Methyltriphenylphosphonium iodide

Method a. (ji-Styryl) phenyl telluride. To a solution of methyltriphenylphosphonium iodide (0.405 g, 1 mmol) in dry THF (4 mL) at room temperature was added dropwise n-BuLi (2 mmol). After stirring at room temperature for 20 min the solution was cooled to -78°C and a solution of PhTeBr (0.28 g, 1 mmol in 2 mL THF) was added, followed by benzaldehyde (0.16 g, 1.5 mmol). The temperature was raised to room temperature and stirred for 3 h. The solvent was removed under vacuum and the residue incorporated on Si02 and purified by flash column chromatography (Si02/hexane) giving an oil. Yield 0.185 g (60%). E/Z=2. 

Furthermore, phosphonium salts have been applied as catalysts in the TMSCN addition to aldehydes [118] and ketones [119]. Methyltriphenylphosphonium iodide [118] was fonnd to be a reasonably active catalyst for the addition of TMSCN to aldehydes at room temperatnre by the gronp of Plumet. In general, the yields varied between 70% and 97% in 24 h, depending on the aldehyde, applied in the reaction (Scheme 46). However, the salt did not support the addition of TMSCN to ketones, with one exception, when the highly reactive cyclobutanone was applied in the reaction [120]. 

NaH (1.55 g, 0.032 mol, 50% oil dispersion) was placed in a three-necked flask under argon. The NaH was washed several times with pentane by decantation. The flask was then fitted with a condenser, a drying tube and a dropping funnel equipped with an argon inlet tube. Anhyd DMSO (17 mL) was added dropwise, and then the mixture was heated at a bath temperature of 75 °C for 1 h. The mixture was cooled in ice, and a solution of methyltriphenylphosphonium iodide (13.3 g, 0.033 mol) in warm DMSO (30 mL) was added dropwise. The solution was then stirred at 25 C for 15 min and cyclobutanonc (2.25 g, 0 032 mol) in DMSO (5 mL) was added dropw ise. After stirring the mixture for 1 h. bulb-to-bulb distillation at 20 Torr was carried out while the bath temperature was maintained at < 75 C the distillate was collected in a dry ice cooled receiver yield 1.94g (90%). 

Methyltriphenylphosphonium iodide was prepared by the following procedure. Triphenyl phosphine was recrystallized from ethanol and dried over phosphorus pentoxide under reduced pressure for 12 hr. A solution of 39 g (0.15 mol) of triphenylphosphine and 10.0 roL (22.8 g, 0.16 mol) of iodomethane in 105 mL of benzene was allowed to stir at room temperature for 12 hr. The precipitate was filtered, washed with benzene, and dried over phosphorus pentoxide under reduced pressure for 12 hr. The yield was 57 g (94%), mp 189°C (lit. mp, 182°C). The reagent is also available from Aldrich Chemical Company, Inc. 

The submitter states that the slight excesses of phenyllithium (5 ) and methyltriphenylphosphonium iodide (10%) specified ensure complete corversion of the aldehyde and simplify the purification of the product since the excess phosphonium salt is readily removed during filtration through Florosil. 

The enthalpies of solution and apparent molar volumes in various solvents have been determined for methyltriphenylphosphonium iodide (10) rate constants, activation enthalpies, activation volumes and reaction enthalpies were also determined for its synthesis from triphenylphosphine and methyl iodide156. (Equation 3). 

Reductive coupling of allylic halides. This cobalt complex (1 equiv.) effects reductive coupling of allylic halides to form 1,5-dienes with preservation of the geometry of the double bonds/ The major product from coupling of terpenoid allylic halides is that formed by head-to-head coupling. The triphenylphosphine liberated during the reaction is removed as methyltriphenylphosphonium iodide, obtained by reaction with methyl... 

Another homologation reaction extensively studied with bimetallic catalysts is the conversion of methyl acetate into ethyl acetate. The most active and also most selective system is composed of Ru3(CO)12 and Co2(CO)g (1 9) in acetic acid with lithium acetate-methyltriphenylphosphonium iodide promoters yields of 71% product with a catalytic turnover of 2505 in less than 1 hr are reported (260). 

