chloromethylated polystyrenes continues to attract interest.9 10 Considerable breakdown of the carbon-carbon back-bone of PVC occurs on reaction with lithium diphenylphosphide in THF, and only oligomers of low molecular weight result.11 The potassium salt (9) reacts with chloromethylated polystyrene to form the polymeric diphosphine (10).12... 

Similarly, the chloroalkylarsine (15) (obtained from lithium diphenylarsenide and 1,2-dichloroethane) reacts with lithium diphenylphosphide to form the mixed phosphine-arsine (16).14... 

The product of the reaction between lithium diphenylphosphide (or trimethyl-silyldiphenylphosphine) and dimethyl 2,3-dichloromaleate has been shown to be the fumarate (17)17 and not (as previously supposed)18 the expected maleate (18). 

Triarylphosphines were prepared by the reaction between lithium diphenylphosphide in THF and m-and p-iodotoluene (or the corresponding bromo compounds), 4-bromobiphenyl and p-dibromobenzene in yields of 70-80% (isolated after oxidation, as the phosphine oxides).143 The absence of cine substitution products is a synthetic advantage and would have been taken as a prima facie indication that the displacements are examples of the 5rn1 reaction, had the mechanism been recognized at the time. Operation of the radical ion mechanism in DMSO, or liquid ammonia, in which marginally improved yields are obtained, was confirmed by Swartz and Bunnett,48 but no extension to the scope of the reaction was made. Rossi and coworkers have developed a procedure for one-pot preparation of triarylphosphines starting from elemental phosphorus (Scheme 6).146 As an example of the synthesis of a symmetrical tri-arylphosphine, triphenylphosphine (isolated as its oxide) was obtained in 75% yield, with iodobenzene as the aryl halide (ArX in Scheme 6, steps i-iii only). Unsymmetrical phosphines result from the full sequence of reactions in Scheme 6, and p-anisyldiphenylphosphine (isolated as its oxide) was produced in 55% yield, based on the phosphorus used, when chlorobenzene (ArX) and p-methoxyanisole (AiOC) were used. 

R,R )-4,5-Bis(diphenylphosphinomethyl)-2,2-diphenyl-l,3-dioxolane (Compound 23). A solution of 12.8 mmol of lithium diphenylphosphide in 65 mL of THF was prepared using 2-chloropropane to destroy the phenyllithium. This mixture was stirred for 16 h at 25°C with the above bis-tosylate. Evaporation of the solvent followed by hydrolysis and extraction gave a product which crystallized from ethanol mp 135-137°C, [a] ° = -40.4°C (1, C6H6). 

Phosphine 12 was prepared by cleaving the methyl ether on DiPAMP with lithium diphenylphosphide in tetrahydrofuran (THF) at ambient temperatures. 

Treating /-butyldiphenyl(phenylepoxy)silane 145 with lithium diphenylphosphide and then with methyl iodide provided (Z)- silyl enol ether 146211 (equation 92). The formation of the Z-isomer suggested an anti arrangement between the phosphonium and silyl groups at the silyl migration step (equation 93). 

This transformation was satisfactorily achieved [27, 28] in the anti cryptophanes 38, 45, and 46 by means of lithium diphenylphosphide to give the corresponding hexaphenols 47-49 in good yields. 

Demethylation of the two methyl ether groups in 106 1 [Scheme 4.108) was difficult because the benzylic alcohols were labile to both acid and base.197 Protracted treatment of 108 1 with excess lithium diphenylphosphide at room temperature eventually gave the bisdemethylated compound 10fL2 in 95% yield. 

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