Potassium -butoxide triphenylphosphine

B. DicMoromethylenetriphenylphosphorane. In one jiortion 131 g. (0.5 mole) of triphenylphosphine (Note 7) is added to the cooled suspension of potassium /-butoxide in heptane, and to the well-stirred mixture a solution of 59.5 g. (0.5 mole) of chloroform in 500 ml. of dry heptane is added dropwise over a period of... 

Tetrakis(triphenylphosphine)palla-dium(0), 289 Tributyl tin chloride, 315 of amines and other N-alkylations Potassium /-butoxide, 252 of carboxylic acids and acyl derivatives at the a carbon... 

EPOXIDES N-Bromosnccinimide. Di-methylsulfonium methylide. Potassium r-butoxide. Triphenylphosphine-Diethyl azodicarboxylate. 

Homoconjugated or skipped trienes are vital components of natural products such as fatty acids, leucotrienes and insect pheromones. Pohnert and Boland have reported a detailed discussion of the synthesis of these molecules using a one-pot Wittig approach which employs bis(ylides) (77), (78) and (79) as key building blocks.New one-pot Wittig procedures have also been developed for the synthesis of alkynes and bromoalkynes (Scheme 13) and iodoalkynes (Scheme 14). The latter process utilises diiodomethyltriphenyl-phosphorane (80), which is generated in situ from triphenylphosphine, iodoform and potassium butoxide. 

Di-0-isopropylidene-a-D-rtbo-hexofuranos-3-ulose (100) was treated with (chlorofluoromethylene)triphenylphosphorane (prepared by reaction of triphenylphosphine on difluorocarbene generated in situ by reaction of potassium ferf-butoxide with dichloro-fluoromethane), to give cis- and rans-3-C-(chlorofluoromethylene)-3-deoxy-l,2 5,6-di-0-isopropylidene-a-D-ribo- (101 and 103) and -xyfo-hexofuranoses (105 and 107), which, on treatment with lithium aluminum hydride, gave cis- and frans-3-deoxy-3-C-(fluoromethyl)-1,2 5,6-di-O-isopropylidene-a-D-rtbo- (102 and 104) and -xyZo-hexofura-... 

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. 

Nucleophiles attack the imide sulfur atom of trithiadiazepines. Trithiadiazepine (29, R = H) is converted by potassium t-butoxide and iodomethane into 3,4-dimethylthio-l,2,5-thiadiazole (30) by a rearrangement in which two of the ring sulfur atoms have become exocyclic with triphenylphosphine (29, R = C02Me) gives dimethyl l,2,5-thiadiazole-3,4-dicarboxylate (28) (87JCS(Pl)2i7). 

The thioimidoester (60.0g, 319mmol), triphenylphosphine (334g, 1.28 mol) and anhydrous xylene (550 ml) were combined in a flame-dried 1000 ml three-necked flask. A solution of potassium t-butoxide (3.57 g, 32.0 mmol) in t-butyl alcohol (20 ml) was added dropwise and the reaction mixture was stirred at room temperature for 4h and then refluxed for 60 h. It was cooled and extracted three times with 10% HC1 (3X 150 ml). The combined aqueous extracts were washed three times with ether (3 X 50 ml), neutralized with solid sodium hydrogencarbonate and extracted with four portions of dichloromethane (4 X 100 ml). The combined dichloromethane layers were washed twice with brine (2 X 80 ml), dried over MgS04 and concentrated to give a crude brown solid which was sublimed (40°C/0.1 torr) to yield (1) (37.6 g, 76%), m.p. 62-63°C. 

Bis(l, 5-cyclooctadiene)nickel(0), 35 t-Butyllithium, 58 Diacetatobis(triphenylphosphine)-palladium(II), 91 Menthol, 172 Mercury(II) chloride, 175 Palladium(II) acetate, 232 2-(Phenylseleno)acrylonitrile, 244 Potassium t-butoxide, 252 Tributyltin hydride, 316 Triphenyltin hydride, 335... 

Allyltriphenylsilane, 13 Diacetatobis(triphenylphosphine)-palladium(II), 91 Dichlorobis(triphenylphosphine)-palladium(II), 103 (3-Dimethylaminopropyl)triphenyl-phosphonium bromide, 119 Lithium diisopropylamide-Potassium r-butoxide, 164... 

Containing one nitrogen, one oxygen Dichlorotris(triphenylphosphine)-ruthenium(II), 107 Potassium t-butoxide, 252 Containing two nitrogens Dichlorotris(triphenylphosphine)-ruthenium(II), 107 Trimethylamine N-oxide, 325... 

Potassium t-butoxide, 252 Triphenylphosphine dibromide, 333 Triphenylphosphine-2,2 -Dipyridyl disulfide, 332 Zinc iodide, 350 y-Lactams... 

The nucleophilic character of triphenylphosphine and the electrophilic character of carbenes suggested to two groups of investigators that the two reagents should combine to form ylides of a new type to use in expansion of the Wittig reaction. Speziale et ai. found that triphenylphosphine on treatment in pentane with chloroform and potassium t-butoxide at 0° gives yellow triphenylphosphine dichloromethylene, which reacts with benzophenone to yield I,l-diphenyl-2,2-dichloroethylene (1). 

Phosphorus ylids are prepared by treatment of phosphonium salts with bases such as phenyllithium, butyllithium. dimsyl anion, or potassium f-butoxide. They are not isolated but used directly after preparation because they are sensitive to oxygen and moisture. The requisite phosphonium salts are available in great variety from the reaction of triphenylphosphine and primary or secondary alkyl halides, usually bromides [24]. 

Bases Alumina, see p-Toluenesulfonylhydrazine. Dehydroabietylamine. 1,5-Diazabicyclo [4.3.0]nonene-5. 1,4-Diazabicyclo[2.2.2]octane. l,S-Diazabicyclot5.4.0]undecene-5. 2,6-Di-/-butylpyridine. N,N,-Diethylglycine ethyl ester, see /-Amyl chloroformate. 2,6-Dimethyl-piperidine. Ethanolamine. Lithium diisopropylamide, see Diphenylsulfonium isopropylide. Lithium nitride. Magnesium methoxide. N-Methylmorpholine. Piperidine. Potassium amide. Potassium hydroxide. Potassium triethylmethoxide. Pyridine. Pyrrolidine. Sodium methoxide. Sodium 2-methyl-2-butoxide. Sodium thiophenoxide. Thallous ethoxide. Triethyla-mine. Triphenylphosphine, see l-Methyl-2-pyrrolidone. 

DEHYDROHALOGENATION Potassium f-butoxide. Potassium hydroxide. Sodium amide. Tetrakis(triphenylphosphine)palladium(0). 

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