Methyltriphenylphosphonium bromide

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. 

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

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... 

A solution of 16.2 g methyltriphenylphosphonium bromide in 200 mL anhydrous THF was placed under a He atmosphere, well stirred, and cooled to 0 °C with an external ice water bath. There was then added 30 mL of 1.6 N butyllithium in hexane which resulted in the generation of a clear yellow solution. The reaction mixture was brought up to room temperature, and 7.0 g 3,4-diethoxy-5-(methylthio)benzaldehyde in 50 mL THF was added dropwise, dispelling the color, and the mixture was held at reflux on the steam bath for 1 h. The reaction was quenched in 800 mL HzO, the top hexane layer separated, and the aqueous phase extracted with 2x75 mL of petroleum ether. The organic fractions were combined and the solvents removed under vacuum to give 12.0 g of the crude 3,4-diethoxy-5-methylthiostyrene as a pale amber-colored oil. 

The use of methyltriphenylphosphonium bromide and MeSOCH2 on 5-bromo-2-thienyl-thiophene-2-carbaldehyde (128) furnished the corresponding olefin 133. The reaction with propyne in this case furnished a natural bithiophene 134 isolated from Tagetes minuta (86G747). 

Semicarbazide hydrochloride Phosphorous oxychloride Methyltriphenylphosphonium bromide Butyl lithium... 

To a slurry of 11.7 g (0.33 mole) of methyltriphenylphosphonium bromide in 150 ml of dry tetrahydrofuran at -35°C was added, over a 15-minute period, 20 ml (0.033 mole) of n-butyl lithium. The reaction mixture was stirred for one hour. To the reaction mixture at -35° to -40°C was added over a 10-minute period a solution of 5.7 g (0.0165 mole) of 3-chloro-5,6-bis(4-methoxyphenyl)-l,2,4-triazine in 50 ml of tetrahydrofuran. The reaction mixture was allowed to warm to ambient temperature and was stirred overnight. A solution of 1.05 g (0.0165 mole) of sodium carbonate in 50 ml of water was added dropwise to the reaction mixture which then was heated at reflux for three hours. The reaction mixture was cooled, poured over ice, and extracted with diethyl ether. The diethyl ether extract was washed with water, dried over anhydrous sodium sulfate, and concentrated. The concentrate was chromatographed over silica gel, with three fractions being collected. After evaporation of solvent, the third fraction solidified MP about 109°-113°C. 

To a suspension of methyltriphenylphosphonium bromide (0.196 g, 0.55 mmol) in 1 mL of benzene under argon at room temperature was added a 0.5 M solution of potassium hexamethyldisilazide in toluene (1.2 mL, 0.6 mmol), and the yellow solution was stirred for 5 min. A solution of keto-ester (1) (0.1 g, 0.274 mmol) in 1.5 mL of benzene was added and the orange solution was stirred for 3 h at room temperature. The reaction mixture was filtered through a plug of silica gel with 40% ethyl acetate/hexane. The filtrate was concentrated to afford a solid. Flash chromatography (30% 40% dichloromethane/hexane) yielded the desired product (3) as a white solid (0.077 g, 78%) m.p. 167°-168°C Rf 0.4 (50% dichloromethane/hexane). The structure of the product was also confirmed using IR, iH NMR and mass spectroscopy. 

In 100 ml of tetrahydrofuran is suspended 25 g of methyltriphenylphosphonium bromide and 40 ml of 1.6 N n-butyl lithium hexane solution is dropwise added thereto under a nitrogen atmosphere and ice-cooling. After stirring the mixture under ice-cooling for 30 minutes, a solution obtained by dissolving equal molar quantity of ll-oxo-6,11-dihydrodibenz[b,e]oxepin-2-acetic acid in 250 ml of tetrahydrofuran is dropwise added thereto and the mixture is stirred at room temperature for two hours. The solvent is distilled away under reduced pressure and the residue is purified by column chromatography on silica gel (eluent hexane ethyl acetate = 3 1) to obtain the desired product as a colorless oily... 

Either neat, if in stock, or freshly prepared from instant ylide (Aldrich or Merck) or by reaction of methyltriphenylphosphonium bromide (7.8 g, 22 mmol) and sodium bis(trimethylsilyl)amide (3.6 g, 20 mmol) in tetrahydrofuran (20 mL) at ambient temperature for 1 h.19 cTetrahydrofuran is distilled from sodium benzophenone ketyl under nitrogen. 

AWittig reaction was used to obtain 2-vinyl indoles 1291 (Equation 285) <2002S1810>. The ylide was generated from methyltriphenylphosphonium bromide in anhydrous THE under argon using KHMDS in toluene at room temperature for 0.5 h and then was cannulated to a solution of aldehyde 1290. These conditions were essential to obtain high yields. 

Taylor and Martin (1019, 1020) have described a new procedure for the direct introduction of alkenyl substituents into the pyrazine nucleus 2-chloropyrazine (63) with methylenetriphenylphosphorane (a Wittig reagent) (64, R = H) (from methyltriphenylphosphonium bromide and butyllithium) in 1,2-dimethoxyethane and subsequent treatment with benzaldehyde gave 2-styrylpyrazine (67, R = H). A similar reaction with propionaldehyde gave 2-(but-l -enyl)pyrazine (1020). 

Methylenetriphenylphosphorane, (CeH5)3P=CH2 (in ether solution). Wittig and SchoellkopP describe the preparation of the reagent and its condensation with cyclohexanone as follows. A solution of 0.1 mole of n-butyllithium in about 100 ml. of ether and 200 ml. of additional ether is stirred under nitrogen, and 0.1 mole of crystalline methyltriphenylphosphonium bromide is added continuously over a 5-minute period (evolution of butane causes frothing). Stirring for 4 hrs. at room... 

Methyl triisopropyl acetate, 925 Methyl 3,4,5-trimethoxybenzoate, 163 Methyltriphenylphosphonium bromide, 678, 697, 1245... 

The reaction of triphenylphosphine with bromomethyltriphenylphosphonium bromide in refluxing ethanol led, unexpectedly, to methyltriphenylphosphonium bromide in high yield. ... 

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