Triphenyl phosphonium bromide

Propargyl triphenyl phosphonium bromide [2091-46-5] M 381.4, m 179°. Recrystallises from 2-propanol as white plates. Also crystallises from EtOH, m 156-158°. IR has V 1440, 1110cm (P-C str). [Justus Liebigs Ann Chem 682 62 1965 J Org Chem 42 200 1977]. 

Carbohydroxy-n-butyl)triphenyl-phosphonium bromide Sulprostone... 

Bei einer anderen Zweistufen-Variante der Schweizer-Reaktion werden die aus prima-ren Aminen und Ethenyl-triphenyl-phosphonium-bromid erhaltlichen (2-Alkylamino-ethyl)-triphenyl-phosphonium-bromide nach Lithiierung mit 2-Aquivalenten Butyl-lithium in einer Carbonyl-Olefinierungsreaktion mit Aldehyden zu 1-Alkylamino-2-al-kenen umgesetzt2. Es entstehen uberwiegend die ( )-Isomeren. 

Methyl triphenyl phosphonium bromide (0.56 mmol) was dissolved in 10 ml of THF and treated with 1.6 M -butyl lithium (0.64 mmol) in hexane solution at 0°C. The solution was stirred for 30 minutes at 0°C and then treated with the step 2 product (0.36 mmol) and stirred an additional 2 hours at ambient temperature. The solution was treated with dilute hydrochloric acid, extracted with chloroform, dried over MgSC>4, and concentrated. The residue was purified by silica gel column chromatography using chloroform/hexane, 2 1, respectively, recrystallized using CH2CI2/ methanol, and 100 mg of product isolated. 

Propargyl triphenyl phosphonium bromide [2091-46-5J M 381.4, m 179". Recrystallises from... 

Cyclohexene annelation.1 Reaction of ketone enolates with 2 equiv. of this salt results in two sequential Michael reactions to give a cyclohex-enyl(triphenyl)phosphonium bromide, which can be hydrolyzed to a cyclohex-enyl(diphenyl)phosphine oxide.1... 

Cesium fluoride-Tetraalkoxysilanes, 69 Hexamethylphosphoric triamide, 142 Methyl acrylate, 183 a-Methylbenzylamine, 185 Methyl vinyl ketone, 193 Potassium t-butoxide, 252 Potassium f-butoxide-Xonotlite, 254 Potassium fluoride-Alumina, 254 Tin(II) trifluoromethanesulfonate, 301 Titanium(IV) chloride, 304 Trityl perchlorate, 339 Vinyl(triphenyl)phosphonium bromide, 343... 

Thioethoxycarbonylmethylenetri-phenylphosphorane, 296 Vinyl(triphenyl)phosphonium bromide, 343... 

By Wittig and related reactions (3-Dimethylaminopropyl)-triphenylphosphorane, 119 Sodium amide, 278 Vinyl(triphenyl)phosphonium bromide, 343 (E)-Alkenes By elimination reactions Arylselenocarboxamides, 22 Dichlorobis(cyclopentadienyl)-titanium, 102 Hydrogen peroxide, 145 From three-membered heterocycles Tributyltinlithium-Trimethylalu-minum, 320 Trisubstituted alkenes Chloromethyldiphenylsilane, 74 Organocopper reagents, 207 Alkenes (Methods to form alkenes)... 

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

Another highly versatile building block derived from diacetone-glucose 54 is the 1,2-acetonide of 3-C-methyl-a-D-allose in its furanoid form 57, which has been utilized as the key compound in a convergent total synthesis of ACRL Toxin I (63). Its elaboration from 54 starts with a pyridinium dichromate / acetic anhydride oxidation (64), is followed by carbonyl olefination of the respective 3-ulose with methyl (triphenyl)phosphonium bromide and hydrogenation (— 55 56), and is completed by acid cleavage of the 5,6-isopropylidene group. This four-step process 54 -> 57, upon optimization of reaction conditions and workup procedure, allows an overall yield of 58 % (63), as compared to the 22 % obtained previously (65). 

Intramolecular palladium-catalyzed cyclization reactions have also been used to synthesize pyrazole derivatives. iV-Aryl-iV-(o-bromobenzyl)hydrazines 494 participated in a palladium-catalyzed intramolecular amination reaction to give 2-aryl-2//-indazoles 495 (Equation 101) <20000L519>. Palladium-catalyzed intramolecular C-N bond formation of iV-acetamino-2-(2-bromo)arylindolines 496, followed by hydrolysis and air oxidation in the presence of aluminium oxide, allowed the preparation of indolo[l,2-3]indazoles 498 via intermediate 497 (Scheme 58) <2002TL3577>. 3-Substituted pyrazoles have been prepared from the intramolecular cyclization of A -tosyl-iV-(l-aryl/ vinyl-1-propyn-3-yl)hydrazine and then exposme of the reaction mixture of the cyclization to potassium /i //-butoxide <1997SL959>. iV-Aryl-iV -(o-bromobenzyl)hydrazines 499 or [A -aryl-A -(t>-bromobenzyl)hydrazinato-A ]-triphenyl-phosphonium bromides 501 participated in a palladium-catalyzed intramolecular amination reaction to give 1-phenyl-l//-indazoles 500 (Scheme 59) <2001TL2937>. 

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