By triphenylphosphine

Thiirane 1,1-dioxides extrude sulfur dioxide readily (70S393) at temperatures usually in the range 50-100 °C, although some, such as c/s-2,3-diphenylthiirane 1,1-dioxide or 2-p-nitrophenylthiirane 1,1-dioxide, lose sulfur dioxide at room temperature. The extrusion is usually stereospeciflc (Scheme 10) and a concerted, non-linear chelotropic expulsion of sulfur dioxide or a singlet diradical mechanism in which loss of sulfur dioxide occurs faster than bond rotation may be involved. The latter mechanism is likely for episulfones with substituents which can stabilize the intermediate diradical. The Ramberg-Backlund reaction (B-77MI50600) in which a-halosulfones are converted to alkenes in the presence of base, involves formation of an episulfone from which sulfur dioxide is removed either thermally or by base (Scheme 11). A similar conversion of a,a -dihalosulfones to alkenes is effected by triphenylphosphine. Thermolysis of a-thiolactone (5) results in loss of carbon monoxide rather than sulfur (Scheme 12). 

Phosphorus ylides are prepared from alkyl halides by a two-step sequence. The first step is a nucleophilic substitution of the Sn2 type by triphenylphosphine on an alkyl halide to give an alkyltriphenylphosphonium salt ... 

I. Halides from Alcohols by Triphenylphosphine-Carbon Tetrahalide... 

II. Halides from Alcohols and Phenols by Triphenylphosphine Dihalide... 

The 1,1-dimetallic compounds, R2C(SnMe3)ZnBr, were oxidized by dry air at —10 to 0°C in the presence of Me3SiCl to give aldehydes or ketones, R2C=0. In a related indirect method, arylthallium bis(trifluoroacetates) (prepared by 12-21) can be converted to phenols by treatment with lead tetraacetate followed by triphenylphosphine, and then dilute NaOH. Diarylthallium trifluoroacetates undergo the same reaction. ... 

It is possible to replace one isocyanide by triphenylphosphine, or to replace two isocyanides with diphos, giving phosphine analogues of these complexes. These species are not available from analogous reactions of phosphine-palladium(O) and (II) complexes. Reactions with active alkyl halides proceeds with oxidation nitric oxide also oxidizes these complexes. [Eqs. (31, 32)]. 

The spreading of Auss clusters capped by triphenylphosphine has been described... 

The deoxygenation of peroxycarbonates (53) with phosphines and phosphites has been examined. Reaction with phosphites favours pyrocarbonate formation (Path A) whilst phosphines favour carbonate formation (Path B). Secondary phosphine oxides are oxidized to phosphinic acids by perbenzoic acid. The kinetics of the deoxygenation of hydroperoxides by triphenylphosphine have been examined and the reaction shown to be catalysed by strong acids. ... 

The mechanism for the Mori-Ban indole formation is representative of many Pd-catalyzed pyrrole annulation processes [123], Reduction of Pd(OAc)2 by PPh3 generates Pd(0) species accompanied by triphenylphosphine oxide and acetic anhydride. 

The only substitution in a tetranuclear cluster which has been studied kinetically is the progressive substitution in Ir4(CO)i2 by triphenylphosphine, and these results have not yet been published in full. The reported experimental data are the follow-... 

Acyl-nitroso-compounds are deoxygenated by triphenylphosphine to give isocyanates, and reaction via the zwitterion (46) was postulated.54... 

Another synthesis of olefins has been described in which the desulphurization of thiirans by triphenylphosphine is featured.72 There have been many reports of the synthesis of compounds of the type (63). These form charge-transfer complexes with acceptors such as tetracyanoquinodimethane which have metallic properties. The... 

The favorable performance of polar solvents is associated with the concentration of the active species. At least five species (5-9) are generated in the mixture upon treatment of RhCl(PPh3)3 with the five-membered hydrogen phosphonate 4a (Scheme 23). Species 8 and 9, which are not ligated by triphenylphosphine, have proved to be inactive, while 5-7 are all able to catalyze the reaction. 

Alkylation of oxime anions followed by hydrolysis is another efficient approach toward 0-alkylhydroxylamines. O-Alkylation of oximes of type 24 (equation 15) can also be done through Michael addition with Bayhs-HiUman adducts of type 23 catalyzed by triphenylphosphine . 

Similarly the cation (18a), which does not react with alkoxides [75JCS(P1)1260], is protodebrominated by triphenylphosphine, albeit a higher boiling solvent, pentan-l-ol, is required to promote the reaction. The salt (18c), which cannot form a dihydrodiazepine base, also undergoes protodebromination when heated with triphenylphosphine in pentan-l-ol [81AG193, 81AG(E)190]. 

A 1 1 adduct formed by triphenylphosphine and bromine converts alcohols to bromides.15 16 17 The alcohol displaces bromide ion from the pentavalent adduct, giving an alkoxyphosphonium intermediate. The phosphonium ion intermediate then undergoes nucleophilic attack by bromide ion, displacing triphenylphosphine oxide. 

Hydroperoxy compounds 29 and 30 are reduced in high yields to their hydroxy analogs by triphenylphosphine. ... 

Hydroperoxide 172 is reduced to 173 by triphenylphosphine. 2,5-Di-tert-butyl-l,3-benzoquinone is isomerized to 174 by boiling with 43 in methylbenzene isomerizations of this type normally must be induced pho-... 

The displacement of the chlorine atom in 395 by triphenylphosphine or other phosphorus derivatives leads to the corresponding phosphorylated oxazolones 397 or 398 that have been used to prepare new and interesting substituted vinylphos-phonium salts (Scheme 7.127). Of particular interest is the synthesis of N-acyl-a-(triphenylphosphonio)glycinates as new cationic glycine equivalents. ... 

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