Vinyl phosphonium bromide

VINYL TRIPHENYLPHOSPHONIUM BROMIDE (Phosphonium bromide, triphenylvinyl-)... 

In vinylic phosphonium salts, the jft-carbon is found to be substantially deshielded (A<5 = 22.4 ppm for the vinyltriphenylphosphonium bromide as compared with ethylene), although only a small inductive effect was expected. The extent of this was interpreted to be a consequence of pn-dn bonding between phosphorus and carbon39. This argument was used to identify structures when or 31PNMR spectra failed96. 

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)... 

Reaction of cis-6H,9aH-2-(ferf-butoxycarbonyl)perhydropyrido[l,2-fl] pyrazine-6-aldehyde with ylide, formed from (3-chlorobenzyl)(triphe-nyl)phosphonium bromide with BuLi, furnished 6-[(E)-2-(3-chlorophe-nyl)vinyl] derivative (07USA2007/037817). The treatment of cis-6H,9aH-... 

To obtain more information on the nature of the quasiphosphonium intermediates involved in these systems we have studied the reactions gf sterically hindered neopentyl esters by means of 1P nmr spectroscopy. Trineopentyl phosphite and a-bromoacetophenone gave rise to a peak at +41 ppm due to the ketophosphonium intermediate 3 (R = Me.CCH, R = Ph X = Br ) within half an hour of mixingJthe reactants in acetone-dfi at 27 °C ( p nmr shifts are relative to 85% H-PO. down-field positive). Peaks due to the ketophospnonate 4 +19 ppm and the vinyl phosphate 7 (-7 ppm) were also observed (compound 4 and 7 have satisfactory elemental analysis and spectroscopic data ). The concentration of the intermediate reached a maximum after about two hours when it was precipitated from acetone solution by the addition of anhydrous ether to give white crystals of trineopentyloxy (phenacyl)phosphonium bromide, identified by elemental analysis and nmr spectroscopy ( XP 6+41, in CDCl ). When redissolved in acetone-dg, deuterochloroform, acetic acid, or acetic acid-acetone mixtures, the intermediate decomposed to yield keto-phosphonate 4 but none of the vinyl phosphate 6 (Perkow product). Nor was the course of reaction affected by the addition of chloride ion or of a-chloro-acetophenone in acetonitrile. 

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>. 

Heterocycles Acetylacetone. N-Aminophthalimide. Boron trichloride. Dichloro-formoxime. Oicyanodiamide. Dicyclohexylcarbodiimide. Dietboxymethyl acetate. Diethyl oxalate. Diketene. Dimethylformaniide diethylacetal. Diphenyldiazomethene. Ethyl ethoxy-methylenecyanoacetate. Formaldehyde. Formamide. Formamidine acetate. Formic acid. Glyoxal. Hydrazine. Hydrazoic acid. Hydroxylamine. Hydroxylamine-O-sulfonic acid. Methyl vinyl ketone. o-Phenylenediamine. Phenylhydrazine. Phosphorus pentasullide. Piperidine. Folyphosphoric acid. Potassium diazomethanedisulfonate. Sodium ethoxide. Sodium nitrite. Sodium thiocyanate. Tetracyanoethylene. Thiosemicarbozide. Thiourea. Triethyl orthoformate. Tris-formaminomethane. Trityl perchlorate. Urea. Vinyl triphenyl-phosphonium bromide. 

A number of cycloaddition reactions involving allene derivatives as dienophiles have been recorded. Allene itself reacts only with electron-deficient dienes but allene carboxylic acid or esters, in which a double bond is activated by conjugation with the carboxylic group, react readily with cyclopentadiene to give 1 1 adducts in excellent yield. For example, the allene 12 gave, with very high yield and selectivity, the cycloadduct 13, used in a synthesis of (-)-P-santalene (3.19). An allene equivalent is vinyl triphenylphosphonium bromide, which is reported to react with a number of dienes to form cyclic phosphonium salts. These can be converted into methylene compounds by the usual Wittig reaction procedure (3.20). 

The desired building block 189 was obtained by partial reduction of the triple bond in 203, followed by successive protection of the primary alcohol, oxidation of the secondary hydroxy group to the corresponding ketone, deprotection of the alcohol, Grignard reaction with vinyl magnesium bromide (39) and acetylation. The C2o-building block 189 was converted, with PPha HBr, into the phosphonium salt 204, and reaction of this with the Cio-dialdehyde 42 gave C.p. 450 (439) (Scheme 47). 

PRA Prasad, M., Moulik, S.P., Wardian, A.A., Moore, S., Bonunel, A. van, and Palepu, R., Alkyl (Cio, C12, Ci4 and Cie) triphenyl phosphonium bromide influenced cloud points of nonionic surfactants (Triton X 100, Brij 56 and Brij 97) and the polymer poly(vinyl methyl ether). Coll Polym. Sci., 283, 887, 2005. 

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