Triphenyl phosphine, supported

Finally, a reaction should be mentioned in which a nucleophile gives support to another reacting species without appearing in the final product. Diphenyl cyclopropenone interacts with 2,6-dimethyl phenyl isocyanide only in the presence of tri-phenylphosphine with expansion of the three-ring to the imine 344 of cyclobutene-dione-1,2229,230 Addition of the isocyanide is preceded by formation of the ketene phosphorane 343, which can be isolated in pure formss 231 it is decomposed by methanol to triphenyl phosphine and the ester 52. 

In a related study, Srivastava and Collibee employed polymer-supported triphenyl-phosphine in palladium-catalyzed cyanations [142]. Commercially available resin-bound triphenylphosphine was admixed with palladium(II) acetate in N,N-dimethyl-formamide in order to generate the heterogeneous catalytic system. The mixture was stirred for 2 h under nitrogen atmosphere in a sealed microwave reaction vessel, to achieve complete formation of the active palladium-phosphine complex. The septum was then removed and equimolar amounts of zinc(II) cyanide and the requisite aryl halide were added. After purging with nitrogen and resealing, the vessel was transferred to the microwave reactor and irradiated at 140 °C for 30-50 min... 

To introduce the Rh-centre in the supported ionic liquid, a solution of [Rh(CO)2(acac)] in acetonitrile was treated with either the ligand tri(m-sulfonyl)triphenyl phosphine trisodium salt (TPPTS) or the ligand tri(m-sulfonyl)triphenyl phosphine tris(l- butyl-3-methyl-imidazolium) salt (TPPTI) (Rh/P ratio of 1 10). The ligand TPPTI was found to dissolve in [BMIM][BF4] and... 

Catalytic forms of copper, mercury and silver acetylides, supported on alumina, carbon or silica and used for polymerisation of alkanes, are relatively stable [3], In contact with acetylene, silver and mercury salts will also give explosive acetylides, the mercury derivatives being complex [4], Many of the metal acetylides react violently with oxidants. Impact sensitivities of the dry copper derivatives of acetylene, buten-3-yne and l,3-hexadien-5-yne were determined as 2.4, 2.4 and 4.0 kg m, respectively. The copper derivative of a polyacetylene mixture generated by low-temperature polymerisation of acetylene detonated under 1.2 kg m impact. Sensitivities were much lower for the moist compounds [5], Explosive copper and silver derivatives give non-explosive complexes with trimethyl-, tributyl- or triphenyl-phosphine [6], Formation of silver acetylide on silver-containing solders needs higher acetylene and ammonia concentrations than for formation of copper acetylide. Acetylides are always formed on brass and copper or on silver-containing solders in an atmosphere of acetylene derived from calcium carbide (and which contains traces of phosphine). Silver acetylide is a more efficient explosion initiator than copper acetylide [7],... 

The preparation of polymer-supported iridium catalysts (61) and (62) for the stereoselective isomerization of double bonds using polystyrene based immobilized triphenyl phosphine were recently reported by Ley and coworkers (Fig. 4.5). The immobilized catalyst is potentially useful for deprotection strategies of aUyl ethers [130]. 

An ionic liquid was fully immobilized, rather than merely supported, on the surface of silica through a multiple-step synthesis as shown in Fig. 15 (97). A ligand tri(m-sulfonyl)triphenyl phosphine tris(l-butyl-3-methyl-imidazolium) salt (tppti) was prepared so that the catalyst, formed from dicarbonylacetylacetonate rhodium and the ligand (P/Rh = 10), could be soluble in both [BMIMJBFq and [BMIM]PF6. The supported ionic liquid-catalyst systems showed nearly three times higher rate of reaction (rate constant = 65 min ) that a biphasic system for the hydroformylation of 1-hexene at 100°C and 1500 psi in a batch reactor, but the n/i selectivity was nearly constant the same for the two ( 2.4). Unfortunately, both the supported and the biphasic ionic liquid systems exhibited similar metal leaching behavior. 

Supported carbodiimides can be produced via aza-Wittig reactions. The example in Scheme 11 shows the reaction of a benzylic azide with triphenyl-phosphine to give an aminophosphorane.31 This was then coupled with phenylisothiocyanate to give the corresponding carbodiimide. 

In the last few years numerous reports have been published in the field of microwave-promoted aryl halide cyanation, utilizing nickel [71], palladium [72,73] and copper [74,75] catalysis. Even water [75] and ionic liquids [76] have proven useful as solvents in these processes. Srivastava and Collibee have exemplified a swift and dynamic procedure using polymer-supported triphenyl phosphine to enable easy subsequent removal through filtration [72]. As shown in Scheme 19, both bromides and iodides could be activated using palladium catalysis in DMF. Even without optimization of the individual reaction times, the overall process time involving simple filtration and extraction for compound isolation appears to be short. 

The active metal complex could be quantitatively stripped from the silica support material by washing with methanol, and consequently, the receptor (the silica support) could be used in several, different reaction cycles. The rhodium catalyst was reused in 11 consecutive runs in batch mode for the hydroformylation of oct-l-ene (80 °C, 20-50 bar) there was no noticeable loss of activity (<0.1% per run) when a xantphos derivative was used as a ligand, and there was an approximate loss of 1% per run when a triphenyl-phosphine-derived monodentate ligand was used (Figure 32). Turnover... 

