Methyltriphenylphosphonium

In the absence of the carbonyl or similar stabilizing group, the onium salts are much less acidic. The pATp so of methyltriphenylphosphonium ion is estimated to be 22. Strong bases such as amide ion or the anion of DMSO are required to deprotonate alkylphos-phbnium salts ... 

Methoxytrimethylsilane, 123 Methyl acetoacetate, 92 Methyl bromoacetate, 107 Methyl 11-hydroxyundecanoate, 58 Methyl lithium, 27,28 Methyl 10-undecenoate, 58 2-Methyl-l, 3-dithiane, 81 (fl/ ,5 )-Methyl-3-phenyldiniethyl-silyl-3-phenylpropionic acid, 53-4 2-Methyl-3-Phenylprop-2-cnal, 111 2-Methyl 2-lrimethylsilyl-1,3-dithiane, 81 2-Methyl-l-(trimcthylsilyloxy)cyclo-hex-l-ene, 100,109 2-Melhyl-l-lrimethylsilyloxy)cyclo-hcx-6-enc, 100 2-Methyl-2-trimethylsilyloxy-pentan-3-one, 132 2-Methylacetophenone, 42-3 2-Methylbutyraldehyde, 85 2-Methylcyclohexanone, 99,100 2-Methylcyclohexanone, 131 4-Methyldec-4-ene, 67-8 Methylenation, 63 2-Methylpropen-l-ol, 131 Methyltriphenylphosphonium bromide, 27 Michael addition, 85 Monohydridosilanes, 128 Monohydroalumination, 29... 

Methyl-2-trimethylsilyloxy-pentan-3-one, 133 2-Methylacetophenone, 42-3 2-MethylbutyraIdehyde, 85 2-Methylcyclohexanone, 99, 100 2-Methylcyclohexanone, 132 4-Methyldec-4-ene, 67-8 Methylenation, 63 2-Methylpropen-l-ol, 132 Methyltriphenylphosphonium bromide, 27 Michael addition, 85 Monohydridosilanes, 128 Monohydroalumination, 29... 

Monomer Synthesis. 4-Allyloxystyrene was prepared by the Wittig reaction of 4-allyloxybenzaldehyde and methyltriphenylphosphonium bromide, under basic conditions. The allyloxybenzaldehyde was prepared, in turn, by the alkylation of 4-hydroxybenzaldehyde with allyl bromide. This method, which provides high purity monomer in high overall yield, is outlined in Scheme 1 and has been previously described (2). Alternatively, the monomer may be prepared by the direct alkylation of p-vinylphenol with allyl bromide (8,9), although this method is less convenient due to the difficulties in synthesizing and storing the highly reactive vinyl phenol (10). 

Direct hydrogenation of key intermediate 248 over the Adams catalyst and subsequent lithium aluminum hydride reduction yielded the two stereoisomeric alcohols 256 and 257, which were separately transformed to ( )-corynantheal (258) and ( )-3-epicorynantheal (259), respectively, by Moffatt oxidation, followed by Wittig reaction with methyltriphenylphosphonium bromide and, finally, by demasking the aldehyde function (151, 152). 

As an alternative process for getting from (III) to (VI), combine 64.2g (0.18M) methyltriphenylphosphonium bromide in dry benzene with 11.6g (0.18M) (in 14% solution) butyllithium in benzene. Heat to 60° C and cool. 49.Og (0.176M) (III) in 40 ml dry benzene is added (keep temperature below 40° C) and then reflux 2 hours. Cool, filter and evaporate in vacuum to get the octene, which after catalytic hydrogenation as described for (V) yields (VI). 5-Alkylresorcinols Aust. J. Chem. 21,2979(1968)... 

Preparation of 4-12-cvclohexenvloxv )-stvrene. A stirred mixture of 34.36g (0.096 mole) methyltriphenylphosphonium bromide and 10.75g (0.096 mole) potassium t-butoxide in 200ml dry THF is treated drop-wise with a solution of 16.16g (0.080 mole) of 4-(2-cyclohexenyl)-benzaldehyde in 30ml THF under inert atmosphere. Once the addition of aldehyde was completed, the mixture was stirred at room temperature for another 2 hours. Ether and water were then added to the reaction mixture until clearly separated phases were obtained with no solid residue. The organic layer was separated and washed three times with water, dried over magnesium sulfate and evaporated. The resulting semi-solid was triturated in 10% ethyl acetate-hexane mixture to remove most of the triphenylphosphine and the evaporated extract was purified by preparative HPLC using hexane as eluent. This afforded 9.35g (58%) of the pure monomer, which was fully characterized by H and C-NMR as well as mass spectrometry. 

Preparation of 3.5-dimethvl-4-f2-cvclohexenvloxvfstvrene. A well stirred mixture of 36.52g (0.102 mole) methyltriphenylphosphonium... 

Direct chlorination of the substrate by the dichlorotriphenylphosphorane present in the reaction mixture competes with the above route. The HC1 liberated is taken up by the dichloromethylenetriphenylphosphorane also present to form dichloro-methyltriphenylphosphonium chloride (78), which reacts further with triphenylphosphine with the eventual formation of chloromethyltriphenylphosphonium... 

The reaction of steviol norketone (28) with [3H]methyltriphenylphosphonium bromide in the presence of potassium t-butoxide (Scheme 7) has been used in the... 

Figure 1 Chemical structures of commonly used typical mitochondriotropic molecules (A) rhodamine 123 (B) methyltriphenylphosphonium (Q dequalinium chloride.

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]. 

Acetyl-3-bromofuran (1141) was prepared by Friedel-Crafts acylation of 3-bromofuran (1140). Wittig reaction of 1141 with methyltriphenylphosphonium bromide and butyllithium led to 3-bromo-2-propenylfuran (1142), which, on Sonogashira coupling with ethyl 2-ethynylphenylcarbamate (1143), provided N-protected (2-isopropenylfur-3-yl)ethynylaniline 1144. The TBAF-promoted... 

Also the preparation of methyltriphenylphosphonium dichromate ((Ph3PMe)2Cr207) and the application of this compound as efficient, inexpensive, stable and mild reagent for coupling a variety of aliphatic and aromatic thiols and aliphatic dithiols to their corresponding acyclic and cyclic disulfides has been published <2006JSF441> 1,2-dithiane was obtained by this procedure in 90% yield. 

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). 

The results of the pulse radiolysis in aqueous solution of substituted phosphonium ions have been investigated38 in addition to those of the electrode reduction of benzyl triphenyl-phosphonium ion39 and quaternary phosphonium salts with hydrated electrons40-42. The radiolysis of methyltriphenylphosphonium, dimethyldiphosphonium and trimethyl-phenylphosphonium ions in neutral aqueous solutions leads to phosphoranyl radicals... 

A three-necked flask, fitted with a dropping funnel, thermocouple lead, and serum stopper, was thoroughly flame-dried and was charged with 2,66 g (7.75 mmol) of methoxy-methyltriphenylphosphonium chloride (recrystallized from ethyl acetate-chloroform and dried at 100°C/1 mm) and 40 mL of anhydrous THE The mixture was cooled to -20°C, and from a dropping funnel 4.75 mL of 1.6M n-butyl lithium in hexane was added. After all the... 

---