Method a. (fl-Styryl) phenyl telluride. To a solution of methyltriphenylphosphonium iodide (0.405 g, 1 mmol) in dry THF (4 mL) at room temperature was added dropwise n-BuLi (2 mmol). After stirring at room temperature for 20 min the solution was cooled to... 

Methyltriphenylphosphonium iodide, (CH3)(C6H5)3PI.—Triphenylphosphine combines violently with methyl iodide to yield the phosphonium iodide, which consists of shining plates, M.pt. 165° to 166° C. The corresponding chloride crystallises with one molecule of water, which is ehminated at 100° to 110° C., the anhydrous compound melting at 212° to 213° C. its platinichloride forms orange needles, M.pt. 287° to 238° C. 

An aqueous solution of methyltriphenylphosphonium iodide or chloride is treated with freshly precipitated silver oxide and boiled with water until a filtered test portion of the solution shows no turbidity with silver nitrate. The mixture is then entirely filtered and the filtrate evaporated to dryness on the water-bath. The residue is extracted with ether, the solvent removed and the product crystallised from ether, prisms resulting, M.pt. 110° to 111° C. The oxide has also been prepared by the interaction of diphenylchlorophosphine and sodium methoxide, when it melts at 109° to 110° C., methyldiphenylphosphine occurring as a by-product. When obtained by heating an alcohol solution of methyltribiphenylphosphonium iodide with moist silver oxide, it crystallises in needles, M.pt. 223° to 224<° C. ... 

Carbonyl methylenation with methylentriphenylphosphorane, generated in situ from methyltriphenylphosphonium iodide in dimethylsulfoxide at 70 °C, introduces the exocyclic double bond. The resulting alkene 3 is protonated with /7-toluene-sulfonic acid in refluxing benzene solution to the intermediate carbenium ion 2. This undergoes a ring-expanding 1,2-alkyl shift to the carbenium ion 1, which deprotonates to racemic isocomene, as expected. 

From methyltriphenylphosphonium iodide, prepared by methylation of triphenylphosphine with highly tritiated methyl iodide, the enhanced, coupled % NMR spectrum shows fully resolved and interleaved, doublet, triplet, and quartet signals from the PCT3,... 

Figure 12. Resolution-enhanced % NMR spectrum of [methyl- H]methyltriphenylphosphonium iodide in DMSO-d at 96 MHz.

Methyltriphenylphosphonium iodide, 187-88 MINDO calculations, 37,39-40 Molecular complexes, 369 Molecular mobility, 363-64 also see Dynamic processes and Rotation Molybdate ions, 0 chemical shifts, 255-56 Molybdenum chemical shifts, 449-50 Molybdenum-95,97 NMR, 7,9,10,12-13,446,449-50 Moments, spectral, 114,161-62 Monte Carlo technique, 272,279 Motional averaging, 117,119-20 MREV, 122... 

J.P.H. Verheyden and J.G. Moffatt, Halo sugar nucleosides. 1. lodination of the primary hydro) l groups of nucleosides with methyltriphenylphosphonium iodide. /. Org. Chem. 35 2319 (1970). 

C]Methyltriphenylphosphonium iodide has emerged as a labeling reagent of importance comparable with " CH3Mgl. It is conveniently prepared from [ C] methyl iodide and triphenylphosphine in nearly quantitative yield (Figure 5.64). Its ylide, which is... 

Triphenylphosphinehydrocinnamoylmethoxycarbonylmethylmethylene refluxed 40 hrs. in benzene in the presence of benzoic acid, methyl iodide added, refluxing continued 2 hrs., and the resulting methyltriphenylphosphonium iodide removed by filtration methyl 3-hydrocinnamoylacrylate. Y 80%. F. e. s. H.-J. Bestmann, G. Graf, and H. Hartung, A. 706, 68 (1967). 

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