The hydroformylation of 1-hexene by supported ionic liquid catalysis (SILC) was recently reported by researchers at ExxonMobil. In this system, the active catalyst HRh(CO)(tppti)3 (tppti = tri(m-sulfonyl)triphenyl phosphine tris(l-butyl-3-methyl-imidazolium)) is contained within the ionic liquid phase while excess tppti ligand is immobilized in the support material. TOP values of 65 min" were obtained with silc while an unsupported biphasic ionic liquid medium gave TOP values of 23 min. ... 

To solve the problem of metal recycle, one idea was to fix the rhodium on an inactive support. This rhodium was then extracted from the support by a triphenyl-phosphine-containing solution, thus producing in situ the homogeneous homophase catalyst solution. Friedrich et al. [46] described such a process of rhodium-catalyzed hydroformylation including filtration of the supported catalyst, cooking of the support in a rotary furnace, and thermal stressing distillation of the filtrate, thus separating Rh from the products. 

Procedure [82,83]. 9-Phenylfluoren-9-yl-PS (PhFl) modified amino-methylpolystyrene li was suspended in DMF and treated with 4-bromoben-zoic acid (10 equiv.) and A-methylmorpholine (10 equiv.) at 80°C for 4 days. The reaction mixture was quenched by addition of MeOH and the resin was then washed with DMF, MeOH, and CH2CI2. To the resin-bound bromide in 1,2-dimethoxyethane (DME) was added phenylboronic acid (2 equiv.), NajCOs (2.5 equiv. from a 2 M aqueous solution), and tetrakis(triphenyl-phosphine)palladium (0.005 equiv.). The mixture was heated at 80°C for 16 h and then washed successively with DME-H2O, sodium diethyldithiocar-bamate-DIEA in DMF (20 mmol), DMF, MeOH, and CH2CI2. 4-Phenyl-benzoic acid was cleaved from the support by treatment with 20% TFA in CH2Cl2-MeOH (9 1) for 2 h. The product was isolated in 67% yield after chromatography on kieselgel. 

A device which has been frequently used to produce a starting material with just one acyl group in place is to carry out a Beckmann rearrangement on an ortho-hydroxyaryl ketone, the Beckmann product cyclising in situ when the conditions are acidic a modern version of this is illustrated below." " An excellent route to mono-acylated precursors utilises mixed anhydrides.A very mild method for the dehydrative ring closure of or /io-hydroxyarylamino amides, employed in solid-supported benzoxazole syntheses, utilises typical Mitsunobu conditions - triphenyl-phosphine and diethyl azodicarboxylate." ... 

Scheme 1S.S3. Aryl cyanation using palladium and polymer-supported triphenyl phosphine.

A group at Exxon immobilized an ionic liquid phase ([BMIM][PFg]) onto modified silica gel (Figure 7.18) [108]. The ionic liquid phase hosted the catalyst HRh(CO)(tppti)3 (tppti = tri(m-sulfonyl)triphenyl phosphine tris(l-butyl-3-methyl-imidazohum)) as well as the excess of noncoordinated ligand. In the hydroformylation of 1-octene, lower activities of the biphasic system in comparison to the simple supported IL system were noted. This was explained by a higher concentration of the active rhodium species at the interface and the... 

Figure 7.18 Supported ionic liquid catalysis applied in the hydroformylation of 1-hexene (tppti = tri(m-sulfonyl)triphenyl phosphine tris(1-butyl-3-methyl-imidazolium) salt. (Taken and modified from Ref. [108].)...

Polystyrene-supported Au catalysts 17 and 18 have been prepared using the route outlined in Scheme 40. Polystyrene bound triphenyl phosphine was treated with [(Me2S)Au]Cl in dichloromethane at room temperature for 6h to obtain 16. Two different heterogeneously supported Au catalysts, 17 and 18 were obtained by simple ion exchange reaction of AgOTf and AgNTf2 wifh 16. These two catalysts were used to provide the furan derivative by the intramolecular 5-endo-dig cycloisomerization of alkynyl-diol (Scheme 41) [63]. 

Alternatively, alkyl aryl ethers can be prepared from support-bound aliphatic alcohols by Mitsunobu etherification with phenols (Table 7.13). In this variant of the Mit-sunobu reaction, the presence of residual methanol or ethanol is less critical than in the etherification of support-bound phenols, because no dialkyl ethers can be generated by the Mitsunobu reaction. For this reason, good results will also be obtained if the reaction mixture is allowed to warm upon mixing DEAD and the phosphine. Both triphenyl- and tributylphosphine can be used as the phosphine component. Tributyl-phosphine is a liquid and generally does not give rise to insoluble precipitates. This reagent must, however, be handled with care because it readily ignites in air when absorbed on paper. 

Thermolysis of ()) -cyclopentadienyl)bis(neopentyl)(tri-methylphosphine)vanadium(I) (82) in the presence of 1,2-bis(dimethylphosphuio)ethane leads to the formation of the Schrock-type see Schrock-type Carbene Complexes) alkylidene vanadium complex (83), which is supported by X-ray crystallographic analysis (Scheme 45). " The imido vanadium complex (84) is converted to the corresponding alkylidene complex (86) on treatment with ben-zylidene(triphenyl)phosphorane (85) via substitution of the phosphine ligand (Scheme 46). ... 

Under standard MTO-catalyzed oxidation conditions with hydrogen peroxide, tertiary phosphines, triphenylarsine, and triphenyl-stibene were all efficiently oxidized. A detailed account of the rates of reactions of these oxidative processes has been reported which supports a mechanism that allows for nucleophilic attack of the substrate at the rhenium peroxide species. ... 

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